Measuring end-expiratory lung volume and pulmonary mechanics to detect early lung function impairment in rabbits

Habre, Walid; Scalfaro, Piétro; Schütz, Nathalie; Stucki, Pascal; Peták, Ferenc

doi:10.1016/j.resp.2005.07.003

Cited by 12 publications

(7 citation statements)

References 33 publications

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“…In agreement with previous findings, a monotonous decrease in the airway resistance was observed in the present study and can be attributed to the enlargement of the overall bronchial diameter with lung expansion (10,14,18,29,34). At low to moderate PEEP levels, increasing PEEP otherwise causes an initial decrease in the viscoelastic tissue parameters because of lung recruitment, followed by an increase with excessive stretching of the fully recruited lung tissue (18,33,34). The changes in G and H derived from Z rs and Z L are in accordance with earlier findings in the low to moderate PEEP range, which is routinely applied for these animal species (18,34).…”

Section: Discussionsupporting

confidence: 94%

Different contributions from lungs and chest wall to respiratory mechanics in mice, rats, and rabbits

Südy

Fodor

Rocha

et al. 2019

Journal of Applied Physiology

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Changes in lung mechanics are frequently inferred from intact-chest measures of total respiratory system mechanics without consideration of the chest wall contribution. The participation of lungs and chest wall in respiratory mechanics has not been evaluated systematically in small animals commonly used in respiratory research. Thus, we compared these contributions in intact-chest mice, rats, and rabbits and further characterized the influence of positive end-expiratory pressure (PEEP). Forced oscillation technique was applied to anesthetized mechanically ventilated healthy animals to obtain total respiratory system impedance (Zrs) at 0, 3, and 6 cmH2O PEEP levels. Esophageal pressure was measured by a catheter-tip micromanometer to separate Zrs into pulmonary (ZL) and chest wall (Zcw) components. A model containing a frequency-independent Newtonian resistance (RN), inertance, and a constant-phase tissue damping (G) and elastance (H) was fitted to Zrs, ZL, and Zcw spectra. The contribution of Zcw to RN was negligible in all species and PEEP levels studied. However, the participation of Zcw in G and H was significant in all species and increased significantly with increasing PEEP and animal size (rabbit > rat > mice). Even in mice, the chest wall contribution to G and H was still considerable, reaching 47.0 ± 4.0(SE)% and 32.9 ± 5.9% for G and H, respectively. These findings demonstrate that airway parameters can be assessed from respiratory system mechanical measurements. However, the contribution from the chest wall should be considered when intact-chest measurements are used to estimate lung parenchymal mechanics in small laboratory models (even in mice), particularly at elevated PEEP levels. NEW & NOTEWORTHY In species commonly used in respiratory research (rabbits, rats, mice), esophageal pressure-based estimates revealed negligible contribution from the chest wall to the Newtonian resistance. Conversely, chest wall participation in the viscoelastic tissue mechanical parameters increased with body size (rabbit > rat > mice) and positive end-expiratory pressure, with contribution varying between 30 and 50%, even in mice. These findings demonstrate the potential biasing effects of the chest wall when lung tissue mechanics are inferred from intact-chest measurements in small laboratory animals.

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Section: Discussionsupporting

confidence: 94%

Different contributions from lungs and chest wall to respiratory mechanics in mice, rats, and rabbits

Südy

Fodor

Rocha

et al. 2019

Journal of Applied Physiology

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“…The results obtained in the present study suggest that this parameter is less sensitive than FRC and LCI for detecting mild regional ventilation defects in spontaneously breathing children. This finding is in line with previous results comparing the sensitivity of the two techniques in detecting adverse changes in the lung periphery 26 .…”

Section: It Has Been Well Established That General Anaesthesia Promotsupporting

confidence: 93%

High inspired oxygen fraction impairs lung volume and ventilation heterogeneity in healthy children: a double-blind randomised controlled trial

