Optimal Cerebral Perfusion Pressure: Targeted Treatment for Severe Traumatic Brain Injury.

Identification of individual therapy targets is critical for traumatic brain injury (TBI) patients. Clinical outcomes depend on cerebrovascular autoregulation (CA) impairment. Here, we compare the effectiveness of optimal cerebral perfusion pressure (CPPopt)-targeted therapy in younger (<45 years of age) and elderly (≥45 years of age) TBI patients. Single-center multi-modal invasive arterial blood pressure(t), intracranial pressure (ICP)(t), cerebral perfusion pressure CPP(t), and CPPopt(t) monitoring (n = 81) was performed. ICM+ software was used for continuous CPPopt(t) status assessment by identification of pressure reactivity index (PRx). The most significant prognostic factors were age, Glasgow Coma Scale, serum glucose, and duration of longest CA ompairment event (LCAI) when PRx(t) >0.5 within 24 h after admission. The modeled accuracies for favorable and unfavorable outcome prediction were 86.5% and 90.9%, respectively. Age above 45 years and averaged ICP during all monitoring time above 21.3 mm Hg was associated with unfavorable outcome of an individual patient. Averaged CPP values close to CPPopt were associated with a better outcome in younger patients. Averaged ΔCPPopt <-5.0 mm Hg, averaged PRx >0.36, and LCAI >100 min were significantly associated with mortality for the younger patients. The critical values of averaged PRx >0.26 and LCAI >61 min were significantly associated with mortality for the elderly group. Autoregulation-guided treatment was important for individual TBI management, especially in younger patients. Further randomized multi-center studies are needed to prove final benefit.

Cerebrovascular autoregulation impairments during cardiac surgery with cardiopulmonary bypass are related to postoperative cognitive deterioration: prospective observational study.

BACKGROUND: Postoperative cognitive dysfunction (POCD) occurs in approximately 33-83% of patients after cardiac surgery with cardiopulmonary bypass (CPB). Recent clinical data suggest that real-time, intraoperative monitoring of patient-specific cerebrovascular autoregulation (CA) may help to prevent POCD by detecting individual critical limits for mean arterial pressure (MAP) outside which CA is impaired. Objectives of the study were to detect the episodes of impaired CA during cardiac surgery with CPB, and to investigate the association between CA impairment and POCD. METHODS: The observational study of non-invasive ultrasonic volumetric CA monitoring included 59 patients undergoing elective coronary artery bypass graft surgery with CPB. All patients underwent series of neuropsychological tests the day before and ten days after the surgery in order to evaluate cognitive function. RESULTS: Twenty-two patients (37%) experienced POCD, 37 patients (63%) showed no cognitive deterioration. The duration of the single longest CA impairment event was found reliably associated with occurrence of POCD (P<0.05). The critical duration of the single longest CA impairment event was 5.03 minutes (odds ratio 14.5; CI 3.9-51.8) for studied population. CONCLUSIONS: Prospective clinical study showed that single longest CA impairment may result in post-operative deterioration of mental abilities. The duration of the single longest CA impairment event is the risk factor that is associated with POCD.

Non-invasive Cerebrovascular Autoregulation Assessment Using the Volumetric Reactivity Index: Prospective Study.

