Conclusions
Clinicians should base their decision whether to manipulate perioperative global blood flow on the magnitude of reductions in postoperative morbidities and length of hospital stay rather than upon the assumption that mortality will be reduced. For every 100 patients exposed to the intervention one can expect 13/100 to avoid having complications; 2/100 to avoid renal impairment; 5/100 to avoid respiratory failure; and 4/100 to avoid postoperative wound infection. Patients remain in hospital ~1 day less and there is no increase in harm. This intervention should be considered where the relevant resources are available and implementation will not otherwise harm the patient (for example, delay in definitive care).
A specific limitation of this review is the large number of studies that were published >10 years and the limited amount of data that represent current practice and outcomes. A specific group that particularly merits further study, in view of the high incidence of mortality and morbidity and limited available data, is patients undergoing emergency surgery.
Future studies in this area should test an explicitly framed hypothesis, be adequately powered (and preferably multicentre), methodologically rigorous, and include blinded interventions where possible. Reporting of outcomes should be standardized (to allow comparison between studies and to facilitate the conduct of future meta-analyses) and inclusive (morbidity, health status, and resource usage).