Incidence of Postoperative Respiratory Depression and Postoperative Apnea in the Obese General Surgical Population.

SESSION TITLE: Patient Safety Initiative PostersSESSION TYPE: Original Investigation PosterPRESENTED ON: Wednesday, October 29, 2014 at 01:30 PM - 02:30 PMPURPOSE: According to the CDC, obstructive sleep apnea (OSA) occurs in 1 in 4 men and 1 in 10 women in the US. The prevalence increases in the obese population and OSA is a risk factor for post-operative respiratory complications. Current post-operative monitoring does not provide quantitative measurements of ventilation and the true incidence of post-operative respiratory depression (PORD) and apnea (POA) is unknown. Accurately determining the incidence and risk associated with PORD and POA is especially important post-operatively where the use of opioids for pain management and other respiratory depressants is prevalent. We examined the incidence of POA and PORD in an obese population using a non-invasive respiratory volume monitor (RVM) and analyzed additional risk factors.

METHODS: Following IRB approval and written informed consent, RVM traces were obtained from obese patients (BMI>35kg/m2) undergoing elective surgery, using an electrode PadSet on the thorax, beginning pre-operatively until PACU discharge. Demographic data, medical history and STOP-Bang scores were collected. An apneic event was defined as no detected breaths for >10sec. POA was defined as >5 apneic events per hour. The lowest minute ventilation (MV) in the PACU (5 min avg) was identified, and an MV of <40% predicted was defined as PORD. Data were analyzed with a 2-tailed t-test to determine the association of BMI, age, STOP-Bang, OSA, sex, diabetes, asthma, CHF and CAD with POA and PORD.

RESULTS: 80 patients (age 47±12 yrs; BMI 43±7 kg/m2) were studied. The incidence of POA was 31% (n=25) and PORD 15 % (n=12). There was no significant association between PORD and the variables studied. Age was the single variable significantly associated with POA (p< 0.01). STOP-Bang scores were not different between groups with and without POA or PORD (POA: 4.9, 4.3; PORD: 4.6, 4.5). Preoperative diagnosis of OSA was not associated with a higher incidence of POA or PORD.CONCLUSIONS: In this study, only age was significantly associated with POA, which was not the case for other criteria previously believed to be linked to an increased incidence of POA and PORD in the PACU. The influence of factors such as type of anesthesia and PACU pain management should be examined in future studies, as well as outcomes beyond the recovery room stay.CLINICAL IMPLICATIONS: The use of RVM to quantify POA and PORD post-operatively has the potential for individualized patient care. The use of RVM to identify patients with POA and PORD in the PACU may improve patient safetyDISCLOSURE: C. Marshall MacNabb: Employee: Respiratory Motion, Inc. The following authors have nothing to disclose: Srikanth Sridhar, Evan Pivalizza, Julie Kim, Iwona Bonney, Roman SchumannNo Product/Research Disclosure Information.