Perioperative considerations in the management of obstructive sleep apnoea

Identifying the pathophysiological traits of obstructive sleep apnea during dexmedetomidine sedation

Dexmedetomidine (DEX) has been described as a safe sedative in clinical practice, but its effects on the pathophysiological traits of obstructive sleep apnea (OSA) are unclear. We estimated the effects of DEX sedation on the four key pathophysiological traits of OSA (pharyngeal collapsibility, dilator muscle function, arousal threshold, and loop gain) in adult patients with OSA by conducting a secondary analysis of a prospective diagnostic trial. Pathophysiological traits estimated from polysomnography and the respiratory parameters under natural sleep and DEX-induced sleep were compared. Bivariate and multivariate linear regression analyses were used to estimate the relationship between pathophysiological traits and OSA severity for both sleep states. Adult patients with OSA had a significantly higher pharyngeal collapsibility (Vpassive: 44.9 [15.7 to 53.8] vs. 53.3 [34.2 to 66.3] %eupnea, p < 0.001), arousal threshold (178.5 [132.5 to 234.6] vs. 140.5 [123.2 to 192.3] %eupnea, p < 0.001), and loop gain (LG1: 0.74 ± 0.25 vs. 0.60 ± 0.17, p < 0.001; LGn: 0.52 ± 0.12 vs. 0.44 ± 0.08, p < 0.001) during DEX-induced sleep compared with natural sleep. There was no significant difference in dilator muscle function or PSG respiratory parameters between natural versus DEX-induced sleep states. Bivariate regression analysis showed varying degrees of correlation between OSA traits and severity. Multiple regression analysis indicated that collapsibility was the strongest predictor of the apnea-hypopnea index for both sleep states. Dexmedetomidine sedation in patients with OSA increased the pharyngeal collapsibility without impairing dilator muscle function, while elevating arousal threshold and increasing loop gain.

Acute Respiratory Failure Secondary to Low-Dose Opioid Administration in a Patient With Obstructive Sleep Apnea and Obesity Hypoventilation Syndrome After Undergoing Trans-sphenoidal Tumor Resection

We present a case of an obese 56-year-old male with obstructive sleep apnea (OSA), obesity hypoventilation syndrome (OHS), and pituitary macroadenoma, who underwent nasal endoscopic trans-sphenoidal resection. Surgery was performed under general anesthesia, uneventfully as planned. The patient experienced, however, delayed emergence despite receiving adequate neuromuscular blockade agent reversal. Extubation was performed and the patient was transferred to the recovery room on a Venturi mask (50% fraction of inspired oxygen, FIO2)and 93% saturation. Postoperatively, the patient was complaining of acute pain that did not resolve with non-opioid medications and a low morphine dose (0.035 mg/kg) for pain management was administered. Subsequently, he developed severe respiratory depression, requiring intubation. After three hours, the patient was extubated, transferred to the intensive care unit, and discharged five days later. Although the patient recovered favorably, this case highlights the risks of administering opioids to patients with OSA and OHS. To our knowledge, this is the first case reporting extreme respiratory depression secondary to the administration of a very low dose of morphine in patients with these comorbidities. Therefore, it is essential to be cautious with the use of opioids and to explore multimodal pain relief methods for these patients.

Machine Learning Algorithm to Perform the American Society of Anesthesiologists Physical Status Classification

OBJECTIVE

The American Society of Anesthesiologists (ASA) Physical Status (PS) Classification System defines perioperative patient scores ranging from 1 to 6 (healthy to brain dead, respectively). The scoring is performed and used by physician anesthesiologists and providers to classify surgical patients based on co-morbidities and various clinical characteristics. There is potentially a variability in scoring stemming from individual biases. The biases impact the prediction of operating times, length of stay in the hospital, anesthetic management, and billing. This study's purpose was to develop an automated system to achieve reproducible scoring.

METHODS

A machine learning (ML) model was trained on already assigned ASA PS scores of 12,064 patients. The ML algorithm was automatically selected by Wolfram Mathematica (Wolfram Research, Champaign, IL) and tested with retrospective records not used in training. Manual scoring was performed by the anesthesiologist as part of the standard preoperative evaluation. Intraclass correlation coefficient (ICC) in R (version 4.2.2; R Development Core Team, Vienna, Austria) was calculated to assess the consistency of scoring.

RESULTS

An ML model was trained on the data corresponding to 12,064 patients. Logistic regression was chosen automatically, with an accuracy of 70.3±1.0% against the training dataset. The accuracy against 1,999 patients (the test dataset) was 69.6±1.0%. The ICC for the comparison between ML and the anesthesiologists' ASA PS scores was greater than 0.4 ("fair to good").

CONCLUSIONS

We have shown the feasibility of applying ML to assess the ASA PS score within an oncology patient population. Though our accuracy was not very good, we feel that, as more data are mined, a valid foundation for refinement to ML will emerge.

