The carbon footprint of surgical operations: a systematic review update

INTRODUCTION

Sustainability in healthcare is a rapidly developing area of research with recent formal recognition from institutions around the world. We completed an update of a systematic review published in 2020. The aims of this review were to determine the reported carbon footprints of surgical operations in hospitals worldwide, identify variations in reported carbon footprints and highlight carbon hotspots associated with surgery.

METHODS

A systematic review was conducted in accordance with the PRISMA (Preferred Reporting Items for Systematic reviews and Meta-Analyses) guidelines. The MEDLINE®, Embase® and Cochrane Library databases were searched, and eligibility criteria applied. The study characteristics, scope of product inventory and results were extracted and synthesised. A quality assessment of each study was completed to inform the reliability of the research.

RESULTS

1,308 articles were identified and 7 met the inclusion criteria for the review. The carbon footprint ranged from 28.49kg to 505.1kg carbon dioxide equivalents (CO2e). Medical devices and consumables were the greatest contributor to emissions, with material production and manufacture representing the majority of this carbon hotspot. There were significant methodological limitations and a lack of consistency in carbon footprint calculations between studies.

CONCLUSIONS

This systematic review identifies medical devices and consumables as the largest carbon hotspot where healthcare providers should target their sustainability initiatives. Nevertheless, the number of studies was limited and the quality of the evidence was weak. We recommend that researchers in healthcare sustainability develop international standards for conducting and reporting such studies. This would allow for comparison of individual studies and facilitate meta-analysis of cumulative evidence. A reliable evidence base is a prerequisite for identifying optimal interventions to ensure societal benefits.

The Tulip GT® airway versus the facemask and Guedel airway: a randomised, controlled, cross-over study by Basic Life Support-trained airway providers in anaesthetised patients

We performed a randomised, controlled, cross-over study of lung ventilation by Basic Life Support-trained providers using either the Tulip GT® airway or a facemask with a Guedel airway in 60 anaesthetised patients. Successful ventilation was achieved if the provider produced an end-tidal CO2 > 3.5 kPa and a tidal volume > 250 ml in two of the first three breaths, within 60 sec and within two attempts. Fifty-seven (95%) providers achieved successful ventilation using the Tulip GT compared with 35 (58%) using the facemask (p < 0.0001). Comparing the Tulip GT and facemask, the mean (SD) end-tidal CO2 was 5.0 (0.7) kPa vs 2.5 (1.5) kPa, tidal volume was 494 (175) ml vs 286 (186) ml and peak inspiratory pressure was 18.3 (3.4) cmH2 O vs 13.6 (7) cmH2 O respectively (all p < 0.0001). Forty-seven (78%) users favoured the Tulip GT airway. These results are similar to a previous manikin study using the same protocol, suggesting a close correlation between human and manikin studies for this airway device. We conclude that the Tulip GT should be considered as an adjunct to airway management both within and outside hospitals when ventilation is being undertaken by Basic Life Support-trained airway providers.

[Genetics and prevention of genetic aortic syndromes (GAS) and of the Marfan syndrome]

BACKGROUND

Genetic aortic syndromes are autosomal-dominantly heritable aneurysms of the thoracic aorta, which carry a high risk of aortic rupture or acute thoracic aortic dissection at young age.

OBJECTIVES

We introduce the reader to the principles of genetic diagnostics and the medical and surgical prevention of thoracic aortic dissection in patients with genetic aortic syndromes.

METHODS

A cardiologist, a health economist, a patient representative, a heart surgeon, and a molecular geneticist teamed up to elucidate their perspective on major aspects of genetics and prevention of genetic aortic syndromes.

RESULTS

Genetic aortic syndromes reflect a broad spectrum of diverse disease entities comprising the Marfan syndrome, the Loeys-Dietz syndrome or the vascular Ehlers-Danlos syndrome. The diagnosis of each respective disease entity requires combined assessment of phenotype and genotype information. A medical prevention of aortic complications such as dissection is mandatory although a curative therapy currently appears unlikely in humans. The single most important measure against acute aortic dissection is the preventive replacement of the aortic root, where valve preserving techniques appear preferable. Comprehensive prophylaxis including molecular diagnostics seem reasonable also from an economic point of view.

DISCUSSION

Optimal prevention requires individualization of concepts, which entail a detailed diagnostic characterization of each specific genetic aortic syndrome including characterization of the genotype.

Confirmation of TTC8 as a disease gene for nonsyndromic autosomal recessive retinitis pigmentosa (RP51)

Nonsyndromic retinitis pigmentosa (RP) is genetically highly heterogeneous, with >100 disease genes identified. However, mutations in these genes explain only 60% of all RP cases. Blood samples were collected from 12 members of an autosomal recessive RP family. Whole genome homozygosity mapping and haplotype analysis placed the RP locus in this family at chromosome 14q31.3. Whole-exome sequencing (WES) in proband revealed a mutation in TTC8, which was flagged as most likely candidate gene by bioinformatic analysis. TTC8 is mutated in Bardet-Biedl syndrome 8 (BBS8), and once reported previously in a family with nonsyndromic RP. Sequencing of amplified products of exon 13 of TTC8 validated c.1347G>C (p.Gln449His), a novel change that affects the final nucleotide of exon 13 and might deleteriously affect splicing. This mutation segregated completely with the disease in the family and was not observed in 100 ethnically matched controls from same population. This represents second report of a TTC8 mutation in nonsyndromic RP, thus confirming the identity of TTC8 as causative gene for RP51.

