Obstructive sleep apnea is not a risk factor for difficult intubation in morbidly obese patients

BACKGROUND: Morbid obesity (MO), obstructive sleep apnea (OSA), and neck circumference (NC) are widely believed to be independent risk factors for difficult tracheal intubation. In this study, we sought to determine whether these factors were associated with increased risk of difficult intubation in patients undergoing bariatric surgery. The predictive factors tested were OSA and its severity, as determined by apnea-hypopnea index (AHI), gender, NC, and body mass index (BMI). METHODS: All sequentially enrolled MO patients underwent preoperative polysomnography. Severity of OSA was quantified using AHI and the American Society of Anesthesiologists' OSA severity scale. All patients had a standardized anesthetic that included positioning in the "ramped position" for direct laryngoscopy. RESULTS: One hundred eighty consecutive patients were recruited, 140 women and 40 men. The incidence of OSA was 68%. The mean BMI was 49.4 kg/m(2). The mean AHI was 31.3 (range, 0-135). All the patients' tracheas were intubated successfully without the aid of rescue airways by anesthesiology residents. Six patients required three or more intubation attempts, a difficult intubation rate of 3.3%. There was an 8.3% incidence of difficult laryngoscopy, defined as a Cormack and Lehane Grade 3 or 4 view. There was no relationship between NC and difficult intubation (odds ratio 1.02, 95% confidence interval 0.93-1.1), between the diagnosis of OSA and difficult intubation (P = 0.09), or between BMI and difficult intubation (odds ratio 0.99, 95% confidence interval 0.92-1.06, P = 0.8). There was no relationship between number of intubation attempts and BMI (P = 0.8), AHI (P = 0.82), or NC (P = 0.3). Mallampati Grade III or more predicted difficult intubation (P = 0.02), as did male gender (P = 0.02). Finally, there was no relationship between Cormack and Lehane grade and BMI (P = 0.88), AHI (P = 0.93), or OSA (P = 0.6). Increasing NC was associated with difficult laryngoscopy but not difficult intubation (P 0.02). CONCLUSIONS: In MO patients undergoing bariatric surgery in the "ramped position," there was no relationship between the presence and severity of OSA, BMI, or NC and difficulty of intubation or laryngoscopy grade. Only a Mallampati score of 3 or 4 or male gender predicted difficult intubation. (Anesth Analg 2009;109:1182-6

Obstructive sleep apnea is not a risk factor for difficult intubation in morbidly obese patients

BACKGROUND: Morbid obesity (MO), obstructive sleep apnea (OSA), and neck circumference (NC) are widely believed to be independent risk factors for difficult tracheal intubation. In this study, we sought to determine whether these factors were associated with increased risk of difficult intubation in patients undergoing bariatric surgery. The predictive factors tested were OSA and its severity, as determined by apnea-hypopnea index (AHI), gender, NC, and body mass index (BMI). METHODS: All sequentially enrolled MO patients underwent preoperative polysomnography. Severity of OSA was quantified using AHI and the American Society of Anesthesiologists\u27 OSA severity scale. All patients had a standardized anesthetic that included positioning in the "ramped position" for direct laryngoscopy. RESULTS: One hundred eighty consecutive patients were recruited, 140 women and 40 men. The incidence of OSA was 68%. The mean BMI was 49.4 kg/m(2). The mean AHI was 31.3 (range, 0-135). All the patients\u27 tracheas were intubated successfully without the aid of rescue airways by anesthesiology residents. Six patients required three or more intubation attempts, a difficult intubation rate of 3.3%. There was an 8.3% incidence of difficult laryngoscopy, defined as a Cormack and Lehane Grade 3 or 4 view. There was no relationship between NC and difficult intubation (odds ratio 1.02, 95% confidence interval 0.93-1.1), between the diagnosis of OSA and difficult intubation (P = 0.09), or between BMI and difficult intubation (odds ratio 0.99, 95% confidence interval 0.92-1.06, P = 0.8). There was no relationship between number of intubation attempts and BMI (P = 0.8), AHI (P = 0.82), or NC (P = 0.3). Mallampati Grade III or more predicted difficult intubation (P = 0.02), as did male gender (P = 0.02). Finally, there was no relationship between Cormack and Lehane grade and BMI (P = 0.88), AHI (P = 0.93), or OSA (P = 0.6). Increasing NC was associated with difficult laryngoscopy but not difficult intubation (P 0.02). CONCLUSIONS: In MO patients undergoing bariatric surgery in the "ramped position," there was no relationship between the presence and severity of OSA, BMI, or NC and difficulty of intubation or laryngoscopy grade. Only a Mallampati score of 3 or 4 or male gender predicted difficult intubation. (Anesth Analg 2009;109:1182-6

Atrial fibrillation after aortic arch repair requiring deep hypothermic circulatory arrest: incidence, clinical outcome, and clinical predictors.

