Intended for healthcare professionals


Intravenous fluids in adults undergoing surgery

BMJ 2009; 338 doi: (Published 24 June 2009) Cite this as: BMJ 2009;338:b2418
  1. Bette Liu, senior research fellow,
  2. Simon Finfer, professor
  1. 1George Institute for International Health, University of Sydney, Sydney, NSW 2000, Australia
  1. sfinfer{at}

    High quality research is needed before guidelines can be reliable and useful

    The publication of British consensus guidelines on intravenous fluid therapy for adult surgical patients is a welcome and overdue recognition of the importance of this treatment.1 This recognition is timely, because emerging evidence indicates that the choice of fluid and resuscitation protocol may materially affect patients’ outcomes.2 3 4

    Clinical practice guidelines that are well conceived, researched, and written help clinicians provide the best evidence based care. They also help policy makers, clinicians, and patients by providing a benchmark for appropriate practice, and researchers and research funding agencies by identifying gaps in evidence where research is needed. To achieve these goals, guidelines must meet certain quality standards—their scope and purpose should be clearly articulated, they should be based on systematic review of all the relevant primary literature, the search strategies used should be provided for critique, and the criteria by which studies are included or excluded and by which the quality of evidence is rated should be described.5 6

    The British consensus guidelines fall short of attaining these goals. The stated aim of the guidelines is “to provide a basis for good practice in adult patients and a resource for appropriate education.” Thus, the scope and purpose of the document is akin to an old fashioned textbook. The guidelines present 28 recommendations that are an eclectic mixture of topics, which seem to reflect the spheres of interest of the six specialist societies that came together to “try to establish consensus for good perioperative fluid prescribing.” The guidelines cover preoperative, intraoperative, and postoperative fluid management; preoperative mechanical bowel preparation; nutrition; and fluid management in acute kidney injury. The addition of these topics adds complexity rather than clarity, and the authors do not explain why some aspects of patient care are emphasised and others are not.

    As the title suggests, the document presents a consensus statement rather than systematic evidence based guidelines; this is problematic because converting evidence into guidelines requires subjective judgments that are probably moulded by conscious and unconscious biases.7 The authors do not state why they opted for a consensus statement rather than systematic evidence based guidelines, but they may have been concerned that insufficient high quality primary evidence was available to make recommendations at all. This concern seems to be real given that studies cited in support of their recommendations often seem inappropriate—for example, the citation of studies conducted in patients undergoing cardiac surgery in support of recommendations for patients undergoing abdominal surgery.

    Rather than shying away from a systematic evidence based approach because high quality evidence is lacking, evidence based guidelines can play a crucial role in articulating current clinical uncertainty and identifying the urgent need for additional primary research. A good example of evidence based guidelines developed using a clear structured framework in a field where high quality evidence is sparse are the Brain Trauma Foundation’s guidelines for the management of severe traumatic brain injury.8 Now in their third edition, they deal with clearly defined and focused clinical questions, grade their recommendations on the basis of the strength of the available evidence, and provide a structured discussion of the literature as well as detailed summaries of the studies on which the guidelines are based. If insufficient primary data are available to make a recommendation this is explicitly stated, as is the need for additional research.

    Methodological concerns aside, do the guidelines achieve their goal of providing “a basis for good practice in adult patients and a resource for appropriate education”? Will they help clinicians, especially junior ones, in managing intravenous fluid therapy in surgical patients, and would adopting them improve outcomes for patients?

    Given the lack of high quality evidence on the effect of fluid therapy on outcomes it is difficult to answer those questions with certainty. The first guideline recommends the use of balanced salt solutions rather than normal saline. Although administration of normal saline can cause hyperchloraemic acidosis, we do not know whether this is harmful to patients9; adopting this recommendation is unlikely to harm patients, but it may not have any tangible benefit. Other recommendations may not be so benign; treatment with fluid and dopexamine to achieve a predetermined value for systemic oxygen delivery is recommended on the basis of small single centre trials and without detailing what the target should be or how it should be achieved. Similar approaches have proved ineffective or even harmful when tested in larger or multicentre trials.10 11

    The danger in providing consensus guidelines endorsed by specialist societies is that clinicians may feel pressured to adopt interventions that may, in the longer term, be found to cost more and to do more harm than good. We agree with the recently expressed view that unless recommendations are based on high quality primary research, then perhaps guidelines should be avoided completely, and clinicians would be better off making clinical decisions on the basis of primary data.7

    Fluid therapy is an important, complex, and poorly researched area of everyday clinical practice that is often delegated to the most junior members of clinical teams. Increasingly the evidence suggests it can affect important outcomes, including mortality. The opportunity still exists for the development of guidelines using a robust systematic evidence based approach, and for them to highlight the urgent need for more high quality primary research.


    Cite this as: BMJ 2009;338:b2418


    • Competing interests: SF and BL are involved in investigator initiated fluid resuscitation research, some of which has been funded by CSL Bioplasma and Fresenius Kabi Deutschland. The funders had no effect on the conduct, analysis, or reporting of the research.

    • Provenance and peer review: Commissioned; not externally peer reviewed.


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