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David J Dries

Publications and source records attributed to David J Dries.

7 recordsLinked to original sources
PubMed2002

Oscillations and noise: inherent instability of pressure support ventilation?

Pressure support ventilation (PSV) is almost universally employed in the management of actively breathing ventilated patients with acute respiratory failure. In this partial support mode of ventilation, a fixed pressure is applied to the airway opening, and flow delivery is monitored by the ventilator. Inspiration is terminated when measured inspiratory flow falls below a set fraction of the peak flow rate (flow cutoff); the ventilator then cycles to a lower pressure and expiration commences. We used linear and nonlinear mathematical models to investigate the dynamic behavior of pressure support ventilation and confirmed the predicted behavior using a test lung. Our mathematical and laboratory analyses indicate that pressure support ventilation in the setting of airflow obstruction can be accompanied by marked variations in tidal volume and end-expiratory alveolar pressure, even when subject effort is unvarying. Unstable behavior was observed in the simplest plausible linear mathematical model and is an inherent consequence of the underlying dynamics of this mode of ventilation. The mechanism underlying the observed instability is "feed forward" behavior mediated by oscillatory elevation in end-expiratory pressure. In both mathematical and mechanical models, unstable behavior occurred at impedance values and ventilator settings that are clinically realistic.

Adult↗
PubMed2002

Recent advances in emergency life support.

With additional international input, recent changes in emergency life support are reflected in updated guidelines for Advanced Cardiac Life Support (ACLS) from the American Heart Association and new technology in the arena of vascular access and emergency airway management. These changes will expand nurses' ability to provide advanced levels of care, even in the prehospital situation, and represent a more rigorous evidence-based approach than ever before. As early morbidity and mortality in emergency situations are frequently associated with complications associated with airway management and vascular access, recent development in these areas are reviewed along with evolution in ACLS guidelines.

Adult↗
PubMed2002

Pulmonary microvascular fracture in a patient with acute respiratory distress syndrome.

OBJECTIVE: To present electron micrographs of lung tissue obtained from a patient exposed to high ventilatory pressures in the context of pulmonary dysfunction and pulmonary hypertension. DESIGN: Case report. SETTING: Adult intensive care unit of a university-affiliated teaching hospital. PATIENTS: A patient exposed to high-pressure mechanical ventilation during support for acute respiratory distress syndrome; the acute respiratory distress syndrome in this case was secondary to septic shock. MEASUREMENTS AND MAIN RESULTS: Scanning electron micrographs of lung tissue, focusing on the internal alveolar surfaces. FINDINGS: Multiple gross disruptions of the alveolar walls, suggestive of stress fractures. CONCLUSION: High-pressure mechanical ventilation may promote fracturing of the alveolar blood:airspace barrier.

Aged↗