Volume therapy in obstetrics.

Abstract

Editor, Marx et al.1 of the Scientific Medical Societies in Germany are to be congratulated for their diligent effort to show us what we know and – maybe even more importantly – what we don’t know about intravascular volume therapy in adults. Although they show that there is good evidence on how to detect and monitor intravascular hypovolaemia, clinical practice on how to treat it is debatable. Both the Guidelines and the excellent accompanying Commentary by De Robertis et al.2 show nicely that the current debate is caused partly by the lack of large long-term outcome trials in the perioperative setting, the (mis-)use of older high-molecular weight hydroxyethyl starch (HES) solutions and by the ‘methodological deficiencies and contradicting results’1 of the large trials in the intensive care setting. We fully agree with the authors that more trials are needed with appropriate enrolment, targets and monitoring as well as recognition of indications and contraindications. However, one aspect we disagree with is the recommendation 4a-4. Maternal hypotension is a frequent complication during spinal anaesthesia in obstetrics, with reported incidences of about 70%.3 Hypotension in this setting is associated with nausea, vomiting, dizziness, unconsciousness, pulmonary aspiration as well as reduced placental perfusion and reduced oxygen supply to the unborn child.4 Vasopressors, despite being a well established treatment, are associated with adverse effects such as reduced maternal heart rate and cardiac output, potentially resulting in reduced perfusion of the uteral-placental system and foetal hypoxia and acidosis.5 One successful way to reduce the need for vasoconstrictors is by infusing fluid boluses. Fluid infused before (pre-load) and during (co-load) induction of spinal anaesthesia has frequently been shown to significantly reduce the need for or dose of vasopressors. Several trials and a recent meta-analysis by Ripollés-Melchor et al.6 have shown a significant reduction in hypotension when using HES 130 in combination with crystalloids in this situation. The only double-blind randomised controlled trial in this setting compared 500 ml HES and 500 ml crystalloid with 1000 ml crystalloid and it showed significantly reduced risks of symptomatic hypotension, nausea and vomiting without any effect on foetal outcome, coagulation, kidney function, bleeding or transfusion requirements when using the HES/crystalloid combination.6 A trial from Sümpelmann et al.,7 in 1130 children undergoing general surgery, concluded that HES 130 was ‘safe in neonates and small children’, while Van der Linden et al.8 showed, in 1495 children undergoing cardiac surgery, no differences in outcome with HES in comparison with human albumin. As Mercier et al.4 could not detect any HES molecules in umbilical cord blood, it is unlikely that the unborn child even has contact with this drug. From this point of view, a grade A recommendation to restrict use of colloids (HES) in obstetrics to emergency situations only because of ‘lack of data on child safety’ is not logical. At least a grade ‘0’ (may), or even grade ‘B’ (should), recommendation for the use of HES in combination with crystalloids as a pre-load or co-load along with spinal anaesthesia in obstetrics would reflect the current literature and clinical practice. Acknowledgements relating to this article Assistance with the letter: none. Financial support and sponsorship: none. Conflicts of interest: DC had held lectures for and has received research grants from BBraun, Fresenius Kabi, Grifols and LFB Biomedikaments. MJ had held lectures for and has received research grants from Baxter, BBraun, Fresenius Kabi, Grifols and Serumwerk Bernburg, and is a member of the albumin advisory board of Grifols.