Correction to: A randomized, open-label, adaptive, proof-of-concept clinical trial of modulation of host thromboinflammatory response in patients with COVID-19: the DAWn-Antico study

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A randomized, open-label, adaptive, proof-of-concept clinical trial of modulation of host thromboinflammatory response in patients with COVID-19: the DAWn-Antico study

BACKGROUND

The peak of the global COVID-19 pandemic has not yet been reached, and many countries face the prospect of a second wave of infections before effective vaccinations will be available. After an initial phase of viral replication, some patients develop a second illness phase in which the host thrombotic and inflammatory responses seem to drive complications. Severe COVID-19 disease is linked to high mortality, hyperinflammation, and a remarkably high incidence of thrombotic events. We hypothesize a crucial pathophysiological role for the contact pathway of coagulation and the kallikrein-bradykinin pathway. Therefore, drugs that modulate this excessive thromboinflammatory response should be investigated in severe COVID-19.

METHODS

In this adaptive, open-label multicenter randomized clinical trial, we compare low molecular weight heparins at 50 IU anti-Xa/kg twice daily-or 75 IU anti-Xa twice daily for intensive care (ICU) patients-in combination with aprotinin to standard thromboprophylaxis in hospitalized COVID-19 patients. In the case of hyperinflammation, the interleukin-1 receptor antagonist anakinra will be added on top of the drugs in the interventional arm. In a pilot phase, the effect of the intervention on thrombotic markers (D-dimer) will be assessed. In the full trial, the primary outcome is defined as the effect of the interventional drugs on clinical status as defined by the WHO ordinal scale for clinical improvement.

DISCUSSION

In this trial, we target the thromboinflammatory response at multiple levels. We intensify the dose of low molecular weight heparins to reduce thrombotic complications. Aprotinin is a potent kallikrein pathway inhibitor that reduces fibrinolysis, activation of the contact pathway of coagulation, and local inflammatory response. Additionally, aprotinin has shown in vitro inhibitory effects on SARS-CoV-2 cellular entry. Because the excessive thromboinflammatory response is one of the most adverse prognostic factors in COVID-19, we will add anakinra, a recombinant interleukin-1 receptor antagonist, to the regimen in case of severely increased inflammatory parameters. This way, we hope to modulate the systemic response to SARS-CoV-2 and avoid disease progressions with a potentially fatal outcome.

TRIAL REGISTRATION

The EU Clinical Trials Register 2020-001739-28 . Registered on April 10, 2020.

The histopathological spectrum of malignant hyperthermia and rhabdomyolysis due to RYR1 mutations

Objective

The histopathological features of malignant hyperthermia (MH) and non-anaesthetic (mostly exertional) rhabdomyolysis (RM) due to RYR1 mutations have only been reported in a few cases.

Methods

We performed a retrospective multi-centre cohort study focussing on the histopathological features of patients with MH or RM due to RYR1 mutations (1987–2017). All muscle biopsies were reviewed by a neuromuscular pathologist. Additional morphometric and electron microscopic analysis were performed where possible.

Results

Through the six participating centres we identified 50 patients from 46 families, including patients with MH (n = 31) and RM (n = 19). Overall, the biopsy of 90% of patients showed one or more myopathic features including: increased fibre size variability (n = 44), increase in the number of fibres with internal nuclei (n = 30), and type I fibre predominance (n = 13). Abnormalities on oxidative staining, generally considered to be more specifically associated with RYR1-related congenital myopathies, were observed in 52%, and included unevenness (n = 24), central cores (n = 7) and multi-minicores (n = 3). Apart from oxidative staining abnormalities more frequently observed in MH patients, the histopathological spectrum was similar between the two groups. There was no correlation between the presence of cores and the occurrence of clinically detectable weakness or presence of (likely) pathogenic variants.

Conclusions

Patients with RYR1-related MH and RM exhibit a similar histopathological spectrum, ranging from mild myopathic changes to cores and other features typical of RYR1-related congenital myopathies. Suggestive histopathological features may support RYR1 involvement, also in cases where the in vitro contracture test is not informative.

Electronic supplementary material

The online version of this article (10.1007/s00415-019-09209-z) contains supplementary material, which is available to authorized users.

The Changing Face of Malignant Hyperthermia: Less Fulminant, More Insidious

Modern anaesthetic techniques have resulted in the clinical presentation of malignant hyperthermia to be more often indolent and/or insidious than truly fulminant, as previously known in the anaesthetic community. We present four recently referred cases to illustrate this point: one late-onset case, two patients with slowly progressive hypercapnia as the sole sign and a fourth patient with postoperative myalgias and elevated creatine kinase. We also discuss the reasons for the shift in typical clinical presentation. The more insidious character of malignant hyperthermia is most likely due to the lower triggering potency of modern volatile anaesthetics, the mitigating effects of several intravenous drugs (neuromuscular blocking agents, alpha 2 adrenergic receptor agonists, beta-adrenergic blockade) or techniques (neuraxial anaesthesia) and the routine use of end-tidal CO2 monitoring leading to the early withdrawal of triggering drugs. Awareness among anaesthetists of this change in presentation is important since the clinical diagnosis is often more doubtful and, if corroborative evidence is not sought, the diagnosis may be delayed or missed altogether.

Invasive pulmonary aspergillosis due to a multi-azole resistant Aspergillus fumigatus

A patient with invasive pulmonary aspergillosis due to an azole-resistant Aspergillus fumigatus is described. Despite treatment change from voriconazole to amphotericin B as soon as the resistance data were available, the patient died. Azole resistance is an emerging problem, which significantly complicates the management of A. fumigatus infections. It should be considered in every patient with an invasive A. fumigatus infection who is not responding to voriconazole therapy.