A pilot study to examine the effect of the Tulip oropharyngeal airway on ventilation immediately after mask ventilation following the induction of anaesthesia

The Tulip airway is an adult, disposable, single-sized oropharyngeal airway, that is connectable to an anaesthetic circuit. After a standardised induction of anaesthesia in 75 patients, the ease of insertion, intracuff pressure and intracuff volume were measured, as were the end-tidal carbon dioxide levels, airway pressures and tidal volumes over three breaths. Successful first-time insertion was achieved in 72 patients (96%, CI 88.8-99.2%) and after two attempts in 74 patients (99%, CI 92.8-100%). There was outright failure only in one patient. In 60 patients (80%, CI 72.2-90.4%), the Tulip airway provided a patent airway without additional manoeuvres, but in 14 patients, jaw thrust or head extension was necessary for airway patency. The main need for these adjuncts appeared to be an initial under-inflation of the cuff. These promising results are consistent with recent manikin studies using this device.

An audit of the efficacy of a structured handover tool in obstetric anaesthesia

INTRODUCTION

The SAFE handover tool was developed to reduce critical omissions during handovers in obstetric anaesthesia. It comprises a simple proforma onto which the outgoing team documents patients who fall into one of four anaesthetically relevant categories: Sick patients; At-risk patients (of emergency caesarean section, major haemorrhage or anaesthetic problems); Follow-ups; and Epidurals. We hypothesised that its use would reduce the number of critical omissions at handover.

METHODS

The efficacy of the SAFE handover tool was assessed through several audit cycles in a single maternity unit. The four SAFE categories were considered the gold standard, since they encompassed the consensus opinion of senior obstetric anaesthetists with respect to parturients they most wanted to know about at handover. Against these criteria it was possible to compare the number of cases that should have been handed-over against the number that were actually handed-over.

RESULTS

After implementation of the handover tool, patients were four times more likely to be handed-over than without the use of the tool: an increase from 49% to 79% of relevant cases (P<0.0001, OR 4.1, 95% CI 2.19-7.6). The handover tool was particularly effective at increasing the handover rates of Sick and At-risk parturients, which increased from 21% to 67% (P<0.0001, OR 7.7, 95% CI 2.7-21.7) and 25% to 78% (P<0.01, OR 9.9, 95% CI 1.6-61.6), respectively.

CONCLUSION

The SAFE handover tool significantly increased handover rates of anaesthetically relevant parturients. It is easy to remember and consistent with UK National Health Service Litigation Authority's guidance on risk management in maternity units.

TCR repertoire analysis by next generation sequencing allows complex differential diagnosis of T cell-related pathology

Clonotype analysis is essential for complete characterization of antigen-specific T cells. Moreover, knowledge on clonal identity allows tracking of antigen-specific T cells in whole blood and tissue infiltrates and can provide information on antigenic specificity. Here, we developed a next generation sequencing (NGS)-based platform for the highly quantitative clonotype characterization of T cells and determined requirements for the unbiased characterization of the input material (DNA, RNA, ex vivo derived or cell culture expanded T cells). Thereafter we performed T cell receptor (TCR) repertoire analysis of various specimens in clinical settings including cytomegalovirus (CMV), polyomavirus BK (BKV) reactivation and acute cellular allograft rejection. Our results revealed dynamic nature of virus-specific T cell clonotypes; CMV reactivation was linked to appearance of new highly abundant antigen-specific clonalities. Moreover, analysis of clonotype overlap between BKV-, alloantigen-specific T cell-, kidney allograft- and urine-derived lymphocytes provided hints for the differential diagnosis of allograft dysfunction and enabled appropriate therapy adjustment. We believe that the established approach will provide insights into the regulation of virus-specific/anti-tumor immunity and has high diagnostic potential in the clinical routine.

Comprehensive analysis of dural ectasia in 150 patients with a causative FBN1 mutation

The purpose of this study was to perform a comprehensive study of dural ectasia (DE) related to FBN1 mutations. We performed a database analysis of two German metropolitan regions of 150 patients (68 men, 82 women; mean age 35 ± 16 years). All patients had a FBN1 mutation and underwent dural magnetic resonance imaging. Age was <16 years in 20, 16-25 in 27, 26-35 in 67, and >35 in 36 patients. Prevalence of dural ectasia was 89% with criteria of Oosterhof and Habermann, 83% with Fattori, 78% with Lundby, and 59% with Ahn. DE was less frequent in patients <16 years with Ahn and Fattori. DE related to skeletal manifestations with all criteria, to aortic Z-scores and mitral valve prolapse with criteria of Habermann and Lundby, and to age with criteria of Fattori. The Fattori-grade of DE increased with age, aortic Z-scores, and skeletal score points. There was no consistent relationship of DE with any type of FBN1 mutation. DE is frequent in patients with FBN1 mutations irrespective of age and its severity increases during life. Criteria of Oosterhof and Habermann yielded most consistent diagnostic results. DE relates to skeletal involvement, aortic Z-scores, and mitral valve prolapse.

Two Missense Mutations in the Primary Autosomal Recessive Microcephaly Gene MCPH1 Disrupt the Function of the Highly Conserved N-Terminal BRCT Domain of Microcephalin

