Obstetric intra-operative cell salvage: a review of an established cell salvage service with 1170 re-infused cases.

The use of cell salvage during caesarean section has been increasing steadily, although there are concerns relating to cost, a perceived risk of amniotic fluid embolism, and fetal red cell sensitisation. We present observational data from almost a decade of use of intra-operative cell salvage in obstetrics. By the end of this period, we set up cell salvage collection for > 98% of all caesarean sections. From 2008 to 2017, 1170 women have had a re-infusion of cell salvaged blood with no clinical safety concerns; the median (IQR [range]) volume was 231 (154-306 [80-1690]) ml. During this time there has been a marked reduction in the number of women who were transfused allogeneic blood, as well as the amount of blood transfused. In total, 647 (55%) women have had alloimmunisation testing, with two positive cases. Quality control data indicate that the quality of blood processed from partial first bowls is no worse than that from full bowls. We discuss the costs of providing this service with regard to: staffing costs; single suction; leucodepletion filters; selectivity in the processing of collected blood; and the use of partial first bowls.

Obstetric intra-operative cell salvage and maternal fetal red cell contamination.

BACKGROUND: The significance of fetal red blood cell (RBC) contamination in obstetric intra-operative cell salvage is not fully known. It is unclear if we re-infuse a larger volume of fetal RBCs into the maternal circulation than the amount that occurs secondary to transplacental haemorrhages is unclear. We also do not know if there is a critical volume required to cause alloimmunisation or if larger volumes increase the risk. OBJECTIVES: The aim of this study is to provide data on the level of fetal RBC contamination in the maternal circulation prior to delivery and immediately post-partum and to compare these levels to those found in processed cell-salvaged blood. METHODS: In the first part of this study, we quantified the levels of fetal RBCs circulating in women immediately prior to delivery. This was then repeated with a separate group measuring the levels of fetal RBCs pre- and post-delivery. RESULTS: We found that 37% of women had fetal cells detected in their circulation, median 0·00 mL (IQR 0-0·24; average 0·3 mL, maximum 4·56 mL). Fetal RBCs were present pre-delivery (maximum 0·66 mL) in 16% of women, increasing to 53% post-delivery (median 0·66 mL; IQR 0·22-2·20, maximum 21·20 mL). CONCLUSIONS: We have shown that fetal RBCs are present in the maternal circulation throughout pregnancy and that the volumes are comparable to that obtained from intra-operative salvage, with contamination amounts of up to 19 mL. At the Royal Cornwall Hospital, our experience and evidence supports offering intra-operative salvage to all women, and we have not noted an increase in antibody formation, compared to allogeneic transfusion.

Is cell salvaged vaginal blood loss suitable for re-infusion?

BACKGROUND: Haemorrhage is one of the commonest causes of maternal critical care admission. Cell salvage used during caesarean section can contribute to a reduction in allogeneic blood consumption. This study sought to provide a practical method to salvage blood lost after vaginal delivery and a description of the constituents before and after washing. METHODS: Blood lost after vaginal delivery was collected from 50 women and washed in a cell salvage machine. No blood was re-infused to any patient in this study. The following measurements were made pre- and post-wash: haemoglobin (haematocrit), alpha-fetoprotein, albumin, lactate dehydrogenase, plasma free haemoglobin, heparin concentration, fetal red cells and identification of bacterial species and colony-forming units (cfu). RESULTS: Median haemoglobin concentration post-wash was 15.4 g/dL. Alpha-fetoprotein, lactate dehydrogenase and albumin concentrations were significantly reduced post-wash (<1 KU/L, 183 IU/L, 0.011 g/L, respectively; P <0.001). Median fetal red cell level post-wash was 0.15 mL [range 0-19 mL]. Median bacterial contamination concentration post-wash was 2 cfu/mL, with a median total count of 303 cfu. CONCLUSIONS: Vaginal blood can be collected efficiently with little disruption to patient management. The amounts of haemolysis and washout of non-red cell blood components are consistent with results in our cell salvage quality assurance programme for caesarean section and non-obstetric surgery. Although bacteria are detectable in all the post-wash and post-filter samples, the median residual contamination is similar to that found with cell salvage in caesarean section, and if re-infused would result in a circulating bacteraemia of <1 cfu/mL; this is similar to that seen with dental procedures (0.3-4.0 cfu/mL) and is thought to be clinically insignificant.

