Correlation of Arterial and Central Venous Blood Gas Measurements in Critically Ill Patients at Intensive Care Unit of a Tertiary Care Center

Background and Objective: Arterial blood gas (ABG) analysis is an important step in assessing the adequacy of oxygenation and ventilation and for monitoring acid–base disturbances. Arterial puncture is associated with complications, so central venous blood gas analysis (CVBG) is used as an alternative to ABG analysis. The objective of this study is to assess the relationship between pH, bicarbonate (HCO 3 ), partial pressure of oxygen, base excess, and partial pressure of carbon dioxide (PCO 2 ) values obtained from arterial and central venous blood samples in critically ill patients admitted to an intensive care unit (ICU). Materials and Methods: This single-center, prospective study aimed to assess the correlation between ABG and CVBG measurements among patients admitted to the medicine ICU. Two paired blood samples of both arterial and venous blood, 12 h apart, were collected from 30 patients. The correlation between ABG and CVBG was computed using Epi Info software. Results: The mean ± standard deviation (SD) of arterial pH and PCO 2 was 7.36 ± 0.09 and 35.47 ± 9.74, respectively. The mean ± SD of venous pH and PCO 2 was 7.36 ± 0.10 and 35.69 ± 9.99, respectively. The correlation between arterial and venous pH was r = 0.79 ( P < 0.001), and PCO 2 was r = 0.90 ( P < 0.001). The mean ± SD of arterial HCO 3 and base excess was 17.75 ± 8.56 and − 1.67 ± 8.82, respectively. The mean ± SD of venous HCO 3 and base excess was 18.98 ± 5.80 and − 1.98 ± 9.46, respectively. The correlation between arterial and venous HCO 3 was r = 0.87 ( P < 0.001), and base excess was r = 0.81 ( P < 0.001), suggesting a statistically significant correlation in the aforementioned parameters. Conclusion: Our study demonstrates a strong correlation between ABG and CVBG for pH, PCO 2 , HCO 3 , and base excess. These findings suggest that CVBG analysis can be a reliable alternative to ABG analysis in critically ill ICU patients, especially in resource-limited settings. This approach can reduce patient discomfort and complications associated with arterial punctures, streamlining emergency care.