Airway Management in the Morbidly Obese Patient with Difficult Airway and/or Full Stomach

Educational Objectives

The goal of this program is to improve airway management in morbidly obese patients. After hearing and assimilating this program, the clinician will be better able to:

1. Minimize risk for aspiration in obese patients undergoing surgery.
2. Identify risk factors for difficult airway in patients with obesity.

Summary

Obesity and gastric emptying: a study listed obesity as the strongest risk factor for gastroesophageal reflux disease (GERD), ahead of positive family history, previous or current smoking history, and alcohol consumption; incidence of GERD in patients with body mass index (BMI) ≥30 was 69%; patients with obesity have larger stomachs; antral volume is directly proportional to BMI; stomach should be empty after controlled fast; exceptions include patients with achalasia, Zollinger-Ellison syndrome, gastrointestinal stromal tumors, complicated surgical and medical histories, and symptomatic GERD; rate of gastric emptying is normal or accelerated in patients with obesity

Aspiration: speaker states Mendelson criteria of gastric volume <25 mL or <0.3 mL/kg and pH <2.5 are excessively cautious; suggests 0.7 mL/kg is a more reasonable threshold; morbid obesity is considered a risk factor for aspiration because of increased intra-abdominal pressure and increased incidence of hiatal hernia

Bariatric surgery at speaker’s institution: likely <1% of patients undergo rapid sequence induction (RSI); patients not given solid foods by mouth for 2 days; given sports drinks at midnight and 6:00 AM; standard of care is to use 3 antiemetic medications; use of opioid agents is minimized because of potential for opioid-induced nausea and vomiting; bariatric surgery is associated with more nausea than most other procedures because of disruption of the gastroesophageal antireflux mechanism, pneumoperitoneum, and short-term ileus; speaker proposes successful management of bariatric patients without RSI; suggests obese patients in general may not require RSI (does not apply to redo surgery or patients brought back to operating room [OR]); patients with torsion or obstruction after undergoing a surgical procedure on the gastrointestinal tract require RSI and probably evacuation of stomach

Bravo esophageal pH monitoring: allows quantification of the severity of GERD; involves monitoring esophageal pH for 48 hr; esophageal pH <4 for 4.4% of time on average day classified as GERD

Recommendations to reduce risk for aspiration in obese surgical patients: evaluate patients as early as possible, optimally 1 to 2 wk preoperatively; encourage patients with diagnosed or suspected obstructive sleep apnea (OSA) to wear continuous positive airway pressure (CPAP) or bilevel positive airway pressure (BiPAP) masks; wearing CPAP or BiPAP mask for 2 wk improves cardiopulmonary function; speaker recommends 2-day solid fast (liquids acceptable); patient should consume sports drink at midnight and 4:00 AM before surgery; use triple antiemetic therapy; for induction, maximize lidocaine, consider small amounts of midazolam, and minimize opioid drugs; corticosteroids in doses of 0.1 mg/kg total body weight effective for reducing nausea; replace volatile anesthetic agents with total intravenous anesthesia for maintenance; speaker uses regional blocks and multimodal analgesia; speaker cancels case if patient fails to stop smoking ≥2 wk preoperatively

Quantification of stomach contents: can quantify antral volume by ultrasonography with patient in right lateral decubitus position; speaker recommends postponement if patient has liquid or solid contents in stomach

Difficult airway in patients with obesity: morbid obesity is not necessarily associated with difficult airway; rate of difficult airway is much higher in patients with morbid obesity plus OSA; predictors for difficult mask ventilation and intubation in obese patients include OSA, high modified Mallampati score, increasing age, male sex, short neck, high Wilson score, and increased neck circumference; obesity epidemic in United States and Canada involves primarily adolescents and women; OSA patients are primarily middle-aged men

