Dual effect of thiopentone on human granulocyte activation. Non-intervention by ketamine and morphine

The inhibitory effects of thiopental, midazolam, and ketamine on human neutrophil functions

We investigated the effect of thiopental, midazolam, and ketamine (at clinically relevant concentrations and at 0.1 and 10 times these concentrations) on several aspects of human neutrophil functions. The three intravenous (i.v.) anesthetics significantly decreased chemotaxis, phagocytosis, and reactive oxygen species (ROS) (O2-, H2O2, OH) production of neutrophils in a dose-dependent manner. At clinically relevant concentrations, thiopental and midazolam significantly depressed these neutrophil functions. However, ketamine at the clinical plasma concentration did not impair chemotaxis or ROS production, except phagocytosis. In contrast, the three anesthetics had no effect on the levels of ROS production by a cell-free ROS generating system. In addition, intracellular calcium concentrations in neutrophils stimulated by N-formyl-L-methionyl-L-leucil-L-phenylalanine were dose-dependently decreased in the presence of each of the three anesthetics. The suppression of an increase in intracellular calcium concentrations may be responsible for the inhibition of neutrophil functions by the i.v. anesthetics.

IMPLICATIONS

Neutrophils play an important role in the antibacterial host defense system and autotissue injury. We found that thiopental and midazolam (but not ketamine), at clinically relevant concentrations, impaired the neutrophil functions.

Effect of anaesthetic agents on the phagocytic function of human polymorphonuclear leukocytes through analysis with a phagocytic plaque method

We examined the effects of the intravenous anaesthetic agents, thiamylal and ketamine, on the phagocytic function of polymorphonuclear leukocytes (PMN) in heparinized peripheral blood from healthy individuals using the phagocytic plaque method. Subclinical doses of thiamylal caused enhancement of the phagocytic activity of PMN and super-clinical doses of thiamylal inhibited phagocytic activity of PMN. Ketamine did not adversely affect phagocytic function at relevant therapeutic concentrations. The results presented in this manuscript indicate the phagocytic plaque method can provide a quantitative assessment of the phagocytic function of leukocytes. This method may prove useful in determining whether anaesthetic agents and other drugs adversely affect leukocyte function and hence help prevent the increased susceptibility to infection which can occur in anaesthetized patients. Conversely, the phagocytic plaque method may prove useful in the search for immune-enhancing drugs.

Stereoselective suppression of neutrophil function by ketamine?

The effects of the commercially available ketamine preparation (Ketanest), the ketamine racemate and of the two enantiomers, the R(-)-racemate and the S(+)-racemate, as well as its drug-free solvent were examined by N-formyl-methionyl-leucyl-phenylalanine-(FMLP)- and zymosan-induced oxygen radical production of polymorphonuclear cells (PMN). The racemate and the two enantiomers of ketamine suppressed FMLP- and zymosan-induced chemiluminescence of PMN in a dose-dependent fashion to the same extent. Therefore suppression of chemiluminescence of PMN by ketamine does not result from a specific receptor interaction.

Effects of propofol and thiopentone on polymorphonuclear leukocyte functions in vitro

Anesthetic agents may impair host defense mechanisms including polymorphonuclear leukocyte (PMNL) function. We have studied the effects of thiopentone and propofol in low (thiopentone 10 mg/L, propofol 2 mg/l) and high (thiopentone 40 mg/L, propofol 6 mg/L) clinically relevant concentrations on PMNL adherence, chemotaxis, phagocytosis and killing in vitro. The results demonstrated that thiopentone in both concentrations significantly decreases all PMNL functions tested and had a direct influence on the PMNLs in terms of their chemotactic response. In contrast, propofol decreases significantly only PMNL chemotaxis but not adherence, phagocytosis and killing. The effect of propofol was not attributable to the lipid carrier vehicle, as Intralipid with same formulation had no effect on PMNL function. We conclude that propofol is a relatively safe agent from the viewpoint of PMNL function in vitro, which may be of potential clinical benefit.

Do anaesthetics and surgical stress increase the risk of post-exposure rabies treatment failure?

Rabies is fatal in humans and, after exposure, only correct postexposure treatment as outlined in World Health Organization guidelines can prevent the disease. Analysis of case reports of treatment failures has shown that recommendations have not been followed and that patients presenting risk factors should receive additional care. Known risk factors are delay of more than 24 h in starting postexposure treatment, multiple wounds (especially on head, neck, arm or fingers), incorrect initial wound treatment, immunodepression and non-application of anti-rabies immunoglobulins or serum. We present a case, recently reported from India to Drug Surveillance Behringwerke AG, Marburg, Germany, in which surgery under ketamine anaesthesia might have been an additional risk factor for postexposure treatment failure.

Effects of anaesthesia and surgery on the immune response

Alterations have been found to occur in every component of immune response during anaesthesia and surgery. These alterations represent the body's general physiological responses and are mainly dependent on the extent of surgery, as well as other factors such as the patient's age and health status, medication and blood transfusion. Anaesthetic and operative complications have profound effects on these responses. Basically, the immune response to anaesthesia and surgery is a beneficial reaction, needed in local host defences and wound healing and in preventing the body from making autoantibodies against its own tissues. The responses may, however, contribute to the development of postoperative infections and spread of malignant disease. During uncomplicated conventional surgery, the immune response usually passes clinically unnoticed without any harmful effects. Absent responses and excessively high responses, on the other hand, harm the patient. Our understanding of immunological phenomena and our possibilities of controlling mediator activation are now lagging behind the technical advances made in operative treatment. If we want to decrease operative morbidity and mortality to below their present levels, more attention should be directed to immune responses to major surgery, injuries and operative complications with massive mediator release which place the surgical patient at risk. Experimental evidence suggests that results of treatment in injured and operated patients can in the future be improved by controlling immune responses and their mediator systems. Our current level of knowledge of immune responses is already helping us to avoid many immune-mediated complications. However, routine interference with these responses is not indicated.

Effects of thiopental on granulocyte oxidative microbicidal capacity

Some anaesthetics are known to depress granulocyte chemiluminescence responses in the phagocytosis of zymosan as a measure of their oxidative microbicidal capacity. In this study the effects of thiopental were measured on chemiluminescence responses in the phagocytosis of Staphylococcus aureus and Escherichia coli, which are the commonest bacteria causing postoperative infections. Granulocytes from 14 healthy volunteers (mean age 35 +/- 9 (s.d.) years) were tested in vitro in the presence of clinical thiopental concentrations 0, 5, 10 and 25 micrograms/ml (0, 18, 36 and 91 mumol/l, respectively). During a 60-min exposure period, decreased chemiluminescence responses occurred to Staph. aureus at 5 micrograms/ml (P less than 0.01) and higher thiopental concentrations and to E. coli at 10 micrograms/ml (P less than 0.01) and higher concentrations, as a sign of depressed oxidative microbicidal activity.