An update on preoperative assessment and preparation of surgical patients with obstructive sleep apnea.

PURPOSE OF REVIEW: There is a high prevalence of obstructive sleep apnea (OSA) in the surgical population, however, a significant proportion of patients are undiagnosed. The Society of Anesthesia and Sleep Medicine (SASM) has issued recent guidelines for preoperative assessment and preparation of patients with known or suspected OSA. The purpose of this review is to highlight key points in the new guidelines and explore the possibilities of different strategies in optimizing patients with OSA preoperatively. RECENT FINDINGS: Recent knowledge on phenotypes and endotypes has provided a better understanding of the disease and its underlying pathogenesis. Phenotypes refer to the predominant morphological characteristics of an individual whereas endotypes refer to the predominant underlying mechanism of the disease. Phenotypes and endotypes in OSA are heterogenous. Heterogeneity in the pathogenic mechanisms implies that opportunities other than the use of continuous positive airway pressure (CPAP) may exist to optimize or manage OSA patients preoperatively. SUMMARY: The prevalence of OSA in surgical patients is high. SASM has made recommendations in their published guidelines for the optimum preoperative preparation of patients with OSA. In the future, research may shift towards finding the underlying mechanism of OSA for targeted therapy.

Risk factors for opioid-induced respiratory depression and failure to rescue: a review.

PURPOSE OF REVIEW: The primary objective of this review is to identify the risk factors for opioid-induced respiratory depression (OIRD) in the postoperative period. RECENT FINDINGS: In the postoperative period, OIRD has often been reported resulting in morbidity and mortality. The risk factors which predispose surgical patients to increased risk of OIRD are not clearly defined. A literature search was performed for adult surgical patients who were prescribed opioids during their hospital stay and any available reports on postoperative respiratory depression/respiratory events. SUMMARY: Elderly, female sex, presence of obstructive sleep apnea, chronic obstructive pulmonary disease, cardiac disease, diabetes mellitus, hypertension, neurologic disease, renal disease, obesity, two or more comorbidities, opioid dependence, use of patient controlled analgesia, different routes of administration of opioids and concomitant administration of sedatives are significant risk factors for postoperative OIRD. The majority of patients with OIRD are deeply sedated and inadequately monitored. In patients with underlying risk factors, the dose of opioids should be carefully titrated. Enhanced monitoring of sedation level, respiratory rate, pulse oximetry and capnography is needed in the first 24 h after surgery.

Anesthetic Considerations for Patients With Congenital Central Hypoventilation Syndrome: A Systematic Review of the Literature.

Congenital central hypoventilation syndrome (CCHS) is a form of sleep-disordered breathing characterized by a diminished drive to breathe during sleep, despite progressive hypercapnia and hypoxia. The condition results from mutations in the paired-like homeobox 2B (PHOX2B) gene. The aim of this review was to conduct a systematic search of the current data on CCHS as it relates to perioperative considerations and to discuss the classification, prevalence, pathophysiology, presentation, genetics, and management of the condition. A systematic search of Medline, EMBASE, Cochrane Database of Systematic Reviews, and the Cochrane Central Register of Controlled Trials was done up to October 2015. The results were limited to human studies published in the English language. Study titles and abstracts were screened to identify studies relating to CCHS relevant to anesthetic care. All study designs including randomized controlled trials, observational studies, case reports, or case series were included. The searches yielded 165 articles, of which 45 were relevant to perioperative considerations. There were 15 relevant case reports categorized as pertaining to the following: (1) novel presentations of the condition after sedation/anesthesia; (2) anesthetic techniques used in patients with established CCHS; and (3) patients with CCHS who experienced anesthetic complications. Review of the case reports showed that patients ranged from neonates up to 59 years of age. Novel presentations of the disease after sedation or anesthesia for minor procedures often led to diagnosis. The sequelae of undiagnosed CCHS led to complications, such as hypoxia, desaturations, apneas, seizures, unplanned intensive care admissions, prolonged hospital stays, and long-term tracheostomies. There appeared to be few postoperative complications in patients with known CCHS. Anesthesiologists need to be aware of undiagnosed late-onset CCHS and include this condition in the differential diagnosis of patients with unexplained postoperative respiratory depression. Anesthetic techniques should minimize the use of agents that further depress respiration postprocedure and ensure adequate monitoring to detect postoperative apneas.

New supraglottic airway with built-in pressure indicator decreases postoperative pharyngolaryngeal symptoms: a randomized controlled trial.

