Elastic properties of the lung and the chest wall in young and adult healthy pigs (original) (raw)
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Intensive Care Medicine, 1999
The elastic pressure-volume (P/V) curve is becoming an established tool in the care of patients with critical respiratory failure [1, 2, 3, 4, 5]. In spite of the extensive literature on elastic lung properties in healthy and diseased mammals and man, a full understanding of factors influencing the P/V curve is lacking. New phenomena are still being found, like an important dependence upon the expiratory pressure from which the insufflation starts [6]. Few studies describe respiratory mechanics in pigs [7, 8, 9]. These studies do not cover the entire P/V curve and do not analyse factors which contribute to non-linear features. The pig is used for models of acute lung injury. As a reference, therefore, an increased knowledge
2014
Objectives: To determine the role of the endinspiratory transpulmonary pressure as an indicator of the lung stress in the disorder of chest wall mechanics, in pig model. Design: Experimental study. Setting: Department of Surgery and Radiology, Veterinary Medicine, Bogor Agricultural Institute. Subjects: Nine healthy mixed breed domestic piglets were divided into 2 groups: intervention/splinted chest wall (n=5) and control (n=4). Intervention: This study had approval from Animal Care and Use Committee. The care and handling animal were accorded with National Institute of Health guideline. All of animals were anesthetized, muscle paralyzed and bronchial lavage with warm saline, in supine position. Both group were mechanically ventilated and underwent lung recruitment using incremental-decremental technique. Chest wall splinting was conducted in intervention group while the control group did not. Measurement and Main Results: Transpulmonary pressures calculated after measure the eso. p...
Journal of Clinical Medicine, 2021
The effects of a moderately elevated intra-abdominal pressure (IAP) on lung mechanics in acute respiratory distress syndrome (ARDS) have still not been fully analyzed. Moreover, the optimal positive end-expiratory pressure (PEEP) in elevated IAP and ARDS is unclear. In this paper, 18 pigs under general anesthesia received a double hit lung injury. After saline lung lavage and 2 h of injurious mechanical ventilation to induce an acute lung injury (ALI), an intra-abdominal balloon was filled until an IAP of 10 mmHg was generated. Animals were randomly assigned to one of three groups (group A = PEEP 5, B = PEEP 10 and C = PEEP 15 cmH2O) and ventilated for 6 h. We measured end-expiratory lung volume (EELV) per kg bodyweight, driving pressure (ΔP), transpulmonary pressure (ΔPL), static lung compliance (Cstat), oxygenation (P/F ratio) and cardiac index (CI). In group A, we found increases in ΔP (22 ± 1 vs. 28 ± 2 cmH2O; p = 0.006) and ΔPL (16 ± 1 vs. 22 ± 2 cmH2O; p = 0.007), with no chan...
Critical care (London, England), 2006
Atelectasis and distal airway closure are common clinical entities of general anaesthesia. These two phenomena are expected to reduce the ventilation of dependent lung regions and represent major causes of arterial oxygenation impairment in anaesthetic conditions. In the present study, the behavior of the elastance of the respiratory system (Ers), as well as the lung aeration assessed by CT-scan, was evaluated during a descendent positive end-expiratory pressure (PEEP) titration. This work sought to evaluate the potential usefulness of the Ers monitoring to set the PEEP in order to prevent tidal recruitment and hyperinflation of healthy lungs under general anaesthesia. PEEP titration (from 16 to 0 cmH2O, with a tidal volume of 8 ml/kg) was performed, and at each PEEP, helical CT-scans were obtained during end-expiratory and end-inspiratory pauses in six healthy, anaesthetized and paralyzed piglets. The distribution of lung compartments (hyperinflated (HA), normally- (NA), poorly- (P...
Physiological reports, 2016
Heterogeneity in regional end expiratory lung volume (EELV) may lead to variations in regional strain (ε). High ε levels have been associated with ventilator-associated lung injury (VALI). While both whole lung and regional EELV may be affected by changes in positive end-expiratory pressure (PEEP), regional variations are not revealed by conventional respiratory system measurements. Differential rates of deflation of adjacent lung units due to regional variation in expiratory time constants (τE) may create localized regions of ε that are significantly greater than implied by whole lung measures. We used functional respiratory imaging (FRI) in an ex vivo porcine lung model to: (i) demonstrate that computed tomography (CT)-based imaging studies can be used to assess global and regional values of ε and τE and, (ii) demonstrate that the manipulation of PEEP will cause measurable changes in total and regional ε and τE values. Our study provides three insights into lung mechanics. First, ...
Acta Cirurgica Brasileira, 2008
Purpose: To evaluate the effects of alveolar recruitment based on mean airway pressure (MAP) on pig lungs submitted to thoracotomy through blood gas exchange and hemodynamic parameters. Methods: Twelve pigs weighting approximately 25Kg were intubated and ventilated on volume controlled ventilation (tidal volume 10ml/Kg, respiratory rate 16min, FiO 2 1.0, inspiratory:expiratory ratio 1:2, PEEP 5cmH 2 O). The animals were then randomized into two groups: control and left lateral thoracotomy. The PEEP was increased at each 15-minute intervals to reach a MAP of 15, 20 and 25cmH 2 O, respectively. Hemodynamic, gas exchange and respiratory mechanic data were measured immediately before each PEEP change. Results: There were no significant differences between both groups in all parameters analyzed (P=1.0). The PaO 2 , PaCO 2 , MAP, PAP and plateau pressure were significantly worse at MAP of 25cmH 2 O, when compared with the other values of MAP (P=0.001, P=0.039, P=0.001, P=0.016 e P=0.027, respectively). The best pulmonary performance according to the analyzed parameters was observed at MAP of 20cmH 2 O. Conclusion: PEEP adjusted to MAP of 20cmH 2 O resulted in best arterial oxygenation, without compromising the venous return, as opposed to MAP of 25cmH 2 O, which caused deterioration of gas exchange, hemodynamics and respiratory mechanic.
Critical Care Medicine, 2012
Rationale: In presence of increased chest wall elastance the airway pressure does not reflect the lung-distending (transpulmonary) pressure. Objective: to compare the physiological effects of a conventional open lung approach titrated for an end-inspiratory airway opening plateau pressure (30 cmH 2 O) with a transpulmonary open lung approach titrated for a elastance-derived end-inspiratory plateau transpulmonary pressure (26 cmH 2 O), in a pig model of ARDS (HCl inhalation) and reversible chest wall mechanical impairment (chest wall and abdomen restriction). Methods: in eight pigs physiological parameters and computed tomography were recorded under three conditions: 1) conventional open lung approach, normal chest wall; 2) conventional open lung approach, stiff chest wall and 3) transpulmonary open lung approach, stiff chest wall. Measurements and Main Results: as compared with the normal chest wall condition, at endexpiration non-aerated lung tissue weight increased by 116 ± 68 % during the conventional open lung approach and by 28 ± 41 % during the transpulmonary open lung approach (p < 0.01) whereas cardiac output decreased by 27 ± 19 % and by 22 ± 14 %, respectively (p = NS). Conclusion: In this model, the end-inspiratory transpulmonary open lung approach minimized the impact of chest wall stiffening on alveolar recruitment without causing hemodynamic impairment.