What can I fix with ventilation?

Let’s review what we have discussed in previous chapters. We know that with mechanical ventilation, we often have to intubate patients who are having difficulty regulating their CO₂ and O₂ levels. Patients can be intubated due to ventilatory failure (increasing CO₂, hypercarbia) or due to hypoxia (decreasing oxygen levels). We have discussed how changing CO₂ levels in the body can affect the overall pH of the body, which we can measure using an ABG. Often, the decision to intubate a patient is directly due to the ABG results that are being seen.

In an ABG, we know that we have values for pH, pCO₂, pO₂ and HCO₃. Which values can be affected by ventilation and which ones cannot?

You guessed it! CO₂ is directly affected by ventilation, while HCO₃ cannot be changed by ventilation and must be regulated by the kidneys. Therefore, the pH can be affected in ventilation only by affecting the CO₂ and not the “bicarb” (bicarbonate). In addition, the pO₂ can also be directly impacted by affecting how much oxygen we are delivering effectively to the lungs.