Background Septic shock in neonates remains a significant cause of neonatal mortality and morbidity. Decreased peripheral vascular resistance and relative or absolute hypovolemia are the major pathogenic factors of septic shock in adults. The haemodynamic presentation and course of septic shock in neonates is not known.

Methods Blood pressure, right and left ventricular output (RVO, LVO) and superior vena cava flow (SVC flow) of infants who had a suspected infection and showed signs of cardiovascular compromise were collected every 12 hours until clinical recovery. The treatment protocol for hypotension in sepsis was a pressure based approach.

Results Twelve infants with a median (IQR) gestational age of 28 (25–30) weeks were measured. Two patients died. Mean (SD) RVO, LVO and SVC flow at first measurement was 560 (168), 482 (193) and 101 (43) ml/kg/min respectively. The mean calculated SVR was 0.09 (0.04) mmHg/ml/kg/min. There was no significant change of RVO and LVO and a significant increase in SVC flow over the study period in the 10 survivors (mean difference RVO 1%; 95%CI −12,14%, SVC flow 37%; 95%CI 7,68%, LVO 5%; 95%CI −4,13%). Blood flow was significantly decreased in the 2 non-survivors in the first 12 hours (mean difference RVO −54%; 95%CI −59, −50%, LVO −53%; 95%CI −90, −17%, SVC flow −43%; 95%CI −51, −35%).

Conclusion Neonates who develop sepsis present with relative high left and right cardiac outputs. This implies that a reduction in SVR is the dominant haemodynamic feature. A decrease in RVO or LVO of more then 50% compared to the initial measurement is associated with mortality.