Effects of Caffeine on Splanchnic Oxygenation in Preterm Infants

Objective The aim of this study is to assess the effects of administering 20 mg/kg loading dose of caffeine citrate intravenously on splanchnic oxygenation in preterm infants. Study Design The infants with a gestational age (GA) of <34 weeks who were administered with a 20 mg/kg intravenous loading dose of caffeine citrate within 48 hours after birth were investigated prospectively. Regional splanchnic oxygen saturation (rsSO2) and splanchnic fractional tissue oxygen extraction rate (sFTOE) were measured using near-infrared spectroscopy before caffeine infusion, immediately after caffeine infusion and 1, 2, 3, 4, and 6 hours (h) after dose completion; postdose values were compared with predose values. Results A total of 41 infants with a mean GA of 29.2 ± 1.6 weeks and birth weight of 1,315 ± 257 g as well as postnatal age of 32.2 ± 10.8 hours were included in the study. rsSO2 significantly reduced from 63.1 to 57.5% immediately after caffeine infusion, 55.1% after 1 hour, and 55.2% after 2 hours with partial recovery at 3-hour postdose. sFTOE increased correspondingly. Conclusion Caffeine reduces splanchnic oxygenation and increases splanchnic oxygen extraction for at least 2 hours with partial recovery to predose levels at 3-hour postdose.

Regional Tissue Oxygen Extraction and Severity of Anemia in Very Low Birth Weight Neonates: A Pilot NIRS Analysis

Objective Anemia causes blood flow redistribution and altered tissue metabolic behavior to sustain homeostatic oxygen consumption. We hypothesized that anemia severity would correlate with increased regional fractional tissue oxygen extraction among premature neonates. Study Design Regional oxygen extraction was calculated using pulse oximetry and near-infrared spectroscopy data among neonates <1,250 g during their first 10 postnatal days. Oxygen extraction was assessed for correlations with raw hematocrit levels and following grouping into hematocrit quartiles. Results Twenty-seven neonates with gestational age 27 ± 2 weeks and birth weight 966 ± 181 g underwent 116 hematocrit determinations. Cerebral and flank oxygen extraction inversely correlated with hematocrit (cerebral r = −0.527, p = 0.005; flank r = −0.485, p = 0.01). Increased cerebral oxygen extraction was observed for the lowest three hematocrit quartiles (Q1 0.26 ± 0.08, p = 0.004; Q2 0.24 ± 0.09, p = 0.01; Q3 0.25 ± 0.09, p = 0.03; all compared with Q4 0.18 ± 0.10). Increased flank oxygen extraction occurred for the lowest two quartiles (Q1 0.36 ± 0.12, p < 0.001; Q2 0.35 ± 0.11, p < 0.001; compared with Q4 0.22 ± 0.13). Splanchnic oxygen extraction demonstrated no similar correlations. Conclusion Increases in tissue oxygen extraction may indicate early pathophysiologic responses to nascent anemia in premature neonates.