This study aims to compare lung perfusion distribution between inspiratory breath-hold and expiratory breath-hold phases using the saline indicator method combined with electrical impedance tomography (EIT). A self-controlled crossover design will be used in which each participant undergoes both breath-hold conditions with standardized rapid intravenous saline injections. The primary objective is to evaluate changes in global and regional pulmonary perfusion under different lung volume states. The findings may improve understanding of perfusion redistribution with lung inflation and support optimized ventilatory strategies in clinical practice.
Age 18 to 65 years
Able to provide written informed consent
Able to perform standardized inspiratory and expiratory breath-hold maneuvers for at least 8 seconds
No known acute cardiopulmonary disease
Known severe cardiopulmonary disease (e.g., advanced chronic obstructive pulmonary disease, severe pulmonary hypertension, or heart failure)
Hemodynamic instability or clinically significant cardiac arrhythmia
Contraindication to intravenous saline administration or fluid bolus
Pregnancy or breastfeeding