Anesthesiology
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Randomized Controlled Trial Clinical Trial
The impact of systemic vasoconstrictors on the cerebral circulation of anesthetized patients.
BACKGROUND. The effect of vasoconstrictors on intracerebral hemodynamics in anesthetized patients is controversial. The influence of phenylephrine and norepinephrine on the cerebral circulation was investigated in isoflurane- or propofol-anesthetized patients using transcranial Doppler ultrasonography. ⋯ The results of the present study indicate that norepinephrine and phenylephrine do not directly affect intracranial hemodynamics in anesthetized patients, but rather that hemodynamic changes observed with vasoconstrictors reflect the effect of the background anesthetic agents on cerebral pressure autoregulation.
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Randomized Controlled Trial Clinical Trial
A comparison of the respiratory effects of sevoflurane and halothane in infants and young children.
This study compared the respiratory effects of sevoflurane with those of halothane in anesthetized infants and young children. ⋯ Minute ventilation and respiratory frequency were lower in infants during 1 MAC sevoflurane in nitrous oxide than during halothane anesthesia. However, these differences may not be clinically relevant at these concentrations, given the modest increase in PETCO2. Differences in parameters of breath timing and shape between sevoflurane and halothane suggest different effects of these anesthetic agents on ventilatory control.
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Comparative Study
Comparison of pH-stat and alpha-stat cardiopulmonary bypass on cerebral oxygenation and blood flow in relation to hypothermic circulatory arrest in piglets.
Deep hypothermic circulatory arrest is used in neonatal cardiac surgery. Recent work has suggested improved neurologic recovery after deep hypothermic arrest with pH-stat cardiopulmonary bypass (CPB) compared with alpha-stat CPB. This study examined cortical oxygen saturation (ScO2), cortical blood flow (CBF), and cortical physiologic recovery in relation to deep hypothermic arrest with alpha-stat or pH-stat CPB. ⋯ Cortical deoxygenation during hypothermic arrest was slower after pH-stat CPB. pH-stat bypass increased the prearrest ScO2 and arrest ScO2 half-life, to increase the cortical oxygen supply and slow cortical oxygen consumption. Improved cortical physiologic recovery after hypothermic arrest was suggested with pH-stat management.
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Techniques are needed to assess anesthesiologists' performance when responding to critical events. Patient simulators allow presentation of similar crisis situations to different clinicians. This study evaluated ratings of performance, and the interrater variability of the ratings, made by multiple independent observers viewing videotapes of simulated crises. ⋯ Both technical and behavioral performance can be assessed from videotapes of simulations. The behavioral rating system can be improved; one particular difficulty was aggregating a single rating for a behavior that fluctuated over time. These performance assessment tools might be useful for educational research or for tracking a resident's progress. The rating system needs more refinement before it can be used to assess clinical competence for residency graduation or board certification.
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BACKGROUND. Injection of local anesthetic into cerebrospinal fluid (CSF) produces anesthesia of unpredictable extent and duration. Although many factors have been identified that affect the extent of spinal anesthesia, correlations are relatively poor and the extent of spread remains unpredictable. This study was designed to determine whether variability in the volume of lumbosacral CSF among individuals is a contributing factor in the variability of spinal anesthesia. ⋯ Variability in lumbosacral CSF volume is the most important factor identified to date that contributes to the variability in the spread of spinal sensory anesthesia.