2005 Papers - Biuk-Aghai
BLOOD VOLUME MEASUREMENTS IN CRITICALLY ILL PATIENTS
Elisabeth Biuk-Aghai, MD, University of Hawaii Surgical Residency Program
Introduction: Determining fluid status in critically ill patients is of vital importance in their management. Current clinical tools such as vital signs, Pulmonary Artery Catheter (PAC) data, urine output, laboratory values and chest X-Ray may be difficult to interpret. Technology to measure blood volume (BV) with radioisotopes has been available for over 50 years. A bedside kit facilitates its use in clinical setting. Whether BV information would lead to treatment change when compared to traditional parameters is unknown.
Hypothesis: BV measurements may alter treatment in comparison to data gathered by traditional methods.
Methods: A prospective observational study of BV measurements followed by a retrospective chart review. The treating team during morning rounds identified SICU patients who may benefit from BV assessment. BVA-100 (Daxor, NY) uses injection of I-131 with serial blood draws to calculate blood volume, plasma volume and RBC mass. Simultaneously with the BV measurements, the traditional parameters used for determining fluid status of patients were measured: blood pressure, heart rate, urine output, PAC measurements, Hb/Hct, ABG, B-natriuretic peptide (BNP), BUN/Creatinine and CXR. Patients were treated utilizing these values but not BV measurements. After unblinding the BV information, the team determined whether the BV data would have resulted in different fluid and blood management.
Results: 8 patients contributed 29 data points. Age +/- SD was +/- 8 years, APACHE II score ranged 16 +/- 4. Five patients had severe sepsis/septic schock, 1 had ARDS, 1 had severe RV failure from cardiac contusion and 1 was a pre-operative optimization. 5 patients had a PAC and generated 20 data points. In 10 out of 20 occasions (50%) the BV information would have resulted in a different treatment. 6 would have received less fluid, 2 would not have been transfused blood, one would not have received blood or fluid and one did require more fluid. 9 data points came from patients without PAC and in 3 out of 9 times (33%) a different treatment would have been selected. 2 would have been transfused blood and 1 would have received more fluid. There was no correlation (p>0.05) between % BV and the following variables: PAOP, CVP, BNP and SVI.
Conclusion: BV measurement is the gold standard for assessing patient fluid status. The addition of BV information could make a significant difference in clinical management as suggested in this small sample. Our data and previous studies do suggest that the conventional clinical parameters can be inaccurate. Whether the use of BV studies in clinical practice will impact outcome needs to be determined.