SURGICAL AND DIAGNOSTIC ANESTHESIA, INCLUDING

Because atracurium and cisatracurium are metabolized via Hoffmann elimination, they are safe for use in patients with cirrhosis.
Halothane is the volatile anesthetic that most decreases hepatic blood flow.
Remifentanil is metabolized by plasma esterases so it is minimally, if any, effected by liver failure.
Hypercapnia increases blood flow to the liver greater than positive pressure ventilation, volatile anesthetics, and PEEP.

GASTROINTESTINAL

Carcinoid tumors are constituted by Kulchitsky cells.
Anesthesia management of patients with carcinoid syndrome include avoiding agents that are histamine-releasing as well as those that are sympathomimetics.

Endocrine Organ Procedures

ADH release is decreased by negative pressure ventilation.

PHEOCHROMOCYTOMA

- These tumors are usually found in the adrenal medulla.
- These patients should be alpha blocked first, IV fluids replaced, and then beta blocked.
- After the tumor removal, IV fluids and phenylephrine (alpha blocker) are useful in the treatment of hypotension.

RENAL/GENITOURINARY

Prolonged renal hypoperfusion is the most common cause of acute kidney injury.
A 250 mL bolus is safe for patients with renal compromise.
A glomerular filtration rate (GFR) of 60 mL/min for 3 months is indicative of chronic kidney disease.
Persistent oliguria is a relative indication for renal replacement therapy.
Plasma creatinine level is a preoperative laboratory test that evaluates glomerular filtration rates.
Urine sodium concentration is a preoperative laboratory test that reflects renal tubular function.
Decreased excretion of hydrogen ions is a characteristic of chronic kidney disease.
Of the interventions used to correct hyperkalemia, calcium chloride lowers serum potassium the least.
Metabolic acidosis is the most likely acid/base disturbance in chronic kidney disease.
Decreased exchange for calcium in the distal nephrons is a cause of hyperkalemia that is seen in chronic kidney disease.
Cardiac output is increased because of anemia and delivery medications to brain quicker (also, uremia alters the blood-brain barrier which increases sensitivity). There is a decrease in protein binding which leaves more active/free drug circulating. With decreased excretion, the free drug circulates longer as well. The volume of distribution is increased but it does fluctuate with dialysis. Platelet function is altered and leads to increased bleeding times.
Owing to Hoffmann metabolism, neither atracurium nor cisatracurium are renally metabolized.
During a TURP with regional anesthesia, the patient develops abdominal pain and sudden nausea/vomiting. The most likely cause is bladder perforation.
To help prevent TURP syndrome, one measure is keeping the prostate capsule intact until the end of the resection.
Hyperglycinemia can cause vision loss in TURP patients which is often reported by the patient in PACU.
The risk of central pontine myelinolysis increases when hyponatremia is corrected ≥ 3 mEq/hr.

Gynecologic

Peritoneal Procedures (Including Hernia Repair)

Ilioinguinal and iliohypogastric nerves are blocked.

Extrathoracic

BREAST

Breast augmentation is usually performed under general anesthesia because separating the pectoralis muscles from the chest wall is painful.
Breast surgery has a high likelihood of PONV.

Types
- Simple mastectomy: removal of breast tissue, nipple, areola
- Radical mastectomy: breast, areola, skin, underlying pectoralis muscles, and axillary lymph nodes are removed
- Modified radical mastectomy: similar to the radical but spares the pectoralis muscles and improved cosmetic appearance
- Sentinel lymph node biopsy, axillary lymph node dissection: requires incision within the axilla (T1) and is a more extensive dissection
- Reconstruction or tissue expander replacement: unilateral or bilateral, mastectomies can be completed during the initial surgery or later; muscle relaxation is required

Regional anesthesia
- Thoracic paravertebral block
  - Requires multiple injections for coverage
  - Risk of pleural puncture is higher
  - Does not cover the pectoral muscles
  - Can be the primary anesthetic
- Pectoral nerve block II (PECS II)
  - One needle insertion
  - Pectoral muscles are anesthetized
  - Can be the primary anesthetic
- Erector spinae plane block
  - Not a neuraxial technique
  - Decreased risk of pleural puncture
  - Typically used for postoperative analgesia
- Thoracic epidural
  - Can be sole anesthetic or for postoperative pain control
  - High failure rate
  - Side effects are more common; hypotension with a sympathectomy and epidural opioids

Because nerve muscle function is routinely assessed, neuromuscular blocking agents should not be used.

PLASTICS and/or RECONSTRUCTIVE

Liposuction is the most common procedure performed by plastic surgeons and dermatologists. Subcutaneous fat is suctioned through a hollow rod with infiltrate solutions and local anesthetics with epinephrine.
- Traditionally, the max dosage of lidocaine with epinephrine is 7 mg/kg but with the tumescent technique, doses as high as 35-55 mg/kg has been safely used. This technique results in single compartment clearance that mimics a sustained-release medication. Peak serum levels of lidocaine are seen 12-14 hours after injection.
Aesthetics, like blepharoplasty and rhinoplasty, can be performed under MAC or general. Fire precautions should be adhered to when lasers and/or electrocautery are used.
When IV dye is injected during a sentinel node biopsy, there is a false drop in the pulse oximetry ready.
As with any flap or graft procedure where vasoconstriction may negatively affect the blood supply, vasoconstrictors should not be used in TRAM reconstructions.

REFERENCE: Barash, Clinical Anesthesia 9^th edition, pages 839-841

Head

Extracranial

OTOLARYNGOLOGICAL

The narrowest portion of the larynx in adults is the rima glottidis.
The gag reflex is controlled by the glossopharyngeal nerve.
Neuromuscular blocking agents can alter electromyography by decreasing amplitude during ENT surgeries with cranial nerve monitoring.
The pediatric patient who is being transported to the PACU after an adenotonsillectomy should be in the lateral position with the head slightly down.
The most common reason for unscheduled overnight stays after ambulatory surgery is persistent nausea and vomiting.
Hypocalcemia can develop 24-96 hours after thyroid surgery.

OPHTHALMOLOGIC

The pairing that accurately describes the oculocardiac reflex is afferent/trigeminal and efferent/vagus.
When a patient is treated with intravitreal sulfur-hexafluoride bubble injection for detached retina repair, the CRNA should discontinue nitrous oxide 15 minutes before the injection.
The lateral rectus is an orbital muscle that is controlled by cranial nerve VI.
- The lateral rectus muscle abducts the eye.
Cranial nerve III controls two orbital muscles- superior rectus and inferior oblique.
- The inferior oblique orbital muscle originates from the anterior nasal orbital floor and moves in a posterolateral direction along the globe, inserting inferiorly to the macula of the globe.
Atropine is an ocular medication that acts as a pupillary dilator and causes temporary paralysis of the ciliary muscle.

NASAL

Most common procedures are for drainage of chronic sinusitis, polyp removal, deviated septal repair, or closed reductions. These patients often suffer from allergies so their airway is reactive.
To improve surgical view, some of these techniques may be employed:
- Turn the bed away from anesthesia machine
- Surgeon and crew in the airway- possibility of extubation
- Blood, fluid, and infection can contaminate the airway
- Hypotensive technique, head of bed elevated, and vasoconstrictors in the nose are often employed

CRANIOFACIAL

The most common site of traumatic fracture of the spine is C7.

Le Fort I – Horizontal fracture of the maxilla extending from the floor of the nose and hard palate, through the nasal septum, and through the pterygoid plates posteriorly.

Le Fort II – A triangular fracture running from the bridge of the nose, through the medial and inferior wall of the orbit, beneath the zygoma, and through the lateral wall of the maxilla and the pterygoid plates.

Le Fort III – Fracture totally separates the midfacial skeleton from the cranial base, traversing the root of the nose, the ethmoid bone, the eye orbits, and the sphenopalatine fossa.

Nasal intubation is acceptable in the trauma patient who has a Le Fort I facial fracture.

PLASTICS and/or RECONSTRUCTIVE

The first surgery for cleft palate usually occurs at 3 months old. The next repair, which involves the closure of the posterior hard palate and soft palate, occurs at 5-8 months of age. Widely accepted preoperative guidelines include the rules of 10: weight at least 10 pounds, hemoglobin at least 10 g, WBC less than 10,000/mm3, and age more than 10 weeks.
The Logan bow is placed after cleft lip surgery and makes mask ventilation difficult or impossible. Therefore, the patient should be awake with intact reflexes.

ORTHODONTIC/DENTAL

Pediatric dental patients can be induced with an IV but most often an inhalational induction is utilized. Patients may be given midazolam PO preop. Patients with a history of seizures who are compliant with their anticonvulsants may require an increased dose of anesthetics. Phenytoin, a common anticonvulsant, can cause gingival hyperplasia and lead to significant blood loss.

