A Physician With Thigh Pain.

To prevent death, necrotizing soft-tissue infections should be diagnosed quickly and treated with broad-spectrum antibiotics and surgical debridement.

Predicting bacteremia based on nurse-assessed food consumption at the time of blood culture.

BACKGROUND: Bacteremia and its complications are important causes of morbidity and mortality in hospitalized patients. However, the yield of blood cultures is relatively low, with many false-positive results from bacterial contamination. METHODS: We investigated the relationship between patient food consumption and the presence of bacteremia. This was an observational analysis of a cohort of 1179 patients who underwent blood culture analysis between January 2005 and December 2009. Patients with anorexia-inducing conditions, such as gastrointestinal illness and malignant disease treated with chemotherapy, were excluded. Food consumption was rated by nurses as the percentage of food consumed during the meal preceding the blood culture. Groupings were as follows: low consumption (<50%), moderate (>50% to <80%), and high (>80%). RESULTS: Low consumption was observed in 39.8% of patients, moderate in 17.8%, and high in 41.6%. The average body temperature was 38.1 ± 1.1°C. Bacteremia was present in 18.5%, 3.9%, and 1.4% of patients in the low, moderate, and high food consumption groups, respectively. The negative predictive value was 98.3%, suggesting that bacteremia is very unlikely in the setting of good food intake. CONCLUSION: Bacteremia is an unlikely occurrence in hospitalized patients who maintain adequate food consumption at the time of blood culture.

Perspective: Uses and misuses of thresholds in diagnostic decision making.

The concept of thresholds plays a vital role in decisions involving the initiation, continuation, and completion of diagnostic testing. Much research has focused on the development of explicit thresholds, in the form of practice guidelines and decision analyses. However, these tools are used infrequently; most medical decisions are made at the bedside, using implicit thresholds. Study of these thresholds can lead to a deeper understanding of clinical decision making. The authors examine some factors constituting individual clinicians' implicit thresholds. They propose a model for static thresholds using the concept of situational gravity to explain why some thresholds are high, and some low. Next, they consider the hypothetical effects of incorrect placement of thresholds (miscalibration) and changes to thresholds during diagnosis (manipulation). They demonstrate these concepts using common clinical scenarios. Through analysis of miscalibration of thresholds, the authors demonstrate some common maladaptive clinical behaviors, which are nevertheless internally consistent. They then explain how manipulation of thresholds gives rise to common cognitive heuristics including premature closure and anchoring. They also discuss the case where no threshold has been exceeded despite exhaustive collection of data, which commonly leads to application of the availability or representativeness heuristics. Awareness of implicit thresholds allows for a more effective understanding of the processes of medical decision making and, possibly, to the avoidance of detrimental heuristics and their associated medical errors. Research toward accurately defining these thresholds for individual physicians and toward determining their dynamic properties during the diagnostic process may yield valuable insights.