Mast cell activation during suspected perioperative hypersensitivity: a need for paired samples analysis.

Abstract Background Perioperative hypersensitivity (POH) reactions constitute a significant clinical and diagnostic challenge. A transient increase in serum tryptase during POH reflects mast cell activation (MCA) and helps to recognize an underlying hypersensitivity mechanism. Objective This study aims to determine the diagnostic performance of different tryptase decision thresholds based upon single and paired measurements to document MCA in suspected POH. Methods Acute serum tryptase (aST) and baseline serum tryptase (bST) samples were obtained from patients referred to our outpatients’ clinic because of clinical POH. Tryptase samples from controls were obtained before induction (Tt0) and 1.5 hours after induction (Tt1) in uneventful anesthesia. Different cut-off points for delta tryptase (ΔT) and the percentage increase of tryptase (%T) were calculated and compared to existing thresholds: aST > [1.2 x (bST) + 2] (consensus formula), aST >11.4 ng/mL and aST >14 ng/mL. Results POH patients had higher bST and aST leves compared to controls (respectively 5.15 vs 2.28 ng/mL for bST and 20.30 vs 1.92 ng/mL for aST). The consensus formula and a ΔT of ≥3.2 ng/mL held the highest accuracies to document MCA in POH (resp. 81 and 82%). A bST of > 8 ng/mL was present in 4% of controls, 5% of grade 1 POH, 24% of grade 2 POH, 15% of grade 3 POH and 17% of grade 4 POH. Conclusion Our data endorse the consensus formula for detection of MCA in POH. Furthermore, it shows that a bST of > 8ng/mL was associated with occurrence of anaphylaxis.