Critical care medicine
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Critical care medicine · Aug 1992
Comparative StudyValidation of respiratory mechanics software in microprocessor-controlled ventilators.
Several microprocessor-controlled ventilators, available for clinical use, contain optional computer software programs capable of performing near-instantaneous determinations of airway resistance and lung compliance. This study was undertaken to determine the validity of the measurements for airway resistance and lung compliance obtained by the software packages on three microprocessor-controlled ventilators. Three ventilator models were studied. An artificial ventilator-patient circuit was constructed using a test lung and an endotracheal tube. Airway pressure and gas flow curves were recorded using conventional means. Static lung compliance and airway resistance were calculated using standard equations, while automated measurements were obtained from the ventilators. The following parameters were then varied to simulate a wide variety of clinical situations: tidal volume, peak inspiratory flow rate, respiratory rate, endotracheal tube, and test lung compliance. ⋯ The correlation and agreement demonstrated between values of airway resistance and lung compliance measured by the respiratory mechanics software packages and those values derived manually suggest that these software packages may be useful for measuring trends, as well as responding to treatment in the clinical setting. These results apply only to the controlled, mechanical ventilation mode. Further studies are indicated to validate this software in patients capable of generating spontaneous breaths.
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Critical care medicine · Aug 1992
Case ReportsLeft-sided superior vena cava: a not-so-unusual vascular anomaly discovered during central venous and pulmonary artery catheterization.
To report our ICU experience with patients noted to have a left-sided superior vena cava after central venous and pulmonary artery catheterization. ⋯ Left-sided superior vena cava occurs infrequently, most often in association with a right-sided superior vena cava. It is often associated with cardiac septal defects. The intensivist should be aware of its occurrence in order to not mistake catheters placed in it as being present in the arterial circulation or malpositioned outside of the venous circulation.