A background infusion of morphine enhances patient-controlled analgesia after cardiac surgery.
OBJECTIVE
We compared the efficacy of patient-controlled analgesia (PCA), with or without a background infusion of morphine, on postoperative pain relief in patients extubated in the operating room after coronary artery bypass grafting (CABG) surgery.


METHODS
With Faculty Ethics approval, 60 consenting adults undergoing elective coronary artery surgery were randomly assigned to receive either morphine PCA alone (group PCA-A, n = 30) or morphine PCA plus a background infusion (group PCA-B, n = 30) for 24 hr postoperatively. Pain scores with verbal rating scale (VRS; from 0 to 10) at rest, sedation scores, morphine consumption and delivery/demand ratios were assessed at zero, one, two, four, six, 12 and 24 hr after surgery. Hemodynamic variables and arterial blood gases were also recorded in the same periods.


RESULTS
Sedation scores in the two groups were similar. At all study periods after the first postoperative hour, VRS remained below 5 in both groups. Pain scores were significantly lower in the background infusion group, which also had greater cumulative morphine consumption (61.7 +/- 10.9 mg vs 38.5 +/- 16.2 mg). There were no episodes of hypoxemia or hypertension.


CONCLUSIONS
Morphine PCA effectively controlled postoperative pain after cardiac surgery. The addition of a background infusion of morphine enhanced analgesia and increased morphine consumption.
Cukurova University, School of Medicine, Department of Anaesthesiology, 01330 Balcali, Adana, Turkey. tayguler@cu.edu.tr
Tayfun
T
Guler
Hakki
H
Unlugenc
Zehra
Z
Gundogan
Mehmet
M
Ozalevli
Okan
O
Balcioglu
Mehmet Sah
MS
Topcuoglu
D000328:Adult; D016058:Analgesia, Patient-Controlled / Q000009:adverse effects / Q000379:methods* / Q000706:statistics & numerical data; D000701:Analgesics, Opioid / Q000009:adverse effects / Q000627:therapeutic use*; D001784:Blood Gas Analysis / Q000379:methods; D016292:Procedural Sedation / Q000379:methods; D001026:Coronary Artery Bypass / Q000009:adverse effects* / Q000379:methods; D004357:Drug Synergism; D005260:Female; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D007262:Infusions, Intravenous / Q000379:methods; D008297:Male; D008875:Middle Aged; D009020:Morphine / Q000009:adverse effects / Q000627:therapeutic use*; D010147:Pain Measurement / Q000379:methods; D010149:Postoperative Pain / Q000188:drug therapy / Q000517:prevention & control; D011446:Prospective Studies; D013997:Time Factors; D016896:Treatment Outcome
D000701:Analgesics, Opioid; D009020:Morphine