Physiological Role of Functional Residual Capacity and Gas Dynamics During Breath Holding

Dr. Aniket Sharma

Abstract: Background: Breath holding is a voluntary or reflex activity influenced by pulmonary volumes, gas exchange mechanisms, and neural regulation of respiration. Objective: To understand the role of Functional Residual Capacity (FRC), oxygen flux, oxygen utilization, and carbon dioxide accumulation during breath holding, and how these factors determine the duration and physiological limits of apnea. Methods: This is a narrative physiological review discussing established mechanisms based on foundational pulmonary physiology and gas exchange dynamics. Results: FRC acts as the principal reservoir of oxygen during apnea. Oxygen continues to diffuse into the bloodstream, while tissues utilize it at a steady rate, leading to a gradual decline in PaO? and SpO?. Simultaneously, CO? accumulates due to ongoing metabolism without ventilation, causing a progressive rise in PaCO?. The resulting hypercapnia stimulates central and peripheral chemoreceptors, producing an intense drive to breathe and terminating the breath-hold. Conclusion: FRC significantly determines breath-hold duration by providing initial oxygen reserves. However, it is the rise in PaCO? and associated respiratory drive that ultimately ends voluntary apnea. Understanding these mechanisms is crucial in clinical scenarios involving controlled apnoea, diving, or anaesthetic management.

Keywords: Breath holding, Functional residual capacity, PaO?, PaCO?, Oxygen flux, Apnoea, SpO?, Respiratory physiology

How to Cite?: Dr. Aniket Sharma, "Physiological Role of Functional Residual Capacity and Gas Dynamics During Breath Holding", Volume 14 Issue 7, July 2025, International Journal of Science and Research (IJSR), Pages: 1360-1361, https://www.ijsr.net/getabstract.php?paperid=SR25721233739, DOI: https://dx.doi.org/10.21275/SR25721233739