Malignant hyperthermia 2020: Guideline from the Association of Anaesthetists.

Malignant hyperthermia is defined in the International Classification of Diseases as a progressive life-threatening hyperthermic reaction occurring during general anaesthesia. Malignant hyperthermia has an underlying genetic basis, and genetically susceptible individuals are at risk of developing malignant hyperthermia if they are exposed to any of the potent inhalational anaesthetics or suxamethonium. It can also be described as a malignant hypermetabolic syndrome. There are no specific clinical features of malignant hyperthermia and the condition may prove fatal unless it is recognised in its early stages and treatment is promptly and aggressively implemented. The Association of Anaesthetists has previously produced crisis management guidelines intended to be displayed in all anaesthetic rooms as an aide memoire should a malignant hyperthermia reaction occur. The last iteration was produced in 2011 and since then there have been some developments requiring an update. In these guidelines we will provide background information that has been used in updating the crisis management recommendations but will also provide more detailed guidance on the clinical diagnosis of malignant hyperthermia. The scope of these guidelines is extended to include practical guidance for anaesthetists dealing with a case of suspected malignant hyperthermia once the acute reaction has been reversed. This includes information on care and monitoring during and after the event; appropriate equipment and resuscitative measures within the operating theatre and ICU; the importance of communication and teamwork; guidance on counselling of the patient and their family; and how to make a referral of the patient for confirmation of the diagnosis. We also review which patients presenting for surgery may be at increased risk of developing malignant hyperthermia under anaesthesia and what precautions should be taken during the peri-operative management of the patients.

Skin cancer multiplicity in lung transplant recipients: a prospective population-based study.

BACKGROUND: Lung transplant recipients are at high risk of skin cancer, but precise annual incidence rates of treated skin cancers per patient are unknown. OBJECTIVES: To perform a prospective assessment of the total burden of histologically confirmed squamous cell carcinoma (SCC) and basal cell carcinoma (BCC) and associated factors in lung transplant recipients. METHODS: A population-based cohort of 125 Queensland lung transplant recipients aged 18 years and over, recruited between 2013 and 2015, were followed to the end of 2016. All underwent dermatological skin examinations at baseline and annually thereafter and patients self-reported all interim treated skin cancers, which were verified against pathology databases. Standard skin cancer risk factors were obtained via questionnaire, and details of medications were acquired from hospital records. RESULTS: During a median follow-up time of 1·7 years, 29 (23%) and 30 (24%) lung transplant recipients with a median duration of immunosuppression of 3·3 years developed SCC and BCC, respectively. The general population age-standardized incidence rates of SCC and BCC were 201 and 171 per 1000 person-years, respectively (based on first primary SCC or BCC during follow-up); however, on accounting for multiple primary tumours, corresponding incidence rates were 447 and 281 per 1000 person-years. Risk of multiple SCCs increased around sixfold in those aged ≥ 60 years and in those with previous skin cancer, and increased around threefold in those treated with the antifungal medication voriconazole. Multiple BCC risk rose threefold from age 60 years and tenfold for patients with previous skin cancer. CONCLUSIONS: Lung transplant recipients have very high incidence of multiple primary skin cancers. Close surveillance and assiduous prevention measures are essential. Linked Comment: Proby and Harwood. Br J Dermatol 2020; 183:416-417.

Penicillin allergy de-labelling ahead of elective surgery: feasibility and barriers.

BACKGROUND: 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. METHODS: 'Penicillin allergic' patients, recruited from a surgical pre-assessment clinic, were risk-stratified using a screening questionnaire. Patients at low risk of true, immunoglobulin E (IgE)-mediated allergy were offered direct oral challenge using incremental amoxicillin to a total dose of 500 mg. A 3-day course was completed at home. De-labelled patients were followed up to determine antibiotic use in surgery, and attitudes towards de-labelling were explored. RESULTS: Of 219 patients screened, 74 were eligible for inclusion and offered testing. We subsequently tested 56 patients; 55 were de-labelled. None had a serious reaction to the supervised challenge, or thereafter. On follow-up, 17 of 19 patients received appropriate antimicrobial prophylaxis during surgery. Only three of 33 de-labelled patients would have been happy for the label to be removed without prior specialist testing. CONCLUSION: Rapid access de-labelling, using direct oral challenge in appropriately risk-stratified patients, can be incorporated into the existing surgical care pathway. This provides immediate and potential long-term benefit for patients. Interest in testing is high among patients, and clinicians appear to follow clinic recommendations. Patients are unlikely to accept removal of their allergy label on the basis of history alone. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov: AN17/92982.

