Alteration of Swallowing and Ventilation Coordination in Respiratory Diseases in Small Mammals.

In human and animal, swallowing and ventilation are coordinated to avoid laryngeal penetration or tracheal aspiration, and respiration is interrupted during swallowing and resumes in the expiratory phase. Some respiratory diseases may alter this coordination due to impaired lung function. The aim of this study was to evaluate swallowing-ventilation coordination in unrestrained rats with pulmonary emphysema or with pulmonary fibrosis. Two protocols were performed in 38 male Sprague-Dawley rats (2-3 months, 250-300 g): pulmonary emphysema and pulmonary fibrosis. Ventilation during swallowing and swallowing-ventilation coordination were recorded using a whole-body plethysmography and video recordings. The rats were free to take water after 24 h without drinking. Compared to control groups, swallowing frequency was significantly higher in rats with pulmonary emphysema and there was a decrease of swallows during expiration in rats with pulmonary emphysema and in rats with pulmonary fibrosis. In this study, we show that respiratory diseases are associated with changes in swallowing-ventilation coordination and hypothesize that they increase the risk of aspiration.

Effect of liquid properties on swallowing and ventilation coordination in rats.

BACKGROUND: One aspect of rehabilitation in swallowing disorders is to change liquid properties. The objective of our study was to test how liquid properties could improve oropharyngeal dysphagia and swallowing and ventilation coordination in an animal model. METHODS: Forty-two healthy male rats were distributed in six groups, including a control group. Rats were deprived of water for 24 h and then each group was administered liquid with different properties: tap water, sugar water, sparkling water, salt water, cold water, and acidic water. Rats were studied without and with oropharyngeal dysphagia achieved by unilateral section of the hypoglossal nerve. Swallowing and ventilation were analyzed by barometric plethysmograph. KEY RESULTS: In healthy rats, swallowing occurred during expiratory time for all liquid properties. Most deglutitions were during expiratory time for all liquid properties (88±12%) and were not modified. There was an increase in VT/TI during swallowing with sparkling water and cold water (P<.05). In the operated groups, rats had significantly fewer swallows with tap water (P<.05) and significantly more swallows with sparkling water (P<.001), sugar water (P<.001) and cold water (P<.001) during expiratory time. The mean inspiratory volume (VT/TI) increased with sparkling water (P<.05). CONCLUSION AND INFERENCES: Sparkling water seemed to improve swallowing and ventilation coordination in an animal model, to be confirmed in a study including patients with oropharyngeal dysphagia.

[The importance of lung volumes in the investigation of heavy smokers]. / Place de la distension pulmonaire dans l'exploration des gros fumeurs de cigarettes.

INTRODUCTION: Lung hyperinflation (LH) has become a major concern in the management of chronic obstructive pulmonary disease (COPD). MAIN AIM: To evaluate the role of lung volumes in the positive diagnosis of COPD and in the assessment of airway obstruction reversibility. POPULATION AND METHODS: Three hundred and sixty-six male smokers over the age of 35 with more than 40 pack-years exposure were included in the study. Plethysmographic data were determined before/after taking a bronchodilator (BBD, ABD). Applied definitions: airflow obstruction: BBD FEV1/FVC<0.70. LH: BBD residual volume (RV)>upper limit of normal. Expressions of reversibility: Δvariable=(ABD-BBD) values; Δinit%=Δvariable/BBD value and Δref%=Δvariable/reference value. A 12%init and a 0.2L increase in either FEV1 or FVC or a 10%ref or - 300 mL decrease in RV were considered as clinically significant. RESULTS: Over the 85 smokers without airflow obstruction, 68% had LH. In the hyperinflated group (n=314), and compared to changes in FEV1 and FVC, these RV changes detected more respondents (54% for FEV1 and FVC vs. 65% for RV, P=0.002). This was not the case for the group free from LH (n=52) (23% for FEV1 and FVC vs. 35% for RV, P=0.09). In the 58 hyperinflated groups free from airflow obstruction, and compared to changes in FEV1 and FVC, changes in RV detected more respondents (24% for FEV1 and FVC vs. 71% for RV, P=0.0001). CONCLUSION: In heavy smokers, it seems essential to include LH as a criterion for a positive diagnosis of COPD and of reversibility evaluation.

Modification in swallowing and ventilation co-ordination during hypercapnia, hypoxia, and tachypnea in unrestrained animals.

