Literature Updates from December 2018

Pulmonary rehabilitation and oropharyngeal exercises as an adjunct therapy in obstructive sleep apnea: a randomized controlled trial

This study was a two-arm, parallel, randomized, controlled and open-label trial of 40 patients with moderate to severe obstructive sleep apnea. The patients were randomized to continuous positive airway pressure (CPAP) and CPAP + pulmonary rehabilitation (PR). The PR group underwent six weeks of 60-min twice-weekly individual PR programs. It was found that CPAP with a rehabilitation program improved functional ventilatory parameters and decreased BMI in patients with OSA. Hence, Treatment with CPAP combined with the PR program improved OSA patients to a greater extent than only CPAP and can be a useful part of comprehensive therapy in OSA.

Is obstructive sleep apnea associated with difficult airway? Evidence from a systematic review and meta-analysis of prospective and retrospective cohort studies.

For several years, OSA was known to be a risk factor of difficult airway. There are two interests in this meta-analysis. Firstly, the authors found that OSA had a three to four-fold higher risk of difficult intubation or mask ventilation or both, when compared to non-sleep apnea patients. Secondly, the authors found that there was no significant difference in the supraglottic airway failure rates in the sleep apnea vs non-sleep apnea patients. This is a very interesting information for the management of the upper airway in the operating room.

Sleep disturbances and sleep disorders in adults living with chronic pain: a meta-analysis

Chronic pain (CP) is widespread and commonly associated with sleep disturbances. However, research has often used poor quality measures of sleep which is often focused on specific pain conditions, thereby limiting its reliability and applicability to the wider CP population. This is a meta-analysis of the studies that used objective polysomnographic measures of sleep or examined diagnosed sleep disorders in people with CP. The results found that the pooled prevalence of sleep disorders in CP was 44%, with insomnia (72%), restless legs syndrome (32%) and obstructive sleep apnea (32%) being the most common diagnoses. Also, objective polysomnographic measures indicate that individuals with CP experience significant sleep disturbances, particularly with respect to sleep initiation and maintenance. Hence, it is imperative that sleep disturbances and disorders be assessed and treated in conjunction with the CP.

Improvement in Nocturnal Hypoxemia in Obese Patients with Obstructive Sleep Apnea after Bariatric Surgery: a Meta-Analysis.

For a couple of years, there are increasing evidences that nocturnal hypoxemia may play an important role in the pathophysiology of OSA. In this meta-analysis, the authors found that bariatric surgery is effective at improving nocturnal hypoxemia in obese patients with OSA. The reduction in body weight may be the predominant factor. However, their findings must be confirmed by other studies.

Can STOP-Bang and Pulse Oximetry Detect and Exclude Obstructive Sleep Apnea?

In this study, conducted in Sweden, the authors found that a STOP-Bang score < 2 almost excludes moderate and severe OSA, whereas nearly all the patients with a STOP-Bang score ≥ 6 have OSA. For patients with an intermediate score, the authors recommend performing a nightly pulse oximetry to detect OSA patients.

Preoperative Evaluation: Estimation of Pulmonary Risk Including Obstructive Sleep Apnea Impact.

One in 4 deaths occurring within a week of surgery are related to pulmonary complications, making it the second most common serious morbidity after cardiovascular events. The most significant predictors of the postoperative pulmonary complications (PPCs) are American Society of Anesthesiologists physical status, advanced age, dependent functional status, surgical site, and duration of surgery. The overall risk of PPCs can be predicted using scores that incorporate readily available clinical data.

Sleep Study and Oximetry Parameters for Predicting Postoperative Complications in Patients With OSA.

In the surgical setting, OSA is associated with an increased risk of postoperative complications. At present, risk stratification using OSA-associated parameters derived from polysomnography (PSG) or overnight oximetry to predict postoperative complications have not been established. The objective of this narrative review is to evaluate the literature to determine the association between parameters extracted from in-laboratory PSG, portable PSG, or overnight oximetry and postoperative adverse events. Results: Preoperative apnea-hypopnea index (AHI) and measurements of nocturnal hypoxemia such as oxygen desaturation index (ODI), cumulative sleep time percentage with oxyhemoglobin saturation (SpO2) < 90% (CT90), minimum SpO2, mean SpO2, and longest apnea duration were associated with postoperative complications.

Non-steady State Modeling of the Ventilatory Depressant Effect of Remifentanil in Awake Patients Experiencing Moderate-to-severe Obstructive Sleep Apnea.

In this analysis the authors hypothesized that patients with moderate-to-severe obstructive sleep apnea are more sensitive to remifentanil-induced ventilatory depression than controls. Patients received a brief remifentanil infusion during continuous monitoring of ventilation, while minute ventilation was compared among 30 patients with moderate-to-severe obstructive sleep apnea diagnosed by polysomnography and 20 controls with no to mild obstructive sleep apnea per polysomnography. Obstructive sleep apnea status, apnea/hypopnea events per hour of sleep, or minimum nocturnal oxygen saturation measured by pulse oximetry did not influence the sensitivity to remifentanil-induced ventilatory depression in awake patients receiving a remifentanil infusion of 0.2 μg · kg of ideal body weight per minute.

Intraoperative ventilation settings and their associations with postoperative pulmonary complications in obese patients.

There is limited information concerning the current practice of intraoperative mechanical ventilation in obese patients, and the optimal ventilator settings for these patients are debated. The authors investigated intraoperative ventilation parameters and their associations with the development of postoperative pulmonary complications in 2,012 obese patients. Results: Obese patients are frequently ventilated with high tidal volume and low PEEP, and seldom receive recruitment maneuvers. Postoperative pulmonary complications increase hospital stay, and are associated with preoperative conditions, duration of anesthesia and intraoperative ventilation settings. Randomized trials are warranted to clarify the role of different ventilatory parameters in obese patients.

Patient preference survey: are patients willing to delay surgery if obstructive sleep apnea is suspected?

Screening and optimizing patients for OSA in the perioperative period may reduce postoperative complications. Despite controversy, there is a lack of studies with regard to the importance of shared decision-making and patient preferences in this context. It is unknown whether patients with suspected OSA, when given information about OSA, would be willing to delay surgery to diagnose and manage their condition preoperatively. This study consisted of a self-administered questionnaire that surveyed patients, patient relatives, or any accompanying members. The objective of this study was to determine whether respondents preferred to 1) proceed with surgery as planned, 2) delay surgery to ensure the medical condition of OSA is diagnosed and optimized, or 3) let his/her physician decide. Increasing emphasis and significant value has been placed on shared-decision making between patients and physicians. Educating patients about the risks of OSA and incorporating patient preferences into the perioperative management of OSA may be warranted.