Anesthesiology
-
Comparative Study
Effects of sevoflurane and isoflurane on hepatic circulation in the chronically instrumented dog.
To compare the effects of sevoflurane and isoflurane on hepatic circulation, eighteen dogs were chronically instrumented for measurements of mean aortic blood pressure and cardiac output and for simultaneous measurements of hepatic and portal blood flows. Each animal was studied while awake and during 1.2 and 2 MAC of either isoflurane or sevoflurane. Both anesthetics induced tachycardia and a dose-dependent decrease in mean aortic blood pressure (isoflurane -27% and -39%; sevoflurane -22% and -37%). ⋯ During isoflurane, the only significant change was a decrease in portal blood flow (-16%) at 1.2 MAC. Neither anesthetic significantly changed renal blood flow. Therefore, both anesthetics led to similar systemic and hepatic vasodilation.
-
Comparative Study
Prolongation of spinal anesthesia. Differential action of a lipid drug carrier on tetracaine, lidocaine, and procaine.
This study evaluates prolongation of spinal anesthesia by incorporating local anesthetics in lipid formulation. The duration and intensity of local anesthetic effect produced by different concentrations of procaine (1%, 2%, 4%), lidocaine (1%, 2%, 4%), or tetracaine (0.5%, 1%, 2%) dissolved in normal saline were compared to those produced by the same concentration of drugs in lipid (iophendylate) solution. Fifty rabbits with chronic indwelling subarachnoid catheters were divided into ten equal groups. ⋯ Our data show that iophendylate preparations of local anesthetics produce prolonged but less intense motor blockade than the aqueous solutions, except for tetracaine 0.5% in iophendylate, which produced shorter duration of motor blockade. The reduced intensity of motor blockade may be explained by decreased availability of local anesthetic at the nerve tissue due to storage of drug in the lipid depot. The increased duration of blockade signifies a sustained release of drug from the depot.
-
Randomized Controlled Trial Clinical Trial
Thiopental pharmacodynamics. II. Quantitation of clinical and electroencephalographic depth of anesthesia.
This study examined the relationship among pseudo-steady-state (constant) serum thiopental concentrations, clinical anesthetic depth as assessed by several perioperative stimuli, and the electroencephalogram (EEG). Twenty-six ASA physical status 1 or 2 patients participated in the study. Two constant serum thiopental concentrations were maintained in each patient using a computer-controlled infusion pump. ⋯ The EEG was analyzed using aperiodic waveform analysis to derive the number of waves per second. A biphasic relationship between constant serum thiopental concentration and the EEG number of waves per second was observed. Loss of responsiveness to verbal stimulation occurred when the EEG was activated at 15-18 waves/s.(ABSTRACT TRUNCATED AT 250 WORDS)