American journal of respiratory and critical care medicine
-
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)
-
Am. J. Respir. Crit. Care Med. · Mar 1994
ReviewThe American-European Consensus Conference on ARDS. Definitions, mechanisms, relevant outcomes, and clinical trial coordination.
The acute respiratory distress syndrome (ARDS), a process of nonhydrostatic pulmonary edema and hypoxemia associated with a variety of etiologies, carries a high morbidity, mortality (10 to 90%), and financial cost. The reported annual incidence in the United States is 150,000 cases, but this figure has been challenged, and it may be different in Europe. ⋯ The American-European Consensus Committee on ARDS was formed to focus on these issues and on the pathophysiologic mechanisms of the process. It was felt that international coordination between North America and Europe in clinical studies of ARDS was becoming increasingly important in order to address the recent plethora of potential therapeutic agents for the prevention and treatment of ARDS.
-
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)