title: Midazolam versus propofol for reducing contractility of fatigued canine diaphragm.
abstract: The effects of midazolam and propofol on the contractility of fatigued canine diaphragm were examined. Diaphragmatic fatigue was induced by intermittent supramaximal bilateral electrophrenic stimulation at a frequency of 20 Hz applied for 30 min. After fatigue had been induced, group I (n=10) received no study drug, group II (n=10) was given a propofol infusion (0.1 mg kg(-1) loading dose plus 1.5 mg kg(-1) h(-1) maintenance dose) and group III (n=10) was given a midazolam infusion (0.1 mg kg(-1) loading dose plus 0.1 mg kg(-1) h(-1) maintenance dose). Diaphragmatic contractility was assessed by measuring transdiaphragmatic pressure (Pdi). After the fatigue-inducing period in each group, Pdi at low-frequency (20 Hz) stimulation was lower than the baseline values (P<0.05), whereas no change in Pdi at high-frequency (100 Hz) stimulation was observed. In group II, Pdi at 20 Hz stimulation was lower than fatigued values (P<0.05); Pdi at 100 Hz stimulation did not change. In group III, Pdi at both stimulation frequencies was lower than fatigued values (P<0.05). Compared with group I, Pdi at 20 Hz stimulation was lower than fatigued values (P<0.05) during administration of the study drug in groups II and III. The decrease in Pdi was greater in group III than in group II (P<0.05). In conclusion, midazolam compared with propofol is associated with an inhibitory effect on contractility in the fatigued canine diaphragm.
authors.affiliation: Department of Anaesthesiology, University of Tsukuba Institute of Clinical Medicine, Tsukuba City, Ibaraki, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Fujii
authors.forename: H
authors.initials: H
authors.lastname: Toyooka
mesh_terms: D000759:Adjuvants, Anesthesia / Q000494:pharmacology*; D000818:Animals; D003964:Diaphragm / Q000187:drug effects* / Q000503:physiopathology; D004285:Dogs; D004558:Electric Stimulation; D008874:Midazolam / Q000494:pharmacology*; D009119:Muscle Contraction / Q000187:drug effects*; D018763:Muscle Fatigue / Q000187:drug effects*; D015742:Propofol / Q000494:pharmacology*; D014159:Transducers
chemical_list: D000759:Adjuvants, Anesthesia; D008874:Midazolam; D015742:Propofol