- Scenario five – analysing the ABG results

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• The patient’s PaO₂ is 17 kPa. This is >10 kPa and is consistent with breathing 30% oxygen. His oxygenation is not impaired
• His pH is well below the lower limit of normal (7.35) and he has a very severe acidaemia
• His PaCO[sub]2[/sub] is low and is not consistent with his pH. This is due to his respiratory system trying to compensate for his acidaemia by hyperventilating and removing CO[sub]2[/sub]. He therefore has a respiratory alkalosis
• He has a massive reduction in bicarbonate (and associated fall in base excess) which has been consumed to buffer the production of ketoacids. He therefore has a severe metabolic acidosis

The patient’s blood glucose is also elevated at 30 mmol l^-1 and his urine is strongly positive for ketones.

In summary:

These blood gas results are consistent with severe diabetic ketoacidosis. Further evidence is the presence of ketones in his urine and the very high blood glucose. There is a primary metabolic acidosis with partial compensation provided by the respiratory alkalosis.

Treatment will include:

• Fluid resuscitation, initially with normal saline
• Insulin, with regular measurement of blood glucose

The use of bicarbonate is controversial but many clinicians would give it in the presence of such a severe acidaemia, particularly if it did not improve rapidly after starting the above measures.

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That is not right. Have another go.

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That is not right.

• The patient’s PaO₂ is 17 kPa. This is >10 kPa and is consistent with breathing 30% oxygen. His oxygenation is not impaired
• His pH is well below the lower limit of normal (7.35) and he has a very severe acidaemia
• His PaCO[sub]2[/sub] is low and is not consistent with his pH. This is due to his respiratory system trying to compensate for his acidaemia by hyperventilating and removing CO[sub]2[/sub]. He therefore has a respiratory alkalosis
• He has a massive reduction in bicarbonate (and associated fall in base excess) which has been consumed to buffer the production of ketoacids. He therefore has a severe metabolic acidosis

The patient’s blood glucose is also elevated at 30 mmol l^-1 and his urine is strongly positive for ketones

In summary:

These blood gas results are consistent with severe diabetic ketoacidosis. Further evidence is the presence of ketones in his urine and the very high blood glucose. There is a primary metabolic acidosis with partial compensation provided by the respiratory alkalosis.

Treatment will include:

• Fluid resuscitation, initially with normal saline
• Insulin, with regular measurement of blood glucose

The use of bicarbonate is controversial but many clinicians would give it in the presence of such a severe acidaemia, particularly if it did not improve rapidly after starting the above measures.

Feedback

That is right.

• The patient’s PaO₂ is 17 kPa. This is >10 kPa and is consistent with breathing 30% oxygen. His oxygenation is not impaired
• His pH is well below the lower limit of normal (7.35) and he has a very severe acidaemia
• His PaCO[sub]2[/sub] is low and is not consistent with his pH. This is due to his respiratory system trying to compensate for his acidaemia by hyperventilating and removing CO[sub]2[/sub]. He therefore has a respiratory alkalosis
• He has a massive reduction in bicarbonate (and associated fall in base excess) which has been consumed to buffer the production of ketoacids. He therefore has a severe metabolic acidosis

The patient’s blood glucose is also elevated at 30 mmol l^-1 and his urine is strongly positive for ketones.

In summary:

These blood gas results are consistent with severe diabetic ketoacidosis. Further evidence is the presence of ketones in his urine and the very high blood glucose. There is a primary metabolic acidosis with partial compensation provided by the respiratory alkalosis.

Treatment will include:

• Fluid resuscitation, initially with normal saline
• Insulin, with regular measurement of blood glucose

The use of bicarbonate is controversial but many clinicians would give it in the presence of such a severe acidaemia, particularly if it did not improve rapidly after starting the above measures.