A 70-year-old male presents to the ED with a 2-week history of increasing dyspnoea, cough with altered sputum and fever. Past history includes chronic obstructive airways disease (COPD), lung cancer seven years ago treated with chemotherapy and radiation therapy with no sign of recurrence since.
Examination findings included RR 30 breaths/min, BP 110/70mmHg, HR 145 bpm, Temp 37.4ºC, anxious and distress but tired and peripherally cold and cyanosed.
CXR shows findings consistent with COPD and right lower lobe infiltrate.
The following arterial blood gas is taken one hour after receiving 2 litres of fluid resuscitation, antibiotics and bi-level non-invasive ventilation (NIV), at FiO2 = 1.0.
|
Parameter |
Patient Value |
Normal Adult Range |
|||
|
FiO2 |
1.0 |
||||
|
pH |
7.16* |
7.35 |
– 7.45 |
||
|
PCO2 |
33 mmHg* (4.3 kPa)* |
35 |
– |
45 (4.6 – 6.0) |
|
|
PO2 |
272 mmHg (38.5 kPa) |
||||
|
Bicarbonate |
11 mmol/L* |
22 |
– |
30 |
|
|
Base Excess |
-17 mmol/L* |
-3 – +3 |
|||
|
Sodium |
138 mmol/L |
135 – 145 |
|||
|
Potassium |
4.3 mmol/L |
3.5 – 5.0 |
|||
|
Chloride |
121 mmol/L* |
95 |
– |
110 |
|
|
Glucose |
13.1 mmol/L* |
3.5 – 7.8 |
|||
|
Lactate |
6.4 mmol/L* |
0.6 – 2.4 |
|||
|
Haemoglobin |
131 g/L* |
135 – 175 |
|||
|
Creatinine |
150 micromol/L* |
70 |
– |
120 |
|
Six hours later the patient remains on NIV, is conscious, reports feeling slightly better, feet remain cyanosed, BP 105/72 mmHg, HR 108 bpm, RR 30 breaths/min, urine output 10 – 20 mL/hr and the following biochemistry profile is obtained:
|
Parameter |
Patient Value |
Normal Adult Range |
||||
|
Sodium |
139 mmol/L |
135 – 145 |
||||
|
Potassium |
5.5 mmol/L* |
3.5 – 5.2 |
||||
|
Chloride |
110 mmol/L |
95 |
– 110 |
|||
|
Bicarbonate |
12 mmol/L* |
22 |
– 32 |
|||
|
Urea |
20.0 mmol/L* |
2.7 – 7.8 |
||||
|
Creatinine |
220 μmol/L* |
70 |
– 120 |
|||
|
Estimated glomerular filtration rate (eGFR) |
25 mL/min/1.73 m2* |
> 90 |
||||
|
Anion gap |
22 mmol/L* |
8 – 18 |
||||
|
Total protein |
57 g/L* |
60 |
– 80 |
|||
|
Albumin |
27 g/L* |
35 |
– 50 |
|||
|
Total bilirubin |
24.9 μmol/L |
< 25 |
||||
|
Alkaline phosphatase (ALP) |
81 IU/L |
30 |
– 110 |
|||
|
Alanine transaminase (ALT) |
6138 IU/L* |
< 65 |
||||
|
Aspartate transaminase (AST) |
10122 IU/L* |
< 50 |
||||
|
g-Glutamyl transferase (GGT) |
88 IU/L |
< 90 |
||||
|
C-reactive protein (CRP) |
22.5 mg/L* |
< 8 |
||||
The patient’s haematology results are as follows:
|
Parameter |
Patient Value |
Normal Adult Range |
|||||||||
|
Haemoglobin |
87 g/L* |
130 – 180 |
|||||||||
|
White cell count |
2.1 x 109/L |
4 – 11 |
|||||||||
|
Platelets |
54 x 109/L |
140 – 440 |
|||||||||
|
International normalised ratio (INR) |
2.4 |
0.8 – 1.2 |
|||||||||
|
Activated partial thromboplastin time (APTT) |
38 sec* |
25 – 35 |
|||||||||
c) What is your interpretation of these findings? (20% marks)
c)
Acute anaemia, acute or chronic leucopaenia, acute or chronic thrombocytopaenia, coagulopathy with raised INR
No unifying diagnosis
Acute drop in haemoglobin over 2 hours is most likely due to haemorrhage or massive fluid infusion. Massive haemolysis is less likely given the bilirubin is not raised
Sepsis most likely cause of leucopaenia, thrombocytopaenia and raised INR
Acute liver failure may explain raised INR
Bone marrow failure would explain leucopaenia and thrombocytopaenia if they are chronic.
Any cause of bone marrow failure also accepted.
This is the third part of this SAQ. Question 23.1 is an ABG interpretation question, and Question 23.2 is more about the differential diagnosis of deranged LFTs.
The following list of differentials can be reproduced from the pancytopenia chapter:
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|
These are all forms of a "unifying diagnosis" which is perhaps not appropriate here. The college answer seems to tolerate an individual list of differentials for each individual blood test abnormality, rather than expecting the candidates to connect the dots and make a diagnosis of haemophagocytic lymphohistiocytosis or some such. However, the trainees might not be aware of this. Some readers of Deranged Physiology have been in correspondence regarding this matter, and their profanity-laced comments suggest that to have a unifying diagnosis for these sorts of SAQs is one of their expectations. When asked "what is your interpretation of the findings", the correct answer should not be "these findings defy interpretation" or "just about anything, or several things, could be the cause".