From the Guidelines
Base deficit on an arterial blood gas (ABG) is a critical parameter that indicates the amount of acid that would be needed to normalize the blood pH to 7.4 at normal carbon dioxide levels, and it is a potent independent predictor of mortality in patients with traumatic-hemorrhagic shock. A positive base deficit (or negative base excess) suggests metabolic acidosis, meaning there's an excess of acid or loss of bicarbonate in the body. Normal base deficit ranges from -2 to +2 mEq/L, with values greater than +2 indicating increasing severity of metabolic acidosis 1. The base deficit helps clinicians assess the metabolic component of acid-base disorders separately from respiratory influences. It's particularly useful in trauma, shock, and critical care settings to evaluate tissue perfusion and oxygenation, as poor perfusion leads to lactic acid accumulation and increased base deficit.
Key Points to Consider
- The initial base deficit, obtained either from arterial or peripheral venous blood, provides an indirect estimation of global tissue acidosis due to impaired perfusion 1.
- Base deficit values are well correlated with shock and resuscitation, but do not strictly correlate with lactate levels in severely injured patients 1.
- The reliability of lactate determination may be lower when traumatic injury is associated with alcohol consumption, making base deficit a potentially better predictor of prognosis in such cases 1.
- Treatment depends on addressing the underlying cause, which may include fluid resuscitation, improving tissue perfusion, or administering bicarbonate in severe cases.
- The base deficit should always be interpreted alongside other ABG parameters and clinical findings for a comprehensive assessment of a patient's acid-base status.
Clinical Application
- In clinical practice, the base deficit can be used to guide resuscitation efforts and monitor the effectiveness of treatment in patients with traumatic-hemorrhagic shock 1.
- A severe base deficit (<-10 mEq/L) is associated with a higher risk of post-traumatic organ failure or death, and requires prompt and aggressive management 1.