Noninvasive hemoglobin monitoring by spectrophotometry in blunt abdominal trauma patients for conservative management

Background & Aim: Nonoperative management is considered the treatment of choice in patients with blunt abdominal trauma, serial clinical assessment and hemoglobin (Hb) measurements is the cornerstone for their evaluation. While automated laboratory analysis is the reference method for measuring Hb, spectrophotometry may be better by allowing non-invasive instant readings. This study aimed to evaluate the accuracy of spectrophotometric non-invasive Hb monitoring (SpHb) and whether it's possible to rely upon in making the decision for operative management or not.Methodology: a cross-sectional observational study at which 39 patients admitted to our surgical intensive care unit (ICU) following blunt abdominal trauma were subjected to serial measurements of SpHb using an oximeter probe (Radical-7TM; Masimo Corp., Irvine, CA), and simultaneous blood samples analyzed using Coulter LH 750 Cell Counter, measurements were done every 8 hours till discharge or admission to operation room, the accuracy and precision of SpHb were evaluated.Results: The limits of agreement between conventional and noninvasive Hb assays were clinically unacceptable and ranging from-6.45 g/dl (95% CI =-7.54 to-5.37 g/dl) to 4.82 g/dl (95% CI = 3.74 to 5.91 g/dl). The mean difference (bias) was-0.82 g/dl (95% CI =-1.45 to-0.19), the correlation between SpHb and laboratory values was statistically insignificant (r = 0.19, 95% CI =-0.03 to 0.39, P = 0.095, R2 = 0.03).Conclusion: Spectrophotometric noninvasive hemoglobin measurement didn't offer enough accuracy nor precision and shouldn't be relied upon in deciding operative management of blunt abdominal trauma patients admitted to ICU under observation.