An indirect assessment of the functioning of smooth muscle activity in the airways and gastrointestinal wall may help explain the common pathophysiology that links these 2 common childhood conditions.
According to a recent report, gastric motor functions were significantly impaired in children with asthma, children with functional abdominal pain disorder (FAPD), and children with both disorders.
FAPDs are stomach aches that cannot be explained by any visible or detectable abnormalities after examination and tests, if necessary. These unexplained gastrointestinal pains are very common in children all over the world. According to the Rome IV classification, there are 4 types of pediatric FAPD: functional dyspepsia (FD), irritable bowel syndrome (IBS), functional abdominal pain unspecified (FAP-NOS) and abdominal migraine.
Asthma is also a global health problem for children. The researchers said they undertook the study because previous work had shown a link between FAPD and asthma, but why such a link exists is unclear.
Using gastric motility and lung function tests, they hoped to identify possible underlying pathophysiological mechanisms, with the hypothesis that “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, included 4 study groups: asthma only, FAPD only, asthma and FAPD, and healthy controls; 24 children, aged 7 to 12, were recruited for each group.
Asthma was diagnosed using patient history and bronchodilator reversibility testing.
Pulmonary function parameters, recorded by spirometry, were forced vital capacity (FVC); forced exhaled volume in the first second (FEV1); forced expiratory flow between 25% and 75% (FEF 25%-75%); forced expiratory flow at 50%; and peak expiratory flow.
The diagnosis of FAPD was made using the Rome IV criteria; all participants underwent ultrasound assessment of gastric motility. Gastric emptying rate was calculated after 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 parameters of gastric motility, gastric emptying rate, amplitude of antral contraction and antral motility index, were significantly impaired in children with FAPD only, children with asthma only, and children with asthma and FAPD , compared to healthy controls (P
Pulmonary function parameters indicative of airway obstruction (FEV1/FVC ratio, FEF25-75%) were only altered 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 with both diseases.
Additionally, researchers observed a positive correlation in children with both FAPD and asthma between antral motility index and lung function parameters, indicating airway obstruction in children with both. troubles. This was not observed in children with FAPD alone, or in those with asthma alone.
The links between the 2 diseases could come from a “primary disturbance of the activity of the smooth muscles of the airways and the gastrointestinal wall, which could be a possible physiopathological mechanism of this association between asthma and FAPDs” .
The researchers said that to their knowledge, this was 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 lung 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.