Outline the potential mechanisms of ventilator associated lung injury in patients with Acute Respiratory Distress Syndrome and the steps that can be taken to minimise them.
Injury |
Mechanism |
Minimisation Strategy |
Volutrauma |
Non-homogenous lung injury |
Avoid over-distending the “baby lung” of ARDS:
|
Barotrauma |
Increasing the trans-pulmonary pressures above |
|
Biotrauma |
Mechanotransduction and tissue disruption leads to upregulation and release of chemokines and |
Protective lung ventilation
|
Recruitment / |
The weight of the oedematous lung in ARDS contributes to collapse of the dependant portions of the lung |
Consider recruiting collapsed lung +/- employing an open lung ventilation strategy. |
Shearing |
This occurs at junction of the collapsed lung and ventilated lung. The ventilated alveoli move against the relatively fixed collapsed lung with high shearing force and subsequent injury. |
|
Oxygen |
Higher than necessary FiO2 overcomes the ability of the cells to deal with free oxygen free radicals and leads to oxygen related free radical related |
Limit FiO2 through the use of |
This question interrogates one's understanding of ARDS ventilation strategies.
Its difficult to add to the already comprehensive list of answers provided by the college.
Here is a good review article on ventilator-associated lung injury in general.
A more recent discussion is also available.
The combination of these two articles was the source of my own summary, which was supposed to trim the theoretical fat away, and leave behind dry factual bones... Pity it never turns out like that. I think the word count of this "summary" far exceeds the combined word count of both the publications.
Rocco PR, Dos Santos C, Pelosi P. Pathophysiology of ventilator-associated lung injury. Curr Opin Anaesthesiol. 2012 Apr;25(2):123-30
Caironi P et al, Lung opening and closing during ventilation of acute respiratory distress syndrome. Am J Respir Crit Care Med. 2010;181(6):578.
The Acute Respiratory Distress Syndrome Network.Ventilation with lower tidal volumes as compared with traditional tidal volumes for acute lung injury and the acute respiratory distress syndrome. N Engl J Med. 2000;342(18):1301.
Brower RG, Lanken PN, MacIntyre N, et al: Higher versus lower positive end-expiratory pressures in patients with the acute respiratory distress syndrome. N Engl J Med 351:327–336, 2004.
Pinhu, Liao, et al. "Ventilator-associated lung injury." The Lancet 361.9354 (2003): 332-340.
Tremblay, Lorraine N., and Arthur S. Slutsky. "Ventilator-induced lung injury: from the bench to the bedside." Applied Physiology in Intensive Care Medicine 1. Springer Berlin Heidelberg, 2012. 343-352.