Delayed and prolonged coma after acute disulfiram overdose

We report the case of a 35-year-old man presenting with a delayed and prolonged coma due to an intentional overdose with disulfiram without simultaneous alcohol ingestion. The clinical features--comprising a severe toxic encephalopathy with coma and convulsions, in combination with a quadriparesis outlasting the loss of consciousness--are summarized, and the physiopathology is reviewed.

Anaesthetic considerations for patients with a pre-existing neurological deficit: are neuraxial techniques safe?

Pre-existing neurological and muscular disease may be a specific concern for anaesthetists as they need to consider the effect of anaesthesia upon the disease, vice versa, and the interaction of anaesthesia with the medication taken by the patient. Despite a lack of controlled studies, many anaesthetists, being afraid of a claim, will prefer general rather than regional anaesthesia in these patients. Nevertheless regional anaesthesia certainly merits its place because it offers undeniable advantages. A good pre-operative examination is very important while patients should also be informed about peri-operative implications of anaesthesia, surgery and stress. Paraesthesias, epinephrine and high concentrations of local anaesthetics should be avoided in the majority of the diseases. Some diseases may benefit from epidural anaesthesia while for others a spinal technique may be the technique of preference. Special attention should be paid to patients with spinal stenosis despite recent reassuring reports with respect to safety of regional anaesthetic techniques. Anaesthetists should not automatically take all responsibility in case of progressive or new deficit after the procedure.

Molecular genetic detection of susceptibility to malignant hyperthermia in Belgian families

Malignant hyperthermia is an autosomal dominant myopathy triggered by volatile anesthetics or succinylcholine in susceptible persons. While in vitro contracture testing (IVCT) is the gold standard to establish malignant hyperthermia (MH) susceptibility, genetic analysis is increasingly used to diagnose this condition. This work aimed to determine the frequency and distribution of ryanodine receptor (RYR1) mutations in the Belgian MH-population as investigated by IVCT in our centre, as well as the discordance rates between the 2 techniques. Sequence analysis of 16 RYRI-exons in 29 selected families resulted in the detection of 10 mutations (4 Gly341Arg, 2 Arg614Leu, and 1 Cys35Arg, Arg614Cys, Arg2163Cys and Arg2435His). Discordance between IVCT and mutation analysis was observed in only 6 out of 96 individuals from 4 different families. No mutation-positive/ IVCT-negative diagnosis was found. Genetic evaluation of RYR1-mutations can secure a diagnosis and aid in genetic counselling of individual family members but only in those families in which significant clinical information is present, as well as phenotyping by IVCT has been realized.

A survey of obstetric an aesthesia practice in Flanders

The use of locoregional anaesthesia in obstetrics in Flanders was assessed by a postal questionnaire sent to the directors of the anaesthesia departments of the 72 hospitals with an obstetric unit. 59 (82%) answers were returned. In the group of parturients who had a vaginal delivery a neuraxial technique was requested by 65% of the patients and consisted of epidural analgesia in 84%, and combined spinal epidural analgesia in 16%. Test doses are used in labour in 67%. To perform the block--spinal as well as epidural--the sitting position is somewhat preferred over the left lateral (55 versus 45%). For caesarean section general anaesthesia was used in only 5% of the deliveries, whereas spinal, single or as a part of a CSE technique, was preferred in 80%; the epidural technique was applied in 15%. There is no clear preference in technique for postoperative analgesia after caesarean delivery as both parenteral and epidural analgesia are used in 50% of the cases.

Multicentre evaluation of in vitro contracture testing with bolus administration of 4-chloro-m-cresol for diagnosis of malignant hyperthermia susceptibility

BACKGROUND AND OBJECTIVE

The in vitro contracture test with halothane and caffeine is the gold standard for the diagnosis of susceptibility to malignant hyperthermia (MH). However, the sensitivity of the in vitro contracture test is between 97 and 99% and its specificity is 78-94% with the consequence that false-negative as well as false-positive test results are possible. 4-Chloro-m-cresol is potentially a more specific test drug for the in vitro contracture test than halothane or caffeine. This multicentre study was designed to investigate whether an in vitro contracture test with bolus administration of 4-chloro-m-cresol can improve the accuracy of the diagnosis of susceptibility to MH.

METHODS

Three hundred and fifty-two patients from 11 European MH laboratories participated in the study. The patients were first classified as MH susceptible, MH normal or MH equivocal by the in vitro contracture test according to the European MH protocol. Muscle specimens surplus to diagnostic requirements were used in this study (MH susceptible = 103 viable samples; MH equivocal = 51; MH normal = 204). 4-Chloro-m-cresol was added to achieve a concentration of 75 micromol L(-1) in the tissue bath. The in vitro effects on contracture development and muscle twitch were observed for 60 min.

RESULTS

After bolus administration of 4-chloro-m-cresol, 75 micromol L(-1), 99 of 103 MH-susceptible specimens developed marked muscle contractures. In contrast, only two of 204 MH-normal specimens showed an insignificant contracture development following 4-chloro-m-cresol. From these results, a sensitivity rate of 96.1% and a specificity rate of 99.0% can be calculated for the in vitro contracture test with bolus administration of 4-chloro-m-cresol 75 micromol L(-1). Forty-three patients were diagnosed as MH equivocal, but only specimens from 16 patients developed contractures in response to 4-chloro-m-cresol, indicating susceptibility to MH.

