Effects of positive end-expiratory pressure on intracranial pressure,cerebral perfusion pressure,and brain oxygenation in acute brain injury:Friend or foe?A scoping review

Background Patients with acute brain injury(ABI)are a peculiar population because ABI does not only affect the brain but also other organs such as the lungs,as theorized in brain–lung crosstalk models.ABI patients often require mechanical ventilation(MV)to avoid the complications of impaired respiratory function that can follow ABI;MV should be settled with meticulousness owing to its effects on the intracranial compartment,especially regarding positive end-expiratory pressure(PEEP).This scoping review aimed to(1)describe the physiological basis and mechanisms related to the effects of PEEP in ABI;(2)examine how clinical research is conducted on this topic;(3)identify methods for setting PEEP in ABI;and(4)investigate the impact of the application of PEEP in ABI on the outcome.Methods The five-stage paradigm devised by Peters et al.and expanded by Arksey and O'Malley,Levac et al.,and the Joanna Briggs Institute was used for methodology.We also adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses(PRISMA)extension criteria.Inclusion criteria:we compiled all scientific data from peer-reviewed journals and studies that discussed the application of PEEP and its impact on intracranial pressure,cerebral perfusion pressure,and brain oxygenation in adult patients with ABI.Exclusion criteria:studies that only examined a pediatric patient group(those under the age of 18),experiments conducted solely on animals;studies without intracranial pressure and/or cerebral perfusion pressure determinations,and studies with incomplete information.Two authors searched and screened for inclusion in papers published up to July 2023 using the PubMed-indexed online database.Data were presented in narrative and tubular form.Results The initial search yielded 330 references on the application of PEEP in ABI,of which 36 met our inclusion criteria.PEEP has recognized beneficial effects on gas exchange,but it produces hemodynamic changes that should be predicted to avoid undesired consequences on cerebral blood flow and intracranial pressure.Moreover,the elastic properties of the lungs influence the transmission of the forces applied by MV over the brain so they should be taken into consideration.Currently,there are no specific tools that can predict the effect of PEEP on the brain,but there is an established need for a comprehensive monitoring approach for these patients,acknowledging the etiology of ABI and the measurable variables to personalize MV.Conclusion PEEP can be safely used in patients with ABI to improve gas exchange keeping in mind its potentially harmful effects,which can be predicted with adequate monitoring supported by bedside non-invasive neuromonitoring tools.

Amplitude-Integrated Electroencephalography Predicts Outcome in Patients with Coma After Acute Brain Injury

Prognostication of coma patients after brain injury is important, yet challenging. In this study, we evaluated the predictive value of amplitude-integrated electroencephalography （aEEG） for neurological outcomes in coma patients. From January 2013 to January 2016, 128 coma patients after acute brain injury were prospectively enrolled and monitored with aEEG. The 6-month neurological outcome was evaluated using the Cerebral Performance Category Scale. aEEG monitoring commenced at a median of 7.5 days after coma onset. Continuous normal voltage predicted a good 6-month neurological outcome with a sensitivity of 93.6% and specificity of 85.2%. In contrast, continuous extremely low voltage, burst-suppression, or a flat tracing was correlated with poor 6-month neurological outcome with a sensitivity of 76.5% and specificity of 100%. In conclusion, aEEG is a promising predictor of 6-month neurological outcome for coma patients after acute brain injury.

The electrocardiographic changes in acute brain injury patients

Background Electrocardiographic （ECG） changes occurring during the course of acute brain injury （ABI） have been described frequently, but their significances remain uncertain. The present study was designed to investigate the relation of ECG abnormalities to outcome in the patients with ABI. Methods We performed a retrospective, observational study on the ABI patients admitted to the Department of Neurosurgery of the Beijing Tiantan Hospital between December 2005 and December 2007. All the patients accepted 12-lead electrocardiographic examination within 24 hours after injury, then divided into three groups according to the Glasgow coma score （GCS）. In-hospital mortality and one-month outcome assessed by the Glasgow outcome score （GOS） were investigated. Results Of 335 ABI patients （mean ages 32.4 years）, 246 patients （73.4%） had abnormal ECGs. The most common abnormality was ST-T changes （41.5%）, followed by sinus tachycardia （23.6%）. ECG changes had a significant association with the severity and outcome. Logistic regression analysis showed the presence of ST-T changes （OR 2.587, 95%C/1.009 to 6.629, P=0.048） and QT dispersion prolongation （OR 4.656, 95%C/1.956 to 11.082, P=0.001） significantly associated with short outcomes. Conclusions ABI can lead to myocardial damage and ECG changes had a significant association with the severity. ST-T changes and QT dispersion prolongation were the independent prognosis factors for the negative outcome of ABI patients.

