Evaluation of the right atrial venous oxygen saturation as a physiologic monitor in a neonatal model

Abstract

Pulmonary artery (PA) mixed venous saturation (SvO2) has become a crucial monitor in the adult intensive care unit, but is not used in neonates because of the difficulty in PA catheterization. We evaluated the possibility of utilizing the right atrial venous oxygen saturation (RAvO2), which is easily accessed in the neonate, as a monitor of the effects of mechanical ventilation and intravascular volume in an animal model selected to be the size of the human neonate. A continuous RAvO2 monitoring catheter was placed into the right atrium of 16 normal rabbits (2.2 to 4.1 kg). Oxygen delivery was manipulated by alterations in peak inspiratory pressure (PIP) (n = 6), positive end-expiratory pressure (PEEP) (n = 6), or by progressive hypovolemia (n = 4). RAvO2 decreased with onset of mechanical ventilation alone from 69% +/- 6% to 61% +/- 5% (P < .01). As the PIP was increased from 12 to 21 cm H2O, the RAvO2 progressively decreased from 59% +/- 4% to 49% +/- 6% (P < .05). As the PEEP was increased from 3 to 9 cm H2O, the RAvO2 progressively decreased from 64% +/- 5% to 33% +/- 16% (P < .01). RAvO2 approached baseline after return to continuous positive airway pressure (CPAP) of 3 cm H2O. Progressive phlebotomy to a total of 10 mL/kg resulted in a decrease in RAvO2 from 70% +/- 6% to 27% +/- 5% (P < .001). Volume resuscitation resulted in an increase in RAvO2 to near baseline. Peripheral arterial oxygen saturation remained at a constant 100% throughout each protocol.(ABSTRACT TRUNCATED AT 250 WORDS)

Central venous oxygen saturation monitoring in the critically ill patient

“…Despite studies questioning the value of SvO 2 in treating ICU patients [45, [53][54][55], considerable evidence suggests that ScvO 2 has a beneficial role in the early management of critically ill patients and even neonates [25,56]. The ability to access this information earlier in the phases of critical illness is now a reality and further studies are now in progress to confirm that early recognition and treatment of deranged ScvO 2 values have significant outcome benefit.…”

Correlation between central venous oxygen saturation and oxygen delivery changes following fluid therapy

“…Several studies report a significant increase in ScvO 2 following volume loading both in animals 11–14 and in humans 1,2 . The increase in ScvO 2 was associated with an increase in cardiac output and in oxygen delivery to tissues 14,15 .…”

“…Moreover, Pearse et al 6 evaluated changes in ScvO 2 following major surgery and found that tissues' oxygen consumption is an important determinant of ScvO 2 Second, this study was based on spot in vitro measurements of ScvO 2 . Several authors have used central venous fiberoptic oxygen saturation catheters to assess the clinical usefulness of ScvO 2 4,7,10,13 . These catheters provided an accurate continuous monitoring of central venous oxygen saturation, a large number of measurements and a close tracking of ScvO 2 changes across a wide range of hemodynamic conditions.…”

“Shunt index” can be used to predict clinically significant patent ductus arteriosus in premature neonates in early post-natal life

“…[1][2][3][4][5][6][7] It is also used for monitoring the response to therapy and for follow-up of infants with patent ductus arteriosus. In neonatal intensive care units, umbilical arterial and venous catheters are used frequently either to monitor blood pressure or to administer medication and parenteral nutrition.…”