An indirect assessment of the functioning of smooth muscle activity in the airways and gastrointestinal wall may help explain the shared pathophysiology that links these 2 common childhood ailments.
Gastric motor functions were significantly impaired in children with asthma, children with functional abdominal pain disorders (FAPDs), and children with both disorders, according to a recent report.
FAPDs are stomachaches that cannot be explained by any visible or detectable abnormality after an examination and testing, if required. These unexplained gastrointestinal pains are highly prevalent in children worldwide. According to the Rome IV classification, there are 4 types of pediatric FAPDs: functional dyspepsia (FD), irritable bowel syndrome (IBS), functional abdominal pain-not otherwise specified (FAP-NOS), and abdominal migraine.
Asthma is also a global health problem for children. The researchers said they undertook the study because previous work has shown a link between FAPDs and asthma, but why such a link exists is unclear.
Using gastric motility and lung function tests, they hoped to pinpoint possible underlying pathophysiological mechanisms, with the hypothesis that the “smooth muscle dysfunction is a shared pathophysiological mechanism for the observed association between FAPDs and asthma.”
The cross-sectional comparative study, conducted in Sri Lanka, consisted of 4 study groups: asthma only, FAPDs only, both asthma and FAPDs, and healthy controls; 24 children, aged 7 to 12, were recruited for each group.
Asthma was diagnosed using patient history and the bronchodilator reversibility test.
Pulmonary function parameters, recorded by spirometry, were forced vital capacity (FVC); forced expired volume in the first second (FEV1); forced expiratory flow between 25%–75% (FEF 25%-75%); forced expiratory flow at 50%; and peak expiratory flow rate.
The diagnosis of FAPDs was made using Rome IV criteria; all participants underwent ultrasound assessment of gastric motility. The gastric emptying rate was calculated after the children fasted overnight and then had to drink a liquid meal (200mL of chicken broth) within 2 minutes. Antral motility parameters were obtained within the first 5 minutes after drinking the broth.
All gastric motility parameters, gastric emptying rate, amplitude of antral contraction, and antral motility index, were significantly impaired in children with FAPDs only, children with asthma only, and children with both asthma & FAPDs, compared with healthy controls (P < .05).
Pulmonary function parameters indicating airway obstruction (FEV1/FVC ratio, FEF25-75%) were only impaired in children with asthma and in children with both disorders, but not in FAPD alone. There was no statistically significant difference between children with only asthma and children having both diseases.
Furthermore, researchers observed a positive correlation in children with both FAPD and asthma between the antral motility index and lung function parameters, indicate airway obstruction in children with both disorders. This was not seen in children with FAPD alone, or in those with asthma alone.
The links between the 2 diseases might stem from a "primary disturbance of smooth muscle activity in the airways and gastrointestinal wall, which could be a possible pathophysiological mechanism for this association between asthma and FAPDs."
The researchers said as far as they know, this is the first pediatric study to assess gastric motility and lung function in children with both conditions.
Kumari MK, Amarasiri L, Rajindrajith S, Devanarayana NM. Gastric motility and pulmonary function in children with functional abdominal pain disorders and asthma: A pathophysiological study. PLoS One. Published online January 4, 2022. doi: 10.1371/journal.pone.0262086.