Near-fatal pulmonary embolism in an experimental model: hemodynamic, gasometric and capnographic variables

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Introduction: Experimental studies on pulmonary embolism (PE) are usually performed under mechanical ventilation. Most patients with suspicion of PE enter the Emergency Services in spontaneous breathing and environmental air. Thus, under these conditions, measurements. of hemodynamic, gasometric and capnographic variables contribute largely to a more specific comprehension of cardiopulmonary and gasometric alterations in the acute phase of the disease. Studies which evaluated animals under conditions are lacking. Objective: This study aimed to submit animals under spontaneous ventilation and without supplemental oxygen to PE. Methods: PE was induced in six pigs using autologous blood clots, and cardiorespiratory and gasometric records were performed before and after PE. The values of "near fatal" mean pulmonary arterial pressure (MPAP) were previously determined. Results: The presence of obstructive shock could be evidenced by increased MPAP (from 17.8 +/- 3.5 to 41.7 +/--3.3 mmHg) (P<0.0001) and decreased cardiac output (from 4.9 +/- 1.0 to 2.7 +/- 1.0 L/min) (P<0.003). Consequently, metabolic acidosis occurred (Lac art) (from 2.4 +/--0.6 to 5.7 +/- 1.8 mmol/L) (P<0.0001). It was observed hypoxemia (from 73.5 +/- 12.7 to 40.3 +/- 4.6 mmHg) (P<0.0001); however, PaCO(2) did not vary (from 44.9 +/- 4.4 to 48.2 +/- 6.0 mmHg) (NS). There were significant increases in both P(a-et)CO(2) (from 4.8 +/- 2.8 to 37.2 +/- 5.8 mmHg) and P(A-a)O(2) (from 8.2 +/- 8.9 to 37.2 +/- 10.3 mmHg) (both P<0.0001). There was also a significant increase in the total alveolar minute volume (from 4.0 +/- 0.9 to 10.6 +/- 2.9 L/min) (P