OBJECTIVE: To delineate the incidence, outcome impact, and clinical predictors of atrial fibrillation (AF) after adult aortic arch repair requiring deep hypothermic circulatory arrest (AAR-DHCA) AIMS: To determine the incidence of AF after AAR-DHCA, to determine whether AF after AAR-DHCA affects mortality or stay in the intensive care unit (ICU), to determine multivariate predictors for AF after AAR-DHCA, and to determine whether aprotinin protects against AF after AAR-DHCA. STUDY DESIGN: Retrospective and observational. STUDY SETTING: Single large university hospital. PARTICIPANTS: All adults undergoing AAR-DHCA in 2000 and 2001. MAIN RESULTS: The cohort size was 144. Antifibrinolytic exposure was 100%, aprotinin 66% and aminocaproic acid 34%. The incidence of AF was 34.0%. AF was not significantly associated with increased mortality or prolonged ICU stay. Advanced age was a multivariate risk factor for AF. Lower temperature nadir during DHCA was protective against postoperative AF. Aprotinin had no demonstrable effect on AF after AAR-DHCA. CONCLUSIONS: AF after AAR-DHCA is common but does not independently increase mortality or ICU stay. The risk of AF after AAR-DHCA increases with age but decreases with the degree of hypothermia during DHCA. Aprotinin does not appear to affect the risk of AF after AAR-DHCA

Continuous positive airway pressure via the boussignac system immediately after extubation improves lung function in morbidly obese patients with obstructive sleep apnea undergoing laparoscopic bariatric surgery

Background: Morbidly obese patients are at elevated risk of perioperative pulmonary complications, including airway obstruction and atelectasis. Continuous positive airway pressure may improve postoperative lung mechanics and reduce postoperative complications in patients undergoing abdominal surgery. Methods: Forty morbidly obese patients with known obstructive sleep apnea undergoing laproscopic bariatric surgery with standardized anesthesia care were randomly assigned to receive continuous positive airway pressure via the Boussignac system immediately after extubation (Boussignac group) or supplemental oxygen (standard care group). All subjects had continuous positive airway pressure initiated 30 min after extubation in the postanesthesia care unit via identical noninvasive ventilators. The primary outcome was the relative reduction in forced vital capacity from baseline to 24 h after extubation. Results: Forty patients were enrolled into the study, 20 into each group. There were no significant differences in baseline characteristics between the groups. The intervention predicted less reduction in all measured lung functions: forced expiratory volume in 1 s (coefficient 0.37, SE 0.13, P = 0.003, CI 0.13-0.62), forced vital capacity (coefficient 0.39, SE 0.14, P = 0.006, CI 0.11-0.66), and peak expiratory flow rate (coefficient 0.82, SE 0.31, P = 0.008, CI 0.21-0.1.4). Conclusions: Administration of continuous positive airway pressure immediately after extubation maintains spirometric lung function at 24 h after laparoscopic bariatric surgery better than continuous positive airway pressure started in the postanesthesia care unit

Noninvasive ventilation immediately after extubation improves lung function in morbidly obese patients with obstructive sleep apnea undergoing laparoscopic bariatric surgery

BACKGROUND: Noninvasive positive pressure ventilation (NIPPV) may improve postoperative lung function and reduce postoperative complications in patients undergoing abdominal surgery. The purpose of our study was to determine whether the timing of postoperative NIPPV affects lung function 1 day postoperatively. METHODS: Forty morbidly obese patients with known obstructive sleep apnea undergoing laparoscopic bariatric surgery with standardized anesthesia care were randomly assigned to receive NIPPV immediately after tracheal extubation (immediate group) or supplemental oxygen (standard group). All patients had continuous positive airway pressure initiated 30 minutes after extubation in the postanesthesia care unit (PACU) via identical noninvasive ventilators. Spirometry was performed by a blinded observer in the perioperative holding area 1 hour after admission to the PACU and 1 day postoperatively. The primary outcome was the change in forced vital capacity (FVC) from baseline to 24 hours (FVC baseline-FVC 24 hours). RESULTS: Forty patients, 20 in each group, were enrolled in the study. Forced expiratory volume in 1 second, FVC, and peak expiratory flow rate were significantly reduced in both groups from perioperative values throughout the study. At 24 hours, the intervention group had lost only 0.7 L FVC, versus 1.3 L for the intervention group (P = 0.0005). An analysis of covariance confirmed this and indicated that the immediate postoperative NIPPV better preserved spirometric function at 1 and 24 hours postoperatively. Specifically, the differences in the primary outcome were statistically significant. CONCLUSIONS: NIPPV given immediately after extubation significantly improves spirometric lung function at 1 hour and 1 day postoperatively, compared with continuous positive airway pressure started in the PACU, in morbidly obese patients with obstructive sleep apnea undergoing laparoscopic bariatric surgery. (Anesth Ana Ig 2010;110:1360-5

