Improving Oxygenation & Ventilation

The numbers represent:

pH: 7.25 (7.35-7.45)

pCO2: 52 (35-45)

paO2: 70 (86-100)

HCO3: 24 (22-26)

You astutely realize that the pCO2 is elevated and the pH is decreased indicating a respiratory acidosis. You also notice that the paO2 is low. You know you can help by adjusting the ventilation and oxygenation, but how?!


  • It is the exchange of air between the lungs and the ambient air (air being delivered by ventilator) – moving air into and out of the lungs
  • Primary way to remove CO2 (carbon dioxide) from the body is through ventilation
  • Measure this with minute ventilation – as this can quantify the amount of CO2 being removed
  • Minute Ventilation = respiratory rate (RR) x tidal volume (Vt)

For this patient, you can consider increasing the RR or tidal volume to help blow off more CO2 and improve the respiratory acidosis.


  • Helps provide greater oxygen supply to the lungs, which then supplies more oxygen to the rest of the body
  • Can increase the fraction of inspired oxygen (FIO2) or the positive end-expiratory pressure (PEEP)
  • FIO2 is the percentage of oxygen mixed in the air delivered to a patient
    • Normal FIO2 is 21%, whereas mechanically vented patients can get up to 100% oxygen
  • PEEP is the positive pressure that remains in the lungs at the end of expiration (to help keep alveoli open)
    • Starting PEEP is typically at 5 cm of H2O

For this patient, to improve oxygenation, you can consider increasing the FIO2 or PEEP depending on the current vent settings of this patient.


Kaufman, D. (n.d.). Interpretation of Arterial Blood Gases (ABGs). Retrieved January 22, 2021, from

Mora Carpio AL, Mora JI. Ventilator Management. [Updated 2020 May 17]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-. Available from: