Hypersensitivity to contrast media and dyes

Delayed hypersensitivity reactions to iodinated contrast media: A diagnostic approach by skin tests

BACKGROUND

Adverse drug reactions to iodinated contrast media (ICM) have risen due to their increasing use in x-ray-based imaging modalities. Delayed hypersensitivity reactions are mainly caused by nonionic monomeric compounds and represent an issue impacting the diagnostic-therapeutic pathways of cancer, cardiology and surgery patients.

OBJECTIVES

To prospectively evaluate the usefulness of skin tests in delayed hypersensitivity reactions to ICM and to evaluate the tolerability of iobitridol, a monomeric nonionic low osmolality compound, as a possible safe alternative.

METHODS

Patients with delayed hypersensitivity reactions to ICM referred to us from 2020 to 2022 were prospectively enrolled in the study. All patients underwent patch test and, if negative, intradermal test with the culprit ICM and iobitridol as alternative.

RESULTS

A total of 37 patients (females 24, 64.9%) were enrolled in the study. Iodixanol and iomeprol were the most frequently involved ICM (48.5% and 35.2%, respectively); 62.2% of patients presented maculopapular eruption, while 37.8% reported delayed urticaria-like rash. Skin tests resulted positive to the culprit ICM in 19 patients (51.4%), 16 to patch test and 3 to intradermal test. Skin tests with iobitridol, tested as alternative, resulted positive in 3/19 patients (15.8%). All 16 patients with negative results to iobitridol were administered this ICM and tolerated it.

CONCLUSIONS

In at least half of patients, delayed-type hypersensitivity was demonstrated by skin tests, particularly by patch test. This diagnostic approach resulted simple, cost-effective and safe, not only to confirm the culprit ICM but also to identify iobitridol as feasible alternative.

Hypersensitivity to gadolinium-based contrast

PURPOSE OF REVIEW

The use of contrast media is increasing in recent decades. Although gadolinium-based contrast agents (GBCAs) are generally well tolerated, adverse reactions, including hypersensitivity reactions (HSRs), although infrequent, may occur. It is important to perform a thorough allergological evaluation in patients with suspected GBCA-HSRs to avoid potentially serious reactions in subsequent exposures.

RECENT FINDINGS

Data on GBCA-HSRs are scarce. Most published articles dealing with skin tests and drug provocation tests (DPTs) with GBCAs are case series and small cohorts. Controversies exist about the role of premedication for preventing HSRs on subsequent exposures. Selection of well tolerated alternatives is based on potential cross-reactivity among GBCAs; however, the extent of cross-reactivity among them remains unclear.

SUMMARY

As premedication is not useful because breakthrough reactions are frequent in patients with GBCA-HSRs in subsequent exposures, an allergological evaluation is required. Available data suggest a high negative predictive value of skin tests, being crucial for guiding the selection of an alternative GBCA. However, DPTs are still necessary to confirm or exclude the diagnosis or find alternative GBCAs. Cross-reactivity is high among GBCAs belonging from the same group, mainly among macrocyclic compounds, so this must be taken into account for selecting alternatives.

Revisiting the Definition of Anaphylaxis

PURPOSE OF REVIEW

Anaphylaxis is a common phenomenon that has been studied for many decades. Despite this, there is still disagreement among organizations regarding the precise definition for anaphylaxis. This article discusses the difference between the proposed definitions of anaphylaxis. Furthermore, the most up-to-date literature on specific subtypes of anaphylaxis is reviewed, and implications for clinical practice are discussed.

RECENT FINDINGS

Recent literature on various subtypes of anaphylaxis has been conducted. This has helped clarify guidelines for conditions such as allergy to radiocontrast media, idiopathic anaphylaxis, and food-dependent exercise-induced anaphylaxis. Recent literature has also studied available biomarkers for anaphylaxis and the cost-effectiveness of current standard-of-care prescription of epinephrine autoinjectors. Anaphylaxis is an increasingly more frequent phenomenon and remains a hot topic in current research. Much progress has been made in clarifying the definition of anaphylaxis and differentiating between subtypes, but more research is needed to identify a readily available biomarker for anaphylaxis and identify the standard of care for various subtypes of anaphylaxis.

Incidence and severity of nonionic low-osmolar iodinated contrast medium-related adverse drug reactions in the Republic of Korea: Comparison by generic

We aimed to report the incidence and severity of nonionic low-osmolar iodine contrast medium (ICM)-related adverse drug reactions (ADRs) in the Republic of Korea, by analyzing data from our single tertiary institution and published Korean reports, and to determine whether there is a difference in the incidence of ICM-related ADR by ICM generics. A total of 1,161,419 consecutive contrast-enhanced computed tomography (CT) examinations between January 2016 and December 2021 at Asan Medical Center were included. A systematic search of the literature investigating the incidence of ICM-related ADR in the Republic of Korea published up to December 31, 2021 was performed. We pooled these outcomes with those of our study using a binomial-normal model, and the pooled incidences of ADRs were compared among ICM generics using chi-square tests. Seven studies with a total of 2,570,986 contrast-enhanced CT examinations from 12 institutions were included. The pooled incidences of overall, mild, moderate, and severe ICM-related ADRs in the Republic of Korea were 0.82% (95% CI: 0.61%-1.10%), 0.72% (95% CI: 0.50%-1.04%), 0.11% (95% CI: 0.08%-0.15%), and 0.013% (95% CI: 0.010%-0.018%), respectively. In multiple pairwise comparisons, there were no significant differences in the overall incidence of ADRs between ICM generics, except iomeprol versus iobitridol and iomeprol versus iohexol. For moderate and severe ADRs, there were no significant differences in ADR incidence between ICM generics. The incidence of moderate and severe ICM-related ADRs did not differ among ICM generics. Our results suggest that no restriction is required for selection among nonionic low-osmolar ICMs.