Intracranial

The predominant glial cell in the CNS is an astrocyte.
Schwann cells are glial cell that provide insulation in the peripheral nerves.
Resting nerve cells are “polarized.”
Depolarization occurs when a stimulus of sufficient intensity (threshold potential) increases membrane permeability for more sodium ions to enter the cell than potassium ions can exit.
The threshold for this action potential can be physiologically altered:
- Alkalosis- increases neuronal excitability
- Hypoxemia and acidosis- decreases neuronal excitability
Neurotransmitters are excitatory if they increase the sodium permeability of the axolemma.
- Acetylcholine and glutamate
Neurotransmitters that are inhibitory cause the membrane to increase chloride ion permeability and lead to a hyperpolarized state.
- GABA and glycine

Acetylcholine

Histamine

Dopamine

Norepinephrine

Substance P

Glutamate

Glycine

GABA

Cholinergic receptors

Requires cyclic adenosine monophosphate

Basal ganglia

Reticular activating system and hypothalamus

Substantia gelatinosa

Cerebral cortex and hippocampus

Spinal cord

Major inhibitory neurotransmitter in the CNS

The enzyme that is responsible for the breakdown of catecholamines is monoamine oxidase.
The ion that is responsible for the release of neurotransmitters from the presynaptic neuron is calcium.
The total volume of cranial and spinal CSF in adults is 150 mL.
The ependymal cells of the choroid plexus secrete 30 milliliters per hour of CSF.
The brain receives 50 mL/100 g/min of cardiac output.
The basilar artery supplies the posterior circulation of the brain.
Magnesium is higher in CSF when compared to normal plasma concentrations.
Saltatory conduction:
- Electrical impulse is propagated along the nodes of Ranvier.
- Schwann cells
The medulla oblongata is responsible for inhibiting respiration while swallowing.
During nerve monitoring involving the facial, recurrent laryngeal, vagal, and others, the CRNA should avoid using neuromuscular blocking agents and local anesthetics.
Cranial nerve II (OPTIC) is covered by the meninges- arachnoid, pia, and dura mater. It is not a true cranial nerve but an outgrowth of the brain.
Cranial nerves I (OLFACTORY), II (OPTIC), and VIII (VESTIBULOCOCHLEAR) are purely sensory.
Cranial nerves III (OCULOMOTOR), IV (TROCHLEAR), VI (ABDUCENS), XI (ACCESSORY), and XII (HYPOGLOSSAL) are purely motor.
Cerebral blood flow is lowered by 4% for a decrease in P_aCO₂ of 1 mm Hg.
Cerebral metabolic rate of oxygen (CMRO₂) decreases 7% for each 1^o C decrease in body temperature.
Hypothermia can be used to lower ICP within the first 24 hours (unlike hyperventilation) and in the presence of hypernatremia/CHF (unlike mannitol and hypertonic saline infusion).

NEURO PHARMACOLOGY

Labetalol can be used for controlling hypertension without increasing ICP. This antihypertensive attenuates the hyperdynamic response to intubation while maintaining optimal conditions for intracranial surgery.
Inhalational agents decrease cerebrovascular resistance by cerebrovascular dilation and dose-dependent autoregulation impairment. This produces an increase in ICP and CBV and a decrease in CMRO₂.
- Isoflurane increases CBF and ICP the most, then sevoflurane and desflurane.
- Nitrous oxide use is controversial.
CMRO₂ is increased by sympathetic stimulation, like laryngoscopy, seizures, and ketamine.
Propofol decreases ICP, whereas inhalational agents and ketamine both increase ICP. Nitrous oxide may decrease ICP or have no effect. Again, nitrous oxide use in neuroanesthesia is controversial.
Dexmedetomidine, an alpha-2 agonist, is IDEAL for awake craniotomies because it provides:
- Anxiolysis and analgesia without respiratory depression.
- Sedation that closely resembles sleep patterns more than those seen with propofol which helps with “wake-up” tests.
- The opportunity for sedation/anesthesia without effecting electrophysiologic monitoring.
- No effect on CMRO₂ but does decrease CBF. Effects on ICP are negligible.
- A central sympatholytic effect which reduces the neuroendocrine stress response to surgery.
Dexmedetomidine decreases CMRO₂ more than etomidate, thiopental, and propofol.
The opioid that decreases cerebral perfusion pressure (CPP) the most is alfentanil.
Dexamethasone is a medication that can cross the BBB.

DECOMPRESSION (BURR HOLES, VENTRICULOPERITONEAL SHUNT)

Ventriculoperitoneal shunts are usually inserted via right craniotomy because this provides a more direct route for peritoneal insertions.
Intracranial pressure is measured in the lateral ventricle.
The gold standard for intracranial monitoring is the intraventricular catheter.
ICP is pulsatile and are made up of three distinct parts:
- Heart pulse waves
- Respiratory waves
- Slow vasogenic waves (Lundberg B waves)
ICP waveforms:
- P₁– first and usually the tallest; percussion wave; corresponds with SBP
- P₂– tidal wave
- P₃– dicrotic wave
Pearls for ICP waveforms:
- With increased ICP, P₂ and P₃ eventually surpass P₁.
- Increased ICP causes the waveform to lose its peaks and assume plateau waves, called A waves of Lundberg.
Intracranial HTN is seen when CSF compensation is exhausted.
Electroencephalogram (EEG) monitors the pyramidal layer of the cerebral cortex.
SSEPs monitor the brain’s response to a repetitive stimulus along a specific nerve pathway.
- Etomidate and ketamine increase the amplitude.
- Inhalational anesthetics depress the waveform dose-dependently.
- Hypothermia increases latency.
- Hyperthermia suppresses amplitude.
Brainstem auditory-evoked potentials (BAEP) monitor cranial nerve VIII (VESTIBULOCOCHLEAR).
Monro-Kelly doctrine
- Because the brain is not compressible and resides within the cranium, any increase in intravascular volume will result in an increase in ICP.
- Mechanism to regulate normal ICP.
Intracranial space:
- Brain- 80-90%
- Blood
- Intracellular water
- CSF
If one of these 4 increases in volume, there must be a subsequent and equal decrease to keep ICP normal.
Increased intracranial pressure is above 15 mm Hg.
Two mechanisms by which intracranial pressure is maintained when fluctuations in intracranial volumes are present:
- Shifting of CSF from intracranial to spinal subarachnoid space
- Shifting of blood into the systemic circulation
When the cerebrospinal fluid compartment cannot decrease anymore in the presence of increasing intracranial mass, ICP increases.
Elevating the head of bed by 15^O can lower ICP.
Hyperventilation induces hypocapnia and thereby decreases in CBF, overall cerebral fluid volume, and ICP. Because vasoconstriction can lead to cerebral hypoxia, this intervention is NOT recommended in the first 24 hours after a traumatic brain injury or prophylactically.
Venous air embolism
- 5 mL/kg of air- decreased ETCO₂, increased ETN₂, oxygen desaturation, altered mental status, and wheezing.
- 5-2 mL/kg- difficulty breathing, wheezing, hypotension, ST changes, peaked P waves, jugular venous distention, myocardial/cerebral ischemia, bronchoconstriction, and pulmonary vasoconstriction.
- > 2 mL/kg- chest pain, right-sided heart failure, and CV collapse.
The most sensitive non-invasive monitor for venous air embolism is the precordial doppler.
During a venous air embolism, the first action is to notify the surgeon.

SPACE-OCCUPYING LESION

Cerebral blood flow is increased by hypercarbia (the cerebral vasculature dilates) and is decreased by hypocarbia (the cerebral vasculature constricts).
To prevent cerebral ischemia in a patient with an intracranial tumor, P_aCO₂should be maintained between 30-35 mm Hg preoperatively.
Cushing’s reflex occurs in response to cerebral ischemia due to increased ICP. It is triggered when the ICP elevates greater than MAP, which leads to decreased cerebral perfusion and ischemia.
- Cerebral ischemia must be resolved or infarction occurs. This reflex is a late sign of high and sustained ICP prior to herniation.
- Cushing’s triad:
  - HTN
  - Bradycardia
  - Respiratory rhythm irregularity
- In posterior fossa surgeries, bradycardia and HTN can result from stimulation of the trigeminal nerve.
- A posterior fossa lesion is associated with obstructive hydrocephalus.
- The IV fluid that is used for supratentorial mass surgery is normal saline.
- Awake craniotomies should not be attempted in those with developmental delay, lack of maturity, exaggerated/unacceptable pain response, communication barrier, or failure to obtain consent. Seizures management should be optimized.

