UICC World Cancer Congress 2006

Objective:Opioid induced respiratory depression is the most feared opioid side effect by physicians and patients yet research is scant in regards to this side effect in cancer patients. We evaluated the change in respiratory parameters during parenteral opioid titration for cancer pain in order to determine if opioid titration is associated with hypoventilation. The primary objective of this study was to measure the changes in ET-CO2 from initiation of opioid titration to pain control.

Methods:Subjects with severe cancer pain admitted for parenteral opioid titration for poorly controlled pain were eligible. Those who were oxygen dependent were excluded. End-tidal CO2 (ET-CO2), O2 saturation, respiratory rate (RR), and vital signs were monitored daily using a capnometer until pain control. Analysis was done using a paired t-test to compared ET-CO2 pre and post titration

Results:30 patients completed the study. The mean ET-CO2 at initial evaluation was 33.3 ± 5.0 mm Hg and 34.7 ± 5.7mm Hg at the time of pain control (P=0.14, 95% CI -0.5 to 3.3). None had an ET-CO2 °Ý 50 mmHg. All maintained O2 saturation °Ý 92%. RR transiently dropped in two subjects to below 10. Parenteral opioid titration for relief of cancer pain is not associated with significant or clinical respiratory depression as demonstrated by significant changes in ET-CO2 or hypoxemia in non-oxygen dependent cancer patients.