Pre-operative
The optimisation of patient care is imperative in order to achieve good medical practice, and is especially important to consider for patients with additional requirements, such as Witness patients39. Therefore, it is important for both clinicians and service providers to assess whether they are adequately equipped to provide Witnesses patients with the best care12. A number of complex cardiac surgery case reports demonstrate this and express the importance of referral to tertiary centres12,27. This was especially noted in a case report by Papalexopoulou et al., where a Witness patient was eventually operated on for an aortic dissection following previous assessment at two other centres12.
A further factor that could be assessed at the pre-operative stage for Witness patients is the relative risk of patients requiring a blood transfusion during surgery. A number of tools have been developed to aid with this, such as the use of the ‘Transfusion Risk And Clinical Knowledge (TRACK) score’, which was utilised by Kim et al. for evaluating Witness patients40, as well as the use of the ‘Transfusion Risk Understanding Scoring Tool (TRUST)’ utilised on Witness patients by Moraca et al. 4.
There are a number of other standard pre-operative steps which clinicians must undertake in order to appropriately manage Witness patients. One of the most important and frequently studied in the literature is the optimisation of pre-operative haemoglobin levels through the use of Erythropoietin (EPO) and either oral or IV iron3,26,41-43. The use of EPO in particular was explored by Duce et al. in a matched cohort study, which compared patients who were treated with EPO and declined blood transfusion, to controls who did not receive EPO at all8. The study noted that there were no clinically significant differences in outcomes measured between the two cohorts, demonstrating the positive impact of EPO for patients refusing transfusion and hence supports its use for Witness patients8.
11 comparative studies discussing outcomes between Witnesses and non-Witnesses were found2,15,20,44-51 (Table 2) and these often gave agents to increase the preoperative Hb. This varied between studies and makes comparison more challenging. Six of the studies reported preoperative Hb levels44-47,50,51, with three of these showing higher levels for the Witness group (Witness vs non-Witness: 13.7 vs 12.8g/dL, p=0.0144; 13.9 vs 12.3g/dL, p<0.000146; 13.6 vs 12.9g/dL, p=0.0147). Similar preoperative haemoglobin levels were reported in Witness only studies (12.1±1.352, 13.918, 14.129 and 14.5g/dL53). Postoperative haemoglobin levels were reported in five of the 11 comparative studies, with three a significantly higher result in the Witness group (Witness vs non-Witness: 10.8 vs 9,9g/dL, p=0.00344; 11.7 vs 9.8g/dL, p<0.000146; 11 vs 10g/dL, p=0.00347). A non-comparative study reported a similar postoperative haemoglobin level in a Witness population (10.1±1.5g/dL)52. A study in Witnesses undergoing non-cardiac surgery found an increased risk of morbidity and mortality when haemoglobin levels were below 8g/dL54, with another study reporting similar outcomes within cardiac surgery55, highlighting the importance of increasing Hb levels preoperatively.