Anesthesia and analgesia
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Transient maternal hypotension following regional anesthesia can lead to significantly lower umbilical cord pH values. Although this acidosis has not been found to be clinically significant, acidosis may increase the placental transfer of local anesthetic agents as a result of "ion trapping." The purpose of this study was to examine the pharmacologic and clinical consequences of transient maternal hypotension following epidural anesthesia with 0.5% bupivacaine before cesarean section. ⋯ The pH of umbilical cord venous and arterial blood and the concentration of bupivacaine were significantly lower (P less than 0.05) in neonates of mothers in the hypotensive group than in neonates of mothers that did not develop hypotension. The results show, however, that transient maternal hypotension following epidural anesthesia does not lead to a greater placental transfer of bupivacaine due to "ion trapping" even though neonatal cord blood pH decreases.
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Anesthesia and analgesia · Nov 1989
Randomized Controlled Trial Clinical TrialAcute toxicity of ropivacaine compared with that of bupivacaine.
The acute central nervous and cardiovascular effects of the local anesthetics ropivacaine and bupivacaine were compared in 12 volunteers in a randomized double-blind manner with use of intravenous infusions at a rate of 10 mg/min up to a maximal dose of 150 mg. The volunteers were all healthy men. They were familiarized with the central nervous system (CNS) toxic effects of local anesthetics by receiving a preliminary intravenous injection of lidocaine. ⋯ Stroke volume and ejection fraction were reduced. There was no change in cardiac output. Although both drugs caused evidence of depression of conductivity and contractility, these appeared at lower dosage and lower plasma concentrations with bupivacaine than with ropivacaine.(ABSTRACT TRUNCATED AT 250 WORDS)
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Anesthesia and analgesia · Nov 1989
Comparative StudyA comparative study of methods of detection of esophageal intubation.
The trachea and esophagus of 21 patients were simultaneously intubated to comparatively evaluate methods for detecting esophageal intubation. In succession, the trachea and esophagus were ventilated with the same inspiratory volume of 621 +/- 45 mL (mean +/- SD). Carbon dioxide (CO2) levels, volumes, and temperatures of expired gas were measured from the tracheal and esophageal tubes. ⋯ Peak temperatures of expired gas recorded from the tracheal tube (32.0 +/- 0.73 degrees C) were higher than those from the esophageal tube (27.3 +/- 1.2 degrees C) (P less than 0.001). The shape of temperature waveforms with a correctly placed tracheal tube remained constant with each ventilation, contrary to that obtained from an esophageal tube. Although the occasional detected of CO2 waveforms from an esophageal tube might lead to an incorrect assessment of tube placement, this limitation of CO2 analyzer can be offset by measurement of volume and temperature of expired gas in identifying placement of an endotracheal tube.
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Anesthesia and analgesia · Nov 1989
Comparative StudyBronchial cuff pressures of double-lumen tubes.
Pressure damage to respiratory mucosa from overinflation of bronchial cuffs has been implicated as a cause of bronchial rupture, a rare but devastating complication of double-lumen endobronchial tubes (DLTs). We compared the pressure/volume characteristics of the bronchial cuffs of three different polyvinylchloride (PVC) DLTs and an equivalent sized red-rubber Robertshaw DLT. At the volume needed to seal effectively our bronchial model, two of the three PVC tube cuffs tested generated significantly less pressure than did that of the cuffs of the third PVC and the red-rubber Robertshaw tubes.