CONCLUSIONS

The in vitro contracture test with halothane and caffeine is well standardized in the European and North American test protocols. However, this conventional test method is associated with the risk of false test results. Therefore, an improvement in the diagnosis of MH is needed. Regarding the results from this multicentre study, the use of 4-chloro-m-cresol could increase the reliability of in vitro contracture testing.

Recent advances in the diagnosis of malignant hyperthermia susceptibility: how confident can we be of genetic testing?

Malignant hyperthermia (MH) is a condition that manifests in susceptible individuals only on exposure to certain anaesthetic agents. Although genetically heterogeneous, mutations in the RYR1 gene (19q13.1) are associated with the majority of reported MH cases. Guidelines for the genetic diagnosis for MH susceptibility have recently been introduced by the European MH Group (EMHG). These are designed to supplement the muscle biopsy testing procedure, the in vitro contracture test (IVCT), which has been the only means of patient screening for the last 30 years and which remains the method for definitive diagnosis in suspected probands. Discordance observed in some families between IVCT phenotype and susceptibility locus genotype could limit the confidence in genetic diagnosis. We have therefore assessed the prevalence of 15 RYR1 mutations currently used in the genetic diagnosis of MH in a sample of over 500 unrelated European MH susceptible individuals and have recorded the frequency of RYR1 genotype/IVCT phenotype discordance. RYR1 mutations were detected in up to approximately 30% of families investigated. Phenotype/genotype discordance in a single individual was observed in 10 out of 196 mutation-positive families. In five families a mutation-positive/IVCT-negative individual was observed, and in the other five families a mutation-negative/IVCT-positive individual was observed. These data represent the most comprehensive assessment of RYR1 mutation prevalence and genotype/phenotype correlation analysis and highlight the possible limitations of MH screening methods. The implications for genetic diagnosis are discussed.

Identification of novel mutations in the ryanodine-receptor gene (RYR1) in malignant hyperthermia: genotype-phenotype correlation

Malignant hyperthermia (MH) is a pharmacogenetic disorder of skeletal muscle that is triggered in genetically predisposed individuals by common anesthetics and muscle relaxants. The ryanodine receptor (RYR1) is mutated in a number of MH pedigrees, some members of which also have central core disease (CCD), an inherited myopathy closely associated with MH. Mutation screening of 6 kb of the RYR1 gene has identified four adjacent novel mutations, C6487T, G6488A, G6502A, and C6617T, which result in the amino acid alterations Arg2163Cys, Arg2163His, Val2168Met, and Thr2206Met, respectively. Collectively, these mutations account for 11% of MH cases and identify the gene segment 6400-6700 as a mutation hot spot. Correlation analysis of the in vitro contracture-test data available for pedigrees bearing these and other RYR1 mutations showed an exceptionally good correlation between caffeine threshold and tension values, whereas no correlation was observed between halothane threshold and tension values. This finding has important ramifications for assignment of the MH-susceptible phenotype, in genotyping studies, and indicates that assessment of recombinant individuals on the basis of caffeine response is justified, whereas assessment on the basis of halothane response may be problematic. Interestingly, the data suggest a link between the caffeine threshold and tension values and the MH/CCD phenotype.

Gly341Arg mutation indicating malignant hyperthermia susceptibility: specific cause of chronically elevated serum creatine kinase activity

We report on three families with the Gly341Arg ryanodine receptor gene (RYR1) mutation. Thirteen individuals were heterozygote carriers of the Gly341Arg mutation and had clearly positive in vitro contracture tests, indicating malignant hyperthermia susceptibility. Nine Gly341Arg mutation positive individuals from two families had elevated serum creatine kinase (CK) activity at rest (up to six times the normal upper limit). Their clinical and neurological examinations as well as detailed muscle histology were normal. The third family did not show increased CK activity. These findings indicate that the Gly341Arg mutation can be a specific cause of chronically elevated serum CK activity in asymptomatic individuals.

An image analysis study of vastus lateralis muscle fibers in malignant hyperthermia susceptible patients

We studied the correlation between the in vitro contracture test (IVCT) performed in malignant hyperthermia (MH) and the muscle fiber type composition in 29 human vastus lateralis (VL) biopsy samples (from 12 women and 17 men) using a semiautomated image analyzer. Relative number, lesser diameter, global area, and spatial distribution of the muscle fibers were measured. In these and in 26 additional VL muscle biopsy samples of patients with other myopathies, we compared our morphometric data with the observations made by the pathologist. Among the MH group, type 1 fibers were larger in both malignant hyperthermia susceptible (MHS) men and women reaching statistical significance only in the latter. The relative number and global area were unchanged. In MHS patients relative number and global area of type 2A fibers were smaller. No changes in the parameters of type 2B fibers were found. In a minority of sections (14%) clustering was observed. Sex-related alterations in type 2 fiber characteristics were found between MHS patients. However, our findings do not clearly point towards a syndrome-induced alteration of size, number, global area, or distribution of type 1, 2A, and 2B muscle fibers in VL of MH patients. By morphometric analysis, we found several additional biopsy samples that met the interpretation of "abnormal" size and number of muscle fibers in human malignant hyperthermia than were reported by the pathologist.

