Question

Daniel Purcel was diagnosed with type 1 diabetes mellitus when he was 12 years old. He is now a nursing student. He has managed to control his diabetes throughout school. However, when he began his clinicals, his regular schedule of meals and insulin injections was completely disrupted. One morning, Daniel completely forgot to take his insulin. At 7am he drank orange juice and ate two doughnuts. At 8am he drank more juice because he was very thirsty. He mentioned to a fellow student that he felt confused, weak, and that his heart was racing. At 9:06 am, he fell unconscious. He was transferred immediately to the emergency room, where the following information was obtained:

Blood pressure: 90/40
Pulse: 130, regular, strong
Respirations: 32, regular rhythm, deep, labored (“Kussmaul”) Plasma glucose: 560 mg/dL (normal fasting 70-110 mg/dL) Plasma HCO3-: 8 mEq/L (normal 24 mEq/L)
Plasma ketones: ++ (normal none)
Arterial PO2: 112 mmHg (normal 100 mmHg)
Arterial PCO2: 20 mmHg (normal 40 mmHg)
Arterial pH: 7.22

The physician determined that Daniel was in diabetic ketoacidosis. He was given an intravenous infusion of isotonic saline and insulin. Later, after his blood glucose had decreased to 175 mg/dL, glucose was added to the infusion. Daniel stayed in the hospital overnight. By the next morning, his blood glucose, electrolytes, and blood gas values were normal.

Questions:

18.Which acid-base disorder did Daniel have? What caused it? Why did he present with Kussmaul respirations? Explain these all in the context of the laboratory test results.

19.How did Daniel’s failure to take insulin cause this acid-base disorder?

20.Explain Daniel’s thirst, low blood pressure, tachycardia, confusion, and weakness.

21.Explain the basis for the treatments provided (saline, insulin, and glucose).

Answer 1

18. The acid- base disorder in which the Daniel have is metabolic acidosis

This is due to the increased production of acidic substances like ketone bodies. This occurs most often in patients with uncontrolled type 1 diabetes. So it is called as diabetic ketoacidosis or DKA. The overproduction of beta- hydroxybutyric acid and acetoacetic acid causes acidosis in DKA. This also leads to the dissociation of these two keto acids and thereby excess hydrogen ions binds to the bicarbonate, resulting in decreased serum bicarbonate levels.

Kussmauls breathing is the deep, laboured breathing pattern. It is a respiratory compensatory mechanism of the body associated with metabolic acidosis. It is a method of hyperventilation. And this reduces the carbon dioxide level in the blood by increasing the rate and depth of respiration.

Normal value of HCO3 in blood = 23-30mEq/L

And pH= 7.35-7.45

But in this patient case the bicarbonate level is 8 mEq/ L and pH is 7 22, that represents the patient is in severe ketoacidosis.

19) Glucose is used as a fuel source in the cellular metabolism. Insulin is used reduce blood glucose level and makes the glucose available for cellular metabolism.

When the patient forgot to take the insulin, then the cells didn't get enough blood glucose. So the patient start producing glucose from fat cells causes increase in ketone bodies resulting in keto acidosis.

21) the treatment of DKA is

1. Fluid therapy : to restore the lost body fluids through excess urination
2. Electrolyte replacement by saline : especially sodium replacement
3. Insulin therapy- to make the blood glucose level to normal level