Thorax
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Obstructive sleep apnoea (OSA) is associated with high cardiovascular morbidity and mortality. Randomised controlled trials have shown that, on average, treatment of OSA with continuous positive airway pressure (CPAP) reduces blood pressure (BP) by 3-5 mm Hg, although with considerable variation between individuals. No predictors of the change in BP with CPAP have been convincingly identified. This prospective study aimed to determine predictors of BP change, which might provide an insight into the aetiology of the raised BP seen in untreated OSA. ⋯ Improvement in hypersomnolence and the BMI are independent correlates of the fall in 24 hMBP following CPAP therapy. Markers of initial OSA severity did not predict the fall in 24 hMBP. This suggests that sleep fragmentation and its effects may be more important than hypoxia in the pathogenesis of the hypertension associated with human sleep apnoea.
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Respiratory muscle unloading during exercise could improve locomotor muscle oxygenation by increasing oxygen delivery (higher cardiac output and/or arterial oxygen content) in patients with chronic obstructive pulmonary disease (COPD). ⋯ Respiratory muscle unloading during high-intensity exercise can improve peripheral muscle oxygenation despite unaltered systemic Do(2 )in patients with advanced COPD. These findings might indicate that a fraction of the available cardiac output had been redirected from ventilatory to appendicular muscles as a consequence of respiratory muscle unloading.
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Pulmonary veno-occlusive disease (PVOD) is a disorder which causes progressive pulmonary hypertension, usually presenting with worsening dyspnoea and right heart failure. Pulmonary oedema induced by pulmonary vasodilator therapy to reduce pulmonary arterial pressure has been well described in PVOD, but here we describe a case of PVOD presenting with recurrent episodes of acute non-cardiogenic pulmonary oedema, in the absence of significant pulmonary hypertension. Concern over the risk of precipitating pulmonary oedema led us to use inhaled nitric oxide to predict the safety and efficacy of sildenafil.