Allergic and other adverse reactions to drugs used in anesthesia and surgery

The list of drugs patients may be exposed to during the perioperative and postoperative periods is potentially extensive. It includes induction agents, neuromuscular blocking drugs (NMBDs), opioids, antibiotics, sugammadex, colloids, local anesthetics, polypeptides, antifibrinolytic agents, heparin and related anticoagulants, blue dyes, chlorhexidine, and a range of other agents depending on several factors related to individual patients’ clinical condition and progress in the postoperative recovery period. To avoid poor or ultrarapid metabolizers to a particular drug (for example tramadol and codeine) or possible adverse drug reactions (ADRs), some drugs may need to be avoided during or after surgery. This will be the case for patients with a history of anaphylaxis or other adverse events/intolerances to a known drug. Other drugs may be ceased for a period before surgery, e.g., anticoagulants that increase the chance of bleeding; diuretics for patients with acute renal failure; antihypertensives relative to kidney injury after major vascular surgery; and serotonergic drugs that together with some opioids may rarely induce serotonin toxicity. Studies of germline variations shown by genotyping and phenotyping to identify a predisposition of genetic factors to ADRs offer an increasingly important approach to individualize drug therapy. Studies of associations of human leukocyte antigen (HLA) genes with some serious delayed immune-mediated reactions are ongoing and variations of drug-metabolizing cytochrome CYP450 enzymes, P-glycoprotein, and catechol-O -methyltransferase show promise for the assessment of ADRs and non-responses to drugs, particularly opioids and other analgesics. Surveys of ADRs from an increasing number of institutions often cover small numbers of patients, are retrospective in nature, fail to clearly identify culprit drugs, and do not adequately distinguish immune-mediated from non-immune-mediated anaphylactoid reactions. From the many surveys undertaken, the large list of agents identified during and after anesthesia and surgery are examined for their ADR involvement. Drugs are classified into those most often involved, (NMBD and antibiotics); drugs that are becoming more frequently implicated, namely antibiotics (particularly teicoplanin), and blue dyes; those becoming less frequently involved; and drugs more rarely involved in perioperative, and postoperative adverse reactions but still important and necessary to keep in mind for the occasional potential sensitive patient. Clinicians should be aware of the similarities between drug-induced true allergic type I IgE/FcεRI- and pseudoallergic MRGPRX2-mediated ADRs, the clinical features of each, and their distinguishing characteristics. Procedures for identifying MRGPRX2 agonists and diagnosing and distinguishing pseudoallergic from allergic reaction mechanisms are discussed.

Preclosure povidone-iodine lavage in total hip replacement surgery: Infection outcomes and cost-benefit analysis

OBJECTIVE

To report the outcomes and cost-benefit analysis of preclosure povidone-iodine lavage (PrePIL) used to reduce the risk of infection following total hip replacement (THR) surgery.

STUDY DESIGN

Retrospective study.

ANIMALS

One thousand six hundred ninety-nine dogs, 17 cats.

METHODS

The medical records of 2213 consecutive THR cases were reviewed to determine the incidence of infection. The last 102 were treated with PrePIL using a commercially sourced 0.035% povidone-iodine solution. Postoperative infection rates were compared. A cost-benefit analysis was used to calculate if a PrePIL protocol is economically feasible.

RESULTS

Twenty-one THRs out of 2111 (0.99%) that did not have PrePIL developed infection. Infection occurred in none of the 102 PrePIL cases. Cost analysis revealed a PrePIL break-even cost at $49.74 and a break-even infection rate of 0.949%. No complications were identified related to the use of PrePIL.

CONCLUSION

Preclosure povidone-iodine lavage appeared to be efficacious in lowering THR infection rates, and it appeared to be safe for this use based on our 102 consecutive cases. The cost of the PrePIL was minimal compared to the overall cost to resolve THR infection and the potential effect on hip function prognosis. The math formulas developed can be used by surgeons to calculate cost effectiveness and break-even cost based on their THR infection rate, and to compare to the cost of a THR revision and infection resolution.

CLINICAL SIGNIFICANCE

At current costs, PrePIL can be used in 2415 THR cases at a similar cost of a single revision surgery and resolution of a periprosthetic infection.

In Vivo Oral Sentinel Lymph Node Mapping by Near-Infrared Fluorescent Methylene Blue in Rats

This study aimed to demonstrate the feasibility of near-infrared (NIR) fluorescence imaging using methylene blue (MB) for detecting oral sentinel lymph nodes (SLNs) in rats and compared MB’s tracer effects with those of indocyanine green (ICG) in SLN mapping. Different concentrations of MB were injected into the rats’ left lingual submucosa to determine the optimal concentration by using a continuous (1 h) MI-1 fluorescence imaging system. To compare the tracer effects of the optimal MB concentration with ICG in oral SLN mapping, MI-1 imaging was continuously monitored for 12 h. The mean signal-to-background ratio (SBR) of the SLNs and SLN fluorescence area fraction were analyzed. SLNs and lymphatic vessels were clearly visible in all rats. The optimal injection dose of MB infected into lingual submucosa for NIR fluorescence imaging was 0.2 mL of 6.68 mM MB. During continuous monitoring for 12 h, the mean SBR of the SLNs was significantly higher in the ICG groups than in the MB groups (p < 0.001). However, the area fraction of SLN fluorescence in the ICG groups increased continuously, owing to strong fluorescent contamination. This study examined the feasibility of detection of draining lymph nodes in the oral cavity of rats using MB NIR fluorescence imaging. MB causes less fluorescent contamination than does ICG, which shows promise for clinical research and application.

Risk factors of anaphylaxis in Korea: Identifying drug-induced anaphylaxis culprits using big data

Drug-induced anaphylaxis is a fatal medical condition whose incidence has been increasing continuously. Due to differences between genetic backgrounds and health care systems, different populations may be prone to various causative drugs. Using the Health Insurance Service and Assessment Service database, we investigated culprit drugs for drug-induced anaphylaxis and common medication risk factors in the Korean general population. We collected medical prescription histories within 3 days prior to anaphylaxis between January 2011 and December 2019 from the HIRA database. Designed as a case-crossover study, the attributable visits (case visits) were matched to medical visits (control visits) with the drug sets for each visit. We collected a list of medication risk factors for anaphylaxis and calculated the risk ratio of each agent using the chi-square test and conditional logistic regression analysis. A total of 159,473 individuals were listed in the database with a diagnosis of anaphylaxis in the HIRA from 2011 to 2019. After evaluating the suitability of control visits for matching with a case visit, 8168 subjects and 767 drugs were analyzed. The chi-square analysis identified 31 drugs as potential risk factors for drug-induced anaphylaxis in Korea. After applying a conditional logistic regression analysis for each agent, 5 drugs were found to be the common medication risk factors for drug-induced anaphylaxis: cefaclor, iopromide, iohexol, iomeprol, and tolperisone. We found 5 medication risk factors that showed the highest risk of drug-induced anaphylaxis and their degree of risk using an objective methodology in the Korean general population.

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.

A novel activated-zinc antiseptic solution effective against MRSA and Pseudomonas aeruginosa: a pig model

OBJECTIVE

The purpose of this study was to investigate the antimicrobial efficacy of a novel activated zinc solution against meticillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas aeruginosa after one hour, and to evaluate any untoward effect of the solution on local wound tissue at 24 hours after solution exposure in a pig wound model.

METHOD

A pathogen-free, commercially raised, Yorkshire-cross female pig was acquired 12 days prior to the procedure. Within one week prior to the procedure, a small loopful of test bacteria, Pseudomonas aeruginosa (pig-isolate) and MRSA (ATCC-6538), were streaked and cultured on a non-selective agar. Full-thickness wounds (n=24) were created and evenly divided into three groups: control wounds (exposed to bacteria but untreated, n=8); wounds treated with Compound 1 (n=8), and wounds treated with Compound 2 (n=8). All wounds were dressed and monitored for one hour and 24 hours.

