Background: Cerebral oximetry (rSO 2) may be useful in assessing the probability of return of spontaneous circulation (ROSC). However, the potential of assessing the trend in the rSO 2 value has not been discussed when determining the probability of ROSC. Methods: This was a retrospective study of out-of-hospital cardiac arrest (OHCA) patients with continuous rSO 2 values recorded during cardiopulmonary arrest. We used logistic regression analysis at each time point to investigate the best subsets of rSO 2-related variables for ROSC, which included rSO 2 (baseline), the baseline value of rSO 2 ; amount of maximum rise, the maximum difference of rSO 2 from rSO 2 (baseline) over t minutes; DrSO 2 (t):(amount of maximum rise)/rSO 2 (baseline) over t minutes after hospital arrival. Results: Among the 90 included patients, 35 achieved ROSC. Area under the curve (AUC) analysis revealed that DrSO 2 over a 16-min measurement period was significantly higher than DrSO 2 measured over 4-, 8-, 12-, and 20-min periods. During this 16-min period, the subset showing the best AUC value was interaction of the amount of maximum rise and rSO 2 (baseline) rather than the amount of maximum rise or DrSO 2 alone (AUC = 0.91). Conclusions: The combination of rSO 2 (baseline) with the amount of maximum rise in rSO 2 value over time might be a new index for the prediction of ROSC that could be useful in guiding cardiopulmonary resuscitation. Further studies are needed to validate these findings.

BackgroundIn recent years, the measurement of cerebral regional oxygen saturation (rSO2) during resuscitation has attracted attention. The objective of this study was to clarify the relationship between the serial changes in the cerebral rSO2 values during extracorporeal cardiopulmonary resuscitation (ECPR) and the neurological outcome.MethodsWe measured the serial changes in the cerebral rSO2 values of patients with out-of-hospital cardiac arrest before and after ECPR in Osaka National Hospital.ResultsFrom January 2013 through March 2015, the serial changes in the cerebral rSO2 values were evaluated in 16 patients. Their outcomes, as measured by the Glasgow Outcome Scale (GOS) score at discharge, included good recovery (GR) (n = 4), vegetative state (VS) (n = 2), and death (D) (n = 10). In the poor neurological group (VS and D: n = 12; age, 52.8 ± 4.0 years), the cerebral rSO2 values showed a significant increase during ECPR (5 min before ECPR: 52.0 ± 1.8%; 2 min before ECPR: 56.1 ± 2.3%; 2 min after ECPR: 63.5 ± 2.2%; 5 min after ECPR: 66.4 ± 2.2%; 10 min after ECPR: 67.6 ± 2.3% [P < 0.01]). In contrast, in the good neurological group (GR: n = 4; age, 53.8 ± 6.9 years), the cerebral rSO2 values did not increase to a significant extent during ECPR (5 min before ECPR: 61.9 ± 3.1%; 2 min before ECPR: 57.1 ± 4.0%; 2 min after ECPR: 59.6 ± 3.8%; 5 min after ECPR: 61.0 ± 3.7%; 10 min after ECPR: 62.0 ± 3.8% [P = 0.88]). Our study suggested that the patients whose cerebral rSO2 values showed no significant improvement after ECPR might have had a good neurological prognosis.ConclusionsThe serial changes in the cerebral rSO2 values during ECPR may predict a patient’s neurological outcome. The further evaluation of the validity of rSO2 monitoring during ECPR may lead to a new resuscitation strategy.

The change in the EP, CM, SP and AP during perilymphatic perfusion of vasopressin (antidiuretic hormone) was examined in the guinea pig. The EP was recorded with a microelectrode through the spiral ligament of the second turn. The CM, SP and AP were measured with the differential electrodes in the basal turn. The perfusion of vasopressin at concentration of more than 10(-5)M produced a reversible decrease in the EP. The extent of the EP decline was dependent upon the concentration of vasopressin. Abolition of the effect of vasopressin upon the EP by the resumption of respiration after transient asphyxia was observed. During the perfusion of vasopressin, the CM and AP decreased, while the negative component of the SP increased. The mechanism causing the effect of vasopressin upon the cochlear potentials is discussed.

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.

The electrical resistance of the scala media (Rm) in the basal turn of the guinea pig was measured during perilymphatic perfusion with vasopressin. As the endocochlear potential (EP) diminished under the influence of vasopressin (0.1 mM), so the Rm increased. The Rm decreased when the EP decreased by vasopressin recovered above the pre-asphyctic level after the termination of temporary asphyxia. The present study demonstrates that the EP decrease produced by vasopressin is associated with the increase in Rm.