Dose response study of caudal neostigmine for postoperative analgesia in paediatric patients undergoing genitourinary surgery.
BACKGROUND
Neostigmine given through the neuraxial route has been found to have analgesic properties. In this clinical trial, we evaluated for the first time the efficacy of a varying dose of caudal neostigmine for postoperative analgesia in children undergoing genitourinary surgery.


METHODS
In this double blind prospective study, we studied 120 children ASA physical status I in age group of 2-8 years scheduled for surgical repair of hypospadias under general anaesthesia. Children were randomly allocated to one of the six groups (n = 20 each) and received either no caudal block (group C) or neostigmine (groups I-V) in doses of 10, 20, 30, 40 and 50 microgram.kg-1 respectively at the end of the surgery. Postoperatively pain was assessed using an objective pain score for 24 h. Blood pressure, heart rate, SpO2, total amount of analgesic consumed and adverse effects, if any, were also recorded.


RESULTS
The duration of postoperative analgesia did not differ significantly between group C and I (P > 0.05). There was significant prolongation in the duration of analgesia in rest of the groups (group II-3.52 +/- 1.37 h; group III-6.50 +/- 1.93 h; group IV-10.45 +/- 3.41 h; group V-13.70 +/- 5.52 h) (P < 0.05). A dose dependent increase in the incidence of nausea and vomiting was also observed with highest incidence in group IV and V (group C-15%; group I-20%; group II and III-30%; group IV-45% and group V-60%) (P < 0.05). No significant alteration in vital signs and other adverse effects were noticed.


CONCLUSIONS
Caudal neostigmine in the dose range of 20-50 microgram.kg-1 provides dose dependent analgesia. However, dose exceeding 30 microgram.kg-1 is associated with a higher incidence of nausea and vomiting.
Batra
Y K
YK
Department of Anaesthesia and Intensive Care, Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh, India. ykbatra@glide.net.in
Arya
V K
VK
Mahajan
R
R
Chari
P
P
D000082:Acetaminophen / Q000008:administration & dosage / Q000627:therapeutic use; D018712:Analgesics, Non-Narcotic / Q000008:administration & dosage / Q000627:therapeutic use; D000763:Anesthesia, Caudal; D002648:Child; D002675:Child, Preschool; D002800:Cholinesterase Inhibitors / Q000008:administration & dosage* / Q000009:adverse effects / Q000627:therapeutic use*; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D006801:Humans; D007021:Hypospadias / Q000601:surgery; D008297:Male; D009388:Neostigmine / Q000008:administration & dosage* / Q000009:adverse effects / Q000627:therapeutic use*; D009407:Nerve Block; D010149:Postoperative Pain / Q000188:drug therapy* / Q000453:epidemiology; D020250:Postoperative Nausea and Vomiting / Q000453:epidemiology; D011446:Prospective Studies; D016019:Survival Analysis; D013519:Urogenital Surgical Procedures
D018712:Analgesics, Non-Narcotic; D002800:Cholinesterase Inhibitors; D000082:Acetaminophen; D009388:Neostigmine