Chest
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The patient had classic ECG changes of hypothermia (sinus bradycardia, prolonged PR interval, prolonged QT interval, and Osborn waves). These changes occurred in hypothermia resulting from sepsis, without exposure being a factor. Documentation of Osborn waves in this clinical setting supports the theory that they result as a direct consequence of myocardial cooling.
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The relationship between changes in cardiac output and intrapulmonary shunt associated with mechanical ventilation was evaluated in 20 patients with the adult respiratory distress syndrome (ARDS). The distribution of ventilation-perfusion (VA/Q) ratios and the level of intrapulmonary shunt was determined by the multiple inert gas technique. Pulmonary blood flow was distributed predominantly to either effective gas-exchanging units or shunt units. ⋯ Changes in shunt and cardiac output were quantitatively and qualitatively silimar and a strong correlation was found between changes in shunt and cardiac output with both PEEP and high tidal volumes (r = 0.76). Cardiac output depression associated with tese modes of ventilation appears to be a mechanism of shunt reduction in ARDS. Interpretation of improvements in gas exchange in ARDS must take into account concomitant hemodynamic changes.