July 2005 - The Hong Kong College of Anaesthesiologists

Bull HK Coll Anaesthesiol Volume 14, Number 2 July 2005Table 1. Patient demographics and operative data. Data presented as mean (SD), or number (n).Group S Ket 0.05 Ket 0.1 Ket 0.2Number of patients 12 10 15 13Age (year) 61 ± 9 67 ± 13 66 ± 12 62 ± 11Sex, M/F (n) 9 / 3 6 / 4 9 / 6 8 / 5Weight (kg) 53 ± 6 48 ± 12 54 ± 11 53 ± 11ASA Status (n)I 0 0 0 3II 12 10 15 10Type of surgery (n)Upper gastrointestinal 6 6 7 6Colorectal 6 3 8 6Gynecological 0 1 0 1Length of incision (cm) 21 ± 3.5 19 ± 3.3 19 ± 1.9 19 ± 2.3Intraoperative morphine doses (mg) 13.5 ± 4.8 10 ± 3.3 11.5 ± 3.3 12.5 ± 4.3Recovery room morphine doses (mg) 9 ± 8.6 9 ± 4 7 ± 5.8 6.5 ± 7.9Duration of surgery (min) 258 ± 80 221 ± 82 255 ± 65 254 ± 44Duration of recovery stay (min) 96 ± 36 78 ± 22 75 ± 30 69 ± 29analgesia that they had received (1 = poor, 5 =excellent).Outcome measures were compared usingthe general linear model. Complicationfrequencies were compared using χ 2 test.ResultsA total of 50 patients received the allocatedstudy medication according to protocol. Patientcharacteristics were comparable among groups(Table 1). Fifteen patients developed psychomimeticreactions (Table 2). All had vividdreams, nine out of 15 also had hallucinations(visual and/or auditory). Five of these 9 patientsdeveloped severe psychomimetic adversereactions (1 in group Ket 0.05; 2 in group Ket 0.1;2 in group Ket 0.2). They presented withparanoid delusions, disturbing visual and/orauditory hallucinations, acute agitation anddelirium. Symptoms were severe enough towarrant physical restraints, treatment withdiazepam and subsequent stopping of studydrug infusion. These adverse reactions causedsignificant compromise to the patients’ safetyand postoperative management. All 5 patientsdeveloped acute delirium during the last 12hours of study drug infusion. They sufferedfrom severe agitation, four of them pulled outthe surgical drains, all pulled out intravenouscatheters repeatedly, three required physicalrestraints and 1 attempted to leave the wardwithout success. Moreover, three patientsdeveloped paranoid delusions (2 in Ket 0.2group, 1 in Ket 0.1 group) requiring treatmentwith diazepam. All 5 patients wereasymptomatic 24 hours after stopping of studydrug infusion. On subsequent interview, all hadonly partial recollection of the events and detailsof the hallucinations. Four claimed theexperience to be stressful and frightful.However, all 5 patients reported good analgesiaduring the study period.Most of the 50 recruited patients rated theiranalgesia as good (Table 2). There were nodifferences between the groups with respect tosubjective assessment of analgesic efficacy, painscores at rest (Figure 1) and on movement(Figure 2), opioid consumption and adversereactions. We also observed a trend of smallermorphine consumption among the ketaminegroups.DiscussionIn this study, we were unable to determinethe optimal dose of subcutaneous ketamine foranalgesia in patient recovering from major85