CICM SAQ 2012.2 Q14
Questions
Critically evaluate the role of the following investigations in the critically ill patient:
1. Serum ammonia
2. B-type natriuretic peptide (BNP)
Answers
Answer and interpretation
1. Serum ammonia
- Used as an indicator of hepatic encephalopathy
- Normal values do not rule out encephalopathy – therefore of limited utility in patients with known chronic liver disease
- Not useful as a monitor during therapy
- Very high levels may indicate cerebral herniation
- May be useful to indicate undiagnosed cirrhosis in patients presenting with altered mental status
- May also be elevated in: TPN, GI Bleed and steroid use, portosytemic shunts and inborn errors of metabolism.
2. B-type natriuretic peptide (BNP)
- Released from cardiac cells in response to ventricular wall distension
- Elevated in heart failure
- Can be used as a diagnostic marker in patients presenting with dyspnoea to emergency department, and can be useful prognostically and to guide therapy in heart failure
- May be elevated in many other conditions in critical care, including sepsis, acute lung injury, PE and intracranial bleed
- Interpretation of BNP in ICU patients is therefore complex and while it may have a role in prognosis and response to therapy in future its current place is unclear.
- Pass rate: 42%
- Highest mark: 9.0
Examination Library
CICM
Chris is an Intensivist and ECMO specialist at The Alfred ICU, where he is Deputy Director (Education). He is a Clinical Adjunct Associate Professor at Monash University, the Lead for the Clinician Educator Incubator programme, and a CICM First Part Examiner.
He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives. He was one of the founders of the FOAM movement (Free Open-Access Medical education) has been recognised for his contributions to education with awards from ANZICS, ANZAHPE, and ACEM.
His one great achievement is being the father of three amazing children.
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