Lung Stress and Strain During Mechanical Ventilation

Protti, Alessandro; Andreis, Davide T.; Monti, Massimo; Santini, Alessandro; Sparacino, Cristina Carin; Länger, Thomas; Votta, Emiliano; Gatti, Stefano; Lombardi, Luciano; Leopardi, O; Masson, Serge; Cressoni, Massimo; Gattinoni, Luciano

doi:10.1097/ccm.0b013e31827417a6

Cited by 237 publications

(119 citation statements)

References 30 publications

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“…However, the strain calculations based on EELV might be a useful parameter at the bedside to assess ventilator settings. The studies of Protti et al 9, 19. clearly demonstrated that tidal volume is harmful to the lungs, whereas PEEP worked protective.…”

Section: Discussionmentioning

confidence: 98%

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Lung stress and strain calculations in mechanically ventilated patients in the intensive care unit

Blankman

Hasan

Bikker

et al. 2015

Acta Anaesthesiol Scand

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BackgroundStress and strain are parameters to describe respiratory mechanics during mechanical ventilation. Calculations of stress require invasive and difficult to perform esophageal pressure measurements. The hypothesis of the present study was: Can lung stress be reliably calculated based on non‐invasive lung volume measurements, during a decremental Positive end‐expiratory pressure (PEEP) trial in mechanically ventilated patients with different diseases?MethodsData of 26 pressure‐controlled ventilated patients admitted to the ICU with different lung conditions were retrospectively analyzed: 11 coronary artery bypass graft (CABG), 9 neurology, and 6 lung disorders. During a decremental PEEP trial (from 15 to 0 cmH2O in three steps) end‐expiratory lung volume (EELV) measurements were performed at each PEEP step, without interruption of mechanical ventilation. Strain, specific elastance, and stress were calculated for each PEEP level. Elastance was calculated as delta PEEP divided by delta PEEP volume, whereas specific elastance is elastance times the FRC. Stress was calculated as specific elastance times the strain. Global strain was divided into dynamic (tidal volume) and static (PEEP) strain.ResultsStrain calculations based on FRC showed mainly changes in static component, whereas calculations based on EELV showed changes in both the static and dynamic component of strain. Stress calculated from EELV measurements was 24.0 ± 2.7 and 13.1 ± 3.8 cmH2O in the lung disorder group at 15 and 5 cmH2O PEEP. For the normal lungs, the stress values were 19.2 ± 3.2 and 10.9 ± 3.3 cmH2O, respectively. These values are comparable to earlier publications. Specific elastance calculations were comparable in patients with neurologic and lung disorders, and lower in the CABG group due to recruitment in this latter group.ConclusionStress and strain can reliably be calculated at the bedside based on non‐invasive EELV measurements during a decremental PEEP trial in patients with different diseases.

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Section: Discussionmentioning

confidence: 98%

“…Tidal ventilation is a dynamic process, as the energy is cyclically applied to the lungs. Therefore, lung deformation due to tidal volume is called dynamic strain 9. Static strain and dynamic strain are calculated according to the following formulas (2 and 3)9:

{Strain}_{normalstatic} = \frac{V_{PEEP}}{FRC}

{Strain}_{normaldynamic} = \frac{V_{T}}{FRC}

…”

Section: Methodsmentioning

confidence: 99%

Lung stress and strain calculations in mechanically ventilated patients in the intensive care unit

Blankman

Hasan

Bikker

et al. 2015

Acta Anaesthesiol Scand

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“…We have previously shown that healthy piglets ventilated for 54 h with high PEEP (never removed) and low V T survive with normal lungs [4]. There, lack of pulmonary oedema could have been attributed to diminished transmural pulmonary capillary pressure (that drives fluid extravasation) across an abnormally highly permeable (overstretched) blood-gas barrier.…”

Section: Discussionmentioning

confidence: 99%

“…Based on a previous study [4], we expected that the volume of gas so inflated in the form of PEEP would have been around 75% and V T around 25% of IC (TLC minus FRC). Therefore, the volume of gas inflated by end of inspiration (volume of gas due to PEEP plus V T ) was predicted to be equal to IC and end-inspiratory lung volume, including FRC, to approach TLC.…”

Section: Methodsmentioning

confidence: 99%

“…We have recently shown that healthy piglets ventilated with no positive end-expiratory pressure (PEEP) and with tidal volume (V T ) close to inspiratory capacity (IC) die with inflammatory pulmonary oedema within 36 h. In contrast, those ventilated with high PEEP (≥18 cmH 2 O; volume of gas around 75% of IC) and low V T (25% of IC) survive with normal lungs for 54 h [4]. …”

Section: Introductionmentioning

confidence: 99%

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High positive end-expiratory pressure: only a dam against oedema formation?

et al. 2013

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IntroductionHealthy piglets ventilated with no positive end-expiratory pressure (PEEP) and with tidal volume (VT) close to inspiratory capacity (IC) develop fatal pulmonary oedema within 36 h. In contrast, those ventilated with high PEEP and low VT, resulting in the same volume of gas inflated (close to IC), do not. If the real threat to the blood-gas barrier is lung overinflation, then a similar damage will occur with the two settings. If PEEP only hydrostatically counteracts fluid filtration, then its removal will lead to oedema formation, thus revealing the deleterious effects of overinflation.MethodsFollowing baseline lung computed tomography (CT), five healthy piglets were ventilated with high PEEP (volume of gas around 75% of IC) and low VT (25% of IC) for 36 h. PEEP was then suddenly zeroed and low VT was maintained for 18 h. Oedema was diagnosed if final lung weight (measured on a balance following autopsy) exceeded the initial one (CT).ResultsAnimals were ventilated with PEEP 18 ± 1 cmH2O (volume of gas 875 ± 178 ml, 89 ± 7% of IC) and VT 213 ± 10 ml (22 ± 5% of IC) for the first 36 h, and with no PEEP and VT 213 ± 10 ml for the last 18 h. On average, final lung weight was not higher, and actually it was even lower, than the initial one (284 ± 62 vs. 347 ± 36 g; P = 0.01).ConclusionsHigh PEEP (and low VT) do not merely impede fluid extravasation but rather preserve the integrity of the blood-gas barrier in healthy lungs.

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