TY - JOUR

T1 - Volume-cycled decelerating flow; An alternative form of mechanical ventilation

AU - Ravenscraft, S. A.

AU - Burke, W. C.

AU - Marini, J. J.

PY - 1992/1/1

Y1 - 1992/1/1

N2 - The linearly decelerating flow waveform for volume-cycled mechanical ventilation is an option on many modern ventilators. We have developed mathematical models for two available forms of volume-cycled decelerating- flow ventilation (VCDF). These equations use clinician-chosen ventilator settings as inputs (frequency, tidal volume, peak inspiratory flow or inspiratory time fraction, and end-inspiratory pause), and patient-determined inputs which describe the patient's ventilatory impedance (inspiratory [RI] and expiratory [RE] resistance and respiratory system compliance [C]. The equations predict key outcome variables: mean airway pressure; and peak, mean, and end-expiratory alveolar pressures. The mathematical expressions were validated in a mechanical lung analog. Values observed in the test lung were compared to values predicted by the mathematical models for a wide range of ventilator settings and impedance combinations (RI and RE, 5 to 40 cm H2O·s/L; C, 0.02 to 0.10 L/cm H2O). The correspondence between observed and predicted values was generally excellent across the broad range of inputs tested (r≥0.98). Outcome variables were quite sensitive to clinician-chosen inputs over certain critical ranges. Carefully applied, VCDF offers several theoretic advantages for the clinical setting; however, appropriate caution must be exercised to avoid the application of tissue-injuring pressure.

AB - The linearly decelerating flow waveform for volume-cycled mechanical ventilation is an option on many modern ventilators. We have developed mathematical models for two available forms of volume-cycled decelerating- flow ventilation (VCDF). These equations use clinician-chosen ventilator settings as inputs (frequency, tidal volume, peak inspiratory flow or inspiratory time fraction, and end-inspiratory pause), and patient-determined inputs which describe the patient's ventilatory impedance (inspiratory [RI] and expiratory [RE] resistance and respiratory system compliance [C]. The equations predict key outcome variables: mean airway pressure; and peak, mean, and end-expiratory alveolar pressures. The mathematical expressions were validated in a mechanical lung analog. Values observed in the test lung were compared to values predicted by the mathematical models for a wide range of ventilator settings and impedance combinations (RI and RE, 5 to 40 cm H2O·s/L; C, 0.02 to 0.10 L/cm H2O). The correspondence between observed and predicted values was generally excellent across the broad range of inputs tested (r≥0.98). Outcome variables were quite sensitive to clinician-chosen inputs over certain critical ranges. Carefully applied, VCDF offers several theoretic advantages for the clinical setting; however, appropriate caution must be exercised to avoid the application of tissue-injuring pressure.

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U2 - 10.1378/chest.101.5.1342

DO - 10.1378/chest.101.5.1342

M3 - Article

C2 - 1582295

AN - SCOPUS:0026664127

VL - 101

SP - 1342

EP - 1351

JO - Diseases of the chest

JF - Diseases of the chest

SN - 0012-3692

IS - 5

ER -