From the Guidelines
Base deficit is a critical laboratory measurement that indicates the amount of acid in the blood beyond what is normal, with a normal range of -2 to +2 mEq/L, and is used to guide resuscitation efforts in trauma patients, as evidenced by the most recent study in 2023 1.
Definition and Calculation
Base deficit represents how much base would be needed to restore the blood's pH to normal and is calculated during arterial blood gas analysis. It helps clinicians assess the severity of acidosis, particularly in conditions like shock, sepsis, or trauma.
Clinical Significance
The measurement reflects the body's buffer system status and can indicate tissue hypoperfusion, as inadequate oxygen delivery to tissues leads to anaerobic metabolism and lactic acid production.
Prognostic Value
The initial base deficit is a potent independent predictor of mortality in patients with traumatic haemorrhagic shock, as shown in a study published in 2023 1. Serial measurements of base deficit can help track a patient's response to treatment and overall clinical trajectory.
Stratification
Base deficit values can be stratified into three categories: mild (-3 to -5 mEq/l), moderate (-6 to -9 mEq/l), and severe (less than -10 mEq/l), which can help establish a correlation between the admission base deficit and transfusion requirements within the first 24 hours and the risk of post-traumatic organ failure or death, as demonstrated in a study published in 2007 1.
Comparison with Lactate Levels
While both blood lactate levels and base deficits are well correlated with shock and resuscitation, these two variables do not strictly correlate with each other in severely injured patients, and lactate levels more specifically reflect the degree of tissue hypoperfusion, as noted in the 2023 study 1.
From the Research
Definition of Base Deficit
- Base deficit is a measure of the amount of base (such as bicarbonate) that is lacking in the blood, typically measured in millimoles per liter (mmol/L) or milliequivalents per liter (mEq/L) 2, 3.
- It is an indicator of metabolic acidosis, a condition in which the blood is too acidic due to an imbalance in the body's acid-base balance.
Calculation of Base Deficit
- The base deficit is calculated using the arterial blood gas (ABG) results, which measure the pH, partial pressure of carbon dioxide (PaCO2), and bicarbonate (HCO3-) levels in the blood 4.
- The base deficit is typically calculated using the following formula: Base Deficit = (Normal HCO3- - Actual HCO3-) x Body Weight (in kg) 5.
Clinical Significance of Base Deficit
- A base deficit indicates that the body has lost too much base, which can occur due to various conditions such as diarrhea, vomiting, or certain medications 2, 3.
- A severe base deficit can lead to serious complications, including cardiac arrhythmias, decreased cardiac output, and impaired oxygen delivery to tissues 2, 3.
- Treatment of base deficit typically involves correcting the underlying cause of the metabolic acidosis, as well as administering base (such as sodium bicarbonate) to help restore the body's acid-base balance 2, 3, 5.