The effect of colloid and crystalloid preloading on thromboelastography prior to Cesarean delivery

Abstract

Purpose: Fluid preloading with colloids reduces hypotension after spinal anesthesia for Cesarean delivery more effectively than crystalloids. However, the effects of fluid preloading regimens on coagulation in pregnant patients remain unresolved. The aim of this study was to compare the effects on coagulation of fluid preloading with 6% hydroxyethyl starch (HES) and lactated Ringer's (LR) solution using thromboelastography (TEG) with kaolin-activated whole blood in healthy pregnant patients prior to spinal anesthesia for Cesarean delivery. Methods:After obtaining Ethics committee approval, 30 parturients were prospectively randomized prior to spinal anesthesia for elective Cesarean delivery to receive fluid preloading with either 1500 mL LR or 500 mL 6% HES over 30 min. Thromboelastography was performed immediately prior to and after fluid preloading. Standard TEG parameters were analyzed in terms of r time (min), k time (min), α angle (degrees) and maximum amplitude (mm).Results: Group HES had statistically significant longer reaction times (r) and clot formation times (k) after fluid loading compared to baseline values (P < 0.05 respectively), although these post-fluid loading TEG parameters remained within a normal reference range. No significant differences in TEG values were seen after preloading within the LR group. Conclusion:Fluid preloading with 500 mL 6% HES in healthy parturients produced mild coagulation effects, as measured with TEG, prior to spinal anesthesia for Cesarean delivery. No significant effects on coagulation with TEG were observed following preloading with 1500 mL LR.

Assessment of coagulation in the obstetric population using ROTEM® thromboelastometry

“…17,19 Haemodilution with colloids may interfere with fibrinogen assays which could have significance in obstetric haemorrhage. [20][21][22] More importantly ROTEM Ò does not allow accurate analysis of primary haemostasis which is central to clot formation, the exact mechanisms of which are poorly understood in pregnancy. 17 Venous thrombosis incidence in pregnancy is remarkably low considering the magnitude of the coagulation factor concentration increase and this probably reflects a 'balancing act' between hypercoagulability and poorly understood counteracting mechanisms.…”

Use of thromboelastography to guide thromboprophylaxis after caesarean section

“…Patients received on average 1495 mL of compound sodium lactate and, although this was not controlled, TEG has demonstrated that lactated Ringer's solution in a volume up to 1500 mL does not affect coagulation before spinal anaesthesia for CS. 28 Other potentially confounding variables were neuraxial dose, oxytocin dose, the time between CSE placement, administration of heparin and the surgical intraoperative time, although the latter was always complete within the hour between heparin administration and first sample. Low-and moderate-risk patients were recruited and there may have been a difference in the coagulation profiles of these groups, but the use of heparinase modified TEG, which specifically reverses the effect of heparin, allows patients to act as their own control.…”

Hetastarch co-loading is as effective as pre-loading for the prevention of hypotension following spinal anesthesia for cesarean delivery

“…[19][20][21][22] A mild anticoagulant effect (within a normal reference range as measured by thromboelastography) was observed after a 500-mL hetastarch pre-load in healthy parturients presenting for elective cesarean delivery. 22 Exposure to hetastarch has been found to be an independent risk factor for pruritus (odds ratio 1.78; 95% confidence interval 1.23-2.58). 21 The risk of anaphylactoid/anaphylactic reaction following hetastarch administration is extremely rare with an estimated incidence of 0.007-0.047%.…”