Critical care medicine
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Critical care medicine · Jun 1986
Determinants of alveolar ventilation during high-frequency transtracheal jet ventilation in dogs.
The effectiveness of transtracheal jet ventilation is a function of gas delivery pressure (drive pressure), duty cycle (insufflation time/total cycle time), and respiratory frequency. Nine dogs, anesthetized with sodium pentobarbital, were ventilated through a cricothyrotomy cannula using a controller that allowed separate setting of drive pressure, duty cycle, and frequency. PaO2 and PaCO2 were measured after achieving steady-state gas exchange at 15 to 22 different combinations of drive pressure, duty cycle, and frequency in each dog. ⋯ The distribution of air flow between alveolar and physiologic dead space, upper airway leakage, and entrainment was determined for each set of conditions. Changes in alveolar ventilation corresponding to the blood gas changes resulted from interaction of dead-space ventilation and upper airway leakage, which varied with breath duration. Decreases in leakage during short breaths tended to compensate for the increased fractional dead-space ventilation at high frequency, thus minimizing the effects of frequency changes on gas exchange.
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We studied the effects of coenzyme Q10 pretreatment on both pulmonary function and chemical mediators during endotoxin shock in dogs. Coenzyme Q10 pretreatment inhibited disturbances in peak airway pressure, total compliance of lung plus chest wall, lung clearance index, plasma histamine, base excess, and lactate; however, it had little effect on the circulation. The mechanism of coenzyme Q10's significant effects on pulmonary function during endotoxin shock is presently unknown.