Introduction: The Foundation of Reliable Oxygenation Research   Controlled desaturation studies are central to validating  pulse oximeters . These studies, performed in specialized hypoxia laboratories  such as PRL, safely lower arterial oxygen saturation (SaO₂) to predefined plateaus, typically from %100 to 70% SaO₂, generating reference data used to calibrate or verify pulse oximeters.  At the core of this process lies one indispensable element: accurate blood gas analysis