Medical records are full of diagnostic data accompanied by abbreviations that do not make a lot of sense. One type of laboratory value is the ABG (Arterial Blood Gas). They list multiple values that must be read together to come to a diagnostic viewpoint concerning the patients respiratory status and acid abase balance (metabolic status). Values listed are;
- pH – This value is indicative of the acid base balance of the blood stream. Normal values are 7.35-7.45. Any variation in these values requires adjustment in both ventilation and medications to keep the value within normal limits.
- PCO2 – This value is called the partial pressure of CO2 (carbon dioxide) that is saturated in the blood. It reflects the actual CO2 level in the blood stream. CO2 is the best indicator of how well a patient is ventilating (breathing) and the status of gas exchange in the body. CO2 also is the main value which auto-regulates the blood vessels. This means that blood vessels expand and contract in response to CO2 levels in the blood to alter how much flow goes to different areas of the body.
- PO2 – This value reflects the partial pressure of oxygen saturated in the blood stream. Also a good indicator of how well the patient is ventilating and the status of gas exchange in the body.
- Bicarbonate – Bicarbonate ions and carbonic ions are constantly being produced by the body to maintain the acid base balance. They maintain the balance by keeping a 20:1 ratio thereby maintaining a pH of 7.35-7.45.
- BE (base excess) – This value reflects the amount of acid required to restore the body to a normal pH at a CO2 level of 40 mmHG. It increases in metabolic alkalosis and decreases in metabolic acidosis.
- Sat – This is the saturation of oxygen. It indicates how much oxygen is being carried by each red blood cell.
All of these values come together to be analyzed to assess the patients status. It is very complicated and takes much clinical experience to interpret these values correctly. A legal nurse consultant experience in arterial blood gas interpretation can assist you with understanding what the values mean, if the correct diagnosis was made and if the correct treatment was instituted.
