August 14, 2022

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How does diabetic ketoacidosis affect arterial blood gas?

Diabetic ketoacidosis (DKA) is a potentially serious complication of diabetes that can cause a range of symptoms. Doctors can use various lab tests to confirm a diagnosis of DKA. These include arterial blood gas (ABG) tests, which measure different components of the blood.

DKA is a potentially life threatening complication of diabetes. It occurs when the body is unable to utilize sugars and instead begins to break down fats for energy. This releases ketones into the blood, which turns it acidic. An ABG, also known as a blood gas analysis, is a test that measures the pH of blood and can help with the diagnosis of metabolic conditions.

In this article, we discuss how DKA can affect an ABG, what ABG ranges indicate DKA, and how to prevent this complication of diabetes.

DKA is a serious complication that can develop in people with diabetes. The condition occurs when the body is unable to use insulin or does not have enough of this hormone to turn blood sugar into energy. If this occurs, the liver turns fat into needed energy, which releases ketones into the bloodstream.

When ketone levels become too high, this causes the blood to become acidic. A change in the acidity of the blood can become life threatening. The American Diabetes Association states that if DKA is severe enough, it can lead to a diabetic coma or death. Although it can occur in people with type 2 diabetes, DKA is more likely to affect those with type 1 diabetes.

In many cases, DKA develops slowly. People may start to notice various symptoms, including:

An arterial blood gas (ABG) test is a type of blood test that measures various components of the blood, such as:

  • oxygen
  • carbon dioxide
  • pH
  • bicarbonate

A healthcare professional will draw blood from an artery, often in the wrist, and run it through an analyzer. Various medical conditions can cause ABG values to fall outside the normal range.

Normal ABG values are as follows:

  • pH: 7.35–7.45
  • Oxygen level (PaO2): 75–100 millimeters of mercury (mm Hg)
  • Carbon dioxide level (PaCO2): 35–45 mm Hg
  • Bicarbonate (HCO3): 22–26 milliequivalents per liter (mEq/l)

Typically, blood maintains a pH value of 7.35–7.45. The balance between alkalinity and acidity, known as the acid-base balance, can become disrupted for many reasons.

When someone develops DKA, the ketones that enter the bloodstream disrupt the acid-base balance, and the blood becomes more acidic. This is because ketoacidosis increases the production of ketones, which, in turn, increase the anion gap. This term refers to the difference between cations, which are positively charged ions, and anions, which are negatively charged ions.

Health experts may use equations, such as the Henderson-Hasselbalch equation and the Lewis model interpretation of biological acidosis, to determine whether the blood is acidic. They will consider it acidic if it has a high concentration of positive hydrogen ions and a low concentration of negative bicarbonate ions.

An ABG test can also measure the partial pressure of carbon dioxide (PaCO2). This measure of carbon dioxide in the blood can serve as a marker of ventilation. Acidosis usually generates a respiratory response. A reduction in bicarbonate and pH may result in hyperventilation and a decrease in carbon dioxide to try to prevent a further fall in pH. As such, an ABG result of a low pH and PaCO2 indicates metabolic acidosis, such as DKA.

Certain values outside of the normal ranges may indicate DKA. Typically, an arterial blood pH value of less than 7.35 suggests DKA. Additionally, a bicarbonate level equal to or less than 18 millimoles per liter (mmol/l) and an anion gap of more than 10 mmol/l indicate DKA.

Doctors classify DKA as mild, moderate, or severe. In addition to the symptoms present, the arterial pH at diagnosis determines the severity of this condition.

The chart below displays the criteria for a DKA diagnosis and the different levels of severity.

Usually, the worse the acidosis, the more severe the symptoms that develop. For example, when the pH of the blood becomes significantly acidic, dropping below 7, the condition becomes life threatening.

Diabetes can lead to DKA when blood sugar levels become very high due to an insulin deficiency. This low level of insulin causes physiological changes, including the breakdown of triglycerides and the release of free fatty acids. The liver converts the fatty acids into ketones and releases them into the circulation, where bodily tissues can use them as fuel.

The American Diabetes Association notes that people with diabetes can develop DKA for a few reasons, including:

  • Not enough insulin: Not having enough insulin in the body may occur if someone misses their insulin dose, administers the wrong dose, or has faulty equipment, such as a clogged insulin pump.
  • Not eating enough: If a person loses their appetite or misses a meal, this can result in high ketone levels.
  • Insulin reaction when sleeping: Some people may also develop ketones overnight as they sleep. This typically occurs due to a reaction to insulin.

The Centers for Disease Control and Prevention (CDC) note other possible causes, such as:

As DKA can become life threatening, it is essential to try to prevent the condition. The CDC explains that people can reduce their risk of DKA by:

  • monitoring their blood sugar levels frequently, especially when sick
  • taking medications, such as insulin, according to the prescription
  • maintaining stable blood sugar levels in the targeted range as much as possible
  • talking with a healthcare professional if blood sugar levels or insulin levels fluctuate significantly overnight
  • working with a doctor or diabetes educator to learn how to adjust insulin levels based on activity levels and food intake

Diabetic ketoacidosis occurs when insufficient insulin results in blood sugar levels becoming too high. Without sufficient insulin, the body is unable to use blood sugar for energy. Instead, it converts fats into ketones, which turns the blood acidic.

Arterial blood gas is a test that measures different components of the blood. DKA can affect ABG ranges by affecting the acid-base balance of the blood. It is essential that a person tries to prevent DKA and undergoes prompt treatment if they receive a diagnosis. DKA can become life threatening without proper treatment.

https://www.medicalnewstoday.com/articles/diabetic-ketoacidosis-arterial-blood-gas