RESUMO
PURPOSE: Severity of hypoxemic events resulting from obstructive sleep apnea (OSA) is correlated with increased risk of complications and sudden death. We studied the use of a peripheral transcutaneous electrical stimulus (TES) on the magnitude and duration of sleep apnea associated hypoxemia in postoperative patients at high risk for OSA. METHODS: In this randomized, double-blind, controlled, single-centre trial, 106 adult patients undergoing elective surgery who were at medium to high risk for OSA (sleep apnea clinical scores of 18-35) were randomized to either TES (active stimulus group, n = 53) or control (non-stimulus group, n = 53) during their stay in the postanesthesia care unit. Transcutaneous electrical stimuli were delivered at threshold oxygen saturation measurements (SpO2) ≤ 93%. The primary endpoint was the SpO2 area under the curve (AUC) < 90%. Secondary endpoints included the percentage of patients with SpO2 < 90%, duration SpO2 < 90%, lowest SpO2 in the first hour, and adverse events associated with TES. RESULTS: Compared with controls (n = 45), those in the active group (n = 34) showed a decreased SpO2 AUC < 90% (median 0.0 vs 15.2 % sec, respectively; P = 0.009), a smaller percentage of subjects with SpO2 < 90% (47% active vs 71% control; P = 0.03), a shorter duration of SpO2 < 90% (median 0.0 vs 19.1 sec, respectively; P = 0.01), and a higher nadir of SpO2 recorded during the first hour (median 90.5% vs 87.9%, respectively; P = 0.04). Among patients with at least one SpO2 < 93%, there were fewer with SpO2 < 90% in the active group (55% vs 84%, respectively; P = 0.009). No adverse events related to TES were reported. CONCLUSION: In postoperative surgical patients at risk for OSA, peripheral transcutaneous electrical stimulation applied during apneic episodes decreased the duration and magnitude of hypoxemia. TRIAL REGISTRATION: www.ClinicalTrials.gov (NCT02554110); registered 18 September, 2015.