Does Pulmonary Function Testing Affect Autonomic Nervous System Activity?

Background The autonomic nervous system (ANS) regulates vital functions such as heart rate and respiration. Pulmonary function tests (PFT) involve forced breathing maneuvers that may influence ANS activity. However, the extent of this interaction remains unclear. Understanding this relationship is important for ensuring accurate autonomic measurements during clinical assessments. This study aims to investigate the effects of pulmonary function tests on the ANS and scientifically determine the interaction between these two systems and the accuracy of the test order. Methods The study was conducted with 48 volunteer students. Participants were selected based on specific health criteria and informed about the study, with their consent obtained. Pulmonary function tests were measured and recorded using the Medwelt SP10 spirometer. Autonomic nervous system activity was assessed using heart rate variability (HRV) analysis with the Elite HRV Corsense device. HRV measurements were taken in a seated position, followed by a 5-minute rest, after which a second measurement was performed. Subsequently, a pulmonary function test was conducted, and a third measurement was taken. Results The study was completed with 48 participants, including 32 women and 16 men, with a mean age of 19 ± 0.92 years. When comparing the first and second HRV measurements, a statistically significant increase was observed only in the Root Mean Square of Successive Differences (RMSSD) parameter. In contrast, no significant changes were detected in other autonomic activity values. In the comparison between the second measurement and the third measurement taken after the pulmonary function test, no changes were observed in RMSSD and average heart rate, but statistically significant changes were detected in Low Frequency (LF), High Frequency (HF), and LF/HF parameters. Conclusion The findings indicate that respiratory maneuvers may specifically affect the reactivity of the parasympathetic system. The difference between the first two measurements highlights the importance of rest duration for reliably measuring autonomic activity. The changes observed in measurements taken after the pulmonary function test suggest that these tests can temporarily affect autonomic nervous system activity and that measurements taken before the test provide more reliable results for accurate evaluation.