Hemodynamic and manometric observations in experimental air-block syndrome

In experimental air block, interstitial emphysema is characterized by early tachypnea, arterial hypertension, and hypoxemia. Pneumomediastinum causes a significant rise in central venous pressure and an initial respiratory and subsequent metabolic acidosis. This is a result of a reduction in venous return, cardiac output, and tissue perfusion. Pneumopericardium and coronary and systemic arterial air emboli were observed when vigorous insufflation pressures were used. Animal deterioration was characterized by severe hypoxia, metabolic and respiratory acidosis, arterial hypotension, and cardiac arrhythmias leading to cardiac arrest. These observations point out the potential dangers of vigorous resuscitation in small infants and suggest that vena caval and esophageal manometrics, arterial blood pressure, pH, and blood gas tension determinations indicate significant changes in pulmonary and mediastinal hemodynamics. Monitoring these factors in addition to pulse, respiration, and the EKG would permit early detection of critical changes and allow for prompt respiratory support and, hopefully, improved survival rates in infants with air-block syndrome.