POST-OPERATIVE VENTILATION PATTERNS AND THE EFFECTS OF NON-INVASIVE POSITIVE PRESSURE THERAPY ON VENTILATORY CHANGES AS MEASURED BY A NON-INVASIVE IMPEDANCE DEVICE IN PATIENTS WITH OBSTRUCTIVE SLEEP APNEA

Abstract

Patients undergoing general anesthesia who have or are suspected of obstructive sleep apnea (OSA) may be at increased risk for ventilatory complications, including respiratory depression, airway obstructions, and apnea events. The increased prevalence of OSA in the surgical population has led clinicians and researchers to explore strategies to screen for OSA and employ best management practices to minimize perioperative respiratory events. Standardized monitors in the postoperative anesthesia care unit (PACU) may have limited utility in this patient population to readily detect real or potential airway complications. The purposes of this prospective observational study were: to further explore the relationship of OSA risk to perioperative events in participants undergoing laparoscopic gastric bypass surgery (GBS); explore the utility of using an innovate respiratory volume monitor (RVM, ExSpironTM, Waltham, MA, USA) to identify reduced ventilatory function before standard postoperative monitors alert nurses of hypoventilation or apnea events; measure the ventilatory changes when noninvasive positive pressure therapy (NPPV) was applied in the PACU using the RVM. A prospective convenience sample of 50 adult participants with 25 assigned as "mild OSA" (M-OSA) and 25 in the "moderate/severe OSA" (S-OSA) were selected and observed in the PACU to explore the research questions. Findings included no differences perioperative outcomes with the exception of longer PACU stay mean times for the M-OSA, despite S-OSA group being older, having larger neck circumferences, and receiving more opioids in the PACU. The RVM identified respiratory depression events earlier and more often than decreases in pulse oximetry. Thirteen participants who received NPPV and had no significant change in minute ventilation (MV) during use, however a mean decrease of 25% in tidal volume (TV) was measured from mask removal time to five-minute post removal period. This supports the effects of NPPV on maintaining MV when measured by RVM. Findings of the study help support the need to further explore the utility of using RVM to measure ventilatory function, guide therapies, and incorporate RVM into practice settings where patient populations are at risk for respiratory complications. The use of postoperative NPPV therapy needs further exploration in randomized studies to identify optimal NPPV type, pressure settings, and duration of use to help improve ventilatory function in patients known to or suspected of having OSA.