A low-dose remifentanil infusion is well tolerated for sedation in mechanically ventilated, critically-ill patients.
OBJECTIVE
To study the analgesic and sedative effects of remifentanil in critically-ill patients.


METHODS
Remifentanil infusion was started at 0.02 microg x kg(-1) x min(-1) in ten mechanically ventilated critically-ill patients, and the infusion rate was increased to 0.05, 0.10, 0.15, 0.20, and 0.25 microg x kg(-1) x min(-1) every 30 min. Basally and 25 min after each increase we measured: the Ramsey sedation score (RSS) and the respiratory response subscore of comfort scale (CSRR); the bispectral index (BIS) before and after lightly touching tracheal mucosa; heart rate and systemic arterial pressure; respiratory variables; plasma epinephrine and norepinephrine levels.


RESULTS
Infusion rates up to 0.05 microg x kg(-1) x min(-1) were effective against agitation and achieved a good degree of adaption to the respirator in all patients (RSS 2 or more and CSRR 3 or less); BIS decreased significantly; respiratory and circulatory variables were unaffected; mean plasma epinephrine levels decreased. At infusion rates higher than 0.05 microg x kg(-1) x min(-1) RSS but not BIS decreased further and patient arousability caused by noxious stimuli was not prevented; respiratory drive suppression occurred at the infusion rates higher than 0.05 microg x kg(-1) x min(-1) in four patients; bradycardia and arterial hypotension was observed in three patients; plasma epinephrine levels decreased significantly, while norepinephrine was unaffected; severe itching was experienced by one patient.


CONCLUSIONS
Low doses of remifentanil (up to 0.05 microg x kg(-1) x min(-1)) can be useful in critically-ill patients in order to achieve calm and sedation. Higher doses can inhibit respiratory drive and require controlled mechanical ventilation.
Cavaliere
Franco
F
Institute of Anaesthesia and Intensive Care, Università Cattolica del Sacro Cuore, Rome, Italy. f.cavaliere@rm.unicatt.it
Antonelli
Massimo
M
Arcangeli
Andrea
A
Conti
Giorgio
G
Costa
Roberta
R
Pennisi
Mariano Alberto
MA
Proietti
Rodolfo
R
D000368:Aged; D000369:Aged, 80 and over; D016638:Critical Illness; D004305:Dose-Response Relationship, Drug; D004837:Epinephrine / Q000097:blood; D005260:Female; D006801:Humans; D006993:Hypnotics and Sedatives / Q000494:pharmacology*; D008297:Male; D008875:Middle Aged; D010880:Piperidines / Q000494:pharmacology*; D011446:Prospective Studies; D000077208:Remifentanil; D012119:Respiration / Q000187:drug effects; D012122:Ventilators, Mechanical
D006993:Hypnotics and Sedatives; D010880:Piperidines; D000077208:Remifentanil; D004837:Epinephrine