Author:

Keywords:

1114 Paediatrics and Reproductive Medicine, Pediatrics

Abstract:

Background and aims: Superior vena cava(SVC)-flow measurement is used as a surrogate marker for cardiac output in premature neonates. Low SVC-flow is associated with poor neurodevelopmental outcome. Our aim was to assess the contribution of cerebral perfusion on SVC-flow in an experimental model at two different levels of pCO2. Materials and methods: 13 newborn piglets were studied and hemodynamically monitored. Cerebral perfusion was measured with near infrared spectroscopy(rSO2)and colored microsphere perfusion technique. Ultrasound was used to assess SVC-flow. All measurements were performed at normoventilation, both during normal CO2 levels and at hypercapnia where extra CO2 was added. Paired t-test was used where appropriate, and linear mixed model were used to assess the effect of change in pCO2 on SVC-flow and cerebral perfusion. Results: We observed an increase in rSO2 (39±2 to 52±2, p< 0.01) and cerebral blood flow in the left(60±8 to 153±22ml/min/100g, p< 0.01) and right(67±11 to 162±33ml/min/100g, p=0.01) cortex in piglets exposed to high(9.2±0.2 kPa) vs. low (4.2±0.1 kPa, p< 0.01) pCO2. Systemic mean blood pressure decreased (89±5mmHg to 72±4mmHg), while heart rate did not change(226±15 vs. 242±16 BPM, p=0.46). Ultrasonographic measured SVC-flow changed from 51±7 to 72±10 ml/kg/min(p< 0.01. Both rSO2 (p< 0.01) and pCO2 (p< 0.01) was found to determine both SVC- flow as well as cerebral perfusion. Conclusions: Our study demonstrates a significant impact of pCO2 and cerebral perfusion on SVC- flow. This supports the hypothesis that cerebral perfusion is a determinant factor for SVC-flow.