Effects Of Mechanical Ventilation On Patients With Acute Myocardial Infarction Accompanied With Pulmonary Edema

Noninvasive mechanical ventilation has been used to treat acute pulmonary edema,there has been a great progress and recognition for the treatment,but some studies found that noninvasive positive-pressure ventilation cannot be used for treating acute pulmonary edema due to acute myocardial infarction.Now the treatment to acute pulmonary edema due to acute myocardial infarction is still controversial.Objective1) To evaluate the physiologic response of positive-pressure mechanical ventilation on acute pulmonary edema due to acute myocardial infarction by observing vital signs and effect of positive airway pressure on valves hemodynamics,especially the relationship of blood flow velocity and respiratory phases.2) To study the values changes of Brain natriuretic peptide(BNP) and hypersensitive C- reactive protein(hs-CRP) during mechanical ventilation treatment.Methods1) 62 patients with an acute myocardial infarction complicated with pulmonary edema were studied.All patients gave written informed consent before participating. According to APACHEâ…¢score,all patients had acute pulmonary edema and whose condition had not improved with aggressive medical therapy and who required mechanical ventilation.After using mechanical ventilation,all vital signs were observed.2) Using color echocardiographic and pulse wave Doppler echocardiogram(PWDE) to record blood flow velocity at mitral valve,tricuspid valve,pulmonary valve,and aortic valve orifice under positive- pressure mechanical ventilation.3) Using laboratory procedures to analyze the value of BNP and using nephelometry to evaluate hs-CRP value.Results1) With ventilation treatment,all patients showed significant improvement. Noninvasive ventilation was effective in improving gas exchange and hypoxia,and did not observe rapid hemodynamic changes and aggravation of ischemia.2) Blood flow rate reached to the highest level in artery valve and mitral valve at positive end-inhalation pressure and decrease at end-expiratory,which means that left ventricle output was highest at end-inhalation point in each respiration cycle and same as in mitral valve.The highest point of E wave appeared at end-inhalation.The results showed that compared to expiratory phase,left cardiac function was improved.3) Blood BNP and hs-CRP level were affected by heart failure;cardiac dysfunction indicated a higher risk of death.BNP and hs-CRP level were powerful predictors.It provided prognostic information beyond clinical risk factors,comparing to BNP level before undergoing mechanical ventilation(P =0.000).Therefore,BNP and hs-CRP are valuable indicators to determine prognostic information.Conclusion1) Noninvasive positive-pressure ventilation is a safe and effective means of improving gas exchange in patients with acute pulmonary edema.It has been approved that ventilation treatment can improve oxygenation and cardio function,but the treatment to acute pulmonary edema due to acute myocardial infarction is still controversial. Therefore,not every patient with left ventricular acute myocardial infarction required ventilation treatment.It is the one of the most efficient ways,but timing and contraindication are the keys.2) The blood flow rate reaches to the highest level in artery valve at positive end-inhalation pressure and decrease at end-expiratory.Compared to expiratory phase, left cardiac function is improved at inhalation phase.Right ventricular filling increase is one of the most important reasons to improve pump function of left ventricle during an inhalation phase.3) BNP and hs-CRP levels indicate cardiac function and are proved as reliable indicators of additional prognostic power.