At 7pm on a Tuesday evening, the medical registrar calls you asking for 'advice only'.
He has admitted a 62 year old builder through casualty with a two day history of vomiting. He has a background of ischaemic heart disease, atrial fibrillation for which he is taking digoxin and warfarin, and peptic ulcer disease. His other medications comprise furosemide (40mg daily), amlodipine (5mg daily), simvastatin (40mg daily) and omeprazole (20mg daily). He drinks 3 to 5 pints of stout per day.
The registrar's main concern is this man's metabolic profile:
Na 120
K 1.6
Mg 0.51
Cl 56
Ur 21
Cr 143
pH 7.62
PCO2 5.8
HCO3 49
BE +23
Clinically, you are told he is in atrial fibrillation with a ventricular rate of 130 bpm, has a blood pressure of 122/60 (falling to 108/52 on standing) and "looks dry".
The main concern of the medical registrar is that, with such severe alkalosis, he may be "missing something" aetiological, such as a "primary renal problem". You, however, take the opportunity to engage with him more broadly on this gentleman's management.
Questions:
1) What mechanisms underlie the initiation and maintenance of alkalosis in this setting? Would you suggest any other investigations to the medical registrar?
2) How would you advise him to manage the metabolic disturbance – and with what urgency? What advice would you give for further monitoring overnight?
Thanks to Mr Peanut for contributing this case