RESULTS

After one hour, the wounds treated with Compound 1 and Compound 2 had a mean recoverable total bacteria of 2.8 log colony forming units (CFUs) and 3.5 logCFUs, respectively. After one hour, the wounds treated with Compound 1 and Compound 2 had a mean recoverable MRSA of 2.3 logCFUs and 1.6 logCFUs, respectively (p=0.009). After one hour, the wounds treated with Compound 1 and Compound 2 had a mean recoverable Pseudomonas aeruginosa of 0.3 logCFUs and 0.0 logCFUs, respectively (p=0.000). After 24 hours of exposure to Compound 1 and Compound 2, there was no statistically significant increased necrosis (p=0.12, p=0.31, respectively) or neutrophilic infiltrate (Compound 2, p=0.12) when compared with control wounds.

CONCLUSION

The novel activated-zinc compound used in this study demonstrated a 99.5-99.9% reduction in total bacteria, a 99.9-99.98% reduction in MRSA, and 100% eradication of Pseudomonas aeruginosa one hour after exposure. This novel solution may provide another significant tool to treat and/or prevent wound infections.

Contrast Medium Hypersensitivity: A Large Italian Study with Long-Term Follow-Up

Hypersensitivity reactions (HRs) to contrast media (CM) are a major problem. We compared differences of HRs to iodinated contrast media (ICM) versus gadolinium-based contrast media (GBCM), collecting data on prevalence, type, latency and severity. Secondly, the predisposition to perform new contrast tests, use of premedication and possible appearance of new reactions were explored in a long-term follow-up of 5 years. Clinical data, comorbidities, skin test (ST) results, re-exposure to CM procedures with any new reactions, premedication and CM used were collected. In a retrospective single-center study, 350 patients with mild to moderate HRs were enrolled. Asthma, food allergy, non-allergic drug hypersensitivity and neurologic disease were significantly more frequent in patients with HRs to GBCM compared to the high evidence of cardiovascular disease and history of cancer in patients with HRs to ICM. A marked delay in performing STs was reported by patients with negative results (66 months, p < 0.01). Iomeprol, iopamidol and gadobenic acid were the culprit CM most involved in HRs in patients with positive STs. During follow-up, 7.1% of responders reported new HRs to CM despite negative STs, premedication and infusion of alternative CM in most cases.

What Is the Optimal Irrigation Solution in the Management of Periprosthetic Hip and Knee Joint Infections?

BACKGROUND

Thorough irrigation and debridement using an irrigation solution is a well-established treatment for both acute and chronic periprosthetic joint infections (PJIs). In the absence of concrete data, identifying the optimal irrigation agent and protocol remains challenging.

METHODS

A thorough review of the current literature on the various forms of irrigations and their additives was performed to evaluate the efficacy and limitations of each solution as pertaining to pathogen eradication in the treatment of PJI. As there is an overall paucity of high-quality literature comparing irrigation additives to each other and to any control, no meta-analyses could be performed. The literature was therefore summarized in this review article to give readers concise information on current irrigation options and their known risks and benefits.

RESULTS

Antiseptic solutions include povidone-iodine, chlorhexidine gluconate, acetic acid, hydrogen peroxide, sodium hypochlorite, hypochlorous acid, and preformulated commercially available combination solutions. The current literature suggests that intraoperative use of antiseptic irrigants may play a role in treating PJI, but definitive clinical studies comparing antiseptic to no antiseptic irrigation are lacking. Furthermore, no clinical head-to-head comparisons of different antiseptic irrigants have identified an optimal irrigation solution.

CONCLUSION

Further high-quality studies on the optimal irrigation additive and protocol for the management of PJI are warranted to guide future evidence-based decisions.

Diagnosing and Managing Patients with Reactions to Radiocontrast Media

Purpose of the review

Iodinated radio contrast media (RCM) belong to the most common elicitors of drug hypersensitivity reactions (HR). Urticaria or anaphylaxis may occur ≤ 1(−6) hour(s) (immediate HR) and exanthems (non-immediate HR) develop > 6 h after application of RCM. Evidence for an immunologic mechanism of RCM HR against the different RCM benzene ring molecules and the benefit of allergological testing in patients with previous hypersensitivity reactions is progressively increasing.

Recent findings

Positive skin tests can confirm allergy in patients with previous reactions to RCM and help to select alternative better tolerated RCMs. Severe hypersensitivity reactions are mainly caused by an allergic mechanism, whereas the majority of non-severe reactions appear to be non-allergic. Skin testing is highly recommended to help identify allergic hypersensitivity reactions and to select alternatives. Using structurally different RCM is more effective than premedication for the prevention of future reactions. Drug provocation tests to RCM have been increasingly used, but are not yet standardized among different centers.

Summary

In patients with previous severe hypersensitivity reactions to RCM, skin testing is recommended. For future RCM-enhanced examinations in patients with previous reactions, structurally different, skin test-negative preparations should be applied. Drug provocation tests do confirm or exclude RCM hypersensitivity or may demonstrate tolerability of alternative RCMs.

Delayed anaphylaxis due to gadolinium- A rare clinical scenario

Acute respiratory distress syndrome is a sudden in onset, diffuse inflammatory form of lung injury which may be associated with a variety of etiologies such as pneumonia, sepsis, aspiration, and severe trauma. Prompt recognition and treatment of acute respiratory distress syndrome is critical to reduce the associated high mortality. Severe lung injury presenting as acute respiratory distress syndrome secondary to gadolinium contrast media (gadobutrol) is rarely reported. We describe an interesting case of a 47-year-old woman who presented to the emergency department with acute respiratory failure after gadolinium administration. She was diagnosed with acute respiratory distress syndrome, was admitted to the intensive care unit due to requiring mechanical ventilation. Her condition improved with epinephrine and steroids and she was successfully extubated and discharged from the hospital in one week.

Pharmacological prevention of delayed hypersensitivity reactions caused by iodinated contrast media

Background

Delayed hypersensitivity reactions (DHRs) to radiocontrast media (RCM) occur in approximately 0.5–23.0% of patients and are thought to be caused by T cell-mediated mechanisms. However, an optimal pharmacological preventive strategy is not yet established in patients with histories of delayed reactions to RCM.

Objective

We aimed to evaluate the efficacy of pharmacological prevention in patients with histories of delayed reactions to non-ionic low-osmolar RCM when re-exposed to RCM.

