Pj. Dawson et al., THE EFFECTS OF CARDIOPULMONARY BYPASS ON TOTAL AND UNBOUND PLASMA-CONCENTRATIONS OF PROPOFOL AND MIDAZOLAM, Journal of cardiothoracic and vascular anesthesia, 11(5), 1997, pp. 556-561
Citations number
26
Categorie Soggetti
Anesthesiology,"Peripheal Vascular Diseas","Cardiac & Cardiovascular System
Objective: To examine the effects of cardiopulmonary bypass (CPB) on t
otal and unbound plasma concentrations of propofol and midazolam when
administered by continuous infusion during cardiac surgery. Design: Pr
ospective clinical study. Setting: University hospital. Participants:
Twenty-four adult patients undergoing cardiac surgery. Interventions:
Patients received either propofol or midazolam to supplement fentanyl
anesthesia. Twelve patients received a propofol bolus (1 mg/kg) follow
ed by an infusion of 3 mg/kg/hr. A second group received midazolam, 0.
2 mg/kg bolus, followed by an infusion of 0.07 mg/kg/hr. Measurements
and Main Results: Blood samples were collected from the radial artery
cannula at 0, 2, 4, 6, 8, 10, 15, 20 minutes and then every 10 minutes
before CPB, at 1, 2, 3, 4, 6, 10, 15, 20 minutes and then each 10 min
utes during CPB. On weaning from CPB samples were collected at 0, 5, 1
0 and 20 minutes. Plasma binding, total and unbound propofol and midaz
olam concentrations were determined by ultrafiltration and high-pressu
re liquid chromatography (HPLC). CPB resulted in a fall in total propo
fol and midazolam plasma concentrations, but the unbound concentration
s remained stable. The propofol unbound fraction increased from 0.22 /- 0.06% to 0.41 +/- 0.17%. The midazolam unbound fraction increased f
rom 5.6 +/- 1.0% to 11.2 +/- 2.1%. Conclusions: Unbound concentrations
of propofol and midazolam are not affected by cardiopulmonary bypass.
Total intravenous anesthesia algorithms do not need to be changed to
achieve stable unbound plasma concentrations when initiating CPB. Copy
right (C) 1997 by W.B. Saunders Company.