VASCULAR

Aneurysms are abnormal, localized dilations of the intracranial arteries.
Subarachnoid hemorrhage (SAH) produces an abrupt, intense headache in 85% of patients, and transient loss of consciousness in up to 45%.
Hypertension often accompanies acute SAH and is believed to occur secondarily to autonomic hyperactivity, which may increase transmural pressure in the aneurysmal sac. Transmural pressure is the difference between MAP and ICP and is the stress on the aneurysm’s wall. TMP = MAP – ICP
To balance the risk of bleeding with hypertension and ischemia from hypotension, SBP should be kept between 120-150 mm Hg before clipping the aneurysm.
Cerebral artery vasospasm is a delayed and sustained contraction of cerebral arteries. Vasospasm is reactive narrowing of cerebral arteries after SAH. Vasospasm causes a decrease in blood flow and a resultant lowering of CPP.
Nimodipine is an oral calcium channel blocker that is used to prevent vasospasm after neurologic trauma or hemorrhage.
Triple-H therapy
- Hypervolemia- CBF depends on intravascular volume and MAP; generally achieved with colloids as well as crystalloids.
- Hypertension- maintains CPP and helps prevent ischemia.
- Hemodilution- hematocrit of 27-30%
Hypertensive, hypervolemia therapy could induce a vagal response so atropine may be needed.
Before clipping, the SBP needs to be 120-150 mm Hg. Post-clipping, the SBP should be high enough to reverse symptoms of a vasospasm or up to 160-180 mm Hg.
Burst suppression is preferred on EEG prior to temporary clipping of a cerebral aneurysm.
Anesthesia considerations:
- Mild hyperventilation
- When using local for infiltration, do NOT use epinephrine
- Even though succinylcholine can increase ICP, no definitive evidence that it is relevant. Rocuronium is safe to use.

TRANSSPHENOIDAL HYPOPHYSECTOMY

The most common complication for pituitary tumor resection via the transsphenoidal approach is diabetes insipidus.
After this procedure, diabetes insipidus may occur where large amounts of dilute urine are excreted. Fluid and electrolyte monitoring is needed. Vasopressin or desmopressin are indicated for treatment.
Visual evoked potential monitoring may be used if the tumor is large enough that it involves the optic nerves (cranial nerve II).

STEREOTACTIC PROCEDURES

Stereotactic procedures treat:
- Movement disorders
- Intractable pain
- Epilepsy
- Diagnosis/treatment of intracranial tumors

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Cardiac Anesthesia

Open Procedures (CABG)

ANATOMY AND PHYSIOLOGY

Myocardial O2 demand is regulated by these three: myocardial wall tension, heart rate, and contractility. The anesthetic management’s goal in coronary artery disease is to maintain the balance between myocardial O2 supply and demand.
Normally, coronary blood flow can increase 3-5 times during demand periods and is referred to as coronary reserve. However, in patients with CAD, coronary reserve is limited (or absent) and they develop demand ischemia during exercise or stress. This is known as predictable, stable angina.
In the perioperative period, the most common cause of cardiac ischemia is due to supply.
Indications for CABG:
- 3-vessel disease w/ or w/o proximal LAD disease
- 2-vessel disease with proximal LAD disease
- Severe ischemia in 2-vessel disease w/o proximal LAD disease
- Proximal LAD disease if the left internal thoracic artery (LITA) will be used
At 10-years, the patency rate of the left internal thoracic artery is 90%.

CABG

ANESTHESIA

The highest rate of recall during cardiac surgery is incision to bypass.

COAGULATION

The current guideline for activated clotting time prior to cardiopulmonary bypass initiation is 480 seconds.
An antithrombin III deficiency is suspected if an adequate dose of heparin is given and the ACT only increases to 70-100 seconds. Giving 2 units of FFP can provide the clotting factors necessary for an adequate ACT needed for going “on pump.”
The activated coagulation time (ACT) assesses heparin in the patient undergoing CABG surgery. The normal ACT is 70-110 seconds. A safe ACT value for undergoing coronary artery bypass grafting is greater than 480 seconds.
The reversal dose of protamine for each 100 units of heparin is 1.3 mg.
Protamine reverses heparin by way of neutralization.
In the absence of heparin, protamine will bind to platelets and other coagulation factors to produce anticoagulation.
Nitroglycerin reduces the effectiveness of heparin.
There is a 5-7% risk of seizure with tranexamic acid.
The only approved drug for bridging a CABG patient who is on oral anticoagulants preoperatively is unfractionated heparin.
An allergy to NPH insulin should alert the CRNA to a possible severe reaction to protamine.

CARDIOPULMONARY BYPASS

The electrolyte that is infused into the aortic root during coronary artery bypass grafting surgery to arrest the heart is potassium.
The vessels that continue to fill the left ventricle during coronary artery bypass grafting are the Thebesian veins.
Platelets drop because of a phenomenon during the hypothermia stage of cardiopulmonary bypass called sequestration.
Air most commonly will migrate to the right coronary artery when preparing to separate from bypass.
Following separation of cardiopulmonary bypass, vasopressin infusion is best for patients who develop vasoplegic syndrome.
Radial artery graft has a higher risk of spasm when compared to saphenous vein graft.
For off-pump coronary artery bypass grafting surgery, the circumflex artery requires the heart to be lifted vertically the most.

OPEN CARDIAC PROCEDURES

The most common valvular lesion requiring surgical intervention is aortic stenosis.
The most important therapeutic intervention to prevent cerebral ischemia in circulatory arrest during aortic aneurysm repair is hypothermia.

COMPLICATIONS

The biggest predictor for neurologic injury after CABG surgery is ascending aorta atherosclerosis.

Minimally Invasive Procedures (Transcatheter Aortic Valve Replacement / Implantation, Left Atrial Appendage Closure Implant, Mitral Clips)

Benefits to minimally invasive cardiac surgery (MICS) over open median sternotomy techniques:
- Decreased bleeding
- Lower rates of transfusion
- Earlier extubation
- Able to ambulate quicker
- Quicker discharge from hospital
- Infection rates are lower
- Pain is decreased
- Cosmetically more appealing
Complications with MICS compared to the traditional approach:
- Increased rates of hemorrhage
- Complications with the femoral cannulation sites
- Unilateral pulmonary edema
- High rate for conversion to traditional approach
Transcatheter aortic valve replacement/implantation
- The retrograde approach via the femoral artery is the most common.
- Because there are large vascular sheaths inserted, heparin is given to achieve an ACT of 250-300 seconds.

Interventional Cardiology (Pacemakers, Automated Internal Cardiac Defibrillator Devices, Electrophysiology Cases

Shivering can inhibit a pacemaker’s pacing function.
The pacemaker code that senses and paces both the atria and ventricles is DDD (d- dual).
Placing a magnet over a pacemaker site in the VVI setting, it defaults to VVO.
The most common reason for pacemaker insertion is bradydysrhythmias.
Indications for a pacemaker include a new symptomatic bradyarrhythmia, a new bundle brand block, second- or third-degree heart block associated with MI, and refractory supraventricular tachycardia.
The Heart Rhythm Society (HRS) recommends routine assessment every year for pacemakers.
The manufacturer whose ICD device elicits an audible tone when the magnet disables the antitachycardia therapy is Medtronic.
The first action in the event of a pacemaker failure in the OR is to place 100% oxygen on the patient and then check connectors and generator battery light. The pacemaker should be set into the asynchronous mode while reasons for the failure are assessed.
When a pacemaker’s reed switch is closed, asynchronous pacing begins.
Elective surgery should be postponed for 1 month after a bare-metal stent is placed.
Both remifentanil and dexmedetomidine should be avoided during EP studies to find abnormal electrical impulses.
The patient should abstain from routine antiarrhythmic agents before EP study so the abnormality can be mapped easier.
An esophageal temperature probe is useful because of the risk of thermal injury leading to esophageal perforation or the formation of an atrioesophageal fistula.

Management of Patients with Cardiac Devices (Ventricular Assist Device, Extracorporeal Membrane Oxygenation, Intraarterial Balloon Pump

Intraaortic balloon pump:
- IABP is placed in the descending aorta for assist patients in heart failure, to stabilize a patient preoperatively, or to help wean off CPB.
- Helium is used to inflate the balloon at the onset of diastole, displacing blood proximally toward the coronary arteries (counterpulse), thereby increasing aortic diastolic pressure (diastolic augmentation) and coronary perfusion.
- At the onset of systole, the balloon deflates, creating a vacuum that reduces afterload and myocardial oxygen demand while modestly enhancing cardiac output.
- Balloon inflation should be timed with the dicrotic notch of the arterial waveform, or the peak of the T wave on the ECG, so that inflation begins once the AV closes and is maintained through diastole.
- The augmented diastolic pressure should exceed the nonaugmented systolic pressure.
- Deflation of the balloon is timed to occur immediately before the onset of systole, at the beginning of the R wave of the ECG.
- Assisted systolic and aortic end-diastolic pressures should be less than the unassisted values.
Venovenous (V-V) extracorporeal membrane oxygenation Requires anticoagulation with heparin when flow rates are < 3 L/min.
Venoarterial (V-A) extracorporeal membrane oxygenation (ECMO) can cause ECMO lung and is indicated by increased SVR.
Aortic stenosis is a contraindication to the placement of a left ventricular Impella.