Methods

A retrospective review of electronic medical records of 117 patients with previous histories of DHRs to RCM who visited an allergy clinic for the prevention of reactions after the re-exposure to RCM was conducted. The effects of pharmacological prevention were compared according to the symptom scores of previous reactions based on their intensities and durations with electronic medical records (EMRs).

Results

Of the 117 patients who experienced DHRs after RCM injection, we confirmed the outcomes of RCM re-exposure in 101 patients. For pharmacological prevention, 92 patients (91.1%) received steroids before RCM injection and among them, 50 patients (49.5%) received additional steroids after RCM injection. With this pharmacological prevention, patients of symptoms improved or no recurrence, recurrence of similar previous symptoms, and recurrence of worse symptoms were 98 (97.0%), 2 (2.0%), and 1 (1.0%), respectively. The proportions of no recurrence after pharmacological prevention were lower in patients with severe reactions and higher symptom scores.

Conclusion

Pharmacological prevention showed a beneficial effect in most patients with delayed hypersensitivity to RCM. Further investigations are needed to establish an effective protocol for the prevention of delayed reactions to RCM.

Sentinel lymph node biopsy in patients with endometrial cancer and an indocyanine green or iodinated contrast reaction - A proposed management algorithm

OBJECTIVE

To describe the incidence of adverse reactions to indocyanine green (ICG) administered during sentinel lymph node (SLN) biopsy for endometrial cancer, and to propose an ICG management algorithm for these patients.

METHODS

All patients who underwent surgery for endometrial cancer with SLN biopsy using ICG from 1/2017 to 8/2020 were identified using a single-institution prospective database. Surgical adverse events (SAEs) related to the procedure were identified. A review of the literature was performed.

RESULTS

In all, 1414 patients met inclusion criteria and were evaluated. Sixty-seven (4.7%) patients had a history of either an iodine or contrast allergy. No patients had a history of documented ICG allergy. Among patients with an iodine or contrast allergy, 65 (97%) received a corticosteroid with or without diphenhydramine prior to ICG administration. One hundred five patients (7.4%) experienced 116 SAEs. Among these patients, 3 experienced potentially allergic SAEs possibly related to ICG administration. After thorough chart review, however, the likelihood these SAEs were due to ICG appeared low. No patients experienced an anaphylactic response after ICG admission.

CONCLUSION

There were no anaphylactic reactions to ICG intracervical administration during 1414 consecutive SLN biopsies, including in patients with a documented iodine or contrast allergy. Intracervical injection of ICG is safe, and premedication using corticosteroids with or without diphenhydramine prior to SLN biopsy is a reasonable strategy in patients with iodinated contrast allergy.

Use and Interpretation of Acute and Baseline Tryptase in Perioperative Hypersensitivity and Anaphylaxis

Paired acute and baseline serum or plasma tryptase sampling and determination have recently been included as a mechanistic approach in the diagnostic and management guidelines of perioperative immediate hypersensitivity and anaphylaxis. The timing of this paired sampling is clearly defined in international consensus statements, with the optimal window for acute tryptase sampling between 30 minutes and 2 hours after the initiation of symptoms, whereas baseline tryptase should be measured in a sample collected before the event (preop) or at least 24 hours after all signs and symptoms have resolved. A transient elevation of the acute tryptase level greater than [2 + (1.2 × baseline tryptase level)] supports the involvement and activation of mast cells. Here, we provide the clinical, pathophysiological, and technical rationale for the procedure and interpretation of paired acute and baseline tryptase. Clinical examples, up-to-date knowledge of hereditary α-tryptasemia as a frequent cause of baseline tryptase of 7 μg/L and higher, mastocytosis, other clonal myeloid disorders, cardiovascular or renal failure, and technical improvements resulting in continued lowering of the 95th percentile value are discussed. Clues for improved management of perioperative immediate hypersensitivity and anaphylaxis include (1) sustained dissemination and implementation of updated guidelines; (2) preoperative sample storage for deferred analysis; (3) referral for thorough allergy investigation, screening for mast cell-related disorders, and recommendations for future anesthetic procedures; and (4) sustained collaboration between anesthesiologists, immunologists, and allergists.

A novel deep learning conditional generative adversarial network for producing angiography images from retinal fundus photographs

Fluorescein angiography (FA) is a procedure used to image the vascular structure of the retina and requires the insertion of an exogenous dye with potential adverse side effects. Currently, there is only one alternative non-invasive system based on Optical coherence tomography (OCT) technology, called OCT angiography (OCTA), capable of visualizing retina vasculature. However, due to its cost and limited view, OCTA technology is not widely used. Retinal fundus photography is a safe imaging technique used for capturing the overall structure of the retina. In order to visualize retinal vasculature without the need for FA and in a cost-effective, non-invasive, and accurate manner, we propose a deep learning conditional generative adversarial network (GAN) capable of producing FA images from fundus photographs. The proposed GAN produces anatomically accurate angiograms, with similar fidelity to FA images, and significantly outperforms two other state-of-the-art generative algorithms ([Formula: see text] and [Formula: see text]). Furthermore, evaluations by experts shows that our proposed model produces such high quality FA images that are indistinguishable from real angiograms. Our model as the first application of artificial intelligence and deep learning to medical image translation, by employing a theoretical framework capable of establishing a shared feature-space between two domains (i.e. funduscopy and fluorescein angiography) provides an unrivaled way for the translation of images from one domain to the other.

SIRM-SIAAIC consensus, an Italian document on management of patients at risk of hypersensitivity reactions to contrast media

Hypersensitivity reactions (HRs) to contrast media (CM) can be distinguished in immune-mediated (including allergic reactions) and non-immune-mediated reactions, even if clinical manifestations could be similar. Such manifestations range from mild skin eruptions to severe anaphylaxis, making it important for radiologists to know how to identify and manage them. A panel of experts from the Società Italiana di Radiologia Medica e Interventistica (SIRM) and the Società Italiana di Allergologia, Asma e Immunologia Clinica (SIAAIC) provided a consensus document on the management of patients who must undergo radiological investigations with CM. Consensus topics included: the risk stratification of patients, the identification of the culprit CM and of a safe alternative by an allergy workup, as well as the use of premedication and the correct procedure to safely perform an elective (i.e., scheduled) or urgent examination. The most important recommendations are: (1) in all patients, a thorough medical history must be taken by the prescribing physician and/or the radiologist to identify at-risk patients; (2) in patients with hypersensitivity reactions to CM, the radiologist must consider an alternative, non-contrast imaging study with a comparable diagnostic value, or prescribe a different investigation with another class of CM; (3) if such options are not feasible, the radiologist must address at-risk patients to a reference centre for an allergy evaluation; (4) if timely referral to an allergist is not viable, it is recommended to use a CM other than the responsible one, taking into account cross-reactivity patterns; in the case of patients with histories of severe reactions, the presence of an anesthesiologist is also recommended and a premedication is suggested.

