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Platelet-activating factor causes ventilation-perfusion mismatch in humans

R Rodriguez-Roisin1, M A Félez, K F Chung

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Inhaled platelet-activating factor (PAF) causes immediate ventilation-perfusion (VA/Q) inequality and impairs gas exchange in healthy individuals. This suggests PAF is a key mediator of lung inflammation.

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Area of Science:

  • Pulmonary Medicine
  • Respiratory Physiology
  • Inflammation Research

Background:

  • Platelet-activating factor (PAF) is a potent inflammatory mediator.
  • The role of PAF in inducing acute lung injury and gas exchange abnormalities in humans requires further investigation.

Purpose of the Study:

  • To investigate the effects of inhaled aerosolized PAF on ventilation-perfusion (VA/Q) relationships, hemodynamics, and respiratory system resistance in healthy humans.
  • To compare the effects of PAF with its inactive precursor, lyso-PAF.

Main Methods:

  • 14 healthy subjects inhaled aerosolized PAF (24 micrograms).
  • 10 healthy subjects inhaled lyso-PAF as a control.
  • Measurements included leukopenia, leukocytosis, minute ventilation, respiratory system resistance, systemic arterial pressure, PaO2, arterial-alveolar O2 gradient, and VA/Q mismatch parameters.

Main Results:

  • PAF inhalation induced immediate leukopenia followed by rebound leukocytosis.
  • PAF significantly increased minute ventilation and respiratory system resistance.
  • PAF caused a trend of decreased PaO2 and increased arterial-alveolar O2 gradient due to significant VA/Q mismatch.

Conclusions:

  • Inhaled PAF causes significant immediate VA/Q inequality and gas exchange impairment in healthy individuals.
  • These findings support the role of PAF as a critical mediator of inflammation in the human lung.