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Noncardiac Intrathoracic (Including Open and Thoracoscopic Approach)

DIAPHRAGM

Congenital diaphragmatic hernia

ENDOSCOPIC PROCEDURES (BRONCHOSCOPY, MEDIASTINOSCOPY)

MEDIASTINOSCOPY

During a mediastinoscopy, monitoring the blood pressure via right radial arterial line ensures the innominate artery is not compressed.
The vessel that is most likely to be compressed during a mediastinoscopy is the brachiocephalic artery (before dividing into the right common carotid artery and right subclavian artery). This can lead to decreased blood flow and potential CVA. Therefore, blood flow should be monitored via radial arterial line or pulse oximetry on the right arm.
Potential complications:
- Recurrent laryngeal nerve injury
- Esophageal perforation
- Chylothorax
- Hemorrhage
- Pneumothorax
- Bronchospasm
- Dysrhythmias

ESOPHAGUS

Tracheoesophageal fistula

LUNG

ONE-LUNG VENTILATION (OLV)

Provides distinct ventilation to the separate lungs which keeps the operative lung immobile.
Fiberoptic bronchoscopy is essential to verify placement of a double-lumen endotracheal tube but commonly causes malposition.
Relative indications:
- Surgical exposure
- Severe hypoxemia from unilateral lung disease
Thoracic surgery is not an absolute indication of OLV.
Absolute indications:
- Infectious contamination of one lung
- Control of ventilation distribution
- Unilateral bronchopulmonary lavage
Methods
- Single lumen ETT that is 7.5 mm, 32-cm long
  - A disadvantage is the ability to ventilate or suction the operative lung is lost.
- Endobronchial
  - Bronchocath
  - Carlens
  - Robertshaw
  - White
- Bronchial blocker
  - Ardnt
  - Cohen
  - Coopdech
  - Univent

MANAGEMENT OF OLV

In the setting of severe hypoxemia during OLV, both lungs can be ventilated to increase oxygenation.
The distance from the carinal bifurcation to the right upper lobe is 1.5-2 cm and 4-5 cm to the left mainstem bronchus. A descending thoracic aortic aneurysm can compress or erode the left main bronchus. Almost all thoracoscopic surgeries can be managed with the bronchial lumen inserted into the left lung.
A double lumen ETT is preferred over a bronchial blocker when lung deflation is warranted.
A ventilatory parameter that aligns with contemporary one-lung ventilation understanding and goals is permissive hypercapnia < 60 mm Hg.
OLV causes inflammatory changes in both the dependent and nondependent lungs. Protective ventilation should be utilized for prevention.

OTHERS

Hypoalbuminemia is the most common laboratory finding and serves as an important predictor of pulmonary complications. This factor increases postoperative risk as much as 2.5 times.
VO₂ (maximum amount of oxygen your body can absorb and use during exercise) pulmonary function test best assesses cardiopulmonary reserve.
Hypoxic pulmonary vasoconstriction (HPV) diverts blood to the dependent lung in the anesthetized patient via one-lung ventilation with an open chest in the lateral position.

THORACOTOMY

The dependent arm is the correct site for arterial pressure monitoring in a patient undergoing a thoracotomy.
Pulse oximetry is recorded on the dependent hand if an arterial line is not inserted.
External jugular placement is more easily kinked in the lateral position. Subclavian placement SHOULD be on the operative side. If the nonoperative side is chosen and a pneumothorax occurs, it can lead to severe hypoxemia.
Thoracoscopy (surgical exposure) is a relative indication for one-lung ventilation. Absolute indications for lung separation are hemorrhage, unilateral lung infection, and life-threatening hypoxemia related to unilateral lung disease.
Right-sided surgery carries a higher risk of hypoxemia in the setting of thoracic surgery.
Repositioning patient from supine to lateral during one-lung ventilation will improve oxygenation in thoracic surgery. Other interventions that improves oxygenation: ligation of pulmonary artery during pneumonectomy, PEEP to the dependent lung, and CPAP to the nondependent lung.
Video-assisted thoracoscopic surgery (VATS):
- Allows the surgeon less room to manipulate and compress the operative lung. Therefore, a DLT is preferable to a bronchial blocker.
- Is less painful than the open procedure so an epidural placed for post-op pain control is rarely needed.
- Improves the quality of life in the first year postoperatively when compared to the open approach.
Bullectomy:
- COPD patients benefit from this surgery because the ruptured bullae can lead to pneumothorax or tension pneumothorax.
- Maintain spontaneous respirations until chest is opened.
- Avoid high airway pressures and N₂
POSTOPERATIVE COMPLICATIONS
- Risk factors:
  - Dyspnea; chest x-ray changes; oxygen administration that is needed; auscultated changes; cough; and bronchial secretions.
- The most common complications:
  - Respiratory failure
  - Cardiac dysrhythmia
  - ALI (acute lung injury)
- Pulmonary intravascular pressures can be decreased by limiting IV intake.

MEDIASTINUM

The patient with a mediastinal mass becomes hypotensive after induction may need to be turned prone to alleviate the weight of the mass from vessels.
The patient who has venous engorgement in the upper body from a mediastinal mass may need a lower extremity IV placed.
- Other helpful interventions:
  - Induction and intubation in the sitting position
  - Limit IV fluids in the setting of superior vena cava syndrome
  - Maintain spontaneous respirations
- Thymoma
  - Myasthenia gravis (MG) is a neuromuscular junction disorder in which the postsynaptic acetylcholine receptors (AChRs) are decreased at the endplates of affected muscles.
  - MG chronically effects voluntary muscles exhibited by painless weakness and fatigability that is improved with rest. Onset is slow and the condition is associated with relapses and remissions. Most commonly effects the ocular muscles.
  - MG patients are sensitive to nondepolarizers.
  - Anticholinesterases prolong Ach at the postsynapse and may increase agonist effects at the AChRs. These drugs are the most commonly used for MG.
  - Provide steroid coverage if taking.
  - Hold AM anticholinesterase dose, unless physically or psychologically dependent.
  - Muscle relaxation can be achieved usually with inhalational agents alone.
  - If nondepolarizers are to be used, titrate only 1/10^th of the dose and monitor the effect.
  - For reversal, sugammadex is advantageous because no additional anticholinesterase therapy is needed.
  - Resistant to succinylcholine, up to 2.6 times normal.
  - Postoperative complications leading to prolonged intubation is increased when the patient is taking 750 mg of pyridostigmine daily.

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Neck

COCAINE

LIDOCAINE

BENZOCAINE

BUPIVACAINE

Vasoconstrictive properties

Rapid onset

Can produce methemoglobinemia

Long duration of action

When the head/neck/airway are manipulated for surgical purposes and there is an ETT in place, migration of the ETT into the mainstem bronchus or extubation is possible.

LARYNX/TRACHEA

TRACHEAL RECONSTRUCTION

Monitor the left radial arterial blood pressure due to the proximity of the innominate artery.
ETT is passed just superior to the lesion until the resection is complete. Then an ETT is placed distally by surgeon.
An endobronchial or DLT is needed for a low lesion. The head is down to prevent secretions and blood from entering the lungs.
Sometimes high-frequency jet ventilation is needed because surgical access is improved. However, these are more likely to kink or become occluded.

TRACHEOSTOMY

High fire risk:
- Lower FiO₂
- Suction in drapes
- Coordination with surgeon during cautery

ENDOSCOPIC SINUS SURGERIES

Microlaryngeal endotracheal tubes (MLT) is an ETT that is smaller in diameter but has a normal-sized cuff.

LYMPH NODE BIOPSIES

PARATHYROID/THYROID

HYPERTHYROID

Euthyroid in the preoperative period is the most important goal.
- 2 drugs that can be given to treat hyperthyroidism: propylthiouracil and methimazole. These drugs inhibit iodide organification and the synthesis of thyroid hormone.
Beta antagonists help to lessen the sympathetic activity in hyperthyroidism. Along with the beta blocking properties, propranolol impairs the conversion of T₄ to T₃ over 1 – 2 weeks.
Glucocorticoids reduce thyroid hormone secretion and the conversion of T₄ to T₃.
Intraoperative management involves an anesthetic depth to prevent an exaggeration in the sympathetic nervous system.
Treatment of hypotension is best with direct-acting vasopressors.
Thyroid storm is an exacerbation of hyperthyroidism. Symptoms include hyperthermia, dysrhythmias, myocardial ischemia, CHF, agitation, and confusion.
- Similar to pheochromocytoma, malignant hyperthermia, and light anesthesia.
- Management of thyroid storm:
  - IV fluids
  - Sodium iodide
  - Propylthiouracil
  - Propranolol
  - Cooling blankets
- Careful examination of the neck for goiter because of the increased chance of difficult intubation.

HYPOTHYROID

Ketamine is a useful induction agent because it stimulates the sympathetic nervous system.
Myxedema coma is an extreme form of hypothyroidism. Patients may experience hypoventilation, hypothermia, hypotension, hyponatremia, and lethargy to coma.

