Abstract
During proportional assist ventilation (PAV), the ventilator pressure is servocontrolled throughout each spontaneous inspiration such that it instantaneously increases in proportion to the airflow (resistive unloading mode), or inspired volume (elastic unloading mode), or both (combined unloading mode). The PAV pressure changes are generated in a closed-loop feedback circuitry commonly using a pneumotachographic signal. In neonates, however, a pneumotachograph increases dead space ventilation, and its signal may include a substantial endotracheal tube leak component. We hypothesized that respiratory inductive plethysmography (RIP) can replace pneumotachography to drive the ventilator during PAV without untoward effects on ventilation or respiratory gas exchange. Ten piglets and five rabbits were supported for 10-min (normal lungs) or 20-min (meconium injured lungs) periods by each of the three PAV modes. In each mode, three test periods were applied in random order with the ventilator driven by the pneumotachograph signal, or the RIP abdominal band signal, or the RIP sum signal of rib cage and abdomen. Interchanging the three input signals did not affect the regularity of spontaneous breathing, and gas exchange was achieved with similar peak and mean airway pressures (ANOVA). However, the RIP sum signal worked adequately only when the relative gains of rib cage and abdominal band signal were calibrated. We conclude that an RIP abdominal band signal can be used to generate PAV, avoiding increased dead space and endotracheal tube leak problems.
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Abbreviations
- AB:
-
RIP signal from abdominal band
- CPAP:
-
continuous positive airway pressure
- Paco2:
-
arterial Pco2
- Pao2:
-
arterial Po2
- PAV:
-
proportional assist ventilation
- RC:
-
RIP signal from rib cage band
- RIP:
-
respiratory inductive plethysmography
- Sum:
-
sum signal of AB and RC
- TCD:
-
total compartmental displacement
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Supported in part by the University of Miami Project New Born.
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Schulze, A., Suguihara, C., Gerhardt, T. et al. Inductance Plethysmography: An Alternative Signal to Servocontrol the Airway Pressure during Proportional Assist Ventilation in Small Animals. Pediatr Res 49, 169–174 (2001). https://doi.org/10.1203/00006450-200102000-00007
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DOI: https://doi.org/10.1203/00006450-200102000-00007
