Effect of intraventricular hemorrhage on pulmonary function in newborn piglets

Intracranial hemorrhage in the premature infant is often associated with respiratory failure and need for mechanical ventilation. We therefore addressed the question of possible interactions with and pulmonary consequences of intraventricular hemorrhage. Newborn piglets were studied during intraventricular hemorrhage simulated by intraventricular blood infusion. Infusion volume amounted to 8% of estimated brain weight. Respiratory rate, minute ventilation, lung resistance and dynamic lung compliance, as well as arterial blood gases, arterial and intraventricular pressures were measured. The piglets were mechanically ventilated with a low basal rate of 20 breaths per minute throughout the study. All piglets experienced significant rise in intraventricular pressure and respiratory failure during the study. Respiratory failure was mainly a result of a reduction in respiratory frequency and minute ventilation until apnea. However, a rise in lung resistance was also noted while lung compliance did not change. We conclude that increased need for mechanical ventilation during intracranial hemorrhage is primarilty a consequence of hypoventilation. The increase seen in lung resistance could also suggest that intraventricular hemorrhage causes an element of bronchiolar constriction. Furthermore, these effects are not only a result of the increase in intraventricular pressure, but specific effects of blood components within the central nervous system must be considered.