Anesthesia and analgesia
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Anesthesia and analgesia · Oct 1991
Treatment of acute systemic toxicity after the rapid intravenous injection of ropivacaine and bupivacaine in the conscious dog.
Two groups of six beagle dogs received rapid intravenous (IV) injections of ropivacaine or bupivacaine on two occasions in a blinded random fashion. Initially, a dose sufficient to cause convulsions (CD) was given followed by twice the CD (2 x CD), which was administered 48 h later. The CD of bupivacaine (4.3 mg/kg) and ropivacaine (4.9 mg/kg) caused significant (P less than 0.05) increases in heart rate and mean arterial blood pressure. ⋯ Another dog had two 1-s bursts of premature ventricular contractions requiring no treatment. The rapid treatment of convulsions and cardiovascular toxicity resulted in a decreased number of deaths in both groups when compared with dogs from a previously published study in which no therapy was instituted. Thus, early aggressive treatment of central nervous system and cardiovascular system toxicity is capable of reducing the incidence of mortality associated with the rapid intravenous administration of excessive doses of local anesthetics.
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Anesthesia and analgesia · Oct 1991
Comparative StudySimultaneous cardiac output measurements by transtracheal Doppler, electromagnetic flow meter, and thermodilution during various hemodynamic states in pigs.
The transtracheal Doppler (TTD) method of cardiac output (CO) measurement was compared with thermodilution (TDL) and aortic electromagnetic flow meter (EFM). Simultaneous CO measurements with the three methods were obtained during various hemodynamic states in eight pigs. Cardiac output ranged from 1 to 3 L/min during the study. ⋯ Regression analysis yielded TTD = 0.383 + 0.779 TDL (r = 0.86); TTD = 0.351 + 0.788 EFM (r = 0.87); TDL = 0.077 + 0.95 EFM (r = 0.95). Only a change greater than 0.6 L/min in TTD CO could predict with 95% confidence a change in TDL or EFM CO. These results suggest that, in the CO range of this study, the TTD method does not accurately reproduce the CO measurements obtained by TDL or EFM.
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Anesthesia and analgesia · Oct 1991
Adverse interaction between bupivacaine and halothane on ventricular contractile force and intraventricular conduction in the dog.
Regional anesthesia with bupivacaine in pediatric patients is often accompanied by light levels of halothane general anesthesia. To determine the potential cardiotoxicity of these two drugs when used together, we defined the interaction between moderate plasma bupivacaine concentrations (1270-1760 ng/mL) and halothane (end-tidal concentrations, 0.5%-1.0%) on ventricular contractility and conduction in 22 closed-chest dogs anesthetized with chloralose. ⋯ In other dogs given halothane but in which bupivacaine levels were held constant (1400 ng/mL), VCT remained constant and VERP lengthened slightly, whereas dP/dtmax decreased. We conclude that the combination of bupivacaine and halothane can cause adverse effects on ventricular contractility and intraventricular conduction.
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Several commercially available catheters are currently marketed for continuous intrathecal use. Initial studies using continuous spinal catheters have reported several occurrences of retained fragments after removal of the catheter. Accordingly, we measured the break strength of five commercially available catheters. ⋯ We also tested a commonly used Burron 20-gauge catheter, which is marketed for epidural use, and found it had an average break strength of 6.35 lb. The tested values obtained for the TFX/Rusch catheters were lower than the break strength values supplied by the manufacturers. The authors conclude that the break strength of spinal catheters is one-third to one-half that found for a typical epidural catheter.