BackgroundPulmonary first pass filtration of particles marginally exceeding ∼7 µm (the size of a red blood cell) is used routinely in diagnostics, and allows cellular aggregates forming or entering the circulation in the preceding cardiac cycle to lodge safely in pulmonary capillaries/arterioles. Pulmonary arteriovenous malformations compromise capillary bed filtration, and are commonly associated with ischaemic stroke. Cohorts with CT-scan evident malformations associated with the highest contrast echocardiographic shunt grades are known to be at higher stroke risk. Our goal was to identify within this broad grouping, which patients were at higher risk of stroke.Methodology497 consecutive patients with CT-proven pulmonary arteriovenous malformations due to hereditary haemorrhagic telangiectasia were studied. Relationships with radiologically-confirmed clinical ischaemic stroke were examined using logistic regression, receiver operating characteristic analyses, and platelet studies.Principal FindingsSixty-one individuals (12.3%) had acute, non-iatrogenic ischaemic clinical strokes at a median age of 52 (IQR 41–63) years. In crude and age-adjusted logistic regression, stroke risk was associated not with venous thromboemboli or conventional neurovascular risk factors, but with low serum iron (adjusted odds ratio 0.96 [95% confidence intervals 0.92, 1.00]), and more weakly with low oxygen saturations reflecting a larger right-to-left shunt (adjusted OR 0.96 [0.92, 1.01]). For the same pulmonary arteriovenous malformations, the stroke risk would approximately double with serum iron 6 µmol/L compared to mid-normal range (7–27 µmol/L). Platelet studies confirmed overlooked data that iron deficiency is associated with exuberant platelet aggregation to serotonin (5HT), correcting following iron treatment. By MANOVA, adjusting for participant and 5HT, iron or ferritin explained 14% of the variance in log-transformed aggregation-rate (p = 0.039/p = 0.021).SignificanceThese data suggest that patients with compromised pulmonary capillary filtration due to pulmonary arteriovenous malformations are at increased risk of ischaemic stroke if they are iron deficient, and that mechanisms are likely to include enhanced aggregation of circulating platelets.

Postural changes in 258 patients with pulmonary arteriovenous malformations (PAVMs) reviewed between 2005 and 2013 were evaluated prospectively using validated pulse oximetry methods. Of the 257 completing the test, 75 (29%) demonstrated orthodeoxia with an oxygen saturation fall of at least 2% on standing. None described platypnoea (dyspnoea on standing). The heart rate was consistently higher in the erect posture: 74 (29%) had a postural orthostatic tachycardia of ≥20 min . Orthostatic tachycardia was more pronounced in PAVM patients than controls without orthodeoxia (age-adjusted coefficient 5.5 (95% CIs 2.6, 8.4) min −1 , p<0.001). For PAVM patients, the age-adjusted pulse rise was 0.79 min −1 greater for every 1% greater drop in oxygen saturation on standing ( p<0.001). In contrast to the postural orthostatic tachycardia syndrome, in this population, there was a trend for more pronounced orthostatic tachycardia to be associated with better exercise tolerance. To the editorPulmonary arteriovenous malformations (PAVMs) result in hypoxaemia due to right-to-left shunting. 1Recent studies highlight that chronic hypoxaemia in ironreplete patients leads to secondary erythrocytosis which preserves arterial oxygen content (CaO 2 ).2 Both shunt fraction 3 and hypoxaemia severity 4 may increase acutely on standing, a phenomenon ascribed to basally situated PAVMs.3 4 Platypnoeaorthodeoxia (dyspnoea and arterial deoxygenation on standing) has been described, particularly in patients with patent foramen ovale.5 However, platypnoea was not our experience in the PAVM population, suggesting they may be able to compensate for acute falls in CaO 2 . The goal of the study was to quantify orthodeoxia and examine potential compensatory mechanisms to facilitate provision of appropriate information to PAVM patients.The study was ethically approved by the Hammersmith, Queen Charlotte's, Chelsea, and Acton Hospital Research Ethics Committee (LREC 2000/5764). Full methods are presented in the online supplementary data supplement. In all, 258 consecutive patients with CT-proven PAVMs were prospectively and newly recruited (2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013) and evaluated as described. Research letter on 28 April 2019 by guest. Protected by copyright.

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Aims Females of child bearing age are at higher risk of negative appendectomy rate, the accepted overall NAR is up to (20-25%). Presented is our study to examine the real NAR in the female’s cohort aged (15-45 years) in the form of quality improvement project to improve patient’s outcome. Methodology Retrospective study in the form of Full audit cycle over 18 months, the first cycle was conducted over 12 months period, followed by the action plan and reassessment over 6 months. Preoperative clinical, laboratory, radiographic and histopathological data were collected. Results Over the whole audit period 632 cases were analysed, 238 cases were females in the child bearing age included in our cohort. Over the first phase 419 appendectomy cases were performed, among those 156(37%) were females in child bearing age. Overall NAR was 29% and in our females cohort was 43.5%. Over the second cycle, 213 cases performed, out of which 82(38%) cases included in our cohort. Overall NAR reduced to 25% and in our cohort was 37% Conclusions Despite the advances in diagnostic modalities, Females are at significantly higher risk of NAR 37%. Our overall NAR reduced from 29% to 25% compared to the young females cohort, the rate dropped from 43% to 37%. specific consideration and regular auditing of results regards this cohort are highly recommended. Validation of appendicitis scores for risk stratification, Serial examinations and radiological adjuncts are possible solutions to reduce the NAR among this group.