Day-surgery adult patients with obesity and obstructive sleep apnea: Current controversies and concerns

Obesity and obstructive sleep apnea are considered independent risk factors that can adversely affect perioperative outcomes. A combination of these two conditions in the ambulatory surgery patient can pose significant challenges for the anesthesiologist. Nevertheless, these patients should not routinely be denied access to ambulatory surgery. Instead, patients should be appropriately optimized. Anesthesiologists and surgeons must work together to implement fast-track anesthetic and surgical techniques that will ensure successful ambulatory outcomes.

Nocturnal Hypoventilation in the Patients Submitted to Thoracic Surgery

Introduction

Nocturnal hypoventilation may occur due to obesity, concomitant chronic obstructive pulmonary disease (COPD), obstructive sleep apnea, and/or the use of narcotic analgesics. The aim of the study was to evaluate the risk and severity of nocturnal hypoventilation as assessed by transcutaneous continuous capnography in the patients submitted to thoracic surgery.

Materials and Methods

The material of the study consisted of 45 obese (BMI 34.8 ± 3.7 kg/m2) and 23 nonobese (25.5 ± 3.6 kg/m2) patients, who underwent thoracic surgery because of malignant (57 patients) and nonmalignant tumors. All the patients received routine analgesic treatment after surgery including intravenous morphine sulfate. Overnight transcutaneous measurements of CO2 partial pressure (tcpCO2) were performed before and after surgery in search of nocturnal hypoventilation, i.e., the periods lasting at least 10 minutes with tcpCO2 above 55 mmHg.

Results

Nocturnal hypoventilation during the first night after thoracic surgery was detected in 10 patients (15%), all obese, three of them with COPD, four with high suspicion of moderate-to-severe OSA syndrome, and one with chronic daytime hypercapnia. In the patients with nocturnal hypoventilation, the mean tcpCO2 was 53.4 ± 6.1 mmHg, maximal tcpCO2 was 59.9 ± 8.4 mmHg, and minimal tcpCO2 was 46.4 ± 6.7 mmHg during the first night after surgery. In these patients, there were higher values of minimal, mean, and maximal tcpCO2 in the preoperative period. Nocturnal hypoventilation in the postoperative period did not influence the duration of hospitalization. Among 12 patients with primary lung cancer who died during the first two years of observation, there were 11 patients without nocturnal hypoventilation in the early postoperative period.

Conclusion

Nocturnal hypoventilation may occur in the patients after thoracic surgery, especially in obese patients with bronchial obstruction, obstructive sleep apnea, or chronic daytime hypercapnia, and does not influence the duration of hospitalization.

Preoperative risk evaluation and perioperative management of patients with obstructive sleep apnea: a narrative review

Obstructive sleep apnea (OSA) is a common sleep-breathing disorder associated with significant comorbidities and perioperative complications. This narrative review is aimed at comprehensively overviewing preoperative risk evaluation and perioperative management strategies for patients with OSA. OSA is characterized by recurrent episodes of upper airway obstruction during sleep leading to hypoxemia and arousal. Anatomical features, such as upper airway narrowing and obesity, contribute to the development of OSA. OSA can be diagnosed based on polysomnography findings, and positive airway pressure therapy is the mainstay of treatment. However, alternative therapies, such as oral appliances or upper airway surgery, can be considered for patients with intolerance. Patients with OSA face perioperative challenges due to difficult airway management, comorbidities, and effects of sedatives and analgesics. Anatomical changes, reduced upper airway muscle tone, and obesity increase the risks of airway obstruction, and difficulties in intubation and mask ventilation. OSA-related comorbidities, such as cardiovascular and respiratory disorders, further increase perioperative risks. Sedatives and opioids can exacerbate respiratory depression and compromise airway patency. Therefore, careful consideration of alternative pain management options is necessary. Although the association between OSA and postoperative mortality remains controversial, concerns exist regarding adverse outcomes in patients with OSA. Understanding the pathophysiology of OSA, implementing appropriate preoperative evaluations, and tailoring perioperative management strategies are vital to ensure patient safety and optimize surgical outcomes.

Demonstration of Accuracy and Feasibility of Remotely Delivered Oximetry: A Blinded, Controlled, Real-World Study of Regional/Rural Children with Obstructive Sleep Apnoea

Objectives: Evaluate diagnostic accuracy and feasibility of a mail-out home oximetry kit. Design: Patients were referred for both the tertiary/quaternary-centre hospital-delivered oximetry (HDO) and for the mail-out remotely-delivered oximetry (RDO). Quantitative and qualitative data were collected. The COVID-19 pandemic began during this study; therefore, necessary methodological adjustments were implemented. Setting: Patients were first evaluated in Swan Hill, Victoria. RDO kits were sent to home addresses. For the HDO, patients travelled to the Melbourne city area, received the kit, stayed overnight, and returned the kit the following morning. Participants: All consecutive paediatric patients (aged 2−18), diagnosed by a specialist in Swan Hill with obstructive sleep apnoea (OSA) on history/examination, and booked for tonsillectomy +/− adenoidectomy, were recruited. Main outcome measures: Diagnostic accuracy (i.e., comparison of RDO to HDO results) and test delivery time (i.e., days from consent signature to oximetry delivery) were recorded. Patient travel distances for HDO collection were calculated using home/delivery address postcodes and Google® Maps data. Qualitative data were collected with two digital follow-up surveys. Results: All 32 patients that had both the HDO and RDO had identical oximetry results. The HDO mean delivery time was 87.7 days, while the RDO mean delivery time was 23.6 days (p value: <0.001). Qualitatively, 3/28 preferred the HDO, while 25/28 preferred the RDO (n = 28). Conclusions: The remote option is as accurate as the hospital option, strongly preferred by patients, more rapidly completed, and also an ideal investigation delivery method during certain emergencies, such as the COVID-19 pandemic.

