Introduction Spirometry plays an important role in the assessment of
possible respiratory failure in children with neuromuscular disorders
(NMDs). However, obtaining reliable spirometry results is a major
challenge. We studied the relation between Forced Oscillation Technique
(FOT) and spirometry results. FOT is an easy, non-invasive method to
measure respiratory mechanics, i.e. respiratory resistance R and
respiratory reactance X. We hypothesized an increased resistance R and
reduced reactance X in patients with more reduced lung function. Methods
In this prospective single center study we included all children with
NMDs able to perform spirometry. We consecutively measured respiratory
resistance R and reactance X at 5, 11 and 19 Hz and (Forced) Vital
Capacity, Peak Expiratory Flow. Spearman correlation coefficients were
calculated and regression curves were estimated. Results We included 148
patients, with a median age of 13 years (IQR 8-16). All correlation
coefficients were statistically significant with p = 0.000. A negative
correlation was found between resistance R and spirometry outcomes
(spearman correlation coefficient (ρ) between -0.5 and -0.6). A positive
correlation was found between reactance X (i.e. less negative outcomes)
and spirometry outcomes (ρ between 0.4 and 0.6). Highest correlation was
found at lower frequencies. Regression analysis showed a non-linear
relation between FOT and spirometry results. Conclusion We found a
non-linear relation between FOT and spirometry results with increased
resistance R and reduced reactance X in patients with more restrictive
lung function decline. Given the difficulties with performing
spirometry, FOT may be a promising surrogate measure of lung function.
Forced Oscillation Technique for Monitoring the Respiratory Status of Children with Cystic Fibrosis: A Systematic Review