Lab case 394 Interpretation


 Question 1:

PH = 7.475, that is mild alkalaemia.

pCO2 = 24 mmHg. So, we have respiratory alkalosis.

From the story/ History we can tell that the case is acute.

Regarding compensation for acute respiratory alkalosis. We expect HCO3 to drop by 2 for every 10 pCO2 below 10 (From 40 mmHg).

Accordingly, expected HCO3 =24 – [(40 – 24) x 0.2] = 20.8. HCO3 for this patient is lower than that (17.6 mmol/L). So, we have additional metabolic acidosis.

Next, we will calculate the will calculate the anion gap to figure out what type of metabolic acidosis this patient has.

Anion gap = Na – (Cl + HCO3) = 15.4. Accordingly, this patient has HAGMA.

This patient has combined acute respiratory alkalosis and HAGMA.

Other abnormal findings:

Na = 124 mmol/L, that is moderate hyponatremia. From the story it is acute.

Cl = 91 mmol/L, that is hypochloraemia.

Lactate = 7.6 mmol/L, that is severe hyperlactataemia.

This high lactate level is the cause of HAGMA.

This patient had seizure (The cause of high lactate). Seizure was caused by acute hyponatraemia. Low Na level was due to inappropriate ADH secretion caused by COVID. (Cytokine mediated lung injury “IL6” via hypoxic pulmonary vasoconstriction leads to stimulation of non-somatic release of ADH).

 Question 2:

Neurological emergencies (Seizures, confusion or obtundation) are indications of emergency department treatment with 3% hypertonic saline. In the absence of any of these signs, the emergency department management consists of fluid restriction and investigation for the cause.

 Question 3:

In the presence of seizure, we should administer 100mL of 3% saline over 10 minutes or until seizure stops. This will raise serum Na by 2-3mmol/L.

In other cases, administer 3% saline at rate of 1 ml/Kg/hr.

Easy way to remember is: 3% saline, 3 ml/kg over 30 minutes. (Is an alternative way).