16 Mohamed Naguib M~ SCH MSC, Epidural ketamine Yaw Adu-Gyamfi MB, CHS FVARCS, FWACS, Gamil H. Absood PHO, for postoperative Hesham Farag ras scH FFARCS, Henry K. Gyasi MB CHa FFARCSl analgesia Thirty-four patients of ASA physical status 1 or H Following the identification of opiate receptors in scheduled for gall bladder surgery were studied in a the spinal cord, 1 the epidural and intrathecal use comparative prospective trial to evaluate the efficacy of of opioids has increased. However, these methods epidural and intramuscular ketamine for postoperative of pain relief are not without side-effects, 2 the most pain relief. They were divided randomly into three serious of which is delayed respiratory depression.3 groups. Group I (11 patients) received 30rag intra- Ketamine [2-(O-Chlorophenyl)-2-(methylamino) muscular ketamine. Group 11 (10 patients) and Group 111 cyclohexanone HCI] is a potent analgesic. 4 Recent (13 patients) received 10 and 30rag ketamine in 1Oral studies indicate that analgesia produced by ketamine saline respectively, through epidural catheters. Pain was is mediated by opiate receptors, s'6 Since ketamine evaluated every two hours for the first 24 hours post. administered systemically is unlikely to produce operatively by using a linear analogue pain scale from respiratory depression, 7 it seemed to offer an 0-10. Ketamine was given on the patient's request and obvious advantage over the opiates. whenever the pain score exceeded three. Ketamine pro- The demonstration of the safety of intrathecal duced analgesia in all patients studied. The reduction of ketamine with preservatives in baboons by Brock- pain score after two andJbur hours in Group I and lll was Utne et al. 8 led Makowitz et al. 9 to administer significant when compared to Group H. Seven patients ketamine with preservative into the extradural space (54 per cenO in Group II1 did not require further to humans suffering from chronic pain, in an analgesia after the initial injection. However, following uncontrolled study. 10 mg epidurat ketamine or 30 mg IM ketamine, post. This paper reports a prospective randomized operative pain was more frequent. Four patients who study with two different doses of epidural ketamine received epidural ketamine complained of transient to determine the analgesic and side effects of this burning pain in the back during injection. No patient technique while employing intramuscular (IM) developed respiratory depression, psychic disturbance, ketamine as a control, in patients undergoing cardiovascular instability, bladder dysfunction or neuro- gallbladder surgery. logic deficit. It is concluded that 30 mg epidural ketamine is a safe and effective method for postoperative Methods analgesia. Thirty-four patients of ASA physical status I or II undergoing gallbladder surgery with a subcostal incision were studied. Patients with a previous history of hypertension, hyperthyroidism or psychi- attic disorders were excluded. This study was Key words approved by the institutional review committee and ANALGESICS:ketamine; ANAESTHETICTECHNIQUES: informed consent was obtained. epidural; PAIN" postoperative. Diazepam 10 mg was given orally as premedica- tion to all patients. In the operating room an From the Department of Anesthesiology, King Faisal intravenous (IV) line was established, the electro- University, King Fahd Hospital and the Department cardiograph (ECG) was monitored continuously of Biostatisties, King Faisal University (Dr. Absood). and arterial blood pressure was monitored every Address correspondence to: Dr. M. Naguib, Dept. of five minutes by an electronic oscillotonometer Anaesthesiology, King Fahd Hospital, P.O. Box (Dinamap). 2208, A1-Khobar, 31952, Saudi Arabia. A standard anaesthetic was administered to all CAN ANAESTH SOC J 1986 / 33:1 / ppl6~21 Naguib etal.: EPIDURAL KETAMINE FOR POSTOPERATIVE ANALGESIA 17 patients, This consisted of phenoperidine 2 mg, TABLE I Patientdata thiopentone 5 mg'kg -~ and succinylcholine Group I Group H Group 111 1 mg.kg -I IV. After intubation, anaesthesia was Intramuscular Epidural Epidural maintained with 70 per cent nitrous oxide in ketamine ketamine ketamine oxygen, halothane 0.5 per cent and pancuronium (30 rag) (10 rag) (30 rag) 0.1 mg-kg -l. Ventilation was controlled with a n=11 n=lO n=13 Manley Servovent to maintain normocapnia and Age (yr) end tidal CO2 was monitored by Datex infrared CO2 (mean -+ SD) 38.2-+10.6 37.2+11.2 38.6-+11.4 analyser. Sex (male/female) 4/7 3/7 4/9 Ketamine with benzethonium chloride as the Body Weight (kg) preservative was used. Patients were randomly (mean+-SD) 67.5+_11.8 62.8+-13.9 68.9+-6.0 allocated to one of three groups. Patients in Group I (control group) received 30 mg ketamine intramus- cularly (IM) for postoperative analgesia, whereas looked for and the patient's general condition was patients in Groups II and III received 10 and 30 mg observed during the trial. ketamine in 10 ml saline respectively through epi- Within 48 hours of