Critical care medicine
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Critical care medicine · Oct 1985
Pulmonary interstitial emphysema in the adult respiratory distress syndrome.
Chest x-rays of 15 patients with the adult respiratory distress syndrome (ARDS) were evaluated retrospectively for the presence of pulmonary interstitial emphysema (PIE). PIE was radiographically detected in 13 (88%) patients, 10 (77%) of whom also had pneumothorax. In five of these, pneumothorax occurred within the first 12 h after interstitial emphysema appeared. ⋯ The appearance of PIE and its complications, i.e., pneumothorax and pneumomediastinum, occurred over a wide range of mean airway pressures and positive end-expiratory pressures; there was no direct relationship between barotrauma and mean airway pressure or positive end-expiratory pressure. In 12 of the 13 patients all manifestations of barotrauma occurred at or above a peak airway pressure of 40 cm H2O, indicating a threshold level of peak airway pressure which would place the ARDS patient at high risk for developing pulmonary barotrauma. Time on the respirator at peak airway pressures above 40 cm H2O, clinical severity of ARDS, and associated pulmonary pathology (emphysema, bacterial pneumonia) appear to play a role in developing barotrauma.
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Critical care medicine · Oct 1985
Real-time analysis of the change in arterial oxygen tension during endotracheal suction with a fiberoptic bronchoscope.
An intra-arterial Clark-type polarographic oxygen electrode was used with a fiberoptic bronchoscope for real-time analysis of the PO2 change during 1 min of suction in patients spontaneously breathing oxygen. There was a strong correlation between values obtained from the intra-arterial electrode (PiO2) and those from blood samples (PaO2), before and at the end of suction; the PiO2/PaO2 ratio was close to one. ⋯ This drop in PiO2 was partially attenuated by providing oxygen with high-frequency jet ventilation and was almost completely attenuated by the use of a suction adaptor. Changes in the inspired oxygen concentration indicated the importance of keeping this variable constant during suction to prevent hypoxemia.
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Critical care medicine · Oct 1985
Arterial to end-tidal CO2 gradients during spontaneous breathing, intermittent positive-pressure ventilation and jet ventilation.
Arterial to end-tidal CO2 tension gradients were measured in 18 dogs during spontaneous breathing (SB), intermittent positive-pressure ventilation (IPPV), and both low-frequency and high-frequency jet ventilation (LFJV and HFJV). The dogs were anesthetized with nembutal and permitted to breathe spontaneously through an 8-mm internal diameter endotracheal tube; blood gas tensions, cardiac output, and end-tidal CO2 partial pressure (PetCO2) were measured. IPPV, LFJV, and HFJV were then instituted in a random sequence and measurements repeated. ⋯ The mean PaCO2-PetCO2 gradient was 3.7 +/- 1 (SD), 12.6 +/- 5.0, and 24.3 +/- 8 torr during IPPV, LFJV and HFJV, respectively. The large gradients during LFJV and HFJV were not produced by dilution of tracheal CO2 by entrained air or by oxygen delivered by the jet. These results suggest that both LFJV and HFJV may be associated with a large PaCO2-PetCO2 gradient.
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A patient with an apparent dilantin and phenobarbital overdose displayed hypotension and oliguria resistant to usual cardiotonic drugs and volume loading. In addition, she required an unusually high dose of epinephrine for resuscitation. Metoprolol, a beta-blocker not included on the drug screen, was subsequently implicated. An overdose of this drug should be suspected in patients whose hypotension is resistant to usually effective doses of inotropic and chronotropic agents.