PURPOSE: Excessive supraglottic airway cuff pressure increases postoperative pharyngolaryngeal symptoms such as sore throat, dysphonia, and dysphagia. A new supraglottic airway, AES Ultra CPV™ (CPV), has a built-in intracuff pressure indicator. We hypothesized that using the CPV would reduce postoperative symptoms when compared with the LMA Classic™ (LMA) without intracuff pressure guidance. METHODS: Ambulatory patients undergoing general anesthesia were randomized to either CPV or LMA. A size 3/4/5 was inserted according to manufacturer guidelines. Nitrous oxide was not used. In the LMA Group, the cuff was inflated according to manufacturer's guidelines. In the CPV Group, a CPV was inserted and the cuff inflated until the indicator was in the green zone (30-44 mmHg). Intracuff pressures were measured at five minutes and 20 min post-insertion in both groups. The primary outcome was the incidence of pharyngolaryngeal symptoms, defined as sore throat, dysphonia, and/or dysphagia at one, two, and/or 24 hr postoperatively. Continuous data were compared using Student's t test and categorical data were analyzed using Chi square analysis. RESULTS: The study included 170 patients, 85 per group. The mean (SD) intracuff pressure in the CPV group was significantly lower [44 (4) mmHg] than in the LMA Group [87 (37) mmHg]; P < 0.001. The incidence of pharyngolaryngeal symptoms was significantly lower in the CPV Group than in the LMA Group (26% vs 49%; P = 0.002). The absolute risk reduction was 24%, and the number-needed-to-treat was 4.3. CONCLUSION: The incidence of postoperative pharyngolaryngeal symptoms in the CPV Group with a cuff pressure-guided strategy was significantly lower than in the LMA Group with standard practice. ( CLINICAL TRIAL REGISTRATION NUMBER: NCT01800344).

A comparison between the Boussignac™ continuous positive airway pressure mask and the venturi mask in terms of improvement in the PaO2/F(I)O2 ratio in morbidly obese patients undergoing bariatric surgery: a randomized controlled trial.

PURPOSE: This study compared the Boussignac™ continuous positive airway pressure (CPAP) mask with the venturi face mask in terms of the postoperative PaO2/F(I)O2 (PF) ratio in morbidly obese patients after bariatric surgery. METHODS: Following hospital Research Ethics Board approval and written informed consent, morbidly obese (body mass index > 35 kg·m(-2)) patients undergoing bariatric surgery were recruited. The patients were anesthetized and laparoscopic Roux-en-Y gastric bypass was performed. Patients were assigned randomly to receive either the Boussignac (Boussignac Group) or the venturi face mask (Venturi Group) immediately after tracheal extubation. Patients were transported to the postanesthesia care unit, and the respective devices were applied for one hour. The PF ratio was recorded after tracheal intubation and at one hour and two hours post extubation. The percent forced expiratory volume (%FEV1) and the percent forced vital capacity (%FVC) were recorded preoperatively and at one hour and two hours post extubation. Independent Student's t tests were used for continuous variables, and the Chi square test was used for categorical variables. P < 0.05 was considered statistically significant. RESULTS: Eighty-one patients (Group Boussignac, n = 43; Group Venturi, n = 38) completed the study. Mean ages and body mass indices were similar in the two groups. At one hour post extubation, the PF ratio in the Boussignac Group was 361 (170) compared with 279 (91) in the Venturi Group (P = 0.007), and at two hours post extubation, the PF ratio in the Boussignac Group was 371 (162) compared with 323 (127) in the Venturi Group (P = 0.1). The postoperative %FEV(1) and %FVC were comparable in both groups at all time points. CONCLUSION: Compared with the venturi mask, the Boussignac CPAP mask improves the postoperative PF ratio in morbidly obese patients after bariatric surgery. The postoperative %FEV1 and %FVC are comparable for both groups.

Knowledge Gaps in the Perioperative Management of Adults with Obstructive Sleep Apnea and Obesity Hypoventilation Syndrome. An Official American Thoracic Society Workshop Report.

The purpose of this workshop was to identify knowledge gaps in the perioperative management of obstructive sleep apnea (OSA) and obesity hypoventilation syndrome (OHS). A single-day meeting was held at the American Thoracic Society Conference in May, 2016, with representation from many specialties, including anesthesiology, perioperative medicine, sleep, and respiratory medicine. Further research is urgently needed as we look to improve health outcomes for these patients and reduce health care costs. There is currently insufficient evidence to guide screening and optimization of OSA and OHS in the perioperative setting to achieve these objectives. Patients who are at greatest risk of respiratory or cardiac complications related to OSA and OHS are not well defined, and the effectiveness of monitoring and other interventions remains to be determined. Centers involved in sleep research need to develop collaborative networks to allow multicenter studies to address the knowledge gaps identified below.

Interventions in the preoperative clinic for long term smoking cessation: a quantitative systematic review.

