Correlation of abdominal site near-infrared spectroscopy with gastric tonometry in infants following surgery for congenital heart disease

Objective: Splanchnic oximetry, as measured by near-infrared spectroscopy (NIRS), correlates with gastric tonometry as a means of assessing regional (splanchnic) oxygenation and perfusion. Design: Prospective, data-gathering study. Setting: Pediatric cardiac intensive care unit in a tertiary care children's hospital. Subjects: Neonates and infants with congenital heart disease who underwent catheter intervention or surgical repair requiring cardiopulmonary bypass. Interventions: None. Measurements and Main Results: Twenty neonates and infants were studied within 48 hrs of surgery. We measured somatic saturation (602) via NIRS sensors placed over the anterior abdomen (splanchnic bed) and dorsal lateral flank (renal bed). Somatic rSO(2) readings were paired with simultaneous points of intramucosal gastric pH (pH(i)), measured by tonometry. The rSO(2) readings were paired with serum lactate and measurements of systemic mixed venous saturation (S (v) over baro(2)). There was strong correlation between the abdominal rSo(2) and pH, (r = .79; p < .0001) as well as between abdominal rSO(2) and S<(v)over bar>o(2) (r.89; p <.0001). There was also significant negative correlation between the abdominal rSO(2) and serum lactate (r = .77; p < .0001). Correlations between the dorsal lateral (renal) rSO(2) measurements and serum lactate and S (v) over baro(2) were also significant but not as strong. Conclusions., Abdominal site rSO(2) measured in infants with either single or biventricular physiology, exhibits a strong correlation with gastric pH(i) as well as with serum lactate and S (v) over baro(2). The results indicate that rSO(2) measurements over the anterior abdominal wall correlate more strongly than flank rSO(2) with regard to systemic indices of oxygenation and perfusion. This study suggests that the NIRS monitor is a valid modality to obtain an easy, immediate, and noninvasive measurement of splanchnic rSO(2) in infants following cardiac surgery for congenital heart disease.