Growth of allogeneic sarcoma in mice subjected to halothane anesthesia and/or surgical stress.

The present study was designed to clarify mechanisms involved in suppression of cell-mediated immunity reported in patients undergoing major surgery with general anesthesia by determining the effects of halothane anesthesia with and without surgery on the growth of Sarcoma I (Sa I), a tumor allogeneic to BALB/c mice. Mice were given subcutaneous injections of 5 X 10(6) tumor cells from A/Jax mice and then immediately exposed to 0.5%-1.0% halothane for 1 hr without surgery (n = 7) or with surgery (midline laparotomy; n = 12). In control groups mice were also injected with tumor cells but were not exposed to prolonged halothane anesthesia. Some of them received only Sa I (n = 6), while the rest (n = 7) were also laparotomized. The rejection time of Sa I in mice exposed to halothane anesthesia was significantly longer (15.4 +/- 1.25 days) than in untreated controls (12.0 +/- 0.68 days) (P less than 0.05). In the mice exposed to halothane tumor growth was also greater. Surgical stress per se did not significantly affect growth or rejection time of Sa I (11.0 +/- 0.66 vs 12.0 +/- 0.68 days). Similarly, the combination of surgical stress with halothane anesthesia did not affect the immunosuppression associated with halothane alone (12.9 +/- 1.3 vs 15.4 +/- 1.25; P less than 0.05). The results indicate that halothane anesthesia per se may be associated with impairment of cell-mediated immunity under experimental conditions.

Quantitative analysis of trifluoroacetate in the urine and blood by isotachophoresis.

Trifluoroacetate (TFA), the major metabolite of halothane, was assayed by a newly developed isotachophoretic technique. This technique has several advantages over the presently used methods of analysis. It requires no special preparation of urine or blood samples. The sample volume is small (5--100 microliters) and the analysis time is short (30--90 min per sample). In addition, the method provides an analysis that is both qualitative and quantitative over a wide range of concentrations (from 2 nanomoles in 200 microliters to 200 nanomoles in 5 microliters). In this study, the assay was performed using HCl (0.001 M) in 1 per cent Triton X-100, titrated with beta-alanine to a pH value of 3.6--3.9 as the leading electrolyte and n-caproic acid (0.01 M) as the terminal electrolyte (50--100 muA migration current). Using this technique, daily urinary TFA excretion of seven patients was measured during halothane anesthesia and for 14 days postoperatively. The TFA values were highest on the second postoperative day (317--1,259 mg). The mean values of the urinary TFA excreted during the entire study (2,501 +/- 493 mg, mean +/- SEM) were much higher than those reported previously. The isotachophoretic technique provides a sensitive assay for future research into the biotransformation of halothane.