Critical care medicine
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Critical care medicine · Feb 1994
Cerebrovascular response to carbon dioxide in lambs receiving extracorporeal membrane oxygenation.
To determine if the institution of extracorporeal membrane oxygenation (ECMO) alters the cerebrovascular response to changes in PaCO2. ⋯ The cerebrovascular response to changes in PaCO2 was unaffected by ECMO.
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To describe the typical ranges for central venous oxygen saturation and PO2 in a group of critically ill neonates and the relationship of these measurements to measurements of arterial oxygenation and indicators of oxygen supply and demand. ⋯ We conclude that measurement of central venous oxygenation in ill neonates may reflect more accurately the oxygen supply and demand status of the neonate than measurement of arterial oxygenation alone.
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Critical care medicine · Feb 1994
Variability of cardiac output over time in medical intensive care unit patients.
To determine the amount of spontaneous variability of cardiac output over time in critically ill patients, and to determine the effect of mechanical ventilation on cardiac output variability over time. ⋯ The spontaneous variability of cardiac output should be considered when interpreting two cardiac output determinations made at separate times. Due to spontaneous variability alone, a patient with a baseline cardiac output of 10.0 L/min would be expected (95% confidence interval) to have a cardiac output range of 9.2 to 10.8 L/min if covariables were stable, and a range of at least 8.8 to 11.2 L/min if covariables were unstable. Patients who were mechanically ventilated displayed less variability than patients who were breathing spontaneously.
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Critical care medicine · Feb 1994
Effects of dobutamine and norepinephrine on oxygen availability in tamponade-induced stagnant hypoxia: a prospective, randomized, controlled study.
To explore the effects of dobutamine and norepinephrine on the global cardiovascular response and on the relationship between oxygen uptake (VO2) and oxygen delivery (DO2) during an acute reduction in blood flow associated with tamponade. ⋯ During low-flow states associated with tamponade, both dobutamine and norepinephrine at the dose used increased cardiac index, DO2, and VO2, but dobutamine delayed the onset of tissue hypoxia by further increasing blood flow and oxygen availability. In the conditions of the present study, neither agent significantly influenced the oxygen extraction capabilities of the body.
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Critical care medicine · Feb 1994
Combining pressure-limiting and volume-cycling features in a patient-interactive mechanical breath.
To combine the patient synchrony effects of pressure-limited breath delivery strategies with the volume guarantee of volume-cycled breath delivery strategies, we designed a positive-pressure breath that incorporates both features. This breath is patient triggered and can be pressure limited. Breath termination (i.e., cycling) can either be flow- or volume-cycled, depending on whether a target volume has been attained. The pressure-limiting features are further enhanced by the capability to adjust demand-valve responsiveness at breath initiation. ⋯ Flow dyssynchrony during fixed-flow, volume-cycled assisted breaths in patients with active ventilatory drives can be improved with this breath design while a guaranteed tidal volume is maintained. In addition, this combination breath can provide a volume "safety net" for patients in whom partial support with pressure-support ventilation is desired.