Arterial Blood Gases Analysis and Theoretical Background

Theoretical Background

When analyzing arterial blood gases (ABGs), the pH value gives the number of hydrogen ions (H+) in the specimen, which is used in determining whether the blood sample is alkalotic or acidotic. The established normal pH values range from 7.35 to 7.45 (Lampert, 2020). Samples with pH values lower than the stipulated minimum standard value are acidic. In contrast, those whose values surpass the maximum normal level value are alkaline. Further, the value of the blood’s carbon dioxide levels, as exhibited by the partial pressure of carbon dioxide (PaCO₂), delineates whether the disorder is linked to respiratory issues. The normal values for PaCO₂ are between 35 mmHg and 45 mmHg (Lampert, 2020). Conversely, bicarbonate ions (HCO₃^–) relate to the patient’s renal system and ascertain whether the inherent condition is correlated with the metabolic variabilities. Normal values of HCO₃^– ranges from 22 mmol/L to 26 mmol/L (Lampert, 2020). Consequently, the ABG outcomes show whether the blood sample is experiencing acidosis or alkalosis and whether it is metabolic or respiratory.

The P_aCO₂ values exceed the normal range for the respiratory cause while the metabolic problems exhibit abnormal levels of HCO₃. During compensation, the system abnormality is examined by investigating counter components of the disorder. Subsequently, HCO₃^– levels are assessed for acidosis compensation, while PaCO₂ ascertains for alkalosis compensation (Lampert, 2020). If the opposite component is within the range, the issue is non-compensated. Partial compensation occurs when the problem is not settled, but the body is trying to fix it.

Table 1. pH, PaCO_2, and HCO₃^– values for ABG interpretation 

Questions

1. PH PaCO₃ HCO₃^– Interpretation
2. 7.48 32 34 Alkalosis, Respiratory, Uncompensated
3. 7.32 48 25 Acidosis, Respiratory, Compensated
4. 7.30 38 18 Acidosis, Metabolic, Partially Compensated
5. 7.28 60 29 Acidosis, Respiratory, Partially Compensated
6. 7.49 40 30 Alkalosis, Metabolic, Partially Uncompensated
7. 7.28 60 29 Acidosis, Respiratory, Partially Compensated
8. 7.50 49 38 Alkalosis, Respiratory, Partially Compensated
9. 7.31 32 15 Acidosis, Metabolic, Partially Compensated
10. 7.30 50 25 Acidosis, Respiratory, Compensated
11. 7.48 40 30 Alkalosis, Metabolic, Partially Compensated
12. 7.38 80 47 Normal, Respiratory, Partially Compensated

Reference

Lampert, L. (2020). Interpreting ABGs (arterial blood gases) made easy. Ausmed. Web.