Multiple drug allergies: Recommendations for perioperative management

Life-threatening hypersensitivity reactions are more likely to occur in patients with a history of allergy, atopy, or asthma. Hence, in a patient who presented with a history of multiple drug allergies (MDA), an allergological assessment should be performed prior to surgical procedure. Drug allergies, being one of the causes of catastrophic events occurring in the perioperative period, are of major concern to anesthesiologists. Neuromuscular blocking agents are regularly used during anesthesia and are one of the most common causes of perioperative anaphylaxis. They are estimated to be responsible for 50%-70% of perioperative hypersensitivity reactions. Antibiotics and latex represent the next two groups of drug allergy. Allergic reactions to propofol are rare with an incidence of 1:60,000 exposures. Although intraoperative drug anaphylaxis is rare, it contributes to 4.3% of deaths occurring during general anesthesia. These recommendations discuss pathophysiology of MDA, preoperative evaluation, and anesthesia considerations as well as the prevention and management of allergic reactions in anesthetized patients with a history of MDA.

Acute Adverse Reactions to Nonionic Iodinated Contrast Media: A Meta-Analysis

OBJECTIVES

We aimed to meta-analytically compare the incidence of acute adverse reactions (AARs) to nonionic iodinated contrast media (ICM) according to the type of ICM in patients who underwent radiologic examinations with administration of ICM via intravascular route.

MATERIALS AND METHODS

A systematic literature search identified studies evaluating the incidence of AARs to 7 nonionic ICM (iobitridol, iohexol, iomeprol, iopamidol, iopromide, ioversol, and iodixanol) with extractable outcomes. These outcomes were pooled using a random-effects model, and the effect of ICM type on the incidence of overall and severe AARs was evaluated using meta-regression analysis.

RESULTS

Thirty studies with 1,360,488 exposures to ICM were included. The pooled incidences of overall and severe AARs to nonionic ICM were 1.03% (95% confidence interval [CI], 0.81%-1.30%; I = 0.99) and 0.0141% (95% CI, 0.0108%-0.0183%; I = 0.56), respectively. Iomeprol had the highest overall AAR incidence (1.74%; 95% CI, 0.79%-3.76%; I = 0.99), followed by iohexol (1.21%; 95% CI, 0.67%-2.17%; I = 0.99), iopamidol (1.10%; 95% CI, 0.60%-2.03%; I = 0.99), ioversol (0.88%; 95% CI, 0.43%-1.83%; I = 0.96), iodixanol (0.85%; 95% CI, 0.36%-1.95%; I = 0.99), iopromide (0.82%; 95% CI, 0.43%-1.55%; I = 0.99), and iobitridol (0.77%; 95% CI, 0.36%-1.62%; I = 0.99). Multivariable meta-regression analysis revealed that study design (P = 0.0014) and premedication (P = 0.0230) were statistically significant determinants affecting the incidence of overall AARs. Iodinated contrast media type did not affect the incidence of overall and severe AARs (P = 0.1453 and 0.4265, each).

CONCLUSIONS

The varying pooled incidences of overall and severe AARs to specific types of nonionic ICM do not remain as significant after adjusting confounders. Our results may support nonrestriction of certain types of nonionic ICM in the context of AAR avoidance.

Immediate Reactions to Fluorescein and Indocyanine Green in Retinal Angiography: Review of Literature and Proposal for Patient's Evaluation

Introduction

Contrast rapid sequence angiography with fluorescein or indocyanine green (ICG) is a diagnostic procedure commonly used in ophthalmology. Adverse reactions to fluorescein and ICG are rare and may be classified as toxic, of hypersensitivity and non-specific. The evaluation and management of a patient with an adverse reaction is a challenge for the majority of ophthalmologists, as is the assessment of risk factors that may contraindicate the procedure.

Purpose

We aim to review the concepts underlying adverse reactions to fluorescein and ICG, especially those of hypersensitivity, and present a proposal or the evaluation of the patients in need to perform retinal angiography and for the treatment of immediate reactions to fluorescein and ICG.

Methods

The available literature was examined using PubMed-Medline, and using the MeSH terms "fluorescein", "Indocyanine green", "ophthalmic dyes", "retinal angiography", "adverse reactions", and "allergic reaction".

Conclusion

This review may help ophthalmologists to identify patients with higher risk of a hypersensitivity reaction and give them tools to recognize patients with suspected hypersensitivity that may benefit from an allergy study.

Late-onset acute respiratory distress syndrome induced by a gadolinium-based contrast agent

Rapid decline of pulmonary function in acute respiratory distress syndrome (ARDS) can make ARDS a dangerous and potentially life-threatening condition. Gadolinium-based contrast agents are considered safe alternatives to iodine-based contrast agents, with comparatively fewer adverse effects and a lower incidence of serious adverse events, such as dyspnea or hypotension. There are five reported cases of gadolinium-induced ARDS. A 59-year-old woman with respiratory failure 30 min after gadolinium administration was diagnosed with ARDS; she was admitted to the intensive care unit. Her condition improved by artificial respiration management and adrenaline and steroids administration. She was discharged on day 13. Considering ARDS occurred 30 min after gadolinium administration and findings suggesting anaphylaxis, such as wheezing and failure in organs other than the lungs, were absent, the involvement of any immediate-onset reaction was excluded; thus, a diagnosis of gadolinium-induced ARDS was made.

Adverse reactions during procedures: Hypersensitivity to contrast agents and dyes

OBJECTIVE

This review provides an overview of the literature on hypersensitivity reactions during procedures to commonly used contrast agents and dyes. A synthesis of current knowledge on clinical symptoms, epidemiology and risk factors, pathomechanism, and management of hypersensitivity reactions to these substances is presented.

DATA SOURCES

A literature search was conducted through Medline. Included were peer-reviewed articles written in English between 2000 and 2019.

STUDY SELECTIONS

Relevant clinical studies, experimental studies, and review articles have been selected. Additionally, case reports have been included if they carried significant information about rare clinical forms of hypersensitivity reactions, disease mechanisms, or therapy.

RESULTS

An allergological workup is only indicated for patients with a history of immediate (IHR) and nonimmediate hypersensitivity reactions (NIHR) but not for toxic or unrelated adverse events. Skin tests with or without experimental cellular laboratory tests in patients with previous reactions can provide evidence for an allergic mechanism. Positive skin tests indicating allergy are more common in severe reactions. If the adverse event was allergic, skin testing of alternatives is helpful for the selection of other contrast agents for future procedures. Premedication alone may be insufficient in these cases, and breakthrough reactions occur. For nonallergic reactions, change of contrast agent and premedication is often but not always sufficient to suppress reactions.

