101 Effect of oxygen therapy in early neotnatal life on capillary microcirculation and blood pressure in low birth weight infants

BackgroundLow birth weight (LBW) is a risk factor for adult essential hypertension, diabetes mellitus, obesity and cardiovascular disease mortality in later life. Individuals with history of LBW have many abnormalities in their blood vessels including a reduction in microvascular density or rarefaction. Capillary rarefaction (CR) is a hallmark of essential hypertension and evidence suggests that CR is a primary structural abnormality that precedes the onset of the rise in blood pressure (BP) as it is found in normotensive individuals at high risk of developing hypertension. We recently found that LBW infants have higher and not lower capillary density at birth. We hypothesised that LBW infants will undergo significant CR in early life triggered or exaggerated by oxygen therapy.MethodsWe studied 26 LBW infants and 14 normal birth weight infants (NBW) as controls. Of the LBW infants, only 10 received oxygen therapy. We used a handheld video capillaroscopy system (HVCS) to measure functional or basal (BCD) and structural or maximal capillary density (MCD) on day 1, 5, and 10, and after 40 weeks adjusted for the gestational age in preterm LBW infants. Blood pressure was measured at each visit using Welch Allyn VSMTM 300 monitor.ResultsAt birth, the NBW infants had significantly lower BCD (difference −9.3 cap/area, 95% CI: −1.5 to −17.1, p=0.021) and MCD (difference −12.6 cap/area, 95% CI: −1.5 to −21.7, p=0.025) compared to the LBW infants. LBW oxygen group had a significantly lower SBP (mean difference −9.5 mmHg, 95% CI: −1 to −19, p=0.047), DBP (difference −13 mmHg, 95% CI: −4 to −22, p=0.009). At 40 weeks old, the LBW oxygen group showed a significant reduction in BCD (difference −19.3 cap/area, 95% CI: −9 to −30, p=0.003) and MCD (difference −22 cap/area, 95% CI: −8 to −36 p=0.007). Similarly the LBW non-oxygen group had a significant reduction in BCD (difference −29 cap/area, 95% CI −17 to −41 p