CMAJ Readers' Forum

Clinical opinion histograms for transfusion decisions

Online posting: Oct. 16, 1997
Published in print: November 15, 1997 (CMAJ 1997;157:1350)
Transfusion decision-making has become much more complex than it used to be, and the process is now frequently aided by published algorithms or consensus statements.1-5 Unfortunately, these sources do not always provide specific suggestions for specific clinical situations. We used the Internet to sample the opinions of a number of practising physicians about the transfusion trigger they would pick in a set of hypothetical clinical settings and then constructed a series of histograms of minimum acceptable hemoglobin concentrations for a variety of clinical scenarios. For example, for a sample of 26 practising anesthesiologists asked to provide a perioperative transfusion trigger for an otherwise healthy anemic 45-year-old woman undergoing total abdominal hysterectomy for menorrhagia, the mean transfusion trigger was 76.3 g/dL (standard deviation 7.7). Opinion data were also obtained for perioperative scenarios involving patients with coronary artery disease, patients with prior successful myocardial vascularization, elderly patients and others.

With this method, clinicians dealing with an actual clinical situation found to match one of the hypothetical scenarios might choose a transfusion trigger that is the mean of the opinion histogram corresponding to that scenario, thus choosing a middle- of-the-road decision point. Alternatively, physicians with patients who have specifically requested not to receive transfusions unless the opinion that the transfusion is needed is shared by a substantial majority of physicians might pick a transfusion decision threshold 2 standard deviations below the mean.

It is our hope that with the continuing development of histogram data for a large number of representative clinical scenarios this technique of expressing clinical opinion may become useful in clinical decision-making.

D. John Doyle, MD, PhD
Kevin Chan, BASc
Department of Anaesthesia
Toronto Hospital and University of Toronto
Toronto, Ont.
djdoyle@inforamp.net
http://doyle.ibme.utoronto.ca

References

  1. Practice guidelines for blood component therapy: a report by the American Society of Anesthesiologists Task Force on Blood Component Therapy. Anesthesiology 1996;84:732-47.
  2. Spence RK, editor. Consensus conference: blood management. Surgical practice guidelines. Am J Surg 1995:170(6A[suppl]):1S-73S.
  3. Van Woerkens ECSM, Trouwborst A, van Lanschot JBB. Profound hemodilution: What is the critical level of hemodilution at which oxygen delivery-dependent oxygen consumption starts in an anesthetized human? Anesth Analg 1992;75:818-21.
  4. Robertie PG, Gravlee GP. Safe limits of isovolemic hemodilution and recommendations for erythrocyte transfusion. Int Anesthesiol Clin 1990;28:197-204.
  5. Perioperative red blood cell transfusion [consensus conference]. JAMA 1988;260:2700-3.
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