CONCLUSION

Patients with previous NIHR or IHR, especially moderate and severe IHR, needing potential re-administration of contrast agents should be skin tested to identify an allergic mechanism as well as alternative agents to be used for future procedures.

Relationship between Lower Dose and Injection Speed of Iodinated Contrast Material for CT and Acute Hypersensitivity Reactions: An Observational Study

BackgroundThere are few data on the relationship between acute hypersensitivity reactions and the dose and injection rate of iodinated contrast material for CT.PurposeTo determine the relationship between lower dose and injection speed of iodinated contrast material for CT and the rate of acute hypersensitivity reactions.Materials and MethodsThis retrospective study included adults (age ≥18 years) undergoing nonionic iodinated contrast material-enhanced abdominal CT between August 2016 and January 2017 (control period) and between August 2017 and January 2018 (intervention period); all examinations were conducted in an outpatient setting. Compared with CT during the control period, CT during the intervention period involved a reduced dose of contrast material achieved by lowering the CT tube voltage. CT examinations in the control period were performed with 120 kVp, a contrast material dose of 2 mL/kg (maximum, 150 mL), and an injection speed of 3 or 4 mL/sec. CT examinations in the intervention period were performed with 100 kVp, a contrast material dose of 1.5 mL/kg (maximum, 130 mL), and an injection speed of 2.5 or 3 mL/sec. Per-examination rates of acute hypersensitivity reactions to iodinated contrast material were compared between the control and intervention periods with use of a multivariable Poisson regression model, the parameters of which were estimated by using generalized estimating equations with an independence correlation structure.ResultsA total of 21947 adults (mean age ± standard deviation, 59 years ± 12; 8797 women [40%]) underwent 25119 CT examinations during the control period; 23019 adults (mean age, 59 years ± 12; 9538 women [41%]) underwent 26491 CT examinations during the intervention period. The rate of acute hypersensitivity reactions was 1.42% (376 of 26491 examinations; 95% confidence interval [CI]: 1.28%, 1.57%) in the intervention period and 1.86% (468 of 25119 examinations; 95% CI: 1.70%, 2.04%) in the control period, with a multivariable-adjusted relative risk of 0.85 (95% CI: 0.74, 0.99; P = .03).ConclusionReduction in the dose and injection speed of iodinated contrast material for CT was associated with a lower rate of acute hypersensitivity reactions to iodinated contrast material.© RSNA, 2019Online supplemental material is available for this article.

Premedication for Iodinated Contrast Media Induced Immediate Hypersensitivity Reactions

Purpose of the review

Premedication using antihistamines and/or corticosteroids has been widely used to prevent reoccurrence of immediate hypersensitivity reactions (iHR) after iodinated contrast media (ICM). However, efficacy has been debated, especially in high-risk patients. Novel findings on the role and risks of premedication and preventive strategies are summarized.

Recent findings

The rate and severity of iHR occurring despite premedication indicate that premedication is not a panacea and the intensity usually reflects that of the initial reaction. Next, the number needed to treat (NNT) to prevent one serious ICM-mediated event using corticosteroid-based premedication is high and associated with a diagnostic delay. Randomly changing the ICM has been suggested as an additional preventive measure, whilst others used a skin test–based approach to identify a subgroup of ICM allergic patients and negative skin test–based alternatives with a high negative predictive value.

Summary

Growing evidence indicates the need to discriminate between non-allergic iHR that are most likely non-obligatory and susceptible to premedication, and rare type I allergic iHR that can be identified using skin testing, especially in those with a severe iHR. Although premedication reduces reoccurrence of mild iHR, it is not always efficacious and should be balanced against side effects, a high NNT and an uncertain efficacy physicians should not blindly rely on. Future work should evaluate combined approaches of an allergy-driven ICM selection and endotype-driven premedication regimens in patients with non-allergic iHR.

A mast-cell-specific receptor mediates Iopamidol induced immediate IgE-independent anaphylactoid reactions

Iopamidol is a radiographic contrast media which caused a very high incidence of anaphylactic reactions. Mast cells are sentinel cells in host defense reactions during immediate hypersensitivity responses and anaphylactic responses. Mas-related G protein-coupled receptor X2 (MRGPRX2) is a kind of mast cell specific receptor, which triggers mast cell degranulation in anaphylactic reactions. Mice MrgprB2 is a homologous gene of MRGPRX2. We sought to better understand the anaphylactic reactions induced by Iopamidol and the mechanisms involving MRGPRX2. The MRGPRX2-related anaphylactic reactions induced by Iopamidol were investigated using the hindpaw swelling and extravasation assay in vivo and a calcium imaging assay was used for mast cell intracellular calcium responses detection and mast cell release of anaphylactic mediators, such as β-hexosaminidase, histamine and TNF-α, was also detected in vitro. The mast cell deficient Kit^W-sh/W-sh mice and MrgprB2 knockout mice exhibited a reduced Iopamidol-induced inflammation effect compared with wild type mice. Furthermore, human mast cells that express MRGPRX2 were activated by Iopamidol in a dose-dependent manner, meanwhile MRGPRX2 knockdown mast cells showed reduced intracellular calcium responses and anaphylactic mediators release effect. It could be concluded that Iopamidol-induced anaphylactoid reactions were MRGPRX2 mediated to provoke mast cells Ca²⁺ mobilization and degranulation.

Recognition and management of dermatologic complications from interventional radiology procedures

A variety of dermatologic complications can occur after interventional radiology procedures, including fluoroscopy-induced radiation dermatitis, thermal skin injury from tumor ablation, non-target embolization to the skin, allergic reactions related to interventional radiology procedures, and dermatitis and infections at catheter sites. Yet, interventional radiologists typically lack training in dermatology. This review focuses on recognition of dermatologic complications and introduces basic principles for management of these complications. By taking a more active role in the diagnosis, management, and follow-up of dermatologic complications, interventional radiologists can improve the care for patients suffering iatrogenic skin inury.

Diagnosing Recurrent DVT of the Leg by Two Different Non-Contrast-Enhanced Magnetic Resonance Direct Thrombus Imaging Techniques: A Pilot Study

Introduction  Magnetic resonance direct thrombus imaging (MRDTI) is a promising technique to improve the diagnostic management of patients with a suspected ipsilateral recurrent deep vein thrombosis (DVT) by direct visualization of a thrombus. Another magnetic resonance imaging (MRI) technique, T1-weighted turbo spin-echo spectral attenuated inversion recovery (TSE-SPAIR), has the potential to image a thrombus directly with a high spatial resolution as well. The main aim of this pilot study was to investigate if adding the TSE-SPAIR sequence to an MRDTI sequence performed in patients with suspected recurrent DVT may increase the diagnostic confidence of expert MRDTI readers.

