NAPLES, FLA. – Spot-check hemoglobin testing can provide immediate and accurate hemoglobin measurements in trauma patients without removing a drop of blood, a prospective cohort study shows.
"The noninvasive hemoglobin monitor, I think, will change the way we practice," Dr. Bellal Joseph said at the annual scientific assembly of the Eastern Association for the Surgery of Trauma.
Continuous, noninvasive hemoglobin (Hgb) devices have been around for years, but studies showed poor correlation with invasive Hgb blood draws in trauma patients. Advances in technology, including more sensitive sensors and a wider range of sensor sizes, allow new spot-check devices to more accurately measure a broader range of patients with a wider range of finger diameters.
Dr. Joseph, a trauma and critical care surgeon at the University of Arizona Medical Center, Tucson, and his colleagues simultaneously obtained invasive and spot-check Hgb measurements in a prospective cohort of 525 trauma patients. Spot-check Hgb was measured three times upon presentation to the Level 1 trauma center using the Pronto-7 pulse CO-oximeter device and correlated with each invasive Hgb measurement.
According to the analysis, the success rate for spot-check Hgb testing was 86% in the mostly male cohort (74%), with a mean Injury Severity Score of 20, and average age of 41 years.
The mean hemoglobin for the 450 invasive Hgb measurements was 11.5 g/dL and 11.4 g/dL for the 1,350 Pronto-7 spot-checks, Dr. Joseph said.
Sensitivity for the spot-check device was 96%, specificity 44%, positive predictive value 73%, and negative predictive value 88% in patients with a hemoglobin above and below 8 g/dL. In all, 38% of patients had a hemoglobin level of less than 8 g/dL.
A Bland-Altman plot showed that 98.7% of readings were within two standard deviations. Spearman’s rank correlation coefficient revealed spot-check Hgb had a strong correlation with invasive Hgb testing (R2 = 0.77; R = 0.86), Dr. Joseph said.
"This device is a lot better than the continuous one we used to have, which they use in the operating room a lot," he said during the poster presentation. "We’re currently looking at it in patients who have blunt spleen or blunt liver injuries. Instead of ordering q6 hour, invasive hemoglobins, we’re just putting the monitor on and seeing if we can make clinical decisions based on that."
The palm-sized Pronto-7 spot-check device also has a perfusion index to help identify patients with early shock, but this has yet to be studied or integrated into practice.
"The one concern that I still have with this device is that 14% of our patients didn’t pick up a hemoglobin, and why is that?" Dr. Joseph said. Fashion may be, in part, to blame, with readings more likely to fail in patients with nail polish on, he added.
The next phase of the study will include implementation of the spot-check device on the floors and in the ICU with the nursing staff and direct uploading of results into patient charts. A time-savings analysis also will be done.
Dr. Joseph and his coauthors reported having no financial disclosures or study support.