Reversal of sleep-induced hypoventilation and chronic respiratory failure by nocturnal negative pressure ventilation in patients with restrictive ventilatory impairment

Effect of non-invasive mechanical ventilation on sleep and nocturnal ventilation in patients with chronic respiratory failure

BACKGROUND

Chronic respiratory failure (CRF) is associated with nocturnal hypoventilation. Due to the interaction of sleep and breathing, sleep quality is reduced during nocturnal hypoventilation. Non-invasive mechanical ventilation (NMV), usually performed overnight, relieves symptoms of hypoventilation and improves daytime blood gas tensions in patients with CRF. The time course of the long term effect of NMV on sleep and breathing during both spontaneous ventilation (withdrawing the intervention) and NMV was investigated in patients with CRF due to thoracic restriction.

METHODS

Fifteen consecutive patients (13 women) of mean (SD) age 57.9 (12.0) years with CRF due to thoracic restriction were included in the study. During the one year observation period four polysomnographic studies were performed: three during spontaneous breathing without NMV-before initiation of NMV (T0) and after withdrawing NMV for one night at six months (T6) and 12 months (T12-)-and the fourth during NMV after 12 months (T12+). Daytime blood gas tensions and lung function were also measured.

RESULTS

Spontaneous ventilation (in terms of mean oxygen saturation) progressively improved (from T0 to T12-) during both REM sleep (24.8%, 95% CI 12.9 to 36.9) and NREM sleep (21.5%, 95% CI 12.4 to 30.6). Sleep quality during spontaneous ventilation also improved in terms of increased total sleep time (26. 8%, 95% CI 11.6 to 42.0) and sleep efficiency (17.5%, 95% CI 5.4 to 29.6) and decreased awakenings (54.0%, 95% CI 70.3 to 37.7). Accordingly, REM and NREM sleep stages 3 and 4 significantly improved. However, the most significant improvements in both nocturnal ventilation and sleep quality were seen during NMV at 12 months.

CONCLUSIONS

After long term NMV both spontaneous ventilation during sleep and sleep quality in patients with CRF due to thoracic restriction showed evidence of progressive improvement compared with baseline after withdrawal of NMV for a single night at six and 12 months. However, the greatest improvements in nocturnal ventilation and sleep were achieved during NMV at 12 months.

Long term non-invasive domiciliary assisted ventilation for respiratory failure following thoracoplasty

BACKGROUND

Ventilatory failure is a well recognised complication of patients who have had a thoracoplasty for tuberculosis, but there are few data regarding the value of long term non-invasive assisted ventilation in this situation.

METHODS

Thirty two patients who had had a thoracoplasty 20-46 years previously and who had developed respiratory failure were treated with nocturnal cuirass assisted ventilation or nasal positive pressure ventilation. Their survival and changes in arterial blood gases, nocturnal oximetry, and pulmonary function tests were assessed.

RESULTS

The actuarial survival rates at one, three, five, and seven years after starting treatment were 91%, 74%, 64%, and 55%, respectively. Only seven of the 13 deaths were directly attributable to chronic respiratory or cardiac failure. The arterial PO2, PCO2, mean nocturnal oxygen saturation, vital capacity, and maximal inspiratory and expiratory pressures had all improved at the time of the initial post-treatment assessment (mean 12 days after starting treatment), but no subsequent improvements were seen after up to 48 months of follow up. Neither survival nor physiological improvements were correlated with the patients' age, the interval since thoracoplasty, or the pretreatment arterial blood gas tensions or results of pulmonary function tests.

CONCLUSIONS

These results show that, even when ventilatory failure has developed, the prognosis with non-invasive assisted ventilation is good and the physiological abnormalities can be partially reversed. Patients who develop respiratory failure after a thoracoplasty should be considered for this type of long term domiciliary treatment.

Pulmonary rehabilitation in chronic respiratory insufficiency. 5. Home mechanical ventilation

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Long-term oxygen therapy in patients with diagnoses other than COPD

Long-term O2 prescription in chronic non-COPD hypoxic lung disease is, at present, based largely on physiological rather than on clinical studies. Controlled long-term studies in this field are difficult to perform. The cooperation of many centers is necessary to obtain a large and homogeneous population as the incidence of these diseases is significantly lower than COPD.