High renal regional oxygen saturation in femoral arteriovenous fistula after neonatal cardiac surgery

The use of an indwelling arterial catheter is standard practice in the postoperative monitoring of paediatric cardiac surgery patients. Arteriovenous fistula related to this procedure can be difficult to diagnose. Regional haemoglobin oxygen saturation (rSO 2 ) using near-infrared spectroscopy and central venous oxygen saturation (ScvO 2 ) are monitored to follow the balance between oxygen consumption and delivery. Low values of these parameters are a sign of low cardiac output. High rSO 2 and high ScvO 2 are less frequently described. We report the discovery of an iatrogenic arteriovenous fistula in a neonate after cardiac surgery who had unexpectedly high values of renal rSO 2 and femoral ScvO 2 . High renal rSO 2 after femoral instrumentation should alert the physician to the possibility of arteriovenous fistula.