BACKGROUND: It has been demonstrated that aspirations could occur during respiratory failure, explained by a lack of co-ordination between swallowing and ventilation. To test this hypothesis, we examined the co-ordination of ventilation and swallowing in a completely unrestrained rat model during different level of hypercapnia, during hypoxia, and during tachypnea. METHODS: A total of 50 male Wistar rats (250-350 g) were studied in a barometric plethysmograph to analyze swallowing and ventilation during swallowing, at different gas concentration [room air (G1), 10% of O2 and 0% of CO2 (G2), 21% of O2 and 5% of CO2 (G3), 21% of O2 and 10% of CO2 (G4), tachypnea (G5)]. KEY RESULTS: During hypoxia, there was no difference between G2 and G1 regarding the swallowing parameters and ventilatory parameters. During hypercapnia, there was an increase in swallowing during inspiration in G4 (16 ± 20%P < 0.01) compared with G1. The analysis of ventilatory parameters during swallowing showed an increase in tidal volume (VT) and mean inspiratory time (VT/TI) (P < 0.001) with no change in respiratory cycle duration (TTOT), inspiratory time (TI), and expiratory time (TE) when compared with G1. During tachypnea (G5), the VT decreased (P < 0.05) without any change in VT/TI. CONCLUSIONS & INFERENCES: Our results on animal demonstrated that hypercapnia increased swallowing during inspiration, which was not the case for tachypnea or hypoxia, and could explain some aspirations during respiratory failure.

[Evaluation of the deficiency and the submaximal exercise capacity in obstructive sleep apnoea patients]. / Exploration de la déficience et de l'incapacité des patients atteints d'un syndrome d'apnées hypopnées obstructives du sommeil.

BACKGROUND: In addition to excessive daytime somnolence, exercise limitation is a likely consequence of the cardiorespiratory problems that occur in patients who have obstructive sleep apnoea (OSA). However, few studies have evaluated the aerobic capacity of this patient group. AIMS: To evaluate submaximal exercise capacity over the 6-minute walking test (6-MWT). To determine the factors that influence 6-minutes walking distance (6-MWD). INCLUSION CRITERIA: 120 consecutive patients with severe OSA treated by continuous positive airway pressure who were medically stable will be included. EXCLUSION CRITERIA: 6-MWT contraindications, orthopaedic or rheumatologic diseases likely to influence walking capacity and corticosteroid therapy. INVESTIGATIONS: polysomnography, electrocardiogram, plethysmography, and two 6-MWT's. Indicators of impaired exercise capacity: stops during the walk, 6-MWD less than or equal to predicted lower limit of normal, end walking dyspnoea greater than or equal to 5/10, oxygen saturation fall greater than or equal to five points, end walking heart rate less than or equal to 60 % maximal predicted. Data from our obese patients aged 40-60 years old will be compared with data from 45 age-matched obese subjects free from OSA. EXPECTED RESULTS: OSA will significantly affect the submaximal exercise capacity and will accelerate the ageing of the cardiorespiratory-muscle chain. Submaximal exercise capacity of obese subjects having OSA, compared to subjects free from OSA, will be significantly deteriorated. 6-MWD of OSA patients will be significantly influenced by: resting plethysmographic data, apnoea hypopnoea index, arterial hypertension, obesity or smoking histories.

Obesity induced bronchopulmonary hyperresponsiveness in Tunisian women.

OBJECTIVE: The specific objective of this investigation was to determine whether bronchopulmonary responsiveness (BPR) to methacholine (MCH) was associated with the body mass index (BMI) of Tunisian women. SUBJECTS: In all, 160 healthy nonsmoker women (52 lean, 45 overweight and 63 obese) were recruited and examined in the Clinical Laboratory of Physiology located in the Medical School of Sousse. The average ages (+/-s.e.) of the three categories of lean, overweight and obese subjects were 27.7+/-1.1, 33.2+/-1.7 and 37.5+/-1.3 years, respectively. Their corresponding mean BMIs (+/-s.e.) were 21.9+/-0.3, 27.7+/-0.2 and 36.5+/-0.8 kg m(-2), respectively. MEASUREMENTS: Before their inclusion into the study, subjects were screened for their lung status by measuring their pulmonary function testing parameters using a whole body plethysmograph. BPR was assessed, using a cumulative concentration response curve technique, by measuring with a spirometer the decrease in forced expiratory volume in 1 s (FEV(1)) in response to a cumulative dose of MCH. RESULTS: After adjusting for age, significant differences in both FEV(1) and forced vital capacity (VC) were found between the obese and lean groups (P<0.01), as well as between the obese and overweight groups (P<0.01). In addition, forced expiratory flow between 25 and 75% of VC was significantly different between the obese and lean groups (P<0.001), as well as between the lean and overweight groups (P=0.015). The mean maximum fall of FEV(1) in response to MCH challenge was significantly higher for the obese group (12.0%) than for the overweight (9.8%) or the lean (6.6%) group (P<0.01). Furthermore, the efficacy of the MCH agonist promoting the maximal response (E(max)) and its potency or effective dose producing 50% of the maximal response (ED(50)) were both associated with BMI (the higher the BMI, the higher the E(max) and the lower the ED(50)). CONCLUSION: Our data clearly show that obesity affects pulmonary function performance in Tunisian women by potentially promoting their bronchial hyperreactivity as suggested by the significant correlation between their BMI and the efficacy of the MCH, as well as its potency.