Management of a surgical patient with a label of penicillin allergy: narrative review and consensus recommendations.

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. Because of the scarcity of trained allergists in all healthcare systems, only a minority of surgical patients have the opportunity to undergo testing and de-labelling before surgery. Testing pathways can be modified and shortened in selected patients. 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.

Consensus clinical scoring for suspected perioperative immediate hypersensitivity reactions.

BACKGROUND: Grading schemes for severity of suspected allergic reactions have been applied to the perioperative setting, but there is no scoring system that estimates the likelihood that the reaction is an immediate hypersensitivity reaction. Such a score would be useful in evaluating current and proposed tests for the diagnosis of suspected perioperative immediate hypersensitivity reactions and culprit agents. METHODS: We conducted a Delphi consensus process involving a panel of 25 international multidisciplinary experts in suspected perioperative allergy. Items were ranked according to appropriateness (on a scale of 1-9) and consensus, which informed development of a clinical scoring system. The scoring system was assessed by comparing scores generated for a series of clinical scenarios against ratings of panel members. Supplementary scores for mast cell tryptase were generated. RESULTS: Two rounds of the Delphi process achieved stopping criteria for all statements. From an initial 60 statements, 43 were rated appropriate (median score 7 or more) and met agreement criteria (disagreement index <0.5); these were used in the clinical scoring system. The rating of clinical scenarios supported the validity of the scoring system. Although there was variability in the interpretation of changes in mast cell tryptase by the panel, we were able to include supplementary scores for mast cell tryptase. CONCLUSION: We used a robust consensus development process to devise a clinical scoring system for suspected perioperative immediate hypersensitivity reactions. This will enable objectivity and uniformity in the assessment of the sensitivity of diagnostic tests.

Malignant hyperthermia, environmental heat stress, and intracellular calcium dysregulation in a mouse model expressing the p.G2435R variant of RYR1.

BACKGROUND: The human p.G2434R variant of the RYR1 gene is most frequently associated with malignant hyperthermia (MH) in the UK. We report the phenotype of a knock-in mouse that expresses the RYR1 variant p.G2435R, which is isogenetic with the human variant. METHODS: We observed the general phenotype; determined the sensitivity of myotubes to caffeine-, KCl, and halothane-induced Ca2+ release; determined the in vivo response to halothane or increased ambient temperature; and determined the in vivo myoplasmic intracellular Ca2+ concentration in skeletal muscle before and during exposure to volatile anaesthetics. RESULTS: RYR1 pG2435R/MH normal (MHS-Heterozygous[Het]) or RYR1 pG2435R/pG2435R (MHS-Homozygous[Hom]) mice were fully viable under typical rearing conditions, although some male MHS-Hom mice died spontaneously. The normalised half-maximal effective concentration (95% confidence interval) for intracellular Ca2+ release in myotubes in response to KCl [MH normal, MHN, 21.4 (19.8-23.1) mM; MHS-Het 16.2 (15.2-17.2) mM; MHS-Hom 11.2 (10.2-12.2) mM] and caffeine (MHN, 5.7 (5-6.3) mM; MHS-Het 4.5 (3.9-5.0) mM; MHS-Hom 1.77 (1.5-2.1) mM] exhibited a gene dose-dependent decrease, and there was a gene dose-dependent increase in halothane sensitivity. Intact animals show a gene dose-dependent susceptibility to MH with volatile anaesthetics or to heat stroke. RYR1 p.G2435R mice had elevated skeletal muscle intracellular resting [Ca2+]i, (values are expressed as mean (SD)) (MHN 123 (3) nM; MHS-Het 156 (16) nM; MHS-Hom 265 (32) nM; P<0.001) and [Na+]i (MHN 8 (0.1) mM; MHS-Het 10 (1) mM; MHS-Hom 14 (0.7) mM; P<0.001) that was further increased by exposure to volatile anaesthetics. CONCLUSIONS: RYR1 pG2435R mice demonstrated gene dose-dependent in vitro and in vivo responses to pharmacological and environmental stressors that parallel those seen in patients with the human RYR1 variant p.G2434R.

