Comparison of Hemoglobin Values Obtained by Arterial Blood Gas Analysis versus Laboratory Method during Major Head-and-Neck Surgeries.

Background: Accuracy of hemoglobin (Hb) measured by arterial blood gas (ABG) analyzer is considered inferior to laboratory (lab) measurements as it could overestimate Hb levels.

Aim of the study: The study aims to compare Hb measured using ABG versus conventional lab method at the time of major blood loss and in the preoperative and immediate postoperative periods.

Settings and design: It was a prospective, nonrandomized observational study conducted in a tertiary care center.

Materials and methods: The study was conducted in 24 patients undergoing major head-and-neck surgeries. Simultaneous blood samples were sent for Hb measurement by ABG analysis and lab method at induction of anesthesia, when intraoperative blood loss exceeded maximum allowable blood loss, and in the immediate postoperative period.

Statistical analysis used: Chi-square test, independent sample's t-test, and paired t-test were used for statistical analysis.

Results: Mean Hb values obtained by both techniques were significantly different at all time points. Hb obtained by ABG analysis was significantly higher than lab value preoperatively (12.78 ± 2.51 vs. 12.05 ± 2.2, P = 0.038), at maximum blood loss (11.00 ± 2.57 vs. 9.87 ± 2.06, P = 0.006), and in the immediate postoperative period (11.96 ± 2.00 vs. 10.96 ± 2.24 P < 0.001). ABG Hb values were found to be approximately 1 g.dL^-1 greater than lab values.

Conclusion: Hb measured by ABG analysis was significantly higher than that measured by lab method at the time of major blood loss, preoperatively, and at the immediate postoperative period in patients undergoing major head-and-neck surgeries, with a good correlation of values obtained by both the techniques.