Slower recovery of muscle phosphocreatine in malignant hyperthermia-susceptible individuals assessed by 31P-MR spectroscopy

Our aim was to develop an exercise protocol using 31P-magnetic resonance spectroscopy (31P-MRS), which can discriminate between malignant hyperthermia-susceptible (MHS) individuals and controls. MRS spectra of the forearm muscles were recorded at rest, during and after a standardized exercise protocol in 10 MHS patients and compared with spectra obtained in 10 controls. There was no difference in resting intracellular pH (pHi) or PCr/(Pi+PCr) ratio between the groups (PCr = phosphocreatine, Pi = inorganic phosphorus). At the end of the exercise and during the initial recovery phase, the pHi and PCr/(Pi+PCr) ratio were significantly lower in the MHS group ([pHi: 6.37 (0.07) for MHS vs 6.70 (0.05) for controls, P < 0.005; PCr/(Pi+PCr): 0.784 (0.017) for MHS vs 0.954 (0.020) for controls, P < 0.0005]). For PCr/(Pi+PCr), complete separation between the two groups was observed during the initial recovery phase. The mean recovery time of PCr/(Pi+PCr) was 0.57 min for the control group and 1.28 min for the MHS group. The slower recovery of PCr/(Pi+PCr) is likely to be caused by a combination of several factors, including the lower pHi in MHS subjects at the start of recovery (inhibiting ATP production) and excessive sarcoplasmic calcium overload (causing continued enzyme activation and ATP consumption). Our exercise protocol can be a valuable adjunct to discriminate between MHS and non susceptible subjects.

Discordant light microscopic, electron microscopic, and in vitro contracture study findings in a family with central core disease

We report a family that was referred to our laboratory after a fatal malignant hyperthermia (MH) accident during general anesthesia. Postmortem study of different muscles of the proband pointed retrospectively to the presence of central core disease (CCD). Of the 8 family members investigated by histology and in vitro contracture testing (IVCT) 5 were found to be MH-susceptible. Neurological examination was completely normal. Histologically, these 5 patients showed a highly variable proportion (6-89%) of cores in type 1 fibers on light microscopy. In 3 patients definite central cores were found, in 1 patient multicore disease was diagnosed, and 1 patients presented with a mixed central/paracentral form. Electron microscopy could detect cores in only 4 out of 5 patients. These results demonstrate the difficulty to diagnose central or multicore disease and suggest that mixed forms within the same family may occur. The one histologically dubious patient in this family shows that the most sensitive test for the diagnosis of this myopathy might be the IVCT.

In vitro contracture test for diagnosis of malignant hyperthermia following the protocol of the European MH Group: results of testing patients surviving fulminant MH and unrelated low-risk subjects. The European Malignant Hyperthermia Group

BACKGROUND

Determination of sensitivity and specificity of the in vitro contracture test (IVCT) for malignant hyperthermia (MH) susceptibility using the European MH Group (EMHG) protocol has been performed in some laboratories but only on a small sample from the combined EMHG. Thus, the purpose of the present study was to determine combined EMHG sensitivity and specificity of the test.

METHODS

Results of IVCT of patients with previous fulminant MH and normal, low-risk subjects (controls) were collected from 22 centres of the EMHG. IVCT was performed according to the EMHG protocol. Patients were included in the study if the clinical crisis had a score of at least 50 points with the Clinical Grading Scale. Low-risk subjects were included provided they did not belong to a family with known MH susceptibility, they had not developed any signs of MH at previous anaesthetics, and they did not suffer from any neuromuscular disease. For inclusion of both MH patients and low-risk subjects, at least 1 muscle bundle in the IVCT should have twitches of 10 mN (1 g) or more. For evaluation of individual tests, only muscle bundles with twitch heights of 10 mN (1 g) or more were used.

RESULTS

A total of 1502 probands had undergone IVCT because of a previous anaesthesia with symptoms and signs suggestive of MH. Of these, 119 had clinical scores of 50 and above. From these 119 MH-suspected patients and from 202 low-risk subjects, IVCT data were collected. Subsequently, 14 MH-suspected patients were excluded from further analysis for the following reasons: In 3 patients, the suspected MH episode could be fully explained by diseases other than MH; in 11 MHS patients, IVCT was incomplete (n = 1), data were lost (n = 3), or none of the muscle bundles fulfilled twitch criteria (n = 7). Of the remaining 105 MH-suspected patients, 89 were MHS, 10 MHEh, 5 MHEc, and one MHN. Thus, we observed a diagnostic sensitivity of the IVCT of 99.0% if the MHE group is considered susceptible (95% confidence interval 94.8-100.0%). Of the 202 low-risk subjects, 3 were MHS, 5 MHEh, 5 MHEc, and 189 MHN. This gives a specificity of the IVCT of 93.6% (95% confidence interval 89.2-96.5%).

CONCLUSION

The IVCT for diagnosis of MH susceptibility in Europe has a high sensitivity and a satisfactory specificity.

A genome wide search for susceptibility loci in three European malignant hyperthermia pedigrees

Malignant hyperthermia (MH) is an autosomal dominant disorder which is potentially lethal in susceptible individuals on exposure to commonly used inhalational anaesthetics and depolarising muscle relaxants. Crises reflect the consequences of disturbed skeletal muscle calcium homeostasis. Susceptibility was first localised to chromosome 19q13.1 and the skeletal muscle ryanodine receptor, RYR1 (the calcium release channel of the sarcoplasmic reticulum). Defects in this gene have been identified which cosegregate with the MHS phenotype and evidence as to their potential causal roles has accumulated. MH has, however, been shown to be genetically heterogeneous, additional loci on chromosomes 3q, 17q and 7q being proposed. Pedigrees remain in Europe where linkage status is still unclear. In a collaborative search of the human genome conducted with three pedigrees whose disease status was classified according to the European IVCT protocol we have evidence to suggest that at least two further loci exist for MH susceptibility. One of these locates to chromosome 1q, the site of a candidate gene, CACNL1A3, encoding the alpha-subunit of the dihydropyridine receptor. The second region resides on chromosome 5p to where no known candidate has been mapped to date. The third family exhibited inconclusive results which suggests the existence of at least one other locus. This study adds to the evidence for considerable genetic heterogeneity in MH and will provide a route to further our understanding of the molecular pathology of the condition.

