Neuroprotection of hyperbaric oxygen therapy in sub-acute traumatic brain injury:not by immediately improving cerebral oxygen saturation and oxygen partial pressure

Although hyperbaric oxygen （HBO） therapy can promote the recovery of neural function in patients who have suffered traumatic brain injury （TBI）, the underlying mechanism is unclear. We hypothesized that hyperbaric oxygen treatment plays a neuroprotective role in TBI by increasing regional transcranial oxygen saturation （rSO2） and oxygen partial pressure （PaO2）. To test this idea, we compared two groups： a control group with 20 healthy people and a treatment group with 40 TBI patients. The 40 patients were given 100% oxygen of HBO for 90 minutes. Changes in rSO2 were measured. The controls were also examined for rSO2 and PaO2, but received no treatment, rSO2 levels in the patients did not differ significantly after treatment, but levels before and after treatment were significantly lower than those in the control group. PaO2 levels were significantly decreased after the 30-minute HBO treatment. Our findings suggest that there is a disorder of oxygen metabolism in patients with sub-acute TBI. HBO does not immediately affect cerebral oxygen metabolism, and the underlying mechanism still needs to be studied in depth.

Effect of Hemodilution on Fluctuation of Cerebral Oxygen Saturation during Cardiopulmonary Bypass in Children with Cyanotic Congenital Heart Disease

Background:In patients with cyanotic congenital heart disease(CHD),cerebral oxygenation may be maintained by elevations in hematocrit(Hct).Hemodilution accompanying cardiopulmonary bypass(CPB),however,can disrupt cerebral oxygen balance,leading to fluctuations in cerebral oxygen saturation(ScO_(2)).The present study investigated the effects of Hct changes on the fluctuation of ScO_(2)during CPB in cyanotic CHD using performance measurement(PM).Methods:Children with CHD(51 acyanotic and 46 cyanotic)who had undergone cardiac surgery using CPB were enrolled.Median performance error(MDPE),median absolute performance error(MDAPE),and wobble parameters of ScO_(2)were calculated before(reference value),during,and after CPB.Correlations of PM parameters with Hct and reductions in Hct(ΔHct)were also evaluated.Results:Before CPB,patients with cyanotic CHD had lower MDPE and larger wobble than those with acyanotic CHD,although mean ScO_(2)did not differ significantly between the two groups.During CPB,ScO_(2)of acyanotic CHD increased asΔHct increased,but PM variables were not associated withΔHct.In cyanotic CHD,MDPE(r=−0.324,p=0.032)and MDAPE(r=0.339,p=0.024)correlated significantly withΔHct during CPB.After CPB,MDPE(r=0.574,p=0.025)and MDAPE(r=−0.543,p=0.036)were significantly correlated with Hct in children with cyanotic CHD who underwent palliative surgery.Conclusion:Therefore,ScO_(2)fluctuation during CPB in children with cyanotic CHD may be affected by the decrease in Hct,suggesting that excessive hemodilution can negatively influence the maintenance of cerebral oxygenation in these patients.

Cerebral autoregulation-directed optimal blood pressure management reduced the risk of delirium in patients with septic shock

Background When resuscitating patients with septic shock,cerebrovascular reactivity parameters are calculated by monitoring regional cerebral oxygen saturation(rSO_(2))using near-infrared spectroscopy to determine the optimal blood pressure.Here,we aimed to analyze the impact of cerebral autoregulation-directed optimal blood pressure management on the incidence of delirium and the prognosis of patients with septic shock.Methods This prospective randomized controlled clinical study was conducted in the Xiangya Hospital of Central South University,China.Fifty-one patients with septic shock(December 2020–May 2022)were enrolled and randomly allocated to the experimental(n=26)or control group(n=25).Using the ICM+software,we monitored the dynamic changes in rSO_(2) and mean arterial pressure(MAP)and calculated the cerebrovascular reactivity parameter tissue oxygen reactivity index to determine the optimal blood pressure to maintain normal cerebral autoregulation function during resuscitation in the experimental group.The control group was treated according to the Surviving Sepsis Campaign Guidelines.Differences in the incidence of delirium and 28-day mortality between the two groups were compared,and the risk factors were analyzed.Results The 51 patients,including 39 male and 12 female,had a mean age of(57.0±14.9)years.The incidence of delirium was 40.1%(23/51),and the 28-day mortality rate was 29.4%(15/51).The mean MAP during the first 24 h of intensive care unit(ICU)admission was higher([84.5±12.2]mmHg vs.[77.4±11.8]mmHg,P=0.040),and the incidence of delirium was lower(30.8%vs.60.0%,P=0.036)in the experimental group than in the control group.The use of cerebral autoregulation-directed optimal blood pressure(odds ratio[OR]=0.090,95%confidence interval[CI]:0.009 to 0.923,P=0.043)and length of ICU stay(OR=1.473,95%CI:1.093 to 1.985,P=0.011)were risk factors for delirium during septic shock.Vasoactive drug dose(OR=8.445,95%CI:1.26 to 56.576,P=0.028)and partial pressure of oxygen(PaO_(2))(OR=0.958,95%CI:0.921 to 0.996,P=0.032)were the risk factors for 28-day mortality.Conclusions The use of cerebral autoregulation-directed optimal blood pressure management during shock resuscitation reduces the incidence of delirium in patients with septic shock.