Microcirculatory Blood Flow Is Altered During Propofol 1% Emulsion Infusion

M Koch ¹, D De Backer ², JL Vincent ², L Barvais ¹, D Hennart ¹, D Schmartz ¹

Department of Anesthesiology ¹, Department of Intensive Care ², Erasme University Hospital, Free University of Brussels, Brussels, Belgium.

Introduction:

Little is known about the microcirculatory effects of propofol in humans. Preliminary data suggests that propofol/remifentanil based TIVA anesthesia may induce marked changes in microcirculatory blood flow during cardiac surgery.¹ However, this study did not clarify what agent caused the observed effects. We hypothesized that propofol emulsion may be incriminated.

Methods:

After approval by the local research ethic committee and written informed consent, fifteen patients (35.2 ± 4.2 years, all ASA 1) undergoing transvaginal oocyte retrieval were anesthetized by sole propofol target controlled infusion (TCI) using the model of Schnider et al. (ToolBox 4.8 software).² In vivo microvideoscopy of the sublingual microcirculatory network was performed using orthogonal polarization spectral imaging. (Cytometrics, Philadelphia, PA). Five sequences of ten seconds were realized prior to induction (T1), 15 minutes after induction (T2), and 3 hours after the end of the propofol infusion (T3). Semi-quantitative analysis was done by a blinded investigator.³ Each investigated area was divided by three equidistant horizontal and three equidistant vertical lines. The vascular density was calculated as the number of vessels crossing these lines divided by the total length of the lines. Blood flow was defined as continuous, intermittent, or absent. The vessels were separated into venules and capillaries, using a diameter cut-off value of 20 µm. In each patient, the data of the five areas were averaged. Statistical analysis was done using ANOVA test for repeated measures followed by Least Significant Difference test for pair-wise post-hoc comparisons (SPSS11 software, SPSS Inc., USA). Results are expressed as mean ± SD.

Results:         

Mean propofol effect site concentration was 6.5 ± 1.8 µg/ml [4.5-10] during intraoperative assessment of the microcirculation. After induction, heart rate, mean blood pressure and Sp02 remained unchanged. (p > 0,05 T1 vs. T2) During propofol infusion microvascular density was significantly reduced. (* p < 0,05 vs. T1 ; + p < 0,05 vs. T1 and T3)

Conclusion:

During high dose TCI, propofol 1% emulsion infusion reduces microcirculatory blood flow in young, healthy humans despite normal global hemodynamic and oxygenation parameters.

References:

1 Dubois MJ et al. Intens Care Med 2002; 28 (S2) [abstract]

2 Schnider TW et al. Anesthesiology  1998;88(5):1170-82

3 De Backer D et al. Am J Respir Crit Care Med. 2002;166(1):98-104