Acute poisoning with amphetamines (MDEA) and heroin: antagonistic effects between the two drugs

A case of oral ingestion of large doses of both the amphetamine-derivative 3,4-methylene dioxyethamphetamine (MDEA) and heroin is reported. Despite high serum levels of both drugs, the patient did not present with the classic signs and symptoms normally seen during intoxication with these drugs. The patient recovered after symptomatic treatment. The possibility that opposite pharmacological properties of the two drugs prevented the patients death is discussed.

A 2,4-dichlorophenoxyacetic acid induced fatality

This paper reports on a fatal intoxication by oral ingestion of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D). At admission, the victim was unconscious. His condition deteroriated rapidly with blood loss from his mouth and nose. Since the cause of this condition was not known, gastroscopy was performed and haemorrhagic mucosa was observed in the mouth, oesophagus and stomach. Gastric contents (removed by lavage), urine and blood were submitted for toxicological analysis. Unfortunately, within 3 h of admission (about 5 h following ingestion of the toxin) profound cardiogenic shock developed and the patient died. The identity of the toxic xenobiotic was revealed by gas chromatography-mass spectrometry. Analytical quantification of the herbicide was performed by acid extraction prior to gas chromatographic examination using electron capture detection. His blood level of 2,4-D was 192 mg l-1.

Intracerebral temperature monitoring in severely head injured patients

In a series of 6 severely head injured patients, intraventricular as well as rectal, bladder and jugular vein temperature is recorded. The relationship between these temperatures in different conditions is evaluated. Intracerebral temperature is 0.5 +/- 0.2 degrees C (mean +/- SD) higher than bladder temperature except in conditions such as brain death. It is concluded that rectal temperature is not representative and therefore not a good alternative to the measurement of brain temperature. More data on human intracerebral temperature are mandatory as well as prospective studies correlating intracerebral temperature with final outcome in head injury.

Localization of the gene encoding the alpha 2/delta-subunits of the L-type voltage-dependent calcium channel to chromosome 7q and analysis of the segregation of flanking markers in malignant hyperthermia susceptible families

Malignant hyperthermia susceptibility (MHS) is an autosomal dominant disorder of skeletal muscle which manifests as a potentially fatal hypermetabolic crisis triggered by commonly used anaesthetic agents. The demonstration of genetic heterogeneity in MHS prompted the investigation of the roles played by calcium regulatory proteins other than the ryanodine receptor (RYR1), which is known to be linked to MHS in fewer than half of the European MHS families studied to date. Previously, we have excluded the genes encoding the skeletal muscle L-type voltage-dependent calcium channel alpha 1-, beta 1- and gamma-subunits as candidates for MHS. In this report, we describe the cloning and partial DNA sequence analysis of the gene encoding the alpha 2/delta-subunits, CACNL2A, and its localization on the proximal long arm of chromosome 7q. A new dinucleotide repeat marker close to CACNL2A was identified at the D7S849 locus and tested for linkage in six MHS families. D7S849 and flanking genetic markers were found to co-segregate with the MHS locus through 11 meioses in one, three-generation family. These results suggest that mutations in or near CACNL2A may be involved in some forms of this heterogeneous disorder.

Staged peritoneal lavages with the aid of a Zipper system in the treatment of diffuse peritonitis

A major problem in the surgical treatment of diffuse peritonitis is to obtain a complete clearance of septic foci in the peritoneal cavity which may lead to persistence of sepsis and multiple organ failure. We describe our experience with staged abdominal re-explorations using a Zipper system in 23 patients with a mean APACHE II score of 20.3 (s.e.m: 1.5). A total of 91 lavages were done in these patients. Overall mortality was 39%. None of the patients having an APACHE II score between 10 and 20 died whereas the predicted mortality was 15%-45%. After successful treatment, primary closure was possible in 8 of the 14 surviving patients. Large incisional hernias developed in 6 patients. One patient eviscerated two years after complete granulation of his laparostoma. Staged abdominal re-explorations using a Zipper system is an useful tool in the treatment of diffuse peritonitis.

Detection of a novel common mutation in the ryanodine receptor gene in malignant hyperthermia: implications for diagnosis and heterogeneity studies

Malignant hyperthermia (MH) is a potentially fatal autosomal dominant disorder of skeletal muscle and is triggered in susceptible people by all commonly used inhalational anaesthetics. To date, the ryanodine receptor gene (RYR1) has been shown to be mutated in a small number of malignant hyperthermia susceptible (MHS) cases. To determine if a common RYR1 mutation exists that might account for a significant number of MHS cases, we have investigated the RYR1 gene in unrelated patients for the presence of new mutations by the single-stranded conformation polymorphism method and have identified a novel Gly341Arg mutation which accounts for approximately 10% of Caucasian MHS cases. The implications of this common mutation in MHS diagnosis and heterogeneity studies are discussed.