Primary microcephaly MCPH1 is an extremely rare autosomal recessive disorder associated with congenital microcephaly, mental retardation and a distinctive cellular phenotype of misregulated chromosome condensation. The MCPH1 gene encodes an 835-amino acid protein, microcephalin, which contains 1 N-terminal and 2 C-terminal BRCT (BRCA1 C-terminus) domains. BRCT domains are predominantly found in proteins involved in cell cycle control and DNA repair. Here we describe 1 novel and 1 previously reported MCPH1 missense mutation, p.Trp75Arg and p.Ser72Leu, respectively, in the N-terminal BRCT domain of microcephalin associated with severe congenital microcephaly. Both residues are entirely conserved in the MCPH1 orthologs of all vertebrate species and Drosophila. Proliferating lymphocytes of the patients with p.Trp75Arg and p.Ser72Leu show the unique cellular MCPH1 phenotype of misregulated chromosome condensation, indicating that these missense alterations disrupt the function of the N-terminal BRCT domain of the protein. Interestingly, both residues are strictly conserved in BRCT domains of BRCA1. ClustalW alignments show that the residue p.Ser72 of microcephalin corresponds to p.Ser1715 of the N-terminal BRCT domain of BRCA1, while the microcephalin residue p.Trp75 is analogous to p.Trp1718 in the N-terminal BRCT and to p.Trp1837 in C-terminal BRCT domains of BRCA1. Missense alterations for all 3 corresponding BRCA1 residues were described and are predicted to be deleterious resulting in the destabilization of the BRCA1 protein. Our data on the 2 MCPH1 missense alterations provide further evidence for the functional significance of these residues in BRCT domains.

A simple clinical model to estimate the probability of Marfan syndrome

BACKGROUND

Marfan syndrome is a heritable connective tissue disease. Definitive diagnosis is complex, and requires sequencing of a large gene, FBN1.

AIM

We aimed to develop a simple model to estimate the pre-test probability of Marfan syndrome.

DESIGN

Prospective cross-sectional study.

METHODS

We applied diagnostic standards for definitive diagnosis or exclusion of Marfan syndrome in 329 consecutive persons. In 208 persons with random assignment to our derivation group, we performed multivariate logistic regression to assess 14 clinical variables for inclusion in a prediction model with derivation of score points from the estimated coefficients. We created cut-offs to classify low, moderate and high probability of Marfan syndrome. For validation, we applied the model to the remaining 121 persons.

RESULTS

We identified seven variables for inclusion in the final model, where we assigned four score points to ectopia lentis, two points to a family history of Marfan syndrome, and one point to previous thoracic aortic surgery, to pectus excavatum, to a wrist and thumb sign, to previous pneumothorax, and to skin striae. In the derivation group 12, 42 and 92% of persons with low (≤1 point), moderate (>1-3.5 points) or high pre-test probability (>3.5 points) had Marfan syndrome, compared to 12, 57 and 91%, respectively, in the validation group. Positive likelihood ratios were 13.96 and 8.54 in the high probability group of the derivation and validation group, respectively.

CONCLUSION

A simple prediction model provides evidence for Marfan syndrome. This model can be used to identify patients who require definitive diagnostic work-up.

Analysis of phenotype and genotype information for the diagnosis of Marfan syndrome

Marfan syndrome is considered a clinical diagnosis. Three diagnostic classifications comprising first, Marfan genotype with a causative FBN1 gene mutation; second, Marfan phenotype with clinical criteria of the original Ghent nosology (Ghent-1); and third, phenotype with clinical criteria of its current revision (Ghent-2) in 300 consecutive persons referred for confirmation or exclusion of Marfan syndrome (150 men, 150 women aged 35 ± 13 years) were used. Sequencing of TGBR1/2 genes was performed in 128 persons without FBN1 mutation. Marfan genotype was present in 140, Ghent-1 phenotype in 139, and Ghent-2 phenotype in 124 of 300 study patients. Marfan syndrome was confirmed in 94 and excluded in 129 persons consistently by all classifications, but classifications were discordant in 77 persons. With combined genotype and phenotype information confirmation of Marfan syndrome was finally achieved in 126 persons by Ghent-1 and in 125 persons by Ghent-2 among 140 persons with Marfan genotype, and exclusion was accomplished in 139 persons by Ghent-1 and in 141 persons by Ghent-2 among 160 persons without Marfan genotype. In total, genotype information changed final diagnoses in 22 persons with Ghent-1, and in 32 persons with Ghent-2. It is concluded that genotype information is essential for diagnosis or exclusion of Marfan syndrome.

Dural ectasia in individuals with Marfan-like features but exclusion of mutations in the genes FBN1, TGFBR1 and TGFBR2

Mutations in the genes FBN1, TGFBR1, and TGFBR2 can result in heritable connective tissue disorders comprising the Marfan syndrome and the Loeys-Dietz syndrome. Dural ectasia is a characteristic manifestation of both syndromes. However, dural ectasia has not yet been investigated in connective tissue disorders that are unrelated to mutations in the FBN1, TGFBR1 or TGFBR2 genes. Here, we assessed dural ectasia in 33 individuals both with typical manifestations of heritable connective tissue disease and in whom mutations in all three genes had been excluded. We identified 19 individuals with dural ectasia (58%), who exhibited major skeletal manifestations of the Marfan syndrome more frequently than the remaining 14 persons without dural ectasia (p = 0.06). Moreover, only persons with dural ectasia fulfilled clinical criteria of the Marfan syndrome (p = 0.01). Conversely, aortic aneurysm (12 patients; p = 0.8), aortic dissection (five patients; p = 0.1), spontaneous dissection of the carotid arteries (five patients; p = 1), and mitral valve prolapse (13 patients; p = 0.4) were similarly frequent irrespective of dural ectasia. We conclude that dural ectasia is a marker for connective tissue disease which coincides with skeletal rather than with cardiovascular manifestations, and which may involve currently uncharacterized pathogenetic mechanisms and syndromes.

Marfan syndrome and the evolving spectrum of heritable thoracic aortic disease: do we need genetics for clinical decisions?

