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Normal saline not the best surgical replacement fluid: study

Reuters Health • The Doctor's Channel Daily Newscast

NEW YORK (Reuters Health) – In looking back at more than 30,000 patients who had major open abdominal surgery over a five-year period, researchers found that those who received calcium-free physiologically balanced crystalloid solution for fluid replacement suffered fewer major complications than those who received normal saline.

“Patients who received 0.9% saline experienced more complications, including infections, blood transfusions and (need for) dialysis, than patients who received a fluid with a salt composition more like natural plasma,” Dr. Andrew D. Shaw, of the Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina, told Reuters Health.

“Emergency surgery patients who were treated with 0.9% saline also died more frequently even when other risk factors were accounted for,” he said.

Normal saline is “extremely widely used in hospital practice in the United States. However, there are preclinical – and now clinical data – that suggest it may not be the best fluid to use for patients in the hospital. Alternatives to 0.9% saline are available, and are no more expensive,” Dr. Shaw added.

Normal saline when used as the primary resuscitative fluid in surgery results in a “predictable hyperchloremic metabolic acidosis,” he and his colleagues note in a report online March 30 in Annals of Surgery. It may also lead to adverse effects including immune dysfunction, GI dysfunction, and decreased renal blood flow.

Using the Premier Perspective Comparative Database, a large U.S. automated hospital claims database, they assessed outcomes of adults who had major open abdominal surgery between 2005-2009 and received either 0.9% saline (n=30,994) or a balanced solution (Plasma-Lyte A or Plasma-Lyte 148, Baxter Healthcare) on the day of surgery (n=926).

The electrolyte content of Plasma-Lyte A and Plasma-Lyte 148 is identical: sodium 140 mEq/L, potassium 5mEq/L, magnesium 3 mEq/L, chloride 98 mEq/L, acetate 27 mEq/L, and gluconate 23 mEq/L. The solutions only differ in pH, where Plasma-Lyte A has a pH of 7.4 and Plasma-Lyte 148 has a pH of 5.5.

For the entire cohort, the in-hospital death rate was higher in the saline group than the balanced group (5.6% vs 2.9%; p<0.001). One or more major complications occurred in 33.7% of the saline group versus 23% of the balanced group (p<0.001). Patients who received saline had more postoperative infections (p=0.006), renal failure requiring dialysis (p<0.001), blood transfusions (p<0.001) and electrolyte disturbances (p=0.046). In a 3:1 propensity-matched sample (926 balanced solution, 2778 saline), receipt of the balanced solution was associated with fewer complications (odds ratio 0.79). Furthermore, physicians caring for patients who got saline ordered more tests (arterial blood gases and lactate levels) and more treatments (buffers, blood products, and dialysis) “presumably to investigate and manage observed acid-base abnormalities and their consequences in these patients,” the investigators report. “Whether the increased risk is due to hyperchloremic acidosis alone or to other effects of saline administration is unclear but it does not appear to be due to chance or to patient or hospital characteristics,” they add. Dr. Shaw told Reuters Health: “Since there are no data suggesting that 0.9% saline is any better than the alternatives, there are no cost savings, and there may be harm, perhaps it is time to limit the use of 0.9% saline in hospital practice to those special circumstances where it may be beneficial, such as traumatic brain injury and severe gastric fluid losses.” “We plan to extend our research to include patients of all types in the hospital, not just those undergoing surgery,” he added. The study was funded by Baxter Healthcare. One author on the study is an employee of Baxter Healthcare. SOURCE: Ann Surg 2012.