RESUMEN
OBJECTIVE: To determine in peripheral blood samples of newborns (NB) cardiac output (Q), cardiac index (CI), systemic vascular resistance index (SVRI), and effective oxygen transport (EO2T), through arteriovenous oxygen content difference ([C(a-v) O2]). DESIGN: Comparative survey. SETTING: Healthy NBs and NBs in intermediate care in third level medical attention units. MATERIAL AND METHODS: Forty-seven NB (17 pre-term) were prospectively studied in August and September/1995. A blood sample of 0.4 mL was taken from the umbilical or femoral vein and from the umbilical, radial or femoral artery. The inferencial statistics were done with a t test and Pearson's correlation coefficient. Significance was considered if p < 0.05. RESULTS: Cardiac output ranged from 0.3 to 1.4, mean = 0.6 L/min +/- 0.24 (+/- SD); CI ranged from 1.8 to 6.4 L/min/m2 body surface area (mean = 3.3 +/- 1.2); SVRI ranged from 533 to 2,391 dyne/sec/cm-5/m2 BSA (mean = 1,317 +/- 494); EO2T ranged from 307 to 1,017 mL/min/m2 BSA (mean = 549 +/- 186); the [C(a-v) O2] ranged from 3.1 to 10.7% in volume (mean = 6.8 +/- 2.1). No significant differences were found in Q between pre-term and full-term NB nor was there any correlation between Q and gestational age. CONCLUSIONS: The [C (a-v)O2] is a good alternative to obtain indexes in peripheral blood of NB without cardiopathy, whenever other less invasive and more sophisticated methods are unavailable. In order to calculate the indexes in critically-ill patients, it is necessary to measure O2 consumption prior to applying this method.