Neurophysiological changes in COPD patients with chronic respiratory insufficiency

Area of Science:

• Neurology
• Pulmonology
• Clinical Electrophysiology

Background:

• Chronic hypoxemia is a known complication of chronic obstructive pulmonary disease (COPD).
• Peripheral neuropathy (PNP) is frequently observed in COPD patients, but its prevalence and central nervous system (CNS) involvement require further investigation.

Purpose of the Study:

• To determine the prevalence of PNP in COPD patients with chronic hypoxemia.
• To investigate potential changes in the CNS, particularly the brainstem, in these patients.

Main Methods:

• 32 COPD patients were divided into two groups based on PaO2 levels (hypoxemic vs. non-hypoxemic).
• Evaluations included motor and sensory nerve conduction studies (MNCV/SNCV), electromyography, visual evoked potentials (VER), and brainstem auditory evoked potentials (BAER).

Main Results:

• PNP was detected in 93.8% of all COPD patients studied.
• Sural nerve latency correlated with smoking and reduced peak expiratory flow rate (PEFR).
• Median nerve conduction velocity decreased with elevated PaCO2 and lower pH. BAER latencies (III, I-III, III-V) showed significant correlations with respiratory function parameters and blood gas levels, indicating brainstem involvement.

Conclusions:

• The high prevalence of PNP in COPD patients with hypoxemia underscores the systemic impact of the disease.
• Evidence suggests that chronic hypercapnia and respiratory acidosis in COPD patients not only cause PNP but also lead to delayed brainstem auditory evoked responses, indicating CNS compromise.