A day with Cochrane ACE and an electrolyte balancing act.

Tuesday June 7, Cochrane ACE hosted 41 delegates at the Royal College of Anaethetists in London. As part of the educational program we were invited to critically-appraise the intervention Review;

Burdett E, Dushianthan A, Bennett-Guerrero E, Cro S, Gan TJ, Grocott MPW, James MFM, Mythen MG, O’Malley CMN, Roche AM, Rowan K. Perioperative buffered versus non-buffered fluid administration for surgery in adults. Cochrane Database of Systematic Reviews 2012, Issue 12. Art. No.: CD004089. DOI: 10.1002/14651858.CD004089.pub2.

It has become fashionable for opinion leaders to decry the routine use of the cheapest isotonic salt solution in anaesthesia and critical care; Hamburger solution, or Normal Saline 0.9%. Self-evidently one would have to give an awful lot of it to cause a significant hyperchloraemia. At the time of this review there was no evidence-backed reason to prefer a more expensive bag with less chloride. When I was appointed to Consultancy in 1987 I ensured that plasma chloride was reported on every “U&E” in critical care in Southampton, so we were able to use 0.9% quite safely and saving an awful lot of money along the way. In fact we used the saving to buy the Shackleton department’s first computer in 1988. In the few patients for whom chloride became an issue, isotonic sodium bicarbonate 1.26% could be used instead of chloride 0.9%. There was the added benefit of applying Peter Stewart’s Quantitative Acid-Base approach at the bedside. I had no idea until recently that many (most?) ICUs were still not doing routine chloride monitoring. Lactate monitoring is probably commoner than chloride!

It is interesting to read the Reviewers opinion back in 2012; “(buffered solutions are) a safe alternative to non-buffered fluid administration and are not associated with hyperchloraemic metabolic acidosis. They are therefore appropriate to use as a fluid replacement during surgery and should be considered for any patient who has, or is at risk of, metabolic derangement.”

What about cost? we ask. There were no cost data reported, they reply. But we all know that premium prices are charged for buffered solutions, even though they cost no more to produce, we challenge. Indeed several of you disclose close ties to manufacturing pharmaceutical companies and most of you have a Hospital Pharmacist who could provide cost data.

Since 2012 several observational studies suggesting that 0.9% causes renal failure have been published, but would a journal bother to publish a negative finding on this topic? We needed an RCT and New Zealand delivered one in 2015. (1) For the vast majority of ICU patients who get just 2, 3, or 4 litres of isotonic salt solution during their stay there is no advantage to paying more for reduced chloride bags. Now they plan a bigger and more expensive trial enrolling sicker patients at higher risk of renal failure and death and drowning them in silly volumes of salty water. The perplexed onlooker says why not implement routine chloride monitoring so you can tailor fluid prescriptions rationally to the need of the individual patient before you? Why are you so intent on demonising a bag of salty water? Every brainless prescriber would love to have a Universal IV bag that suited every patient, and you appear to be searching for that magic bullet. There isn’t one. (2) How I wish we could be investing this pointless research time and money to a more 21st-century topic.

REFS

  1. Young P, Bailey M, Beasley R et al. Effect of a Buffered Crystalloid Solution vs Saline on Acute Kidney Injury Among Patients in the Intensive Care Unit: The SPLIT Randomized Clinical Trial. JAMA. 2015;314:1701-1710.
  2. Woodcock T. GIFTAHo; an improvement on GIFTASuP? New NICE guidelines on intravenous fluids. Anaesthesia. 2014;69:410-415.

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