American journal of respiratory and critical care medicine
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Am. J. Respir. Crit. Care Med. · Mar 1994
Comparative StudyFeasibility of continuous oxygen delivery and cardiac output measurement by application of the Fick principle.
Continuous mixed venous oxygen saturation (SVO2) measurements from fiberoptic pulmonary artery catheters, arterial oxygen saturation (SaO2) measurements from pulse oximetry, and minute-by-minute oxygen consumption (VO2) measurements from indirect calorimetry can be used for near-continuous estimation of cardiac output (Qt) and oxygen delivery (DO2) by application of the Fick Principle. Assumptions required for calculation of blood oxygen contents include constant hemoglobin concentration (Hgb) and constant or negligible physically dissolved oxygen. First, the influence of these assumptions on continuous Qt and DO2 determinations was tested. ⋯ These factors increased with increasing SVO2, and thus, Qt and DO2 became increasingly unreliable as oxygen extraction fell. Third, we compared continuous measurements of Qt and DO2 with intermittent measurements made by thermodilution cardiac output and blood sampling, and found correlation coefficients of 0.85 for Qt and 0.89 for DO2. Fourth, common measurement errors in VO2 and DO2 calculated in this way were found to bias regressions between VO2 and DO2, and this bias could be minimized only if the DO2 range were high and SVO2 were low.(ABSTRACT TRUNCATED AT 250 WORDS)
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Am. J. Respir. Crit. Care Med. · Mar 1994
Ventilatory responses during wakefulness in children with obstructive sleep apnea.
The pathophysiology of the obstructive sleep apnea syndrome (OSAS) is not fully understood. In children, airway obstruction secondary to tonsilloadenoidal hypertrophy is the leading cause of OSAS. However, not all children with tonsilloadenoidal hypertrophy develop OSAS. ⋯ There was a weak inverse correlation between the slope of the hypercapnic ventilatory response and the duration of hypoventilation during polysomnography (r = -0.44, p < 0.05). We conclude that children with OSAS have normal ventilatory responses to hypercapnia, and they may have normal ventilatory responses to hypoxia. We speculate that abnormal central ventilatory drive plays little if any role in the pathogenesis of pediatric OSAS.(ABSTRACT TRUNCATED AT 250 WORDS)
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Am. J. Respir. Crit. Care Med. · Feb 1994
Randomized Controlled Trial Comparative Study Clinical TrialRandomized clinical trial of pressure-controlled inverse ratio ventilation and extracorporeal CO2 removal for adult respiratory distress syndrome.
The impact of a new therapy that includes pressure-controlled inverse ratio ventilation followed by extracorporeal CO2 removal on the survival of patients with severe ARDS was evaluated in a randomized controlled clinical trial. Computerized protocols generated around-the-clock instructions for management of arterial oxygenation to assure equivalent intensity of care for patients randomized to the new therapy limb and those randomized to the control, mechanical ventilation limb. We randomized 40 patients with severe ARDS who met the ECMO entry criteria. ⋯ We conclude that there was no significant difference in survival between the mechanical ventilation and the extracorporeal CO2 removal groups. We do not recommend extracorporeal support as a therapy for ARDS. Extracorporeal support for ARDS should be restricted to controlled clinical trials.
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Am. J. Respir. Crit. Care Med. · Feb 1994
Editorial Comment Randomized Controlled Trial Comparative Study Clinical TrialAn anecdote is an anecdote is an anecdote ... but a clinical trial is data.