From the Guidelines
A CO2 level of 18 on a Comprehensive Metabolic Panel (CMP) is indicative of metabolic acidosis, which can be a life-threatening condition if left untreated. This finding suggests that the blood is more acidic than normal, as bicarbonate helps maintain proper blood pH 1. Normal CO2 levels typically range from 23-29 mEq/L, so a value of 18 is below the reference range. According to the BTS guideline for oxygen use in adults in healthcare and emergency settings, carbon dioxide levels in the blood are controlled by chemical sensors, and increased levels of carbon dioxide will stimulate ventilation 1.
Some possible causes of low CO2 levels include:
- Kidney problems
- Severe diarrhea
- Diabetic ketoacidosis
- Lactic acidosis
- Certain medications
It is essential to discuss this result with a healthcare provider promptly, as they may need to perform additional tests to determine the underlying cause 1. Symptoms of metabolic acidosis can include:
- Rapid breathing
- Fatigue
- Confusion
- In severe cases, shock
Treatment depends on identifying and addressing the root cause, which might involve IV fluids, sodium bicarbonate supplementation, or management of the underlying condition 1. It is crucial not to attempt to self-treat this condition, as proper medical evaluation is essential to prevent morbidity and mortality. The BTS guideline highlights the importance of safe elimination of carbon dioxide to maintain pH, and in some cases, targeted lower concentration oxygen therapy may be necessary to avoid oxygen-induced hypercapnia 1.
From the Research
CMP Results
- A CMP (Comprehensive Metabolic Panel) showing CO2 levels of 18 can indicate metabolic acidosis, a condition where the blood is too acidic 2, 3, 4.
- Metabolic acidosis occurs when the body produces too much acid or when the kidneys are not removing enough acid from the body 4.
- The normal range for CO2 levels in the blood is 23-29 mmol/L, so a level of 18 is below normal 2, 3.
Possible Causes
- Metabolic acidosis can be caused by a variety of factors, including:
- Diarrhea or renal proximal tubular acidosis, which can lead to a loss of bicarbonate in the body 2, 4.
- Diabetic ketoacidosis, lactic acidosis, septic shock, intraoperative metabolic acidosis, or cardiac arrest, which can all lead to an accumulation of acid in the body 4.
- Chronic kidney disease, which can lead to an accumulation of acid in the body due to decreased kidney function 5, 6.
Treatment
- Treatment for metabolic acidosis typically involves addressing the underlying cause of the condition 2, 3, 4.
- Sodium bicarbonate therapy may be used to treat metabolic acidosis, particularly in patients with severe acidosis or those with chronic kidney disease 2, 3, 5, 4.
- Dietary changes, such as increasing intake of fruits and vegetables, may also be recommended to help reduce acid production in the body 6.