Genetic epidemiology of malignant hyperthermia in the UK.

BACKGROUND: Gaps in our understanding of genetic susceptibility to malignant hyperthermia (MH) limit the application and interpretation of genetic diagnosis of the condition. Our aim was to define the prevalence and role of variants in the three genes implicated in MH susceptibility in the largest comprehensively phenotyped MH cohort worldwide. METHODS: We initially included one individual from each positive family tested in the UK MH Unit since 1971 to detect variants in RYR1, CACNA1S, or STAC3. Screening for genetic variants has been ongoing since 1991 and has involved a range of techniques, most recently next generation sequencing. We assessed the pathogenicity of variants using standard guidelines, including family segregation studies. The prevalence of recurrent variants of unknown significance was compared with the prevalence reported in a large database of sequence variants in low-risk populations. RESULTS: We have confirmed MH susceptibility in 795 independent families, for 722 of which we have a DNA sample. Potentially pathogenic variants were found in 555 families, with 25 RYR1 and one CACNA1S variants previously unclassified recurrent variants significantly over-represented (P<1×10-7) in our cohort compared with the Exome Aggregation Consortium database. There was genotype-phenotype discordance in 86 of 328 families suitable for segregation analysis. We estimate non-RYR1/CACNA1S/STAC3 susceptibility occurs in 14-23% of MH families. CONCLUSIONS: Our data provide current estimates of the role of variants in RYR1, CACNA1S, and STAC3 in susceptibility to MH in a predominantly white European population.

Mesenchymal Stromal Cells are Readily Recoverable from Lung Tissue, but not the Alveolar Space, in Healthy Humans.

Stromal support is critical for lung homeostasis and the maintenance of an effective epithelial barrier. Despite this, previous studies have found a positive association between the number of mesenchymal stromal cells (MSCs) isolated from the alveolar compartment and human lung diseases associated with epithelial dysfunction. We hypothesised that bronchoalveolar lavage derived MSCs (BAL-MSCs) are dysfunctional and distinct from resident lung tissue MSCs (LT-MSCs). In this study, we comprehensively interrogated the phenotype and transcriptome of human BAL-MSCs and LT-MSCs. We found that MSCs were rarely recoverable from the alveolar space in healthy humans, but could be readily isolated from lung transplant recipients by bronchoalveolar lavage. BAL-MSCs exhibited a CD90Hi , CD73Hi , CD45Neg , CD105Lo immunophenotype and were bipotent, lacking adipogenic potential. In contrast, MSCs were readily recoverable from healthy human lung tissue and were CD90Hi or Lo , CD73Hi , CD45Neg , CD105Int and had full tri-lineage potential. Transcriptional profiling of the two populations confirmed their status as bona fide MSCs and revealed a high degree of similarity between each other and the archetypal bone-marrow MSC. 105 genes were differentially expressed; 76 of which were increased in BAL-MSCs including genes involved in fibroblast activation, extracellular matrix deposition and tissue remodelling. Finally, we found the fibroblast markers collagen 1A1 and α-smooth muscle actin were increased in BAL-MSCs. Our data suggests that in healthy humans, lung MSCs reside within the tissue, but in disease can differentiate to acquire a profibrotic phenotype and migrate from their in-tissue niche into the alveolar space. Stem Cells 2016;34:2548-2558.

Assessing the pathogenicity of RYR1 variants in malignant hyperthermia.