PERIOPERATIVE

After thyroid surgery, unilateral vocal cord paralysis will lead to hoarseness and the issue will typically compensate. Bilateral cord paralysis requires immediate reintubation because the cords close during inspiration and result in stridor (or eventually obstruction/NPPE).
Unilateral recurrent laryngeal nerve damage is the most common nerve injury associated with thyroid surgery.
Two flaccid cords after subtotal thyroidectomy indicate bilateral recurrent laryngeal damage and cord paralysis. Two flaccid cords result in airway obstruction (the cords close during inspiration) and stridor or aphonia; this necessitates reintubation.
Bilateral recurrent laryngeal nerve damage causes complete airway obstruction.
Stridor/laryngospasm after thyroidectomy results from hypocalcemia secondary to hypoparathyroidism after inadvertent removal of parathyroid glands. Laryngeal muscles are very sensitive to decreased calcium.
Hematoma is the most common at two hours postop. Laryngeal edema is found within 24 hours. Hypocalcemia generally does not occur until 24-48 hours after surgery.
Hypocalcemia can develop 24-96 hours in the postoperative thyroid surgical patient due to the inadvertent removal of parathyroid glands.
Nerve integrity monitor (NIM) endotracheal tube allows for intraoperative monitoring.

HYPERPARATHYROID

Most often due to benign adenoma but can be part of multiple endocrine neoplasia (MEN) syndrome.
Symptoms: hypercalcemia, nephrolithiasis, polyuria, polydipsia, etc.

PERIOPERATIVE

For hyperparathyroidism in the preoperative setting, IV hydration dilutes calcium levels and then inducing sodium diuresis (furosemide) will also lead to calcium excretion.
Complications include unilateral or bilateral recurrent laryngeal damage damage.
A decrease in serum calcium should be observed within the first day postoperative.

HYPOPARATHYROID

Characterized by hypocalcemia.

NECK TUMORS

RADICAL NECK DISSECTION

Cancerous tumors and neoplastic growths involving the head and neck musculature and other structures require a radical neck dissection.
Patients are malnourished. If the tumor interferes with the airway and/or radiation has been used to shrink the size of the mass, there should be a high level of suspicion for a difficult airway.
When the head is elevated, there is an increased risk of venous air embolism.
Radical lymph node dissection involves manipulating the carotid sinus and a vagal response may occur.

TONSILLECTOMY

Slow oozing of the tonsillar bed is far more common than profuse bleeding. Patients may swallow large volumes of blood before bleeding is discovered. The patient may have signs of hypovolemia evidenced by tachycardia, hypotension, and agitation. Restoration of intravascular volume and/or blood based on the volume lost should precede induction.

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Neuroskeletal

CERVICAL SPINE (ANTERIOR AND POSTERIOR APPROACH)

Postoperatively, the airway should be monitored closely due to the potential for edema and/or hemorrhage.
Careful attention is given to the airway as mobility is limited and likely to have numbness and tingling in the arms.

LAMINECTOMY/DISCECTOMY FUSIONS

Motor evoked potentials (MEPs) rely on muscle movement from nerve root stimulation for the monitoring of these pathways. Paralytic agents abolish this muscle movement and should not be used.
Reverse trendelenburg decreases blood loss. The amount of blood loss is proportional to the amount vertebral levels that are involved.
Careful positioning to avoid peripheral nerve injuries as well as to avoid abdominal compression of vessels in the prone position.

PAIN MANAGEMENT PROCEDURES

Contrast is injected to ascertain correct placement prior to pain injection. Caution in those with iodine allergies.
Minimally invasive lumbar decompression procedure (MILD)
- Spinal stenosis causes mobility restrictions and low-back pain.
- Small laminotomy to thin the ligamentum flavum.
- These procedures partially thin the ligamentum flavum as compared to surgical decompression that completely removes the ligament and bony elements.
Vertebroplasty
- Treats vertebral compression fractures through the injection of polymethylmethacrylate (PMMA).
Kyphoplasty
- Treats vertebral compression fractures involves inserting a ballon before the injection of cement.
- The balloon opens the space up more and allows for a thicker cement mix. Leakage of cement is a risk for both vertebroplasty and kyphoplasty, however, is less for kyphoplasty because of the cement mixture.
Spinal cord stimulation (SCS)
- Involves gate control theory, neurotransmitter modulation and suppression of sympathetic activity, with antidromic activity and supraspinal mechanisms.
- Increases large nerve fiber input
  - This “closes” the gate at the substantia gelatinosa of the dorsal horn of the spinal cord.
- Increased GABA and decreased glutamate and aspartate.
- Approved for low back and leg pain, failed surgical attempts, complex regional pain syndrome, and diabetic neuropathy.
- More favorable for peripheral neuropathic pain than for nociceptive, central, or mixed pain conditions.
Peripheral nerve stimulation
- Electrical stimulation of a peripheral nerve can treat neuropathic pain.
Intrathecal drug delivery (IDD)
- Opioids and other analgesics to be deposited near the spinal cord receptors.

OTHER

Scoliosis
- Leads to restrictive lung disease.
- Prolonged ventilator dependency is likely if the preoperative vital capacity is 30% less than predicted.
- May require a DLT if the surgery is above T8 in the lateral position.
- Surgery when Cobb angle exceeds 50^o thoracic or 40^o
Spinal cord monitoring (SCM) is mandatory for all surgeries in which the spinal cord is at risk of injury. 3 main methods:
- Wake-up test
- Somatosensory evoke potential (SSEP)
  - Dorsal column pathways of proprioception and vibration, supplied by the posterior spinal artery.
- Motor evoked potential (MEP)
  - Supplied by the anterior spinal arter
Rhizotomy
- Procedure that alleviates pain and muscle spasms by preventing the pain signals reaching the brain from nerve roots in the spinal cord.
- The anterolateral system carries sensations, such as pain, temperature, touch, etc. If nerve lysis is performed, loss of these sensations would be lost on the opposite (contralateral) side.
- The dorsal lemniscal system is responsible for touch, pressure, and position sensations. When a nerve root is lysed, these sensations would be lost on the same (ipsilateral) side.

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Orthopedic

ARTHROSCOPIC

Hypotensive bradycardic episodes (HBE) can occur in shoulder arthroscopy and the proposed causative mechanism is the Bezold-Jarisch reflex (BJR).
Positioning and prevention of nerve injuries are the key for orthopedics.

CLOSED REDUCTION

Can MAC these patients or general anesthesia via IV or inhalational.

FRACTURES

The most common fracture site that can lead to acute extremity compartment syndrome is the tibia.
- Normal compartment pressures are < 10 mm Hg.
- Risk of injury occurs when compartment pressures are > 30-50 mm Hg
- MAP – compartment pressure = > 70 mm Hg
- Definitive treatment is fasciotomy

TOTAL JOINT REPLACEMENTS/ARTHOPLASTY

Tranexamic acid (TXA) is recommended to be administered 15 minutes before incision in a hip arthroplasty.
Treatment for bone cement implantation syndrome (BCIS) during a total hip arthroplasty includes hemodynamic support, like crystalloid and vasopressor boluses.
- CV collapse resembles right-heart failure.
- Rapid CO₂ decrease is the first sign under general anesthesia for BCIS.
- Under regional, first signs dyspnea and altered sensorium.
Both fat embolism syndrome and bone cement implantation syndrome can cause dyspnea and altered mental status.
The leading cause of death in patients undergoing total hip replacement is pulmonary embolism. Arterial hypoxemia with hypocapnia characterizes a pulmonary embolus during hip surgery.
Fat embolism can occur with a long bone fracture or as the result of a trauma event. Small pulmonary arterioles are occluded by bone marrow fat. Indicators of a fatty embolus include decreased oxygen tension, lethargy or confusion, petechial hemorrhages, and fat in the urine and sputum. Petechiae is a strong indicator of fat embolism, especially on the upper extremities, chest, axilla, and conjunctiva.

HAND/FOOT PROCEDURES

Tourniquet precautions
Positioning precautions
Anesthesia: ankle block, MAC, or general

OTHERS

The primary anesthetic concern in patients with rheumatoid arthritis is atlantoaxial joint subluxation.
When the patient is prone, the head should be supported by a foam headrest with mirror attachment so that the eyes can be checked and documented every 20 minutes.
Postoperative vision loss (POVL) results from retinal vascular occlusion and ischemic optic neuropathy. POVL occurs when direct pressure on the eye results in occlusion of blood flow (prone positioning).
The generally accepted time limit for tourniquets is 120 minutes.
- Myoglobinemia can occur when the tourniquet is deflated.

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Perineal and Pelvic Procedures

Lithotomy is the most common position used for these procedures. Improper padding or positioning can lead to nerve damage.
Obturator reflex is not blocked by regional anesthesia, only neuromuscular blockers.

GYNECOLOGIC

Vagal reflex.

GENITOURINARY

Significant amounts of fluid (> 2 L) can enter the circulation and lead to TUR syndrome in TURP, TURBT, cystoscopy, ureteroscopy, percutaneous nephrolithotomy, and laser vaporization of the prostate.