Location: De Jong et al (2015) found incidence of difficult intubation in obese patients is higher in the intensive care unit than in the OR; location is more important than BMI; data from American Society of Anesthesiologists (ASA) closed claims analysis show more airway issues outside of OR, particularly with non-OR anesthesia; about half of problems occurred in the gastrointestinal unit; higher BMI was identified as risk factor

Oxygenation: interventions to improve oxygenation during anesthesia and sedation can improve safety by reducing incidence of hypoxia

Markers for difficult airway: include increased neck circumference and craniofacial dysostosis; Prader-Willi syndrome is associated with obesity plus OSA

Workup of patient with OSA: consider phenotype; sleep study is hallmark test, particularly lowest saturation, longest apnea duration, mean overnight saturation, and oxygen desaturation index; polysomnography is useful for stratification and to improve all-cause outcome; neck and waist circumference are more important than BMI for predicting difficult airway; waist-to-hip ratio >1 in obese men or >0.85 in obese women indicates OSA

Maneuvers: options include 3 to 5 min of sedated CPAP and preoxygenation; duration of apnea without desaturation in obese patients is similar to that in pregnant patients

Further evaluation: STOP-Bang questionnaire is best ratified tool; can improve sensitivity by assessing venous bicarbonate; has highest methodologic validity; ASA developed ratified risk scoring system for OSA

Emergency airway: speaker recommends bougie-knife-6.0 cuffed endotracheal tube technique; Seldinger technique is falling out of favor but still has proponents

Readings

Benumof JL: Obesity, sleep apnea, the airway and anesthesia. Curr Opin Anaesthesiol 2004 Feb;17(1):21-30; Brodsky JB et al: Morbid obesity and tracheal intubation. Anesth Analg 2002 Mar;94(3):732-6; table of contents; De Jong A et al: Difficult intubation in obese patients: incidence, risk factors, and complications in the operating theatre and in intensive care units. Br J Anaesth 2015 Feb;114(2):297-306; Mahajan V et al: Comparative evaluation of gastric pH and volume in morbidly obese and lean patients undergoing elective surgery and effect of aspiration prophylaxis. J Clin Anesth 2015 Aug;27(5):396-400.

Disclosures

For this program, members of the faculty and planning committee reported nothing to disclose.

Acknowledgements

Dr. Samuels was recorded at the 73rd Postgraduate Assembly in Anesthesiology, held December 13-17, 2019, in New York, NY, and presented by the New York State Society of Anesthesiologists, Inc. For information about upcoming CME opportunities from the New York State Society of Anesthesiologists, Inc., please visit www.nyssa-pga.org. The Audio Digest Foundation thanks the speakers and the New York State Society of Anesthesiologists, Inc. for their cooperation in the production of this program.

CME/CE INFO

Accreditation:

The Audio- Digest Foundation is accredited by the Accreditation Council for Continuing Medical Education to provide continuing medical education for physicians.

The Audio- Digest Foundation designates this enduring material for a maximum of 0 AMA PRA Category 1 Credits™. Physicians should claim only the credit commensurate with the extent of their participation in the activity.

Audio Digest Foundation is accredited as a provider of continuing nursing education by the American Nurses Credentialing Center's (ANCC's) Commission on Accreditation. Audio Digest Foundation designates this activity for 0 CE contact hours.

Lecture ID:

AN622701

Expiration:

This CME course qualifies for AMA PRA Category 1 Credits™ for 3 years from the date of publication.

Instructions:

To earn CME/CE credit for this course, you must complete all the following components in the order recommended: (1) Review introductory course content, including Educational Objectives and Faculty/Planner Disclosures; (2) Listen to the audio program and review accompanying learning materials; (3) Complete posttest (only after completing Step 2) and earn a passing score of at least 80%. Taking the course Pretest and completing the Evaluation Survey are strongly recommended (but not mandatory) components of completing this CME/CE course.

Estimated time to complete this CME/CE course:

Approximately 2x the length of the recorded lecture to account for time spent studying accompanying learning materials and completing tests.