Effectiveness of the hemoglobin index for screening of subarachnoid hemorrhage in out‐of‐hospital cardiopulmonary arrest patients: a retrospective observational study

Abstract

The hemoglobin index (HbI) represents the amount of hemoglobin, which reflects regional tissue blood volume. The HbI is calculated in real time by a regional oxygen saturation (rSO 2) monitor. For the hypothesis of our HbI project, we theorized that HbI could be a new method for the screening of subarachnoid hemorrhage (SAH) in overcrowded emergency departments. As a first step, this study aimed to clarify the effectiveness of HbI in screening SAH in out-of-hospital cardiopulmonary arrest (OHCA) patients using the rSO 2 data of our previous studies. Methods: In this single-center, retrospective, observational study, we examined HbI in patients with OHCA transferred to the Trauma and Acute Critical Care Center at Osaka University Hospital (Osaka, Japan) during the period between April 2013 and December 2015. A sensor attached to the patient's forehead monitored HbI continuously. Results: Among 63 patients (40 men and 23 women; mean age, 76 [interquartile range (IQR), 66-85] years) with OHCA, five were diagnosed as having SAH (SAH group) and 58 were not (non-SAH group). The HbI values were significantly higher in the SAH group than in the non-SAH group (1.35 [IQR: 0.80-2.69] versus 0.41 [IQR: 0.32-0.61]), P = 0.0042). In the SAH group, with an HbI cutoff value of 1.18, the specificity and sensitivity were 96% and 80%, respectively, and the area under the receiver operating characteristic curve of HbI was 0.89. Conclusions: The HbI might be useful for the screening of SAH in patients with OHCA. The application of HbI in the emergency department could be expected in the future.

Dynamic changes of the hemoglobin index during resuscitation in patients with out-of-hospital cardiopulmonary arrest due to freshwater drowning: A retrospective observational study

“…An rSO 2 monitor (TOS-OR; TOS-TEC., Tokyo, Japan) [6] , [8] , [14] was used to measure the cerebral rSO 2 and HbI values. The TOS-OR system measures the oxygen saturation based on the Beer–Lambert law, using three different wavelengths of near-infrared LED light, with absorbance specific to oxyhemoglobin and deoxyhemoglobin.…”

“…The HbI represents the amount of hemoglobin that is present just beneath the sensor [8] , [14] . This does not reflect the local hemoglobin concentration around the brain cortex.…”

“…Our group has reported the effect of cerebral rSO 2 monitoring during resuscitation in patients with out-of-hospital cardiac arrest (OHCA) for several years [2] , [3] , [4] , [5] , [6] , [7] . In addition to cerebral rSO 2 , we have also recorded the hemoglobin index (HbI) [8] . The HbI is the amount of hemoglobin measured by near-infrared radiation and is determined by the measurement of light intensity received at 805 nm.…”

Usefulness of simultaneous measurement of brain and muscle regional oxygen saturation in shock patients: A report of three cases

“…We hypothesized that we could evaluate the oxygen supply‐demand balance between brain and muscle tissue by simultaneously measuring rSO₂ values of the brain and muscle tissues of patients in shock using an rSO₂ monitor (TOS‐OR; TOSTEC CO). 5 , 6 The study protocol was approved by the Institutional Review Board of Osaka University (approval no. 19540), which waived the need to obtain patient written informed consent because this was a noninvasive observational study.…”