Marfan syndrome (MFS) is a disorder of the connective tissue that is inherited in an autosomal dominant fashion and that is classically caused by mutations in the gene coding for fibrillin-1, FBN1. The high mortality of untreated MFS results almost exclusively from aortic complications such as aortic dissection and rupture. However, more than half of patients with Marfan-like features do not have MFS, but have other diseases including inherited aortic aneurysms and dissections (TAAD). We elucidate the increasing spectrum of syndromes associated with Marfan-like features and discuss the clinical implications of these diseases. We performed a systematic review to tabulate all known inherited diseases and syndromes carrying a risk for thoracic aortic disease. We discuss evidence that different syndromes with different causative genes and mutations have different prognoses and profiles of cardiovascular manifestations. We conclude that future decisions for optimized management of patients with inherited TAAD require a comprehensive clinical and genetic work-up.

The human phenotype ontology

A standardized, controlled vocabulary allows phenotypic information to be described in an unambiguous fashion in medical publications and databases. The Human Phenotype Ontology (HPO) is being developed in an effort to provide such a vocabulary. The use of an ontology to capture phenotypic information allows the use of computational algorithms that exploit semantic similarity between related phenotypic abnormalities to define phenotypic similarity metrics, which can be used to perform database searches for clinical diagnostics or as a basis for incorporating the human phenome into large-scale computational analysis of gene expression patterns and other cellular phenomena associated with human disease. The HPO is freely available at http://www.human-phenotype-ontology.org.

Clinical and mutation-type analysis from an international series of 198 probands with a pathogenic FBN1 exons 24-32 mutation

Mutations in the FBN1 gene cause Marfan syndrome (MFS) and a wide range of overlapping phenotypes. The severe end of the spectrum is represented by neonatal MFS, the vast majority of probands carrying a mutation within exons 24-32. We previously showed that a mutation in exons 24-32 is predictive of a severe cardiovascular phenotype even in non-neonatal cases, and that mutations leading to premature truncation codons are under-represented in this region. To describe patients carrying a mutation in this so-called 'neonatal' region, we studied the clinical and molecular characteristics of 198 probands with a mutation in exons 24-32 from a series of 1013 probands with a FBN1 mutation (20%). When comparing patients with mutations leading to a premature termination codon (PTC) within exons 24-32 to patients with an in-frame mutation within the same region, a significantly higher probability of developing ectopia lentis and mitral insufficiency were found in the second group. Patients with a PTC within exons 24-32 rarely displayed a neonatal or severe MFS presentation. We also found a higher probability of neonatal presentations associated with exon 25 mutations, as well as a higher probability of cardiovascular manifestations. A high phenotypic heterogeneity could be described for recurrent mutations, ranging from neonatal to classical MFS phenotype. In conclusion, even if the exons 24-32 location appears as a major cause of the severity of the phenotype in patients with a mutation in this region, other factors such as the type of mutation or modifier genes might also be relevant.

Contribution of molecular analyses in diagnosing Marfan syndrome and type I fibrillinopathies: an international study of 1009 probands

BACKGROUND

The diagnosis of Marfan syndrome (MFS) is usually initially based on clinical criteria according to the number of major and minor systems affected following international nosology. The number of FBN1 mutation carriers, at risk of aortic complications who would not be properly diagnosed based only on clinical grounds, is of growing importance owing to the increased availability of molecular screening. The aim of the study was to identify patients who should be considered for FBN1 mutation screening.

METHODS

Our international series included 1009 probands with a known FBN1 mutation. Patients were classified as either fulfilling or not fulfilling "clinical" criteria. In patients with unfulfilled "clinical" criteria, we evaluated the percentage of additional patients who became positive for international criteria when the FBN1 mutation was considered. The aortic risk was evaluated and compared in patients fulfilling or not fulfilling the "clinical" international criteria.

RESULTS

Diagnosis of MFS was possible on clinical grounds in 79% of the adults, whereas 90% fulfilled the international criteria when including the FBN1 mutation. Corresponding figures for children were 56% and 85%, respectively. Aortic dilatation occurred later in adults with unfulfilled "clinical criteria" when compared to the Marfan syndrome group (44% vs 73% at 40 years, p<0.001), but the lifelong risk for ascending aortic dissection or surgery was not significantly different in both groups.

CONCLUSIONS

Because of its implications for aortic follow-up, FBN1 molecular analysis is recommended in newly suspected MFS when two systems are involved with at least one major system affected. This is of utmost importance in patients without aortic dilatation and in children.

Effect of mutation type and location on clinical outcome in 1,013 probands with Marfan syndrome or related phenotypes and FBN1 mutations: an international study

Mutations in the fibrillin-1 (FBN1) gene cause Marfan syndrome (MFS) and have been associated with a wide range of overlapping phenotypes. Clinical care is complicated by variable age at onset and the wide range of severity of aortic features. The factors that modulate phenotypical severity, both among and within families, remain to be determined. The availability of international FBN1 mutation Universal Mutation Database (UMD-FBN1) has allowed us to perform the largest collaborative study ever reported, to investigate the correlation between the FBN1 genotype and the nature and severity of the clinical phenotype. A range of qualitative and quantitative clinical parameters (skeletal, cardiovascular, ophthalmologic, skin, pulmonary, and dural) was compared for different classes of mutation (types and locations) in 1,013 probands with a pathogenic FBN1 mutation. A higher probability of ectopia lentis was found for patients with a missense mutation substituting or producing a cysteine, when compared with other missense mutations. Patients with an FBN1 premature termination codon had a more severe skeletal and skin phenotype than did patients with an inframe mutation. Mutations in exons 24-32 were associated with a more severe and complete phenotype, including younger age at diagnosis of type I fibrillinopathy and higher probability of developing ectopia lentis, ascending aortic dilatation, aortic surgery, mitral valve abnormalities, scoliosis, and shorter survival; the majority of these results were replicated even when cases of neonatal MFS were excluded. These correlations, found between different mutation types and clinical manifestations, might be explained by different underlying genetic mechanisms (dominant negative versus haploinsufficiency) and by consideration of the two main physiological functions of fibrillin-1 (structural versus mediator of TGF beta signalling). Exon 24-32 mutations define a high-risk group for cardiac manifestations associated with severe prognosis at all ages.

