- Scenario three – analysing the ABG results

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• The patient’s PaO₂ is >10 kPa indicating he is not hypoxaemic. However, we would expect a much higher PaO[sub]2[/sub] being ventilated with 85% oxygen. This indicates severely impaired oxygenation
• His pH is 7.10, much lower than normal indicating that he has an acidaemia
• His PaCO[sub]2[/sub] is very high which is consistent with his low pH and so he has a respiratory acidosis. This is due to the period of apnoea and his underlying COPD
• His bicarbonate and base excess are both increased, indicating a metabolic alkalosis. This is a compensatory mechanism for his longstanding COPD. Prior to his respiratory arrest this compensation would have resulted in his pH being almost normal despite an increased PaCO[sub]2[/sub]

In summary:

The significant acidaemia (pH 7.10) indicate an additional acute respiratory acidosis as a result of the respiratory arrest. In the pre-existing compensated chronic respiratory acidosis, the pH would have been close to normal. Treatment will include, if appropriate, non-invasive ventilation or tracheal intubation and ventilation.

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That is not right.

• The patient’s PaO₂ is >10 kPa indicating he is not hypoxaemic. However, we would expect a much higher PaO[sub]2[/sub] being ventilated with 85% oxygen. This indicates severely impaired oxygenation
• His pH is 7.10, much lower than normal indicating that he has an acidaemia
• His PaCO[sub]2[/sub] is very high which is consistent with his low pH and so he has a respiratory acidosis. This is due to the period of apnoea and his underlying COPD
• His bicarbonate and base excess are both increased, indicating a metabolic alkalosis. This is a compensatory mechanism for his longstanding COPD. Prior to his respiratory arrest this compensation would have resulted in his pH being almost normal despite an increased PaCO[sub]2[/sub]

In summary:

The significant acidaemia (pH 7.10) indicate an additional acute respiratory acidosis as a result of the respiratory arrest. In the pre-existing compensated chronic respiratory acidosis, the pH would have been close to normal. Treatment will include, if appropriate, non-invasive ventilation or tracheal intubation and ventilation.

Feedback

That is right.

• The patient’s PaO₂ is >10 kPa indicating he is not hypoxaemic. However, we would expect a much higher PaO[sub]2[/sub] being ventilated with 85% oxygen. This indicates severely impaired oxygenation
• His pH is 7.10, much lower than normal indicating that he has an acidaemia
• His PaCO[sub]2[/sub] is very high which is consistent with his low pH and so he has a respiratory acidosis. This is due to the period of apnoea and his underlying COPD
• His bicarbonate and base excess are both increased, indicating a metabolic alkalosis. This is a compensatory mechanism for his longstanding COPD. Prior to his respiratory arrest this compensation would have resulted in his pH being almost normal despite an increased PaCO[sub]2[/sub]

In summary:

The significant acidaemia (pH 7.10) indicate an additional acute respiratory acidosis as a result of the respiratory arrest. In the pre-existing compensated chronic respiratory acidosis, the pH would have been close to normal. Treatment will include, if appropriate, non-invasive ventilation or tracheal intubation and ventilation.