6.1. This blood gas report was taken from a lady hospitalised for recurrent urinary tract infections. She was transferred to the ICU because of nosocomial pneumonia.
- a) Comment on the acid-base status.
- b) List 2 likely causes of the acid-base derangement in this patient.
6.2. A 40 year old 70 kg male has gram negative sepsis and has developed bilateral pulmonary infiltrates. The following are data from blood gas analysis.
- a) Could this blood gas be consistent with the definition of acute respiratory distress syndrome (ARDS)? Give your reasoning.
- b) What dose of sodium bicarbonate (in mmol) would be required to reverse the metabolic acidosis? Show your calculation method.
6.3. Following laparotomy for haemoperitoneum, a patient is transferred to ICU. Blood biochemistry and arterial blood gas analysis on admission to ICU are as follows:
- a) Describe the acid-base status.
- b) What is the likely cause of this disturbance?
- c) What is the underlying biochemical mechanism?
6.4. A 33 year old female has gram negative bacteraemia and septic shock. The following are data from blood gas analysis.
- a) List the acid-base abnormalities.
Answer and interpretation
6.1. a) Comment on the acid-base status.
- Mixed respiratory and metabolic alkalosis
6.1. b) List 2 likely causes of the acid-base derangement in this patient.
- Respiratory alkalosis from the hyperventilation due to the pneumonia
- Metabolic alkalosis from vomiting or diuretic use.
6.2. a) Could this blood gas be consistent with the definition of acute respiratory distress syndrome (ARDS)? Give your reasoning.
- No. The P/F ratio is 220.
- By definition, the problem would be acute lung injury rather that ARDS at this stage.
6.2. b) What dose of sodium bicarbonate (in mmol) would be required to reverse the metabolic acidosis? Show your calculation method.
- Dose sodium bicarbonate = Wt (kg) x 0.3 x -SBE = 70 x 0.3 x 10 = 210 mmol
6.3. a) Describe the acid-base status.
- Normal anion gap metabolic acidosis with appropriate respiratory compensation
6.3. b) What is the likely cause of this disturbance?
- Resuscitation with large volume saline infusion.
6.3. c) What is the underlying biochemical mechanism?
- ECF dilution by fluid with strong ion difference of zero
6.4. a) List the acid-base abnormalities.
- Lactic acidosis
- Anion gap elevation (37 mEq/L)
- Metabolic alkalosis
- Respiratory alkalosis
- Pass rate: 86.1%
- Highest mark: 9.25
Chris is an Intensivist and ECMO specialist at the Alfred ICU in Melbourne. He is also a Clinical Adjunct Associate Professor at Monash University. He is a co-founder of the Australia and New Zealand Clinician Educator Network (ANZCEN) and is the Lead for the ANZCEN Clinician Educator Incubator programme. He is on the Board of Directors for the Intensive Care Foundation and is a First Part Examiner for the College of Intensive Care Medicine. He is an internationally recognised Clinician Educator with a passion for helping clinicians learn and for improving the clinical performance of individuals and collectives.
After finishing his medical degree at the University of Auckland, he continued post-graduate training in New Zealand as well as Australia’s Northern Territory, Perth and Melbourne. He has completed fellowship training in both intensive care medicine and emergency medicine, as well as post-graduate training in biochemistry, clinical toxicology, clinical epidemiology, and health professional education.
He is actively involved in in using translational simulation to improve patient care and the design of processes and systems at Alfred Health. He coordinates the Alfred ICU’s education and simulation programmes and runs the unit’s education website, INTENSIVE. He created the ‘Critically Ill Airway’ course and teaches on numerous courses around the world. He is one of the founders of the FOAM movement (Free Open-Access Medical education) and is co-creator of litfl.com, the RAGE podcast, the Resuscitology course, and the SMACC conference.
His one great achievement is being the father of three amazing children.
On Twitter, he is @precordialthump.