Respiratory Mechanics in the Mechanically Ventilated Patient

Clement, Katherine; Courtney, Sherry E.; Dargaville, Peter A.; Heulitt, Mark J.; Khemani, Robinder G.; Newth, Christopher J. L.; Rimensberger, Peter C.; Tingay, David G.

doi:10.1007/978-3-642-01219-8_11

Cited by 4 publications

(4 citation statements)

References 137 publications

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“…However, our study did not prove this. On the contrary, the results suggest that the C w /C L ratio, especially before hernia repair, can be similar or lower than in neonates with healthy lungs (3-6) 7,[31][32][33][34] . It is an important issue that should be studied and explained in the future, especially in the context of the C decrease after operation.…”

Section: Discussionmentioning

confidence: 66%

“…From the point of view of a neonatal ventilation, the ratio between chest wall compliance and lung compliance (C w /C L ) is unfavourable, comparing to the older population. It amounts up to 3-6 in infants with healthy lungs [30][31][32] , whereas it www.nature.com/scientificreports/ is about 1 in healthy adults. As a result, an increase in tidal volume requires higher pressures in neonates than in adults.…”

Section: Discussionmentioning

confidence: 99%

“…Lungs of neonates with CDH are hypoplastic, smaller, with a reduced number of alveoli and compressed by herniated organs occupying the intrathoracic space 27 . These conditions influence respiratory system compliance (C) that can be several times lower compared to babies with healthy lungs [31][32][33][34] . Therefore, it might suggest that the C w /C L ratio should be higher than in healthy neonatal lungs.…”

Section: Discussionmentioning

confidence: 99%

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A new method of ventilation inhomogeneity assessment based on a simulation study using clinical data on congenital diaphragmatic hernia cases

Stankiewicz

Mierzewska-Schmidt

Pałko

et al. 2022

Sci Rep

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Congenital Diaphragmatic Hernia (CDH) is a diaphragm defect associated with lung hypoplasia and ventilation inhomogeneity (VI). The affected neonates are usually born with respiratory failure and require mechanical ventilation after birth. However, significant interindividual VI differences make ventilation difficult. So far, there are no clinical methods of VI assessment that could be applied to optimize ventilation at the bedside. A new VI index is a ratio of time constants T1/T2 of gas flows in both lungs. Pressure-controlled ventilation simulations were conducted using an infant hybrid (numerical-physical) respiratory simulator connected to a ventilator. The parameters of the respiratory system model and ventilator settings were based on retrospective clinical data taken from three neonates (2, 2.6, 3.6 kg) treated in the Paediatric Teaching Clinical Hospital of the Medical University of Warsaw. We searched for relationships between respiratory system impedance (Z) and ventilation parameters: work of breathing (WOB), peak inspiratory pressure (PIP), and mean airway pressure (MAP). The study showed the increased VI described by the T1/T2 index value highly correlated with elevated Z, WOB, PIP and MAP (0.8–0.9, the Spearman correlation coefficients were significant at P < 0.001). It indicates that the T1/T2 index may help to improve the ventilation therapy of CDH neonates.

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Section: Discussionmentioning

confidence: 66%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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A new method of ventilation inhomogeneity assessment based on a simulation study using clinical data on congenital diaphragmatic hernia cases

Stankiewicz

Mierzewska-Schmidt

Pałko

et al. 2022

Sci Rep

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“…Exogenous surfactant (200 mg/kg poractant alfa) was administered at 10 min. Total, tidal, elastic-dynamic (elas) and resistive (res) MP were calculated for tidal inflations minutely to 5 min and then at 10, 15, 30 and 90 min using the geometric method [ 7 ]. That is, MP total and MP tidal were calculated from the area of the airway pressure–volume loop multiplied with 0.098*respiratory rate, with positive end-expiratory pressure (PEEP) subtracted for MP tidal [ 8 ].…”

Section: Hypothesis-generating Data Setmentioning

confidence: 99%

Is mechanical power an under-recognised entity within the preterm lung?

