ABSTRACT
During one-lung ventilation, ventilation-perfusion mismatch decreases the arterial concentration of inhaled anaesthetics due to the arterial-to-venous concentration difference. This study tested the hypothesis that in humans, the 'presumed effect-site concentration' (taken as the mid-point between the arterial and superior jugular venous concentrations) of inhaled anaesthetic falls during one-lung (vs two-lung) ventilation. Four patients scheduled for elective prostatectomy (two-lung ventilation) and four patients for elective thoracotomy (one-lung ventilation) were randomly selected and assigned to receive sevoflurane (vaporiser-dial setting, 1.5%). Sevoflurane concentrations were measured periodically from radial artery and superior jugular vein (via a catheter advanced cephalad from the jugular vein). During one-lung ventilation, the end-expiratory sevoflurane concentration was stable at â¼1.3% but the mean (SD) presumed effect-site concentration declined initially from 58 (6.7) to 43 (4.7) µg.ml(-1) (p=0.011) before slowly recovering. A period of insufficient depth of anaesthesia is thus a risk during one-lung ventilation.
Subject(s)
Anesthetics, Inhalation/blood , Methyl Ethers/blood , Respiration, Artificial , Adult , Aged , Anesthesia, General , Anesthetics, Intravenous , Dose-Response Relationship, Drug , Female , Humans , Jugular Veins , Male , Middle Aged , Piperidines , Positive-Pressure Respiration , Prospective Studies , Prostatectomy , Radial Artery , Remifentanil , Sevoflurane , ThoracotomyABSTRACT
Castrated goats were treated with dihydrotestosterone (DHT) for four weeks. Skin samples were collected from the head and the rump regions before and after the DHT treatment. The primer pheromone activities of these samples were assessed neurophysiologically by recording electrophysiological manifestations of the hypothalamic gonadotropin-releasing hormone (GnRH) pulse generator activity. Pheromone activity was detected in both the head and rump skin samples following the DHT treatment, although the development of sebaceous glands was limited to the head region. Taken together with our previous finding that testosterone treatment results in the appearance of primer pheromone activity in the skin sample of the head region but not of the rump region. these observations suggests that the regional difference of pheromone production would be ascribed to intrinsic expression levels of 5alpha-reductase, an enzyme converting testosterone to DHT.
