British journal of anaesthesia
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Randomized Controlled Trial
Knowledge retention after simulated crisis: importance of independent practice and simulated mortality.
Simulation is an important component of postgraduate medical education, but optimal parameters for simulation are not known. Managing simulations independently and allowing simulated morbidity and mortality have been shown to improve follow-up performance in simulation. We hypothesised that allowing simulated mortality improves performance in follow-up simulations more than independent practice. ⋯ Independence and the potential for simulated mortality have a greater impact on performance in follow-up simulations when combined than either factor alone.
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Around 10-15% of the in-patient population carry unsubstantiated 'penicillin allergy' labels, the majority incorrect when tested. These labels are associated with harm from use of broad-spectrum non-penicillin antibiotics. Current testing guidelines incorporate both skin and challenge tests; this is prohibitively expensive and time-consuming to deliver on a large scale. We aimed to establish the feasibility of a rapid access de-labelling pathway for surgical patients, using direct oral challenge. ⋯ ClinicalTrials.gov: AN17/92982.
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This thorough review of the global epidemiology of perioperative hypersensitivity (POH), reflects our increasing awareness that anaphylaxis varies geographically.
Incidence
Reported incidence ranges from 1 in 18,600 to 1 in 353, although NAP6 (UK) and French studies independently estimate life-threatening anaphylaxis at 1 in 10,000.
Mortality
Anaphylaxis mortality was generally ~4% (UK, France, USA, Japan), although Western Australian data estimated a lower range of 0-1.4%.
Causal agents
Implicated agents commonly include neuromuscular blocking drugs (1st or 2nd commonest in most studies), although the higher incidence seen with specific NMBDs (eg. Sux and Roc) appears to occur in some regions but not others. Pholcodine has been implicated as causative in these regional differences.
Sugammadex has increasingly been implicated as a cause of POH, though notably also with regional variation. A dose-related effect has also been reported.
Antibiotics are an increasingly common cause of POH, in particular β-lactams. Nevertheless, ‘pan-β-lactam allergy’ is probably rare, and some examples like cefazolin, have limited cross-reactivity.
“Cefazolin does not share an R1 and R2 group with any other β-lactam...”
Latex POH is declining, while chlorhexidine is increasing (9% in NAP6, with significant regional variability), albeit often as a ‘hidden’ precipitant.
Surgical dyes (patent blue V, isosulfan blue, methylene blue) are also increasingly common causes of POH (4th most common in NAP6 (~1 in 7,000), 3rd in France).
Less common POH causes include povodine-iodine and colloids.
Hypnotics, local anaesthetic, aprotinin, protamine and NSAIDs are very uncommon-to-rare causes of POH. Opioids are sometimes implicated via the MRGPRX2 receptor, although true opioid IgE-mediated hypersensitivity is very rare.
Bottom-line
The wide geographic variations in anaphylaxis incidence and causation reveal a complex interplay of genetics and environment, along with our evolving understanding of the complexity of anaphylaxis.
Go deeper...
Read Florvaag & Johansson’s seminal article The Pholcodine Story for an intriguing story of geographic POH differences.
summary -
Chlorhexidine is an antiseptic with a broad spectrum of activity and a persistent effect on skin. Consequently, it has become an ubiquitous antiseptic in healthcare and the community. As use has become widespread, increasing numbers of cases of allergy have been reported in the literature, including cases of anaphylaxis to chlorhexidine gels used on mucous membranes, chlorhexidine-impregnated devices such as central venous catheters, chlorhexidine preparations used on wounds and broken skin, and cases after dental procedures. ⋯ Sensitisation of healthcare workers can occur, but is uncommon. Before exposing patients to this antiseptic, consideration of the potential risk vs benefit should be undertaken, particularly for higher risk exposures, such as mucosal exposure or i.v. exposure via impregnated lines. Difficulties exist in protecting patients with known allergies from re-exposure to chlorhexidine, which would be improved with uniform labelling and chlorhexidine product registers.
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Unsubstantiated penicillin-allergy labels are common in surgical patients, and can lead to significant harm through avoidance of best first-line prophylaxis of surgical site infections and increased infection with resistant bacterial strains. Up to 98% of penicillin-allergy labels are incorrect when tested. ⋯ A variety of healthcare professionals can, with appropriate training and in collaboration with allergists, provide testing for selected patients. We review how patients might be assessed, the appropriate testing strategies that can be used, and the minimum standards of safe testing.