Minute Ventilation Limitations of Two Field Transport Ventilators

Area of Science:

• Mechanical Ventilation
• Respiratory Physiology
• Medical Device Performance Evaluation

Background:

• Transport ventilator performance directly impacts patient safety during critical care.
• Accurate minute ventilation (V_E) delivery is essential for maintaining adequate gas exchange.
• Understanding the limitations of different transport ventilators is vital for clinical decision-making.

Purpose of the Study:

• To compare the minute ventilation (V_E) performance of the MOVES and Uni-Vent 731 transport ventilators.
• To evaluate ventilator performance under varying lung compliance and airway resistance conditions.
• To establish correlations between ventilator settings, pressures, and delivered V_E.

Main Methods:

• Ventilators (MOVES, Uni-Vent 731) were tested using a test lung with adjustable compliance (0.02–0.10 L/cm H₂O) and resistance (none, Rp5, Rp20).
• Tidal volume (V_T) was set at 800 ± 25 mL, and respiratory rate was increased until maximum ventilator settings or auto-PEEP > 5 cm H₂O.
• Respiratory parameters, including peak inspiratory pressure (PIP) and V_E, were measured using a research pneumotachograph.

Main Results:

• Uni-Vent 731 consistently delivered higher V_E (17.7–31.5 L/min) compared to MOVES (11.3–20.2 L/min) across all tested conditions.
• MOVES showed a strong negative correlation between V_E and PIP (r = -0.97), while Uni-Vent exhibited a weak positive correlation (r = 0.05).
• Uni-Vent V_E significantly exceeded MOVES V_E (p = 0.0002) under all experimental conditions.

Conclusions:

• The Uni-Vent 731 demonstrates superior minute ventilation delivery compared to the MOVES transport ventilator.
• Clinical consideration of the Uni-Vent 731 is recommended when patient minute ventilation requirements may exceed the performance predicted by the MOVES regression equation.
• Accurate assessment of transport ventilator capabilities is essential for optimizing patient care and safety.