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?

Apply Your Learning

Think about how the body normally tries to fix acid-base imbalances. Which of the compensation mechanisms is related to breathing? Which value is not related to breathing? If you have difficulty answering, please refer to Chapter 8. Then, read on for the answer…

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.

Key Takeaways

For ABGs with acid-base imbalances, remember that HCO3 cannot be affected by ventilation. CO2 is the main component that is affected by breathing and mechanical ventilation. The ultimate goal of fixing ABG acid base issues is to maintain a normal pH. Sometimes you will drive your CO2 slightly outside of normal ranges to correct an abnormal pH.
Health care workers wearing full protective bodysuits with masks and face shields
During the COVID-19 pandemic, many health care workers needed to gain increased familiarity with ventilation. Perhaps you were one of them!

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