Adult Obesity And Obstructive Sleep Apnea

Educational Objectives

The goal of this program is to improve perioperative care of obese patients and patients with obstructive sleep apnea (OSA). After hearing and assimilating this program, the clinician will be better able to:

1. Adjust medication doses to account for obesity.

2. Perform preoperative evaluation of obese patients.

3. Safely extubate and monitor obese patients postoperatively.

4. Recognize the prevalence and physiologic consequences of OSA.

5. Minimize perioperative risks for patients with diagnosed or suspected OSA.

Summary

Obesity

Background: body mass index (BMI) commonly used for assessment of obesity; not optimal, but easy to calculate; Kartheuser et al (2013) found waist/hip ratio correlated with increased odds of surgical complications for patients undergoing colorectal surgery, but BMI did not

Prevalence of obesity: prevalence of obesity, severe obesity, and morbid obesity increasing across all age groups in United States; percentage of obese people in population projected to reach 50% by 2030; prevalence of comorbidities associated with obesity (eg, diabetes mellitus [DM], coronary artery disease [CAD], stroke, hypertension, arthritis) projected to increase between 2- and 4-fold; ≈33% of patient population in United States overweight (BMI between 25 and 29); ≈39% obese (BMI between 30 and 40); ≈7% morbidly obese (BMI >40); ≈31% of children and adolescents either overweight or obese; Geserick et al (2018) found size of child between ages of 2 and 6 yr predictive for obesity as adult

Cardiovascular factors: obese children at higher risk for hypertension, asthma, sleep apnea, gastroesophageal reflux, and DM compared with nonobese children; overweight and obese adolescents more likely to develop risk factors for cardiovascular disease; American Heart Association (Jensen et al, 2014) stated overweight and obese patients are at increased risk for changes on electrocardiography, left and right atrial dilation, left ventricular dysfunction, and cardiac failure; Al Otair et al (2018) found two-thirds of patients with obesity hypoventilation syndrome had left ventricular diastolic dysfunction

Pulmonary abnormalities: work of breathing increases; functional residual capacity smaller than closing capacity, so obese patients have atelectasis while awake (particularly when supine); data suggest that findings of pulmonary function testing drop by 30% for ≥1 day after upper abdominal or laparoscopic procedure

Additional abnormalities: insulin resistance increases with increasing obesity; obese patients at increased risk for prothrombotic state, venous thromboembolism, and deep venous thrombosis; pneumatic compression devices and compression stockings often fit poorly; data from 2012 — obesity-related diseases estimated to be number one type of liver diseases; nonalcoholic fatty liver disease and nonalcoholic steatohepatitis estimated to affect ≈50% of adult population and ≥10% of adolescent population in United States

Drug dosing: use ideal body weight (IBW) or IBW plus correction factor for induction; cases have been reported of patient recall of staff comments because propofol used for induction wore off before volatile anesthetics took full effect

Trauma: obese drivers ≤78% more likely to die or experience severe injuries in motor vehicle accidents than normal-weight individuals; safety mechanisms in automobiles are designed to protect 170-lb crash test dummy

Preoperative evaluation: evaluation must occur sufficiently early to allow time for optimization of comorbidities; ask specifically about supplements for weight loss in addition to medications; “ECA stack” type of supplement most common; contain ephedrine 25 to 30 mg, caffeine 200 to 300 mg, and aspirin 200 to 300 mg; taken ≤3 times per day; speaker reports case of patient taking supplements experiencing profound hypotension refractory to ephedrine during induction with propofol; important to discuss anesthetic plan with patient (patient must be informed if, eg, planning awake intubation) and to ask patient about expectations

Medications: minimize use of opioids; consider fentanyl instead of morphine for patient-controlled analgesia (PCA); consider PCA with demand only (no basal rate); consider multimodal analgesia; at Baylor University Medical Center in Dallas, changing from narcotic-based balanced technique to approach using dexmedetomidine for bariatric surgeries significantly changed postoperative management; literature supports use of low-dose dexmedetomidine and ketamine for obese patients

Postoperative care: policy at Mount Sinai Medical Center requires presence of 2 individuals trained in anesthesia in room during extubation of morbidly obese patient (defined as BMI >40), pressure support ventilation or reverse Trendelenburg position, documentation of recovery from neuromuscular blockade, sitting up, continuous positive airway pressure (CPAP) or bilevel positive airway pressure in operating room (OR), and observation for 5 min in OR after extubation before transfer to postanesthesia care unit (PACU); monitored setting for 4 to 6 hr in PACU required; patients receiving PCA require monitoring of oxygen saturation, capnography, and respiratory rate for 24 hr

Positioning: literature suggests obese patients susceptible to stretch injuries of brachial plexus, ulnar neuropathies, and injuries to lateral femoral cutaneous nerve (particularly in lithotomy position)

Bariatric surgery: studies have shown bariatric surgery associated with significantly greater weight loss and improvement of sleep apnea compared with diet and exercise; indications for bariatric surgery expanded from morbid obesity with failure of conservative therapy to include type 2 DM, cardiovascular disease, metabolic problems, and other comorbidities; insurance companies increasingly paying for bariatric surgery for expanded list of indications because cost of surgery considerably less than lifetime cost of managing comorbidities