Morphometric changes in the cortex following acute mild traumatic brain injury

Morphometric changes in cortical thickness(CT),cortical surface area(CSA),and cortical volume(CV) can reflect pathological changes after acute mild traumatic brain injury(m TBI).Most previous studies focused on changes in CT,CSA,and CV in subacute or chronic m TBI,and few studies have examined changes in CT,CSA,and CV in acute m TBI.Furthermore,acute m TBI patients typically show transient cognitive impairment,and few studies have reported on the relationship between cerebral morphological changes and cognitive function in patients with m TBI.This prospective cohort study included 30 patients with acute m TBI(15 males,15 females,mean age 33.7 years) and 27 matched healthy controls(12 males,15 females,mean age 37.7 years) who were recruited from the Second Xiangya Hospital of Central South University between September and December 2019.High-resolution T1-weighted images were acquired within 7 days after the onset of m TBI.The results of analyses using Free Surfer software revealed significantly increased CSA and CV in the right lateral occipital gyrus of acutestage m TBI patients compared with healthy controls,but no significant changes in CT.The acute-stage m TBI patients also showed reduced executive function and processing speed indicated by a lower score in the Digital Symbol Substitution Test,and reduced cognitive ability indicated by a longer time to complete the Trail Making Test-B.Both increased CSA and CV in the right lateral occipital gyrus were negatively correlated with performance in the Trail Making Test part A.These findings suggest that cognitive deficits and cortical alterations in CSA and CV can be detected in the acute stage of m TBI,and that increased CSA and CV in the right lateral occipital gyrus may be a compensatory mechanism for cognitive dysfunction in acute-stage m TBI patients.This study was approved by the Ethics Committee of the Second Xiangya Hospital of Central South University,China(approval No.086) on February 9,2019.

Effects of Remifentanil Pretreatment on Inflammatory Response in Rats with Acute Cerebral Ischemia Injury

[Objectives]This study was conducted to investigate the effects of remifentanil pretreatment on inflammatory factors in rats with acute cerebral ischemia.[Methods]Sixty SD rats were randomly divided into the normal control group,sham operation group,ischemic brain injury group,and remifentanil pretreatment group.Except the normal control group,each group was divided into three subgroups(six in each group)according to the sampling time points of 6,12 and 24 h after execution.After modeling,the rats were scored for neurological deficit,and observed for pathological changes of neurons in the brain tissue by HE staining and the brain infarct volume by TTC staining,and the expression levels of TNF-α,IL-6 and IL-8 were detected by RT-PCR.[Results]HE staining:No significant changes were observed in the pathological morphology of the brain tissue in the blank group and sham operation group;and the neuronal structure of rats in the acute cerebral ischemia group was obviously damaged,and the neuronal damage in the remifentanil pretreatment group was less than that in the acute cerebral ischemia group at each time point.TTC staining:The gray brain infarct area in the remifentanil pretreatment group was significantly smaller than that in the cerebral ischemia group(P<0.05).RT-PCR detection results:The expression levels of TNF-α,IL-6 and IL-8 in the blank group and sham surgery group did not show significant changes at different times(P>0.05);and compared with the cerebral ischemia group,the expression levels of TNF-α,IL-6,and IL-8 in the remifentanil pretreatment group were significantly reduced at all time points(P<0.05).[Conclusions]Remifentanil pretreatment could protect the brain by reducing the expression of inflammatory factors after cerebral ischemia injury.

Effect of Early Controlled Hypotension on Patients with Traumatic Brain Injury

Objective:To investigate the clinical effect of early controlled hypotensive therapy in patients with traumatic braininjury(TBI).Methods:68 patients with acute 1Bl in our hospital were selected for this investigation.They were evenly divided into a control group and an observation group according to the difference of blood pressure and basic level,whose lesion area after treatment,postoperative intracranial pressure after 2 d and 7d,and Gcs score of prognostic quality before and after treatment were made comparison.Results:The post-treatment lesion area of the observation group was lower than that in the control group(P<0.05);the postoperative intracranial pressure after 2d and 7d of the control group was better than the observation group(P<0.05),and the same with GCS score,which has statistical sigmificance(P< 0.05).Conclusion:Early controlled hypotensive therapy has a significant clinical effect on patients with brain trauuma,it can reduce the lesion area after treatment and postoperative intracranial pressure as well.