Isolated Elevation in Lung Residual Volume Is Associated With Airway Diseases

Area of Science:

• Pulmonary Medicine
• Radiology
• Clinical Diagnostics

Background:

• Residual volume (RV) is a lung function parameter often associated with air trapping in obstructive lung diseases.
• The clinical significance of an isolated increase in RV, without other pulmonary function test (PFT) abnormalities, remains unclear.
• This study aimed to investigate the clinical and radiological characteristics of patients with an isolated elevation in RV.

Purpose of the Study:

• To evaluate the clinical significance of an isolated elevation in residual volume (RV).
• To identify associated radiologic findings in patients with isolated RV elevation.
• To determine if isolated RV elevation indicates underlying airway-centered lung diseases.

Main Methods:

• Retrospective analysis of outpatient PFT database (2016-2018) at Mayo Clinic.
• Defined isolated RV elevation as RV ≥ upper limit of normal or ≥ 130% predicted with normal total lung capacity (TLC), spirometry, and diffusion capacity (D_LCO).
• Matched patients with high RV to a control group with normal PFTs by age and sex.

Main Results:

• 169 subjects with isolated RV elevation were identified, with a median age of 73.
• High RV group showed increased prevalence of smoking history, asthma, non-tuberculous mycobacterial infections, bronchiectasis, bronchial thickening, mucus plugging, and emphysema compared to the normal RV group.
• Significant differences were observed in RV (3.08 L vs 2.26 L, P < .001) and various clinical and radiological parameters between the groups.

Conclusions:

• Isolated elevation in residual volume (RV) on PFTs is a clinically relevant finding.
• This abnormality is associated with airway-centered diseases.
• Elevated RV alone may signify underlying pulmonary conditions requiring further investigation.