Literature Updates from July 2019

Predictors of Delirium After Cardiac Surgery in Patients with Sleep-Disordered Breathing

Delirium ranks among the most common complications after cardiac surgery. This prospective observational study investigated risk factors for delirium in 141 patients undergoing cardiac surgery.

The presence of OSA was assessed with a portable sleep disordered breathing monitor the night before surgery. Delirium was examined with the validated Confusion Assessment Method for Intensive Care Units on the day of extubation and for a maximum of 3 days.

Multivariable logistic regression analysis showed that delirium was independently associated with age ≥70 years (OR 5.63, CI 1.79-17.68), central sleep apnea (OR 4.99, CI 1.41-17.69), and heart failure (OR 3.3, CI 1.06-10.35). Length of hospital stay, and time spent in the ICU/IMC were significantly longer for patients with delirium. In conclusion, central sleep apnea was independently associated with delirium amongst other established risk factors.

The Role of CPAP Treatment in Elderly Patients with Moderate Obstructive Sleep Apnea. A Multicenter Randomised Controlled Trial

In this open-label, randomized, multicenter study, 143 elderly patients (70 years or older) with moderate OSA were randomized to receive either CPAP (n=73) or no CPAP (n=72) for 3 months. The primary endpoint was the Epworth Sleepiness Scale (ESS), and secondary endpoints were quality of life, sleep-related symptoms, presence of anxiety or depression, office-based blood pressure, and some neurocognitive tests. They found that the CPAP group had better ESS scores, some sleep-related symptoms, and some dimensions of the quality of life questionnaire. However, there was no effect on the neurocognitive tests, including anxiety and depression or blood pressure levels. There was a positive correlation between the effects of CPAP and the improvement in EES values and quality of life domains.

Preoperative Sleep Questionnaires Identify Medical Emergency Team Activation in Older Adults.

The aim of this study was to assess the feasibility of utilizing OSA questionnaires in the preoperative clinic and to determine the frequency of postoperative medical emergency team activation among older patients at risk for OSA. Among 575 patients the use of preoperative, self-administered OSA questionnaires was feasible, while OSA risk was associated with the occurrence of postoperative medical emergency team activation among older adults. Therefore, the use of clinical tools and OSA questionnaires may improve preoperative risk stratification by predicting the requirement for postoperative medical emergency events particuarly in older patients.


Using Tracheal Breathing Sounds and Anthropometric Information for Screening Obstructive Sleep Apnoea During Wakefulness

Undiagnosed OSA significantly increases perioperative morbidity and mortality in patients undergoing surgery under general anesthesia. Tracheal breathing sound characteristics during wakefulness have shown a high correlation with the apnoea-hypopnea index (AHI), while they are also affected by anthropometric parameters, including sex, age, etc. In this study breathing sounds of 122 individuals (71 with AHI <15 as non-OSA and 51 with AHI > 15 as OSA) were recorded during wakefulness in supine position. The spectra and bi-spectra of 81 (47 non-OSA) individuals’ signals, which were randomly selected, were analyzed to extract the most significant features with the lowest sensitivity to the anthropometric parameters. Using a support vector machine (SVM) classifier, these features resulted in 72.1, 64.7 and 77.5% testing classification accuracy, sensitivity and specificity, respectively. Furthermore, the auhtors investigated classifying subjects into subgroups related to each anthropometric parameter and incorporating a voting procedure. This resulted in 83.6, 74.5 and 90.1% testing classification accuracy, sensitivity and specificity, respectively. The study indicated that it may possible to positively utilise the anthropometric information to enhance the classification accuracy for a reliable OSA screening procedure during wakefulness.

Outcomes and Complications After Spinal Fusion in Patients With Obstructive Sleep Apnea.

he aim of this retrospective analysis was to investigate the impact of OSA on perioperative complications, inpatient mortality, and cost in spinal fusion surgey.

Hospitalizations (2009-2011) were identified using the Nationwide Inpatient Sample.

Multivariable regression analysis demonstrated that OSA had a significant independent association with slightly increased respiratory (OR 1.13, CI 1.09-1.16), urinary and renal (OR 1.11, CI 1.07-1.16) or overall inpatient complications (OR 1.05, CI 1.02-1.05). OSA was also associated with lower inpatient mortality (OR 0.39, CI 0.33-0.45).

While OSA was associated with slightly higher inpatient complication rates it was not a predictor of inpatient mortality, which could hypothetically be based on the current implementation of perioperative OSA optimization and management strategies.

