Influence of Pentobarbital, Propofol and Ketamine on Skeletal Muscle Capillary Perf usion during Hemorrhage: A Comparative Study in the Rabbit

Abstract

Anesthetics affect tissue blood flow, which is of importance especially in situations of inadequate perfusion, as in hemorrhage. The present study compared the effect of three commonly used anesthetic agents on skeletal muscle capillary and regional blood flow during and after recovery from hemorrhage. Three groups of rabbits were anesthetized randomly with either pentobarbital, propofol or ketamine, chosen such that the anesthetic level, blood pressure and withdrawn blood volume were comparable in all groups. Capillary blood flow was measured using a local hydrogen clearance technique with a multiwire microelectrode, placed on the left vastus medialis muscle surface, and the contralateral site served for regional microcirculatory blood flow measurements using laser-Doppler flowmetry. Hemorrhage was induced by withdrawal of blood to a mean arterial pressure of 40 mm Hg and monitoring was continued during the subsequent spontaneous recovery period of 120 min. Both capillary and regional blood flow decreased significantly during hemorrhage in all groups. The flow values in the pentobarbital group were given a mean value of 100% and the other two groups were compared with this. Local hydrogen clearance flow decreased from a relative baseline level of 100 to 64% during hemorrhage with pentobarbital, from 87 to 43% with propofol and from 146 to 70% with ketamine. Laser-Doppler flowmetry flow decreased from relative baseline levels of 100, 96 and 139%, to 71, 77 and 103%, respectively, during hemorrhage, whereas the percentage of zero capillary flow values increased from 4 to 34, 19 to 50 and 5 to 27% in the three groups, respectively. The results of the present study indicate that capillary perfusion is best maintained in the ketamine group followed by pentobarbital and propofol last. Furthermore, the flow distribution shapes for each anesthetic indicate a more pronounced deregulation of capillary blood flow in the propofol group than in the others, even at baseline.

Differential effects of intravenous anaesthetic agents on the response of rat mesenteric microcirculation in vivo after haemorrhage

“…26 These observations are in agreement with previous studies in skeletal muscle, demonstrating well-maintained capillary perfusion with ketamine anaesthesia. 28 Constriction of arterioles and venules may have also maintained hydrostatic pressure and prevented¯uid loss into the mesenteric extravascular space and hence, the abdomen. Interestingly, after haemorrhage¯uid absorption appeared to be greater during ketamine anaesthesia, 29 as indicated in the present study by the greater decrease in haematocrit.…”

A literature review: The effects of magnetic field exposure on blood flow and blood vessels in the microvasculature

“…Another commonly used anesthetic is propofol. In an experiment by Gustafsson et al [1995], the effects of three popular anesthetics on skeletal muscle capillary and regional blood flow were compared. This study indicated that ketamine maintained capillary perfusion the best, followed by pentobarbital and then propofol.…”

Acid-base disturbance during hemorrhage in rats: significant role of strong inorganic ions

“…In the present study, only the anesthetized groups showed low pH values and higher plasma [K ϩ ]. Finally, the absence of significant differences in MAP between anesthetized groups suggests that ketamine could prevent the development of tissue hypoxia during hemorrhage by affecting peripheral cardiovascular mechanisms rather than central cardiovascular control (14,26). A better peripheral vascular condition in KA rats would be reflected in the present study as an acid-base behavior intermediate between C and UA rats.…”

“…Several studies have addressed questions on the peripheral circulatory actions of anesthetics during hemorrhage, but there is little specific information about their acid-base effects during hemorrhagic shock in rats. Ketamine is widely used in studies on hemorrhage in several species (14,15,26,36), whereas urethan has been used to a lesser extent (33). An additional goal of the present study was to compare the evolution of acid-base changes during hemorrhage in rats anesthetized with ketamine or urethan with respect to that found in conscious hemorrhaged rats.…”

“…Another frequent finding during hemorrhage is that anesthetic agents are often associated with a significant deterioration in microvascular control mechanisms, which leads to a reduction in the O 2 extraction capacity of tissues (14,33,35). Several studies have addressed questions on the peripheral circulatory actions of anesthetics during hemorrhage, but there is little specific information about their acid-base effects during hemorrhagic shock in rats.…”