Prone position delays the progression of ventilator-induced lung injury in rats: Does lung strain distribution play a role?*

Abstract

Prone position delays the progression of ventilator-induced lung injury. Computed tomography scan analysis suggests that a more homogeneous distribution of strain may be implicated in the protective role of prone position against ventilator-induced lung injury.

Should Early Prone Positioning Be a Standard of Care in ARDS With Refractory Hypoxemia?

“…12,29 For the same tidal volume and PEEP combination, ventilating large animals in the prone position reduces the severity of ventilator-inflicted lung damage. 24,30,31 Using the very high but irrefutable outcome threshold of improved overall mortality, most large clinical trials conducted over the last 20 y were unable to confirm a survival benefit in diverse populations of subjects labeled as having acute lung injury/ARDS. [14][15][16][17] Clearly, not everyone benefits from face-down positioning, yet post-trial subgroup analyses have hinted that certain patient subgroups might indeed benefit from the prone orientation.…”

Ajustes da pressão positiva expiratória final ideal na síndrome do desconforto respiratório agudo na posição prona

“…. Até hoje, essa síndrome vem sendo estudada em seus mais diversos aspectos, Na procura de oferecer estratégias de ventilação mecânica que buscam manter a ventilação e a oxigenação necessárias para a sobrevivência destes pacientes, além de diminuir a lesão pulmonar ocasionada pela pressão positiva [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20] . A posição em decúbito ventral (posição prona) aplicada em pacientes com SDRA tem demonstrado melhora da oxigenação em mais de 70% dos casos, além da melhora da heterogeneidade parenquimatosa, da complacência pulmonar, da relação ventilação-perfusão V/Q, diminuição do shunt intrapulmonar, melhora da vasoconstrição pulmonar, do recrutamento alveolar de áreas anteriormente dependentes da gravidade e redução da lesão pulmonar induzida pela ventilação mecânica.…”

New and Conventional Strategies for Lung Recruitment in Acute Respiratory Distress Syndrome

“…Some authors have reported that in healthy [23], as well as in lung-injured animals [24], mechanical ventilation leading to lung overdistension and cyclic collapse/reopening was associated with less extensive histological change in dorsal regions in the prone, as compared to the supine position. Although the claim that body position aff ects the distribution of lung injury has been challenged, the development of VILI due to excessively high V T seems to be delayed during prone compared to supine positioning [25].…”

“…Th e reduction or delay in the development of VILI in the prone position can be explained by diff erent mechanisms: (a) A more homogeneous distribution of transpulmonary pressure gradient due to changes in the lung-thorax interactions and direct transmission of the weight of the abdominal contents and heart [22], yielding a redistribution of ventilation; (b) increased endexpiratory lung volume resulting in a reduction in stress and strain [25]; and (c) changes in regional perfusion and/or blood volume [26]. In a paraquat model of ALI, the prone position was associated with a better perfusion in ventral and dorsal regions, a more homogeneous distribution of alveolar aeration which reduced lung mechanical changes and increased end expiratory lung volume and oxygenation [27].…”

“…Some authors have reported that in healthy [23], as well as in lung-injured animals [24], mechanical ventilation leading to lung overdistension and cyclic collapse/reopening was associated with less extensive histological change in dorsal regions in the prone, as compared to the supine position. Although the claim that body position aff ects the distribution of lung injury has been challenged, the development of VILI due to excessively high V T seems to be delayed during prone compared to supine positioning [25].Th e reduction or delay in the development of VILI in the prone position can be explained by diff erent mechanisms: (a) A more homogeneous distribution of transpulmonary pressure gradient due to changes in the lung-thorax interactions and direct transmission of the weight of the abdominal contents and heart [22], yielding a redistribution of ventilation; (b) increased endexpiratory lung volume resulting in a reduction in stress and strain [25]; and (c) changes in regional perfusion and/or blood volume [26]. In a paraquat model of ALI, the prone position was associated with a better perfusion in ventral and dorsal regions, a more homogeneous distribution of alveolar aeration which reduced lung mechanical changes and increased end expiratory lung volume and oxygenation [27].…”