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.