BACKGROUND: . Missense variants in the ryanodine receptor 1 gene ( RYR1 ) are associated with malignant hyperthermia but only a minority of these have met the criteria for use in predictive DNA diagnosis. We examined the utility of a simplified method of segregation analysis and a functional assay for determining the pathogenicity of recurrent RYR1 variants associated with malignant hyperthermia. METHODS: . We identified previously uncharacterised RYR1 variants found in four or more malignant hyperthermia families and conducted simplified segregation analyses. An efficient cloning and mutagenesis strategy was used to express ryanodine receptor protein containing one of six RYR1 variants in HEK293 cells. Caffeine-induced calcium release, measured using a fluorescent calcium indicator, was compared in cells expressing each variant to that in cells expressing wild type ryanodine receptor protein. RESULTS.: We identified 43 malignant hyperthermia families carrying one of the six RYR1 variants. There was segregation of genotype with the malignant hyperthermia susceptibility phenotype in families carrying the p.E3104K and p.D3986E variants, but the number of informative meioses limited the statistical significance of the associations. HEK293 functional assays demonstrated an increased sensitivity of RyR1 channels containing the p.R2336H, p.R2355W, p.E3104K, p.G3990V and p.V4849I compared with wild type, but cells expressing p.D3986E had a similar caffeine sensitivity to cells expressing wild type RyR1. CONCLUSIONS: . Segregation analysis is of limited value in assessing pathogenicity of RYR1 variants in malignant hyperthermia. Functional analyses in HEK293 cells provided evidence to support the use of p.R2336H, p.R2355W, p.E3104K, p.G3990V and p.V4849I for diagnostic purposes but not p.D3986E.

Thermoelectric and Structural Characterization of Al-Doped ZnO/Y2O3 Multilayers.

The influence of Y2O3 nanolayers on thermoelectric performance and structure of 2% Al-doped ZnO (AZO) thin films has been studied. Multilayers based on five 50 nm thick AZO layers alternated with few nanometers thick Y2O3 layers were prepared by pulsed laser deposition on Al2O3 single crystals by alternate ablation of AZO target and Y2O3 target. The number of laser shots on Y2O3 target was maintained very low (5, 10 and 15 pulses in three separate experiments. The main phase (AZO) presents polycrystalline orientation and typical columnar growth not affected by the presence of Y2O3 nanolayers. The multilayer with 15 laser shots of Y2O3 showed best thermoelectric performance with electrical conductivity σ 48 S/cm and Seebeck coefficient S = −82 µV/K, which estimate power factor (S2·σ) about 0.03 × 10−3 W m−1 K−2 at 600 K. The value of thermal conductivity (κ) was found 10.03 W m−1 K−1 at 300 K, which is one third of typical value previously reported for bulk AZO. The figure of merit, ZT = S2·σ·T/κ, is calculated 9.6 × 10−4 at 600 K. These results demonstrated the feasibility of nanoengineered defects insertion for the depression of thermal conductivity.

Posaconazole in lung transplant recipients: use, tolerability, and efficacy.

BACKGROUND: Fungal infection is a common cause of mortality and morbidity in lung transplant recipients (LuTR). Treatment failure to first-line antifungals because of resistance or intolerance is an increasing problem. Posaconazole (PCZ), a triazole antifungal, is an attractive treatment option. METHODS: We performed a single-center retrospective study to describe the use, tolerability, efficacy, and drug interaction effect (with tacrolimus) of PCZ oral suspension in LuTR. RESULTS: Seventy-eight patients were treated with PCZ oral suspension for prophylaxis (n = 15), pre-emptive treatment (n = 31), and treatment of possible (n = 7) and probable (n = 25) invasive fungal infection. A range of fungal isolates was encountered. Resolution was observed in 52.4% (probable, possible, and pre-emptive treatment groups). Aggregate all-cause 1-year mortality was 12.8%. PCZ was well tolerated with 11.5% of patients experiencing adverse effects. Despite dose adjustment strategies, 11.7% of patients experienced supratherapeutic tacrolimus levels, which in 5 cases was associated with a rise (mean 21.6 µmol/L) in serum creatinine. CONCLUSIONS: PCZ is well tolerated and appears effective in the management of fungal infection after lung transplantation. Patients receiving concurrent tacrolimus require careful therapeutic drug monitoring.

