discussion.
So, we gave you the following question to answer this week. It's a pretty bog standard ABG question. But, it also illustrates a couple of points about paediatrics, and we also want to use it to reinforce our statements about writing as scientifically as possible. Our comments are in italics and our answers are in normal text.
A 6 year old boy presents to your department with the ambulance after a seven minute seizure. He is still fitting when he arrives in resus. His distraught mother accompanies him into the resuscitation room.
His prior vital signs with the ambulance include a temperature of 39.6oC.
Access is obtained and an urgent venous gas is obtained.
pH 7.11
pCO2 26 mmHg
pO2 54 mmHg
HCO3- 7 mmol/L
Na+ 140 mmol/L
Cl- 104 mmol/L
Glucose 1.7 mmol/L
Lactate 10.6 mmol/L
Question 1.
Describe the major acid-base disturbances present and give a differential for each.
When approaching these questions, we would reiterate it is important to be as scientific and concise as possible.
This patient has a profound acidaemia, with a bicarb of 7. There is therefore a metabolic acidosis.
Defining the metabolic acidosis we find an AG = 140 - 7 - 104 = 29. This yields a delta ratio of (29-12)/(24-7) = 17/17 = 1.0. Therefore we have an isolated RAGMA.
We expect our CO2 = 8 + 1.5 x 7 = 18.5. This patient has a higher CO2 and therefore has a relative respiratory acidosis.
Therefore in "defining" the acid-base disturbances we will be as scientific as possible, and write:
1. Raised anion gap metabolic acidosis (AG 29. DR 1)
2. Relative respiratory acidosis (expect CO2 = 18 for HCO3- 7)
A differential for each is relatively easy to generate.
1. Raised anion gap metabolic acidosis (AG 29. DR 1)
2. Relative respiratory acidosis (expect CO2 = 18 for HCO3- 7)
You could add heaps more onto each of these, but we would be confident at this stage that we have covered all the major stuff comprehensively. We have also attempted to minimize the words we have used to do this.
Question 2.
Outline 3 management priorities you will act upon in this situation.
Now, this is harder. People tend to hate these "priority" type questions (they also seem to be relatively poorly defined in the new exam compared to the old). But, it's a sick child so we can come up with some priorities easily enough. MAKE SURE YOU NOTE THE STEM - a "distressed mother". This is a clear lead into this question, and managing mum needs to be mentioned!
1. Seizure control: with antiepileptics and glucose correction
2. Treat underlying cause: sepsis, hypoglycaemia. Exclude NAI.
3. Manage mother: (this is the "consultant level trap" in the question) designate staff member to explain and answer questions
You'll note we have stuck two paediatric specific things in there - managing the parents is an essential priority in most paediatric cases. Thinking about neglect and NAI is often another "must mention". We've snuck it in here under our "underlying cause" priority, because it fits. Even though there's nothing specific to suggest NAI in this case, mentioning it is good exam technique and shows consultant level perspective.
Question 3.
Describe three treatments you could administer to terminate the seizure, including the dose appropriate for this patient.
Again, this illustrates things you MUST know for paediatrics - how to calculate a weight and how to calculate appropriate emergency drugs.
So, we would write:
6yo weight = 2x6 + 8 = 20kg
1. Glucose (5ml/kg 10% dextrose) = 100ml 10% dextrose IV bolus
2. Midazolam (0.15mg/kg) = 3mg IV
3. Phenytoin (15-20mk/kg) = 400mg over 30 minutes IVI.
Now, again, there are not many words in our answer, but there is a lot of specific information: THIS child's weight, the weight based dose of drug we are using, the ACTUAL dose of drug we are using and the method of administration. So, remember paeds answers need to be customized to the child that you are treating, and again we wish to reinforce one of the core themes of our course: write as scientifically as possible.
A 6 year old boy presents to your department with the ambulance after a seven minute seizure. He is still fitting when he arrives in resus. His distraught mother accompanies him into the resuscitation room.
