97

VI

Chapter 15

Obstructive Sleep Apnea

Molly Blackley Jackson

Obstructive sleep apnea (OSA) is a major risk factor for intra- and postoperative complications, including post-extubation hypoxemia, hypercarbia, unplanned reintubation, pneumonia, all-cause respira-tory failure, cardiac complications (including arrhythmia and myocar-dial injury), unplanned ICU transfer, longer length-of-stay, and even sudden death [ 1– 3 ] . The use of sedatives/analgesics and postoperative sleep deprivation likely play a major role in these adverse events [ 4 ] .

Sleep-disordered breathing is common, affecting 20% of adults, with up to 7% with moderate or severe OSA, and studies have sug-gested that up to 80% of patients with OSA in the general population are undiagnosed [ 5 ] . These numbers are likely higher among surgical patients, especially candidates for bariatric surgery [ 6 ] . In patients with OSA, pre-op CPAP compliance has been shown to reduce postop-erative complications [ 7 ] .

PREOPERATIVE EVALUATION HISTORY/EXAM

Risk factors: Advanced age, male, hypertension, obesity, alco- ■

hol intake, menopause. Symptoms: Daytime somnolence or napping, non-restorative ■

sleep, witnessed snoring /apnea, awakening from sleep (rest-lessness, choking), morning headaches. Use a systematic screening tool, such as STOP-Bang. See ■

Table 15.1 [ 8 ] .

Workup : Consider if risk is high and surgery is not urgent. Gold standard: Overnight polysomnogram (PSG). ■

C.J. Wong and N.P. Hamlin (eds.), The Perioperative Medicine Consult Handbook, DOI 10.1007/978-1-4614-3220-3_15, © Springer Science+Business Media New York 2013

98 THE PERIOPERATIVE MEDICINE CONSULT HANDBOOK

Apnea–hypopnea index (AHI) = number of apneas + hypopneas/ ■

number of hours of sleep: 5–15 (mild), 15–30 (moderate), >30 (severe). CPAP machine covered by Medicare and Medicaid if AHI >15, ■

or AHI >5 with severe symptoms or comorbidities (HTN, CAD, CVA, etc.) [ 4 ] .

PATIENTS WITH KNOWN OSA Document CPAP or BIPAP settings, type of mask (nasal vs. full ■

face), amount of bleed-in oxygen (if any), and actual patient compliance. If patients have an ill- fi tting mask, refer back to their sleep ■

clinic for mask re fi tting. Remind patients to bring mask and machine (labeled with ■

name) to the hospital. Assess for signs and symptoms of pulmonary hypertension (see ■

Chap. 16 ) and right heart failure; consider echocardiogram in selected cases (see “Discussion”). Consider obtaining a preoperative room air ABG, if mild ■

hypoxia or evidence for daytime hypercarbia (e.g., elevated serum bicarbonate). Alert anesthesia and operative team to the presence of known ■

or suspected obstructive sleep apnea (OSA) before surgery.

TABLE 15.1 STOP-BANG SCREENING TOOL FOR OBSTRUCTIVE SLEEP APNEA [ 8 ]

S = Snoring. Do you snore loudly ( louder than talking or loud enough to be heard through closed doors )?

T = Tiredness. Do you often feel tired, fatigued, or sleepy during daytime? O = Observed apnea. Has anyone observed you stop breathing during your

sleep? P = Pressure. Do you have or are you being treated for high BP? B = BMI > 35 kg/m 2 A = Age > 50 years N = Neck circumference >40 cm G = Male gender

High risk of OSA: ³ 3 of the above Low risk of OSA: <3 of the above

Using 3 as a cutoff, this tool has a 93% sensitivity and 47% speci fi city for OSA

Reprinted with permission from [ 8 ]

99CHAPTER 15: OBSTRUCTIVE SLEEP APNEA

VI

POSTOPERATIVE MANAGEMENT Extubate directly to CPAP/BiPAP at home settings, and con- ■

tinue when sleeping (including naps). Close respiratory monitoring, especially with sedating medica- ■

tions (e.g., opiates). Consider ICU care, or continuous pulse oximetry monitoring if ■

on fl oor care, depending on the extent of surgery, severity of OSA, and compliance with CPAP. Semi-upright (30–45°) or lateral (side-lying) positioning, if ■

possible. If cannot tolerate CPAP or cannot use CPAP due to the surgical ■

site, initiate supplemental O 2 while sleeping (exercise caution in patients with COPD). Minimize opiate medications when possible (considering ■

scheduled acetaminophen or NSAIDS to augment pain control in appropriate candidates). If surgery is urgent and the risk for OSA is high but there is no ■

time for testing, consider intensive respiratory observation (ICU or similar) for the fi rst 24 h; if any evidence of hypercarbia or hypoxemia, consider ABG and/or a trial of noninvasive posi-tive pressure ventilation (CPAP or BiPAP).

AMBULATORY SURGERY Monitoring in patients with OSA after ambulatory surgery is contro-versial. ASA practice guidelines (based on expert opinion) recommend observing patients for an additional 3 h before discharging home, and if there is any episode of airway obstruction or apnea, monitoring should continue for an additional 7 h [ 9 ] . These recommendations hold even for patients who undergo only regional anesthetic block.

DISCUSSION We recommend very close attention perioperatively to patients with OSA. The appropriate setting for adequate respiratory monitoring is institution and surgery dependent. It deserves mention that most screening tools for OSA are quite sensitive, but not terribly speci fi c, and are not designed speci fi cally for “preoperative” screening. Thus, these tools recommend formal testing for OSA in a higher percentage of patients than may be necessary prior to surgery. Using sound

100 THE PERIOPERATIVE MEDICINE CONSULT HANDBOOK

clinical judgment in combination with these tools is a reasonable approach.

At least mild pulmonary hypertension (PAH) may be present in up to half of the patients with OSA, although OSA is an unusual cause of moderate or severe PAH. Many patients with OSA have dyspnea on exertion due to obesity and deconditioning, and/or edema due to venous stasis, without having right heart failure or PAH. Neck veins in these patients are dif fi cult to assess. It is unknown to what degree screening for PAH by transthoracic echocardiogram (TTE) changes management or affects outcomes. The American College of Chest Physicians does not recommend routine evaluation for PAH in all-comers with OSA, but consideration of TTE is reasonable in newly diagnosed patients who are set to undergo high-risk surgical proce-dures and/or are likely to receive high doses of post-op opioids [ 10 ] . TTE may also be considered in patients with OSA who have poor exercise tolerance and/or who are anticipated to undergo laparoscopic surgery.

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and obstructive sleep apnea: implications for treatment. Chest. 2010;137(3):711–9. 3. Memtsoudis S, Liu SS, Ma Y, et al. Perioperative pulmonary outcomes in patients with sleep

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