PURPOSE: To assess the efficacy of interventions offered to patients in the preoperative clinic to promote long-term (> or = three months) smoking cessation following surgery. METHODS: We searched The Cochrane Library, MEDLINE, EMBASE and CINAHL for all randomized controlled trials (RCTs) on smoking-cessation interventions initiated in the preoperative clinic. Trial inclusion, quality assessment, and data extraction were performed independently by two authors. Standard meta-analytic techniques were applied. RESULTS: Four RCTs (n = 610 patients) were included in the review. Interventions included pharmacotherapy, counseling, educational literature and postoperative telephone follow-up. The follow-up period ranged between three to 12 months with only one RCT following up patients for > one year. Two studies used biochemical methods to validate subjects' self-reporting of smoking cessation at the follow-up assessment. Overall, the interventions were associated with a significantly higher cessation rate vs control at the three to six month follow-up period (pooled odds ratio: 1.58, 95% confidence interval (CI) 1.02-2.45, P value = 0.01, I(2) = 0%). The only trial with longer follow-up period (12 months), however, failed to show any significant difference between the intervention and control groups (odds ratio: 1.05, 95% CI 0.53-2.09, P value = 0.88). CONCLUSION: This systematic review suggests that smoking-cessation interventions initiated at the preoperative clinic can increase the odds of abstinence by up to 60% within a three- to six-month follow-up period. To evaluate the possibility of longer abstinence, future trials with at least one-year follow-up are recommended.

Cannot intubate-cannot ventilate and difficult intubation strategies: results of a Canadian national survey.

The purpose of this study was to determine the preferences of Canadian anesthesiologists in difficult intubation and cannot intubate-cannot ventilate (CICV) situations. Using a mailed survey, we asked anesthesiologists their preferences for and comfort level in using (a) alternative airway devices in a difficult intubation scenario and (b) infraglottic airway in a CICV scenario. Chi-square analysis and Student's t-test were used for categorical and continuous variables. Nine-hundred-seventy-one of 2066 surveys were returned. In the difficult intubation scenario, the preferred alternative airway devices were lighted stylet (45%), fiberoptic bronchoscope (26%), and intubating laryngeal mask airway (20%). Only 57% of respondents had encountered a CICV situation in real life. In the CICV scenario, preferred infraglottic airways were cricothyroidotomy by IV catheter (51%), percutaneous cricothyroidotomy (28%), and tracheostomy by surgeon (14%). Anesthesiologists had little experience and were uncomfortable with open surgical infraglottic airways. Anesthesiologists with experience using infraglottic airways on mannequins were more comfortable using them in patients (P < 0.001). In conclusion, in a difficult intubation scenario, the lighted stylet has emerged as the preferred alternative airway device. In a CICV scenario, respondents preferred cricothyroidotomy by IV catheter, followed by percutaneous cricothyroidotomy and tracheostomy by surgeon. Practice on mannequins was associated with improved comfort in using infraglottic airways in patients.

What is the minimum training required for successful cricothyroidotomy?: a study in mannequins.

BACKGROUND: A correctly performed cricothyroidotomy may be lifesaving in a cannot-ventilate, cannot-intubate situation. However, many practicing anesthesiologists do not have experience with cricothyroidotomy. The purpose of this study was to determine the minimum training required to perform cricothyroidotomy in 40 s or less in mannequins. METHODS: After informed consent, participants were shown a demonstration video and asked to perform 10 consecutive cricothyroidotomy procedures on a mannequin using a preassembled percutaneous dilational cricothyroidotomy set. Each attempt was timed from skin palpation to lung insufflation. Cricothyroidotomy was considered successful if it was performed in 40 s or less, and the cricothyroidotomy time was considered to have plateaued when there were no significant reductions in cricothyroidotomy times in three consecutive attempts. RESULTS: One hundred two anesthesiologists participated in the study. There was a significant reduction of cricothyroidotomy times over the 10 attempts (P < 0.0001) and between three consecutive attempts until the fourth attempt (P < 0.03). The cricothyroidotomy times plateaued by the fourth attempt, while the success rate plateaued at the fifth attempt (94, 96, 96, and 96% at the fourth, fifth, sixth, and seventh attempts, respectively). CONCLUSION: Practice on mannequins leads to reductions in cricothyroidotomy times and improvement in success rates. By the fifth attempt, 96% of participants were able to successfully perform the cricothyroidotomy in 40 s or less. While clinical correlates are not known, the authors recommend that providers of emergency airway management be trained on mannequins for at least five attempts or until their cricothyroidotomy time is 40 s or less. The most appropriate retraining intervals have yet to be determined for optimal cricothyroidotomy skill retention.