Lung Stress and Strain during Mechanical Ventilation

Protti, Alessandro; Cressoni, Massimo; Santini, Alessandro; Länger, Thomas; Mietto, Cristina; Febres, Daniela; Chierichetti, Monica; Coppola, Silvia; Conte, G.; Gatti, Stefano; Leopardi, O; Masson, Serge; Lombardi, Luciano; Lazzerini, M.; Rampoldi, Erica; Cadringher, Paolo; Gattinoni, Luciano

doi:10.1164/rccm.201010-1757oc

Cited by 290 publications

(262 citation statements)

References 23 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: 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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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: 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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“…The study was approved by the Institutional Review Board and conducted in accordance with international recommendations [10]. Twelve healthy female pigs weighing 22 ± 3 kg were anesthetized and mechanically ventilated (Engstrom Carestation, GE Healthcare) with PEEP 5 cm H 2 O, tidal volume 10 ml/kg and respiratory rate adjusted to maintain PCO 2 constant throughout the experiment by capnography.…”

Section: Methodsmentioning

confidence: 99%

In vivo conditioning of acid–base equilibrium by crystalloid solutions: an experimental study on pigs

et al. 2012

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Purpose: Large infusion of crystalloids may induce acid-base alterations according to their strong ion difference ([SID]). We wanted to prove in vivo, at constant PCO 2 , that if the [SID] of the infused crystalloid is equal to baseline plasma bicarbonate, the arterial pH remains unchanged, if lower it decreases, and if higher it increases. Methods: In 12 pigs, anesthetized and mechanically ventilated at PCO 2 &40 mmHg, 2.2 l of crystalloids with a [SID] similar to (lactated Ringer's 28.3 mEq/l), lower than (normal saline 0 mEq/l), and greater than (rehydrating III 55 mEq/l) baseline bicarbonate (29.22 ± 2.72 mEq/l) were infused for 120 min in randomized sequence. Four hours of wash-out were allowed between the infusions. Every 30 min up to minute 120 we measured blood gases, plasma electrolytes, urinary volume, pH, and electrolytes. Albumin, hemoglobin, and phosphates were measured at time 0 and 120 min. Results: Lactated Ringer's maintained arterial pH unchanged (from 7.47 ± 0.06 to 7.47 ± 0.03) despite a plasma dilution around 12%. Normal saline caused a reduction in pH (from 7.49 ± 0.03 to 7.42 ± 0.04) and rehydrating III induced an increase in pH (from 7.46 ± 0.05 to 7.49 ± 0.04). The kidney reacted to the infusion, minimizing the acidbase alterations, by increasing/ decreasing the urinary anion gap, primarily by changing sodium and chloride concentrations. Lower urine volume after normal saline infusion was possibly due to its greater osmolarity and chloride concentration as compared to the other solutions. Conclusions: Results support the hypothesis that at constant PCO 2 , pH changes are predictable from the difference between the [SID] of the infused solution and baseline plasma bicarbonate concentration.

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“…Newer data generated by quantitative computed tomography suggest that alveolar overstretching tends to manifest when the V T and PEEP more than double the aerated functional residual capacity. 18,19 The resulting overstretch ruptures the matrix and may threaten to disrupt the fibrous skeleton of the lung. Rupture is especially likely when there is force amplification (stress focusing) within a heterogeneous lung 20,21 or weakened integrity of the interconnecting tissues.…”

Section: Airway Injurymentioning

confidence: 99%

Ventilator-Associated Problems Related to Obstructive Lung DiseaseDiscussion

Marini

2013

Respir Care

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SummaryRelatively little attention has been directed toward damage inflicted upon the airway network that connects the alveoli, or toward the problems caused by invasive ventilation for patients with severe airflow obstruction. Mechanical ventilation with positive pressure can cause non-edematous barotrauma, inflict airway injury, and promote lung remodeling. Interactions between patient and ventilator, largely mediated through dynamic hyperinflation, include functional consequences for hemodynamics, respiratory muscle function, breathing work load, and patient-ventilator synchrony. Awareness of such associations not only helps to avoid complications during and after the critical phase of obstructive illness, but also opens a window to improved patient comfort and safety. The purpose of this review is to survey the range of structural damages and functional impairments that occur in an "obstructive" context.

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Lung Stress and Strain during Mechanical Ventilation

Abstract: In healthy pigs, ventilator-induced lung damage develops only when a strain greater than 1.5-2 is reached or overcome. Because of differences in intrinsic lung properties, caution is warranted in translating these findings to humans.

Cited by 290 publications

References 23 publications

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

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

In vivo conditioning of acid–base equilibrium by crystalloid solutions: an experimental study on pigs

Ventilator-Associated Problems Related to Obstructive Lung DiseaseDiscussion

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