Hisham Elsaid

Screening for obstructive sleep apnea before surgery: why is it important?

Purpose of review The purpose of this article is to review the screening tools available in the preoperative clinic for patients at risk of obstructive sleep apnea. Recent findings Obstructive sleep apnea (OSA) is the most prevalent sleep disorder. An estimated 82% of men and 92% of women with moderate-to-severe sleep apnea have not been diagnosed. Patients with undiagnosed OSA may have increased perioperative complications. The perioperative risk of patients with OSA may be reduced by appropriate screening to detect undiagnosed OSA in patients. The snoring (S), tiredness (T) during daytime, observed apnea (O), and high blood pressure (P) (STOP) questionnaire is a concise and easy-to-use screening tool to identify patients with a high risk of OSA. It has been validated in surgical patients at preoperative clinics as a screening tool. Incorporating BMI, age, neck size and gender into the STOP questionnaire (STOP-Bang), will further increase the sensitivity and negative predictive value (NPV), especially for patients with moderate-to-severe OSA. Summary The STOP questionnaire is short and can be easily incorporated into routine screening of general or surgical patients.

Oxygen desaturation index from nocturnal oximetry: a sensitive and specific tool to detect sleep-disordered breathing in surgical patients.

INTRODUCTION: It is impractical to perform polysomnography (PSG) in all surgical patients suspected of having sleep disordered breathing (SDB). We investigated the role of nocturnal oximetry in diagnosing SDB in surgical patients. METHOD: All patients 18 years and older who visited the preoperative clinics for scheduled inpatient surgery were approached for study participation. Patients expected to have abnormal electroencephalographic findings were excluded. All patients underwent an overnight PSG at home with a portable device and a pulse oximeter. The PSG recordings were scored by a certified sleep technologist. The oximetry recordings were processed electronically. RESULT: Four hundred seventy-five patients completed the study: 217 males and 258 females, aged 60 ± 11 years, and body mass index 31 ± 7 kg/m2. The apnea-hypopnea index (AHI), the average number of episodes of apnea and hypopnea per hour of sleep, was 9.1 (2.8 to 21.4) [median (interquartile range)] and 64% patients had AHI >5. There was a significant correlation between oxygen desaturation index (ODI, hourly average number of desaturation episodes) and cumulative time percentage with SpO2 <90% (CT90) from nocturnal oximetry, with the parameters measuring sleep breathing disorders from PSG. Compared to CT90, ODI had a stronger correlation and was a better predictor for AHI. The area under receiver operator characteristics curve for ODI to predict AHI >5, AHI >15, and AHI >30 was 0.908 (CI: 0.880 to 0.936), 0.931 (CI: 0.090 to 0.952), and 0.958 (CI: 0.937 to 0.979), respectively. The cutoff value based on the maximal accuracy for ODI to predict AHI >5, AHI >15, and AHI >30 was ODI >5, ODI >15, and ODI >30. The accuracy was 86% (CI: 83%–88%), 86% (CI: 83%–89%), and 94% (CI: 92%–96%), respectively. The ODI >10 demonstrated a sensitivity of 93% and a specificity of 75% to detect moderate and severe SDB. CONCLUSIONS: ODI from a high-resolution nocturnal oximeter is a sensitive and specific tool to detect undiagnosed SDB in surgical patients.

Perioperative auto-titrated continuous positive airway pressure treatment in surgical patients with obstructive sleep apnea: a randomized controlled trial.