Genetic mapping of the beta 1- and gamma-subunits of the human skeletal muscle L-type voltage-dependent calcium channel on chromosome 17q and exclusion as candidate genes for malignant hyperthermia susceptibility

Malignant hyperthermia susceptibility (MHS) is an autosomal dominant disorder of skeletal muscle which manifests as a life-threatening hypermetabolic crisis triggered by commonly-used inhalation anaesthetics and depolarizing muscle relaxants. Defects in the ryanodine receptor (RYR1) protein have been proposed to underly MHS, but significant genetic heterogeneity in MHS has recently been demonstrated. In order to investigate the potential roles played by other skeletal muscle calcium channels in MHS, we isolated cosmids containing the gene encoding the beta 1-subunit of skeletal muscle L-type voltage-dependent calcium channel (CACNLB1). We identified a new, highly polymorphic dinucleotide repeat motif close to this gene, and linkage analysis placed the marker proximal to the HOX2B locus, previously localized to chromosome segment 17q21-q22. We recently identified a novel marker within the gamma-subunit locus (CACNLG) at band 17q24, and since both markers are within the 17q11.2-q24 region reported to contain the MHS2 locus, we tested them for linkage in MHS families whose disease trait has been shown not to co-segregate with markers for the RYR1 region on chromosome 19q13.1. Our results exclude CACNLB1 and CACNLG as candidate genes for MHS2, and do not support the reported chromosome 17q localization for the MHS2 locus in our families.

High-resolution physical mapping of four microsatellite repeat markers near the RYR1 locus on chromosome 19q13.1 and apparent exclusion of the MHS locus from this region in two malignant hyperthermia susceptible families

Malignant hyperthermia susceptibility (MHS) is a potentially lethal, hereditary disorder of skeletal muscle that may be triggered by inhalation anesthetics and depolarizing muscle relaxants. Defects in the gene encoding the ryanodine receptor (RYR1) localized on human chromosome 19q13.1 have been proposed to be responsible for MHS. Using a chromosome 19-specific human/hamster somatic cell hybrid mapping panel, we were able to determine that four closely linked microsatellite repeat markers bracket RYR1 with the order 19cen-D19S75-D19S191-RYR1-(D19S47, D19S190)-19ter. Application of the four markers to genetic studies of MHS showed recombination between the markers and MHS in two families, with linkage analysis apparently excluding the MHS locus from the RYR1 region of 19q13.1. These results therefore support the recent observations of genetic heterogeneity in MHS.

In vitro diagnosis of malignant hyperthermia: influence of electrical stimulation on the contracture response to caffeine

We have examined the influence of electrical stimulation on caffeine-induced tension generation during contracture testing used to diagnose malignant hyperthermia. The cumulative contracture response to caffeine was compared in pairs of morphologically comparable muscle bundles obtained from the same patient. Only one of the two bundles was stimulated electrically during the test. Statistically significant differences in tension were found at caffeine concentrations greater than or equal to 4 mmol litre-1, the tension developed being invariably larger in the unstimulated fascicles. These results suggest that electrical stimulation results in suppression of the dose-dependent, caffeine-induced contracture. This effect could be a result of the potentiation of twitch tension by caffeine, muscle fatigue, or both. Overall, the observed differences did not alter the in vitro diagnosis of malignant hyperthermia.

Postpartum dissecting aneurysm of the basilar artery

BACKGROUND AND PURPOSE

Dissecting aneurysms arising from the vertebrobasilar complex are rare and difficult to manage. More of their natural history needs to be known before treatment can be optimized.

CASE DESCRIPTION

We report a postpartum dissecting aneurysm of the right vertebrobasilar artery in a 31-year-old woman that was confirmed by angiographic identification of a double lumen. The intracranial segment of the right vertebral artery was thrombosed proximal to the aneurysm. The patient, managed conservatively, recovered well and, when reexamined 2 months later, was found to be neurologically intact. A repeat angiographic study at that time demonstrated that the aneurysm had resolved.

CONCLUSIONS

Proximal occlusion may have protected the aneurysm from rupture and further dissection, thereby making surgery unnecessary.

In vitro contracture tests in patients with various neuromuscular diseases

In order to investigate the relationship between neuromuscular disease and malignant hyperthermia (MH) susceptibility, the caffeine and halothane in vitro contracture test (European Malignant Hyperthermia Group Protocol) were performed in 60 patients who underwent muscle biopsy for investigation of a clinically suspected neuromuscular disorder. Two test results were classified as MH susceptible, 10 as MH equivocal and 48 MH negative. The large number of equivocal results is thought to indicate the lack of specificity of the individual components of this test in patients with clinical or histological evidence of neuromuscular disease. The increased in vitro sensitivity to the drugs tested may nevertheless provide some explanation for several in vivo "MH-like reactions" reported frequently in these patients. These reactions, however, are likely to be based on pathophysiological mechanisms different from those responsible for a true MH crisis.

The caffeine contracture test for malignant hyperthermia: caffeine citrate, caffeine benzoate or caffeine free base?

The aim of the present study was to investigate whether the three different caffeine preparations--caffeine citrate, caffeine benzoate and the free base--used for in vitro diagnosis of malignant hyperthermia susceptibility--produced the same amount of contracture in rat diaphragm. At equimolar caffeine concentrations, the pure base generated more tension in the rat diaphragm muscle than caffeine benzoate or caffeine citrate. The citrate lowers the pH and the free Ca2+ concentration of the test bath and thus suppresses the caffeine contracture. The benzoate is believed to inhibit the caffeine contracture by its carbonyl group in a way similar to the effect of benzocaine.

