Target-controlled infusion of propofol induction with or without plasma concentration constraint in high-risk adult patients undergoing cardiac surgery.
BACKGROUND
Calculated plasma (Cp) and calculated effect site concentrations (Ce) of propofol associated with loss of consciousness (LOC) have been studied in young healthy patients. The aim of the study was to evaluate the calculated propofol concentrations required to induce LOC in ASA III adult patients undergoing cardiac surgery using a smooth target controlled infusion of propofol.


METHODS
After informed consent, 44 patients were premedicated with 0.5 mg alprazolam orally. Propofol TCI using the pharmacokinetic set of Marsh et al. incorporated in the Diprifusor (ThalfKeo of 2.6 min) was used. Propofol Ce was progressively increased by 0.5 micro g/ml until LOC was obtained. The constraint on the maximum gradient between Cp and Ce was either 1 micro g/ml in group 1 or not limited in group 2. Hemodynamic variations were assessed.


RESULTS
Mean preoperative left ventricular ejection fractions were 44 +/- 15.4% and 56 +/- 11.4% in groups 1 and 2, respectively (P < 0.01). At LOC, mean Cp was 1.9 micro g/ml in both groups but mean Ce was 1.08 +/- 0.31 and 1.43 +/- 0.42 micro g/ml in groups 1 and 2, respectively (P < 0.01). The mean induction time was 12.8 +/- 7.1 min in group 1 and 8.5 +/- 2.7 min in group 2 (P < 0.05). No episode of hypotension has been observed in either group.


CONCLUSIONS
In ASA III patients undergoing cardiac surgery, smooth propofol TCI induction, using the pharmacokinetic set of Marsh et al. incorporated in the Diprifusor, is associated with LOC at a low mean calculated plasma concentration of 1.9 micro g/ml and good hemodynamic stability.
Hôpital Erasme, ULB, Brussels, Belgium.
V
V
Macquaire
F
F
Cantraine
D
D
Schmartz
E
E
Coussaert
L
L
Barvais
D000368:Aged; D000369:Aged, 80 and over; D018686:Anesthetics, Intravenous / Q000008:administration & dosage* / Q000493:pharmacokinetics; D001794:Blood Pressure; D006348:Cardiac Surgical Procedures; D016903:Drug Monitoring; D005260:Female; D006801:Humans; D007262:Infusions, Intravenous / Q000379:methods; D008297:Male; D008875:Middle Aged; D015742:Propofol / Q000008:administration & dosage* / Q000493:pharmacokinetics; D012307:Risk Factors; D012984:Software; D013813:Therapy, Computer-Assisted; D014474:Unconsciousness
D018686:Anesthetics, Intravenous; D015742:Propofol