Impact of Delayed Arterial Cord Blood Sampling for Lactate Assay

Abstract

Background: Umbilical cord sampling at delivery provides important data on the newborn’s metabolism. Objective: To evaluate the impact of delayed sampling on arterial cord blood lactate values. Methods: Observational study of 168 consecutive deliveries at a tertiary teaching hospital. Arterial cord blood lactate was determined with a test strip method on paired samples obtained immediately and 5–30 min after birth. At least 90 paired measurements were necessary to show a difference in lactate levels of ≥0.5 mmol/l between the first and second samples. Lactate levels according to the time interval between birth and sampling. Results: One hundred and two paired samples were available for analysis. The lactate value was always higher in the second sample than in the first. Lactate levels increased linearly with time, by 0.062 mmol/l per min. The degree of increase was independent of the initial lactate level and the route of delivery. Delayed sampling resulted in abnormal lactate levels in 16% of neonates born with normal lactate levels. Conclusions: Our results show that delayed sampling of arterial cord blood is unreliable for neonatal lactate assay. Cord blood sampling and lactate assay should therefore be performed immediately after delivery.

Arterial Cord Blood Lactate at Birth Correlates with Duration of Pushing Efforts

“…Delayed cord clamping [22] as well as delayed sampling or analysis of the cord blood could result in falsely elevated lactate levels [9] . In the present series, all the cords were double clamped and sampled immediately at delivery.…”

“…It is difficult to compare lactate measurements performed with different meters and different calibrations. Lactate levels vary according to the mode of delivery [1] and to sampling and analysis conditions [1,[7][8][9] . Thus, a cutoff should be determined in each institution.…”

“…The primary outcome, which determined the sample size of the series, was to evaluate the variations of arterial cord blood lactate according to the delay between birth and sampling [9] . In the present study, we focus on the relationship between arterial cord blood lactate and the duration of pushing efforts.…”

“…Abnormal lactate was defined by levels 1 6 m M , corresponding to the 95th percentile of the distribution in our department [9] .…”

Physiology and Development of the Term and Preterm Neonate

“…For example, while levels in cord blood [ 411 ] and in neonates are normally increased (mean values, 3.8-4.6 mmol/L) [ 412 , 413 ], the concentration of lactate typically decreases to near adult values within 24 h postnatally (mean 2.08 vs. 1.8 upper limit adult norm) [ 413 ]. Persistently increased serum lactate concentrations suggest increased production (poor perfusion and anaerobic metabolism), hepatic dysfunction, or mitochondrial metabolic defect [ 414 ].…”