Tingay

Naidu

Tingay

et al. 2023

ICMx

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Background Mechanical power is a major contributor to lung injury and mortality in adults receiving mechanical ventilation. Recent advances in our understanding of mechanical power have allowed the different mechanical components to be isolated. The preterm lung shares many of the same similarities that would indicate mechanical power may be relevant in this group. To date, the role of mechanical power in neonatal lung injury is unknown. We hypothesise that mechanical power maybe useful in expanding our understanding of preterm lung disease. Specifically, that mechanical power measures may account for gaps in knowledge in how lung injury is initiated. Hypothesis-generating data set To provide a justification for our hypothesis, data in a repository at the Murdoch Children’s Research Institute, Melbourne (Australia) were re-analysed. 16 preterm lambs 124–127d gestation (term 145d) who received 90 min of standardised positive pressure ventilation from birth via a cuffed endotracheal tube were chosen as each was exposed to three distinct and clinically relevant respiratory states with unique mechanics. These were (1) the respiratory transition to air-breathing from an entirely fluid-filled lung (rapid aeration and fall in resistance); (2) commencement of tidal ventilation in an acutely surfactant-deficient state (low compliance) and (3) exogenous surfactant therapy (improved aeration and compliance). Total, tidal, resistive and elastic-dynamic mechanical power were calculated from the flow, pressure and volume signals (200 Hz) for each inflation. Results All components of mechanical power behaved as expected for each state. Mechanical power increased during lung aeration from birth to 5 min, before again falling immediately after surfactant therapy. Before surfactant therapy tidal power contributed 70% of total mechanical power, and 53.7% after. The contribution of resistive power was greatest at birth, demonstrating the initial high respiratory system resistance at birth. Conclusions In our hypothesis-generating dataset, changes in mechanical power were evident during clinically important states for the preterm lung, specifically transition to air-breathing, changes in aeration and surfactant administration. Future preclinical studies using ventilation strategies designed to highlight different types of lung injury, including volu-, baro- and ergotrauma, are needed to test our hypothesis.

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A physiology-based mathematical model for the selection of appropriate ventilator controls for lung and diaphragm protection

Zhang

Ratano

Brochard

et al. 2020

J Clin Monit Comput

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Mechanical ventilation is used to sustain respiratory function in patients with acute respiratory failure. To aid clinicians in consistently selecting lung-and diaphragm-protective ventilation settings, a physiology-based decision support system is needed. To form the foundation of such a system, a comprehensive physiological model which captures the dynamics of ventilation has been developed. The Lung and Diaphragm Protective Ventilation (LDPV) model centers around respiratory drive and incorporates respiratory system mechanics, ventilator mechanics, and blood acid-base balance. The model uses patient-specific parameters as inputs and outputs predictions of a patient's transpulmonary and esophageal driving pressures (outputs most clinically relevant to lung and diaphragm safety), as well as their blood pH, under various ventilator and sedation conditions. Model simulations and global optimization techniques were used to evaluate and characterize the model. The LDPV model is demonstrated to describe a CO 2 respiratory response that is comparable to what is found in literature. Sensitivity analysis of the model indicate that the ventilator and sedation settings incorporated in the model have a significant impact on the target output parameters. Finally, the model is seen to be able to provide robust predictions of esophageal pressure, transpulmonary pressure and blood pH for patient parameters with realistic variability. The LDPV model is a robust physiological model which produces outputs which directly target and reflect the risk of ventilator-induced lung and diaphragm injury. Ventilation and sedation parameters are seen to modulate the model outputs in accordance with what is currently known in literature.

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Respiratory Mechanics in the Mechanically Ventilated Patient

Cited by 4 publications

References 137 publications

A new method of ventilation inhomogeneity assessment based on a simulation study using clinical data on congenital diaphragmatic hernia cases

A new method of ventilation inhomogeneity assessment based on a simulation study using clinical data on congenital diaphragmatic hernia cases

Is mechanical power an under-recognised entity within the preterm lung?

A physiology-based mathematical model for the selection of appropriate ventilator controls for lung and diaphragm protection

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