III. GENERAL PRINCIPLES OF ANESTHESIA

PREOPERATIVE ASSESSMENT AND PREPARATION OF THE PATIENT

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PREOPERATIVE ASSESSMENT AND PREPARATION OF THE PATIENT

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Preoperative Assessment and Preparation of the Patient

Preoperative Assessment and Preparation of the Patient

  • Independent risk factors for difficult mask ventilation show beard poses the greatest risk to difficult ventilation, followed in order by BMI ≥ 26, edentulous, age > 55, and history of snoring.
  • Factors associated with difficult mask ventilation include obesity, age, macroglossia, beard, lack of teeth, history of snoring, increased Mallampati grade and decreased thyromental distance.
  • The adult should be able to open his/her mouth so that there is a 40 mm distance (two large fingerbreadths) between upper and lower incisors.
  • Mallampati 1: soft palate, fauces, uvula, anterior & posterior tonsillar pillars.
  • Mallampati 3: soft palate, base of uvula.
  • Temporomandibular joint mobility is best evaluated by having the patient open his/her mouth as wide as possible. Arthritis is the usual cause of temporomandibular joint immobility. Condylar head motion correlates with TMJ mobility.

 

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NPO Guidelines

CLEAR LIQUIDS

2 HOURS

BREAST MILK

4 HOURS

INFANT FORMULA

6 HOURS

NONHUMAN MILK

6 HOURS

LIGHT MEAL

6 HOURS

FRIED FOODS, FATTY FOOD, OR MEAT

8 HOURS

  • Body mass index (BMI)
    • (Body weight in pounds) / (Height in inches2) x 703

ASA / EXPLANATION

ADULT EXPLANATION

OB EXPLANATION

PEDIATRIC EXPLANATION

1/Normal

No smoking

Minimal drinking

Healthy

 

Healthy

Normal BMI

2/Mild systemic disease

Current smoker, social drinker, obesity (BMI ≤40), well-controlled DM/HTN, mild lung impairment

Normal pregnancy; well controlled HTN, preeclampsia without severe features, diet-controlled gestational DM

Congenital heart disease without symptoms, well controlled dysrhythmias, asthma (controlled), NIDDM, OSA, mild autism

3/Severe systemic

Poorly controlled DM or HTN, COPD, BMI > 40, active hepatitis, alcohol abuse, pacemaker, moderately ↓ EF, ESRD with regular dialysis, history of MI (> 3 months), CVA, or CAD/stents

Preeclampsia with severe features, gestational DM with complications or high insulin requirements, a thrombophilic disease requiring anticoagulation.

Uncorrected stable congenital cardiac abnormality, acute asthma, poorly controlled epilepsy, IDDM, morbid obesity, malnutrition, severe OSA, oncologic state, renal failure, muscular dystrophy, cystic fibrosis, history of organ transplantation, brain/spinal cord malformation, symptomatic hydrocephalus, premature infant PCA <60 weeks, autism with severe limitations, metabolic disease, difficult airway, long term parenteral nutrition. Full term infants <6 weeks of age.

4/Severe systemic disease, constant threat to life

Recent (<3 months) MI, CVA, TIA or CAD/stents, ongoing cardiac ischemia or severe valve dysfunction, severe reduction of ejection fraction, shock, sepsis, DIC, ARD or ESRD not undergoing regularly scheduled dialysis

Preeclampsia with severe features complicated by HELLP or other adverse event, peripartum cardiomyopathy with EF <40, uncorrected/decompensated heart disease, acquired or congenital.

Symptomatic congenital cardiac abnormality, CHF, active sequelae of prematurity, acute hypoxic-ischemic encephalopathy, shock, sepsis, disseminated intravascular coagulation, AICD, ventilator dependence, endocrinopathy, severe trauma, severe respiratory distress, advanced oncologic state.

5/Moribund, not expected to survive without surgery

Ruptured abdominal/thoracic aneurysm, massive trauma, intracranial bleed with mass effect, ischemic bowel in the face of significant cardiac pathology or multiple organ/system dysfunction

Uterine rupture

Massive trauma, intracranial hemorrhage with mass effect, ECMO, respiratory failure/arrest, malignant HTN, decompensated CHF, hepatic encephalopathy, ischemic bowel or multiple organ/system dysfunction.

6/Brain dead for organ harvest

   

 

  • The most critical factor to maintain normothermia is the operating room temperature.
  • The following patients are inappropriate candidates for ambulatory surgery:
    • Major blood loss or major surgery
    • ASA III and IV patients who require complex or extended monitoring or postoperative treatment
    • BMI > 40 with OSA or other significant respiratory impairment
    • Complex pain management
    • Significant fever, wheezing, nasal congestion, cough, or other symptoms of a recent upper respiratory infection
    • Malignant hyperthermia or family history
    • Uncontrolled seizure activity
    • Acute substance abuse
    • Active infection
    • Uncooperative or unreliable patients
    • Patients who have no responsible adult at home during convalescence.
  • Preoperative incentive spirometry is based on teaching the patient to mobilize secretions and to increase lung volume.

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