Haemodynamic monitoring. Problems, pitfalls and practical solutions

The synthesis of adenosine triphosphate (ATP) depends on the coordinated interaction of oxygen delivery and glucose breakdown in the Krebs cycle. Cellular oxygen depots are non-existent, therefore the peripheral cells are totally dependent on the circulation for sufficient oxygen delivery. Shock is the clinical manifestation of cellular oxygen craving. The commonly measured variables--blood pressure, heart rate, urinary output, cardiac output and systemic vascular resistance--are not sensitive or accurate enough to warn of impending death in acutely ill patients nor are they appropriate for monitoring therapy. Calculated oxygen transport and oxygen consumption parameters provide the best available measures of functional adequacy of both circulation and metabolism. In order to optimise oxygen delivery (DO2), 4 interacting factors must be taken into account: cardiac output, blood haemoglobin content, haemoglobin oxygen saturation and avidity of oxygen binding to haemoglobin. For viscosity reasons, the optimal haemoglobin concentration is in the vicinity of 90 to 100 g/L, but for optimising the oxygen transport 100 to 115 g/L or a haematocrit of 30 to 35% seems better. The p50 (the pO2 at which haemoglobin is 50% saturated) describes the oxygen-haemoglobin dissociation curve; normally its value is +/- 27 mm Hg. It can be influenced by attaining normal body temperature, pH, pCO2 and serum phosphorous levels. In order to obtain an arterial blood saturation (SaO2) of more than 90% with acceptable haemodynamics, the ventilation mode and inspired oxygen fraction (FiO2) must be adapted; care must be taken not to stress the labile circulation with haemodynamic compromising ventilation techniques [e.g. high positive end expiratory pressure (PEEP) levels, inverse-ratio ventilation, etc.]. The factor most amenable to manipulation is the cardiac output, with its 4 determinants--preload, afterload, contractility and heart rate. In daily clinical practice, heart rate should be between 80 and 120 beats/min; small variations are acceptable. Important deviations must be treated by chemically [isoprenaline (isoproterenol)] or electrically (pacing techniques) accelerating the heart, or with the different antiarrhythmic drugs. A wide variety of agents is available to decrease the preload: diuretics [especially furosemide (frusemide)], venodilators like nitroglycerin (glyceryl trinitrate), isosorbide dinitrate (sorbide nitrate) and sodium nitroprusside, ACE inhibitors, phlebotomy, and haemofiltration techniques (peritoneal or haemodialysis, continuous arteriovenous haemofiltration). To increase the preload, volume loading using a rigid protocol ('rule of 7 and 3'), preferably with colloids, or vasopressor agents [norepinephrine (noradrenaline), epinephrine (adrenaline), dopamine] are useful. Arterial vasopressors are needed to improve perfusion pressure of 'critical' (coronary and cerebral) arteries. Afterload can be decreased by arterial vasodilators. Predominantly arterial dilators are hydralazine and clonidine, while sodium nitroprusside, nitroglycerin and isosorbide dinitrate have combined arterial and venous dilating actions.(ABSTRACT TRUNCATED AT 400 WORDS)

Transcranial Doppler sonography in subarachnoid hemorrhage

Ten patients presenting a subarachnoid hemorrhage (SAH) due to rupture of a middle cerebral or an anterior communicating aneurysm are presented. Transcranial Doppler (TCD) values are obtained at different time intervals after SAH. The correlation of TCD values, vasospasm and clinical course is discussed.

Lazarus sign and extensor posturing in a brain-dead patient. Case report

A man was declared brain dead after having sustained a gunshot wound to the head. All clinical criteria for the diagnosis of brain death were met. The electroencephalogram was isoelectric, and four-vessel angiography demonstrated the absence of cerebral blood flow. However, stereotypic spontaneous movements were observed which persisted for several hours. The possible mechanism is discussed and a short review of the literature is given.

Transcranial Doppler sonography

A general review of the physical principles and the applications of transcranial Doppler (TCD) sonography is given. This new non-invasive technique is presented as an important diagnostic tool in neurology, neurosurgery and intensive care medicine. The applications are documented using our own patient material.

Peliosis hepatis associated with liver and retroperitoneal abscesses

A 33-year-old woman was admitted because of coma and severe shock. CT-scan of the abdomen showed the presence of multiple liver abscesses associated with a retroperitoneal abscess which were drained percutaneously. A liver biopsy showed diffuse peliosis. After resolution of the abscesses the patient's general condition improved and she could be discharged from hospital. Peliosis hepatis is an uncommon disorder characterized by dilated sinusoids with formation of blood lakes. Many pathogenetic mechanisms and causal agents have been proposed. Liver biopsy is necessary to establish diagnosis. By withdrawing the offending drug or treatment of the underlying disorder, regression may be observed.

Extradural analgesia during labour using alfentanil

Sixteen primiparous patients requesting pain relief during labour received a continuous infusion of alfentanil 30 micrograms kg-1 h-1 via an extradural catheter. Supplementary (extradural) bolus doses (30 micrograms kg-1) were administered when deemed necessary. Excellent pain relief was rapidly obtained early in labour in all patients. However, analgesia was inadequate in the latter part of stage I and during the second stage in five of the 16 patients--notwithstanding several additional doses of alfentanil, and bupivacaine had to be administered. No serious maternal side-effects, except nausea, were encountered. Although all neonatal Apgar scores were between 7 and 10, the Amiel-Tison test clearly indicated the existence of neonatal hypotonia. The continuous extradural administration of alfentanil proved to be unsatisfactory for pain relief in labour.

