Source: Gorgias et al. Reg Anes Pain Med 2001; 26(6): 512-7.

Reviewer:  R. Prasad, MD

Summary:

• 15 patients, 3 groups (prospective, randomized, double-blinded). No premeds.
• Double-cuff IVRA with 40ml lido 0.5% plus either:
• saline
• clonidine 1 mcg.kg
• ketamine 0.1 mg/kg
• After 10min, distal cuff up (250 mmHg), prox down. Start assessing tourniquet pain (VAS q10min), timing tourniquet duration (blinded observer)
• Groups had similar demographics, tourn durations (~95min)
• Within-group comparison. Significant diff in tourniquet pain from baseline
• lido 20min
• clonidine 40min
• ket 60min
• Between-group comparison.
• lido always highest VAS
• clon and ket similar up to 40min. 50+ min, clon higher VAS
• Tourniquet Tolerance TT = time from distal cuff inflation to first request for tourn pain relief

• No diff in sedation up to 30min after tourn release (non-signif trend for more sedation in L, prob due to higher fent doses)
• Psychomimetic effects
• 7 L-Ket pts (4 pleasant, 3 hallucinations, 3 paresthia, 2 dizzy, 1 nausea) - "in general, ... weak and were not bothersome."
• 3 L pts (2 drowsy, 1 nausea)

• No power calculation done
• Fairly high incidence of psych sx in ketamine group ... clonidine may be better choice in older patients.