Anesthesia and analgesia
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Anesthesia and analgesia · Jul 1993
Reevaluation of a maneuver to visualize the anterior larynx after intubation.
Confirmation of translaryngeal placement of the tracheal tube can be unexpectedly difficult. This study examined the usefulness of displacing the larynx posteriorly with the tracheal tube during laryngoscopy with a straight laryngoscope blade to confirm tracheal tube placement. One hundred ASA Classes I, II, or III patients presenting for elective surgery whose normal anesthetic care included placement of an orotracheal tube via direct laryngoscopy were enrolled in this institutionally approved study after giving their written, informed consent. ⋯ Thus, the tracheal tube actually was not seen to pass between these patients' vocal cords. Use of the maneuver resulted in improved visualization of the intubated larynx in 12 of these patients, and confirmed tracheal intubation. This maneuver is recommended as an aid to the anesthesiologist in the confirmation of tracheal intubation.
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To investigate how epidural anesthesia changes intrathoracic gas volume, high epidural anesthesia was administered to five pentobarbital-anesthetized dogs lying supine, and the total intrathoracic volume at end-expiration was measured with a high-speed three-dimensional x-ray scanner. The amount of gas in the lungs at end-expiration [the functional residual capacity (FRC)] was measured with a nitrogen washout technique, and the intrathoracic tissue volume, including the intrathoracic blood volume, was calculated as the difference between intrathoracic volume at end-expiration and FRC. ⋯ We conclude that increases in FRC caused by epidural anesthesia in anesthetized dogs lying supine may be minimized by a concurrent increase in intrathoracic blood volume. These results suggest that measurements of thoracic gas volume alone may be insufficient to describe chest wall responses to epidural anesthesia.