Risk for adverse outcomes of bariatric surgery: published perioperative mortality between 0.1% and 0.2%; speaker reports case of anesthesiologist sued after placement of bougie caused tear in distal esophagus requiring open thoracotomy and repair; Signorini et al (2018) discussed iatrogenic injuries to esophagus during placement of bougie; documented 59 lawsuits in United States involving gastroenterologists, general surgeons, and/or anesthetists; median settlement $650,000; median jury award $1.2 million; authors concluded that informed consent should always include possibility of esophageal perforation

New device: implantable device (Maestro Rechargeable System, approved by Food and Drug Administration [FDA] in 2015) incorporates generator and wires; wires placed on vagus nerve; stimulation of vagus thought to send signals of satiety to brain and decrease food consumption; placed under general anesthetic

New combination drug: combination of naltrexone and bupropion (Contrave) approved for weight loss by FDA in 2014; maintenance dose 2 tablets orally twice per day; each tablet contains 8 mg naltrexone (32 mg daily); recommended to hold for 10 days before surgery to prevent interference with perioperative opioids

Deep neuromuscular blockade: easier to obtain pneumoperitoneum and visualization in lean patients; more pressure required for obese patients; surgeons frequently request complete paralysis (no twitches) for obese patients; surgical literature suggests deep neuromuscular blockade produces better operative conditions during laparoscopy and leads to better outcomes; reversal — time required for reversal of deep blockade presents issue; speaker recommends maintaining availability of sugammadex on formulary if surgeons demand deep blockade; may have institution’s Chief of Surgery demand availability of sugammadex (especially if cost becomes issue)

Obstructive Sleep Apnea (OSA)

Prevalence and complications: National Sleep Foundation estimates 18 to 20 million patients in United States at increased risk during surgery because of unknown OSA; OSA as common as DM and asthma; about half as common as CAD; patients generally know if they have CAD, asthma, or DM; many patients with OSA do not know they have it; complications related to OSA include postoperative hypoxia, respiratory complications, neurologic complications, cardiac complications, extended stays, overnight admissions for planned outpatient procedures, and unplanned admission to intensive care unit (ICU) for respiratory complications; Society of Anesthesia and Sleep Medicine published guidelines for preoperative screening, intraoperative management, and postoperative management

Definition of OSA: intermittent partial or complete obstruction of upper airway during sleep; specific definition full obstruction with no movement of air for ≥10 sec despite attempt of patient to breathe; definition of hypopnea reduction of airflow by ≥50% for >10 sec; severe sleep apnea defined as ≥40 episodes/hr during sleep study

Systemic effects: OSA results in oxygen desaturation, hypercarbia, and cardiovascular dysfunction; physiology of OSA equal to that of ischemia reperfusion; nightly, consistent high-frequency intermittent hypoxia and hypercarbia thought to cause ischemia reperfusion physiology, tissue oxidative stress, systemic and vascular inflammation, and endothelial cell dysfunction; interleukin 6 and other biomarkers under investigation for determining severity of OSA; cardiac literature states OSA associated with congestive heart failure, right and left ventricular hypertrophy (likely in 75% of patients; patients often unaware), pulmonary hypertension leading to stretching of right heart and rhythm disturbances, secondary heart block, atrial fibrillation, and silent ST segment changes; likely that many patients have OSA with associated comorbidities but remain unaware

Outcomes: Buchner et al (2007) found treatment of OSA reduced risk of fatal and nonfatal cardiovascular events by 64% (included patients with mild to moderate OSA); OSA independent risk factor for stroke; study found 70% to 90% of patients with first-time stroke and without other etiology (eg, atrial fibrillation) had OSA; OSA independently associated with anterior ischemic optic neuropathy; also associated with higher incidence of difficult intubation, higher incidence of postoperative complications, increased admissions to ICU, and longer duration of hospital stay; average lifespan of patient with untreated sleep apnea 20 yr shorter than for general population

Pediatric patients: in survey, one-third of preadolescent and 40% of adolescent patients reported problems with sleeping, including OSA; in survey of pediatricians, only 13% correctly answered questions related to sleep apnea

Attention-deficit hyperactivity disorder (ADHD) vs OSA: update of OSA guidelines states daytime somnolence in adults described as ability to fall asleep during quiet conversation, lunch without alcohol, or watching television; described in children as daytime sleepiness, easily distracted, excessive aggressiveness, and difficulty with concentration; many children displaying such behavior diagnosed with ADHD and treated with methylphenidate (Ritalin) or dextroamphetamine-amphetamine (Adderall); speaker suggests child diagnosed with ADHD might have undiagnosed OSA; suggests consideration for monitoring children with ADHD postoperatively as if diagnosed with OSA

