Bedside detection of low systemic flow in the very low birth weight infant on day 1 of life

Abstract

We aimed to assess the relationship between the clinical and biochemical parameters of perfusion and superior vena cava (SVC) flow in a prospective observational cohort study of very low birth weight (VLBW) infants. Newborns with congenital heart disease were excluded. Echocardiographic evaluation of SVC flow was performed in the first 24 h of life. Capillary refill time (forehead, sternum and toe), mean blood pressure, urine output and serum lactate concentration were also measured simultaneously. Thirty-eight VLBW infants were examined. Eight patients (21%) had SVC flow less than 40 ml/kg/min. There was a poor correlation between the capillary refill time (in all sites), mean blood pressure, urine output and SVC flow. The correlation coefficient for the serum lactate concentration was r = -0.28, p = 0.15. The median serum lactate concentration was 3.5 (range 2.8-8.5) vs. 2.7 (range 1.2-6.9) mmol/l (p = 0.01) in low flow versus normal flow states. A serum lactate concentration of >2.8 was 100% sensitive and 60% specific for detecting a low flow state. Combining a capillary refill time of >4 s with a serum lactate concentration of >4 mmol/l had a specificity of 97% for detecting a low SVC flow state. Serum lactate concentrations are higher in low SVC flow states. A capillary refill time of >4 s combined with serum lactate concentrations >4 mmol/l increased the specificity and positive and negative predictive values of detecting a low SVC flow state.

Management of Hypotension in Preterm Infants (The HIP Trial): A Randomised Controlled Trial of Hypotension Management in Extremely Low Gestational Age Newborns

“…Although there is a significant relationship between cardiac index (cardiac output/body surface area) and capillary refill time in preterm babies, there appears to be only a weak association between capillary refill and systemic blood flow [33]. We previously identified a weak relationship between capillary refill values and simultaneously obtained echocardiographic measures of superior vena cava (SVC) flow [35]. Though the glomerular filtration rate rises rapidly after birth, urine output is low and variable in the first 24 h, the period when preterm infants are most commonly treated for hypotension, making it a less useful measurement.…”

The Association between Multisite Near-Infrared Spectroscopy and Routine Hemodynamic Measurements in Relation to Short-Term Outcome in Preterms with Clinical Sepsis

“…Furthermore, cFTOE was higher during episodes of tachycardia and CRT ≥ 3 s, while renal and mesenteric FTOE values did not differ. Previously, associations were found in neonates between a prolonged CRT and low superior vena cava flow [1,2] and low cardiac index [13] . We cannot offer a clear explanation for not finding different somatic FTOE values during episodes of prolonged CRT and tachycardia, other than the smaller sample and larger physiological variability of somatic NIRS measurements compared with cerebral NIRS measurements [6] .…”

“…In our cohort, FTOE values Data are shown as medians or n. * p < 0.05 compared to FTOE values during the absence of the sign of circulatory failure; ** p < 0.01 compared to FTOE values during the absence of the sign of circulatory failure. clinical signs of circulatory failure and systemic blood flow as assessed by Doppler echocardiography [1,2,10] . Third, sepsis-associated microvascular dysfunction might have influenced the association between routine hemodynamic measurements, which predominantly reflect macrohemodynamics, and NIRS measurements, which might be affected by a disturbed microcirculation [11,12] .…”

“…Although monitoring tissue oxygen delivery is essential to guide adequate treatment during circulatory failure, it is challenging in preterm infants since the possibilities for invasive hemodynamic monitoring are limited. Routine clinical hemodynamic measurements, such as blood pressure and capillary refill time (CRT), are poor predictors of systemic blood flow as estimated by functional echocardiography [1,2] . Biochemical indicators of tissue oxygen delivery, such as…”

Common Hemodynamic Problems in the Neonate

“…Most hypotensive preterm infants have flow in the superior vena cava and/or right ventricular output which are within the normal range [31] . The converse of this is that many infants with low systemic flow have normal blood pressure.…”