Hypercapnic ventilation response in patients with lung disease: improved accuracy by correcting for ventilation...

Area of Science:

• Respiratory Physiology
• Pulmonary Medicine
• Clinical Investigation

Background:

• The hypercapnic ventilation response (HCVR) is influenced by lung function, specifically forced expired volume in 1 s (FEV1).
• Low FEV1 in individuals with small stature or lung disease leads to reduced HCVR values.
• Indexing HCVR by predicted maximal voluntary ventilation (MVV) yields a corrected HCVR (CHCVR) independent of FEV1 in healthy subjects.

Purpose of the Study:

• To evaluate the utility of CHCVR in assessing chemosensitivity in patients with compromised lung function.
• To compare the diagnostic performance of CHCVR against standard HCVR and occlusion pressure response to hypercapnia (OPRH).

Main Methods:

• A linear regression model (MVV = 31.2 x FEV1 + 11.8) was established using data from 411 patients to predict MVV.
• HCVR and CHCVR were compared with OPRH in 34 patients with chronic obstructive pulmonary disease (COPD) and 19 patients with low FEV1 due to small stature.
• Sensitivity, specificity, positive predictive value, negative predictive value, and accuracy were calculated for both HCVR and CHCVR.

Main Results:

• In COPD patients, standard HCVR showed high sensitivity (86%) and negative predictive value (94%) but low specificity (59%), positive predictive value (35%), and accuracy (65%).
• In contrast, CHCVR demonstrated high values across all metrics: sensitivity (86%), negative predictive value (96%), specificity (100%), positive predictive value (100%), and accuracy (97%).
• Similar results were observed in the group of patients with low FEV1 due to small stature.

Conclusions:

• The corrected HCVR (CHCVR) provides a more accurate assessment of chemosensitivity in patients with ventilation limitations compared to standard HCVR.
• CHCVR is a valuable tool for evaluating respiratory control in patients with poor lung function, including those with COPD or low FEV1.
• This method offers improved diagnostic accuracy for chemosensitivity assessment in challenging patient populations.