Spotlight Case

1. Spotlight Case Weighing in on Surgical Safety

2. Source and Credits • This presentation is based on the July 2010AHRQ WebM&M Spotlight Case • See the full article at http://webmm.ahrq.gov • CME credit is available • Commentary by:Jay B. Brodsky, MD, Stanford University Medical Center; Michael Margarson, MD, St. Richard’s Hospital, Chichester, UK • Editor, AHRQ WebM&M: Robert Wachter, MD • Spotlight Editor: Niraj Sehgal, MD, MPH • Managing Editor: Erin Hartman, MS

3. Objectives At the conclusion of this educational activity, participants should be able to: • Identify the comorbidities associated with obesity that place patients at higher risk for surgical complications • Understand elements of the STOP-BANG questionnaire that help screen patients for obstructive sleep apnea • Explain the most effective strategies for managing anesthesia and postoperative pain control in the obese patient • Appreciate the role of positioning to ensure safe outcomes for surgical patients with obesity

4. Case: Surgical Safety A 54-year-old man with diabetes mellitus, hypertension, and obstructive sleep apnea (OSA) was referred to an orthopedic surgeon after many years of left knee pain. Despite aggressive efforts with physical therapy and medications to treat his pain, the patient continued to experience increasing functional limitations.

5. Case: Surgical Safety (2) Although the patient tried to lose weight many times, his body mass index remained 40 kg/m2 (normal is approximately 19-25). After having a total knee replacement recommended, he was referred to a preoperative clinic for evaluation.

6. Background • Obesity is an increasing problem • Overweight is BMI > 25 • Obese is BMI > 30 • Morbid obesity is BMI > 40 • Obesity associated with many medical comorbidities • HTN, type 2 DM, obstructive sleep apnea, and osteoarthritis • Obese patients pose unique surgical risks that warrant attention in the perioperative period

7. Perioperative Risk Reduction • Hypertension and diabetes require special attention to achieve adequate control and management of medications perioperatively • Screen for evidence of cardiovascular disease: • Resting ECG • Exercise tolerance assessment • Orthopnea and fluid retention may be only findings See Notes for references.

8. Screening for OSA • The STOP questionnaire is a simple tool: • Snoring • Tiredness during the daytime • Observed apneas • High blood Pressure • BANG: BMI, Age, Neck circumference, Male Gender • Polysomnography is the gold standard test • Assume morbidly obese patients have OSA See Notes for references.

9. Screening for OSA: Prevention • Untreated chronic OSA increases operative risk • Recommend 4-6 weeks of CPAP therapy prior to planned surgery • CPAP reduces systemic and pulmonary HTN See Notes for references.

10. Case: Surgical Safety (3) The patient underwent a preoperative evaluation and, after a discussion about risks and benefits, he consented for a total knee replacement. The plan was to use general anesthesia supplemented by use of an epidural catheter for post-operative pain control.

11. Case: Surgical Safety (4) In the operating suite, the patient was placed in a supine position for induction of anesthesia. The patient soon experienced hemodynamic instability and hypoxia, and, despite many efforts, providers were unable to establish a functioning airway. The patient soon became pulseless, a code was called, and the patient expired after failed resuscitative attempts.

12. Anesthesia & the Airway • Regional anesthesia confers several advantages in the obese patient, including minimal need for airway manipulation • Epidural catheters can provide excellent postoperative pain control to minimize opioid use, which can leave obese patients less prone to pulmonary complications • Large neck circumference (> 40 cm) and Mallampati score of III-IV are best predictors of potential airway difficulties See Notes for references.

13. Mallampati Scoring System • Used to predict ease of intubation • Class I: full visibility of tonsils, uvula, and soft palate • Class II: visibility of hard and soft palate, upper portion of tonsils and uvula • Class III: soft and hard palate and base of uvula are visible • Class IV: only hard palate visible Illustration © Chris Gralapp

14. Tragic Outcome • Key error was inducing general anesthesia with patient in supine position • Supine position leads to poor chest wall compliance, greater perfusion mismatch, and a sudden shift of blood to an already hyperactive hypoxic heart • Obesity supine death syndrome has been described See Notes for references.

15. Prevention Strategies • Proper positioning is essential • Head up with bed in reverse Trendelenburg position • Use of depolarizing relaxant succinylcholine is preferred over non-depolarizing agents • Consider use of a surgical safety checklist and/or algorithms for obese patients undergoing surgery • Continued education for trainees and current providers on issues in this patient population See Notes for references.

16. Proper Positioning Illustration © Chris Gralapp

17. Take-Home Points (1) • Since morbid obesity is associated with so many medical comorbidities, preoperative evaluation is essential to recognize these medical and physiologic changes • The STOP-BANG questionnaire helps identify the presence of OSA; all morbidly obese patients should be treated as if they have OSA. • Minimize or avoid sedatives and opioids during the entire perioperative period.

18. Take-Home Points (2) • A sedated morbidly obese patient should never lie supine. For induction of general anesthesia, always ensure proper positioning to maximize oxygen reserves. • Whenever practical, chose a regional anesthetic and avoid general anesthesia and tracheal intubation.