The effects of labor on airway outcomes with Supreme™ laryngeal mask in women undergoing cesarean delivery under general anesthesia: a cohort study.

BACKGROUND: Pregnancy is associated with higher incidence of failed endotracheal intubation and is exacerbated by labor. However, the influence of labor on airway outcomes with laryngeal mask airway (LMA) for cesarean delivery is unknown. METHODS: This is a secondary analysis of a prospective cohort study on LMA use during cesarean delivery. Healthy parturients who fasted > 4 h undergoing Category 2 or 3 cesarean delivery with Supreme™ LMA (sLMA) under general anesthesia were included. We excluded parturients with BMI > 35 kg/m2, gastroesophageal reflux disease, or potentially difficult airway (Mallampati score of 4, upper respiratory tract or neck pathology). Anesthesia and airway management reflected clinical standard at the study center. After rapid sequence induction and cricoid pressure, sLMA was inserted as per manufacturer's recommendations. Our primary outcome was time to effective ventilation (time from when sLMA was picked up until appearance of end-tidal carbon dioxide capnography), and secondary outcomes include first-attempt insertion failure, oxygen saturation, ventilation parameters, mucosal trauma, pulmonary aspiration, and Apgar scores. Differences between labor status were tested using Student's t-test, Mann-Whitney U test, or Fisher's exact test, as appropriate. Quantitative associations between labor status and outcomes were determined using univariate logistic regression analysis. RESULTS: Data from 584 parturients were analyzed, with 37.8% in labor. Labor did not significantly affect time to effective ventilation (mean (SD) for labor: 16.0 (5.75) seconds; no labor: 15.3 (3.35); mean difference: -0.65 (95%CI: - 1.49 to 0.18); p = 0.1262). However, labor was associated with increased first-attempt insertion failure and blood on sLMA surface. No reduction in oxygen saturation or pulmonary aspiration was noted. CONCLUSIONS: Although no significant increase in time to effective ventilation was noted, labor may increase the number of insertion attempts and oropharyngeal trauma with sLMA use for cesarean delivery in parturients at low risk of difficult airway. Future studies should investigate the effects of labor on LMA use in high risk parturients. TRIAL REGISTRATION: The study was prospectively registered at clinicaltrials.gov ( NCT02026882 ) on 3 January 2014.

Association of Mallampati scoring on airway outcomes in women undergoing general anesthesia with Supreme™ laryngeal mask airway in cesarean section.

BACKGROUND: Obstetric dfficult airway is a leading cause of maternal morbidity and mortality. The laryngeal mask airway (LMA) is often used as a rescue airway device after failed intubation, however, little is known about predictors of difficult LMA insertion, particularly in obstetrics. Since Mallampati scores of III/IV has been associated with difficult tracheal intubation, our present study aims to investigate if Mallampati score (MP) could predict airway outcomes for LMA use in obstetrics. METHODS: This prospective cohort study was performed at a single-center: Quanzhou Women's and Children's Hospital, Fujian Province, China. Five hundred and eighty-four parturients undergoing elective cesarean section under general anesthesia were recruited. The primary outcome was time to effective ventilation, and secondary outcomes included first attempt insertion success, seal pressure, ventilation and hemodynamic parameters, occurrence of clinical aspiration, and maternal and fetal outcomes. RESULTS: The parturients were classified into two groups based on MP of III/IV (High MP: 61) versus I/II (Low MP: 523). BMI was higher in the High MP group than in the Low MP group (mean (SD) 29.3 (7.0) vs 26.8 (3.1), p <  0.0001). There was no difference in maternal age, ASA status and gestational age. There was similar time to effective ventilation (mean (SD) High MP: 14.9 (4.5) vs Low MP: 15.7 (4.4) seconds, p = 0.2172), and first attempt success rate, seal pressure, and peak airway pressure. No clinical aspiration was noted. The incidence of blood on SLMA was higher in the High MP group than in Low MP (4 (6.6%) vs 4 (0.8%), p = 0.001). There was no difference in sore throat, voice hoarseness, maternal satisfaction and fetal outcomes. CONCLUSION: High MP was not associated with reduced SLMA airway outcomes in cesarean section under general anesthesia, but may increase the risk of blood found on SLMA upon removal. TRIAL REGISTRATION: This study was registered at http://www.clinicaltrials.gov , identifier: NCT02026882 , retrospectively registered. Date of registration: December 31, 2013.