Serum lactate
Serum lactate has been studied as a strong biochemical marker of tissue
hypoperfusion and hypovolemia in patients with obstetric haemorrhage;
increased lactate concentration may indicate hypovolemic shock before
traditional markers such as haemoglobin concentrations, and vital signs.
There are portable lactate analysers that require 15-50 µL of blood and
take approximately 60 seconds to process which makes it easier for the
bedside monitoring by capillary lactate. Our research revealed that the
bedside serum capillary lactate as a point-of-care test can
differentiate the severe group from non-severe for this reason allows
quick during lactate-guided recusation and probably reduce risk of
thrombophlebitis that may result from venous sampling. Previously it was
reported that venous lactate of 2.6 mmol/dl at the diagnosis of
postpartum haemorrhage may be a good predictor for severe haemorrhage
(sensitivity of 0.85 and specificity was 0.76) (10). For the case of
capillary lactate, these outpoint seem to be higher, this may be a
multifactorial effect including lactate detection method and
compensatory mechanisms of peripheric blood constriction to guarantee
blood flow to vital organs. We obtained the cut point of 4.3 mmol/dl at
30 min had good performance (AUC 0.75), with sensitivity 0.85,
specificity 0.62 AUC 0.75. At the diagnosis and 15 min we obtained
higher cut points but with low performance.