The value of uncertainty in critical illness? An ethnographic study of patterns and conflicts in care and decision-making trajectories.

BACKGROUND: With increasingly intensive treatments and population ageing, more people face complex treatment and care decisions. We explored patterns of the decision-making processes during critical care, and sources of conflict and resolution. METHODS: Ethnographic study in two Intensive Care Units (ICUs) in an inner city hospital comprising: non-participant observation of general care and decisions, followed by case studies where treatment limitation decisions, comfort care and/or end of life discussions were occurring. These involved: semi-structured interviews with consenting families, where possible, patients; direct observations of care; and review of medical records. RESULTS: Initial non-participant observation included daytime, evenings, nights and weekends. The cases were 16 patients with varied diagnoses, aged 19-87 years; 19 family members were interviewed, aged 30-73 years. Cases were observed for <1 to 156 days (median 22), depending on length of ICU admission. Decisions were made serially over the whole trajectory, usually several days or weeks. We identified four trajectories with distinct patterns: curative care from admission; oscillating curative and comfort care; shift to comfort care; comfort care from admission. Some families considered decision-making a negative concept and preferred uncertainty. Conflict occurred most commonly in the trajectories with oscillating curative and comfort care. Conflict also occurred inside clinical teams. Families were most often involved in decision-making regarding care outcomes and seemed to find it easier when patients switched definitively from curative to comfort care. We found eight categories of decision-making; three related to the care outcomes (aim, place, response to needs) and five to the care processes (resuscitation, decision support, medications/fluids, monitoring/interventions, other specialty involvement). CONCLUSIONS: Decision-making in critical illness involves a web of discussions regarding the potential outcomes and processes of care, across the whole disease trajectory. When measures oscillate between curative and comfort there is greatest conflict. This suggests a need to support early communication, especially around values and preferred care outcomes, from which other decisions follow, including DNAR. Offering further support, possibly with expert palliative care, communication, and discussion of 'trial of treatment' may be beneficial at this time, rather than waiting until the 'end of life'.

Does regional anaesthesia improve outcome?

This review examines the recent evidence of an impact of regional anaesthesia on important clinical outcomes. Evidence was obtained from a variety of studies, with increasing numbers of analyses of large databases being prominent. The benefits and limitations of these approaches are considered in order to provide a context for interpretation of the data they generate. There should be little argument that correctly performed and appropriately used regional anaesthetic techniques can provide the most effective postoperative analgesia for the duration of the block, but the majority of studies suggest that this does not translate into improved longer-term surgical outcomes. The evidence for reduced incidence of major complications when regional anaesthesia is compared with, or added to, general anaesthesia is mixed. There appears to be a small effect in reducing blood loss during major joint arthroplasty. Some, but not all, studies demonstrate a reduced incidence of respiratory and infective complications with regional anaesthesia, but the effect on cardiovascular complications is variable. There are even some data consistent with a hypothesis that general anaesthesia may be protective against postoperative cognitive dysfunction. In conclusion, there is probably no generally applicable benefit in long-term outcomes with regional anaesthesia. More likely is an interaction between patient factors, the surgical procedure, and the relative capability of the anaesthetist to manage different types of anaesthesia.

Peripheral regional anaesthesia and outcome: lessons learned from the last 10 years.

