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Gedeon, Andras; Krill, Paul; Österlund, Barbro

doi:10.1023/a:1021232624767

Cited by 25 publications

(3 citation statements)

References 17 publications

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“…Static lung volume, such as the end-expiratory lung volume (EELV) in ventilated patients is assessed by analyzing the concentration changes of an inert gas during wash-in/wash-out maneuvers [1-4]. A recently developed alternative to EELV is the effective lung volume (ELV), which is based on a continuous breath-by-breath analysis of the carbon dioxide after alteration of the inspiratory pattern [5]. We showed that ELV detects lung derecruitment and recruitment [6] with the additional advantage of continuous monitoring of the ventilated patient.…”

Section: Introductionmentioning

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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Section: Introductionmentioning

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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“…As mentioned before CO 2 also enters the lung tissue where it dynamically equilibrates with the alveolar concentration so that its final elimination in exhaled air, the point of measurement, can be affected by several factors such as the ventilation-perfusion balance and the tissue-to-gas ratio in the lung. The foundations of the capnodynamic method to measure EELV were first proposed by Gedeon et al by introducing small short-lasting changes in the lung’s CO 2 balance by means of brief inspiratory holds added to the breathing pattern [ 20 ]. Later, Brewer et al, described a CO 2 rebreathing method obtaining good bias and limits of agreement in a first experimental evaluation with only a small overestimation compared to a nitrogen-based method despite applying a correction factor [ 21 ].…”

Section: Discussionmentioning

confidence: 99%

Clinical validation of a capnodynamic method for measuring end-expiratory lung volume in critically ill patients

Sanchez Giralt,

Tusman,

Wallin

et al. 2024

Crit Care

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Rationale End-expiratory lung volume (EELV) is reduced in mechanically ventilated patients, especially in pathologic conditions. The resulting heterogeneous distribution of ventilation increases the risk for ventilation induced lung injury. Clinical measurement of EELV however, remains difficult. Objective Validation of a novel continuous capnodynamic method based on expired carbon dioxide (CO2) kinetics for measuring EELV in mechanically ventilated critically-ill patients. Methods Prospective study of mechanically ventilated patients scheduled for a diagnostic computed tomography exploration. Comparisons were made between absolute and corrected EELVCO2 values, the latter accounting for the amount of CO2 dissolved in lung tissue, with the reference EELV measured by computed tomography (EELVCT). Uncorrected and corrected EELVCO2 was compared with total CT volume (density compartments between − 1000 and 0 Hounsfield units (HU) and functional CT volume, including density compartments of − 1000 to − 200HU eliminating regions of increased shunt. We used comparative statistics including correlations and measurement of accuracy and precision by the Bland Altman method. Measurements and main results Of the 46 patients included in the final analysis, 25 had a diagnosis of ARDS (24 of which COVID-19). Both EELVCT and EELVCO2 were significantly reduced (39 and 40% respectively) when compared with theoretical values of functional residual capacity (p < 0.0001). Uncorrected EELVCO2 tended to overestimate EELVCT with a correlation r2 0.58; Bias − 285 and limits of agreement (LoA) (+ 513 to − 1083; 95% CI) ml. Agreement improved for the corrected EELVCO2 to a Bias of − 23 and LoA of (+ 763 to − 716; 95% CI) ml. The best agreement of the method was obtained by comparison of corrected EELVCO2 with functional EELVCT with a r2 of 0.59; Bias − 2.75 (+ 755 to − 761; 95% CI) ml. We did not observe major differences in the performance of the method between ARDS (most of them COVID related) and non-ARDS patients. Conclusion In this first validation in critically ill patients, the capnodynamic method provided good estimates of both total and functional EELV. Bias improved after correcting EELVCO2 for extra-alveolar CO2 content when compared with CT estimated volume. If confirmed in further validations EELVCO2 may become an attractive monitoring option for continuously monitor EELV in critically ill mechanically ventilated patients. Trial registration: clinicaltrials.gov (NCT04045262).

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“…ELV, defined as the lung volume taking part into the gas exchange, was assessed as described earlier [ 39 , 40 ]. Briefly, periods of five consecutive alterations in inspiratory/expiratory ratio (1:2–1.5:1) were applied by the ventilator.…”

Section: Methodsmentioning

confidence: 99%

Cardiorespiratory effects of recruitment maneuvers and positive end expiratory pressure in an experimental context of acute lung injury and pulmonary hypertension

Doras

Guen²,

Peták

et al. 2015

BMC Pulm Med

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BackgroundRecruitment maneuvers (RM) and positive end expiratory pressure (PEEP) are the cornerstone of the open lung strategy during ventilation, particularly during acute lung injury (ALI). However, these interventions may impact the pulmonary circulation and induce hemodynamic and respiratory effects, which in turn may be critical in case of pulmonary hypertension (PHT). We aimed to establish how ALI and PHT influence the cardiorespiratory effects of RM and PEEP.MethodsRabbits control or with monocrotaline-induced PHT were used. Forced oscillatory airway and tissue mechanics, effective lung volume (ELV), systemic and right ventricular hemodynamics and blood gas were assessed before and after RM, during baseline and following surfactant depletion by whole lung lavage.ResultsRM was more efficient in improving respiratory elastance and ELV in the surfactant-depleted lungs when PHT was concomitantly present. Moreover, the adverse changes in respiratory mechanics and ELV following ALI were lessened in the animals suffering from PHT.ConclusionsDuring ventilation with open lung strategy, the role of PHT in conferring protection from the adverse respiratory consequences of ALI was evidenced. This finding advocates the safety of RM and PEEP in improving elastance and advancing lung reopening in the simultaneous presence of PHT and ALI.

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Cited by 25 publications

References 17 publications

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

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

Clinical validation of a capnodynamic method for measuring end-expiratory lung volume in critically ill patients

Cardiorespiratory effects of recruitment maneuvers and positive end expiratory pressure in an experimental context of acute lung injury and pulmonary hypertension

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