Skin necrosis following local anesthetic: Same presentation for two different diagnoses.

BACKGROUND: Local anesthetics (LA) are widely used in medicine and are generally well tolerated. Although most adverse reactions are nonallergic, LA are a frequent reason for allergy consultation. OBJECTIVE: We want to expand the differential diagnosis of adverse reactions to LA by presenting rare diagnoses. METHODS: We present here two patients with similar clinical presentations, namely skin necrosis after local anesthesia with lidocaine, but with two different final diagnoses. RESULTS: For Patient 1, skin necrosis was imputed to the vasoconstrictor effect of epinephrine in a patient with vascular background aggravated by heavy consumption of tobacco and cannabis. Patient 2 final diagnosis was Nicolau syndrome (embolia cutis medicamentosa), a cutaneous necrosis at the site of injection. CONCLUSIONS: The allergist should be aware of these diagnoses and include them in the differential diagnosis of local anesthetic hypersensitivity.

Adherence to long-term oxygen therapy in patients with chronic obstructive pulmonary disease.

Long-term oxygen therapy (LTOT) has beneficial effects on survival in patients with chronic obstructive pulmonary disease (COPD) and severe hypoxemia at rest. Two landmark trials suggested that these benefits depend on the time of exposure to oxygen. Patients are usually prescribed LTOT for at least 15-18 hours/day. The primary objective of this study was to determine the average daily exposure to supplemental oxygen in patients with severely hypoxemic COPD who were newly prescribed LTOT and the proportion of patients who were adherent to their prescription. The secondary objective was to identify predictors of compliance to LTOT. We performed a retrospective observational study of patients newly registered in a regional home oxygen program in Quebec, Canada, between July 1, 2013, and December 31, 2014. Daily exposure to oxygen was objectively measured from the concentrator's counter clock. From 196 patients registered in the program during the study period, 115 contributed to the analysis. Most patients ( n = 84; 73%) were prescribed oxygen for ≥18 hours/day. Overall, the 115 patients were exposed to home oxygen for 17.8 hours/day; 60% of the patients were compliant according to our definition. Increasing age and ambulatory oxygen utilization predicted adherence to oxygen therapy. Adherence to home oxygen therapy is suboptimal. Behavioral and psychological interventions to improve compliance to LTOT should be investigated.

Safety of Direct Drug Provocation for the Evaluation of Penicillin Allergy in Low-Risk Adults.

BACKGROUND: About 10% of patients have a penicillin allergy label, but less than 5% of them are actually allergic. Unnecessary penicillin avoidance is associated with serious medical consequences. Given the growing number of these labels, it is imperative that our diagnostic strategy for penicillin allergy be as efficient as possible. The validity of traditionally used skin tests (STs) has been questioned, whereas drug provocation testing (DPT), the criterion standard, without previous ST appears very safe in most cases. OBJECTIVE: To evaluate the safety of direct DPT without consideration for ST results and the validity of ST in the diagnosis of penicillin allergy. METHODS: In this prospective cohort study without a control group, we recruited patients consulting an allergist for penicillin allergy. Patients underwent ST followed by DPT regardless of ST results. Patients with anaphylaxis to penicillin within the past 5 years or a severe delayed reaction were excluded, as were those with significant cardiorespiratory comorbidity. RESULTS: None of the 1002 recruited patients had a serious reaction to DPT. Ten (1.0%) had a mild immediate reaction, of whom only 1 (0.1%) was considered likely IgE-mediated. The positive and negative predictive values of ST for an immediate reaction were 3.6% and 99.1%, respectively. CONCLUSIONS: In a low-risk adult population reporting penicillin allergy, ST has very poor positive predictive value. Direct DPT without ST is safe and appears to be an ideal diagnostic strategy to remove penicillin allergy labels that could be implemented in first-line practice.

Global patterns of drug allergy-induced fatalities: a wake-up call to prevent avoidable deaths.

PURPOSE OF REVIEW: To identify patterns and key issues though a systematic review in order to support prevention strategies and reduce avoidable deaths related to drug-induced anaphylaxis (DAF). RECENT FINDINGS: DAF rate has been estimated by 0.13-0.53/106 population/year. General global trends of DAF are increasing over time, mostly occurring at healthcare settings (62%) with a similar gender distribution and an average age of 53 years. Antibiotics, anaesthetics, radio-contrast media and NSAIDs were the most frequently implicated agents. Main comorbidities were personal history of drug allergy, cardiovascular diseases and asthma. Main manifestations were cardiovascular and respiratory commitments. Use of adrenaline is mentioned in only 29% of the articles. SUMMARY: DAF is increasing worldwide and most cases are iatrogenic. This first systematic review of DAF identified key gaps and served as a wake-up call to prevent avoidable deaths. Phenotype at risk for DAF was represented by patients aged more than 54 years, with personal history of drug allergy/hypersensitivity with no or incomplete allergological work-up, cardiovascular disease and/or asthma with need of hospitalization and/or frequent healthcare assistance. Additional risk for those who need frequent use of intravenous antibiotics and/or undergoing surgery or image investigation with radiocontrast media.

Hypersensitivity reactions to iodinated radiocontrast media: Cluster analysis reveals distinct clinical phenotypes.

Background: Drug hypersensitivity reaction (DHR) to iodinated radiocontrast media (iRCM) is reported in 1%-3% of injections. Risk assessment of patients with suspicion of DHR to iRCM relies solely on clinical phenotyping and drug allergy workup. Using a novel unsupervised TwoStep cluster analysis, we aimed to identify prototypic patterns within a large cohort of patients evaluated for a potential iRCM DHR. Methods: A retrospective study was conducted using data from the Drug Allergy and Hypersensitivity Database of the Allergy Unit, University Hospital of Montpellier, Montpellier, France. All referred patients during February 2001 to December 2019 with suspicion of iRCM DHR with either confirmed positive or confirmed negative skin tests were included in the analysis. Results: A total of 1439 patients were evaluated. The chronology of the index reaction was immediate and nonimmediate in 77.1% and 22.4%, respectively. Cluster analysis categorized the total study population in 5 clusters. Cluster 1 compiled all nonimmediate and cluster 2-5 almost all immediate reactors. Cluster 1 and 2 had recent reactions (<1 y) with mostly known iRCMs and the highest iRCM allergy prevalence (16-17%). In the other clusters, more remote reactions, unknown iRCMs and a lower allergy prevalence (3-8%) was observed. Chronology and semiology of the index reaction were the factors most strongly differentiated among clusters. History of anaphylactic shock and chronology of immediate hypersensitivity reactions were shown to be independent predictors of allergy with adjusted OR (aOR) of 4.68 (95%CI: 3.01-7.27, p < 0.001) and 2.51 (95%CI: 1.67-3.78, p < 0.001), respectively. Conclusions: Unsupervised cluster analysis identified 5 prototypic patterns within patients with a suspected DHR to iRCMs. Well-phenotyped patients cluster together in 2 groups in which the prevalence of allergy is approximately 1 in 6. However, this value decreases for patients with reactions dating back to more than a decade.