Most patients with juvenile- and adult-onset Pompe disease have difficulties coughing that put them at an increased risk for respiratory problems, but few of them incorporate techniques of pulmonary hygiene into their daily routines, a small study suggests.
The study, “Cough Effectiveness and Pulmonary Hygiene Practices in Patients with Pompe Disease,” was published in the journal Lung.
Pompe disease can develop as a rapidly progressive, severe disease in the first months or first year of life— infantile-onset Pompe disease — or as a slowly progressive, milder form later in life, during childhood or adulthood — late-onset Pompe disease.
These patients often have difficulties breathing and coughing due to weakness in the respiratory muscles. An impaired ability to cough leads to ineffective airway clearance, resulting in mucus accumulation in the lungs, which is associated with an increased risk of respiratory infections.
While there are several reports on how respiratory muscle weakness affects breathing, its impact on coughing capacity, airway clearance, and pulmonary hygiene practices — involving cough augmentation and secretion removal techniques — is still largely unclear.
Cough capacity can be easily assessed through a fast, noninvasive test that measures peak airflow generated during coughing, or the peak cough flow (PCF).
Physicians make decisions on prescribing cough assistance therapies based on ranges of PCF values according to neuromuscular guidelines for adults: normal cough capacity, above 270 L/min; at risk of cough problems, between 160-270 L/min; and ineffective cough, below 160 L/min.
In patients with PCF values below 270 L/min, pulmonary hygiene techniques should be applied when needed, while in patients with ineffective coughing ability, these techniques should be incorporated into their daily routines.
Researchers have now evaluated potential factors that may influence coughing capacity in Pompe disease patients and whether pulmonary hygiene practices are being applied accordingly.
The team conducted clinical pulmonary function tests and measured the coughing capacity in 27 patients with Pompe disease: seven with infantile-onset, six with juvenile-onset, and 14 with adult-onset. Patient ages ranged from 1 to 70 years old.
The type and frequency of pulmonary hygiene practices employed were assessed through interviews with the patients or their caretakers.
Compared with patients with late-onset disease, those with infantile-onset tended to require assisted ventilation for a longer period; were more likely to have a tracheostomy; had significantly lower PCF values; and were more frequently subjected to pulmonary hygiene. These results were in accordance with their more severe disease, and lower PCF values were also related to their smaller stature.
However, the team noted that adult guidelines for PCF thresholds have not been validated in pediatric patients, meaning additional studies are required to establish appropriate PCF thresholds for these younger patients.
Next, the researchers focused on the juvenile- and adult-onset patients. There were no differences in PCF values between the two groups. Among these patients, nine had an ineffective cough, five were at risk for cough problems, and six had normal coughing capacity.
Additional analysis showed their cough capacity differed with assisted ventilation status, with patients who required daytime ventilatory support having significantly lower PCF values, compared with those who required it only at night or not at all.
These differences in cough capacity were strongly associated with cough volume acceleration and cough inspiratory volume. However, cough timing was stable until patients required daytime ventilatory support, suggesting that nerve cell dysfunction “did not alter coordination of the voluntary cough motor program until patients developed severe hypoventilation [breathing problems],” the researchers wrote.
Regarding pulmonary hygiene practices, the researchers found that only infantile-onset patients consistently reported the use of these practices, while most of the patients at risk or with ineffective cough did not use them on a daily basis.
Among the five patients at risk of cough problems, none used secretion management techniques and only one practiced airway clearance strategies. Of the nine patients with ineffective cough, routine secretion management practices were reported by only one patient, while four patients did not use it at all; and airway clearance techniques were applied routinely only in four patients, while two patients reported no use.
“In this sample, the majority of patients with juvenile- and adult-onset Pompe disease had a PCF that placed them at risk for airway clearance problems, yet relatively few incorporated pulmonary hygiene into their daily routine,” the team wrote.
They concluded that “patients at risk for problems or with ineffective PCF should be urged to complete routine pulmonary hygiene.”