Anesthesiology
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Comparative Study
The minimum alveolar concentration (MAC) and hemodynamic effects of halothane, isoflurane, and sevoflurane in newborn swine.
To determine the minimum alveolar concentration (MAC) and hemodynamic responses to halothane, isoflurane, and sevoflurane in newborn swine, 36 fasting swine 4-10 days of age were anesthetized with one of the three volatile anesthetics in 100% oxygen. MAC was determined for each swine. Carotid artery and internal jugular catheters were inserted and each swine was allowed to recover for 48 h. ⋯ Compared to awake SAP, mean SAP measurements decreased 46% at 1.5 MAC halothane (P less than 0.001), 43% at 1.5 MAC isoflurane (P less than 0.001), and 36% at 1.5 MAC sevoflurane (P less than 0.005). Mean SAP at 1.0 and 1.5 MAC halothane and isoflurane were significantly less than those measured at equipotent concentrations of sevoflurane (P less than 0.005). Compared to awake CI, mean CI measurements decreased 53% at 1.5 MAC halothane (P less than 0.001) and 43% at 1.5 MAC isoflurane (P less than 0.005).(ABSTRACT TRUNCATED AT 250 WORDS)
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The authors performed a clinical trial in 313 patients in labor to determine the safety and efficacy of an air test for unintentional intravenous placement of epidural catheters. Following routine aspiration for blood and cerebrospinal fluid, 1 ml of air was injected through each epidural catheter while heart tones were continually monitored with a Doppler ultrasound probe placed over the maternal precordium. In 281 patients, Doppler heart tones did not change following air injection (negative air test). ⋯ In six cases, adequate levels of analgesia developed despite a positive air test (false-positive rate, 2%; 95% confidence limit, 0.7-4.3%). None of the 303 patients receiving the air test developed any complications attributable to the injection of air (95% confidence limits, 0.0-1.0%). The authors conclude that air, with precordial Doppler detection, is a safe and effective test for identifying intravenously located epidural catheters.
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Randomized Controlled Trial Clinical Trial
Use of a chlorhexidine dressing to reduce microbial colonization of epidural catheters.
We performed a prospective randomized controlled trial to assess the efficacy of a chlorhexidine dressing in reducing the microbial flora at the insertion site of epidural catheters. These catheters were used for acute pain management and were dressed either by a standardized method or with a CHX/urethane sponge composite. ⋯ The CHX dressing caused no adverse effects. The data suggest that delivery of antiseptic to the catheter wound site reduces catheter colonization with a possible reduction in the risk of epidural catheter-related infection.
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Hormonal and metabolic responses were measured in 15 neonates who underwent repair of complex congenital heart defects during a standardized anesthetic protocol. Four of the 15 neonates died postoperatively in the intensive care unit. Analysis of arterial plasma samples obtained before, during, and 24 h after surgery showed that plasma epinephrine, norepinephrine, cortisol, glucagon, and beta endorphin increased in all patients (P less than 0.05). ⋯ This pattern of neonatal stress responses is distinct from and more extreme than that seen in adult cardiac surgical patients. The four neonates who died postoperatively tended to have higher stress responses intra- and postoperatively despite having been indistinguishable from survivors by the usual clinical and hemodynamic criteria. These preliminary results suggest that neonatal hormonal and metabolic responses to cardiac surgical operations in neonates are extreme and are associated with a high hospital mortality rate.