Relief Trial : Liberal fluids (?) in abdominal surgical patients

P.S. Myles, R. Bellomo, T. Corcoran et el published results of Relief trial (Restrictive versus Liberal Fluid Therapy in Major Abdominal Surgery) in New England Journal of Medicine.

BACKGROUND

Each year, 310 million surgeries happen world wide. These patients end up getting large amounts of intravenous fluids leading to fluid overload.  A study published in 2003, showed that fluid overload and fluid retention were not beneficial; the numbers of complications that were reported after open colorectal surgery were nearly halved by keeping patients at a near-zero fluid balance. On the other hand, Fluid restriction could increase the risk of hypotension and decrease perfusion in the kidney and other vital organs, leading to organ dysfunction.

Current recommendations for Intravenous-fluid regimens for abdominal surgery have been classified as restrictive (<1.75 liters per day), balanced (1.75 to 2.75 liters per day), and liberal (>2.75 liters per day). Also suggests avoiding
a weight gain of more than 2.5 kg.

TRIAL

This was a a randomized, controlled trial comparing a restrictive intravenous-fluid strategy with a relatively liberal fluid strategy during the perioperative period in 3000 patients at increased risk for complications during major abdominal surgery.

PATIENTS

Adult high risk patients who underwent major abdominal surgery (Duration of at least 2 hours, with expected hospital stay of 3 days). They were considered high risk if age was at least 70 years or had presence of heart disease, diabetes, renal impairment, or morbid obesity.

Patients  were excluded if they were undergoing urgent or time-critical surgery, liver resection, or less extensive surgery (e.g., laparoscopic cholecystectomy) or if they had end-stage kidney failure requiring dialysis.

Total 3000 patients were randomized, restrictive fluid regimen (1501 patients) or a liberal fluid regimen (1499 patients) at 47 centers in seven countries.

INTERVENTION GROUP

A bolus of a balanced salt crystalloid solution was administered at a dose of 10 ml per kilogram of body weight during the induction of anesthesia, followed by a dose of 8 ml per kilogram per hour until the end of surgery.
The perioperative dose could be further reduced after 4 hours if clinically indicated. Dose was calculated at maximum of 100kg for morbidly obese.  Post operatively, fluid was given 1.5 ml per kilogram per hour for at least 24 hours.

RESTRICTIVE GROUP

Designed to provide a net zero fluid balance. Bolus of no more than 5 ml per kilogram; no other intravenous fluids were to be administered before surgery unless indicated if using a goal-directed device (esophageal Doppler
or pulse wave analyzer). An infusion of a balanced salt crystalloid solution at a dose of 5 ml per kilogram per hour was administered until the end of surgery. Fluids were given postoperatively at a dose of 0.8 ml per kilogram
per hour. The total administration of fluid during the first 24-hour period was expected to be approximately
half that in the liberal fluid group.

TRIAL OUTCOMES

Primary out come- Disability-free survival up to 1 year after surgery.

Secondary outcomes –

Acute kidney injury

30-day mortality

Major septic complications (sepsis, surgical-site infection, anastomotic leak, or pneumonia)

Serum lactate level (at 6 and 24 hours)

Peak C-reactive protein level

Blood transfusion

Duration of stay in the intensive care unit (ICU) and hospital

Unplanned admission to the ICU

Quality of recovery

TRIAL TREATMENT

During surgery, the median rate of fluid infusion was 6.5 ml per kilogram per hour (interquartile range, 5.1 to 8.4) in the restrictive fluid group.

IT was 10.9 ml per kilogram per hour (interquartile range, 8.7 to 13.5) in the liberal fluid group.

On postoperative day 1, the median rate of fluid infusion was 0.9 ml per kilogram per hour (interquartile range, 0.7 to 1.2) in the restrictive fluid group.

It was 1.5 ml per kilogram per hour (interquartile range, 1.2 to 1.7) in the liberal fluid group.

Patients in the liberal fluid group received a perioperative median of 6 liters,  and those in the restrictive fluid group received 3.7 litres.

RESULTS

The mean age was 66 years, 43% underwent colorectal surgery, and 64% underwent cancer surgery. There were no significant differences between the groups at baseline.

At 1 year, the rate of disability free survival (primary outcome)was not significantly higher with the restrictive fluid regimen than with the liberal fluid regimen.

Patients in the restrictive fluid group had a significantly higher risk of acute kidney injury than those in the liberal
fluid group[8.6% in the restrictive fluid group vs 5.0% in the liberal fluid group (P<0.001)].

DISCUSSION

In this trial, even the liberal  group had less than 2.5 kg weight gain in first 24 hour(Current recommendation).  Median fluid in restrictive group was 3.3 L in first 24 hours in comparison to 6 L in the liberal group. Given the amount of fluid given is even restrictive in the LIBERAL group, there is no question the restrictive group had more incidence of acute kidney injury.

BOTTOMLINE

We can safely have a modestly liberal administration of balanced salt solutions in abdominal surgical patients without having substantial fluid retention. Both hypovolemia and oliguria must be recognized and treated with fluids.  Having said that, excessive fluid administration as outlined in current recommendations should be avoided.

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