[Hypercapnic stimulation and ventilation response in the syndrome of sleep obstructive apnea. Comparison of reinhalation and steady state]. / Estimulación hipercápnica y respuesta ventilatoria en el síndrome de apnea obstructiva del sueño. Comparación de reinhalación y estado-estable.

The objective of this study was to assess ventilatory response to stimulation with CO2 in patients suffering obstructive sleep apnea syndrome (OSAS) but without chronic obstructive pulmonary disease (COPD), by examining differences between hyper- and normocapnic patients and comparing the results obtained with the usual techniques used to stimulate hypercapnia (rebreathing and stable-state). To this end, we studied 15 obese patients, all with an apnea-hypopnea index greater than 10 from a polysomnograph lasting a full night. The following lung function tests were performed: spirometry, air way resistance measures and static lung volumes by plethysmograph and arterial gasometry. We later analyzed ventilatory response by the stable-state method, with increasing CO2 concentrations (from 1 to 9%) and by the rebreathing method. Results from the two methods were similar for all patients: delta VE/delta PCO2 (0.64 +/- 0.35 vs 0.67 +/- 0.48 l/min/mmHg; p = 0.59), delta Vt/delta PCO2 (28.33 +/- 16.23 vs 26.42 +/- 16.94 ml/mmHg; p = 0.9), delta Vt/Ti/delta PCO2 (28.82 +/- 20.9 vs 29.41 +/- 23.78 ml/s/mmHg; p = 0.89) y delta P0.1/delta PCO2 (0.11 +/- 0.07 vs 0.117 +/- 0.05 cmH2O/mmHg; p = 0.58). We compared the results obtained by the two techniques by dividing the sample into two groups of 7 and 8 patients, respectively, depending on whether PaCO2 level before stimulation was higher or lower than 45 mmHg. The hypercapnic patients (group I) were older (61 +/- 3.5 vs 50 +/- 9 years; p = 0.04) but were not different with respect to body mass from the normocapnic patients (group II) (37.59 +/- 6.4 vs 34.56 +/- 4.75 kg/m2; p = 0.33). The results from the two techniques for stimulating hypercapnia were similar within each group, with a statistically significant decrease (p < 0.03) in patients with daytime hypercapnia in delta VE/delta PCO2 delta Vt/delta PCO2, delta Vt/Ti/delta PCO2 and delta P0.1/delta PCO2. We conclude that there are no differences in the results obtained with the rebreathing and stable state techniques. Likewise, ventilatory response to stimulation with CO2 in individuals with OSAS and daytime hypoventilation is less than of normocapnic patients.

[Effects of nasal continuous positive airway pressure on lung function in patients with sleep obstructive apnea syndrome]. / Efectos de la presión positiva continua nasal (CPAPn) sobre la función pulmonar en pacientes con síndrome de apnea obstructiva del sueño (SAOS).

Sixty-one patients with obstructive sleep apnea syndrome (OSAS), 26 of whom also had chronic obstructive pulmonary disease (COPD), received treatment by nasal continuous positive airways pressure (nCPAP). To evaluate the effects of this device on daytime lung function, we analyzed pulmonary function tests before treatment with nCPAP and after a mean follow-up period of 12 months (range: 2-22 months). In patients with both OSAS and COPD, we observed a significant decrease in PaCO2 (p < 0.007), in airways resistance (p < 0.002) and in residual volume (p < 0.01); for these same patients we recorded increases in forced vital capacity (p < 0.04) and maximum inspiratory pressure (p < 0.02). We saw no change in lung function in patients with OSAS only. PaO2 increased after treatment in the 15 patients who were initially hypoxemic (p < 0.001). We conclude that after treatment with nCPAP, the greatest changes in respiratory function occur in patients with both OSAS and COPD, who also experience slight decrease in body weight. These changes may be explained by a decrease in auto-PEEP and weight loss.

[Usefulness of dehumidifiers in the reduction of acari concentrations]. / Utilidad de los dispositivos deshumidificadores en la reducción de la concentración de ácaros.

This study analyzes the role of dehumidifiers in asthma prophylaxis. The efficacy of dehumidifiers in the reduction of Dermatophagoides in the bedrooms of 9 patients with specific allergies was evaluated, along with success in reducing in high concentrations of mite allergens (D. pteronissinus I). Results were compared with those for a control group of 8 patients with the same allergy. In the group in whose homes a dehumidifier was installed, there was a significant reduction in relative humidity in the bedroom (54.84 +/- 4.33% and 45.23 +/- 4.92%; p < 0.05) as well as a significant decreased in concentrations of D. pteronissinus I (2.313 +/- 1.831 to 0.42 +/- 0.44 microgram/g; p < 0.05). This was not the case of patients in the control group (51.15 +/- 7.38% to 60.5 +/- 6.15%; p < 0.05 and 3.28 micrograms/g +/- 4.46 to 4.24 +/- 5.10; p = NS).