We would hypothesis that pre-operative fluid loading improves cardiac output and oxygen delivery, but to levels below “supranormal” levels [3,5,34], and this is associated with improved organ perfusion and function click this [3,5,34], fewer surgical complications [35] and fewer adverse events, lower post-operative morbidity, and these factors contribute to the shorter length of stay in hospital after surgery. The magnitude of reduction in hospital length of stay is similar to that seen in other optimisation studies [5,9-11]. It should be noted that this study, and the pre-optimisation literature, appears to contradict the evidence base for intra-operative fluid restriction, which has appeared more recently [15-19]. However, the apparent discrepancy between these two bodies of evidence may be less difficult to reconcile than it appears.

There are seven randomised studies in the literature on fluid restriction and of these only three show benefit [36]. Evidence from the first study of fluid restriction strategies suggests that restricting day of surgery fluid intake from approximately 6,200 ml (of which 5,388 ml were IV) to approximately 3,700 ml (of which 2,740 ml were IV) may be beneficial in terms of complications [15]. Whereas, the current study, and many of the studies cited in the pre-operative optimisation literature, utilise peri-operative fluid loads of 3,000 to 4,000 ml [5]. In studies of fluid restriction, a range of a “liberal intra-operative fluid regimens” from 2,750 to 5,388 ml compared with 998 to 2,740 ml for the “restrictive fluid regimen”[36].

This may suggest that “restrictive fluid regimens” may not actually differ that significantly from optimization strategies in terms of fluid volume. The difference that may explain these two apparently contradictory strategies may relate to either the timing of the fluid administration (early preoperative fluid loading being beneficial and late post-operative fluid overloading being harmful) or related to the achievement of “supranormal” targets. In the Noblett study, which utilised an intra-operative fluid optimisation regime, a significant Cilengitide majority of the fluid administration occurred in the first 40 minutes of surgery [9]. Therefore, there could be an argument that we should target early (pre- and early intra-operative) fluid loading/optimisation and then move to target late (end of surgery) active fluid restriction to avoid post-operative fluid overload and late complications. These bodies of evidence may, therefore, be complementary and not contradictory [37].If this reduction in hospital length of stay can be replicated in a larger study then this finding will have a major impact on service delivery and resource allocation.