Obstructive sleep apnea syndrome (OSAS) is a disorder in which patients periodically stop breathing during sleep. Research suggests that OSAS occurs in approximately 5% to 9% of the general population, with obese men affected most often. Research also suggests that OSAS is common among patients undergoing surgery. Studies have observed an increased risk of postoperative complications in patients with OSAS when compared with control subjects. Others have demonstrated that postoperative complication rates increase as the number of episodes of overnight desaturation increase. “The related cardiorespiratory consequences may be exacerbated after surgical procedures because anesthetic agents and pain relievers decrease muscle tone in the upper airways,” explains Tajender S. Vasu, MD. “This can diminish control of breathing. As a result, it’s important to identify surgical patients who are at high risk for OSAS.”
Nocturnal polysomnography is the standard for diagnosing OSAS. Home sleep testing has also gained increasing acceptance and offers advantages to nocturnal polysomnography because of convenience and cost. “Unfortunately, neither of these diagnostics is used extensively in preoperative assessment settings,” says Dr. Vasu. “Therefore, most preoperative patients with OSAS have not had their conditions diagnosed. This raises the potential for a negative effect on postoperative outcome.”
The STOP-BANG Questionnaire
Recently, the STOP-BANG questionnaire was validated as a screening modality for OSAS in the preoperative setting. The questionnaire—which is a mnemonic that stands for snoring, tiredness during daytime, observed apnea, high blood pressure, BMI, age, neck circumference, and gender—is a concise, self-administered, and easy-to-use questionnaire that consists of eight “yes or no” questions (Figure). A study published in the October 2010Archives of Otolaryngology–Head & Neck Surgery evaluated the clinical usefulness of the STOP-BANG questionnaire in the surgical setting. Dr. Vasu and colleagues studied 135 patients undergoing elective surgery in May 2008, all of whom completed the STOP-BANG questionnaire before elective procedures.
Of the patients involved in the study, 41.5% (56 people) had a high STOP-BANG risk score, indicating that they had a high risk for OSAS. Patients with higher scores on STOP-BANG had increased rates of postoperative pulmonary or cardiac complications (19.6% vs 1.3%) and longer hospital stays (3.6 days vs 2.1 days) when compared with patients who had lower scores. Several factors also conferred higher risks of OSAS, including advanced age, obesity, those with higher anesthesia risks, and those considered at high risk for OSAS (Table).
“It’s important to identify surgical patients who are at high risk for OSAS.”
“Our study demonstrated that the STOP-BANG questionnaire is an effective, convenient, and useful screening tool that appears to reliably identify patients who are at increased risk for postoperative complications resulting from OSAS,” says Dr. Vasu. “The approximate 10-fold risk of postoperative complications we observed in patients undergoing elective surgery is substantial, further validating the notion that OSAS is highly prevalent among surgical patients.”
Dr. Vasu and colleagues note that the high rate of postoperative complications that were observed in patients with OSAS may be due to a variety of reasons. For example, central nervous system suppression can result from anesthesia, sedation, and analgesia, and may lead to sleep-disordered breathing or asphyxia-related complications. In addition, REM sleep diminishes on the first postoperative night. This typically is followed by a rebounding of REM on subsequent nights. The result of this phenomenon is that REM-associated hypoxemic episodes may increase significantly on the second and third postoperative nights. In turn, this can lead to an increased risk of complications.
Another important finding of the Archives of Otolaryngology–Head & Neck Surgery study is that the researchers found the STOP-BANG questionnaire to have a sensitivity of 91.7% and a specificity of 63.4% in identifying patients at high risk for postoperative complications utilizing a cutoff score of 3 or higher. “Interestingly, this cutoff point also had a high negative predictive value,” says Dr. Vasu. “Therefore, it appears that this questionnaire is a good tool to identify complications during preoperative evaluation. We hope that other studies will provide external validation of our study results.”
Readings & Resources (click to view)
Vasu TS, Doghramji K, Cavallazzi R, et al. Obstructive sleep apnea syndrome and postoperative complications: clinical use of the STOP-BANG questionnaire. Arch Otolaryngol Head Neck Surg. 2010;136:1020-1024. Available at: http://archotol.ama-assn.org/cgi/content/full/136/10/1020.
Chung F, Elsaid H. Screening for obstructive sleep apnea before surgery: why is it important? Curr Opin Anaesthesiol. 2009;22:405-411.
Paje DT, Kremer MJ. The perioperative implications of obstructive sleep apnea. Orthop Nurs. 2006;25:291-299.
Hwang D, Shakir N, Limann B; et al. Association of sleep-disordered breathing with postoperative complications. Chest. 2008;133:1128-1134.