Noninvasive pressure support ventilation during weaning reduces weaning time, shortens the time in the intensive care unit, decreases the incidence of nosocomial pneumonia, and improves 60-day survival rates.

Background -Non-invasive mechanical ventilation is increasingly used in the treatment of acute respiratory failure in patients with chronic obstructive pulmonary disease (COPD). The Non-invasive mechanical ventilation is increasingly being used in the treatment of acute respiratory failure in patients with chronic obstructive pulmonary disease (COPD). To date, controlled studies comparing non-invasive mechanical ventilation with endotracheal intubation are lacking, so the use of non-invasive mechanical ventilation as an alternative to intubation might, if unsuccessful, unduly delay endotracheal intubation.l The aim of this study was to identify simple measures which could be used to predict whether patients with COPD could be successfully treated with noninvasive mechanical ventilation, and also to avoid unnecessary delay in intubation of those who deteriorate on non-invasive mechanical ventilation. MethodsWe retrospectively reviewed the data of 47 patients with COPD (31 men) undergoing 59 consecutive episodes of acute respiratory failure. All were chronically hypoxaemic and hypercapnic and on long term oxygen therapy. Patients with relevant concomitant diseases were excluded. All had undergone acute relapses of their primary disease and had been given non-invasive mechanical ventilation and met the following criteria: rapid deterioration in neurological status,5 acute onset of severe hypercapnia (Paco2 >8-5 kPa), acute decrease in pH (<7 35), tachypnoea and/or abdominal paradox. The attending physicians considered that all these patients were likely to require mechanical ventilation and performed a short (1-2 hours) trial of non-invasive mechanical ventilation before endotracheal intubation when, according to their own clinical judgement, the clinical and functional status deteriorated despite non-invasive mechanical ventilation.Mechanical ventilation was added to standard medical and oxygen therapy. Modalities of non-invasive mechanical ventilation were either pressure support ventilation (NPSV) (25 episodes) or intermittent positive pressure ventilation (NIPPV) in assisted/controlled mode (34 episodes) delivered through either nasal or facial masks. The ventilatory settings were as previously described.3 The following data were considered from the case records:

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We conclude that in COPD patients, different levels of PSV may induce different respiratory patterns and gas exchange. PS levels capable of obtaining a satisfactory equilibrium in blood gases may result in ineffective respiratory efforts if external PEEP is not applied. The addition of PEEPe, not exceeding dynamic intrinsic PEEP, may also reduce the metabolic work of the diaphragm without altering gas exchange.

Background-Idiopathic pulmonary fibrosis is an inflammatory disease which leads to chronic ventilatory insuYciency and is characterised by a reduction in pulmonary static and dynamic volumes. It has been suggested that lung elastance may also be abnormally increased, particularly in end stage disease, but this has not been systematically tested. The aim of this study was to assess the respiratory mechanics during mechanical ventilation in patients aVected by end stage disease. Methods-Respiratory