Benefits at 1 year of nocturnal intermittent positive pressure ventilation in patients with obesity-hypoventi lation syndrome.

BACKGROUND: Patients with the obesity-hypoventilation syndrome (OHS) benefit from non-invasive ventilatory support. We assessed the long-term physiopathological response to 12-months of nocturnal ventilatory assistance at home with bi-level positive airway pressure (BiPAP) via nasal mask in patients with this disease. METHODS: A series of 13 non-consecutive patients diagnosed of OHS (5 men and 8 women) with a mean (SD) age of 61.9 (8) years, underwent the following studies before (baseline) and after 12 months of non-invasive domiciliary mechanical ventilation: arterial blood gases, nocturnal digital pulse oximetry, spirometry, body plethysmography, maximum muscular respiratory pressures and ventilatory pattern with measurement of occlusion pressure (P0.1) before and after hypercapnia. An overnight cardiorespiratory polygraphy was done at baseline. RESULTS: After 12 months of non-invasive mechanical ventilation, there were significant (P < 0.05) reductions of arterial carbon dioxide tension (PaCO2) and increases in arterial oxygen tension, forced vital capacity and ventilatory response to hypercapnia, as measured by the relationship between changes of P0.1 and PaCO2 (deltaP0.1 / deltaPaCO2) as well as respiratory minute volume (V(E)) and PaCO2 (deltaV(E) / deltaPaCO2). Changes of the PaCO2 correlated significantly with those in the (deltaP0.1 / deltaPaCO2) slope (r = 0.576, P < 0.05). CONCLUSIONS: The present results confirm that non-invasive home mechanical ventilation is an effective approach for long-term treatment of OHS.

Abnormalities of the respiratory function and control of ventilation in patients with anorexia nervosa.

BACKGROUND: Anorexia nervosa is a good model to study the effects of malnutrition on the respiratory system, since it excludes the consequences that some chronic diseases can have on the lung. OBJECTIVE: The objective of this study was to assess pulmonary function and alterations in the respiratory system in patients with anorexia nervosa. METHODS: Twenty-two women, 12 with anorexia nervosa and 10 healthy volunteers, were studied. Anthropometric data were gathered for all the participants. In every case, an arterial blood gas test and functional respiratory study, that included spirometry, plethysmography, measure of maximum muscular respiratory pressure and study of the ventilatory pattern at baseline and after hypercapnic stimulation, were performed. RESULTS: No significant differences were found in mean age and height in both groups of patients but there was a difference in body mass index (p < 0.05). In pulmonary function tests, an increase in residual volume (RV), RV/total lung capacity (TLC) ratio and functional residual capacity and a decrease in maximum respiratory pressure were found in patients with anorexia nervosa compared to the control group (p < 0.05). Differences were also found in the ventilatory pattern, with a reduction in minute ventilation and occlusion pressure as well as a decreased response of these parameters to hypercapnic stimulation (p < 0.05) in the patients with anorexia nervosa. CONCLUSION: In patients with anorexia nervosa, a significant elevation in RV, in the RV/TLC ratio and in functional residual capacity and a decrease in the maximum respiratory pressure were noted. In addition, they present an alteration in the central respiratory drive and a response of the respiratory system to hypercapnic stimulation. Although these alterations have no repercussion on the maintenance of gas exchange in baseline conditions, they may have in extreme situations.

[Analysis of withdrawal from noninvasive mechanical ventilation in patients with obesity-hypoventilation syndrome. Medium term results]. / Análisis de la retirada de la ventilación mecánica no invasiva en pacientes con síndrome de hipoventilación-obesidad. Resultados a medio plazo.

OBJECTIVE: To evaluate the possibility of cessation of noninvasive mechanical ventilation or noninvasive positive pressure ventilation (NPPV) treatment in patients with obesity-hypoventilation syndrome (OHS). MATERIAL AND METHODS: A study was carried out on 22 OHS patients who had received NPPV for a minimum of 1 year. Prior to evaluation of the cessation of ventilatory support, all patients underwent the following tests: diurnal and nocturnal arterial blood gases, nocturnal oximetry, nocturnal cardiorespiratory polygraphy, and lung function tests. Based on the results obtained, 12 patients who met the NPPV cessation criteria were selected. This group was liberated from ventilatory support for 3 months. At the end of this period, all of the tests initially carried out were repeated on all patients and the results were compared with those obtained at the time of NPPV cessation. RESULTS: Three months after liberation from NPPV, no significant variations were observed in arterial blood gases or in lung function tests in comparison with the values found at the time of cessation. In terms of individual development, only 1 patient showed blood gas deterioration requiring a return to NPPV. In 7 cases, a polygraph showed obstructive sleep apnea syndrome (OSAS), 4 at the time of cessation and 3 at the follow-up examination carried out at the end of the 3 months. Finally, in 4 patients the respiratory situation remained stable, with no significant variations in the tests done before or after cessation of NPPV. CONCLUSIONS: The majority of the OHS patients who receive prolonged treatment with NPPV continue to be stable 3 months after liberation from ventilatory support. A high percentage of these patients can be seen to have OSAS once the hypercapnia situation is corrected.