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. 2022 Jun 28:13:938256.
doi: 10.3389/fneur.2022.938256. eCollection 2022.

Comparison of Slow and Forced Vital Capacity on Ability to Evaluate Respiratory Function in Bulbar-Involved Amyotrophic Lateral Sclerosis

Xin Huang  1   2   3 , Chenfang Du  1 , Qiong Yang  1   2   3 , Dongsheng Fan  1   2   3
Affiliations

Comparison of Slow and Forced Vital Capacity on Ability to Evaluate Respiratory Function in Bulbar-Involved Amyotrophic Lateral Sclerosis

Xin Huang et al. Front Neurol. .

Abstract

Background and objective: The percent-predicted forced vital capacity (FVC%) in the pulmonary function test (PFT) is generally used to evaluate the respiratory function in amyotrophic lateral sclerosis (ALS). The slow vital capacity (SVC) is another method to evaluate the respiratory function. Some neurologists found that the FVC% was not reflective of respiratory symptoms and the percent-predicted SVC (SVC%) was found to be higher in some patients with bulbar-onset ALS. We aimed to compare the percent predicted SVC (SVC%) with FVC% in evaluating the respiratory function and investigate the associations between the associations between clinical characteristics and the difference between the SVC% and the FVC% (SVC%-FVC%) in bulbar-involved ALS patients.

Method: This prospective study included patients with bulbar-involved ALS who visited the Peking University Third Hospital between October 2020 and November 2021. They underwent comprehensive clinical assessments, including bulbar symptom assessments, revised ALS functional rating scale (ALSFRS-R), Rasch-Built Overall Amyotrophic Lateral Sclerosis Disability Scale (Roads), and PFTs. The group differences were analyzed using parametric and non-parametric tests.

Results: A total of 59 participants were initially enrolled, and 51 of them were included in the final analysis. In patients with bulbar-involved ALS, the SVC% (73.82 ± 21.95%) was significantly higher (p = 0.013) than the FVC% (71.42 ± 23.15%). After controlling for other relevant variables, a partial correlation analysis showed a significant correlation (r = -0.352, p = 0.041) between ALSFRS-R1 score and SVC%-FVC%.

Conclusion: Our prospective study found that the SVC% was significantly higher and more reflective of actual respiratory function than the FVC% in patients with bulbar-involved ALS. Furthermore, the severity of dysarthria was found to be positively correlated with SVC%-FVC%, providing a clinical marker for predicting SVC%-FVC%.

Keywords: amyotrophic lateral sclerosis; bulbar-involved; dysarthria; forced vital capacity; respiratory function tests; slow vital capacity.

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Conflict of interest statement

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

Figure 1
Figure 1
Flowchart of our study. A schematic summarizing the number of patients during participation and inclusion. ALS, amyotrophic lateral sclerosis; PFTs, pulmonary function tests.
Figure 2
Figure 2
Comparison of SVC% and FVC% in bulbar-involved ALS (n = 51). SVC% (73.82 ± 21.95) was significantly higher than FVC% (71.42 ± 23.15). SMD = 0.51. p = 0.013. SVC%, percent predicted SVC values; FVC%, percent predicted FVC values; ALS, amyotrophic lateral sclerosis; SMD, standardized mean difference. *p < 0.05.
See this image and copyright information in PMC

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