BACKGROUND: Our aim was to review the recent evidence for the efficacy of peripheral regional anaesthesia. METHODS: Following a systematic literature search and selection of publications based on prospectively agreed upon criteria, we produced a narrative review of the most commonly performed peripheral regional anaesthetic blocks for surgery on the upper limb, the lower limb, and the trunk. We considered short-term and longer-term benefits and complications among the outcomes of interest. RESULTS: Where good quality evidence exists, the great majority of the blocks reviewed were associated with one or any combination of reduced postoperative pain, reduced opioid consumption, or increased patient satisfaction. For selected surgical procedures, the use of blocks avoided general anaesthesia and was associated with increased efficiency of the surgical pathway. The exceptions were supraclavicular block, where there was insufficient evidence, and transversus abdominis plane block, where the evidence for efficacy was conflicting. The evidence for the impact of the blocks on longer-term outcomes was, in general, inadequate to inform clinical decision making. Permanent complications are rare. CONCLUSIONS: The majority of peripheral regional anaesthetic techniques have been shown to produce benefits for patients and hospital efficiency. Further interventional trials are required to clarify such benefits for supraclavicular block and transversus abdominis plane block and to ascertain any longer-term benefits for almost all of the blocks reviewed. Permanent complications of peripheral regional anaesthetic blocks are rare but accurate estimates of their incidence are yet to be determined.

Teicoplanin allergy - an emerging problem in the anaesthetic allergy clinic.

BACKGROUND: Anaphylaxis to teicoplanin appears to be extremely rare, with only one confirmed case report worldwide. Two anaesthetic allergy clinics in the UK have received a number of suspected cases referred for investigation, and we present here the first case series of teicoplanin allergy. METHODS: We investigated 20 cases of suspected teicoplanin allergy, identified from the two clinics over a period of two years. We devised a set of five criteria to categorize the certainty of their diagnosis. These included: (1) reaction within 15 min of administration of teicoplanin, (2) ≥2 features of anaphylaxis present, (3) positive skin testing or challenge testing, (4) raised serum mast cell tryptase (MCT), (5) alternative diagnosis excluded. Based on these criteria we defined the likelihood of IgE-mediated allergy to teicoplanin as: definite-met all criteria; probable-met criteria 1.2 and 5, plus 3 or 4; uncertain-met criteria 1.2 and 5; excluded- any others. RESULTS: We identified 7 'definite', 7 'probable' and 2 'uncertain' cases of teicoplanin allergy. Four cases were excluded. CONCLUSIONS: IgE-mediated anaphylaxis to teicoplanin appears to be more common than previously thought. This is true even if only definitive cases are considered. Investigation of teicoplanin allergy is hampered by the lack of standardized skin test concentrations. In some cases, there was a severe clinical reaction, but without any skin test evidence of histamine release. The mechanism of reaction in these cases is not known and requires further study.

European Malignant Hyperthermia Group guidelines for investigation of malignant hyperthermia susceptibility.

It is 30 yr since the British Journal of Anaesthesia published the first consensus protocol for the laboratory diagnosis of malignant hyperthermia susceptibility from the European Malignant Hyperthermia Group. This has subsequently been used in more than 10 000 individuals worldwide to inform use of anaesthetic drugs in these patients with increased risk of developing malignant hyperthermia during general anaesthesia, representing an early and successful example of stratified medicine. In 2001, our group also published a guideline for the use of DNA-based screening of malignant hyperthermia susceptibility. We now present an updated and complete guideline for the diagnostic pathway for patients potentially at increased risk of developing malignant hyperthermia. We introduce the new guideline with a narrative commentary that describes its development, the changes to previously published protocols and guidelines, and new sections, including recommendations for patient referral criteria and clinical interpretation of laboratory findings.

Phaeochromocytoma [corrected] crisis.

Phaeochromocytoma [corrected] crisis is an endocrine emergency associated with significant mortality. There is little published guidance on the management of phaeochromocytoma [corrected] crisis. This clinical practice update summarizes the relevant published literature, including a detailed review of cases published in the past 5 years, and a proposed classification system. We review the recommended management of phaeochromocytoma [corrected] crisis including the use of alpha-blockade, which is strongly associated with survival of a crisis. Mechanical circulatory supportive therapy (including intra-aortic balloon pump or extra-corporeal membrane oxygenation) is strongly recommended for patients with sustained hypotension. Surgical intervention should be deferred until medical stabilization is achieved.