Anesthesiology
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Comparative Study Clinical Trial
Cardiac output by transesophageal echocardiography using continuous-wave Doppler across the aortic valve.
The use of transesophageal echocardiography for the determination of cardiac output (CO) has been limited to date. We assessed the capability of aortic continuous-wave Doppler transesophageal echocardiography to determine CO (DCO) in a transgastric long-axis imaging plane of the heart by comparing DCO to thermodilution CO (TCO). ⋯ Compared to thermodilution, continuous-wave Doppler measurements of blood flow velocity across the aortic valve in the transesophageal echocardiographic transgastric view allow accurate CO determination.
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Prevention of hypothermia is an important aspect of anesthetic management. Methods used for its prevention may, however, cause cutaneous burns. We reviewed the American Society of Anesthesiologists (ASA) Closed Claims Project database to determine if there were recurrent patterns of injury arising from intraoperative warming methods. ⋯ Intravenous fluid bags or bottles warmed in an operating room oven represent a hazard to anesthetized patients. Because intravenous fluid bags or bottles are not an efficient method of patient warming, there seems to be little justification for their use.
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Clinical Trial Controlled Clinical Trial
Minimum alveolar concentration of isoflurane for tracheal extubation in deeply anesthetized children.
The end-tidal anesthetic gas concentration required to prevent the anesthetized patient from coughing or moving during or immediately after tracheal extubation is not known. ⋯ In 50% of anesthetized children age 4-9 yr tracheal extubation may be accomplished without coughing or moving at 1.27% end-tidal isoflurane concentration.
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Normal thermoregulatory function is believed to be modulated by thermosensitive neurons in the preoptic region of the anterior hypothalamus and other sites within the central nervous system including the spinal cord. Previous evidence has demonstrated modulation of segmental spinal cord thermoregulatory mechanisms from more rostral central nervous system sites. The ability of the volatile anesthetics to disrupt normal thermoregulatory function and produce shivering-like activity during emergence is well documented. The purpose of the current investigation was to examine the action purpose of the current investigation was to examine the action of the volatile anesthetics halothane, isoflurane, and enflurane on thermoregulatory responses produced at the preoptic region and spinal cord. ⋯ The ability of preoptic region heating and cooling to modulate postanesthetic shivering implies that while thermoregulatory pathways remain intact, volatile anesthetics produce an imprecision in the control of thermoregulatory responses at the level of the anterior hypothalamus. Attenuation of shivering-like responses generated at spinal cord levels in pontine-transected cats implies a significant blunting action of thermoregulatory response mechanisms at the level of the spinal cord or lower brain stem.
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Anesthetic doses of dexmedetomidine (DMED), a highly selective alpha 2 agonist, are not well tolerated hemodynamically. The combination of an opioid with DMED might reduce the dosage requirements for each drug and thereby allow the same anesthetic depth to be achieved with lesser degrees of their individual side effects. ⋯ There was a positive interaction, additive or synergistic, between DMED and fentanyl with respect to their enflurane-sparing effects. The interaction allowed the same depth of anesthesia to be achieved by lower doses of all three drugs, potentially limiting the intensity of their individual side effects. However, the presence of fentanyl increased the degree of bradycardia induced by DMED.