Paramedics deliver a 68-year-old nursing home resident to the acute care bay after staff found him profoundly lethargic amid multiple episodes of bilious emesis over the preceding 48 hours. Medical history is significant for heart failure with preserved ejection fraction, severe osteoarthritis, and recently diagnosed type 2 diabetes mellitus. On initial assessment, he is obtunded but protects his airway.
Vitals:
| Parameter | Value |
|---|---|
| Temperature | 36.8°C (98.2°F) |
| Heart rate | 118/min |
| Blood pressure | 88/54 mm Hg |
| Respiratory rate | 10/min |
| SpO2 | 93% (room air) |
Laboratory data:
| Test | Result |
|---|---|
| Sodium | 142 mEq/L |
| Potassium | 3.1 mEq/L |
| Chloride | 90 mEq/L |
| Bicarbonate | 16 mEq/L |
| Blood urea nitrogen | 58 mg/dL |
| Creatinine | 2.7 mg/dL |
| Glucose | 512 mg/dL |
Arterial blood gas (room air):
| Parameter | Value |
|---|---|
| pH | 7.23 |
| PaO2 | 74 mm Hg |
| PaCO2 | 40 mm Hg |
Assuming a normal reference anion gap of 12 mEq/L and a normal reference serum bicarbonate of 24 mEq/L, what is this patient's delta ratio ()?
Cevap: 3
Cevap
The patient's calculated delta ratio is 3.0.
This patient presents with a severe triple acid-base disorder: high anion gap metabolic acidosis (likely diabetic ketoacidosis or lactic acidosis from hypoperfusion), metabolic alkalosis (from severe vomiting), and respiratory acidosis (from obtundation causing hypoventilation). The delta ratio compares the rise in the anion gap () to the fall in bicarbonate (). For every 1 mEq/L increase in unmeasured acids, the bicarbonate should theoretically fall by 1 mEq/L, yielding a ratio of 1.0 (or up to 2.0 in lactic acidosis due to varying intracellular buffering efficiency). A ratio indicates that the bicarbonate has not fallen as much as expected given the massive acid load. In this patient, the massive acid load () only dropped the bicarbonate by 8 mEq/L. This proves the existence of a concurrent metabolic alkalosis (from the loss of gastric ) generating additional bicarbonate that masks the severity of the acidosis. Additionally, Winter's formula predicts a PaCO2 of mm Hg; the measured PaCO2 of 40 mm Hg confirms a concurrent respiratory acidosis.
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Anahtar Kavram
In patients with a high anion gap metabolic acidosis, the delta ratio () is calculated to uncover hidden concurrent metabolic disorders. A ratio greater than 2.0 indicates a superimposed metabolic alkalosis.
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