RESUMEN
Cardiac output and distribution of blood flow using 15-micron radioactively labelled microspheres were determined in 25 Wistar rats. In seven awake control animals, first and second injections of microspheres did not change cardiac output (137 +/- 8 ml/min) or result in alteration in apparent blood flow to the various organs studied. Halothane anesthesia (n = 6) (1.3 per cent inspired) resulted in a decrease in cardiac output, with increases in the percentages of cardiac output going to the brain, kidney, liver and large intestine. Enflurane anesthesia (n = 6) (2.2 per cent inspired) did not decrease cardiac output. The percentages of cardiac output going to the liver, lung, spleen, and large intestine increased. Both halothane and enflurane caused decreases in the percentages of cardiac output going to the heart and skeletal muscle. Ketamine anesthesia (n = 6) (125 mg/kg, im) differed from the other two agents in that few changes occurred from the awake state except in brain, lung and muscle, Microspheres that were trapped after the first injection were released from muscle and skin with ketamine anesthesia, resulting in an apparent decrease in the distribution of cardiac output to muscle in the controls and an apparent increase in "flow" to the lung. The microsphere method gives reliable information about cardiac output and distribution of flow in rats anesthetized with halothane or enflurane. Further studies are necessary to determine whether microsphere studies are valid indicators of organ flow during ketamine anesthesia in the rat.
Asunto(s)
Anestesia/efectos adversos , Gasto Cardíaco/efectos de los fármacos , Enflurano/farmacología , Halotano/farmacología , Ketamina/farmacología , Flujo Sanguíneo Regional/efectos de los fármacos , Animales , Presión Sanguínea , Radioisótopos de Cerio , Frecuencia Cardíaca , Masculino , Microesferas , Cintigrafía/métodos , Ratas , Radioisótopos de EstroncioRESUMEN
Although the cyanide ion-specific electrode has been used for the measurement of cyanide in biologic fluids, its validity has not been documented under these conditions. Therefore, we analyzed 60 paired samples of blood and plasma in a blinded fashion and compared the cyanide ion concentrations obtained from the ion-specific electrode with those obtained from a standard chemical assay. There was poor correlation between results in plasma samples (r = .52, n = 26) and no correlation in whole blood (r = .02, n = 34). Until refinements of the electrode technique are made, this method cannot be recommended for the measurement of cyanide in biologic fluids.
Asunto(s)
Cianuros/sangre , Electrodos , Animales , Perros , MétodosRESUMEN
A prospective study in 12 adult male patients undergoing coronary-artery revascularization was conducted to compare the effects of a morphine versus a halothane anesthetic technique on several indices of myocardial oxygen supply and demand. Indices reflecting myocardial contractility, preload, afterload, and heart rate were measured. Undesirable increases in systemic and pulmonary capillary wedge pressure were minimized using sodium nitroprusside as needed. In the period after sternotomy but before revascularization, patients anesthetized with morphine (mean 2.1 mg/kg) had significant (P less than .05) increases in rate-pressure product, tension-time index, blood pressure, and heart rate, as well as relative myocardial ischemia, evidenced by significant ST-segment depression in the V5 lead of the EKG and a decreased diastolic pressure-time index/tension-time index compared with patients anesthetized with halothane (mean .75 per cent inspired). Few difficulties associated with myocardial depression were seen in patients anesthetized with halothane. Halothane, at least in a well-monitored environment, is safe for use in patients without severe ventricular dysfunction undergoing coronary-artery revascularization.