Perioperative Considerations and Anesthesia Management in Patients with Obstructive Sleep Apnea Undergoing Ophthalmic Surgery

Patients with OSA have an increased prevalence of ophthalmic disorders such as cataract, glaucoma, central serous retinopathy (detachment of retina, macular hole), eyelid laxity, keratoconus, and nonarteritic anterior ischemic optic neuropathy; some requiring surgery. Given that OSA is associated with a high incidence of perioperative complications and more than 80% of surgical patients with OSA are unrecognized, all surgical patients should be screened for OSA (eg, STOP-Bang questionnaire) with comorbid conditions identified and optimized. This is a literature review, highlighting best perioperative anesthesia practices in the management of ophthalmic surgical patients with OSA.

Obstructive Sleep Apnea Predicted by the STOP-BANG Questionnaire is Not Associated with Higher Rates of Post-Operative Complications Among a High-Risk Surgical Cohort

This study investigated whether OSA predicted by the STOP-BANG questionnaire would be associated with higher rates of post-operative cardiac, respiratory or neurological complications in a selected high-risk population with established major comorbidities undergoing major surgery.

In 310 patients, OSA as predicted by the STOP-BANG score was not associated with higher rates of post-operative complications in patients with major comorbidities undergoing high-risk surgery. As the findings from this cohort stand in contrast with other observational studies, more definitive studies are required to particuarly establish a causative link between OSA and post-operative complications in populations with higher perioperative risk from baseline.

Obesity and Obstructive Sleep Apnea in the Ambulatory Patient.

Obesity and OSA are often associated with increased perioperative risks and challenges for the anesthesiologist. This article addresses current controversies surrounding perioperative care of morbidly obese patients with or without OSA scheduled for ambulatory surgery, particularly in a free-standing ambulatory center. Topics discussed include preoperative selection of obese and OSA patients for ambulatory surgeries, intraoperative methods to reduce perioperative risk, and appropriate postoperative care.

Effect of Intraoperative High Positive End-Expiratory Pressure (PEEP) With Recruitment Maneuvers vs Low PEEP on Postoperative Pulmonary Complications in Obese Patients A Randomized Clinical Trial

The objective of this randomized trial was to determine whether a higher level of PEEP with alveolar recruitment maneuvers decreases postoperative pulmonary complications in obese patients undergoing surgery compared with lower levels of PEEP. A total of 2013 adults with a BMI of 35 or higher undergoing non-cardiac, non-neurological surgery under GA from 77 sites in 23 countries were included. Patients were randomized to a high level of PEEP of 12 cm H2O with alveolar recruitment maneuvers or to a low level of PEEP of 4 cm H2O. All patients received a tidal volume of 7ml/kg tidal volume. The primary outcome was a composite of pulmonary complications within the first 5 postoperative days including respiratory failure, acute respiratory distress syndrome, bronchospasm, new pulmonary infiltrates, pulmonary infection, aspiration pneumonitis, pleural effusion, atelectasis, cardiopulmonary edema, and pneumothorax. Secondary outcomes included intraoperative hypoxemia. There was no difference in the primary outcome 21.3% vs. 23.6% in the high PEEP vs. low PEEP group. Fewer patients had hypoxemia in the high vs. low PEEP group 5.0 vs. 13.6%, P<0.001). The authors concluded that an intraoperative mechanical ventilation strategy with a higher level of PEEP and alveolar recruitment maneuvers did not reduce postoperative pulmonary complications.

Outcomes and Safety Among Patients With Obstructive Sleep Apnea Undergoing Cancer Surgery Procedures in a Freestanding Ambulatory Surgical Facility.

The suitability of ambulatory surgery for patients with OSA remains controversial, while national guidelines call for more scientific evidence. This study retropsectively investigated the association between OSA status (STOP-BANG or diagnosis) and postoperative outcomes in ambulatory cancer surgery patients at the Josie Robertson Surgery Center of the Memorial Sloan Kettering Center. Surgeries included more complex ambulatory extended recovery procedures for which patients typically stay overnight, such as mastectomy, thyroidectomy, and minimally invasive hysterectomy, prostatectomy, and nephrectomy, as well as typical outpatient surgeries.

No difference was observed in length of stay regardless of OSA status or outpatient versus ambulatory extended recovery procedures. Though a greater frequency of postoperative respiratory events were reported in high-risk/diagnosed OSA patients, the rate of hospital transfer was not significantly different between the groups (risk difference, 0.78%; 95% CI, -0.43% to 2%). On multivariable analysis, there was no evidence of increased rate of urgent care center visits (adjusted risk difference, 1.4%; 95% CI, -0.68% to 3.4%; P = .15) or readmissions within 30 days (adjusted risk difference, 1.2%; 95% CI, -0.40% to 2.8%; P = .077) regardless of OSA status. These results support the notion that patients with moderate-to high-OSA risk, or diagnosed OSA can safely undergo outpatient and advanced ambulatory oncology surgery without the increased health care burden of extended stay or hospital admission while avoiding adverse postoperative outcomes.