Phrenic Nerve Conduction Reference Values in Healthy Adults: An Exploratory Cross-Sectional Study in a Mexican Population.

Background/Objectives: Phrenic nerve conduction (PNC) studies are essential for evaluating respiratory dysfunction and neuromuscular disorders. Despite international reference data, no normative values exist for the Mexican population. This study aimed to establish reference values for PNC latency and amplitude in healthy Mexican adults. Methods: We conducted a cross-sectional study between June 2022 and February 2023 including healthy adults (>18 years). Bilateral PNC studies were performed using surface electrodes and a 4-channel stimulation device. Latency and amplitude were recorded, and demographic and anthropometric data were collected. Results: Fifty subjects (22 women, 44%; 28 men, 56%) were enrolled. Mean latency was 6.10 ms (SD ± 1.48), and mean amplitude was 0.60 mV (SD ± 0.20). Significant differences were observed in left phrenic nerve latency between women and men (median 5.83 vs. 6.37 ms, p = 0.0348) and in amplitude between left and right phrenic nerves (0.55 vs. 0.65 mV, p = 0.0036). No significant correlations were found between latency and age or between amplitude and thoracic perimeter; however, the correlation coefficient suggests a positive relationship for both that should be confirmed in future studies with a larger sample size. Conclusions: This is the first report of PNC normative values in Mexican adults. Findings are consistent with international data and provide locally relevant reference values. Larger multicenter studies are warranted to validate and expand these results.