Fiber Bundle Design for an Integrated Wearable Artificial Lung

Area of Science:

• Biomedical Engineering
• Respiratory Medicine
• Medical Device Development

Background:

• End-stage lung failure, including ARDS and COPD, necessitates mechanical ventilation (MV) or ECMO.
• High morbidity and mortality are linked to prolonged wait times for lung transplantation.
• Patient ambulation is associated with improved post-transplant outcomes in lung failure patients.

Purpose of the Study:

• To design and validate a hollow fiber membrane (HFM) bundle for the Pittsburgh Ambulatory Assist Lung (PAAL).
• To achieve a target oxygenation of 180 ml/min for a wearable artificial lung enabling ambulation.
• To model and experimentally determine the optimal form factor for the HFM bundle.

Main Methods:

• Mathematical modeling based on mass transfer correlations to predict oxygenation efficiency.
• Fabrication and in vitro testing of three benchmark HFM bundles for blood gas exchange.
• Hemolysis studies to assess biocompatibility at specified blood flow rates.

Main Results:

• Model predictions showed a 3% to 17.5% difference compared to experimental results for benchmark bundles.
• A 1.75-inch diameter bundle with 0.65 m² surface area was predicted to achieve 180 ml/min oxygenation at 3.5 L/min blood flow.
• Achieved oxygenation efficiency of 278 ml/min/m² with a Normalized Index of Hemolysis (NIH) below 0.05 g/100 L.

Conclusions:

• The developed HFM bundle design is suitable for the PAAL wearable artificial lung.
• The study validates a predictive model for HFM oxygenation efficiency and biocompatibility.
• Further development is underway to integrate the HFM bundle into a functional PAAL prototype.