TURP

Transurethral resection of the prostate involves a resectoscope that can cut and cauterize prostatic tissue to be removed.
- The use of lasers, instead of electrocautery, does not require a nonconductive fluid. This helps to avoid complications due to hypo-osmolarity and solute toxicity. Also, the amount of fluid needed for irrigation is less which reduces the systemic absorption.
Risk factors of increased absorption:
- Number and size of open venous sinuses
- Prostate capsule is disrupted surgically
- Extended resection duration
- Irrigation fluid has a high hydrostatic pressure
- Lower venous pressure when the irrigation and blood meet
Regional anesthesia has the advantage of an awake patient which can help identify TURP syndrome or bladder perforation. Also, regional anesthesia reduces postoperative venous thrombosis compared to general anesthesia. Evaluation of mental status in the awake patient is the best monitor for detection of early signs of the TURP syndrome and bladder perforation.
Due to the irrigation used, hyponatremia is common but rapid treatment can cause central pontine myelinolysis which results in serious permanent neurological sequelae. Hypertonic saline may be indicated in markedly symptomatic patients with hyponatremia.
TURP syndrome with glycine can cause hyperammonemia.
Hyperglycinemia can cause vision loss.
Spinal blockade level should be at T10.
Movement of a patient’s leg caused by electrocautery during TURP is due to stimulation of the obturator nerve.
During a TURP with regional anesthesia, the patient develops abdominal pain and sudden nausea/vomiting. The likely cause is bladder perforation.
When TUR syndrome is suspected intraoperatively, the surgeon is immediately notified. Treatment of acute hyponatremia with Na⁺ < 120 mEq/L should be treated with hypertonic saline 3% at 100 mL/hr. Chronic hyponatremia is corrected at 0.5 mEq/L/hr but there is no established rate for acute.

UROLITHIASIS

Patients with voided difficulties from spinal cord injuries/paralysis are at risk of autonomic hyperreflexia. Both regional and general anesthesia can block the afferent stimulation that is responsible.
Procedures for kidney stones:
- Shock wave lithotripsy, percutaneous nephrolithotomy, ureteroscopy, and pyelolithomy.
Lithotripsy
- High-energy and repetitive shocks are localized over a stone to break it into tiny fragments that are easily passed.
- The shock waves are timed for 20 ms after the R wave (during ventricular refractory period).
- Patients with pacemakers or internal cardiac defibrillators (ICD) are at risk of developing arrhythmias.
- For those patients with low heart rates or beta blocked, the surgeon may request glycopyrrolate to speed the procedure.

Anal/rectal

Positioning

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Vascular (open Versus Endovascular)

CAROTID

Preoperative
- Most strokes are ischemic rather than hemorrhagic and the mechanism is usually embolic instead of occlusive.
  - TIAs are focalized neurologic deficits lasting less than 24 hours and leave no residual deficit.
- Surgery is indicated when internal carotid artery stenosis is severe (> 70-80%). As the stenotic lesion lessens, medical management can be just as effective.
- The most common underlying pathophysiologic mechanism for cardiovascular disease is atherosclerosis.
- The most common coexisting medical condition in the patient undergoing CEA is hypertension.
- Surgical intervention is warranted for symptomatic patients within 2 weeks of an event, e.g. TIA.
Intraoperative
- An induction with thiopental is appropriate for a patient undergoing carotid endarterectomy with known cerebrovascular disease.
- Continuous arterial monitoring (commonly via radial) is essential in the management of these patients.
- Heparin is given before the carotid artery is clamped.
- The best way to monitor a patient’s neurologic status during a carotid endarterectomy is an awake patient with a cervical plexus block. The goal of any neurological monitoring is to select those patients who need a shunt versus those who do not.
- Intraoperative monitoring
  - Electroencephalography (EEG) is the most common monitor for carotid surgery and monitors cortical functioning. Normal blood flow is 50 mL/min/100 g of brain tissue. EEG shows symptomatic hypoperfusion at 15-18 mL/min/100 g and cell death at 10-12 mL/min/100 g or below.
  - SSEP monitoring reflects deep brain structures through the electrical stimulation of nerves to monitor their response.
    - Median and tibial nerve monitoring is common.
      - Median nerve decrease identifies the middle cerebral artery.
      - Tibial nerve decrease identifies the anterior cerebral artery.
    - MEPs are very reliable but neuromuscular blockade affects monitoring.
    - Transcranial doppler (TCD) measures the maximum velocity of blood flow through the middle cerebral artery. It is more specific for microembolic events than other monitors. Also, it can measure the blood flow after carotid clamp or stent placement to ensure adequate blood flow is achieved.
    - Carotid stump pressure measures the pressure distal to the carotid clamp. Measuring stump pressures during CEA surgery reflects perfusion to the circle of Willis. A carotid stump pressure of less than 40-50 mm Hg reflects neurologic hypoperfusion and is a criterion for shunt placement.
  - The reason for the postoperative carotid endarterectomy patient’s inability to increase ventilation in response to a decrease in P_aO₂ is bilateral loss of carotid body function.
  - Hypoperfusion due to carotid cross-clamping and incomplete circle of Willis causes cerebral ischemia.
  - A shunt placed in the carotid artery can bypass the clamp and provide cerebral perfusion. Even though commonly used, a shunt is only beneficial if inadequate blood flow is the case of neurologic dysfunction.
  - ETCO₂ should remain normal as hypocapnia could lead to vasoconstriction and hypercapnia could increase blood flow to normal vessels.
  - Hypothermia helps to decrease cerebral oxygen demands but care should be taken to prevent shivering.
- Postoperative
  - Most common complication of a CEA is myocardial infarction.
  - Elective surgery should be postponed for 6 weeks after a stroke. 4-6 weeks after a cerebrovascular accident is required to allow areas of ischemia and the blood-brain barrier to normalize.
  - There is a 6% chance of stroke postoperatively.
  - Hypertension is the most common hemodynamic parameter and can precipitate MI, CVA, and/or death.
  - Postoperative respiratory compromise can result from nerve damage, carotid body manipulation, and wound hematoma.
- CAROTID ARTERY STENTING
  - Minimally invasive
  - Requires little to no sedation
  - Able to continuously monitor neurologic status

THORACIC

Prolonged cross-clamping of the thoracic aorta may lead to paraplegia due to decreased (or absent) blood flow through the artery of Adamkiewicz.
- To prevent spinal cord ischemia, the best approach is to limit clamp time, normalize cardiac function, and increase perfusion pressure.
- Spinal cord perfusion is directly affected by MAP or CSF pressure. Because increases in MAP after cross-clamp release is incredibly difficult, a CSF drain may be utilized to lower the pressure to < 12 mm Hg so that perfusion is optimized.
Postoperative paraplegia is associated with thoracic aortic cross-clamping.
After cross-clamping the thoracic aorta, blood flow to the lower extremities is likely halted. Because of the lack of perfusion below the clamp, metabolism switches to anaerobic pathways, resulting from a lack of oxygen availability.
Crawford is used to classify thoracoabdominal aortic aneurysms.
DeBakey Type I is an aortic dissection that originates in the ascending aorta and extends to the aortic arch and descending aorta.
Type A aortic dissections
- Involves the ascending aorta and may extend into the aortic arch.
- Most likely to rupture and requires surgery.
The most important intervention to prevent postoperative renal failure is to maintain intravascular volume. However, there is no definitive treatment/prevention method.

ABDOMINAL (including RENAL)

Aneurysm
- Abdominal aortic aneurysm (AAAs) is occurs 9 times more often than thoracic. The most important factor related to rupture is the size of the aneurysm.
- Surgery is indicated when AAAs are ≥ 5 cm for men or ≥ 5.0 cm for women.
- AAAs can be:
  - Infrarenal (overwhelming majority)
  - Juxtarenal
  - Suprarenal
- Cross-clamping
  - Generally, prior to clamping the patient is kept hypovolemic. Upon clamping, vasodilating infusions are needed.
  - The level of the clamp determines how much hemodynamics and blood flow are affected. Supraceliac occlusion leads to the most morbidity when compared to suprarenal and infrarenal occlusion.
  - Heart rate is minimally affected but cross-clamping greatly increases the SVR.
  - Prior to clamping, heart rate is decreased with esmolol.
  - Hypertension is treated with nitroprusside, nitroglycerin, or nicardipine.
  - When the abdominal aorta has been cross-clamped, there is an increased accumulation of lactate below the clamp.
  - 2 separate unclamping events:
    - Unclamping so reperfusion can occur to the proximal anastomosis. This does not result in much hemodynamic change.
    - When the clamp is released after the distal anastomosis is complete, there is a significant drop in SVR.
  - After unclamping the aorta, hypotension is expected.
  - When the abdominal aortic clamp is released during aneurysm repair, minute ventilation should be increased to prevent hypercarbia to the ischemic areas distal to the clamp.
- Dissection
  - A tear in the intimal layer of the arterial wall that creates a false lumen, propagated by pulsatile blood flow.
  - Next most common site is past the left subclavian artery, close proximity to the ligamentum arteriosum.
- ENDOVASCULAR AORTIC REPAIR (EVAR)
  - Treatment of choice over open repair
  - Minimally invasive
  - Higher likelihood of re-intervention than open
  - Requires lifetime surveillance
  - Most common reason for re-intervention is endoleak.
    - Blood flow into the aneurysm sac outside of the stent graft.

