Thromboelastometry and Platelet Function during Acclimatization to High Altitude.

Interaction between hypoxia and coagulation is important given the increased risk of thrombotic diseases in chronically hypoxic patients who reside at sea level and in residents at high altitude. Hypoxia alters the proteome of platelets favouring a prothrombotic phenotype, but studies of activation and consumption of specific coagulation factors in hypoxic humans have yielded conflicting results. We tested blood from 63 healthy lowland volunteers acclimatizing to high altitude (5,200 m) using thromboelastometry and assays of platelet function to examine the effects of hypoxia on haemostasis. Using data from two separate cohorts of patients following identical ascent profiles, we detected a significant delay in clot formation, but increased clot strength by day 7 at 5,200 m. The latter finding may be accounted for by the significant rise in platelet count and fibrinogen concentration that occurred during acclimatization. Platelet function assays revealed evidence of platelet hyper-reactivity, with shortened PFA-100 closure times and increased platelet aggregation in response to adenosine diphosphate. Post-expedition results were consistent with the normalization of coagulation following descent to sea level. These robust findings indicate that hypoxia increases platelet reactivity and, with the exception of the paradoxical delay in thromboelastometry clotting time, suggest a prothrombotic phenotype at altitude. Further work to elucidate the mechanism of platelet activation in hypoxia will be important and could impact upon the management of patients with acute or chronic hypoxic respiratory diseases who are at risk of thrombotic events.

Plain film measurement error in acute displaced midshaft clavicle fractures.

BACKGROUND: Clavicle fractures are common and optimal treatment remains controversial. Recent literature suggests operative fixation of acute displaced mid-shaft clavicle fractures (DMCFs) shortened more than 2 cm improves outcomes. We aimed to identify correlation between plain film and computed tomography (CT) measurement of displacement and the inter- and intraobserver reliability of repeated radiographic measurements. METHODS: We obtained radiographs and CT scans of patients with acute DMCFs. Three orthopedic staff and 3 residents measured radiographic displacement at time zero and 2 weeks later. The CT measurements identified absolute shortening in 3 dimensions (by subtracting the length of the fractured from the intact clavicle). We then compared shortening measured on radiographs and shortening measured in 3 dimensions on CT. Interobserver and intraobserver reliability were calculated. RESULTS: We reviewed the fractures of 22 patients. Bland-Altman repeatability coefficient calculations indicated that radiograph and CT measurements of shortening could not be correlated owing to an unacceptable amount of measurement error (6 cm). Interobserver reliability for plain radiograph measurements was excellent (Cronbach α = 0.90). Likewise, intraobserver reliabilities for plain radiograph measurements as calculated with paired t tests indicated excellent correlation (p > 0.05 in all but 1 observer [p = 0.04]). CONCLUSION: To establish shortening as an indication for DMCF fixation, reliable measurement tools are required. The low correlation between plain film and CT measurements we observed suggests further research is necessary to establish what imaging modality reliably predicts shortening. Our results indicate weak correlation between radiograph and CT measurement of acute DMCF shortening.

CONTEXTE: Les fractures de la clavicule sont fréquentes, et le choix du traitement optimal ne fait pas l'unanimité. Selon la littérature récente, la fixation chirurgicale des fractures du tiers médial déplacées (FTMD) aiguës raccourcies de plus de 2 cm donnerait de meilleurs résultats. Nous avons voulu établir une corrélation entre la mesure du déplacement obtenue par radiographie simple et par tomodensitométrie (TDM) et la fiabilité inter- et intra-observateur des mesures radiographiques répétées. MÉTHODES: Nous avons obtenu les radiographies et les TDM de patients ayant subi une FTMD aiguë. Trois orthopédistes et 3 résidents ont mesuré le déplacement radiographique au temps zéro et 2 semaines plus tard. Les mesures par TDM ont permis d'identifier un raccourcissement absolu en 3 dimensions (en soustrayant de la longueur de la clavicule intacte celle de la clavicule brisée). Nous avons ensuite comparé le raccourcissement mesuré par radiographie au raccourcissement en 3 dimensions mesuré par TDM. La fiabilité inter- et intra-observateur a ensuite été calculée. RÉSULTATS: Nous avons ainsi analysé les fractures de 22 patients. Les calculs du coefficient de répétabilité de Bland et Altman ont indiqué qu'il était impossible d'établir des corrélations entre les mesures obtenues par radiographie et par TDM compte tenu de l'ampleur inacceptable de l'erreur de mesure (6 cm). La fiabilité inter-observateur a été excellente pour les mesures radiographiques (coefficient α de Cronbach = 0,90). De même, la fiabilité intra-observateur pour les mesures radiographiques calculée par test t pour échantillons appariés a indiqué une excellente corrélation (p > 0,05 chez tous les observateurs, sauf 1 [p = 0,04]). CONCLUSION: Pour que le raccourcissement devienne une indication de la FTMD, il faut disposer d'outils de mesure fiables. La faible corrélation que nous avons observée entre les mesures obtenues par radiographie et par TDM montre qu'il faut approfondir la recherche afin de déterminer quelle modalité permet de prédire de manière fiable le raccourcissement. Nos résultats démontrent une faible corrélation entre les mesures du raccourcissement obtenues par radiographie et par TDM dans la FTMD aiguë.

Radiographic evaluation of the ankle syndesmosis.

