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Controversy around long term oxygen in COPD
Long term oxygen therapy in COPD with significant hypoxia is well known to improve mortality. However, this randomised, non-blinded trial (NEJM 2016;375:1617–27) comparing long term oxygen therapy in COPD patients with moderate desaturation at rest (89–93%) to a non-masked matched group, published in the NEJM requires careful interpretation. The primary outcome (changed part way through the trial) was time to death or first hospitalisation. Only 738 patients were recruited with 368 assigned to the supplemental oxygen group and 370 to the control group. No significant difference was found between the two groups in mortality or time to hospitalisation, perhaps unsurprising given the nature of the intervention. Secondary endpoints, (arguably underpowered) including time to first exacerbation, rate of hospitalisation or quality of life also showed no statistically significant difference between the two groups. The authors conclude their study is consistent with previous smaller studies that also demonstrated no benefit of long term oxygen therapy in COPD with moderate desaturation. It is unlikely that this trial will impact on clinical practice in the UK because of low usage of oxygen in mild COPD in the UK population.
Human soluble thrombomodulin and idiopathic pulmonary fibrosis
Recombinant human soluble thrombomodulin (rhTM) has been used in the treatment of acute respiratory distress syndrome with some positive outcomes reported. Acute exacerbations of pulmonary fibrosis have a high mortality with no established efficacious treatment. This study (Hayakawa et al. Multidisc Respir Med 2016;11:38) used a combination of rhTM and steroid pulse therapy for 7 days. 10 subjects were included. Study data was compared to a historical group of 13 patients. Mean Pa02/FiO2 (P/F) ratio was the primary outcome with 28 day mortality a secondary endpoint. The rhTM treatment did show a significant improvement in P/F ratio at day 8 compared to day 1, however it did not show a significance difference to the control group. 28 day survival was 70% in the treatment group compared to 50% in the control group however study size did not allow for statistical significance. The study concludes that the treatment may be effective in the treatment of acute exacerbation of idiopathic pulmonary fibrosis although a larger randomised and blinded trial is needed.
CT angiography and pulmonary hypertension
This study (Veld et al. Int J Cardiol 2016:223:723–8) compared the left to right atrial size ratio in patients with pulmonary hypertension secondary to heart failure with preserved ejection fraction (PH-HFpEF) and idiopathic pulmonary hypertension (IPAH). Routine non gated CT angiography of 95 consecutive treatment naïve patients with later confirmed IPAH (64 patients) and PH-HFpEF (31 patients) were compared. On a transversal view LA size was 19 cm2 (±5) in the IPAH group vs 27 cm2 (±6) in the PH-HFpEF group (p<0.001). CT angiography derived left atrial/right atrial (LA/RA) ratio was significantly higher in the PH-HEpEF group. Assessing LA/RA ratio by non gated CT angiography allowed for accurate discrimination between IPAH and PH secondary to left heart disease. The authors feel this may allow a subset of patients to avoid further invasive haemodynamic measurements.
PE in patients hospitalised from syncope
PE is an established cause of syncope but its prevalence in this group of patients is unclear. Current guidelines on syncope also pay little attention to a diagnostic work up to exclude PE. This cross sectional study (Prandoni et al. NEJM 2016;375:1524–31) sought to assess the prevalence of PE in hospitalised patients with syncope. Consecutive patients admitted over a 2 year period were recruited. Patients who were not admitted to hospital or who were already on anticoagulant therapy were excluded. 560 patients were included in the study. In 330 patients (58.9%) a diagnosis of PE was excluded based on a low pretest probability (based on wells score) and a negative d dimer. The remaining patients (high wells score, positive d dimer or both) included 230 patients. PE was identified in 97 (42.2%) of this group, a rate of 17.3% of all patients admitted with a first episode of syncope. Over half had a clot burden in a main or lobar artery. The prevalence rate is higher than previously reported and the authors acknowledge the need for further investigation to establish the significance of smaller PEs.
Footnotes
Competing interests None declared.
Provenance and peer review Commissioned; internally peer reviewed.