A 22-year-old male climbed to a height of 3574 m above sea level. On arrival at this altitude he complained of chest tightness, breathlessness, tiredness and had an altered sensorium. He was evacuated to a nearby medical facility which was situated at an altitude of 700 m. His ECG was unremarkable and chest X-ray showed bilateral infiltrates.
The following arterial blood gas was taken at the medical facility:
Parameter |
Patient Value |
Adult Normal Range |
Barometric pressure |
701 mmHg (94 kPa) |
|
FiO2 |
0.21 |
|
pH |
7.30* |
7.35 – 7.45 |
pO2 |
57.0 mmHg (7.6 kPa) |
|
pCO2 |
32.0 mmHg (4.3 kPa)* |
35.0 – 45.0 (4.6 – 6.0) |
SpO2 |
85% |
|
Bicarbonate |
15.0 mmol/L* |
22.0 – 26.0 |
Lactate |
6.0 mmol/L* |
0.5 – 1.6 |
Sodium |
140 mmol/L |
135 – 145 |
Potassium |
4.1 mmol/L |
3.5 – 5.0 |
Chloride |
102 mmol/L |
95 – 105 |
Glucose |
5.6 mmol/L |
3.5 – 6.0 |
a) Interpret the blood gas. (20% marks)
b) What is the most likely diagnosis? (20% marks)
c) What treatment would you institute in this patient? (60% marks)
General (2)
High altitude pulmonary oedema (2)
High altitude cerebral oedema (2)
First, let's go though the ABG:
In short, this is a straightforward high anion gap metabolic acidosis with adequate respiratory compensation.
Now, for 2 marks, "what is the most likely diagnosis?"
The clinical features are:
Combine this with the story of high altitute, and HACE/HAPE become the inevitable conclusions. The college does not give any extensive explanations of what these are, and the trainees were not expected to expand on their pathophysiology or produce a list of differentials
Management:
Mehta, S. R., A. Chawla, and A. S. Kashyap. "Acute mountain sickness, high altitude cerebral oedema, high altitude pulmonary oedema: The current concepts." Medical journal, Armed Forces India 64.2 (2008): 149.
Basnyat, Buddha, and David R. Murdoch. "High-altitude illness." The Lancet 361.9373 (2003): 1967-1974.
Hackett, Peter H., and Robert C. Roach. "High-altitude illness." New England journal of medicine 345.2 (2001): 107-114.
Bhagi, Shuchi, Swati Srivastava, and Shashi Bala Singh. "High-altitude pulmonary edema." Journal of occupational health (2014): 13-0256.
Basnyat, Buddha. "High altitude cerebral and pulmonary edema." Travel medicine and infectious disease 3.4 (2005): 199-211.
Stuber, Thomas, and Yves Allemann. "High altitude illness-pathogenesis and treatment." SCHWEIZERISCHE ZEITSCHRIFT FUR SPORTMEDIZIN UND SPORTTRAUMATOLOGIE 53.2 (2005): 88.