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The HPV response is different with constant pressure vs constant flow perfusion
W R Clarke1, C M Haberkern, J Zeh
1Department of Anesthesiology, University of Washington School of Medicine, Seattle.
Respiration Physiology
|October 1, 1993
Summary
Hypoxic pulmonary vasoconstriction (HPV) is stronger and lasts longer when pulmonary artery pressure is kept constant, compared to when blood flow is constant. This finding impacts how we study lung circulation.
Area of Science:
- Physiology
- Cardiovascular Research
- Pulmonary Medicine
Background:
- Hypoxic pulmonary vasoconstriction (HPV) is a critical circulatory response.
- HPV can manifest as increased pulmonary artery pressure or flow diversion.
- The influence of perfusion conditions on HPV magnitude is not fully understood.
Purpose of the Study:
- To test if the magnitude of HPV differs between constant flow and constant pressure perfusion.
- To investigate the impact of perfusion conditions on HPV response duration.
Main Methods:
- Isolated, perfused rabbit lungs were used.
- Four levels of hypoxia (12%, 6%, 3%, 0% oxygen) were applied.
- HPV response was measured under constant flow and constant pressure conditions.
Main Results:
- HPV response was of greater magnitude under constant pressure perfusion.
- The HPV response was more sustained under constant pressure perfusion.
- A notable difference in HPV magnitude and duration was observed between the two perfusion conditions.
Conclusions:
- Perfusion conditions significantly influence the magnitude and duration of HPV.
- Constant pressure perfusion reveals a more robust HPV response compared to constant flow.
- Findings are relevant for interpreting studies of perinatal and mature pulmonary circulation.