Target-controlled infusion of remifentanil or fentanyl during extra-corporeal shock-wave lithotripsy.
OBJECTIVE
Target-controlled infusions (TCIs) of remifentanil and fentanyl in conscious sedation regimes for extra-corporeal shock-wave lithotripsy have not been reported. We estimated the effect site concentrations of remifentanil and fentanyl needed to obtain adequate analgesia in 50% of patients (EC50) and compared both drugs in terms of intra- and post-procedure complications.


METHODS
Forty-four adult patients were randomly distributed into two groups: Group R received remifentanil and Group F received fentanyl TCI with initial effect site concentrations of 1.5 and 2 ng mL(-1), respectively. Pain was assessed using a 10-point verbal analogue scale and <3 was considered adequate analgesia. Increments or decrements of 0.5 ng mL(-1) were then introduced for subsequent patients according to Dixon's up and down method. During the rest of the procedure, TCI was adjusted to maintain verbal analogue scale <3.


RESULTS
Remifentanil and fentanyl EC50 were 2.8 ng mL(-1) (95% confidence interval (CI): 1.8-3.7 ng mL(-1)) and 2.9 ng mL(-1) (95% CI: 1.7-4.1 ng mL(-1)), respectively (n.s.). At EC50, the probability of having a respiratory rate <10 was 4% (95% CI: 0-57%) for remifentanil and 56% (95% CI: 13-92%) for fentanyl. Hypoxaemia, vomiting and sedation were more frequent in Group F during and after the procedure (P < 0.05).


CONCLUSIONS
A similar EC50 but more respiratory depression, sedation and PONV were found with fentanyl TCI than with remifentanil TCI.
Cortínez
L I
LI
Pontificia Universidad Católica de Chile, Department of Anesthesiology, Santiago, Chile. licorti@med.puc.cl
Muñoz
H R
HR
De la Fuente
R
R
Acuña
D
D
Dagnino
J A
JA
D000293:Adolescent; D000328:Adult; D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000009:adverse effects; D016292:Procedural Sedation; D016503:Drug Delivery Systems; D005260:Female; D005283:Fentanyl / Q000008:administration & dosage / Q000009:adverse effects; D006801:Humans; D000860:Hypoxia / Q000139:chemically induced; D007262:Infusions, Intravenous; D008096:Lithotripsy; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000175:diagnosis / Q000517:prevention & control; D010147:Pain Measurement; D010880:Piperidines / Q000008:administration & dosage / Q000009:adverse effects; D000077208:Remifentanil; D012129:Respiratory Function Tests; D014839:Vomiting / Q000209:etiology
D000701:Analgesics, Opioid; D010880:Piperidines; D000077208:Remifentanil; D005283:Fentanyl