Methods  Fifteen patients with suspected acute recurrent DVT were included in this study. The TSE-SPAIR sequence was scanned directly after the MRDTI scan but not used to guide clinical decision making, and both scans were adjudicated post hoc two times separately by three independent expert MRDTI readers. Diagnostic confidence was scored on a 4-point Likert scale: (1) poor (definite diagnosis impossible), (2) fair (evaluation of major findings possible), (3) good (definite diagnosis possible), and (4) excellent (exact diagnosis possible).

Results  The diagnostic confidence of expert readers increased when adding the TSE-SPAIR sequence on top of the MRDTI sequence from “good” (median, 3.0; interquartile range [IQR], 2.66–3.0) to “excellent” (median, 3.67; IQR 3.33–3.67; p  = 0.001). Evaluation of the scans in the reversed order 5 months after initial reading showed similar results. Diagnostic accuracy for proximal DVT of both scan techniques was good.

Conclusion  The extra TSE-SPAIR sequence may help increase diagnostic confidence of radiologists in cases of uncertain diagnosis in patients with suspected ipsilateral recurrent DVT.

Controversies in Drug Allergy: Radiographic Contrast Media

The risk for developing immediate or delayed hypersensitivity reactions to radiocontrast media (RCM) interferes with the diagnosis and treatment of a number of patients requiring imaging diagnostic methods for many common diseases. A group of experts met in Orlando, Florida, in March 2018 to analyze the similarities and differences in the management of RCM reactions in different areas of the world. This paper presents a summary of the recommendations provided by this consensus group, highlighting controversial issues and unmet needs that require further research.

Acute respiratory distress syndrome after the use of gadolinium contrast agent

Acute respiratory distress syndrome (ARDS) is a life-threatening medical emergency. The etiology of ARDS can involve various causes. ARDS associated with the use of iodinated contrast media is rarely reported, and the literature includes only one case of ARDS due to gadobutrol. A 46-year-old female patient presented to our emergency department with shortness of breath, wheezing, swelling of the lips, and difficulty swallowing about 30 minutes after undergoing magnetic resonance imaging with 6.5 ml (0.1 ml/kg) gadobutrol (Gadovist) contrast for a submandibular mass. She was treated for anaphylaxis, then immediately evaluated using chest x-ray and arterial blood gas analysis. Based on the findings, she was diagnosed with ARDS and started on continuous positive airway pressure (CPAP) ventilatory support and methylprednisolone at a dose of 1 mg/kg/day. On day 3 of follow-up, all symptoms had completely regressed.

[Imaging diagnostic methods for identification of sentinel lymph nodes in patients with early squamous cell carcinoma of the oral cavity mucosa: a literature review]

The paper describes properties of clinical visualization approaches which are applied for detection of sentinel lymph nodes in patients suffering from oral cavity squamous cell cancer. Diagnostic efficiency results and technological features of different imaging techniques are discussed.

Radiographic and magnetic resonances contrast agents: Essentials and tips for safe practices

With extended and continued expansion of medical imaging utilization in modern medical practice over last decade, radiologists as well as other faculty staff dealing with radiographic and magnetic resonances contrast media (CM) have to be well oriented with their potential hypersensitivity reactions and recognize high-risk groups liable to develop it and enable early recognition. Radiologists and other medical staff involved in administration and dealing with CM have to be ready to implement prompt, practical and effective management plan to deal with these scenarios should they emerge. Strategies to prevent potential contrast-induced acute and delayed renal injuries have to be routinely exercised. Paying attention to the pregnant and nursing women, pediatrics, diabetics, as well as other fragile populations is of utmost importance for patient safety during contrast administrations. Radiologists should play a pivotal role in orienting patients about necessity to use CM for their imaging studies, in case it is needed, and assure them about its safety. Moreover, they have to be oriented with the medico-legal issues related to use of CM. These will pay as improved patient safety as well as safe daily working environmentat different levels of radiology practices.

Pro and Contra: Provocation Tests in Drug Hypersensitivity

Drug provocation test (DPT) is the controlled administration of a drug to diagnose immune- or non-immune-mediated drug hypersensitivity and the last step for accurate recognition of drug hypersensitivity reactions when the previous diagnostic evaluations are negative or unavailable. A DPT is performed only if other conventional tests fail to yield conclusive results. In each clinical presentation, "to provoke or not to provoke" a patient should be decided after careful assessment of the risk-benefit ratio. Well-defined benefits of DPT include confirmative exclusion of diagnoses of drug hypersensitivity and provision of safe alternatives. However, disadvantages such as safety, difficulty in interpretations of results, lack of objective biomarkers, risks of resensitization, efficiency in daily practice, and lack of standardized protocols, are poorly debated. This review summarizes the current published research concerning DPT, with particular emphasis on the advantages and disadvantages of DPT in an evidence-based manner.

What Does the Boxed Warning Tell Us? Safe Practice of Using Ferumoxytol as an MRI Contrast Agent

BACKGROUND AND PURPOSE

Despite the label change and the FDA's boxed warning added to the Feraheme (ferumoxytol) label in March 2015, radiologists have shown increasing interest in using ferumoxytol as an MR imaging contrast agent as a supplement or alternative to gadolinium. The goals of this study were to provide information regarding ferumoxytol safety as an imaging agent in a single center and to assess how the Feraheme label change may affect this potential, currently off-label indication.

MATERIALS AND METHODS

This retrospective study evaluated the overall frequency of ferumoxytol-related adverse events when used for CNS MR imaging. Patients with various CNS pathologies were enrolled in institutional review board-approved imaging studies. Ferumoxytol was administered as multiple rapid bolus injections. The risk of adverse events was correlated with demographic data/medical history.

RESULTS

The safety of 671 ferumoxytol-enhanced MR studies in 331 patients was analyzed. No anaphylactic, life-threatening, or fatal (grade 4 or 5) adverse events were recorded. The overall proportion of ferumoxytol-related grade 1-3 adverse events was 10.6% (8.6% occurring within 48 hours), including hypertension (2.38%), nausea (1.64%), diarrhea (1.04%), and headache (1.04%). History of 1 or 2 allergies was associated with an increased risk of adverse events (14.61% versus 7.51% [no history]; P = .007).

CONCLUSIONS

The frequency of mild ferumoxytol-related adverse events was comparable with literature results, and no serious adverse event was recorded. Although the recommendations in the boxed warning should be followed, serious adverse events appear to be rare, and with proper precautions, ferumoxytol may be a valuable MR imaging agent.

Successful desensitization to radiocontrast media in two high-risk cardiac patients

Hypersensitivity reactions to radiocontrast media (RCM) are common and in severe cases may present a challenge for treating physician in cases when premedication fails or the patient presents with severe comorbidities. We describe two cases in need of radiocontrast media after a severe reaction on previous exposure to iohexol. One presented anaphylactic reaction to RCM despite premedication and another presented with angina. Both cases were treated with a desensitization protocol to iodixanol. In conclusion, desensitization to radiocontrast media may be considered in patients with previously unsuccessful premedication and/or severe acute comorbidities.