ketamine injection, and dural catheters for postoperative pain relief. The before discharge from the hospital, all patients were epidural catheters were inserted at the end of the interviewed and a detailed neurological examina- operation using aseptic technique, at the lumbar tion was carded out and the results were recorded. vertebral level of L1-2 and advanced cephalad for 3-5 cm. Nothing was given through the catheters Statistical methods until the patients were fully recovered from the The Mann-Whitney Test was used to compare the general anaesthetic and complained of pain. medians of two independent samples. It was uti- Pain was evaluated initialy in the recovery room lized to test the difference between the groups with and then every two hours for the first 24 hours respect to the reduction in pain score after two and postoperatively by using the linear analogue pain four hours, also to test the difference between the scale from 0-10. The scale was explained to every median times until the second dose of ketamine was patient preoperatively. "Zero" corresponds to "no needed and lastly to compare the medians of the pain" and "ten" corresponds to "severe unbearable number of injections needed in 24 hours. The differ- pain." Ketamine was given on the patient's request ence was considered significant when p < 0.05. and whenever the pain score exceeded three. The Fisher's exact test was performed to test the onset and the degree of pain relief were recorded. homogeneity between groups in terms of the pro- The data were collected by one of the investigators. portion of patients who needed only one dose of Pulse, blood pressure and respiratory rate were ketamine versus those who received more than one recorded before the administration of ketamine. injection during the first 24 hours postoperatively. These observations were repeated at 5, 10, 15 and 30 minutes after ketamine administration. Hyper- tension was considered to be present if the systolic Results blood pressure increased by more than 15 mmHg Patients in each of three groups were comparable in above its previous level. Respiratory depression age, sex and body weight (Table 1). The mean pain was considered to be present if respiratory rate fell score and the total dose of ketamine administered to to eight or less per minute. Arterial blood gases each patient during 24-hour period are shown in were performed before and 30 minutes after keta- Tables II and III respectively. The time intervals mine administration in a few patients in each group (mean -+ S.D.) after the procedure at which the first at the beginning of the trial but were discontinued dose of ketamine was given to the patients were because no changes in blood gases were observed. 34.5 +-- 7.5, 36.5 -+ 11.6 and 36.1 +-- 9.8 minutes in In addition, all patients were observed for nau- Groups I, II and ILl respectively. Ketamine gave sea, vomiting, disturbed micturition, hallucination pain relief in all patients. In the first two hours, after and any other side effects. the administration of ketamine, Group HI had a Changes in sensory and motor functions were significantly greater reduction in pain score than 18 CANADIAN ANAESTHETISTS' SOCIETY JOURNAL TABLE II Meanpain score (-SD) daring first 24 hours (p < 0.01) each as compared to Group 1I. Although following operation the reduction of pain score in Group III was greater Group I Group H Group III than Group I after four hours, this difference was 134 Epidural Epidural not statistically significant (p < 0.1). ketamine ketamine ketamine Regarding the time until a second injection was (30 rag) (10 rag) (30 rag) needed, this was significantly longer in Group III Postoperative Pain score Pain score Pain score when compared with either Group I (p = 0.001) or period n=11 n=10 n=13 Group II (p < 0.001), and it was longer but not Initial pain statistically significant in Group I when compared score 6.1 - 0.9 5.9 --- 0.9 6.1 • 1.0 to Group I1. 2hours 1.8 - 0.3 2.7 +- 1.4 1.3 -+ 0.4 The number of injections needed in 24 hours in 4hours 2.7 • 1.1 3.3 • 2.6 1.8 • 1.4 Group I was greater than in Group HI (p < 0.005) 6hours 2.1 - 0.5 3.1 -+ 2.5 1.7 • 1.2 8hours 1.8 - 0.9 2.6 --- 1.4 1.4 • 1.3 but it was less than that of Group II (p < 0.05). 10hours 1.9 • 0.8 2.4 • 2.2 1.1 --- 1.1 Furthermore, the number of injections was signifi- 12hours 2.0 + 0.9 1.6 • 0.g 0.7 --+ 0.6 cantly less in Group IU than in Group II (p < 0.001). 14hours 1.7 • 0.9 2.0 -+ 1.7 0.5 • 0.8 Fisher's exact test (Table IV) showed that the 16hours 1.2 +- 0.9 1.9 +- 1.0 0.4 • 0.7 proportion of patients who needed only one dose of 18hours 1.0 --- 0.6 2.1 + 1.9 0.3 • 0.8 20hours 0.8 • 0.5 0.6 • 0.4 0.2 • 0.4 ketamine during the first 24 hours postoperatively 22hours 0.9 -+ 0.6 0.9 -+ 0.8 0.2 • 0.4 was much higher and significant in Group HI when 24hours 0.8 • 0.5 0.6 --- 0.4 0.2 • 0.4 compared with either Group I (p = 0.005) or Group II (p = 0.007), but the difference was not significant between Group I and II.