Reliability of STOP-Bang questionnaire and pulse oximetry as predictors of OSA - a retrospective study

OBJECTIVE

To verify the reliability of a STOP-Bang questionnaire and objective blood oxygen concentration (SpO2) estimation by pulse oximetry as an indicator of patients' vulnerability to OSA, by correlating data of these two tests with that of the "gold standard" all-night polysomnography.

METHODS

STOP-Bang score and pulse oximetry value (SpO2) for each patient were tabulated against the total sleep AHI score (obtained from subsequent all-night polysomnography) and analyzed to evaluate the diagnostic accuracy of the STOP-Bang questionnaire and pulse oximetry.

RESULTS

With sensitivity and specificity scores of 91.2% and 88.6%, respectively, positive predictive value 90.5%, negative predictive value 40.2%, the twin diagnostic test (STOP-Bang and pulse oximetry) was found to be highly congruent with the polysomnography (PSG), achieving a diagnostic accuracy of 85%.

CONCLUSION

Dental chairside screening by STOP-Bang questionnaire and pulse oximetry would be a good option, especially where logistic and economic constraints impede all-night polysomnography.

Clinical implications of opioid-induced ventilatory impairment

Opioid-induced ventilatory impairment is the primary mechanism of harm from opioid use. Opioids suppress the activity of the central respiratory centres and are sedating, leading to impairment of alveolar ventilation.Respiratory physiological changes induced with acute opioid use include depression of the hypercapnic ventilatory response and hypoxic ventilatory response. In chronic opioid use a compensatory increase in hypoxic ventilatory response maintains ventilation and contributes to the onset of sleep-disordered breathing patterns of central sleep apnoea and ataxic breathing. Supplemental oxygen use in those at risk of opioid-induced ventilatory impairment requires careful consideration by the clinician to prevent failure to detect hypoventilation, if oximetry is being relied on, and the overriding of hypoxic ventilatory drive. Obstructive sleep apnoea and opioid-induced ventilatory impairment are frequently associated, with this interrelationship being complex and often unpredictable. Monitoring the patient for opioid-induced ventilatory impairment poses challenges in the areas of reliability, avoidance of alarm fatigue, cost, and personnel demands. Many situations remain in which patients cannot be provided effective analgesia without opioids, and for these the clinician requires a comprehensive knowledge of opioid-induced ventilatory impairment.

Surgical management of obstructive sleep apnoea: A position statement of the Australasian Sleep Association. Respirology 2020;25:1292-1308. [PMID: 33190389 PMCID: PMC7839593 DOI: 10.1111/resp.13967]

Surgery for adult obstructive sleep apnoea (OSA) plays a key role in contemporary management paradigms, most frequently as either a second‐line treatment or in a facilitatory capacity. This committee, comprising two sleep surgeons and three sleep physicians, was established to give clarity to that role and expand upon its appropriate use in Australasia. This position statement has been reviewed and approved by the Australasian Sleep Association (ASA) Clinical Committee.

Enhanced Recovery and Surgical Optimization Protocol for Minimally Invasive Gynecologic Surgery: An AAGL White Paper

This is the first Enhanced Recovery After Surgery (ERAS) guideline dedicated to standardizing and optimizing perioperative care for women undergoing minimally invasive gynecologic surgery. The guideline was rigorously formulated by an American Association of Gynecologic Laparoscopists Task Force of US and Canadian gynecologic surgeons with special interest and experience in adapting ERAS practices for patients requiring minimally invasive gynecologic surgery. It builds on the 2016 ERAS Society recommendations for perioperative care in gynecologic/oncologic surgery by serving as a more comprehensive reference for minimally invasive endoscopic and vaginal surgery for both benign and malignant gynecologic conditions. For example, the section on preoperative optimization provides more specific recommendations derived from the ambulatory surgery and anesthesia literature for the management of anemia, hyperglycemia, and obstructive sleep apnea. Recommendations pertaining to multimodal analgesia account for the recent Food and Drug Administration warnings about respiratory depression from gabapentinoids. The guideline focuses on workflows important to high-value care in minimally invasive surgery, such as same-day discharge, and tackles controversial issues in minimally invasive surgery, such as thromboprophylaxis. In these ways, the guideline supports the American Association of Gynecologic Laparoscopists and our collective mission to elevate the quality and safety of healthcare for women through excellence in clinical practice.