///2015 Abstract Details
2015 Abstract Details2019-08-02T16:54:43-06:00

Pulse oximetry is the least effective monitoring modality to detect respiratory depression among laboring women receiving remifentanil

Abstract Number: T-14
Abstract Type: Original Research

Carolyn F Weiniger MB ChB1 ; Brendan Carvalho MBBS2; Daniel Stocki MD3; Sharon Einav MD4

Introduction: Intravenous opioids may cause respiratory depression (RD); apnea leading to respiratory arrest has been reported with remifentanil used for labor analgesia (1). While frequent unnecessary alerts may lead to alarm fatigue, insufficient sensitivity increases the risk of undetected events. We aimed to identify a reliable monitor to detect RD in women receiving remifentanil during labor.

Methods: Secondary analysis of a prospective IRB-approved study of healthy women receiving intravenous patient-controlled boluses of remifentanil 20-60 mcg q1-2 mins for labor analgesia. Women were monitored continuously with respiratory rate (RR), end-tidal CO2 (EtCO2), pulse oximetry (SpO2), heart rate (HR), and the Integrated Pulmonary Index (IPI) (Capnostream©; Covidien, Boulder CO). The IPI value (1-10; 10 =healthy patient, =<4 =immediate attention required, 1 =dire condition), is generated from a logic algorithm using the RR, EtCO2, SpO2 and HR parameters. Alarm triggers included: RR <8 breaths per minute (bpm), EtCO2 <15 mmHg, and SpO2 <92% for at least 15 sec. Apnea was defined as EtCO2 <5 mmHg for at least 30 consecutive seconds.

Results: Nineteen laboring women, aged 31±5 yrs and BMI 26±3 were randomized to receive remifentanil (total dose 1725±1392 mcg, administered over 160±132 min). There were 331 cumulative individual parameter alerts; RR <8 bpm, EtCO2 <15 mmHg, SpO2 <92%, with 82% of these alerts lasting => 10 secs. There were 190 IPI alerts =<4, with 84% of these IPI alerts lasting =>10 secs. In total, 62 apneas were counted; 100% were detected by the IPI =<4 alert, 100% by RR <8 bpm, 76% by EtCO2 <15 mmHg, and 15% by SpO2 <92%. In 47/62 (76%) apnea events, IPI, RR and ETCO2 alerts were all triggered, Figure.

Conclusion: SpO2 - often viewed as the superior monitor for RD, exhibited the worst performance in detecting apnea. RR and IPI alarms were more sensitive than EtCO2 and SpO2 for detection of RD during intravenous remifentanil boluses for labor analgesia. Most of the alerts not captured by the IPI were of short duration,and of no clinical consequence.

1. Bonner JC. Anaesthesia 2012;67:538-40

SOAP 2015