A 56 year old gentleman with chronic obstructive pulmonary disease returns to the intensive care unit following a left pneumonectomy for a squamous cell carcinoma. There is no other past medical history.
Examination reveals that he is fully alert, comfortable, with a thoracic epidural catheter in situ, respiratory rate 16 bpm, HR 60 bpm, BP 100/80 mmHg and warm peripheries. Auscultation reveals reduced breath sounds over the left lung field. There is no bubbling and minimal drainage from the left intercostal catheter.
His arterial blood gas on return from theatre reveals:
FiO2 0.5
pH 7.27
Pa CO2 50 mmHg
Pa O2 90 mmHg
HCO3- 22mmol/L
BE -4.7 mEq/L
1. What explanations would you give for the abnormalities in this arterial blood gas report?
Disclaimer: the viva stem above may be an original CICM stem, acquired from their publicly available past papers. Or, perhaps it is a slightly altered version of the original CICM stem. Or, it is a completely original viva stem, concocted by the monstrously amoral author of Deranged Physiology for nothing more than his own personal amusement. In either case, because the college do not make the main viva text or marking criteria available, almost everything here has been confabulated. It might sound like a plausible viva and it could be used for the purpose of practice, but all should be aware that it does not represent the "true" canonical CICM viva station.