Table 6. Incidence of Side Effects and Pain Requiring an Early Discontinuation of the Patient-controlled Analgesia Combination

In no patient the combination was discontinued because of respiratory depression. Combinations E and K were re-analyzed in 6 patients because of retesting (see Methods, Optimization Procedure). Data are expressed as the number of patients in which the combination was discontinued. In brackets, the time from the beginning of the study to discontinuation of the patient-controlled analgesia combination because of side effects or pain is reported (h). See table 2for a description of the criteria for discontinuing the therapy.

Ke = concentration of ketamine in the patient-controlled analgesia solution (mg/ml); Lo = lockout interval (min); Mo = concentration of Morphine in the patient-controlled analgesia solution (mg/ml).