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Pulmonary Ventilation (pulmonary + ventilation)

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Medical Sciences100%

Selected Abstracts

Electrical impedence tomography and heterogeneity of pulmonary perfusion and ventilation in porcine acute lung injury

ACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 10 2009
A. 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]

Oxygen-enhanced MR imaging of mice lungs

MAGNETIC RESONANCE IN MEDICINE, Issue 6 2008
K.N. Watt
Abstract Inhaled molecular oxygen has been widely used in humans to evaluate pulmonary ventilation using MRI. MR imaging has recently played a greater role in examining the morphologic and physiologic characteristics of mouse models of lung disease where structural changes are highly correlated to abnormalities in respiratory function. The motivation of this work is to develop oxygen-enhanced MR imaging for mice. Conventional human MR techniques cannot be directly applied to mouse imaging due to smaller dimensions and faster cardiac and respiratory physiology. This study examines the development of oxygen-enhanced MR as a noninvasive tool to assess regional ventilation in spontaneously breathing mice. An optimized cardiac-triggered, respiratory-gated fast spin-echo imaging sequence was developed to address demands of attaining adequate signal from the parenchyma, maintaining practical acquisition times, and compensating for rapid physiological motion. On average, a 20% T1 -shortening effect was observed in mice breathing 100% oxygen as compared to air. The effect of ventilation was shown as a significant signal intensity increase of 11% to 16% in the mouse parenchyma with 100% oxygen inhalation. This work demonstrates that adequate contrast and resolution can be achieved using oxygen-enhanced MR to visualize ventilation, providing an effective technique to study ventilation defects in mice. Magn Reson Med, 2008. © 2008 Wiley-Liss, Inc. [source]

Usefulness of a program of hospital-supervised physical training in patients with cystic fibrosis

PEDIATRIC PULMONOLOGY, Issue 2 2004
Attilio Turchetta MD
Abstract Exercise is an important part of normal childhood, but the ability to exercise may be impaired in chronic lung diseases such as cystic fibrosis (CF). Improving exercise performance by training is very attractive. The aim of the present study was the evaluation of the effects of a physical aerobic training program, performed in the Children's Hospital and Research Institute "Bambino Gesł" (Rome, Italy) in outpatient CF children, supervised by a physician. Twelve patients (mean forced expiratory flow in 1 sec (FEV1), 71%), age range 12,24 years (16.7 ± 4.4 years), were enrolled. They performed a maximal exercise stress test on the treadmill (modified Bruce protocol) with breath-by-breath determination of oxygen consumption (VO2) to maximum at end-exercise; we measured time of exercise (TE), maximal heart rate (Hrmax) in beats per minute (bpm), and maximal systolic blood pressure (SBPm) in mmHg. The program consisted of 12 weeks of training twice a week. Each training session consisted of walking or running on the treadmill for 30 min at the speed that allowed the child to attain 60% of the maximal heart rate obtained during a baseline stress test for 4 weeks, 70% in the following 4 weeks, and 80% in the last 4 weeks, under strict medical supervision. HR was continously monitored. There was no change in FEV1 and forced vital capacity after the treatment period. Hrmax and SBPm also remained the same (P,=,0.37 and P,=,0.25, respectively). There was a significant increase in TE (P,<,0.002), VO2, VO2/kg, and pulmonary ventilation (VE) (P,<,0.0001, P,<,0.001, and P,<,0.001, respectively). This pilot study showed that a simple training program improves short-term cardiopulmonary fitness in children with CF. Further studies with a larger sample and for a more prolonged time are necessary to assess if sport can have a long-term effect on lung function or survival in CF patients. Pediatr Pulmonol. 2004; 38:115,118. © 2004 Wiley-Liss, Inc. [source]