Changes In Pulmonary Pathophysiology Of Small Area Pulmonary Embolism On Porcine Experiment

Background and Objective: Acute pulmonary embolism is a major cause of death associated with heart disease (40%), cancer (35%), pregnancy and delivery (20%), surgery, injury and long-term lying in bed, and it may also occur after long-distance air travel. The incidence of pulmonary embolism in the foreign countries is very high and the fatality of pulmonary embolism ranked third highest in angiocardiopathy compare with coronary artery disease and apoplexy. This study analyzed the changes of pathophysiology happened on swine after we made the models of small area of pulmonary embolism.Material and Methods: 24 Swedish domestic pigs with a mean weight of 40 kg (35~45kg) were included randomly in this study. 18 pigs were classified as the experimental group and 6 as the control group. Anesthesia was induced with an intramuscular injection of Xylazine (4 mg/kg) and Ketamine (30 mg/kg). Atropine (0.015 mg/kg) and Sodium thiopental (5~8 mg/kg) were given intravenously before tracheotomy. Anesthesia and muscular paralysis were maintained with a continuous infusion of 10 ml/h of a NaCl (0.9%) solution containing Ketamine (16mg/ml) and Pancuronium (0.6 mg/ml). Then endotracheal tube, was inserted and connected to a Servo Ventilator, using pressure-regulated (max 30cmH2O = 23mmHg) and volume-controlled IPPV, with a tidal volume of 15 ml/kg body weight, 20 breaths/min, a FiO2 of 0.5 and a PEEP of 5 cmH2O (= 6mmHg). The end-tidal CO2 was measured by CO2SMO Plus Respiratory Profile Monitor. Three catheters for blood pressure measurements and blood sampling were introduced via direct puncture of the right carotid artery and the right internal jugular vein. The left thoracotomy and pericardiotomy were proformed. The left inferior pulmonary vein (LIPV), left inferior pulmonary artery (LIPA) and pulmonary artery (PA) were separated respectively. One wide ligature was put around LIPA. Blood flow probes were put around PA and LIPV. Catheters were put in PA and LIPV for blood pressure measurements and blood sampling. The LIPA of the experimental group was ligated and released 30 min later. The changes of mean arterial pressure (MAP), central venous pressure (CVP), pulmonary arterial pressure (PAP), pulmonary arterial flow (PAF), left inferior pulmonary venous flow (LIPVF) and blood gas results were recorded. We didn't block the LIPA of the control group but only recorded the data. Data were expressed as mean±SEM. Statistical analyses were conducted with SPSS 13.0. A P value less than 0.05 was considered statistically significant.Results: PAP increased (P<0.05) after LIPA was blocked, PAF decreased (P<0.05), MAP has no significant change (P>0.05), pCO2 of blood gas increased (P<0.05), pO2 decreased (P<0.05), Lac increased (P<0.05). Every outcome measures recovered to base situation progressively after the block at LIPA was released.Conclusions: Small area was made of pulmonary embolism is harmless if timely monitoring and treatment.