Okuläre Manifestationen und chirurgische Ergebnisse beim Marfan-Syndrom

AIM

This retrospective study should examine and judge the surgical indications and the therapeutic possibilities as well as their complications in patients with ocular manifestations of Marfan syndrome (MFS) diagnosed according to the criteria of the Ghent nosology.

PATIENTS AND METHODS

The study included 17 patients. Operative indications were increasing subluxation of the lens, retinal detachments and secondary glaucoma. The operative procedure depended on patient age and findings. Eleven MFS patients were operated in both eyes and six MFS patients in one eye.

RESULTS

Stabilization or functional improvement of visual acuity could be achieved in all patients in whom no disorders limiting visual acuity or amblyopia were present preoperatively. In six eyes of five patients, lens insertion was accomplished via a pars plana approach. Lens removal without implantation of an intraocular lens was performed in 16 eyes of 10 patients. Pars plana vitrectomy was accomplished in 12 eyes. Complications were well controlled by pars plana vitrectomy.

CONCLUSIONS

Difficult preoperative situations and postoperative complications are not rare in MFS patients. However, they can be controlled well by means of modern vitreous surgery.

Detection of novel skeletogenesis target genes by comprehensive analysis of a Runx2(-/-) mouse model

Runx2 is an essential factor for skeletogenesis and heterozygous loss causes cleidocranial dysplasia in humans and a corresponding phenotype in the mouse. Homozygous Runx2-deficient mice lack hypertrophic cartilage and bone. We compared the expression profiles of E14.5 wildtype and Runx2(-/-) murine embryonal humeri to identify new transcripts potentially involved in cartilage and bone development. Seventy-one differentially expressed genes were identified by two independent oligonucleotide-microarray hybridizations and quantitative RT-PCR experiments. Gene Ontology analysis demonstrated an enrichment of the differentially regulated genes in annotations to terms such as extracellular, skeletal development, and ossification. In situ hybridization on E15.5 limb sections was performed for all 71 differentially regulated genes. For 54 genes conclusive in situ hybridization results were obtained and all of them showed skeletal expression. Co-expression with Runx2 was demonstrated for 44 genes. While 41 of the 71 differentially expressed genes have a known role in bone and cartilage, we identified 21 known genes that have not yet been implicated in skeletal development and 9 entirely new transcripts. Expression in the developing skeleton was demonstrated for 21 of these genes.

The molecular genetics of Marfan syndrome and related disorders

Marfan syndrome (MFS), a relatively common autosomal dominant hereditary disorder of connective tissue with prominent manifestations in the skeletal, ocular, and cardiovascular systems, is caused by mutations in the gene for fibrillin-1 (FBN1). The leading cause of premature death in untreated individuals with MFS is acute aortic dissection, which often follows a period of progressive dilatation of the ascending aorta. Recent research on the molecular physiology of fibrillin and the pathophysiology of MFS and related disorders has changed our understanding of this disorder by demonstrating changes in growth factor signalling and in matrix-cell interactions. The purpose of this review is to provide a comprehensive overview of recent advances in the molecular biology of fibrillin and fibrillin-rich microfibrils. Mutations in FBN1 and other genes found in MFS and related disorders will be discussed, and novel concepts concerning the complex and multiple mechanisms of the pathogenesis of MFS will be explained.

The molecular pathogenesis of the Marfan syndrome

The Marfan syndrome (MFS) is an autosomal dominant heritable disorder of connective tissue with highly variable clinical manifestations including aortic dilatation and dissection, ectopia lentis, and a range of skeletal anomalies. Mutations in the gene for fibrillin-1 (FBN1) cause MFS and other related disorders of connective tissue collectively termed type-1 fibrillinopathies. Fibrillin-1 is a main component of the 10- to 12-nm extracellular microfibrils that are important for elastogenesis, elasticity, and homeostasis of elastic fibers. Mutations in fibrillin-1 are hypothesized to exert their effects by dominant negative mechanisms, but recent work has also emphasized the potential role of proteases and disturbances in tissue homeostasis in the pathogenesis of the MFS. This article provides an overview of the clinical aspects of the MFS and current thinking on the pathogenesis of this disorder.

Choice of opioid for initiation of combined spinal epidural analgesia in labour--fentanyl or diamorphine

Sixty-two women requesting regional analgesia in labour were allocated to receive a 1.5 ml intrathecal injection as part of a combined spinal-epidural (CSE) analgesic technique. This contained either bupivacaine 2.5 mg plus fentanyl 25 microg (group F) or bupivacaine 2.5 mg plus diamorphine 250 microg (group D). Times of analgesic onset and offset were recorded, motor and proprioceptive assessments made and side-effects noted. Analgesic onset was not significantly different between the groups (group F, 8.0 min; group D, 9.5 min; P = 0.3) but time to first top-up request was significantly longer in the diamorphine group (group F, 73 min; group D, 101 min; P = 0.003). Motor loss, assessed by the modified Bromage score, was statistically but not clinically greater in the fentanyl group (P = 0.01). Maternal hypotension, pruritus, proprioceptive loss, nausea and fetal bradycardia were rare and not severe, and their incidences did not differ between groups. No respiratory depression was observed after CSE. This use of diamorphine was not associated with increased side-effects compared with fentanyl/bupivacaine, and it has a longer duration of action.