BACKGROUND: Radiographic measurements to document ankle anatomy have been suggested in recent literature to be inadequate. Focus has been put on stress views and computed tomography; however, there are also issues with these modalities. An orthogonal view that could be used both statically and dynamically could help determine syndesmotic stability. The purpose of this study was to determine a parameter on a normal lateral ankle radiograph that will increase the reliability of standard radiography in diagnosing syndesmotic integrity. METHODS: Three orthopedic surgeons reviewed 80 lateral ankle radiographs. Thirty of those radiographs were reviewed on a second occasion. Rotation of the radiographs was determined by evaluating the overlap of the talar dome. Four radiographic parameters were measured 1 cm above the tibial plafond: fibular width, tibial width, and anterior and posterior tibiofibular intervals. RESULTS: Seventy-two radiographs were determined by consensus to be adequate. Means and ratios were documented to determine the relationship of the fibula to the tibia. Interrater reliability ranged from moderate to near-perfect, and the intrarater reliability was documented for each ratio. The anterior tibiofibular ratio was shown to be strong to near-perfect. It demonstrates that 40% of the tibia should be seen anterior to the fibula at 1cm above the tibial plafond. CONCLUSION: The anterior tibiofibular ratio provides an orthogonal measure for the syndesmosis that, in conjunction with those parameters previously documented, could clinically and economically improve the diagnosis of syndesmotic disruptions.

CONTEXTE: Selon la littérature récente, les mesures radiographiques utilisées pour documenter l'anatomie de la cheville seraient inadéquates. L'accent a été placé sur les clichés de cheville en position de stress et sur la tomodensitométrie, mais ces modalités présentent également des inconvénients. Une vue orthogonale utilisée en position statique et en position dynamique pourrait aider à évaluer la stabilité syndesmotique. Le but de cette étude était de déterminer quel paramètre de la radiographie latérale normale de la cheville accroîtrait la fiabilité de la radiographie standard pour le diagnostic de l'intégrité syndesmotique. MÉTHODES: Trois chirurgiens orthopédistes ont passé en revue 80 radiographies latérales de la cheville. Trente de ces radiographies ont été interprétées une deuxième fois. La rotation des radiographies a été déterminée par l'évaluation du chevauchement du dôme talien. Quatre paramètres radiographiques ont été mesurés à 1 cm audessus du plafond tibial : la largeur du péroné, la largeur du tibia et les intervalles tibiofibulaires antérieur et postérieur. RÉSULTATS: Soixante-douze radiographies ont consensuellement été jugées adéquates. Les moyennes et les ratios ont été notés pour établir le rapport péroné-tibia. La fiabilité inter-examinateur a varié de modérée à quasi-parfaite et la fiabilité intra-examinateur a été documentée pour chaque ratio. Le ratio tibiofibulaire antérieur s'est révélé être un paramètre solide à quasi-parfait. Il démontre que 40 % du tibia devrait être visible à l'avant du péroné à 1 cm au-dessus du plafond tibial. CONCLUSION: Le ratio tibiofibulaire antérieur constitue une mesure orthogonale pour la syndesmose qui, en conjonction avec les paramètres précédemment documentés, permettrait d'améliorer le diagnostic des troubles syndesmotiques aux plans clinique et économique.

Contemporary outcomes of open repair of thoracoabdominal aortic aneurysm in young patients.

BACKGROUND: Endovascular technology now permits total endovascular thoracoabdominal aortic aneurysm (TAAA) repair with high volume centres reporting encouraging results. The long-term durability of such stent grafts is unknown, leading to concerns regarding their use in younger patients. This study reports contemporary outcomes of open repair in young patients. METHODS: Outcomes for patients age 60 or younger undergoing open TAAA repair between June 1999 and August 2013 with prospective collected data were analysed retrospectively. RESULTS: Thirty-seven patients (31 men, 84%) with a median age of 56 (range 22-60) were identified with a median TAAA diameter of 6.9 cm (range 5.6-11). Aneurysm aetiology included degenerative change (18), dilation of chronic dissection (10), connective tissue disease (7) and mycotic degeneration (2). Crawford Type IV TAAA were most commonly treated (17), followed by Type II (10), Type III (7) and Type I (3). Two (5%) patients died in hospital, one from multiple organ failure and one from respiratory failure. Three patients (8%) developed temporary paraplegia, all of whom made a complete recovery and 4 (11%) patients required temporary renal replacement therapy. Median critical care stay was 5 days (range 2-28) with an in-hospital stay of 14 days (range 7-83). During a median follow-up of 72 months (range 13-171), no patient subsequently required any further aneurysm related surgical or radiological intervention. The mean (SEM) survival time was 138.5 (11) months. The 5 year survival was 79.7% (8.3) including early deaths, with no aneurysm related complications. CONCLUSIONS: The outcome of open TAAA repair in patients aged less than 60 years is favorable. It is against these results that evolving endovascular interventions must be compared.

Radical surgical debridement alone for treatment of carpal tunnel syndrome caused by mycobacterium avium complex flexor tenosynovitis: case report.

We present a case of proliferative flexor tenosynovitis caused by Mycobacterium avium complex resulting in recurrent symptoms of median nerve compression. The patient was treated with radical tenosynovectomy and release of the carpal tunnel without antimicrobial therapy. She remains symptom-free and is apparently disease-free more than 2 years after surgery.