Plasma thromboxane B2 levels and thromboxane B2 production by platelets are increased in patients during spinal and epidural anesthesia.

Concentrations of thromboxane (Tx) B2 in plasma and its production by platelets were measured in 20 spinal and 10 epidural anesthesia patients scheduled for small operations in the lower extremities. The main metabolite of prostacyclin, 6-keto-PGF1 alpha and prostaglandin (PG) E2 in plasma were also determined. Plasma TxB2 and TxB2 production by platelets increased during both spinal and epidural anesthesia. Plasma TxB2 levels also remained elevated 1 h after anesthesia. The plasma concentrations of 6-keto-PGF1 alpha and PGE2 did not change during spinal or epidural anesthesia. In in vitro studies, only low concentrations of lidocaine (0.5-1.0 micrograms/ml) and bupivacaine (0.5-3.0 micrograms/ml) increased platelet TxB2 production. In platelet rich plasma, neither lidocaine nor bupivacaine in concentrations of 0.5-3.0 micrograms/ml caused constant changes in ADP-induced platelet aggregation, but they inhibited it in toxic concentrations (12 micrograms/ml). The results suggest that the increased TxB2 plasma levels and platelet TxB2 production during regional anesthesia are not caused by local anesthetics itself but by other factors, e.g. tissue trauma. In clinically found concentrations, local anesthetics do not cause any constant changes in platelet aggregation.

Predicting the prognosis with trauma indices in surgical patients treated in the intensive care unit.

Trauma indices, acute trauma, CHOP (Creatinine, Haematocrit, Osmolality, Pressure), respiratory and renal indices, based on routinely used biochemical and physiological data, are mathematical quantities which have been developed for predicting the outcome of critically ill patients. We evaluated the use of these indices in 212 surgical intensive care patients. By fitting the index value, the age and sex of the patient to a logistic model, the probability of death (PD) was obtained. Poorest values of various indices and highest PD values were observed in postoperative abdominal surgery patients both on admission and during intensive care. Lower PD values were found in multiple trauma and brain injury patients. The outcome of a patient can be predicted already by means of the admission values. These indices are feasible since they require only easily available data. Before use, their validity must be checked at the hospital concerned.

Biochemical indicators of myocardial ischaemia during coronary artery bypass grafting.

Metabolic indicators of myocardial ischaemia were measured in coronary sinus blood in six patients undergoing coronary artery bypass grafting (CABG). Five arterial and coronary sinus blood samples were taken in each case--one before cardiopulmonary bypass (CPB), and three during and one after CPB. Moderate hypothermia with topical cardiac cooling and cold cardioplegia were used. Myocardial infarction occurred perioperatively in two patients. Myocardial lactate production was not found before CPB in any patient, but it was common during CPB. Adenosine, inosine and hypoxanthine were released into the coronary sinus blood, but their release did not correlate significantly with lactate production. Myocardial noradrenaline production showed positive correlation with lactate levels (p less than 0.05). Release of adrenaline from the myocardium during CABG was also demonstrated. Myocardial catecholamine production was especially seen in the patients with myocardial infarction. Myocardial catecholamine release seemed to be the most sensitive of the studied biochemical indicators of myocardial ischaemia during CABG.

Effects of halothane and enflurane on prostanoid concentrations in operation patients.

Prostanoid formation may be stimulated by different events associated with anaesthesia and operation, such as positive pressure ventilation and tissue trauma. We investigated the effects of halothane and enflurane on plasma and serum prostanoid concentrations in 19 patients scheduled for minor operations. In 9 abdominal surgery patients, thromboxane B2 concentrations were followed up to the fifth postoperative day. Prostanoid determinations were carried out with RIA. In general, the changes in prostanoid concentrations in patients anaesthetised with halothane or enflurane were similar. During spontaneous breathing there was a decrease in plasma PGE2 and TxB2 concentrations. During intermittent positive pressure ventilation and operation, PGE2 and TxB2 concentrations rose but 6-keto-PGF1 alpha did not. After operation, TxB2 concentrations remained elevated but the other prostanoids returned to preoperative values. TxB2 concentrations decreased to the preoperative level on the first postoperative day. The elevated TxB2 concentrations during and after surgery can be regarded, in some patients, as a potential risk factor for cardiovascular and thromboembolic complications.