Classic, atypically severe and neonatal Marfan syndrome: twelve mutations and genotype-phenotype correlations in FBN1 exons 24-40

Mutations in the gene for fibrillin-1 (FBN1) cause Marfan syndrome, an autosomal dominant disorder of connective tissue with prominent manifestations in the skeletal, ocular, and cardiovascular system. There is a remarkable degree of clinical variability both within and between families with Marfan syndrome as well as in individuals with related disorders of connective tissue caused by FBN1 mutations and collectively termed type-1 fibrillinopathies. The so-called neonatal region in FBN1 exons 24-32 comprises one of the few generally accepted genotype-phenotype correlations described to date. In this work, we report 12 FBN1 mutations identified by temperature-gradient gel electrophoresis screening of exons 24-40 in 127 individuals with Marfan syndrome or related disorders. The data reported here, together with other published reports, document a significant clustering of mutations in exons 24-32. Although all reported mutations associated with neonatal Marfan syndrome and the majority of point mutations associated with atypically severe presentations have been found in exons 24-32, mutations associated with classic Marfan syndrome occur in this region as well. It is not possible to predict whether a given mutation in exons 24-32 will be associated with classic, atypically severe, or neonatal Marfan syndrome.

Differential effect of FBN1 mutations on in vitro proteolysis of recombinant fibrillin-1 fragments

Mutations in the fibrillin-1 gene (FBN1) cause Marfan syndrome (MFS), an autosomal dominant disorder of connective tissue with highly variable clinical manifestations. FBN1 contains 47 epidermal growth factor (EGF)-like modules, 43 of which display a consensus sequence for calcium binding (cbEGF). Calcium binding by cbEGF modules is thought to be essential for the conformation and stability of fibrillin-1. Missense mutations in cbEGF modules are the most common mutations found in MFS and generally affect one of the six highly conserved cysteines or residues of the calcium-binding consensus sequence. We have generated a series of recombinant fibrillin-1 fragments containing six cbEGF modules (cbEGF nos. 15-20) with various mutations at different positions of cbEGF module no. 17, which is known to contain a cryptic cleavage site for trypsin. A mutation affecting a residue of the calcium-binding consensus sequence (K1300E) found in a patient with relatively mild clinical manifestations of classic MFS caused a modest increase in susceptibility to in vitro proteolysis by trypsin, whereas a mutation affecting the sixth cysteine residue of the same cbEGF module (C1320S) reported in a severely affected patient caused a dramatic increase in susceptibility to in vitro proteolysis by trypsin. A mutation at the cryptic cleavage site for trypsin abolished sensitivity of wild-type fragments and fragments containing K1300E to trypsin proteolysis. Whereas the relevance of in vitro proteolysis to the in vivo pathogenesis of MFS remains unclear, our findings demonstrate that individual mutations in cbEGF modules can affect these modules differentially and may suggest an explanation for some genotype-phenotype relationships in MFS.

Urgency of caesarean section: a new classification

A new classification for caesarean section was developed in a two-part study conducted at six hospitals. Initially, 90 anaesthetists and obstetricians graded ten clinical scenarios according to five different classification methods--visual analogue scale; suitable anaesthetic technique; maximum time to delivery; clinical definitions; and a 1-5 rating scale. Clinical definitions was the most consistent and useful, and this method was then applied prospectively to 407 caesarean sections at the same six hospitals. There was close agreement (86%) between anaesthetists and obstetricians for the five-point scale (weighted kappa 0.89), increasing to 90% if two categories were combined (weighted kappa 0.91). We suggest that the resultant four-grade classification system--(i) immediate threat to life of woman or fetus; (ii) maternal or fetal compromise which is not immediately life-threatening; (iii) needing early delivery but no maternal or fetal compromise; (iv) at a time to suit the patient and maternity team--should be adopted by multidisciplinary groups with an interest in maternity data collection.

[Surgical therapy of hemivertebrae scoliosis and kyphosis--a retrospective analysis of 53 cases]

AIM OF THE STUDY

We performed a retrospective analysis of the results of operative treatment of 53 patients with congenital scoliosis (n = 47) or kyphosis (n = 6) due to hemivertebrae.

PATIENTS AND METHODS

The mean age of the patients (31 girls and 22 boys) at the time of the initial examination was 6 +/- 4 years. Surgical treatment was carried out on average at the age of 9 +/- 5 years. Follow-up examinations were carried out up to a mean age of 16 +/- 6 years.

RESULTS

The results of operative treatment depended on the localization of the hemivertebrae and the surgical technique. Progression of scoliosis due to a thoracic hemivertebra was halted, but the scoliosis could not be corrected (Cobb angle at initial examination 37 +/- 17 degrees at follow-up 34 +/- 23 degrees). Scoliosis due to lumbar hemivertebrae was reduced by surgery (Cobb angle at initial examination 36 +/- 14 degrees, at follow-up 21 +/- 15 degrees). Surgery without instrumentation led to worse results than did surgery with instrumentation with thoracic as well as lumbar scoliosis. Combined dorsoventral procedures with resection of the hemivertebra seemed to be superior to spondylodesis without resection of the hemivertebra. Surgical correction of kyphosis associated with dorsal hemivertebrae was performed by means of dorsal or dorsoventral spondylodesis with hemivertebra resection (preoperative kyphosis 70 +/- 34 degrees, at follow-up 44 +/- 25 degrees).

CONCLUSION

Spondylodesis without instrumentation is associated with an unsure prognosis with respect to effects on the progression of the scoliosis, even if it is performed on very young patients. In contrast, spondylodesis with instrumentation can achieve better and longer-lasting corrections of scoliosis even with larger initial curvatures. Scoliosis due to lumbar hemivertebrae is more amenable to surgical correction than thoracic scoliosis due to hemivertebrae.

