Intraperitoneal local anesthetics have predominant local analgesic effect: a randomized, double-blind study.
BACKGROUND
It remains unclear whether analgesia from intraperitoneal local anesthetics is via local or central mechanisms. This double-blind clinical trial tests the hypothesis that intraperitoneal local anesthetic is superior to continuous IV infusion for pain management. Primary outcome was morphine consumption during 0 to 24 h.


METHODS
Informed consent was obtained from 60 patients, age 30 to 75 yr, American Society of Anesthesiologists physical status I to II, undergoing abdominal hysterectomy. A computer-generated program randomized patients in parallel arms to group IV: continuous infusion of lidocaine 50 mg/h (10 ml) IV and saline 10 ml/h intermittently intraperitoneal; group IP: injection of lidocaine 50 mg/h (10 ml) once every hour intraperitoneally and continuous infusion of saline 10 ml/h intravenously; and group P (placebo): saline 10 ml/h both intravenously and intermittent intraperitoneal injection. Postoperative morphine consumption, pain intensity, recovery, home discharge, and lidocaine concentrations were measured.


RESULTS
Morphine consumption during 0 to 24 h was lower in group IP versus group IV, mean difference -22.6 mg (95% CI, 11.4 to 33.8; P < 0.01). No difference was seen between group IV and group P. The total mean plasma concentration of lidocaine in group IP was significantly lower than group IV, 0 to 4.5 h postoperatively (P = 0.03) with no evidence of systemic toxicity. Pain intensity and other recovery parameters were similar between the groups.


CONCLUSIONS
The lower supplemental morphine consumption and plasma lidocaine concentration in group IP would confirm that the effects of local anesthetics are likely to be predominant via local intraperitoneal receptors or anti-inflammatory effects and not via central mechanisms alone.
From the Department of Anesthesiology and Intensive Care (A.P., K.A., A.G.), and Clinical Epidemiology and Biostatistical Unit, Clinical Research Center (A.M.), Örebro University Hospital, School of Health and Medical Sciences, Örebro University, Örebro, Sweden.
Andrea
A
Perniola
Anders
A
Magnuson
Kjell
K
Axelsson
Anil
A
Gupta
D000328:Adult; D000368:Aged; D016058:Analgesia, Patient-Controlled; D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000627:therapeutic use; D000768:Anesthesia, General; D000772:Anesthesia, Local; D000779:Anesthetics, Local / Q000008:administration & dosage* / Q000097:blood / Q000494:pharmacology*; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000008:administration & dosage / Q000627:therapeutic use; D004311:Double-Blind Method; D023381:Endpoint Determination; D005260:Female; D005283:Fentanyl / Q000008:administration & dosage / Q000627:therapeutic use; D006801:Humans; D007044:Hysterectomy / Q000009:adverse effects; D007274:Injections, Intraperitoneal; D007275:Injections, Intravenous; D008012:Lidocaine / Q000008:administration & dosage / Q000097:blood / Q000494:pharmacology; D008875:Middle Aged; D009020:Morphine / Q000008:administration & dosage / Q000627:therapeutic use; D010147:Pain Measurement / Q000187:drug effects; D010149:Postoperative Pain / Q000188:drug therapy; D011446:Prospective Studies
D000701:Analgesics, Opioid; D000779:Anesthetics, Local; D000894:Anti-Inflammatory Agents, Non-Steroidal; D009020:Morphine; D008012:Lidocaine; D005283:Fentanyl