Critical care medicine
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Critical care medicine · Aug 1983
Static pressure-volume curves and effect of positive end-expiratory pressure on gas exchange in adult respiratory distress syndrome.
Fifteen patients with adult respiratory distress syndrome (ARDS) were studied: 11 in the early stage of ARDS (group 1); 4 in the late stage (group 2). The inspiratory and expiratory static pressure-volume (P-V) curves of the respiratory system were compared to the pulmonary shunt (Qsp/Qt) when PEEP was increased; cardiac output was kept constant. ⋯ Expiratory P-V curve can be used to determine: first, whether a patient should be ventilated with PEEP; second, the PEEP level which can be set on the respirator. In group 1 patients, when PEEP was set to a value corresponding to the inflexion point, i.e., the point of departure from the exponential shape (mean value 14.6 +/- 2.8 cm H2O), Qsp/Qt compared to zero PEEP was abruptly decreased to 87.6 +/- 6%; further increase in PEEP had little advantage.
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Critical care medicine · Aug 1983
Comparative StudyIntermittent positive pressure ventilation and high frequency ventilation in dogs with experimental bronchopleural fistulae.
This study evaluated respiratory and cardiovascular responses of canines in whom bilateral bronchopleural fistulae were created surgically, and in whom ventilation was varied between intermittent positive pressure ventilation (IPPV) and high frequency ventilation (HFV). An Emerson prototype ventilator was used for HFV at rates of 300-1400/min at driving pressures of 2.5, 5.0, and 10 psi. ⋯ Ventilation during IPPV with the fistula open resulted in a statistically significant increase in PaCO2 and a decrease in PaO2 when compared to both HFV modes. Variations in cardiac function in these open-chested animals were insignificant for all variables tested except pulmonary artery pressures which rose significantly in the IPPV group.
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Critical care medicine · Aug 1983
Case ReportsDiagram for easy volume setting of an infant ventilator.
A pressure-volume diagram with isocompliance lines allows quick, accurate volume setting of the piston-driven infant ventilator Bourns LS. A line parallel with the machine compliance line and an intercept on the ordinate equal to the tidal volume, serves as a guideline for initial volume setting and subsequent adaptation according to the patient's lung compliance. This diagram is particularly useful when the lung compliance is low; changes consistently during controlled ventilation.
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Critical care medicine · Jul 1983
Comparative Study Clinical TrialPhysiologic implications of high frequency jet ventilation techniques.
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Critical care medicine · Jul 1983
Comparative StudyPhysiologic requirements during rewarming: suppression of the shivering response.
Intraoperative hypothermia has become a common occurrence. Postoperative rewarming often is accompanied by shivering and results in increased metabolic and circulatory demands. We examined the metabolic, hemodynamic, and biochemical variables in 2 groups of hypothermic (greater than 35.8 degrees C) patients requiring mechanical ventilation after a major operation. ⋯ Suppression of the shivering by metocurine increased rewarming time significantly and decreased VCO2, VO2, HR, rate pressure product, mean arterial pressure (MAP), and the O2 cost of rewarming. Thus, the elimination of shivering during postoperative rewarming is associated with a decrease in caloric, metabolic demands and myocardial work (as assessed by the rate pressure product) while rewarming time is prolonged. In the postoperative, hypothermic, critically ill patient, suppression of the shivering response in selected patients may be indicated.