Home About us Contact
|
Home About us Contact | ||
|
|
||
Pulmonary Perfusion (pulmonary + perfusion)
Selected AbstractsCongenital lobar emphysema: Differential diagnosis and therapeutic approachPEDIATRICS INTERNATIONAL, Issue 5 2008Refik Ulku Abstract Background: Congenital lobar emphysema (CLE) is a rare anomaly of lung development that usually presents in the neonatal period with respirator distress and pulmonary lobar hyperinflation. It is commonly confused with pneumothorax. The aim of the present paper was to review the authors' experience in order to emphasize the importance of differential diagnosis with pneumothorax. Methods: Children with CLE treatment at Department of Thoracic Surgery, Dicle University School of Medicine, Turkey, between January 1993 and June 2004, were reviewed. Results: Ten children consisting of six boys and four girls (age range, 6 h,12 months) had CLE. Major presenting symptoms were tachypnea(n = 100%) and respiratory distress in (n = 80%). On chest radiograph, emphysema was seen in all patients, and shift-herniation to the opposite lung, atelectasis were observed. Computed tomography was performed in all patients, which indicated emphysema in the affected lobes in all cases. Pulmonary perfusion scan was performed in two patients, showing loss of perfusion in the affected lobe. The most common affected lobe was the left upper lobe (50%). In the present series, three patients were mistakenly diagnosed as pneumothorax and intercostal drains were inserted in the emergency department. Eight patients underwent lobectomy, and postoperative course was uneventful. Two patients were followed conservatively. Emphysema was detected in all pathological specimens. One patient was lost to follow up. Mean follow-up duration of all patients was 26.8 ± 29.24 months (range, 1,89 months). Conclusions: CLE is established on combined clinical, radiological and scintigraphic imaging. Surgical excision of the affected lobe is the appropriate treatment. Particularly, differential diagnosis should be made between CLE and pneumothorax. [source] Electrical impedence tomography and heterogeneity of pulmonary perfusion and ventilation in porcine acute lung injuryACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 10 2009A. FAGERBERG Background: The heterogeneity of pulmonary ventilation (V), perfusion (Q) and V/Q matching impairs gas exchange in an acute lung injury (ALI). This study investigated the feasibility of electrical impedance tomography (EIT) to assess the V/Q distribution and matching during an endotoxinaemic ALI in pigs. Methods: Mechanically ventilated, anaesthetised pigs (n=11, weight 30,36 kg) were studied during an infusion of endotoxin for 150 min. Impedance changes related to ventilation (ZV) and perfusion (ZQ) were monitored globally and bilaterally in four regions of interest (ROIs) of the EIT image. The distribution and ratio of ZV and ZQ were assessed. The alveolar,arterial oxygen difference, venous admixture, fractional alveolar dead space and functional residual capacity (FRC) were recorded, together with global and regional lung compliances and haemodynamic parameters. Values are mean±standard deviation (SD) and regression coefficients. Results: Endotoxinaemia increased the heterogeneity of ZQ but not ZV. Lung compliance progressively decreased with a ventral redistribution of ZV. A concomitant dorsal redistribution of ZQ resulted in mismatch of global (from ZV/ZQ 1.1±0.1 to 0.83±0.3) and notably dorsal (from ZV/ZQ 0.86±0.4 to 0.51±0.3) V and Q. Changes in global ZV/ZQ correlated with changes in the alveolar,arterial oxygen difference (r2=0.65, P<0.05), venous admixture (r2=0.66, P<0.05) and fractional alveolar dead space (r2=0.61, P<0.05). Decreased end-expiratory ZV correlated with decreased FRC (r2=0.74, P<0.05). Conclusions: EIT can be used to assess the heterogeneity of regional pulmonary ventilation and perfusion and V/Q matching during endotoxinaemic ALI, identifying pivotal pathophysiological changes. [source] Iloprost inhalation redistributes pulmonary perfusion and decreases arterial oxygenation in healthy volunteersACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 9 2009D. RIMEIKA Background: Previous studies have shown that ventilation,perfusion matching is improved in the prone as compared with that in the supine position. Regional differences in the regulation of vascular tone may explain this. We have recently demonstrated higher production of nitric oxide in dorsal compared with ventral human lung tissue. The purpose of the present study was to investigate regional differences in actions by another vasoactive mediator, namely prostacyclin. The effects on gas exchange and regional pulmonary perfusion in different body positions were investigated at increased prostacyclin levels by inhalation of a synthetic prostacyclin analogue and decreased prostacyclin levels by unselective cyclooxygenase (COX) inhibition. Methods: In 19 volunteers, regional pulmonary perfusion in the prone and supine position was assessed by single photon emission computed tomography using 99mTc macro-aggregated albumin before and after inhalation of iloprost, a stable prostacyclin analogue, or an intravenous infusion of a non-selective COX inhibitor, diclofenac. In addition, gas distribution was assessed in seven subjects using 99mTc-labelled ultra-fine carbon particles before and after iloprost inhalation in the supine position. Results: Iloprost inhalation decreased arterial PaO2 in both prone (from 14.2±0.5 to 11.7±1.7 kPa, P<0.01) and supine (from 13.7±1.4 to 10.9±2.1 kPa, P<0.01) positions. Iloprost inhalation redistributed lung perfusion from non-dependent to dependent lung regions in both prone and supine positions, while ventilation in the supine position was distributed in the opposite direction. No significant effects of non-selective COX inhibition were found in this study. Conclusions: Iloprost inhalation decreases arterial oxygenation and results in a more gravity-dependent pulmonary perfusion in both supine and prone positions in healthy humans. [source] Dynamic observation of pulmonary perfusion using continuous arterial spin-labeling in a pig modelJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 2 2001David A. Roberts MD Abstract The continuous arterial spin-labeling (CASL) method of perfusion MRI is used to observe pulmonary perfusion dynamically in an animal model. Specifically, a respiratory-triggered implementation of the CASL method is used with approximate spatial resolution of 0.9 × 1.8 × 5.0 mm (0.008 cc) and 2-minute temporal resolution. Perfusion MRI is performed dynamically during repeated balloon occlusion of a segmental pulmonary artery, as well as during pharmacological stimulation. A total of three Yorkshire pigs were studied. The results demonstrate the ability of the endogenous spin-labeling method to characterize the dynamic changes in pulmonary perfusion that occur during important physiological alterations. J. Magn. Reson. Imaging 2001;14:175,180. © 2001 Wiley-Liss, Inc. [source] Monitoring pulmonary perfusion by electrical impedance tomography: an evaluation in a pig modelACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 2 2009A. FAGERBERG Background: Electrical impedance tomography (EIT) is a non-invasive technique that generates images of impedance distribution. Changes in the pulmonary content of air and blood are major determinants of thoracic impedance. This study was designed to evaluate EIT in monitoring pulmonary perfusion in a wide range of cardiac output. Methods: Eight anaesthetised, mechanically ventilated pigs were fitted with a 16-electrode belt at the mid-thoracic level to generate EIT images that were analysed to determine pulse-synchronous systolic changes in impedance (,Zsys). Stroke volume (SV) was derived using a pulmonary artery catheter. Reductions in cardiac pre-load, and thus pulmonary perfusion, were induced either by inflating the balloon of a Fogarty catheter positioned in the inferior caval vein or by increasing the positive end-expiratory pressure (PEEP). All measurements were performed in a steady state during a short apnoea. Results: Pulse-synchronous changes in ,Zsys were easily discernable during apnoea. Balloon inflation reduced SV to 36% of the baseline, with a corresponding decrease in ,Zsys to 45% of baseline. PEEP reduced SV and ,Zsys to 52% and 44% of the baseline, respectively. Significant correlations between SV and ,Zsys were demonstrated during all measurements (,=0.62) as well as during balloon inflation (,=0.73) and increased PEEP (,=0.40). A Bland,Altman comparison of relative changes in SV and ,Zsys demonstrated a bias of ,7%, with 95% limits of agreement at ,51% and 36%. Conclusions: EIT provided beat-to-beat approximations of pulmonary perfusion that significantly correlated to a wide range of SV values achieved during both extra and intrapulmonary interventions to change cardiac output. [source] Elucidation of structure,function relationships in the lung: contributions from hyperpolarized 3helium MRICLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 6 2002Hans-Ulrich Kauczor Summary Magnetic resonance imaging (MRI) using hyperpolarized 3helium (He) gas as the source of signal provides new physiological insights into the structure,function relationships of the lung. Traditionally, lung morphology has been visualized by chest radiography and computed tomography, whereas lung function was assessed by using nuclear medicine. As all these techniques rely on ionizing radiation, MRI has some inherent advantages. 3He MRI is based on ,optical pumping' of the 3He gas which increases the nuclear spin polarization by four to five orders of magnitude translating into a massive gain in signal. Hyperpolarized 3He gas is administered as an inhaled ,contrast agent' and allows for selective visualization of airways and airspaces. Straightforward gas density images demonstrate the homogeneity of ventilation with high spatial resolution. In patients with lung diseases 3He MRI has shown a high sensitivity to depict ventilation defects. As 3He has some more exciting properties, a comprehensive four-step functional imaging protocol has been established. The dynamic distribution of ventilation during continuous breathing can be visualized after inhalation of a single breath of 3He gas using magnetic resonance (MR) sequences with high temporal resolution. Diffusion weighted 3He MRI provides a new measure for pulmonary microstructure because the degree of restriction of the Brownian motion of the 3He atoms reflects lung structure. Since the decay of 3He hyperpolarization is dependent on the ambient oxygen concentration, regional and temporal analysis of intrapulmonary pO2 becomes feasible. Thus, pulmonary perfusion, ventilation,/perfusion ratio and oxygen uptake can be indirectly assessed. Further research will determine the significance of the functional information with regard to physiology and patient management. [source] | ||||||||||