TYPES OF ENDO LEAKS

Type 1	Leak is at the proximal or distal graft attachment site.
Type 2	Aneurysm grows, not because of a leak, due to retrograde flow that is filling the sac. Lumbar or inferior mesenteric arteries are the culprit.
Type 3	Graft defect from a fabric tear or disconnection of the modular overlap.
Type 4	Graft wall porosity.
Type 5	No identifiable cause for the increase in aneurysm size.

Types 1 and 3 require re-intervention.

EXTREMITY

OCCLUSIVE DISEASE

3 indicators for surgery:
- Intermittent claudication
- Ischemic rest pain
- Gangrene
Aortoiliac occlusive disease (AIOD) develops in the distal aorta or proximal common iliac arteries that causes claudication in the buttocks or hip.
Decreased blood flow from atherosclerosis and increased oxygen demand during periods of walking/exercise leads to the pain described with intermittent claudication.
The blood flow can decrease to a point where ischemia develops even at rest and results in gangrene.
AIOD treatment

REPAIR TYPE	DIRECT	EXTRA-ANATOMIC
SURGICAL SITES	Aortoiliac Aortofemoral	Axillary-femoral Femoral-femoral
PATENCY RATE	>80%	55-80%
MORBIDITY/MORTALITY	Greater	Less
ANESTHESIA MGMT	-Like open AAA -Less hemodynamic instability with clamping than AAA -Invasive central monitoring and arterial BP	-No aorta clamp/unclamp; instead axillary/femoral -Less cardiac alterations than direct approach -Arterial BP monitored on opposite side; no invasive

Vascular Access

THROMBOEMBOLIC PREVENTION

Risk factors:
- Sedentary lifestyle
- Cancer
- Oral contraceptives/Estrogen therapy
- Pregnancy
Factor V Leiden (FVL)
- Congenital mutation
- Normally, activated Protein C prevents clotting
- FVL is essentially resistant to the normal action of activated Protein C
- Factor V activity is increased leading to thrombus formation
Protein C deficiency
- Protein C is an inhibitor and has a 6 hour half-life
Antiphospholipid antibodies (APLA)
- Hypercoagulable state in antiphospholipid syndrome
Therapeutics
- Warfarin
  - PT/INR
  - Factors II, VII, IX, and X
  - INR therapeutic range: 2-3
  - Reversal: vitamin K
- Heparin
  - PTT
  - Therapeutic range: 1.5 – 2.5 times normal
  - Reversal: protamine
- Direct oral anticoagulants
  - Dabigatran
    - Direct thrombin inhibitor (DTI)
  - Rivaroxaban, edoxaban, apixaban, and betrixaban
    - Inhibit factor Xa

SURGICAL MANAGEMENT OF PORTAL HYPERTENSION

The hydrostatic pressure in the portal vein is usually < 10 mm Hg. When fluid surpasses the removal capabilities of the lymphatics, abdominal ascites develops.
4 major collateral sites develop due to portal hypertension and lead to ascites, esophageal varices, hemorrhoids, and GI bleeding.
Variceal blood loss can be treated medically with vasopressin, somatostatin, and propranolol along with blood transfusion.
Endoscopic ligation can stop the bleeding from esophageal varices.
Percutaneous transjugular intrahepatic portosystemic shunts (TIPS) reduces portal hypertension and bleeding.

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Non - Operating Room Anesthesia (NORA)

DIAGNOSTIC IMAGING AND RADIOLOGY

X-RAYS AND FLUROSCOPY

Hazards of ionization radiation
- Limit radiation time
- Inverse square law- increase distance from x-ray
- Lead aprons to block x-ray

IV CONTRAST

Contrast is given to enhance radiologic imagery.
Contrast can cause kidney damage so baseline values must be obtained first. Chronic kidney disease is the most important factor. To help prevent kidney damage, ensure adequate hydration and urine output.
Allergic reactions can occur with IV contrast. Hypersensitivity can result in mild or severe reactions. Severe reactions can be life-threatening. Gadolinium contrast can be used as an alternative.

ELECTROCONVULSIVE THERAPY

Helps manage depression, mania, and affective disorders. These procedures are 3 times a week initially for 2-4 weeks and then maintenance therapy can be performed weekly or monthly.
ECTs produce a seizure and an accompanying cardiovascular response is seen.
Methohexital is the gold standard; however, several medications can be used.
Cerebral blood flow (CBF) and ICP increase.
Patients report retrograde amnesia.
Immediate parasympathetic response followed one minute later by a sympathetic response.

INTERVENTIONAL RADIOLOGY

ANGIOGRAPHY

Performed via femoral artery or vein.
The gantry goes in and out to track vessels and catheters. Extensions are needed.

INTERVENTIONAL NEURORADIOLOGY

Occlusive
- Cerebral aneurysms and AVMs
Opening
- Management of acute thromboembolic stroke and postsubarachnoid hemorrhage vasospasm.

COMPUTED TOMOGRAPHY (CT)

Sedation is sometimes needed to alleviate anxiety.

RADIOFREQUENCY ABLATION

Treats primary and metastatic tumors in the liver, lung, adrenal gland, breast, thyroid, prostate, kidney, and spleen.
A high-frequency alternating current is used to generate a localized heat source directly into the tumor causing coagulative necrosis and tumor cell death while avoiding injury to the adjacent tissues.

TRANSJUGULAR INTRAHEPATIC PORTOSYSTEMIC SHUNT (TIPS)

A percutaneous catheter is inserted in the IJ and directed to the liver to create a connection between the hepatic portal and systemic circulations.
Treats portal hypertension, reduces esophageal bleeding, and helps control ascites.

MAGNETIC RESONANCE IMAGING (MRI)

Metal objects must be removed from the vicinity. Patients with cardiac pacemakers and/or cerebral aneurysm clips should not undergo scanning.
Considerable noise produced by the machine and claustrophobia are concerns.

CARDIOLOGY

These procedures are routinely done with light sedation or MAC anesthesia. However, patients that are hemodynamically unstable, likely to obstruct, difficult to sedate, or anxiety may require assistance.
Interventional stent placement
Ventricular assist devices
- Impella improves coronary perfusion and cardiac output.
Closure of septal defects:
- PREVENT AIR BUBBLES IN IV LINES BECAUSE IT CAN REVERSE SHUNTS
Patent foramen ovale
Atrial septal defect
Paravalvular leak
Ventricular septal defect

Alcohol septal ablation
Transcatheter aortic valve replacement
Mitral transcatheter edge-to-edge repair
Left atrial appendage occlusion
- The left atrial appendage is a source of clot formation with a-fib.
Electrophysiology
- Studies taking 3 – 4 hours may be too uncomfortable for a patient to lie completely without sedation. Also, lead extractions require general anesthesia with invasive monitoring.
Cardioversion and TEEs
- Before cardioversion, TEE is used to rule out a clot.

RADIATION THERAPY

Common for children with cancer
Uses highly tissue-targeted or total body irradiating (TBI) x-ray doses.
Proton beam therapy provides a more specific dose with less adjacent tissue damage.

ENDOSCOPY

EGDs and colonoscopies can be performed with versed and Demerol by an RN under the supervision of the endoscopist or with propofol by an anesthesia provider.
EGDs are very stimulating and can lead to coughing/gagging, vomiting, laryngospasm, etc. Bite blocks are placed before the procedure starts.
Colonoscopies examine the inner lining of the large intestine, remove precancerous polyps, identify cancers lesions requiring surgery, etc. The patient may experience a vagal response as the endoscopist passes through the transverse colon and stimulates the diaphragm.

REFERENCE: Barash Chapter 33

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Robotic / Laparoscopic Surgery

ROBOTIC

Advantages over laparoscopy:
- Better view and more range of motion
- Better surgical outcomes
- Lower complication rates
- Shortened hospital stay

LAPAROSCOPY

Laparoscopy provides many advantages over traditional laparotomy, including:
- Improved mobility and quicker to return to normal activities
- More cosmetic
- Less postoperative pain
- Shorter recovery time
Laparoscopy can also increase PONV and patients often experience referred shoulder pain due to diaphragmatic irritation.
Carbon dioxide is the gas that is used to insufflate the abdomen for the pneumoperitoneum because it is highly soluble in blood and can be removed quickly. Also, it is nonflammable so electrocautery can be used during pneumoperitoneum.
Cardiovascular effects:
- Increased
  - MAP
  - Myocardial oxygen demand
  - Cardiac index
  - SVR/PVR
  - Preload
- Patient positioning and older age can alter these changes.
- Pneumoperitoneal pressures ≥ 15 mm Hg exaggerate these changes.
Respiratory effects:
- Increased
  - Diaphragm
  - Pleural pressure
  - Airway pressure
  - Lung resistance
  - Risk of endobronchial intubation
  - CO₂ absorption
  - V/Q mismatch
  - Hypoxia
- Decreased
  - Lung compliance
- Anesthesia management
  - GETA, muscle relaxation, and controlled ventilation
  - Nitrous oxide is generally avoided because it can diffuse into air-filled spaces, increase risk of PONV, and is known to support combustion.
  - Tidal volumes of 6 – 8 mL/kg ideal body weight and PEEP 5 – 10 cm H₂O are lung protective strategies.
  - PEEP improves V/Q mismatching, hypoxia, and hypercarbia but also decreases preload.
  - Fluid replacement due to evaporative loss is lower in laparoscopy than with open procedures

