Related Experiment Videos
The ventilatory response to carbon dioxide in asthmatic children, measured by the mouth-occlusion method (Pm100)
Insights
Asthmatic children show varied responses to carbon dioxide. A new method confirmed increased neurochemical drive in asthma, despite normal average ventilatory responses in some patients.
Area of Science:
- Respiratory Physiology
- Pediatric Pulmonology
- Neuroimmunology
Background:
- Ventilatory responses to carbon dioxide (CO2) in bronchial asthma patients exhibit significant variability.
- Some asthmatic individuals display a high ventilatory response to CO2 even with elevated airway resistance, a paradoxical observation.
Purpose of the Study:
- To investigate the paradoxical ventilatory responses to CO2 in asthmatic children.
- To determine if neurochemical drive is altered in pediatric bronchial asthma.
Main Methods:
- Studied 31 asthmatic children and 22 age-matched healthy children.
- Measured ventilatory response to CO2 using a conventional rebreathing method.
- Utilized a novel index (Pm100) that increases linearly with CO2 concentration.
Main Results:
- Ventilatory response to CO2 varied widely among asthmatic patients, correlating with airway obstruction (FEV1, MMEFR).
- Mean ventilatory response to CO2 was similar between asthmatic and healthy children using the conventional method.
- The novel Pm100 index revealed a significantly higher mean response in asthmatic children compared to controls, despite individual variations.
Conclusions:
- The neurochemical drive to breathe is significantly increased in bronchial asthma.
- The Pm100 index provides a more sensitive measure of altered ventilatory control in asthma than conventional methods.
Abstract:
Ventilatory responses to carbon dioxide vary widely in patients with bronchial asthma; some have a high response despite increased airway resistance. This paradoxical response was studied in 31 asthmatic children and 22 age-matched healthy children. Measurement of the ventilatory response to carbon dioxide with a conventional rebreathing method showed wide variation in the patients, paralleling the degree of their airway obstruction as measured by the one-second forced expiratory volume and maximal midexpiratory flow rate, but their mean response was similar to that in the control subjects. The ventilatory response was then determined with a new index (Pm100), which rises linearly with increasing carbon dioxide concentration. Despite wide variation in the slope of Pm100 in the patients, their mean response significantly exceeded normal, confirming that the neurochemical drive is increased in bronchial asthma.