Arterial blood gas analysis

Arterial blood gas (ABG) analysis is a valuable tool Aurora doctors use to check for metabolic disorders, lung health and sometimes serious health situations such as sepsis or diabetic ketoacidosis.

During an ABG analysis, blood is taken from an artery and tested to see how much oxygen and carbon dioxide is in it. They can also check acid-base balance (pH levels) and other gases that also provide insights into ventilation and oxygenation.

The insights from an arterial blood gas test help your Aurora doctor to diagnose and manage conditions that affect your metabolism, heart and lungs.

Clinical significance of ABG parameters in diagnoses

Arterial blood gas tests are often used in emergency department situations to uncover several life-threatening conditions, including:

• Acute respiratory distress syndrome (ARDS): A life-threatening lung injury that causes dangerously low oxygen levels in your blood.
• Asthma attack: A sudden worsening of asthma symptoms caused by the tightening of muscles around your airways.
• Cardiac arrest: This happens when your heart suddenly stops beating. It can happen to individuals who may or may not have heart disease and requires immediate medical attention.
• Diabetes-related ketoacidosis (DKA): A life-threatening complication that affects people with diabetes, mainly type 1 diabetes.
• Renal tubular acidosis (RTA): This condition happens when your kidneys don’t remove acids from your blood into your urine as they should, causing your blood to become acidic.
• Septic shock: A life-threatening condition that happens when your blood pressure drops to a dangerously low level after an infection.
• Severe sepsis: Sepsis is a medical emergency caused by your body's response to an infection and can be life-threatening.

Understanding pH levels in an ABG analysis

A primary measurement of the ABG analysis process is evaluating pH levels in the blood. Your body has mechanisms in place to maintain pH within a specific range and keep it from being too acidic or alkaline.

Acids and bases play a crucial role in how your body functions. Your body compensates for changes in acid levels by breathing and with hemoglobin, a protein in red blood cells. Changes to oxygen and carbon dioxide, along with hemoglobin, are reflected in arterial blood gas test results.

Assessing respiratory status

Breathing not only provides oxygen to your cells but it also eliminates carbon dioxide, a waste product of your metabolism (how your body turns food into energy).

The body might adjust the respiratory rate in response to changes in pH levels. For instance, metabolic acidosis could lead to increased breathing to expel more carbon dioxide and raise the blood pH levels.

Interpreting oxygenation levels

Oxygenation is critical for cellular functions. In ABG Interpretation guidelines, two key parameters assess oxygenation.

• Oxygen saturation: This is how much oxygen is attached to hemoglobin.
• Partial pressure of oxygen: This reveals the amount of oxygen that is in your blood. It's a direct measurement of how well the lungs deliver oxygen to the blood.

Analyzing metabolic imbalances in arterial blood gases

While the respiratory system can adjust to maintain pH, the metabolic process and kidneys also play a crucial role. An arterial blood gas test checks for bicarbonate levels in the blood. Low bicarbonate levels might suggest metabolic acidosis, a condition where the body either produces too much acid or fails to excrete it.

Bicarbonate is a byproduct of your body’s metabolism. Your blood carries bicarbonate to your lungs, where it’s exhaled as carbon dioxide. Your kidneys also help remove bicarbonate from your body.

When to get an arterial blood gas test

If you have COPD (chronic obstructive pulmonary disease) or asthma, your Aurora doctor may regularly order an arterial blood gas test to evaluate the effectiveness of treatment or to check for changes in your blood gases. If you have symptoms or a chronic lung condition, schedule an appointment with your doctor.