[Hyperventilation syndrome: evaluation of voluntary hypoventilation programs in two rehabilitation centers]. / Syndrome d'hyperventilation.

PURPOSE: The effectiveness of a voluntary hypoventilation technique was assessed in two rehabilitation centers in patients with hyperventilation syndrome. METHODS: In the first center, 55 patients participated in an open program determining themselves the frequency and number of their consultations. In the second center 158 patients participated in a 10-week program that imposed five 60-min sessions. RESULTS: In the first center, the patients participated in 4.8 30-min sessions over a 6.1 week period. Their cardinal complaints had declined by 48% (range 14% to 67% depending on the type of complaint) at the end of the program. In the second center the patients experienced an improvement in their comfort of life (less sleep disorders, fatigability, symptoms of severe hypocapnia), increasingly so with each new session, those having completed the program reaching a 62% improvement. DISCUSSION: Due to the strong correlation observed between the clinical improvement (with a longer interval between acute episodes) and the quality of patient participation the beneficial effect of these voluntary hypoventilation rehabilitation programs cannot be attributed solely to the psychological effect of patient care.

[Respiratory patterns induced by bent posture in COPD patients]. / Stratégie respiratoire induite par la station tronc penché chez des sujets BPCO.

Three body positions were studied in order to determine their influence on the respiratory pattern in 7 subjects with chronic airflow obstruction. The positions were sitting lying back (AR), sitting with the trunk leaning forwards (AP) and standing with the trunk leaning forwards (DP). Compared to sitting lying back, sitting in the forward position favoured diaphragmatic improvement and improved the length/tension relationship of the diaphragmatic fibres and of its mechanical coupling with the thoracic cage; as a result the diaphragm took a more important part in the overall inspiratory effort thus relieving the thoracic inspiratory muscular effort. In relation to AR, the standing, leaning forward (DP) increased the end expiratory level and gave rise to the development of active expiration. This change in the usual respiratory manner enables the diaphragm to benefit on inspiration from the help bought by the restoration of the potential energy stored up in the respiratory system during the course of expiration.

Airway anaesthesia and breathing pattern during exercise in normal subjects and in eucapnic patients with chronic airflow obstruction.

In order to deprive vagal upper and large airway receptors, an aerosol of 4% lidocaine (240 mg) was delivered to eight normal subjects and to eight eucapnic patients with chronic obstructive pulmonary disease (COPD). After this procedure, gag reflex (mechanical irritation of the larynx) and cough reflex tested by an aerosol of 10% citric acid were absent in all subjects. The anaesthesia was tolerated well by all the subjects and did not influence baseline pulmonary function tests. Moreover, during exercise, before and after lidocaine, no significant difference in O2 intake (VO2) or in blood gases (measured in patients only) could be observed. After lidocaine administration, no significant changes were seen in any of the respiratory variables studied in normal subjects or in COPD patients compared to the basal conditions. This could indicate that vagal upper and large airway receptors do not play an important role for the breathing pattern and ventilatory drive during exercise either in normal subjects or eucapnic patients with COPD.

Breathing affects venous return from legs in humans.

It is conventionally believed that venous return to the heart increases during inspiration through the combined effect of the fall in intrathoracic pressure and the squeezing of the splanchnic veins by diaphragm descent. In the present study we have tested the hypothesis that in humans venous return from the legs decreases, rather than increases, during inspiration as a result of the rise in abdominal pressure. Ten normal subjects were examined in recumbent posture during various respiratory maneuvers. Venous return from the legs was monitored using an ultrasonic flow recorder (Doppler effect) placed over the femoral veins. Quiet inspiration was associated with a fall in femoral venous blood flow which, for the 10 subjects, averaged (mean +/- SE) 65 +/- 11% of the end-expiratory value. There was, however, a substantial variability between subjects, which could be largely explained by differences in abdominal pressure swings (delta Pab). In fact when the subjects voluntarily changed their patterns of inspiratory muscle use, the amount of fall in femoral blood flow during inspiration varied in proportion to the diaphragmatic contribution to tidal volume and delta Pab; i.e., flow decreased more as the diaphragm contributed more to inspiration and the rise in Pab was greater. During "pure" diaphragmatic breathing flow always ceased completely, whereas during predominantly rib cage inspiration flow increased rather than decreased. Isovolume belly-in maneuvers and gentle external compression of the abdomen also caused cessation of femoral blood flow, indicating that diaphragmatic contraction is not mandatory for venous return from the legs to be impeded during inspiration.(ABSTRACT TRUNCATED AT 250 WORDS)

Thoracoabdominal motion during chest physiotherapy in patients affected by chronic obstructive lung disease.

In 11 patients suffering from chronic obstructive lung disease, thoracoabdominal movements were monitored with magnetometers during various breathing manoeuvres directed by the chest physiotherapist. The signals derived from the magnetometers and the mouth flow were analysed in order to pick up paradoxical movements of one or the other compartment of the chest wall. In contrast to what was observed during spontaneous breathing, especially abdominodiaphragmatic breathing induced in most of the subjects paradoxical movements. The practical importance of accurate monitoring of thoracoabdominal motion during chest physiotherapy is stressed.

Effect of oxygen on breathing during exercise in patients with chronic obstructive lung disease.

In 10 exercising patients with chronic obstructive lung disease (COLD) we measured ventilation (VE), end-tidal CO2 (PETCO2), mean inspiratory flow (VT/TI), the ratio of inspiratory time to total time for one cycle (TI/TTOT), and occlusion pressure at 0.1 s measured at the mouth (P O.1), when they breathed room air and 100% oxygen. Oxygen breathing increased the maximal work load achieved. Furthermore, at the same exercise load, P O.1, VT/TI, VE, heart rate, respiratory frequency (f) decreased significantly in hyperoxia as compared with normoxia. Thoraco-pulmonary impedance assessed by P 0.1/VE and P 0.1/(VT/TI) ratios showed a slight but significant decrease to the respiratory centre. Thus in exercising patients affected by COLD, hyperoxia not only decreases the chemical afferent drive but also may slightly reduce the afferent mechanical drive to the respiratory centre. The decrease in the thoraco-pulmonary impedance may be explained either by an increase in efficiency of the respiratory muscles and/or a decrease in airway resistance.

Low frequency breathing at rest and during exercise in severe chronic obstructive bronchitis.

The effect of low frequency breathing compared with spontaneous breathing was examined at rest and during exercise (40 watts) in 12 patients suffering from severe chronic obstructive bronchitis. At rest low frequency breathing improved significantly the alveolar ventilation and the tensions of oxygen and carbon dioxide in the arterial blood. There was no significant change in ventilation minute volume. During exercise low frequency breathing significantly decreased ventilation minute volume, and there was no significant improvement in gas exchange. The decrease in ventilation during low frequency breathing at 40 watts compared with spontaneous breathing at the same lung volume was due to expiratory flow limitation. The findings suggest that this technique may impair exercise tolerance in patients with severe chronic obstructive bronchitis.