Small intrapulmonary artery lung prototypes: design, construction, and in vitro water testing

Area of Science:

• Biomedical Engineering
• Cardiovascular Devices
• Gas Exchange

Background:

• Pulmonary artery catheters are used clinically.
• Hollow fibers offer potential for in-vivo gas exchange.
• Optimizing gas transfer in these devices is crucial for efficacy.

Purpose of the Study:

• To investigate the impact of fiber length, manifold number, and gas oscillation on O2 and CO2 transfer.
• To evaluate the performance of hollow fiber prototypes within a pulmonary artery catheter.
• To determine optimal parameters for enhanced gas exchange in cardiovascular applications.

Main Methods:

• Fabrication of hollow fiber prototypes integrated into pulmonary artery catheters.
• Systematic variation of fiber length (0.5-16 cm) and manifold number (1-15).
• Assessment of gas transfer using mass spectrometry and mass flow controllers under steady and oscillating gas flow conditions.

Main Results:

• Gas transfer did not scale linearly with manifold number due to flow maldistribution.
• Oscillating gas pressures (780-76 mmHg absolute at 40 cycles/min) increased CO2 transfer up to 15-fold and O2 transfer up to 2.5-fold.
• Optimal fiber lengths varied with flow conditions: 3 cm (O2) and 1 cm (CO2) for steady flow, and 8 cm for both under oscillatory flow.

Conclusions:

• Gas oscillation is a critical factor for improving gas transfer efficiency in hollow fiber devices.
• Oscillatory flow also mitigates maldistribution issues observed with steady flow.
• Device design, including fiber length and flow dynamics, must be optimized for effective in-vivo gas exchange.