David W. Kaczka

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OBJECTIVE Acute respiratory distress syndrome and acute lung injury are characterized by heterogeneous flooding/collapse of lung tissue. An emerging concept for managing these diseases is to set mechanical ventilation so as to minimize the impact of disease heterogeneity on lung mechanical stress and ventilation distribution. The goal of this study was to(More)
We examined the partitioning of total lung resistance (RL) into airway resistance (Raw) and tissue resistance (Rti) in patients with mild to moderate asthma (baseline FEV1, 54 to 91% of predicted) before and after albuterol inhalation. An optimal ventilator waveform was used to measure RL and lung elastance (EL) in 21 asthmatics from approximately 0.1 to 8(More)
The contribution of airway resistance (Raw) and tissue resistance (Rti) to total lung resistance (RL) during breathing in humans is poorly understood. We have recently developed a method for separating Raw and Rti from measurements of RL and lung elastance (EL) alone. In nine healthy, awake subjects, we applied a broad-band optimal ventilator waveform (OVW)(More)
Since its introduction in the 1950s, the forced oscillation technique (FOT) and the measurement of respiratory impedance have evolved into powerful tools for the assessment of various mechanical phenomena in the mammalian lung during health and disease. In this review, we highlight the most recent developments in instrumentation, signal processing, and(More)
Measurements of lung resistance and elastance (RL and EL) from 0.1 to 8 Hz reflect both the mean level and pattern of lung constriction. The goal of this study was to establish a relation between a deep inspiration (DI) and the heterogeneity of constriction in healthy versus asthmatic subjects. Constriction pattern was assessed from measurements of the RL(More)
We present a broad-band optimal ventilator waveform (OVW), the concept of which was to create a computer-driven ventilator waveform containing increased energy at specific frequencies (f). Values of f were chosen such that nonlinear harmonic distortion and intermodulation were minimized. The phases at each f were then optimized such that the resulting flow(More)
OBJECTIVE a) Characterize how ventilator and patient variables affect tidal volume during high-frequency oscillatory ventilation; and b) measure tidal volumes in adults with acute respiratory distress syndrome during high-frequency oscillatory ventilation. DESIGN Observational study. SETTING Research laboratory and medical intensive care unit. (More)
Heterogeneity of regional lung mechanics is an important determinant of the work of breathing and may be a risk factor for ventilator associated lung injury. The ability to accurately assess heterogeneity may have important implications for monitoring disease progression and optimizing ventilator settings. Inverse modeling approaches, when applied to(More)
To test an approach for measuring respiratory system resistance (R) and elastance (E) during non-sinusoidal forcing, we measured airway and esophageal pressures and flow at the trachea of 9 anesthetized-paralyzed dogs during sinusoidal forcing (SF) and 4 types of non-sinusoidal forcings at 0.15 and 0.6 Hz and 300 ml tidal volume. During SF, calculations of(More)
The ability to maintain adequate gas exchange depends on the relatively homogeneous distribution of inhaled gas throughout the lung. Structural alterations associated with many respiratory diseases may significantly depress this function during tidal breathing. These alterations frequently occur in a heterogeneous manner due to complex, emergent(More)