Anesthesia and analgesia
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Anesthesia and analgesia · Jul 1993
Comparative StudyHeat loss in humans covered with cotton hospital blankets.
We evaluated mean skin temperature, cutaneous heat loss, and perceived warmth in six volunteers covered with one or three cotton hospital blankets, warmed or unwarmed. Mean skin temperatures were significantly higher during each treatment than during the control periods preceding each blanket application. Total cutaneous heat loss during the control period was 81 +/- 11 watts. ⋯ These data indicate that increasing the number of covering blankets from one to three decreases heat loss only slightly. Similarly, warming the blankets is relatively ineffective and the benefit short-lived. The reduction in heat loss, even by three warmed blankets replaced at 10-min intervals, was small compared to that provided by available active warming systems.
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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.