Case in the Spotlight 17 - Answer and Discussion
30 yo Diabetic. H/O chronic pancreatitis. FiO2 = 0.4 (40%)
Results
Sodium 113 L mmol/L (134-146)
Potassium 4.2 mmol/L (3.4-5.0)
Chloride 80 mmol/L (98-108)
Bicarbonate 12 L mmol/L (22-32)
Urea 6.2 mmol/L (3.0-8.0)
Creatinine 75 umol/L (60-110)
eGFR > 90 mL/min/1.73m^2 (> 60)
Ketones neg
Lactate 5.0 mmol/L (< 1.5)
Glucose 65 H mmol/L (3.0-5.4)
Additional Information:
Lipase 8 U/L (< 60)
Blood gases
pH 7.25 L (7.32-7.43)
pCO2 30 L mmHg (37-50)
pO2 55 H mmHg (36-44)
Bicarbonate 13 L mmol/L (22-28)
Base excess -13 L mmol/L (-3-3)
O2 Sat . 83 H % (70-80)
Describe the acid base disturbance
Acidosis – 7.25
CO2 = low = equals metabolic acidosis
HCO3 = low = metabolic acidosis
CO2 predicted if compensation = 8 + 1.5 x HCO3 = 8 + 18 = 26 so the CO2 is slightly higher than would be expected, so partial compensation
What is the anion gap?
(Na + K) – (HCO3 +Cl)
113 + 4 – (13+ 80) = 117 – 93 = 26 = raised anion gap metabolic acidosis
Although high lactate and ketones not detected, DKA is still possible. Look for causes of shock and hypoxia with the raised lactate, e.g sepsis, pneumonia.
What is the A-a gradient?
Predicted alveolar O2 = 0.4x (760 - 47) – 1.25 x CO2
= 300 approx – (1.25 x 30) = 260 approx
Therefore A-a gradient = approx. 200, so significant
Other abnormalities?
Hyponatraemia (109) Corrected Na = Na + (Glucose -5)/3
= 113 + 60/3 = 133 which is slightly low
What is your clinical interpretation, and main management priorities?
Likely diabetic ketoacidosis
Given slightly high CO2, and raised A-a gradient, the respiratory function needs careful assessment, as there may be an infectious precipitant, aspiration, altered conscious state, fatigue.
Careful monitoring and treatment re fluid replacement, K+ replacement, Na, and BSL corrected slowly, with treatment of co-morbidities. Early senior input re safe admission e.g HDU