Correlation of arterial blood gas measurement with peripheral venous blood gas values in adults patients admitted in ICU

Arterial blood gas (ABG) sampling is an essential investigation for assessment of acid-base status, oxygenation and ventilation in critical care practice. Arterial puncture to obtain arterial blood is more invasive procedure than venous and has more potential complications. To find out the correlation between arterial and peripheral venous blood gas values for pH, PCO2 and bicarbonate. Patients admitted in ICU requiring arterial blood gas analysis to determine their acid-base status or ventilatory status was included in the study. One milliliter of venous blood was obtained in a heparin flushed syringe within 5 minutes of getting arterial blood sample. Both labeled samples were processed immediately. Data were analyzed by student’s t-test. A total of 50 paired samples from 36 patients were evaluated. The mean differences between arterial and venous blood gas values for pH, PCO2 and bicarbonate were 0.02 units, -2.37 mmHg and -0.45 mEq/L respectively. Similarly, the correlation coefficients between arterial and venous parameters were 0.964, 0.881 and 0.906 for pH, PCO2 and bicarbonate respectively, which were statistically significant (p<0.001). Venous pH, PCO2 and bicarbonate showed a very high level of correlation with the respective arterial values.