Critical care medicine
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Critical care medicine · Sep 1984
Case ReportsHigh-frequency jet ventilation for differential lung ventilation.
High-frequency jet ventilation using a jet injector located at the right mainstem bronchus was superimposed on standard mechanical ventilation to ventilate the injured lung of a patient with unilateral massive atelectasis secondary to pulmonary hemorrhage. This technique of differential ventilation markedly improved arterial oxygenation in this patient and may prove to be a simpler modality of respiratory support in patients who have respiratory failure from unilateral lung disease.
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Critical care medicine · Sep 1984
Comparative StudyHemodynamic effects of continuous positive-pressure ventilation and high-frequency jet ventilation with positive end-expiratory pressure in normal dogs.
The hemodynamic effects of high-frequency jet ventilation (HFJV) at 60, 120, 240, and 480 breath/min, and conventional ventilation at 15 breath/min were compared in 6 anesthetized, paralyzed dogs, at 0, 10, and 20 cm H2O of positive end-expiratory pressure (PEEP). On HFJV at the same inspired oxygen, PaCO2, and PEEP levels, hemodynamic function improved significantly. ⋯ When PEEP was applied, hemodynamic function improved even when mean airway pressure was maintained constant. The findings suggest that lung volume was smaller during HFJV, and/or that lung volume changes during each respiratory cycle contributed to differences in venous return and ventricular function.
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Critical care medicine · Sep 1984
Comparative StudyHigh-frequency positive-pressure ventilation with the MA-1 ventilator.
A conventional, low-frequency ventilator was modified to ventilate dogs at high frequencies of 85 to 185 cycle/min while cardiovascular and pulmonary variables were monitored. Although gas transport was adequate, cardiac output was diminished when compared to low-frequency ventilation. The addition of an in-line pneumotachograph markedly increased PaCO2 during high-frequency ventilation. Carbon dioxide transport was primarily dependent upon the magnitude of the tidal volume at all high frequencies tested.
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Critical care medicine · Sep 1984
Airway pressure as a measure of gas exchange during high-frequency jet ventilation.
Airway pressure during high-frequency jet ventilation (HFJV) reflects safety, ventilator performance, and gas exchange. The value of airway pressure as a monitoring and control variable for predicting the effectiveness of gas exchange was examined in 2 studies using healthy dogs. In the first study, HFJV was delivered to the airway via an extra lumen in the wall of an endotracheal tube, at a frequency of 150 cycle/min and 30% inspiratory time. ⋯ The airway pressure difference correlated strongly with efficiency of gas exchange for both CO2 elimination and oxygenation. Mean and end-expiratory pressures showed little influence over moderate ranges, but use of 15 cm H2O of PEEP decreased efficiency of both CO2 elimination and oxygenation, presumably due to increased dead space because of lung overdistension. We conclude that the airway pressure difference, measured as far distal in the airway as is safe and practical, can be useful for monitoring and controlling HFJV.