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: Background Right ventricular (RV) volume and function are important diagnostic and prognostic factors in dogs with primary or secondary right-sided heart failure. The complex shape of the right ventricle and its retrosternal position make the quantification of its volume difficult. For that reason, only few studies exist, which deal with the determination of RV volume parameters. In human medicine cardiac magnetic resonance imaging (CMRI) is considered to be the reference technique for RV volumetric measurement (Nat Rev Cardiol 7(10):551-563, 2010), but cardiac computed tomography (CCT) and three-dimensional echocardiography (3DE) are other non-invasive methods feasible for RV volume quantification. The purpose of this study was the comparison of 3DE and CCT with CMRI, the gold standard for RV volumetric quantification.Results3DE showed significant lower and CCT significant higher right ventricular volumes than CMRI. Both techniques showed very good correlations (R¿>¿0.8) with CMRI for the volumetric parameters end-diastolic volume (EDV) and end-systolic volume (ESV). Ejection fraction (EF) and stroke volume (SV) were not different when considering CCT and CMRI, whereas 3DE showed a significant higher EF and lower SV than CMRI. The 3DE values showed excellent intra-observer variability (<3%) and still acceptable inter-observer variability (<13%).ConclusionCCT provides an accurate image quality of the right ventricle with comparable results to the reference method CMRI. CCT overestimates the RV volumes; therefore, it is not an interchangeable method, having the disadvantage as well of needing general anaesthesia. 3DE underestimated the RV-Volumes, which could be explained by the worse image resolution. The excellent correlation between the methods indicates a close relationship between 3DE and CMRI although not directly comparable. 3DE is a promising technique for RV volumetric quantification, but further studies in awake dogs and dogs with heart disease are necessary to evaluate its usefulness in veterinary cardiology.BMC Veterinary Research 10/2014; 10(1):242. DOI:10.1186/s12917-014-0242-3 · 1.74 Impact Factor
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ABSTRACT: Thoracotomy is a common procedure. However, thoracotomy leads to lung atelectasis and deteriorates pulmonary gas exchange in operated side. Therefore, different positions with operated side lowermost or uppermost may lead to different gas exchange after thoracotomy. Besides, PEEP (positive end-expiratory pressure) influence lung atelectasis and should influence gas exchange. The purpose of this study was to determine the physiological changes in different positions after thoracotomy. In addition, we also studied the influence of PEEP to positional effects after thoracotomy. There were eight pigs in each group. Group I received left thoracotomy with zero end-expiratory pressure (ZEEP), and group II with PEEP; group III received right thoracotomy with ZEEP and group IV with PEEP. We changed positions to supine, LLD (left lateral decubitus) and RLD (right lateral decubitus) in random order after thoracotomy. PaO2 was decreased after thoracotomy and higher in RLD after left thoracotomy and in LLD after right thoracotomy. PaO2 in groups II and IV was higher than in groups I and III if with the same position. In group I and III, PaCO2 was increased after thoracotomy and was higher in LLD after left thoracotomy and in RLD after right thoracotomy. In groups II and IV, there were no PaCO2 changes in different positions after thoracotomy. Lung compliance (Crs) was decreased after thoracotomy in groups I and III and highest in RLD after left thoracotomy and in LLD after right thoracotomy. In groups II and IV, there were no changes in Crs regardless of the different positions. There were significant changes with regards to pulmonary gas exchange, hemodynamics and Crs after thoracotomy. The best position was non-operated lung lowermost Applying PEEP attenuates the positional effects.Annals of Thoracic Medicine 03/2014; 9(2):112-119. DOI:10.4103/1817-1737.128860 · 1.34 Impact Factor
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ABSTRACT: Background and aims: The use of fractional exhaled nitric oxide (FeNO) has been suggested as a quantitative marker for pulmonary arterial hypertension (PAH) in humans. To further characterize FeNO in PAH we investigated this marker in a rodent model. As there is no standardized technique for FeNO measurement in animals, we intended to reduce measuring errors and confounders of an existing published method by mathematical modification and tested its applicability in an NO-regulating therapy concept of PAH. Methods: Thirty-three male Sprague-Dawley rats underwent unilateral pneumonectomy and monocrotaline (P/MCT) injection and were observed for 49 days. A telemetric catheter was introduced into the left pulmonary artery to continuously record mean pulmonary arterial pressure (mPAP) and FeNO was assessed. After 35 days, animals were randomised to receive either oral L-arginine (300mg/kg) in combination with tetrahydrobiopterin (20mg/kg) therapy (n=12) or vehicle (n=11) daily over a period of 14 days. Results: Mean PAP at baseline was 17.19±9.62mmHg, which increased to 53.1±10.63mmHg 28 days after monocrotaline exposure (p<0.001). Using the modified technique there was an inverse correlation between exhaled NO and pulmonary pressures before (r=-0.366, p=0.043) and after MCT (r=-0.363, p=0.038) as well as after therapy administration (r=-0.657, p=0.02). Conclusion: Our modified technique proved robust in a rodent model, since valid and reproducible data were gained and showed an inverse correlation between exhaled NO and mPAP, while the existing method did not.AJP Lung Cellular and Molecular Physiology 07/2013; 305(7). DOI:10.1152/ajplung.00087.2013 · 4.04 Impact Factor