Ventilator-induced lung injury. Similarity and differences between children and adults

Abstract

It is well established that mechanical ventilation can injure the lung, producing an entity known as ventilator-induced lung injury (VILI). There are various forms of VILI, including volutrauma (i.e., injury caused by overdistending the lung), atelectrauma (injury due to repeated opening/closing of lung units), and biotrauma (release of mediators that can induce lung injury or aggravate pre-existing injury, potentially leading to multiple organ failure). Experimental data in the pediatric context are in accord with the importance of VILI, and appear to show age-related susceptibility to VILI, although a conclusive link between use of large Vts and mortality has not been demonstrated in this population. The relevance of VILI in the pediatric intensive care unit population is thus unclear. Given the physiological and biological differences in the respiratory systems of infants, children, and adults, it is difficult to directly extrapolate clinical practice from adults to children. This Critical Care Perspective analyzes the relevance of VILI to the pediatric population, and addresses why pediatric patients might be less susceptible than adults to VILI.

Keywords: animal studies; human studies; mechanical ventilation; pediatrics; ventilator-induced lung injury.

Figure 1

This simplified illustration of an alveolus summarizes the differences in ventilator-induced lung injury (VILI) between the pediatric (left) and the adult lung (right). Injurious, high Vt ventilation may lead to an increased surfactant production in the pediatric compared with the adult lung, with higher levels of large aggregates. Next, there may be a greater degree of alveolar and interstitial infiltration by polymorphonuclear leukocytes, production of proinflammatory mediators, such as IL-6 and TNF-α, a decreased production of anti-inflammatory mediators, including IL-10, protein leakage, and more hyaline membrane formation in the adult lung. It may also be surmised that a fixed Vt causes different lung strain between the pediatric and the adult lung. Elastin and collagen levels differ significantly between the pediatric and the adult lung.