Abstract 15815: Developing a Protocol Utilizing Non-Invasive Respiratory Volume Monitoring to Identify Patients at Risk for Opioid Induced Respiratory Depression
Introduction: Respiratory compromise, often due to opioid administration, is a contributor or main cause of >1/3 of hospital cardiopulmonary arrests. Opioids are routinely used for pain management postoperatively, and adequate respiratory monitoring remains a major challenge. A non-invasive Respiratory Volume Monitor (RVM) that displays continuous, real-time, minute ventilation (MV), tidal volume (TV) & respiratory rate (RR) measurements now provides an alternative to subjective evaluation & oximetry for assessment of respiratory status. An RVM based risk assessment protocol was developed to identify patients at risk for respiratory depression following opioid administration.
Methods: Respiratory traces were collected from an impedance based RVM (ExSpiron, Respiratory Motion, Inc., Waltham, MA) in 142 non-intubated patients (age:, 19-87 yrs; BMI, 15.4-46.4 kg/m2) in the post-anesthesia care unit (PACU). Respiratory data were evaluated 30 min before & after opioid dosing. Predicted values for adequate MV (MVp) were calculated based on body surface area. “At-risk” was defined as MV <80% of MVp & “Unsafe” MV as less than 40% of MVp.
Results: 50/142 pts received opioids in the PACU. After the first dose, the group average MV decreased from 8.0L/min to 5.1L/min (-32%±3%, p<0.001). 13/19 patients classified “At-risk” had an “Unsafe” MV drop MV after opioid dosing. In contrast, only 1/31 patients classified “Not-at-risk” had an “Unsafe” MV drop (Fig 1A). With a sensitivity of 93% & a specificity of 86%, only 1 patient with potentially “Unsafe” respiratory compromise was misclassified (NPV = 97%). Individual patient response curves were plotted (Fig 1B)
Conclusions: Continuous RVM monitoring can aid in respiratory status assessment, opioid dosing & provide early warning of respiratory depression. MV trend analysis can generate patient-specific PCA settings & PRN opioid pain management regimens. Further studies to evaluate utility of this protocol are ongoing.
- © 2013 by American Heart Association, Inc.