Assessment of cardiac output, intravascular volume status, and extravascular lung water by transpulmonary indicator dilution in critically III neonates and infants

Objective: To assess cardiac output, intrathoracic blood volume, global end-diastolic volume, and extravascular lung water in critically ill neonates and small infants using transpulmonary indicator dilution. Design: Prospective, observational, clinical study. Setting: Pediatric intensive care unit in a university hospital. Participants: Critically ill neonates and small infants suffering from severe heart failure, respiratory failure, or sepsis (n = 10). Interventions: A total of 194 transpulmonary indicator dilution measurements were done. Global end-diastolic volume, intrathoracic blood volume, and stroke volume were measured and compared with standard hemodynamic parameters during the clinical course and before and after volume loading (16 ± 3.7 mL/kg of 10% albumin solution) in 8 of 10 patients. Measurements and Main Results: A positive correlation was found for stroke volume index versus global end-diastolic volume (r = 0.76, p < 0.001) and intrathoracic blood volume (r = 0.56, p < 0.001). In contrast, no correlation was observed for stroke volume index versus central venous pressure. Volume loading resulted in significant increases in stroke volume index (p < 0.01), global end-diastolic volume (p < 0.01), and intrathoracic blood volume (p < 0.01); whereas central venous pressure, heart rate, mean arterial pressure, and extravascular lung water remained unchanged. Conclusion: Transpulmonary indicator dilution enables measurement of cardiac output and intravascular volume status in critically ill neonates and infants at the bedside. The effects of volume loading on cardiac preload and effective change in stroke volume can be monitored by this technique, whereas central venous pressure was not indicative of changes in intravascular volume status.