Increasing Global Blood Flow Before Surgery May Improve Outcomes

The use of fluids to increase blood flow before major surgery, with or without inotropes or vasoactive drugs, does not reduce mortality but may be associated with fewer complications and shorter hospital stays, according to the findings of an intervention review conducted by the Cochrane Anaesthesia Group.¹

Increasing whole body blood flow and oxygen delivery perioperatively has been suggested to reduce mortality, morbidity, and costs involved with major surgery. To determine if the available evidence supports these suggestions, researchers analyzed randomized controlled trials involving patients aged 16 years and older who received fluids targeted to increase global blood flow beginning up to 24 hours before surgery and stopping up to 6 hours after surgery. “Targeted to increase blood flow” was defined by explicit measured goals, such as cardiac index, oxygen delivery, oxygen consumption, stroke volume, mixed venous oxygen saturation, oxygen extraction ratio, or lactate, that were more often met in treatment groups than in control groups.

In total, 31 studies involving 5292 participants satisfied inclusion criteria and were analyzed. Overall, there were no statistically significant differences in mortality between study groups. In the control group, 282 (10.8%) of 2615 patients died, compared with 238 (8.9%) of 2677 patients who died in the treatment group (P=0.18). When inverse variance or Mantel-Haenszel random-effects models were used, however, the intervention group was found to have better outcomes than the control group, suggesting that the results were sensitive to analytical methods. When studies with methodological limitations were withdrawn, researchers found that increasing global blood flow significantly reduced the occurrence of renal failure (relative risk [RR], 0.71), respiratory failure (RR, 0.51), and wound infection (RR, 0.65).

Overall, the intervention was associated with a reduction in the number of complications (RR, 0.68). In addition, patients who received the intervention spent an average of 1.16 fewer days in the hospital. In practical terms, these results mean that for every 100 patients who are given fluids to increase global blood flow, 13 will avoid a complication, 2 will avoid renal impairment, 5 will avoid respiratory failure, and 4 will avoid a postoperative wound infection.

There is insufficient evidence to recommend that this intervention be widely implemented. However, the evidence suggests that this intervention reduces morbidity and duration of hospital stays.

Pertinent Points:
- Increasing global blood flow before surgery is associated with a shortened hospital stay and a reduced risk of certain complications.
- Mortality is not affected by increasing blood flow before major surgery.

References:

1. Grocott MPW, Dushianthan A, Hamilton MA, et al. Perioperative increase in global blood flow to explicit defined goals and outcomes following surgery. Cochrane Database System Rev. 2012;11:CD004082. DOI: 10.1002/14651858.CD004082/pub5.