Severe pneumonia with pneumatoceles and patent foramen ovale in an infant: optimal ventilation strategy?
We discuss a case of severe pneumonia with pneumatoceles in a 2-month old infant. Despite peak and plateau airway pressures kept below 30 and 25cmH2O, respectively, the infant developed bilateral pneumothorax and pneumomediastinum caused by pneumatocele rupture, necessitating bilateral intercostal drainage. Application of positive end-expiratory pressure (PEEP) of 10cmH2O at FiO2 of 0.7 worsened oxygenation, and transthoracic echocardiography showed right-to-left shunting of blood through the patent foramen ovale. Therefore, PEEP had to be tapered to 6cmH2O, and ventilation carried out at FiO2 of 1 until the lung condition improved. The open lung strategy of higher increments of PEEP and lower FiO2 for lung protective ventilation actually proved deleterious to our patient. We conclude that a subset of patients with acute respiratory distress syndrome with refractory hypoxaemia may have right-to-left shunting of blood through a patent foramen ovale. This can be detected by echocardiography, and these patients may benefit from a ventilation strategy aimed at lowering pulmonary vascular resistance.
Crit Care Resusc 2006; 8: 209–212
