Does metabolic alkalosis influence cerebral oxygenation in infantile hypertrophic pyloric stenosis?

BACKGROUND: This pilot study focuses on regional tissue oxygenation (rSO2 ) in patients with infantile hypertrophic pyloric stenosis in a perioperative setting. To investigate the influence of enhanced metabolic alkalosis (MA) on cerebral (c-rSO2 ) and renal (r-rSO2 ) tissue oxygenation, two-site near-infrared spectroscopy (NIRS) technology was applied.

MATERIALS AND METHODS: Perioperative c-rSO2 , r-rSO2 , capillary blood gases, and electrolytes from 12 infants were retrospectively compared before and after correction of MA at admission (T1), before surgery (T2), and after surgery (T3).

RESULTS: Correction of MA was associated with an alteration of cerebral oxygenation without affecting renal oxygenation. When compared to T1, 5-min mean (± standard deviation) c-rSO2 increased after correction of MA at T2 (72.74 ± 4.60% versus 77.89 ± 5.84%; P = 0.058), reaching significance at T3 (80.79 ± 5.29%; P = 0.003). Furthermore, relative 30-min c-rSO2 values at first 3 h of metabolic compensation were significantly lowered compared with postsurgical states at 16 and 24 h. Cerebral oxygenation was positively correlated with levels of sodium (r = 0.37; P = 0.03) and inversely correlated with levels of bicarbonate (r = -0.34; P = 0.05) and base excess (r = -0.36; P = 0.04). Analysis of preoperative and postoperative cerebral and renal hypoxic burden yielded no differences. However, a negative correlation (r = -0.40; P = 0.03) regarding hematocrite and mean r-rSO2 , indirectly indicative of an increased renal blood flow under hemodilution, was obtained.

CONCLUSIONS: NIRS seems suitable for the detection of a transiently impaired cerebral oxygenation under state of pronounced MA in infants with infantile hypertrophic pyloric stenosis. Correction of MA led to normalization of c-rSO2 . NIRS technology constitutes a promising tool for optimizing perioperative management, especially in the context of a possible diminished neurodevelopmental outcome after pyloromyotomy.