Histamine release and mast cell triggering are related to severe reactions. An IgE-related mechanism is strongly suspected. Radiologists should be trained to identify and treat anaphylactic shock in patients who react to iodinated contrast material.

The incidence of immune-mediated anaphylaxis during anesthesia ranges from 1 in 10,000 to 1 in 20,000. Neuromuscular blocking agents represent the most frequently involved substances, followed by latex and antibiotics, but every drug or substance used may be involved. Diagnosis relies on tryptase measurements at the time of the reaction and skin tests and specific IgE or basophil activation assays.

Neuromuscular blocking agents are the leading drugs responsible for immediate hypersensitivity reactions during anaesthesia. Most hypersensitivity reactions represent IgE-mediated allergic reactions. Their incidence is estimated to be between 1 in 3,000 to 1 in 110,000 general anaesthetics. However striking variations have been reported among countries. The mechanism of sensitisation seems to implicate the presence of a substituted ammonium ion in the molecule. Due to lack of exposure prior to the reaction in a large number of reactors, it has been hypothesised that sensitisation may involve other, as yet undefined, substituted (quaternary and tertiary) ammonium ion containing compounds such as pholcodine, present in the environment of the patient. This hypothesis is still under investigation. The mechanism of non-IgE mediated hypersensitivity reactions is less well known. Identified mechanisms correspond to direct histamine release or interactions with muscarinic and nicotinic receptors. Allergic reactions cannot be clinically distinguished from non-IgE-mediated reactions. Therefore, any suspected hypersensitivity reaction must be investigated using combined pre and postoperative testing. Because of the frequent but not systematic cross-reactivity observed with muscle relaxants, every available neuromuscular blocking agent should be tested, using intradermal tests to confirm the responsibility of the suspected drug which should be definitely excluded. Cross-sensitivity investigation will also try to identify the safety of drugs that can be potentially used in future anaesthesia. The determination of basophil activation investigations using direct leukocyte histamine release test or flow cytometry would be of particular interest to investigate cross sensitisation in complement to skin tests. There is no demonstrated evidence supporting systematic pre-operative screening in the general population at this time. However, since no specific treatment has been shown to reliably prevent anaphylaxis, allergy assessment must be performed in all high-risk patients. In view of the relative complexity of allergy investigation, and of the differences between countries, an active policy to identify patients at risk and to provide any necessary support from expert advice to anaesthetists and allergologists through the constitution of allergo-anaesthesia centres in every country should be promoted.

Previous studies have suggested that procalcitonin is a reliable marker for predicting bacteremia. However, these studies have had relatively small sample sizes or focused on a single clinical entity. The primary endpoint of this study was to investigate the diagnostic accuracy of procalcitonin for predicting or excluding clinically relevant pathogen categories in patients with suspected bloodstream infections. The secondary endpoint was to look for organisms significantly associated with internationally validated procalcitonin intervals. We performed a cross-sectional study that included 35,343 consecutive patients who underwent concomitant procalcitonin assays and blood cultures for suspected bloodstream infections. Biochemical and microbiological data were systematically collected in an electronic database and extracted for purposes of this study. Depending on blood culture results, patients were classified into 1 of the 5 following groups: negative blood culture, Gram-positive bacteremia, Gram-negative bacteremia, fungi, and potential contaminants found in blood cultures (PCBCs). The highest procalcitonin concentration was observed in patients with blood cultures growing Gram-negative bacteria (median 2.2 ng/mL [IQR 0.6–12.2]), and the lowest procalcitonin concentration was observed in patients with negative blood cultures (median 0.3 ng/mL [IQR 0.1–1.1]). With optimal thresholds ranging from ≤0.4 to ≤0.75 ng/mL, procalcitonin had a high diagnostic accuracy for excluding all pathogen categories with the following negative predictive values: Gram-negative bacteria (98.9%) (including enterobacteria [99.2%], nonfermenting Gram-negative bacilli [99.7%], and anaerobic bacteria [99.9%]), Gram-positive bacteria (98.4%), and fungi (99.6%). A procalcitonin concentration ≥10 ng/mL was associated with a high risk of Gram-negative (odds ratio 5.98; 95% CI, 5.20–6.88) or Gram-positive (odds ratio 3.64; 95% CI, 3.11–4.26) bacteremia but dramatically reduced the risk of PCBCs or fungemia. In this large real-life setting experience with more than 35,000 patients, procalcitonin was highly effective at excluding bloodstream infections regardless of pathogen categories. The results from our study are limited by its cross-sectional design and deserve to be validated in prospective longitudinal studies.