COMPLICATIONS

Venous gas embolism
- Establishing a pneumoperitoneum carries the highest risk of laparoscopy because of the potential for CO₂ embolism and hemorrhage. Other possible injuries include pneumothorax, pneumomediastinum, and pneumopericardium.
- Symptoms:
  - Tachycardia and arrhythmias
  - Hypotension
  - Hypoxemia and low ETCO₂
  - Mill wheel murmur
- TEE is the most sensitive method for detection. The gas embolus would appear as a near white-out in the right heart.
- The patient should be placed into left lateral decubitus in the event of a gas embolus during laparoscopy. Support includes basic hemodynamic up to ACLS. A CVL can be placed to withdraw the gas.
Risk factors for subcutaneous absorption of carbon dioxide during laparoscopy:
- Multiple attempts at abdominal entry
- Procedure longer than 3.5 hours
- Increased number of ports
- Lower BMI
- Older age

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Other Surgical Procedures

TRAUMA

AIRWAY

Airway management involves a rapid-sequence induction with manual in-line stabilization for tracheal intubation.
Even with known cervical injury, oral tracheal intubation can be performed as safely as the nasal route.
The gum elastic bougie has been used with great documented success in trauma airways.
It is the provider’s choice/discretion on whether to use direct laryngoscopy or video laryngoscopy as the current evidence shows no difference in attempts or time required.
Ventilatory strategies involve lower tidal volumes (6 mL/kg) to limit possible lung injury.

RESUSCITATION

For those hypotensive trauma patients, a crystalloid bolus has been proven to increase blood pressure and decrease mortality. Vasopressors in a hypotensive setting (as first-line treatment) and preloading crystalloid in a normotensive patient is not indicated.
Resuscitation is centered on the administration of “hemostatic” blood products.
Massive transfusion is:
- 10 units of whole blood in 24 hours
- > 150 mL/hr of blood loss
- Transfusion of > 5 units of whole blood in 3 hours
Transfusion ratios of PRBCs, FFP, and platelets of 1:1 improved outcomes.
The ideal resuscitative fluid for hemorrhagic shock is blood.

NEUROLOGIC

The main cause of death in trauma is neurologic injury. Hypotension and hypoxemia can have detrimental effects with traumatic brain injury (TBI). Therefore, maintaining cerebral perfusion pressure is vital.
No improvements or benefits seen with decompressive craniectomy, ventriculostomy catheter, or steroids.
Mannitol has been proven to decrease ICP but can lead to renal failure. Hypertonic saline dodges the renal risk but must be given in a central line.
Post-traumatic seizure prophylaxis for 7 days after the injury is recommended. Both phenytoin and levetiracetam are appropriate.

BURNS

Initial therapy of burn victims focuses on fluid resuscitation and airway management.
The burn patient will first experience a loss of vascular and endothelial integrity.
Inhalational injury to a burn patient’s airway greatly increases mortality.
The hallmark in the reduction in cardiac output after a major injury is 24 hours.
The initial phase of a major burn injury results in third-spaced edema and the

inflammatory response (burn shock). After 24-72 hours, the hypermetabolic phase begins where the major mediators are catecholamines and corticosteroids.

A major burn is:
- A 2^nd -degree burn involving more than 10% of the TBSA in adults or 20% at extremes of age;
- A 3^rd -degree burn involving more than 10% of the TBSA in adults;
- Any electrical burn;
- A burn complicated by smoke inhalation.
Succinylcholine is OK in burn patients until 24 hours after the incident.
- Cholinergic receptor up-regulation occurs after a burn injury, with proliferation of acetylcholine receptors throughout the muscle membrane.
- Succinylcholine can cause potassium release from the entire muscle membrane rather than from discrete endplate junctions, leading to hyperkalemia and cardiac arrest.
The dose of nondepolarizing muscle relaxants in burn patients is increased.
- Up-regulation of acetylcholine receptors.
- Massive fluid shifts producing significant changes in volume of distribution.
- Qualitative decrease in receptor sensitivity.

CARBON MONOXIDE

Carbon monoxide poisoning is treated with 100% oxygen for 6 hours or until the carbon monoxide hemoglobin level is 5%.
Carbon monoxide has a 200 times stronger bond with hemoglobin than does oxygen.
The pulse oximeter in a patient with carbon monoxide poisoning will be falsely elevated.

ORGAN TRANSPLANTS (including MANAGEMENT OF POSTTRANSPLANT PATIENT FOR NONTRANSPLANT SURGERY)

Living donors that donate a kidney or liver lobe must be without major cardiac, pulmonary, neurologic, or psychiatric disease.

LIVER

Liver transplantation 3 phases:
- Dissection
- Anhepatic
- Neohepatic (start is the reperfusion of the graft)

LUNG

Lung recipient guidelines:
- Chronic, end-stage lung disease
- High risk of death (> 50% in 2 years)
- High chance of survival with a successful transplant
Single lumen ETTs are indicated for en bloc double-lung transplant using bypass but otherwise a DLT is needed for lung isolation.
Once the pneumonectomy is complete, the surgeon sutures in the donor lung. Anastomosis is checked with TEE and methylprednisolone is given prior to reperfusion. Once transplant complete, FiO₂ is titrated down to 40-50% and a goal of SpO₂ > 92. Perfadex (dextran solution) is given to improve graft function.
Primary graft dysfunction is allograft dysfunction within 72 hours. Grade 3 (out of 3) is associated with the worst mortality.

RENAL

These recipients are often anemic.
To maintain blood flow, volume expansion is key rather than vasopressors.

HEART

Because medical management has improved, many patients are presenting for transplant with worsened underlying conditions. Left ventricular assist devices and/or mechanical circulatory support devices are seen more often during transplantation.
The most common indication for heart transplantation is nonischemic cardiomyopathy.

MANAGEMENT FOR NONTRANSPLANT SURGERY

Because the patient is on immunosuppressives, infections should be treated early and aggressively.
NSAIDs should be avoided because of renal dysfunction, either due to their history or from immunosuppression medications.
Patients are on chronic steroids as well.
A thorough preoperative evaluation is key in assessing current organ function and how it relates to the medications that can be used.
Nasal intubation should be avoided because it can introduce normal flora and increase infection risk.
Lung transplant recipients with anastomosis at the trachea are denervated below that suture line. Therefore, they are at increased risk of developing pneumonia because their cough reflex is greatly diminished.
As with lung recipients, transplanted hearts are denervated and will not respond to indirect cardiac medications.
- With epinephrine and norepinephrine, alpha stimulation is much less than beta.
- ECG may show 2 P waves. Interestingly the native P wave may still be present but does not stimulate the heart. The 2^nd P wave is the transplanted heart’s electrical activity.

ORGAN PROCUREMENT

Brain death means all brain functions have irreversibly stopped. All possible corrective measures that may mask the absence of brain activity have been explored and ruled out. This is important because each state has different legal and medical brain death criteria.
Two stages:
- Initial autonomic storm due to a catecholamine surge.
- Profound hypotension and hypovolemia due to endocrine and sympathetic system failre.
Goals for resuscitation:
- MAP > 60 mm Hg
- UOP 1 mL/kg/hour
- EF 45%
- Minimal pressors (dopamine or vasopressin)

LASER PROCEDURES

LASER- light amplification by stimulated emission of radiation
Benefits:
- Specificity in intended tissues
- Blood loss and edema formation are reduced
- Healing time is quicker
- Surrounding tissues are less affected
The fire hazard can be greatly reduced or eliminated by removing the oxygen source and ETT. The first step in an airway fire is to simultaneously stop ventilation and extubate the patient.

CO₂ LASER

CO₂ laser is the most common.
It is absorbed by the tissues.
Eye protection is vital for the patient and OR staff because the eyes are vulnerable to stray laser beams.
- CO₂ only causes corneal damage because of the laser’s penetration (0.01 mm).
- For comparison, the neodymium-yttrium-aluminum-garnet (Nd: YAG) laser can damage the retina and produce scarring because of deeper penetration.
Damp towels in the field help to absorb the laser to prevent damage and also prevent fire.
FiO₂ should be at the lowest possible setting because oxygen supports combustion.
The ETT cuff can be filled with sterile saline. If the cuff is accidentally ruptured by a spark, the saline can help extinguish.
The staff should wear high-efficiency masks to protect from the laser plume created by a CO₂ laser used to remove respiratory papillomatosis.
As wavelength increases, the energy of the laser light decreases. There is increased absorption by water and decreased tissue penetration and coagulation. Corneal damage is more likely with longer wavelength lasers (CO₂ laser) and retinal damage is more likely with shorter wavelength lasers (YAG laser).