Abstract: PUB119
Compensatory Rules for Simple Acid-Base Disorders
Session Information
Category: Fluid, Electrolyte, and Acid-Base Disorders
- 902 Fluid, Electrolyte, and Acid-Base Disorders: Clinical
Authors
- Fallahzadeh, Mohammad Amin, Department of Internal Medicine, Baylor University Medical Center, Dallas, Texas, United States
- Fallahzadeh Abarghouei, Mohammad Kazem, Division of Nephrology, Unverisity of California San Francisco, San Francisco, California, United States
- Emmett, Michael, Department of Internal Medicine, Baylor University Medical Center, Dallas, Texas, United States
Background
Most acid-base compensatory equations are based on limited numbers of human observations. We searched the literature for all studies addressing the issue of acid-base disorder compensation. We then utilized all the available data to create an acid-base compensation diagram and generate more accurate compensatory equations.
Methods
We used 84 published articles that evaluated the acid-base blood gas parameters of patients with simple acid-base disorders. We extracted the measured bicarbonate and PCO2 values of the observations in these articles to calculate the most accurate compensatory formulas for simple acid-base disorders.
Results
Our database was comprised of 3806 observations with simple acid-base disorders. Our results generally agreed with the Goldberg acid-base nomogram except for patients with severe metabolic alkalosis (Figure 1). The best proposed formula in the literature for simple acid-base disorders and the compensatory formulas generated by our data are illustrated in Table 1.
Conclusion
Although the formulas described in the literature perform relatively well in predicting the appropriate compensatory response to simple acid-base disorders, more accurate predictive formulas were developed.
Table 1. The best proposed equations in the literature and most accurate formulas for simple acid-base disorders
| Primary acid-base disorder | The best proposed formula in the literature | Most accurate formula (Regression line) |
| Metabolic acidosis | PCO2 = (1.5 × HCO3) + 8 ± 2 (Winters’ equation) | PCO2 = (1.29 × HCO3) + 9.82 |
| Metabolic alkalosis | PCO2 = HCO3 + 15 | PCO2 = (0.77 × HCO3) + 20.41 |
| Acute respiratory acidosis | ΔHCO3 = (0.1 × ΔPCO2) | ΔHCO3 = (0.07 × ΔPCO2) + 1.26 |
| Chronic respiratory acidosis | ΔHCO3 = (0.4 × ΔPCO2) | ΔHCO3 = (0.24 × ΔPCO2) + 4.26 |
| Acute respiratory alkalosis | ΔHCO3 = (0.2 × ΔPCO2) | ΔHCO3 = (0.33 × ΔPCO2) – 1.20 |
| Chronic respiratory alkalosis | ΔHCO3 = (0.5 × ΔPCO2) | ΔHCO3 = (0.46 × ΔPCO2) – 0.19 |
Figure 1. Comparison our data points (a) with acid-base map proposed by Goldberg et al. (b)