Your doctor may perform a blood gas analysis if you show symptoms of imbalances in oxygen, carbon dioxide, or pH levels, such as confusion or difficulty breathing. This test measures the partial levels of those substances using a small blood sample. From this information, your doctor can tell if your lungs carry oxygen in the blood and eliminate carbon dioxide efficiently. The values can also indicate certain conditions, such as heart or kidney failure, drug overdose, or uncontrolled diabetes. Your doctor is the person who can best interpret the test results, but you too can get some clues by analyzing them. Interpret the test results by reading them carefully and considering other information.
Steps
Part 1 of 2: Read Test Results Carefully
Step 1. Review the results with your doctor
The best way to interpret blood gas values is to speak to your doctor. He is able to understand information and results better than anyone else. Doing an evaluation yourself can lead to a misdiagnosis or complications from the treatments you choose. Ask the doctor to answer all your questions about the individual levels and what they suggest.
- Ask your doctor to explain all values to you individually, explaining what is being measured and what the specific results mean.
- Ask your doctor to compare the old values with the new ones, in order to better judge your health status.
Step 2. Observe the pH value
This number measures the amount of hydrogen ions in the blood and can indicate conditions such as chronic obstructive pulmonary disease (COPD), asthma, pregnancy, diabetic ketoacidosis (CAD), lung disease, liver disease, or drug use. The range of normal values for pH is 7.35 to 7.45.
- If the pH is below 7.35, you have acidic blood, which can be caused by airway obstructions, COPD, asthma, sleep breathing disorders, and neuromuscular conditions.
- If the pH exceeds 7.45, you may be suffering from alkalosis, a potential symptom of central nervous system stimulation, kidney disease, severe anemia, drug use, or pregnancy.
Step 3. Check the levels of bicarbonate, or HCO3.
Your kidneys produce bicarbonate and help regulate the normal pH of the blood. Normal bicarbonate levels are between 22 and 26 milliEquivalents per liter (mEq / L). An imbalance can indicate conditions such as respiratory or liver failure and anorexia.
- A level of HCO3 less than 24 mEq / L indicates metabolic acidosis. It can be the result of conditions such as diarrhea, liver failure and kidney disease.
- A level of HCO3 above 26 mEq / L indicates metabolic alkalosis. It can be the result of dehydration, vomiting and anorexia.
Step 4. Review the PaCO value2.
The partial pressure of carbon dioxide measures the amount of this gas in the blood. The normal level is between 38 and 45 mmHg. An imbalance can indicate shock, kidney failure, or chronic vomiting.
- If the level of PaCO2 is less than 35 mmHg you suffer from respiratory alkalosis. This indicates that the carbon dioxide level in the blood is too low and can be a symptom of kidney failure, shock, diabetic ketoacidosis, hyperventilation, pain or anxiety.
- If the level of PaCO2 exceed 45 mmHg you suffer from respiratory acidosis. This means that the carbon dioxide level in the blood is too high and can be a symptom of chronic vomiting, potassium deficiency, COPD or pneumonia.
Step 5. Evaluate the value of PaO2.
The partial pressure of oxygen measures the efficiency of the transfer of this gas from the lungs to the blood. The normal level is between 75 and 100 mmHg. An imbalance can indicate anemia, carbon monoxide poisoning, or sickle cell anemia.
Step 6. Note the oxygen saturation
The ability of hemoglobin to carry oxygen to red blood cells is called oxygen saturation. The normal level is between 94 and 100%. An imbalance can indicate the following problems:
- Anemia
- Asthma
- Congenital heart defects
- COPD or emphysema
- Stretches of the abdominal muscles
- Lung collapse
- Pulmonary edema or embolism
- Sleep apnea
Part 2 of 2: Consider Other Information
Step 1. Consider medications and drugs
Certain factors, such as your health, the drug therapies you follow, and the environment you live in can affect the results of the blood gas analysis. If you use any of the following, consider that they can alter the test values:
- Anticoagulants, including aspirin
- Illicit drugs
- Tobacco or passive smoking
- Tetracycline (antibiotic)
- Steroids
- Diuretics
Step 2. Consider your geographic location
The amount of oxygen in the air decreases with height above sea level and can affect the results of the blood gas analysis. If you live at an altitude of 900 meters or higher, consider this factor when interpreting the test. Ask your doctor to make a correlation between the partial pressure of oxygen and the area you live in, or consider that normal saturation levels drop to 80-90% between 3000 and 4500 meters.
Respiratory alkalosis is often associated with mountain travel. Hyperventilation in particular is very common when the ascent is too rapid and not enough time has been devoted to acclimatization
Step 3. Think about your current health condition
Many diseases, from liver failure to fever, can alter the results of the blood gas analysis. Consider these factors when interpreting the test and discuss them with your doctor. The following conditions can create imbalances in normal blood gas levels:
- Fever
- Hyperventilation
- Overdose of drugs
- Head or neck injuries
- Respiratory disorders, such as asthma or COPD
- Congestive heart failure
- Kidney failure
- Diabetes
- Blood disorders, such as haemophilia
Step 4. Compare the test results with previous exams
If this is not the first time you have a blood gas test, compare the results. This way you can see differences that suggest the appearance of a new problem or the improvement of an existing one. Remember to discuss the comparison with your doctor as well.