Background:Obstructive sleep apnea (OSA) may worsen postoperatively. The objective of this randomized open-label trial is to determine whether perioperative auto-titrated continuous positive airway pressure (APAP) treatment decreases postoperative apnea hypopnea index (AHI) and improves oxygenation in patients with moderate and severe OSA. Methods:The consented patients with AHI of more than 15 events/h on preoperative polysomnography were randomized into the APAP or control group (receiving routine care). The APAP patients received APAP for 2 or 3 preoperative, and 5 postoperative nights. All patients were monitored with oximetry for 7 to 8 nights (N) and underwent polysomnography on postoperative N3. The primary outcome was AHI on the postoperative N3. Results:One hundred seventy-seven OSA patients undergoing orthopedic and other surgeries were enrolled (APAP: 87 and control: 90). There was no difference between the two groups in baseline data. One hundred six patients (APAP: 40 and control: 66) did polysomnography on postoperative N3, and 100 patients (APAP: 39 and control: 61) completed the study. The compliance rate of APAP was 45%. The APAP usage was 2.4–4.6 h/night. In the APAP group, AHI decreased from preoperative baseline: 30.1 (22.1, 42.5) events/h (median [25th, 75th percentile]) to 3.0 (1.0, 12.5) events/h on postoperative N3 (P < 0.001), whereas, in the control group, AHI increased from 30.4 (23.2, 41.9) events/h to 31.9 (13.5, 50.2) events/h, P = 0.302. No significant change occurred in the central apnea index. Conclusions:The trial showed the feasibility of perioperative APAP for OSA patients. Perioperative APAP treatment significantly reduced postoperative AHI and improved oxygen saturation in the patients with moderate and severe OSA.

Factors associated with postoperative exacerbation of sleep-disordered breathing.

Introduction:The knowledge on the mechanism of the postoperative exacerbation of sleep-disordered breathing may direct the perioperative management of patients with obstructive sleep apnea. The objective of this study is to investigate the factors associated with postoperative severity of sleep-disordered breathing. Methods:After obtaining approvals from Institutional Review Boards, consenting patients underwent portable polysomnography preoperatively, and on postoperative nights 1 and 3 in hospital or at home. The primary outcomes were polysomnography parameters measuring the sleep-disordered breathing. They were treated as repeated measurement variables and analyzed for associated factors by mixed models. Results:Three hundred seventy-six patients, 168 men and 208 women, completed polysomnography on preoperative and postoperative night 1. Age was 59 ± 12 yr (mean ± SD). Preoperative apnea–hypopnea index (AHI) was 12 (4, 26) (median [25th, 75th percentile]) events per hour. Thirty-five patients had minor surgeries, 292 intermediate surgeries, and 49 major surgeries, with 210 general anesthesia and 166 regional anesthesia. The 72-h opioid dose was 55 (14, 85) mg intravenous morphine-equivalent dose. Preoperative AHI, age, and 72-h opioid dose were associated with postoperative AHI. Preoperative central apnea index, male sex, and general anesthesia were associated with postoperative central apnea index. Slow wave sleep percentage was inversely associated with postoperative AHI and central apnea index. Conclusions:Patients with a higher preoperative AHI were predicted to have a higher postoperative AHI. Preoperative AHI, age, and 72-h opioid dose were positively associated with postoperative AHI. Preoperative central apnea, male sex, and general anesthesia were associated with postoperative central apnea index.

Screening adults for obstructive sleep apnea

Obstructive sleep apnea (OSA) is the most prevalent breathing disturbance during sleep [1], affecting 2% to 6% of the general population, depending on age, sex, and the defi nition of criteria [2]. An estimated 82% of men and 92% of women with moderate to severe OSA have not been diagnosed [3]. Sleep apnea events are defi ned as a complete cessation of breathing (apnea) or a marked reduction in airfl ow (hypopnea) during sleep, and are considered clinically relevant if they last more than 10 seconds. The episodes of apneas and hypopneas may persist for 30 to 60 seconds in some individuals. OSA is characterized by repetitive obstruction of the upper airway, often resulting in oxygen desaturation and arousals from sleep. The classic daytime manifestation is excessive sleepiness, and other symptoms such as non-refreshing sleep, poor concentration, and fatigue are commonly reported [4]. OSA is a serious condition that diminishes the quality of life [5] and is also associated with many common comorbidities. Studies have documented an increased incidence of coronary artery disease, hypertension, congestive heart failure, cerebrovascular accidents, and gastroesophageal refl ux disease in OSA patients [6,7]. It is estimated that the average life span of an untreated OSA patient is 58 years, much shorter than the average life spans of 78 years for men and 83 years for women [8]. The signs and symptoms of OSA are shown in Table 1.