SIMILAR CASES PUBLISHED

14.

Use of Nanoparticle Contrast Agents for Cell Tracking with Computed Tomography

Efforts to develop novel cell-based therapies originated with the first bone marrow transplant on a leukemia patient in 1956. Preclinical and clinical examples of cell-based treatment strategies have shown promising results across many disciplines in medicine, with recent advances in immune cell therapies for cancer producing remarkable response rates, even in patients with multiple treatment failures. However, cell-based therapies suffer from inconsistent outcomes, motivating the search for tools that allow monitoring of cell delivery and behavior in vivo. Noninvasive cell imaging techniques, also known as cell tracking, have been developed to address this issue. These tools can allow real-time, quantitative, and long-term monitoring of transplanted cells in the recipient, providing insight on cell migration, distribution, viability, differentiation, and fate, all of which play crucial roles in treatment efficacy. Understanding these parameters allows the optimization of cell choice, delivery route, and dosage for therapy and advances cell-based therapy for specific clinical uses. To date, most cell tracking work has centered on imaging modalities such as MRI, radionuclide imaging, and optical imaging. However, X-ray computed tomography (CT) is an emerging method for cell tracking that has several strengths such as high spatial and temporal resolution, and excellent quantitative capabilities. The advantages of CT for cell tracking are enhanced by its wide availability and cost effectiveness, allowing CT to become one of the most popular clinical imaging modalities and a key asset in disease diagnosis. In this review, we will discuss recent advances in cell tracking methods using X-ray CT in various applications, in addition to predictions on how the field will progress.

Incidence and Risk Factors for Gadolinium-Based Contrast Agent Immediate Reactions

Since their clinical introduction in 1988, gadolinium-based contrast agents (GBCAs) have demonstrated an excellent safety profile with a reported acute adverse reaction rate ranging from 0.01% to 2%. By comparison, the acute adverse reaction rate of low osmolar nonionic computed tomography contrast agents (CTCs) ranges from 0.7% to 3.1%. Many of the risk factors associated with CTC reactions (drug allergies, asthma, atopy, prior contrast reaction) also point toward an increased incidence of acute adverse events to GBCAs. With CTCs, an increased adverse event rate was associated with ionic preparations and high osmolality. In response to concerns for nephrogenic systemic fibrosis, GBCAs are now selected for their augmented chemical stability. These agents possess some combination of macrocyclic chelates or ionic preparations. With their improved chemical stability, these agents also possess higher osmolality and the increased potential to elicit an acute adverse reaction. In light of these concerns, researchers are now focusing greater efforts on reexamining acute adverse reactions to GBCAs and whether there is an increased association with certain agents. In addition to hypersensitivity reactions, this article will also discuss contrast extravasations, safety of GBCAs for pregnant and nursing patients, and the potential nephrotoxic effects of GBCAs.

Anaesthetic hypersensitivity reactions in France between 2011 and 2012: the 10th GERAP epidemiologic survey

BACKGROUND

Immediate hypersensitivity reactions during anaesthesia are rare but potentially life-threatening. The epidemiology changes with time and evolving professional practice, and hence needs to be monitored. Our objective was to follow this epidemiology.

METHODS

This was a retrospective, observational study in French hospital clinics, conducted by GERAP members (Groupe d'Étude des Réactions Anaphylactoïdes Périopératoires). Consecutive patients seen in allergo-anaesthesia outpatient clinics, who had experienced a hypersensitivity reaction during anaesthesia between 1 January 2011 and 31 December 2012, were included. Demographic data, allergy history, drugs received before the reaction, symptoms of the reaction, results of blood samples (histamine, tryptase, IgE-specific assays), and results of the allergy assessment were recorded.

RESULTS

The most common causes of allergic reactions were (Neuromuscular Blocking Agents) NMBAs (N = 302; 60.6%), antibiotics (N = 91, 18.2%, Cephalosporin N = 49, 10%) and dyes (N = 27; 5.4%). Latex as an allergic agent was involved in 26 cases (5.2%), hypnotics in 11 cases (2.2%) and opioids in seven cases (1.4%). Of the NMBAs, Rocuronium had the highest proportion of reactions (13.8 reactions/100,000 vials sold) followed by Suxamethonium (13.3/100,000 vials sold). Cisatracurium had the lowest proportion of reactions (0.4/100,000 vials sold). Patients were sensitized to two or more NMBAs in 48.9% of cases and without testing, cross-sensitivity cannot be predicted.

CONCLUSIONS

When compared with the previous GERAP studies, NMBAs are still the most frequently triggering allergens, with marked differences between individual NMBAs, but they are now followed by antibiotics (of which greater than 50% were cephalosporins) and dyes. Anaesthetists must be aware of the differences between drugs and of the pattern of emerging allergens. For the future of safe anaesthesia, allergy assessment is essential.

Stratified premedication strategy for the prevention of contrast media hypersensitivity in high-risk patients

BACKGROUND

Although the severity of hypersensitivity reactions to iodinated contrast media varies, it is well correlated with the severity of recurrent reactions; however, prophylaxis protocols are not severity-stratified.

OBJECTIVE

To assess the outcomes of tailored prophylaxis according to the severity of hypersensitivity reactions to iodinated contrast media.

METHODS

Our premedication protocols were stratified based on the severity of previous reactions: (1) 4 mg of chlorpheniramine for mild reactions, (2) adding 40 mg of methylprednisolone for moderate reactions, and (3) adding multiple doses of 40 mg of methylprednisolone for severe index reactions. Cases of reexposure in patients with a history of hypersensitivity reactions were routinely monitored and mandatorily recorded.

RESULTS

Among a total of 850 patients who underwent enhanced computed tomography after severity-tailored prophylaxis, breakthrough reactions occurred in 17.1%, but most breakthrough reactions (89.0%) were mild and did not require medical treatment. Additional corticosteroid use did not reduce the breakthrough reaction rate in cases with a mild index reaction (16.8% vs 17.2%, P = .70). However, underpremedication with a single dose of corticosteroid revealed significantly higher rates of breakthrough reaction than did double doses of corticosteroid in cases with a severe index reaction (55.6% vs 17.4%, P = .02). Changing the iodinated contrast media resulted in an additional reduction of the breakthrough reaction rate overall (14.9% vs 32.1%, P = .001).

CONCLUSION

In a total severity-based stratified prophylaxis regimens and changing iodinated contrast media can be considered in patients with a history of previous hypersensitivity reaction to iodinated contrast media to reduce the risk of breakthrough reactions.