Cranial subdural haematoma associated with dural puncture in labour

A 23-yr-old primagravida sustained a dural puncture during epidural catheter insertion and developed a headache that settled with oral diclofenac and codydramol. On the third day after delivery, she convulsed twice without warning. As plasma urate was increased, the putative diagnosis of an eclamptic fit was made, and magnesium therapy was started. A contrast CT scan revealed that the cause of the patient's symptoms was a subdural haematoma with raised intracranial pressure. A coincidental arteriovenous malformation was noted. This case emphasises the need to consider the differential diagnoses of post-partum headache. The management of acute intracranial haematoma is described.

Clustering of mutations associated with mild Marfan-like phenotypes in the 3' region of FBN1 suggests a potential genotype-phenotype correlation

Mutations in the gene for fibrillin-1 (FBN1) cause Marfan syndrome, a dominantly inherited disorder of connective tissue that primarily involves the cardiovascular, ocular, and skeletal systems. There is a remarkable degree of variability both within and between families with Marfan syndrome, and FBN1 mutations have also been found in a range of other related connective tissue disorders collectively termed type-1 fibrillinopathies. FBN1 mutations have been found in almost all of the 65 exons of the FBN1 gene and for the most part have been unique to one affected patient or family. Aside from the "hot spots" for the neonatal Marfan syndrome in exons 24-27 and 31-32, genotype-phenotype correlations have been slow to emerge. Here we present the results of temperature-gradient gel electrophoresis analysis of FBN1 exons 59-65. Six mutations were identified, only one of which had been previously reported. Two of the six mutations were found in patients with mild phenotypes. Taken together with other published reports, our results suggest that a sizable subset (ca. 40%) of mutations in this region is associated with mild phenotypes characterized by the lack of significant aortic pathology, compared with about 7% in the rest of the gene. In two cases, mutations affecting analogous positions within one of the 43 cbEGF modules of FBN1 are associated with mild phenotypes when found in one of the 6 C-terminal modules (encoded by exons 59-63), but are associated with classic or severe phenotypes when found in cbEGF modules elsewhere in the gene.

Speed of onset of regional analgesia in labour: a comparison of the epidural and spinal routes

This study compares the speed of onset of effective analgesia in two randomly assigned groups of patients requesting analgesia in labour. Patients in the combined spinal-epidural group (n = 69) were given a subarachnoid injection of 1.5 ml containing bupivacaine 2.5 mg and fentanyl 25 microg for initiation of analgesia. Patients in the epidural group (n = 73) were given an epidural injection of 10 ml containing bupivacaine 12.5 mg and fentanyl 50 microg. Mean (SD) onset times to the first pain-free contraction were 10.0 (5.7) min in the combined spinal-epidural group and 12.1 (6.5) min in the epidural group (p = 0.054). Patients in the combined spinal-epidural group suffered a higher incidence of motor weakness and proprioceptive deficit than those in the epidural group (p = 0.01). The incidence of technique failure and side-effects was similar in the two groups. It is our contention that the statistically nonsignificant difference in onset times does not justify the additional potential for side-effects and the extra cost of the equipment involved in the combined spinal-epidural technique.

The molecular genetics of Marfan syndrome and related microfibrillopathies

Mutations in the gene for fibrillin-1 (FBN1) have been shown to cause Marfan syndrome, an autosomal dominant disorder of connective tissue characterised by pleiotropic manifestations involving primarily the ocular, skeletal, and cardiovascular systems. Fibrillin-1 is a major component of the 10-12 nm microfibrils, which are thought to play a role in tropoelastin deposition and elastic fibre formation in addition to possessing an anchoring function in some tissues. Fibrillin-1 mutations have also been found in patients who do not fulfil clinical criteria for the diagnosis of Marfan syndrome, but have related disorders of connective tissue, such as isolated ectopia lentis, familial aortic aneurysm, and Marfan-like skeletal abnormalities, so that Marfan syndrome may be regarded as one of a range of type 1 fibrillinopathies. There appear to be no particular hot spots since mutations are found throughout the entire fibrillin-1 gene. However, a clustering of mutations associated with the most severe form of Marfan syndrome, neonatal Marfan syndrome, has been noted in a region encompassing exons 24 to 32. The gene for fibrillin-2 (FBN2) is highly homologous to FBN1, and mutations in FBN2 have been shown to cause a phenotypically related disorder termed congenital contractural arachnodactyly. Since mutations in the fibrillin genes are likely to affect the global function of the microfibrils, the term microfibrillopathy may be the most appropriate to designate the spectrum of disease associated with dysfunction of these molecules. The understanding of the global and the molecular functions of the fibrillin containing microfibrils is still incomplete and, correspondingly, no comprehensive theory of the pathogenesis of Marfan syndrome has emerged to date. Many, but not all, fibrillin-1 gene mutations are expected to exert a dominant negative effect, whereby mutant fibrillin monomers impair the global function of the microfibrils. In this paper we review the molecular physiology and pathophysiology of Marfan syndrome and related microfibrillopathies.

Definitions in obstetric anaesthesia: how should we measure anaesthetic workload and what is 'epidural rate'?

Crude delivery rate is used to calculate requirements for consultant anaesthetic sessions in the UK, but this calculation is arbitrary and ignores differences in case-mix between units. The term 'epidural rate' is commonly used to indicate regional anaesthetic activity but has never been defined. We challenge both these concepts and illustrate our argument by applying different definitions of obstetric anaesthetic activity to prospectively collected maternity data from 31 211 deliveries over 5 years in two hospitals. Number of anaesthetic interventions is a more accurate reflection of obstetric anaesthetic activity than number of deliveries, with Northwick Park Hospital having about 200-600 more deliveries per year than Chelsea & Westminster Hospital but about 300-400 fewer anaesthetic interventions per year. 'Epidural rate' varied by up to 30% according to the definition used. We conclude that number of anaesthetic interventions should replace crude number of deliveries as a measure of obstetric anaesthetic activity, and that the term 'regional anaesthesia rate' should replace 'epidural rate'.

