Respiratory Therapist/abg and Fio2


when calculating abg's, do you have to take fio2 into account especially when on vent

Hi Steve,

Thanks for trusting me with your question today. The short answer to your question is Yes, it is necessary to provide the FiO2 when submitting a Blood Gas to Lab, because one of the values an ABG gives you is PaO2 (which is affected by your FiO2) which tells us the partial pressure of oxygen in the arterial blood. As an aside, some Labs will even REFUSE to process an ABG sample without an FiO2 recorded, because the ABG result would be virtually meaningless if it is missing such a key variable as FiO2.

Generally, in a perfect world, the higher the FiO2 a patient is on, the higher their PaO2 will be...this applies all the time, accross the board whether a patient is on a simple 2 Liter nasal cannula, or on a ventilator at 100% oxygen.  I hope this helps.

Best of health to you!

Larry, RRT  

Respiratory Therapist

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Larry W. Wical, BA-RRT


I CAN answer: ALL questions and queries related to the following topics... - Oxygen - Asthma - COPD - Bronchitis - Emphysema - Pneumonia (Viral/Bacterial) - Tuberculosis (TB) - SARS - Influenza (Flu) - Vaccines - Pulmonary Embolism - Pleural Effusion - Atelectasis - Inhalation injuries (burns, chemicals, etc.) - PFTs - Cardiovascular health - Sleep Apnea - BiPap/CPAP - Ventilators ("Respirators") - Aspiration injuries - Thoracic injuries - Lung contusions - Tracheal injuries - Artificial Tracheostomy - Secretions - Prolotherapy/Regenerative Injection Therapy (RIT): A patient's experience/perspective - General health and fitness I CANNOT answer: Questions that vary too far from my primary scope of pulmonary and cardiovascular care and fitness. I promise to be open and honest about my knowledge of submitted topics, and will always openly provide my personal as well as professional feedback as it relates.


Registered Respiratory Therapist (RRT, RCP) since 2005. I have worked primarily in the acute care, critical care, burn care and home care settings.

NBRC - National Board of Respiratory Care AARC - American Association of Respiratory Care

-All About Kids Magazine -The Clermont Sun -Cincy Sports & Fitness Magazine -Many online Fitness and Health blogs and "webazines"

- B.A. in Communication (1997) - A.A.S. in Respiratory Science (2005) - RRT license (state of OH, KY and IN) - Basic Life Saving (BLS) - Advanced Cardiovascular Life Support (ACLS) - Advanced Burn Life Support (ABLS)

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Currently work in the city's largest academic/research hospital.

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