Mecanismos que interferem no intercambio gasoso no tromboembolismo pulmonar experimental / Mechanisms underlying gas exchange alterations in an experimental model of pulmonary embolism

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

The literature broadly approaches the mechanisms responsible for the genesis of the hypoxemia in pulmonary embolism (PE). The aim of this study is to analyze the ventilation/perfusion ratio, which contributed to the hypoxemia in PE by analyzing blood gases and volumetric capnography in a model of experimental acute PE. Pulmonary embolization with autologous blood clots was carried out in seven pigs weighing 24.00±0.6Kg, anesthetized and mechanically ventilated. A significant reduction in the oxygen partial pressures was observed in both, the arterial blood and alveolar air. The effective alveolar ventilation exhibited a significant reduction consistent with the fall in the alveolar gas volume that effectively participated in gas exchange. The relation between the alveolar ventilation that effectively participated in gas exchange and cardiac output (V?Aeff/Q? ratio) also presented a significant reduction after embolization. The carbon dioxide partial pressure increased significantly in the arterial blood (PaCO2), but decreased significantly in the exhaled air at the end of the respiratory cycle (PetCO2). PetCO2 returned to baseline values forty minutes after embolism. The arterial to alveolar carbon dioxide gradient (P(a-et)CO2), increased significantly, as well as the calculated alveolar and physiological dead spaces. We conclude, based on our data, that the severe arterial hypoxemia observed in this experimental model may be attributed to the reduction of the effective alveolar ventilation ratio (V?Aeff/Q?). We were also able to demonstrate that V?Aeff/Q? progressively improves after embolization, a fact attributed to the lysis of thromby or by alveolar ventilation redistribution induced by hypocapnic bronchoconstriction

ASSUNTO(S)

perfusion mimatching pulmonary gas exchange desequilibrio ventilação - perfusão ventilação pulmonar ventilation perfusão - ventilação pulmonary ventilation perfusion ventilation troca gasosa pulmonar

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