New Australian study shows more IV fluids during surgery is beneficial

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A mainstay of hospital treatment after major surgery – the intravenous (IV) saline drip – could be revolutionised for millions of patients worldwide following the findings of new international research led by Australian anaesthetists. More than 300 million people worldwide undergo major surgery each year, and anaesthetists have fiercely debated whether to give patients more or less IV fluid during surgery and in the days following. In the last 10 to 15 years there was a move to restrict, by almost a half, the amount of fluids given to prevent complications. While small studies had previously indicated that limiting IV fluids was beneficial for patients undergoing abdominal surgery, the six year, randomised controlled RELIEF trial (or restrictive versus liberal fluid therapy in major abdominal surgery trial) proved otherwise.

The trial results, Restrictive Versus Liberal Fluid Therapy for Major Abdominal Surgery were published in the New England Journal of Medicine (available on CKN) showed that IV fluid restriction was linked to a greater risk of severe wound infection.

All patients who undergo major surgery receive IV fluids to counteract extended periods of not being able to drink or eat before and after surgery, and also to restore the circulation if there is excessive bleeding. Major abdominal surgery for conditions such as bowel, pancreatic and stomach cancer is associated with many risks, and the personal, social and economic consequences of postoperative complications are substantial with a third of patients requiring intensive care. For older people and those with pre-existing medical conditions, complications can be life-threatening or otherwise lead to permanent disability. 

In the trial half the patients studied were given a limited amount of IV fluid while the other half were given larger amounts. All study participants were followed up to a year after their operation. The study found that patients had fewer complications and recovered more quickly after their operation if they were given more IV fluids rather than less. The study involved 3,000 abdominal surgery patients in 47 hospitals in seven countries including Australia, the US, Canada, New Zealand and the UK, and found the restrictive practice led to a "doubling" of severe kidney damage. 

"These are people that actually have what we would label as quite severe renal damage, so much so that a proportion of them had to have dialysis in the first few weeks or months after surgery," said lead investigator Prof. Paul Myles, director of anaesthesia and perioperative medicine at The Alfred Hospital and Monash University.

“Over the past 15 years many small studies have suggested positive benefits with a more restrictive fluid regimen in abdominal surgery, with faster return of bowel function, fewer complications, and shorter hospital stay. But other experts have disagreed, worried this this may lead to dehydration, kidney damage and delayed recovery after surgery,” Prof. Myles explained. The results contradict the findings of these smaller studies. "We have certainly dispelled the belief that [a restrictive fluid regimen] improves disability-free survival, so therefore it's not helpful. The results of this international trial were clear-cut and very reassuring - a more liberal amount of IV fluids protects against kidney damage and reduces the risk of wound infection after surgery." Myles said.

The trial also showed patients had fewer complications and recovered more quickly after their operation if they were given more IV fluids rather than less.

The impact of the findings is expected to be immediate and immense for hospitals, said Myles. “We’ve now got compelling evidence to impact practice around the world,” he said. “This is a very definitive result but there will of course continue to be cases where some patients will require a bit more or a bit less IV fluid depending on their individual needs.”

The Alfred in Melbourne, where an estimated 28,000 operations are performed every year, will be among the first to implement the evidence-based change in practice.