Lab Case 337 Interpretation

39 year old IDDM, presents with a 1 day history of vomiting. The patient has been on an alcohol binge and non-compliant with his insulin.


pH 7.50                                            Na 141mmol/l

pCO2 39mmHg                                K 4.1mmol/l

HCO3 30mmol/l                                Cl 82mmol/l

B/E 7                                                 Cr 136mmom/l

Lactate 3.2                                        BSL 22mmol/l

Ketones 7.8 mmol/l

  1. Describe and Interpret the VBG
  2. How would you manage this patient?


Metabolic alkalosis pH 7.50 HCO3 30mmol/l

Compensation- Expected PCO2 = 0.7 x HCO3 + 20 = 41

Raised ketones and lactate

AG = Na- (HCO3 + Cl) = 29

Low chloride, raised Cr and BSL

The above VBG shows a mixed acid base disturbance, with a primary compensated hypochloraemic metabolic alkalosis and an underlying HAGMA. There is a mildly elevated creatinine and a markedly raised BSL and ketones and a moderately raised lactate. In this clinical context the metabolic alkalosis is likely due to HCL loss from the vomiting.  The patients vomiting caused by alcohol ingestion and high ketones.  Other causes for the vomiting should be considered – infection, head injury. Renal losses and HCO3 excess as the cause of the metabolic alkalosis is less likely in this case.

The underlying HAGMA will be due to a ketosis and lactate. The ketosis in this case can be due to DKA, starvation ketosis or alcohol ketosis. The lactic acidosis is likely due to hypovolaemia, as well as alcohol intoxication.

Management of this patient should involve

  • Fluids – normal saline. Metabolic alkalosis in this case should be chloride responsive. By replacing fluids and stopping the vomiting the alkalosis should resolve. 1 L normal saline stat followed by DKA protocol fluids. Maintain B MAP 60mmHg, and monitor input and output aiming for U/O 0.5ml/kg-1ml/kg/hr
  • Antiemetics to stop the vomiting
  • Look for and treat possible other underlying causes of the vomiting and DKA
  • Treat underlying DKA – start insulin infusion – monitoring electrolytes and ketones
  • Admission for on going Mx and education