The effects of nocturnal home mechanical ventilation on daytime blood gas disturbances.

Introduction: In chronic alveolar hypoventilation, previous studies of selected patient groups have shown that nocturnal home mechanical ventilation (HMV) may result in improvements in chronic blood gas disturbances during daytime spontaneous breathing. We wished to examine the effects of this treatment in a large sample of non-selected patients prospectively followed up, in a national multicentric register.

Material: A total of 288 patients from a broad diagnostic spectrum were studied. We looked at the blood gases and vital capacity before the patients elected for initiation of HMV and at the first register-recorded follow-up after 6-24 months.

Results: We found statistically significant improvements in PO(2) and PCO(2) (approximately 1 kPa in both) and in base excess, but no changes in vital capacity or calculated alveolo-arterial gradient. All changes were independent of the observation period and only weakly diagnose-related.

Discussion: Our findings extend those of previous studies, showing a relatively early and apparently stable improvement in blood gases after starting and continuing nocturnal HMV. The equal extent of the improvements in blood gases among all the diagnostic groups including the neurological patients with progressive diseases was unexpected.

Conclusion: In 288 patients starting nocturnal HMV electively we found significant improvements in daytime blood gases after 6-24 months. There were no changes in vital capacity or calculated alveolo-arterial gradient.