Dorsal instrumentation for idiopathic adolescent thoracic scoliosis: rod rotation versus translation

The radiographic and clinical outcomes and complications among two groups of adolescent patients treated for idiopathic thoracic scoliosis with dorsal instrumentation using a unified implantation system (Universal Spinal System) were compared retrospectively. A total of 69 patients were included in the study. In 30 patients an intraoperative correction of the scoliosis was performed by translation and segmental correction (translation group, Helsinki). In 39 patients the correction was achieved according to the Cotrel-Dubousset rod rotation maneuver (rod rotation group, Berlin). The goal of the present study is to investigate whether one of the operative procedures leads to a better correction of idiopathic adolescent thoracic scoliosis than the other. The mean follow-up interval was 30 months, with a minimum of 12 months. There were no significant preoperative differences in age (15+/-2 years in both groups), gender, or type of scoliosis (King types 2, 3, and 4). The preoperative radiographic measurements showed no significant differences between the two groups. In both patient groups, the thoracic primary curve, the lumbar secondary curve and the thoracic apical rotation were improved by the operation. Lumbar apical rotation and the sagittal profile were unchanged in both groups. The thoracic primary curve was corrected from 50 degrees +/-6 degrees to 24 degrees +/-7 degrees in the translation group and from 54 degrees +/-11 degrees to 220 degrees +/-11 degrees in the rod rotation group. The extent of the correction of the thoracic curve was significantly greater in the rod rotation group than in the translation group (59% vs. 52% correction). In contrast, the translation procedure seems to have a more beneficial effect on spinal balance than rod rotation. Neurological complications did not occur. In both patient groups an increase in the non-instrumented lumbar curve was noted, in two cases each. In three patients from the rod rotation group the instrumentation had to be removed due to a late infection with negative microbiological results.

Novel exon skipping mutation in the fibrillin-1 gene: two 'hot spots' for the neonatal Marfan syndrome

The Marfan syndrome is an autosomal dominant heritable disorder of connective tissue that involves principally the skeletal, ocular, and cardiovascular systems. The most severe end of the phenotypic spectrum, the neonatal Marfan syndrome (nMFS), is characterized by pronounced atrioventricular valve dysfunction, and death often occurs within the first year of life due to congestive heart failure. Mutations in the gene coding for fibrillin-1, FBN1, are known to cause Marfan syndrome, and have been identified in almost all exons of FBN1. Here, we describe a novel mutation affecting the invariant + 1 position of the splice donor site in intron 31, associated with skipping of exon 31, in a patient with nMFS. Published reports of nMFS are reviewed and a strict definition for nMFS is suggested. If this definition is used, all nMFS mutations reported to date lie in one of two hot spots, comprising mainly missense mutations in FBN1 exons 24-27 and mutations causing skipping of exon 31 or 32.

Towards effective obstetric anaesthetic audit in the UK

Obstetric audit is multidisciplinary, but maternal mortality data represent the only national obstetric anaesthetic audit currently available in the UK. Maternity and neonatal audit is progressing towards the collection of both numerator and denominator data in order to compare local, regional and national figures. Obstetric anaesthetists as a professional group play a significant role in maternity care and have in the past developed a minimum data set. Such a set now requires revision of items, agreement on definitions and integration with national projects. Since local and regional obstetric anaesthesia data collection systems are available, albeit in various manual or computerized forms, this is an achievable target. A standard maternity and neonatal data set which incorporates obstetric anaesthetic clinical items could offer a qualitative comparison of process variables and outcome, but should be under professional anaesthetic control. In addition, the process may enable professional standards to be defined and tested so that high quality obstetric anaesthetic care can be maintained.

Bipolar clamping improves the sensitivity of mutation detection by temperature gradient gel electrophoresis

Temperature gradient gel electrophoresis (TGGE) is a rapid and sensitive screening method for point mutations and other small DNA alterations. Usually a polymerase chain reaction (PCR)-product of 150 to 500 bp that has been clamped at one end by a psoralen molecule or a "GC-clamp" is tested for abnormal melting characteristics by electrophoresis in a temperature gradient. Under optimal conditions, a heterozygous mutation within the fragment is detected through the presence of three additional bands in the TGGE gel, the mutant homoduplex and two heteroduplex bands. However, the ideal pattern of four sharp bands is not always found due to inconsistencies in melting behavior along the sequence of the DNA fragment under study. Some of these fragments show fuzzy bands that may impede or even prevent the detection of a mutation. Here, we describe a method to overcome this problem by utilizing one psoralen clamp at each end of the PCR product. Using TGGE assays established for exons 16, 17, and 18 of the NF1 gene and for exon 14 of the FBN1 gene as examples, we show that bipolar clamping may transform blurred bands into sharp ones and may visualize mutations that could not be detected by conventional single-sided clamping.

Extradural anaesthesia for caesarean section in a patient with syringomyelia and Chiari type I anomaly

We describe elective Caesarean section performed under extradural anaesthesia in a parturient with symptomatic syringomyelia and coexisting Chiari type I anomaly. Syringomyelia is reviewed and the anaesthetic implications of the condition discussed. Anaesthesia should be directed primarily at avoidance of increased intracranial pressure, which can cause sudden deterioration in these patients.