Alfentanil infusions on the intensive therapy unit

Abstract

We have investigated the use of alfentanil by infusion to sedate 14 patients during controlled ventilation on the intensive therapy unit (ITU). An initial rate of 24 micrograms.kg-1.h-1 was chosen and altered thereafter according to patient response. Incremental doses of midazolam (2.5-5.0 mg) were given intravenously (i.v.) if indicated. In 4 patients, the use of a muscle relaxant was necessary to allow adequate controlled ventilation of the patient. The mean duration of infusion was 27.9 h (range 10-141 h), and the mean total dose of alfentanil was 69.3 mg (12.5-240 mg). Spontaneous ventilation was rapidly achieved in 11 patients after stopping the infusion. The mean arterial carbon dioxide tension (PaCO2) was 5.38 kPa, 15-30 min after stopping the infusion. The clinical condition of 2 patients necessitated a change in sedation technique and one patient died during the alfentanil infusion. Alfentanil by infusion caused no major cardiovascular effects and did not influence the plasma cortisol response to trauma. There was no major alteration in blood biochemistry or haematology during the infusions of alfentanil. The plasma concentrations of alfentanil during infusion showed a wide variability. These probably relate to both changes in the volume of distribution of the drug and in hepatic clearance.

Analgesia, Sedation, and Therapeutic Paralysis in the Critically Ill

“…Absence of active metabolites results in minimal drug accumulation, however alfentanil's effects are modestly prolonged by hepatic failure. [74][75][76][77] Sufentanil is 400 to 1000 times as potent as morphine but in the ICU does not offer any significant advantages over fentanyl. Vagally mediated bradycardia and potent reductions in blood pressure are other disadvantages of this drug.…”

Alfentanil Infusions in Patients Requiring Intensive Care

“…No patient showed abnormali ties of renal or hepatic function, nor of blood haematology, coagulation or fibrinolysis, that were thought to be attributable to alfentanil (Sinclair et al 1988). No unexpected deaths attributable to alfentanil occurred but many patients died as a result of the underlying pathology.…”

“…These pharmacokinetic differences to alfentanil are reflected in the short duration of intense analgesia after alfentanil administration that allows the rapid termination of clinical effects when the infusion is stopped. The pharmacokinetics of alfentanil in intensive care patients have been investigated in 2 studies (Sinclair et al 1988;Yate et al 1986). The results from the latter are shown in table III.…”

“…In another study by Sinclair et al (1988), 14 patients requiring sedation were studied prospectively. The alfentanil infusion was started at 24 ~gf kgfh and adjusted according to clinical needs.…”