Source: Am Fam Physician  |  Posted 8 years ago

Variation of peak inspiratory flow (PIF) in children using commonly prescribed dry powder inhalers (DPIs) appears to be significantly affected by their age and the severity of their symptoms.

Efficacy of metered-dose inhalers plus spacers and DPIs depends on a sufficiently high PIF. However, few studies have evaluated PIF in children, write Arvid W.A. Kamps, MD, PhD, Department of Pediatrics, at Klinieken, Zwolle, The Netherlands, and colleagues.

Dr. Kamps and colleagues analysed the effects of age, inhaler device and severity of symptoms on PIF variation in 24 girls and 34 boys who were 4 to 15 years old and were using the Accuhaler[^]TM[] or Turbohaler[^]TM[] for treatment of asthma.

Patients recorded PIF values and asthma symptoms twice daily for 4 weeks. PIF was measured with a portable PIF-meter equipped with adapters to simulate flow resistance through the inhalers.

Children generated higher PIF values through the Accuhaler than through the Turbohaler. However, mean PIF values increased with age, independent of type of inhaler used.

The average variation of PIF was 72.3% for patients using the Accuhaler adapter and 67.0% for patients using the Turbohaler adapter (mean difference, 5.2%). Children 7 years of age or younger had a significantly greater variation of PIF in addition to a lower mean PIF ([]P[] = .0003).

Most patients generated PIF >30 L/minute during the study, even when they experienced symptoms of asthma. However, PIF decreased significantly when symptoms of asthma increased ([]P[] < .01) although the correlation between PIF and morning and evening symptoms was weak.

Patients who reported moderate or severe symptoms during the study period had a significantly greater variation of PIF compared to patients who remained free of symptoms or reported mild symptoms, the researchers report.

"The variation of PIF through the Accuhaler and Turbohaler adapter was significantly greater for children 7 years of age or younger and for patients experiencing moderate or severe symptoms of asthma," Dr. Kamps and colleagues conclude.