Effects of etomidate on ovarian steroidogenesis

The present study investigated the influence of two i.v. induction agents, etomidate (0.25 mg/kg) and thiopental (4 mg/kg) followed by isofluorane anaesthesia on the venous blood concentrations of prolactin (PRL), follicle-stimulating hormone (FSH), 17 beta-oestradiol (E2), progesterone (P), 17OH-progesterone (17OH-P) and testosterone (T) in 18 patients during laparoscopy for oocyte aspiration for in-vitro fertilization. A sharp decrease in the plasma concentration of E2 (P less than 0.01), P (P less than 0.01), 17OH-P (P less than 0.01) and T (P less than 0.01) was observed within 10 min after induction of anaesthesia with etomidate, followed by a gradual return to the baseline levels thereafter. No such decrease was noted after the administration of thiopental. These findings suggest that etomidate, which has previously been reported to inhibit adrenocortical steroidogenesis, can also interfere with the endocrine function of the ovary.

Pharmacokinetics and placental transfer of intravenous and epidural alfentanil in parturient women

Alfentanil was administered as a 30 micrograms/kg single intravenous injection to five healthy women scheduled for elective cesarean section (group A). In five pregnant women normal vaginal delivery was supported by epidural analgesia with a 30 micrograms/kg loading dose followed by a 30 micrograms/kg-1/hr-1 infusion of alfentanil (group B). Five healthy nonpregnant women scheduled for minor general surgery received 120 micrograms/kg alfentanil intravenously as a bolus before surgical incision (group C). In groups A and B plasma alfentanil concentrations, alfentanil plasma protein binding, and alpha 1-acid glycoprotein (alpha 1-AGP) concentrations were measured in maternal and umbilical arterial or venous blood samples at delivery. Multiple arterial sampling in groups A and C for measurement of alfentanil plasma concentration decay analysis indicated three-compartmental characteristics in most patients. In the pregnant population terminal half-life (t1/2 beta), volume of distribution at steady state (Vdss), and total plasma clearance (Clp) amounted to 103 +/- 67 min, 541 +/- 155 ml/kg and 6.48 +/- 0.85 ml/kg-1/min-1, respectively (mean +/- SD), and did not differ significantly in nonpregnant patients. In groups A and B the fetal-maternal ratios indicated a concentration gradient for the total plasma alfentanil content (ratio of total alfentanil concentrations in umbilical venous and maternal blood (Uv/M), 0.31 +/- 0.08 and 0.28 +/- 0.06 (mean +/- SD) in groups A and B respectively) with a larger protein binding capacity in maternal plasma (group A, 85 +/- 3%; group B, 90 +/- 1%) (mean +/- SD).(ABSTRACT TRUNCATED AT 250 WORDS)

Ciramadol as analgesic adjunct to anesthesia in short surgical procedures

The present study was undertaken to assess the intensity and duration of analgesic effect of ciramadol during induction and maintenance of general anesthesia for short surgical procedures. Sixty female patients received either ciramadol 2 mg.kg-1 or saline before anesthesia induction with thiopental-succinylcholine followed by enflurane maintenance. The changes in heart rate following intubation and surgical incision were partially obtunded by ciramadol pretreatment but mean arterial pressure remained significantly elevated till 6 min. post surgical incision. No evidence of impairment of the spontaneous ventilation was observed even when enflurane anesthesia was added. Addition of enflurane also had no deleterious effects on the cardiovascular performance in the ciramadol treatment group. In the absence of pretreatment with ciramadol, the higher concentrations of enflurane needed induced a significantly lower blood pressure but the rise in heart rate observed remained notably larger than in the ciramadol group. This was accompanied by a reduction of spontaneous ventilation as evidenced by the decrease of minute volume. With both techniques end-tidal carbon dioxide tensions rose to the same extent. Maintenance of adequate anesthesia required a larger amount of enflurane in the non-pretreated group. This could indicate an anesthesia sparing effect of ciramadol.

Ciramadol. The therapeutic dose range during balanced anesthesia

In this study we attempted to determine whether ciramadol, a mixed opioid agonist-antagonist, would provide a satisfactory analgesic supplementation to an anesthetic technique for major surgery. Fourteen surgical patients received a balanced anesthesia technique with nitrous oxide, oxygen and muscle relaxants following thiopental induction. Incremental doses of ciramadol were administered as indicated by the somatic, hemodynamic or other sympathetic responses to anesthetic and surgical stimulations. The mean requirements of ciramadol during surgery were inferred from each patient's time-dose curve. The mean loading dose of ciramadol needed was 2.5 +/- 0.4 mg/kg and for maintenance of the analgesic effects, ciramadol had to be administered at a rate of 0.41 +/- 0.09 mg/kg.h. The important transformation rate (50.4%/h) was suggestive of an analgetic ceiling effect. Despite the very large amounts of ciramadol given, the hemodynamic responses to noxious stimuli were not fully suppressed with hypertensive episodes occurring during surgery. Recovery of spontaneous ventilation appeared promptly after completion of surgery and no evidence of respiratory depression was seen. Minute ventilation, respiratory rate and arterial PaCO2 remained within normal limits up to two hours after the end of anesthesia. No incidence of adverse psychotomimetic effects was observed.

Pulmonary edema during cesarean section related to the use of oxytocic drugs

We report the case of an acute pulmonary edema occurring during cesarean section under general anesthesia in a previously healthy negro parturient. This acute event was probably due to the hemodynamic effects of three oxytocic drugs, oxytocin, methylergometrine maleate and prostaglandin F2 alpha used to control severe third-stage bleeding in interaction with the hemodynamic effects of pregnancy at term and surgical and anesthetic stress. The cardiovascular effects of these drugs are reviewed. For a safer conduct of anesthesia, oxytocin for control of uterine bleeding is recommended to be administered by slow intravenous drip and ergometrin by intramuscular injection. The safety of the intramyometrial injection of PGF2 a still remains to be proven.