Continuous positive airway pressure via the boussignac system immediately after extubation improves lung function in morbidly obese patients with obstructive sleep apnea undergoing laparoscopic bariatric surgery

Background: Morbidly obese patients are at elevated risk of perioperative pulmonary complications, including airway obstruction and atelectasis. Continuous positive airway pressure may improve postoperative lung mechanics and reduce postoperative complications in patients undergoing abdominal surgery. Methods: Forty morbidly obese patients with known obstructive sleep apnea undergoing laproscopic bariatric surgery with standardized anesthesia care were randomly assigned to receive continuous positive airway pressure via the Boussignac system immediately after extubation (Boussignac group) or supplemental oxygen (standard care group). All subjects had continuous positive airway pressure initiated 30 min after extubation in the postanesthesia care unit via identical noninvasive ventilators. The primary outcome was the relative reduction in forced vital capacity from baseline to 24 h after extubation. Results: Forty patients were enrolled into the study, 20 into each group. There were no significant differences in baseline characteristics between the groups. The intervention predicted less reduction in all measured lung functions: forced expiratory volume in 1 s (coefficient 0.37, SE 0.13, P = 0.003, CI 0.13-0.62), forced vital capacity (coefficient 0.39, SE 0.14, P = 0.006, CI 0.11-0.66), and peak expiratory flow rate (coefficient 0.82, SE 0.31, P = 0.008, CI 0.21-0.1.4). Conclusions: Administration of continuous positive airway pressure immediately after extubation maintains spirometric lung function at 24 h after laparoscopic bariatric surgery better than continuous positive airway pressure started in the postanesthesia care unit

Cardiopulmonary bypass, hemolysis, and nitroprusside-induced cyanide production.

BACKGROUND: Cyanide toxicity is a complication of sodium nitroprusside administration. Cardiac surgery may increase the risk of cyanide toxicity, because hemolysis during cardiopulmonary bypass (CPB) may catalyze the release of free cyanide from sodium nitroprusside. METHODS: We obtained serial blood specimens from 25 cardiac surgical patients during CPB. Plasma specimens were analyzed for free hemoglobin concentration and ability to generate free cyanide anion upon exposure to sodium nitroprusside. RESULTS: Hemolysis based on plasma-free hemoglobin concentration increased over time during CPB at an average rate of 0.27 mg x dL(-1) x min(-1) (P \u3c 0.001). The concentration of free cyanide generated by the addition of sodium nitroprusside to the plasma samples was directly related to the plasma-free hemoglobin concentration (P \u3c 0.001). CONCLUSION: CPB-associated hemolysis and free hemoglobin release accelerated the immediate release of free cyanide from sodium nitroprusside. These in vitro findings suggest that cardiac surgical patients may be at increased risk of cyanide toxicity in response to the perioperative administration of sodium nitroprusside

Continuous positive airway pressure via the boussignac system immediately after extubation improves lung function in morbidly obese patients with obstructive sleep apnea undergoing laparoscopic bariatric surgery

Background: Morbidly obese patients are at elevated risk of perioperative pulmonary complications, including airway obstruction and atelectasis. Continuous positive airway pressure may improve postoperative lung mechanics and reduce postoperative complications in patients undergoing abdominal surgery. Methods: Forty morbidly obese patients with known obstructive sleep apnea undergoing laproscopic bariatric surgery with standardized anesthesia care were randomly assigned to receive continuous positive airway pressure via the Boussignac system immediately after extubation (Boussignac group) or supplemental oxygen (standard care group). All subjects had continuous positive airway pressure initiated 30 min after extubation in the postanesthesia care unit via identical noninvasive ventilators. The primary outcome was the relative reduction in forced vital capacity from baseline to 24 h after extubation. Results: Forty patients were enrolled into the study, 20 into each group. There were no significant differences in baseline characteristics between the groups. The intervention predicted less reduction in all measured lung functions: forced expiratory volume in 1 s (coefficient 0.37, SE 0.13, P = 0.003, CI 0.13-0.62), forced vital capacity (coefficient 0.39, SE 0.14, P = 0.006, CI 0.11-0.66), and peak expiratory flow rate (coefficient 0.82, SE 0.31, P = 0.008, CI 0.21-0.1.4). Conclusions: Administration of continuous positive airway pressure immediately after extubation maintains spirometric lung function at 24 h after laparoscopic bariatric surgery better than continuous positive airway pressure started in the postanesthesia care unit