His prior vital signs with the ambulance include a temperature of 39.6oC.
Access is obtained and an urgent venous gas is obtained.
pH 7.11
pCO2 26 mmHg
pO2 54 mmHg
HCO3- 7 mmol/L
Na+ 140 mmol/L
Cl- 104 mmol/L
Glucose 1.7 mmol/L
Lactate 10.6 mmol/L
Question 1.
Describe the major acid-base disturbances present and give a differential for each.
When approaching these questions, we would reiterate it is important to be as scientific and concise as possible.
This patient has a profound acidaemia, with a bicarb of 7. There is therefore a metabolic acidosis.
Defining the metabolic acidosis we find an AG = 140 - 7 - 104 = 29. This yields a delta ratio of (29-12)/(24-7) = 17/17 = 1.0. Therefore we have an isolated RAGMA.
We expect our CO2 = 8 + 1.5 x 7 = 18.5. This patient has a higher CO2 and therefore has a relative respiratory acidosis.
Therefore in "defining" the acid-base disturbances we will be as scientific as possible, and write:
1. Raised anion gap metabolic acidosis (AG 29. DR 1)
2. Relative respiratory acidosis (expect CO2 = 18 for HCO3- 7)
A differential for each is relatively easy to generate.
1. Raised anion gap metabolic acidosis (AG 29. DR 1)
- Hyperlactataemia:
- Type A: Seizure and tissue hypoxia, decreased perfusion (eg hypovolaemia)
- Type B1: Sepsis (urine, chest, occult)
- Type B2: occult drug overdose (eg metformin given decreased BSL)
- Type B3: undiagnosed metabolic error (note less likely at 6yo)
- Type A: Seizure and tissue hypoxia, decreased perfusion (eg hypovolaemia)
- Others less likely (DKA - low glucose), renal failure (check renal indices)
2. Relative respiratory acidosis (expect CO2 = 18 for HCO3- 7)
- Primary underventilation due to apnoea during seizure
- Other lung pathology: pneumonia/aspiration
You could add heaps more onto each of these, but we would be confident at this stage that we have covered all the major stuff comprehensively. We have also attempted to minimize the words we have used to do this.
Question 2.
Outline 3 management priorities you will act upon in this situation.
Now, this is harder. People tend to hate these "priority" type questions (they also seem to be relatively poorly defined in the new exam compared to the old). But, it's a sick child so we can come up with some priorities easily enough. MAKE SURE YOU NOTE THE STEM - a "distressed mother". This is a clear lead into this question, and managing mum needs to be mentioned!
1. Seizure control: with antiepileptics and glucose correction
2. Treat underlying cause: sepsis, hypoglycaemia. Exclude NAI.
3. Manage mother: (this is the "consultant level trap" in the question) designate staff member to explain and answer questions
You'll note we have stuck two paediatric specific things in there - managing the parents is an essential priority in most paediatric cases. Thinking about neglect and NAI is often another "must mention". We've snuck it in here under our "underlying cause" priority, because it fits. Even though there's nothing specific to suggest NAI in this case, mentioning it is good exam technique and shows consultant level perspective.
Question 3.
Describe three treatments you could administer to terminate the seizure, including the dose appropriate for this patient.
Again, this illustrates things you MUST know for paediatrics - how to calculate a weight and how to calculate appropriate emergency drugs.
So, we would write:
6yo weight = 2x6 + 8 = 20kg
1. Glucose (5ml/kg 10% dextrose) = 100ml 10% dextrose IV bolus
2. Midazolam (0.15mg/kg) = 3mg IV
3. Phenytoin (15-20mk/kg) = 400mg over 30 minutes IVI.
Now, again, there are not many words in our answer, but there is a lot of specific information: THIS child's weight, the weight based dose of drug we are using, the ACTUAL dose of drug we are using and the method of administration. So, remember paeds answers need to be customized to the child that you are treating, and again we wish to reinforce one of the core themes of our course: write as scientifically as possible.