Abstract
Background
Non-invasive hemoglobin measurement was introduced to potentially eliminate blood draws postoperatively. We compared the accuracy and effectiveness of a non-invasive hemoglobin measurement system with a traditional blood draw in patients undergoing total joint arthroplasty.
Methods
After IRB approval, 100 consecutive patients undergoing primary total hip or knee arthroplasty had their hemoglobin level tested by both traditional blood draw and a non-invasive hemoglobin monitoring system. Results were analyzed for the entire group, further stratifying patients based on gender, race, surgery (THA versus TKA), and post-operative hemoglobin level. Finally, we compared financial implications and patient satisfaction with the device. Paired t-test with 0.05 conferring significance was used. Stratified analyses of the absolute difference between the two measures were assessed using Mann- Whitney test. To assess the level of agreement between the two measures, the concordance correlation coefficient (CCC) was calculated.
Results
Mean blood-draw hemoglobin value on POD1 was 11.063 ± 1.39 g/dL and 11.192 ± 1.333 g/dL with the non-invasive device. For all patients, the mean absolute difference between the two methods was 0.13 g/dL (p = 0.30). The CCC between the two methods was 0.58, conferring a moderate to strongly positive linear relationship (Figure 1).
Non-invasive measurement was preferred by 100% of patients with a mean VAS score of 0/10. Additionally, the cost savings with the non-invasive system was $16.50 per patient.
Discussion
Overall, there was no significant difference between the hemoglobin level obtained by traditional laboratory methods versus the Masimo Radical-7 system on post-operative day #1 in patients who underwent total joint arthroplasty. In the minority of patients (19%) who had a hemoglobin level of less than 10 g/dL, the difference between the two methods was statistically significant. Additionally, 100% of patients preferred the Masimo device to a traditional blood draw and the Masimo device was substantially cheaper. While further investigation of non-invasive hemoglobin monitoring systems is necessary, particularly in patients with a post-operative hemoglobin of less than 10 g/dL, our study shows that the Masimo Radical-7 device provides an accurate, preferable, and less expensive alternative to a traditional blood draw after total joint replacement.
Conclusion
Overall, the non-invasive hemoglobin monitoring system offered a similar hemoglobin reading to the standard lab-draw reading, while improving satisfaction and lowering cost. The system relies on adequate perfusion for measurement, and our study demonstrated that lower hemoglobin values may reduce finger-tip perfusion and affect the hemoglobin reading.
