The role of peripheral perfusion index in predicting biphasic reactions in anaphylaxis patients

Anaphylaxis is a rapidly onset, life-threatening hypersensitivity reaction, and in some patients, a biphasic reaction may develop following initial treatment. This study aims to investigate the prognostic value of the peripheral perfusion index (PPI) in predicting biphasic reactions among patients presenting to the emergency department with anaphylaxis.

The study is prospective and single-centered. A total of 104 patients aged 18 years and older, diagnosed with anaphylaxis in the emergency department, were included. PPI values, along with other vital signs, were measured at 0, 10, 20, and 30 min, as well as after symptom resolution. All patients were observed for a minimum of 6 h to monitor for the development of biphasic reactions.

The median PPI value at the 0-min mark was 2.20 (IQR, 1.52-3.67), while the median PPI value after symptom resolution was 4.20 (IQR, 3.10-6.35). A biphasic reaction occurred in 10.6 % of patients. Among patients who developed a biphasic reaction, PPI values at 0, 10, 20, and 30 min were significantly lower compared to those who did not (p < 0.05). In ROC analysis, a PPI cutoff of ≤2.17 for predicting biphasic reactions yielded 57 % sensitivity and 91 % specificity (AUC = 0.75).

PPI may serve as an accessible and cost-effective test in emergency departments for continuous monitoring of patients diagnosed with anaphylaxis, allowing for assessment of treatment response, early detection of biphasic reactions, and risk evaluation.