Grandville

Peták

Albu

et al. 2019

British Journal of Anaesthesia

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Background: Although high inspired oxygen fraction (FiO 2) is common practice in pediatric anaesthesia, there is lack of evidence for affects on postoperative lung function. Therefore, we compared postoperative changes in lung volume, ventilation heterogeneity and respiratory mechanics while ventilating anaesthetised children with low or high FiO 2. Methods: In a double-blinded, randomized, controlled trial, children scheduled for elective surgery were randomly assigned 100% FiO 2 (Group H) or 80% FiO 2 (Group L) during anaesthesia induction and emergence, while anaesthesia was maintained with either FiO 2 of 80% (Group H) or 35% (Group L). During spontaneous breathing, we measured functional residual capacity (FRC) and lung clearance index (LCI) by multiple-breath nitrogen washout, airway resistance and respiratory tissue elastance by forced oscillations preoperatively (M1), after discharge from the recovery room (M2) and at day 1 postoperatively (M3). Secondary outcomes were the occurrence of respiratory complications, post-operative nausea and vomiting and surgical site infection at 30 days postoperatively. Results: FRC decreased in Group H at M2 (-14.7% [-21.0,-8.3] 95% CI, p=0.008) but normalized at M3. Ventilation inhomogeneity (LCI) increased in both groups at M2 but remained elevated only in Group H at M3 (6.3% [-0.3, 12.9%], p=0.023). No differences in respiratory mechanical parameters or in secondary outcomes were observed. Conclusions: High FiO 2 decreases lung volume in the immediate postoperative period with long-lasting enhancement in lung heterogeneity. This result, in addition to the wellestablished harmful effects of hyperoxia, supports the avoidance of high FiO 2 during anaesthesia management of children with normal lungs.

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“…This was manifested both in the excellent correlations between EELV MBW,He and EELV CT (Figure 4) and the good agreement (Figure 5). The importance of this finding stems from the fact that multiple breath washout technique by using ultrasonic flow meter has been applied commonly in experimental [6,10,17,20] and clinical studies [2,21-26]. However, the relationship of EELV MBW,He obtained by this approach was not related to that obtained by using a reference method in patients with acute lung injury based on CT imaging [7], and the validity of this variable has not been evaluated.…”

Section: Discussionmentioning

confidence: 99%

“…A technique using multiple-breath wash-in/wash-out maneuvers with helium (He) as tracer gas was used to measure EELV MBW,He , as detailed previously [1,10]. Briefly, an ultrasonic flow meter (Spiroson Scientific; ECO Medics AG, Dürnten, Switzerland) was instrumented between the endotracheal tube connector and the ventilator circuit to assess changes in molar mass of the respiratory gas.…”

Section: Methodsmentioning

confidence: 99%

Lung volume assessments in normal and surfactant depleted lungs: agreement between bedside techniques and CT imaging

et al. 2014

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BackgroundBedside assessment of lung volume in clinical practice is crucial to adapt ventilation strategy. We compared bedside measures of lung volume by helium multiple-breath washout technique (EELVMBW,He) and effective lung volume based on capnodynamics (ELV) to those assessed from spiral chest CT scans (EELVCT) under different PEEP levels in control and surfactant-depleted lungs.MethodsLung volume was assessed in anaesthetized mechanically ventilated rabbits successively by measuring i) ELV by analyzing CO2 elimination traces during the application of periods of 5 consecutive alterations in inspiratory/expiratory ratio (1:2 to 1.5:1), ii) measuring EELVMBW,He by using helium as a tracer gas, and iii) EELVCT from CT scan images by computing the normalized lung density. All measurements were performed at PEEP of 0, 3 and 9 cmH2O in random order under control condition and following surfactant depletion by whole lung lavage.ResultsVariables obtained with all techniques followed sensitively the lung volume changes with PEEP. Excellent correlation and close agreement was observed between EELVMBW,He and EELVCT (r = 0.93, p < 0.0001). ELV overestimated EELVMBW,He and EELVCT in normal lungs, whereas this difference was not evidenced following surfactant depletion. These findings resulted in somewhat diminished but still significant correlations between ELV and EELVCT (r = 0.58, p < 0.001) or EELVMBW,He (0.76, p < 0.001) and moderate agreements.ConclusionsLung volume assessed with bedside techniques allow the monitoring of the changes in the lung aeration with PEEP both in normal lungs and in a model of acute lung injury. Under stable pulmonary haemodynamic condition, ELV allows continuous lung volume monitoring, whereas EELVMBW,He offers a more accurate estimation, but intermittently.

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Measuring end-expiratory lung volume and pulmonary mechanics to detect early lung function impairment in rabbits

Cited by 12 publications

References 33 publications

Different contributions from lungs and chest wall to respiratory mechanics in mice, rats, and rabbits

Different contributions from lungs and chest wall to respiratory mechanics in mice, rats, and rabbits

High inspired oxygen fraction impairs lung volume and ventilation heterogeneity in healthy children: a double-blind randomised controlled trial

Lung volume assessments in normal and surfactant depleted lungs: agreement between bedside techniques and CT imaging

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