Effect of body positions on hemodynamics and gas exchange in anesthetized pigs shortly after pneumonectomy
ABSTRACT Positional changes are thought to affect hemodynamics, respiratory mechanics, and gas exchange after pneumonectomy. The objective of this study was to compare hemodynamic and respiratory parameters and gas exchange in different positions before and after pneumonectomy. Twenty pigs were anesthetized and mechanically ventilated. Seven received right-side pneumonectomy, seven received left-side pneumonectomy, and six were anesthetized but did not receive surgery and served as controls. Hemodynamic and respiratory parameters and blood gas values were measured in different positions (supine and right and left lateral decubitus). Minute mechanical ventilation was controlled throughout. Pneumonectomy resulted in significant reductions in MAP, accompanied by significant decreases in cardiac index, stroke volume index, global ejection fraction, and global end-diastolic volume index. Mean pulmonary arterial pressure and pulmonary vascular resistance index increased. PaCO2, airway resistance, and peak airway pressure increased, whereas PaO2 and lung compliance decreased. Hemodynamic and respiratory parameters and gas exchange were also significantly affected by changes in position with pneumonectomy. Mean arterial pressure, cardiac index, stroke volume index, global ejection fraction, and global end-diastolic volume index were significantly lower in the supine than in the right or left lateral decubitus position. PaO2 was significantly higher in a lateral position, with the remaining lung uppermost. Our findings suggest that avoiding the supine positioning after pneumonectomy may facilitate improvements in hemodynamics and a decreased risk of hypoxemia. The optimal position for gas exchange after pneumonectomy is a lateral position, with the remaining lung in the uppermost position.
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ABSTRACT: Electrocardiographic (ECG) changes accompanying lung resection have not been well investigated previously in a large controlled series of human adults. Thus, our current investigation was undertaken for a better understanding of the ECG changes associated with lung resection. Medical records of 117 patients who underwent lung resection (segmentectomy, lobectomy, or pneumonectomy) were reviewed. Their clinical course and ECGs were compared during early, intermediate and late postoperative course (<1month, 1month to 1year and >1year post-op respectively). Patients in the acute postoperative phase had higher heart rate, increased maximum P-duration and P-dispersion, increased incidence of atrial arrhythmias and frequent ST-T changes. P-vector and QRS-vector were significantly affected after the lung resections; the correlation being most consistent between the anatomical displacements and the QRS-vector in the majority of patients. The axial shifts also demonstrated a characteristic temporal relationship after left pneumonectomy (a leftward deviation in the acute, normal or slight rightward deviation in the intermediate and a rightward deviation in the late postoperative course). The precordial R/S transition is often affected due to the mediastinal shifts and the ECGs in patients after left lung resection may simulate acute anteroseptal myocardial infarction due to a delayed R/S transition. The understanding and recognition of the expected ECG findings after lung resection are imperative to avoid confusing these changes with other acute cardiopulmonary events which would prevent unnecessary further investigational work-up. These ECG changes are often dynamic and may bear a temporal relationship to the dynamic post-surgical changes in the thoracic anatomy.Journal of electrocardiology 07/2013; 46(6). DOI:10.1016/j.jelectrocard.2013.05.140 · 1.36 Impact Factor