Pain treatment after surgery : with special reference to patient-controlled analgesia, early extubation and the use of paracetamol

Abstract

The introduction of general anaesthesia eliminated pain during surgical operations. After surgery, however, pain and postoperative nausea and vomiting (PONV) have remained a persistent problem for many patients. The need for analgesics varies widely among patients, therefore standardised treatment protocols are often insufficient pain treatment. Our studies dealt with the incidence and severity of pain and PONV after cardiac surgery. Study aims were to use and develop techniques for better evaluation of analgesic needs visual analogue scale (VAS; 0 to 10) and to develop a multimodal treatment of pain with opioids administered by the patients themselves Patient Controlled Analgesia (PCA) combined with paracetamol.

In 48 patients, PCA was compared to conventional Nurse Controlled Analgesia (NCA) on the ward after coronary artery bypass surgery. PCA led to lower VAS-scores, i.e. less pain, with the use of more opioids. In 57 patients, pain after heart surgery was compared for extubation early at 3 hours or late at 7 hours after surgery. VAS-scores, PONV and the amount of opioids used were similar whether patients were extubated early or late.

Rectal and intravenous (i.v.) administration of paracetamol was compared in 28 patients after heart surgery with respect to its bioavailability after repeated doses. Plasma concentrations after the first dose were low with rectal administration. After the fourth dose at 24 hours they reached a plateau. With i.v. administration concentrations were higher both after the first and fourth dose. Oral and i.v. paracetamol was compared in 80 patients after heart surgery and in 35 patients after day surgery (hernia repairs etc). After heart surgery the use of opioids was less in the i.v. group but VAS-scores and PONV were similar. A majority of the patients scored higher than 3 once or more than once on the 10 degree VAS-scale. In the oral group after day surgery, the plasma concentration increased in a dose-dependent manner but the scatter was wide and unpredictable as compared to the i.v. group.

Conclusions: PCA is a promising alternative to NCA for adequate pain treatment in the wards after heart surgery and is by itself adjusted to the needs of the individual patient. There is no risk that early extubation after cardiac surgery is followed by more postoperative pain. Intravenous paracetamol seems to have an opioid-sparing potential after heart surgery. Our routines must be further developed and more studies are needed to find an optimal regimen, since pain treatment sometimes was insufficient in many patients receiving the combined therapy.