Intraoperative cell salvaged blood as part of a blood conservation strategy in Caesarean section: is fetal red cell contamination important?

BACKGROUND: Cell salvage is used in obstetric surgery as part of a blood conservation strategy in our Trust. This carries a theoretical risk of amniotic fluid embolism and also a risk of fetal red cells being present in the re-infusion, resulting in alloimmunization. In this study, we attempted to quantify the risk of antibody formation from re-infusion of autologous blood after Caesarean section. METHODS: Women presenting for elective Caesarean section were routinely requested to consent for collection of blood by cell salvage, using one suction device. If an adequate volume of blood was collected, it was processed and, if clinically appropriate, re-infused via a leucodepletion filter. Women who received a re-infusion were followed up to test for antibody formation. RESULTS: Seventy women consented for re-infusion and follow-up. The median volume re-infused was 324 ml (range 118-1690 ml). The median fetal red cell contamination was 0.8 ml (range 0.2-12.9 ml). All re-infusions were given without adverse clinical signs. No antibodies were detected in 48 follow-up samples. One positive anti-S antibody was detected. CONCLUSIONS: The implementation of a blood conservation strategy which includes the use of intraoperative cell salvage appears safe and can contribute to a reduction in the number of blood transfusions to the obstetric population. We remain uncertain of the significance of fetal red cell contamination.

The dose-effect relationship for morphine and vomiting after day-stay tonsillectomy in children.

A dose-response curve for intravenous morphine and vomiting was investigated in children having day-stay tonsillectomy. A retrospective chart review was performed for the 164 children fulfilling the inclusion criteria. Morphine (mean 0.09 mg/kg SD 0.05) was used in 108 children in the perioperative period and a further 56 children were given no opioid. Fifty-five of these 164 children vomited and 20 children required an overnight stay in hospital because of vomiting. The probability of vomiting or overnight stay in hospital was related to morphine dose (by logistic regression). The overall probability of vomiting after morphine 0.1 mg/kg was 50% and the probability of admission for vomiting with this dose was 10%. Pharmacodynamic parameter estimates for postoperative vomiting were P0 (the baseline probability of vomiting, with no opioid) 0.115, Pmax (the maximal probability of vomiting due to morphine) 0.997, ED50 (morphine dose that induces an effect equivalent to 50% of the logit Pmax) 0.18 mg/kg. Parameter estimates for overnight stay because of vomiting after morphine administration were P0 0.038, Pmax 0.999, ED50 0.369 mg/kg. Satisfactory postoperative analgesia in children has been reported with morphine 0.05 to 0.15 mg/kg. Doses above 0.1 mg/kg are associated with a greater than 50% incidence of vomiting. Our data suggests that lower doses of morphine are associated with a decreased incidence of emesis after tonsillectomy in children.

Anaesthetic management of parturients with the antiphospholipid syndrome: a review of 27 cases.

A description of antiphospholipid syndrome (APS) and associated maternal and fetal complications is presented along with a review of the management at National Women's Hospital (NWH), Auckland, of 27 pregnancies complicated by APS. Because the obstetric outcome for parturients with APS continues to improve, anaesthetists are more likely to become involved in their management. It is recommended that policies and protocols are implemented to avoid unnecessary denial of regional anaesthesia arising from confusion about any parturients anticoagulation status.

Subdural or epidural? Confirmation with magnetic resonance imaging.

An epidural performed for obstetric analgesia was initially characteristic of a subdural block but subsequently behaved as a normal epidural. Radiological confirmation of the catheter having been subdural was established by performing a magnetic resonance imaging scan.