The effects of different analgesic regimens on transcutaneous CO 2 after major surgery

Abstract

Ventilatory impairment may be detected by a rise in transcutaneous carbon dioxide levels (PtcCO2). This observational study assessed the clinical utility of PtcCO2 monitoring in the postoperative period, and quantified the effect of different peri-operative analgesic regimens on postoperative respiratory function. Following pre-operative baseline PtcCO 2 recording, continuous PtcCO2 monitoring was performed in 30 patients after major colorectal surgery for up to 24 h. Mean postoperative values of PtcCO2 were 1.3 kPa (95% CI 1.0-1.5) higher than pre-operative values (p < 0.001). Patients receiving intravenous opioid patient controlled analgesia had a significantly higher elevation in postoperative PtcCO2 compared to patients receiving epidural infusion analgesia, 1.8 kPa (CI 1.5-2.1) vs 0.7 kPa (CI 0.5-0.9) respectively (p < 0.001). The mean rise in PtcCO2 following a single intravenous bolus of morphine delivered via PCA was 0.05 kPa (SEm 0.01), peaking at 12 min post-dose. The transcutaneous capnometer successfully recorded data for 98% of the total time it was applied to patients. © 2008 The Authors.