Post-operative
Post-operative measures for Witness patients consists of standard
post-operative cardiac care with additional considerations. From the
literature, avoidance of hypertension and the maintenance of
normothermia is key, as is the use of paediatric or low-volume blood
bottles for sample collection26,52. Further to this,
as can be expected, it is also important to continue the delivery of
adjuncts such as IV iron and desmopressin as necessary to
patients26,52. Tanaka et al. additionally
suggests that Witness patients can be given haemodynamic support for
longer in order to maximise systemic oxygen
delivery26. Mechanical ventilation is one such example
of these measures, however, it has been noted in the literature that
this is not a measure untaken by all clinicians, as no difference was
found in ventilation times in seven comparative studies between
Witnesses vs controls2,44,47-51 (Table 2).
Six of the 11 comparative studies in table 2 which reported the outcome
of blood loss did so differently, making direct comparison
difficult2,20,47,49-51. However, within the studies
themselves, two found that the Witness group experienced significantly
less postoperative blood loss compared to the non-Witness control
(Witness vs non-Witness: 466.8 vs 843ml, p=0.000144;
312±141 vs 721±619ml, p<0.0549). This may be
explained by more careful surgery and the blood conserving strategies
discussed in the studies. Binder et al. investigated different
transcatheter aortic valve replacement (TAVR) techniques and concluded
the use of transfemoral TAVR decreased blood loss when no transfusions
were given42. Taken together, the results suggest that
Witnesses do not have more postoperative blood loss than non-Witnesses,
and may even have better outcomes due to strategies employed.