STOP-Bang Questionnaire: tool for initial screening for OSA; patient positive for ≥2 out of first 4 elements or for ≥3 of 8 elements potentially at increased risk for OSA; consider further workup; patient with score <2 reliably excluded from risk for moderate or severe OSA with 95% confidence interval; patients with ≥6 positive responses have 90% likelihood of OSA; patients with scores between 3 and 5 less clear; logistics and costs of sleep study may present barriers; devices for monitoring patients’ oxygen saturation at home are available; speaker suggests having patient check saturation at home overnight if sleep study not feasible

Risk management: inform patient and surgeon of potential implications of sleep apnea on patient’s course; not sufficient to simply ensure patient wears CPAP device postoperatively; patient with CPAP possibly at increased risk for negative pressure pulmonary edema or for vomiting and aspiration because of tight-fitting mask; potential for patient who appears comfortable to be hypercarbic; supplemental oxygen might maintain oxygen saturations while disguising hypoventilation; speaker raises possibility of having increased nursing patient acuity ratios for OSA patients in PACU for certain period of time

Recommendations from American Society of Anesthesiologists: avoid continuous infusions and exercise extreme caution if using PCA; provide supplemental oxygen and monitor with pulse oximetry until patient returns to baseline; hospitalized patients at increased risk for sleep apnea should have continuous monitoring with pulse oximetry after discharge from PACU; continuous monitoring defined as ICU, step-down telemetry unit, or trained dedicated person remaining in room to watch monitor; intermittent pulse oximetry or continuous oximetry without remote monitoring does not provide same level of safety

Discharge: no evidence-based guidelines to guarantee safe discharge; necessary to use experience and judgment; inappropriately early discharge potentially life threatening; default decision should be monitored hospital bed for borderline cases

Monitoring: prototypical malpractice lawsuit for sleep apnea (70% of cases) involves finding patient dead in bed on floor unit; first 24 hr most life-threatening and critical; patients with sleep apnea have increased sensitivity to opioids and require more cautious approach, including monitoring

Respiratory depression: chronic hypoxia and hypercarbia in patients with sleep apnea alter central respiratory drive, leading to increased sensitivity to respiratory depressive effects of narcotics; recommended to reduce doses of narcotics by 50%; some facilities institute policies for standing orders allowing floor nurses to administer naloxone for respiratory depression; some facilities ensure availability of naloxone in multiple locations

Role of surgeons: identify patients at risk for OSA preoperatively; minimize use of sedatives; reduce doses of narcotics; limit PCA to demand doses and avoid basal rates

Perioperative outcomes: patients with sleep apnea have 5 times higher odds of myocardial infarction and 5 times higher odds of pulmonary complications; they also require increased utilization of resourcesAcknowledgments

Readings

Al Otair HA et al: Left ventricular diastolic dysfunction in patients with obesity hypoventilation syndrome. J Thorac Dis 2018 Oct;10(10):5747-54; Buchner NJ et al: Continuous positive airway pressure treatment of mild to moderate obstructive sleep apnea reduces cardiovascular risk. Am J Respir Crit Care Med 2007 Dec 15;176(12):1274-80; Chung F et al: Postoperative changes in sleep-disordered breathing and sleep architecture in patients with obstructive sleep apnea. Anesthesiology 2014 Feb;120(2):287-98; Chung F et al: Society of Anesthesia and Sleep Medicine guidelines on preoperative screening and assessment of adult patients with obstructive sleep apnea. Anesth Analg 2016 Aug;123(2):452-73; Davis S et al: Perioperative mortality following bariatric surgery in Australia. Obes Surg 2018 May;28(5):1329-34; Geserick M et al: Acceleration of BMI in early childhood and risk of sustained obesity. N Engl J Med 2018 Oct 4;379(14):1303-12; Jensen MD et al: 2013 AHA/ACC/TOS guideline for the management of overweight and obesity in adults: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and The Obesity Society. Circulation 2014 Jun 24;129(25 Suppl 2):S102-38; Kartheuser AH et al: Waist circumference and waist/hip ratio are better predictive risk factors for mortality and morbidity after colorectal surgery than body mass index and body surface area. Ann Surg 2013 Nov;258(5):722-30; Memtsoudis SG et al: Society of Anesthesia and Sleep Medicine guideline on intraoperative management of adult patients with obstructive sleep apnea. Anesth Analg 2018 Oct;127(4):967-87; Nadeem R et al: Serum inflammatory markers in obstructive sleep apnea: a meta-analysis. J Clin Sleep Med 2013 Oct 15;9(10):1003-12; Signorini FJ et al: Iatrogenic injury of the intrathoracic oesophagus with bougie during sleeve gastrectomy. J Minim Access Surg 2018 Jan-Mar;14(1):79-82.

Disclosures

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

Acknowledgements

Dr. Murphy was recorded at the American Osteopathic College of Anesthesiologists’ 46th Annual Midyear Seminar, held March 15-17, 2019, in Chicago, IL, and presented by the American Osteopathic College of Anesthesiologists. For information about upcoming CME opportunities from the American Osteopathic College of Anesthesiologists, please visit aocaonline.org. The Audio Digest Foundation thanks Dr. Murphy and the American Osteopathic College of Anesthesiologists 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:

AN613101

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.

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