Patient Blood Management Guidelines: Module 2

Perioperative

Contents

4 Anaesthesia and patient blood management

4.2 Neuraxial and other major regional techniques compared with general anaesthesia

A systematic review found that neuraxial block reduced requirement for transfusion of two or more units of RBCs by about 50% (p <0.001; OR=0.50, 95%CI: 0.39, 0.66), and that there was a similar reduction for postoperative bleeding that needed transfusion (OR=0.45; 95%CI: 0.29, 0.70).275 Likewise, a meta-analysis found that neuraxial block reduced estimated blood loss by approximately 100–200 mL (p <0.001).276

Choice of anaesthesia technique for total hip arthroplasty should take account of the potential benefit of regional techniques with regard to blood conservation.

Reduced blood loss under neuraxial block is associated with lower arterial and central venous pressures, with spontaneous ventilation, and reduced wound venous pressures.277–280

Orthopaedics is the specialty in which there is the most reliable evidence for neuraxial block in reducing surgical bleeding. Blood loss for total hip joint replacement (THJR) can be reduced by an average of 275 mL281 or 30–40%.282 Neuraxial block also reduced blood loss during hip fracture repair by 85 mL (95% CI: –162, –9), although there was significant heterogeneity.283 Similarly, neuraxial block with and without general anaesthesia for selected spinal column surgery has also been associated with reduced blood loss.277,284 There is also evidence that lumbar plexus block reduces intraoperative (22%; 310 mLvs 617 mL) and total (45%; 712 mL vs 1074 mL) blood loss during THJR.285,286

Although there is less evidence for the choice of anaesthesia having a significant effect on perioperative bleeding in other types of surgery, anaesthetists should be aware of the possible benefits of regional anaesthesia, TIVA and spontaneous ventilation in reducing blood loss.

Among others, several trials suggest that many previously identified benefits of neuraxial technique may be largely historical, with purported major benefits of neuraxial block having been eroded by progressive improvements in surgical, anaesthetic and perioperative care.287–289 However, the previously identified intraoperative physiological effects of neuraxial techniques on blood loss might be expected to persist in at least some surgical populations. On the other hand, data heterogeneity was common in the meta-analyses,287–289 and other practice changes, such as less tolerance of hypotension, may reverse some mechanisms, such as lowered central venous pressure, that are responsible for reducing blood loss.

The evidence for neuraxial anaesthesia reducing transfusion is also present, but should be considered in the context of current blood management. A meta-analysis reported a significant reduction for the surgical population as a whole (a heterogeneous group).275 A study reporting total hip arthroplasty found that neuraxial anaesthesia reduced the transfusion rate to 12%, from 33% with general anaesthesia (OR 0.26, 95% CI: 0.06 to 1.05, p <0.001). Another study found that neuraxial anaesthesia was associated with an OR of 0.646 for needing transfusion.290 However, the results of these studies should be interpreted with caution, given the more restrictive transfusion practices that have developed since much of the research was undertaken. Equally, the implementation of other blood conservation strategies may reduce or negate the illustrated benefits. Despite the limitations of these data, a reduction in surgical bleeding could be expected to reduce transfusion in at least a subgroup of patients.