Rakhman, E., Shmain, D., White, I., Ekstein, M.P., Kollender, Y., Chazan, S., . . . Weinbroum, A.A. (2011). Repeated and escalating preoperative subanesthetic doses of ketamine for postoperative pain control in patients undergoing tumor resection: A randomized, placebo-controlled, double-blind trial. Clinical Therapeutics, 33(7), 863–873.doi: 10.1016/j.clinthera.2011.05.094
To determine whether the effect of ketamine on postoperative pain can be enhanced and prolonged if ketamine is administered IM in repeated and escalating subanesthetic doses before surgery; to determine if administration of ketamine as specified can reduce consumption of analgesia
Patients were randomized to receive a placebo (saline) or ketamine.
Postoperatively, for two days, all patients received IV morphine, by means of patient-controlled analgesia (PCA), to control pain for as long as requested. PCA was initiated in the postanesthesia care unit. The PCA consisted of a bolus of 1.5 mg morphine. After a morphine dose, a patient could not access another dose for seven minutes.
Double-blind, placebo-controlled randomized controlled trial
Group K2's mean 48-hour score (P = 0.0004) and group K3's mean 48-hour score (P = 0.046) were lower than the corresponding scores of the placebo groups. Compared to the placebo groups, patients in K2 and K3 used less morphine. PCA use was approximately 50% less than PSA use in placebo-group counterparts (P < 0.05). Ketamine at 25 mg caused dizziness for two minutes.
Two or three injections of ketamine before surgery for cancer attenuated postoperative pain and decreased opioid requirements for 48 hours after surgery.
Ketamine injections before cancer surgery may attenuate postoperative pain. Ketamine can be associated with dizziness and other side effects.