title: Effects of hypothermia on the disposition of morphine, midazolam, fentanyl, and propofol in intensive care unit patients.
abstract: Therapeutic hypothermia (TH) may induce pharmacokinetic changes that may affect the level of sedation. We have compared the disposition of morphine, midazolam, fentanyl, and propofol in TH with normothermia in man. Fourteen patients treated with TH following cardiac arrest (33-34°C) were compared with eight matched critically ill patients (36-38°C). Continuous infusions of morphine and midazolam were stopped and replaced with infusions of fentanyl and propofol to describe elimination and start of infusion pharmacokinetics, respectively. Serial serum and urine samples were collected for 6-8 hours for validated quantification and subsequent pharmacokinetic analysis. During TH, morphine elimination half-life (t(1/2)) was significantly higher, while total clearance (CL(tot)) was significantly lower (median [semi-interquartile range (s-iqr)]): t(1/2), 266 (43) versus 168 (11) minutes, P < 0.01; CL(tot), 1201 (283) versus 1687 (200) ml/min, P < 0.01. No significant differences were seen for midazolam. CL(tot) of fentanyl and propofol was significantly lower in hypothermic patients [median (s-iqr)]: fentanyl, 726 (230) versus 1331 (678) ml/min, P < 0.05; propofol, 2046 (305) versus 2665 (223) ml/min, P < 0.05. Compared with the matched, normothermic intensive care unit patients, t(1/2) of morphine was significantly higher during TH. CL(tot) was lower during TH for morphine, fentanyl, and propofol but not for midazolam. Reducing the infusion rates of morphine, fentanyl, and propofol during TH is encouraged.
authors.affiliation: Department of Circulation and Medical Imaging, Faculty of Medicine, Norwegian University of Science and Technology, Trondheim, Norway. thor.w.bjelland@ntnu.no
authors.forename: Thor Wilhelm
authors.initials: TW
authors.lastname: Bjelland
authors.forename: Pål
authors.initials: P
authors.lastname: Klepstad
authors.forename: Bjørn Olav
authors.initials: BO
authors.lastname: Haugen
authors.forename: Turid
authors.initials: T
authors.lastname: Nilsen
authors.forename: Ola
authors.initials: O
authors.lastname: Dale
mesh_terms: D000368:Aged; D016022:Case-Control Studies; D005260:Female; D005283:Fentanyl / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D006207:Half-Life; D006323:Heart Arrest / Q000628:therapy; D006801:Humans; D007036:Hypothermia, Induced; D007362:Intensive Care Units; D057230:Limit of Detection; D008297:Male; D008874:Midazolam / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D008875:Middle Aged; D009020:Morphine / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D015742:Propofol / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D011446:Prospective Studies
chemical_list: D009020:Morphine; D008874:Midazolam; D005283:Fentanyl; D015742:Propofol