Question

Mechanical ventilation for adults and infants has similarities and differences.

1. Discuss what you have learned thus far when choosing ventilator settings for adults versus infants. For example, mode of ventilation in adults can be volume control whereas with infants the mode is pressure control. Choose another setting that you have observed and discuss.

Answer 1

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 delivery of high tidal volume), 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 (MOF)). 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 tidal volumes and mortality has not been demonstrated in the pediatric population. The relevance of VILI in the paediatric ICU population is thus unclear. Due to the physiological and biological differences in the respiratory system 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.

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.