Cell salvage in obstetric anaesthesia: is it worth the time and effort?

Nolan McDonnell FANZCA

Staff Specialist, King Edward Memorial Hospital for Women, Perth, Australia

Obstetric haemorrhage remains a leading cause of maternal death throughout the developed world. Whilst intraoperative cell salvage was developed in the 1970s and is in common use in orthopaedic, vascular and cardiac surgery, its use in obstetric situations has been viewed as relatively contraindicated, predominately because of concerns that re-transfused amniotic fluid may be a trigger for the amniotic fluid embolism syndrome.

In the UK there has been a major push towards the use of cell salvage in obstetric cases1. The motivation for this has been an increased demand for blood in the face of a diminishing supply (on the background of concerns over variant Creutzfeldt-Jakob Disease) as well as increasing awareness of the potential risks of allogeneic blood transfusion. This has been endorsed by several groups, including CEMACH, the Obstetric Anaesthetists Association and the National Institute for Clinical Excellence1.

The evidence for the safety of cell salvage in obstetric haemorrhage is predominately derived from case reports and small retrospective case series2. Published cases are relatively few (just over 400) with one documented maternal death in a medically complex patient who received cell salvage without a leucocyte depletion filter (the exact role of cell salvage in this patients death is unclear)3.

The specific risks associated with the use of cell salvage in obstetric haemorrhage are the potential to re-infuse amniotic fluid (and hence trigger the amniotic fluid embolism syndrome), as well as the potential for alloimmunisation of the mother1. The underlying pathophysiology of amniotic fluid embolism has yet to be fully elucidated, whether amniotic fluid is a normal component of the maternal circulation during labour and delivery and whether it is the actual triggering mechanism for the syndrome is still open to debate. A number of steps can be taken to avoid contamination of the salvaged blood with amniotic fluid, including the universal use of leucocyte depletion filters which assist in the clearance of bacterial contaminants as well as clearing some, but not all components of amniotic fluid4.

As cell salvage is unable to distinguish between maternal and fetal blood there is a potential risk of alloimmunisation of the mother. Kleihauer testing of the infused product and the maternal blood can guide management in terms of appropriate anti-D dosing.

Intraoperative cell salvage was introduced into clinical practice at King Edward Memorial Hospital (KEMH) for Women in early 2006 after the purchase of a Haemonetics C5 Cell Saver machine. This hospital functions as a stand alone Women's hospital with no on site ICU or interventional radiology services. It functions as the tertiary obstetric referral centre for a population of over 2 million people spread over the whole of Western Australia. The nearest hospitals with tertiary services are all at least 10 minutes by ambulance and none can provide the necessary mix of obstetric, neonatal, medical and anaesthetic expertise to manage high risk obstetric cases on a regular basis.

With this in mind and given the rising number of complex obstetric cases being managed it was considered that cell salvage would provide a valuable addition to the on site clinical services. As KEMH had no prior experience with cell salvage it was deemed necessary to follow a formal quality assurance process. Twenty five study cases (with no re-infusion) would be performed and assessed prior to the more widespread implementation.

In an effort to avoid contamination with amniotic fluid (and as described by other centres5), two suction devices were used throughout the procedure with one connected to the cell salvage machine and one to the standard wall suction. The cell salvage suction is only utilised pre uterine incision and then post delivery of the baby, after the amniotic fluid has been cleared.

The salvaged and processed blood was assessed with a number of tests. These included the haematocrit, free plasma haemoglobin, alpha feta protein, potassium and Kleihauer tests. A Pall RS1 leucocyte depletion filter was used in all cases. In 9 of the 25 cases there was insufficient blood obtained to conduct washing and processing but these cases provided valuable experience for the theatre staff in the technical aspects of the procedure. In the remaining 16 cases there was an obvious improvement in the quality of salvaged blood as the QA process continued and this process was formally completed in March 2007.

Since this date cell salvaged blood has been re-infused to 11 patients of which 10 were complex obstetric cases. Two patients who refused autologous blood products on religious grounds were subsequently transfused with cell salvaged blood. A further 8 patients had cell salvage performed in the operating theatre but did not lose sufficient blood for a transfusion to be required. The volume of blood re-infused ranged from 242 ml to 1000 ml, with a mean of 520 ml. The haemoglobin in the transfused blood has ranged from 146 to 182 g/l with a haematocrit of 0.47 to 0.56. There have been no adverse clinical consequences in any of the patients to date.

Currently we provide a cell salvage service as an in hours service only, with out of hours cases only able to be performed if the technician on duty or on call is formally accredited to operate the cell salvage machine. Requests for cell salvage are reviewed by an anaesthetist and technician to ensure that the indication is valid. The majority of requests to date have been in patients refusing blood products who have risk factors for haemorrhage (eg JW patients with placenta praevia) or in patients with a greatly increased risk of haemorrhage, for example patients with a known/presumed morbidly adherent placenta.

In conclusion, intraoperative cell salvage has been utilised at least monthly at KEMH since its introduction. It has proven itself to be a valuable resource especially in patients who have refused traditional blood products. The introduction has been at considerable expense in terms of purchasing the machine, training of staff and consumables required. Establishing this new service in a "non-traditional" cell salvage environment has been worth the extra time and effort especially when considering the clinical isolation in which this hospital operates
1. Allam J, Cox M, Yentis S M. Cell salvage in obstetrics. Int J Obstet Anesth 2008; 17: 37-45.
2. Catling S, Joels L. Cell salvage in obstetrics: the time has come. Bjog 2005; 112: 131-132.
3. Oei SG. Cell salvage: how safe in obstetrics? Int J Obstet Anesth 2000; 9: 143.
4. Catling S J, Williams S, Fielding A M. Cell salvage in obstetrics: an evaluation of the ability of cell salvage combined with leucocyte depletion filtration to remove amniotic fluid from operative blood loss at caesarean section. Int J Obstet Anesth 1999; 8: 79-84.
5. Rainaldi M P, Tazzari P L, Scagliarini G, Borghi B, Conte R. Blood salvage during
caesarean section. Br J Anaesth 1998; 80: 195-198.