Pulmonary Kinetics of Fentanyl and Alfentanil in Surgical Patients

Abstract

Lipid-soluble basic drugs may be sequestered as the drug-loaded blood passes through the pulmonary capillaries [1], and the amount of drug remaining in the blood for distribution to the organism may be substantially reduced by this mechanism. The temporary sequestration of a significant proportion of an i.v. dose of a drug by the lung may influence the intensity and duration of its pharmacological effect [2]. Hess, Herz and Friedel [3] reported that rabbit lung had a high affinity for fentanyl: approximately 24 % of the dose administered was sequestered as the drug passed through the lung for the first time ("first pass"). Several reports demonstrated a high fentanyl binding capacity of the human lung [4-7]. This paper describes quantitatively the pulmonary kinetics of fentanyl and alfentanil in patients suffering from coronary artery disease. PATIENTS AND METHODS After approval was granted by the local ethics committee for an investigation into the pulmonary kinetics of fentanyl and alfentanil in surgical patients, informed consent was obtained from 11 patients (10 male) scheduled to undergo elective coronary artery bypass surgery. Patients ranged in age from 36 to 67 yr and in body weight from 71 to 81 kg. They were divided into two groups: fentanyl (five patients; Nos 1-5. No. 5 was the

O sistema respiratório e o idoso: implicações anestésicas

“…Entretanto, estes benefícios podem ser superados por algumas propriedades adversas destes agentes, dentre elas a supressão da vasoconstrição pulmonar hipóxica e da broncoconstrição hipocápnica 50 , além da depressão da resposta imunológica pulmonar, função já comprometida em idosos 51 . Taeger e col. relataram que uma alta percentagem de fentanil e alfentanil é seqües-trada no pulmão após administração venosa, sugerindo que o sítio de ligação pode estar localizado no surfactante alveolar 52 . Por outro lado, a ação dos opióides na musculatura lisa causa broncoconstrição 53 .…”

“…These benefits, however, may be overridden by some adverse properties of such agents, among them hypoxic pulmonary vasoconstriction and hypocapnic bronchoconstriction suppression 50 , in addition to pulmonary immune response depression, which is already affected in the elderly 51 . Taeger et al have reported that a high percentage of fentanyl is scavenged in the lungs after intravenous administration, suggesting that the binding site may be located on the alveolar surfactant 52 . On the other hand, the action of opioids on smooth muscles causes bronchoconstriction 53 .…”

Alfentanil does not increase resistance of the respiratory system in ASA I patients ventilated mechanically during general anesthesia

“…6 In spite of the great number of studies dedicated to the use of opioids during anesthesia, few data are available regarding the effects of last generation opioids on respiratory mechanics under general anesthesia. [7][8][9] A previous study has evaluated the effects on respiratory mechanics of high-dose alfentanil administration in patients undergoing cardiac surgery. 10 The aim of this study was to evaluate the effects of alfentanil administration on respiratory system mechanics in a group of ASA I patients mechanically ventilated during general anesthesia for general surgery.…”

Thiopentone pharmacokinetics during cardiopulmonary bypass with a nonpulsatile or pulsatile flow

“…Means i s.d. Lung uptake of many basic drugs has recently been demonstrated (22)(23)(24). Thiopentone is eliminated mainly by metabolism in the liver (21), but it has a low hepatic extraction ratio ( 13).…”