///2019 Abstract Details
2019 Abstract Details2019-07-13T07:45:15-05:00


Abstract Number: T1H-445
Abstract Type: Original Research

Anna-Maria Eid MD1 ; Mohamed Elgamal MD2; Mohamed Eid MD3; Antonio Gonzalez-Fiol MD4; Man Ching Cheung PhD5; Aymen Alian MD6

Introduction: Previous modalities identifying respiratory depression (RD) include pulse oximetry (SpO2), capnography (Capno) & clinical assessment, all indirect measurements – i.e. late indicators of RD. Respiratory Volume Monitoring (RVM) provides a direct quantitative measure of ventilation in non-intubated patients. This study evaluates the clinical utility of RVM vs SpO2 and Capno in identifying RD in obstetric patients.

Methods: High risk parturients scheduled for cesarean delivery receiving neuroaxial anesthesia with opioids were enrolled (ongoing). Inclusion criteria were BMI>35 kg/m2, with any following risk factors (pre-eclampsia, gestational hypertension, diabetes & OSA). MV/TV/RR were measured by RVM (ExSpiron1Xi, Respiratory Motion Inc, Watertown, MA). MV was presented as a % of predicted MV (MVPRED) based on body surface area. Low MV was defined as MV <40%MVPRED for ≥2min. Low MV resulted in an audible alarm as an indication of respiratory depression. SpO2 & Capno were measured continuously (LifeSense, Nonin Medical Inc) with defined alarm thresholds (Fig. 1). Alarm rates were compared across the three monitoring modalities.

Results: Under IRB, 16 patients (age:31±7yrs, BMI:42±7kg/m2) were monitored with RVM for 21±3 hours. 7 of these patients were also monitored with SpO2 and Capno. RVM reported metrics 90% of the time, with the remaining 10% due primarily to patient disconnection for ambulation. SpO2 and Capno reported data 70% and 6% of the time, respectively, with missing data due primarily to patient non-compliance or sensor dislodgement (Fig. 1A). RVM alarms were generally preceded by opioid administration (Fig. 1B). RVM had 1 false alarm across all patients with a false alarm rate of 0.0029 alarms/hr, significantly lower than SpO2 (2.14 false alarms/hr) or Capno (6.75 false alarms/hr) (p = 0.002, ANOVA). All 208 SpO2 alarms & 54 Capno alarms were considered false by standard criteria.

Conclusions: RVM was able to provide useful respiratory data in post-partum patients and consistent with other studies* identified opioid induced RD when other monitoring devices did not. RVM displayed an extremely low false alarm rate (0.003 false alarms/hr vs 2.17 and 6.75 for SpO2 & Capno, respectively). RVM provided earlier and more consistent data due to greater patient and staff compliance. RVM has the potential to improve patient safety without alarm fatigue or a negative impact on workflow.

*Galvagno et al. JTACS 80(5):S162-170, 2016

SOAP 2019