BACKGROUND: This prospective study of an innovative non-invasive ultrasonic cerebrovascular autoregulation (CA) monitoring method is based on real-time measurements of intracranial blood volume (IBV) reactions following changes in arterial blood pressure. In this study, we aimed to determine the clinical applicability of a non-invasive CA monitoring method by performing a prospective comparative clinical study of simultaneous invasive and non-invasive CA monitoring on intensive care patients. METHODS: CA was monitored in 61 patients with severe traumatic brain injuries invasively by calculating the pressure reactivity index (PRx) and non-invasively by calculating the volumetric reactivity index (VRx) simultaneously. The PRx was calculated as a moving correlation coefficient between intracranial pressure and arterial blood pressure slow waves. The VRx was calculated as a moving correlation coefficient between arterial blood pressure and non-invasively-measured IBV slow waves. RESULTS: A linear regression between VRx and PRx averaged per patients' monitoring session showed a significant correlation (r = 0.843, p < 0.001; 95% confidence interval 0.751 - 0.903). The standard deviation of the difference between VRx and PRx was 0.192; bias was - 0.065. CONCLUSIONS: This prospective clinical study of the non-invasive ultrasonic volumetric reactivity index VRx monitoring, based on ultrasonic time-of-flight measurements of IBV dynamics, showed significant coincidence of non-invasive VRx index with invasive PRx index. The ultrasonic time-of-flight method reflects blood volume changes inside the acoustic path, which crosses both hemispheres of the brain. This method does not reflect locally and invasively-recorded intracranial pressure slow waves, but the autoregulatory reactions of both hemispheres of the brain. Therefore, VRx can be used as a non-invasive cerebrovascular autoregulation index in the same way as PRx and can also provide information about the CA status encompassing all intracranial hemodynamics.

Accuracy, Precision, Sensitivity, and Specificity of Noninvasive ICP Absolute Value Measurements.

An innovative absolute intracranial pressure (ICP) value measurement method has been validated by multicenter comparative clinical studies. The method is based on two-depth transcranial Doppler (TCD) technology and uses intracranial and extracranial segments of the ophthalmic artery as pressure sensors. The ophthalmic artery is used as a natural pair of "scales" that compares ICP with controlled pressure Pe, which is externally applied to the orbit. To balance the scales, ICP = Pe a special two-depth TCD device was used as a pressure balance indicator. The proposed method is the only noninvasive ICP measurement method that does not need patient-specific calibration.

Association between the outcome of traumatic brain injury patients and cerebrovascular autoregulation, cerebral perfusion pressure, age, and injury grades.

BACKGROUND AND OBJECTIVE: The aim of this study was to explore the association of cerebrovascular autoregulation (CA) and optimal cerebral perfusion pressure (CPP) managing conditions with the outcome of traumatic brain injury (TBI) patients including additional information about the patients' age and grade of diffuse axonal injury (DAI). MATERIALS AND METHODS: The CA monitoring of 28 TBI patients was performed by using ICM+ software (Cambridge, UK). The CA status estimating pressure reactivity indexes (PRx) and CPP data were processed in order to obtain information on the patient-specific treatment conditions by calculating the optimal CPP. RESULTS: There was a negative correlation between the Glasgow outcome scale (GOS) score and PRx (r=-0.448 at hospital discharge and r=-0.402 after 6 months). The estimated threshold value PRx of >0.24 was associated with mortality. The correlation coefficients between the GOS score and the difference CPP-optimal CPP were 0.549 at hospital discharge and 0.484 after 6 months. The threshold value of CPP declination from ΔCPPopt per -6mmHg was associated with mortality. Poorer outcome was predicted for elderly TBI patients (aged >47 years) and patients having a DAI grade of 3. CONCLUSIONS: The association of the GOS score with CPP, CA impairment conditions, age and diffuse axonal injury (DAI) grade showed that the outcomes of TBI patients were associated with patient-specific CPP management and better outcomes were obtained for younger patients, for patients having lower DAI grade and for patients whose CPP was kept within the range from the optimal CPP to the optimal CPP+10mmHg.

Association of Severe Traumatic Brain Injury Patient Outcomes With Duration of Cerebrovascular Autoregulation Impairment Events.

BACKGROUND: Cerebrovascular autoregulation (CA) is an important hemodynamic mechanism that protects the brain against inappropriate fluctuations in cerebral blood flow in the face of changing cerebral perfusion pressure. Temporal CA failure is associated with worse outcomes in various acute neurological diseases. An integrative approach is presently used according to the existing paradigm for the association of series of temporal CA impairments with the outcomes of patients with traumatic brain injury (TBI). OBJECTIVE: To explore the influence of the duration of CA impairment events on severe TBI patient outcomes. Patient age was also included in the analysis of the prospectively collected clinical data. METHODS: CA monitoring included 33 prospective severe TBI patients. The pressure reactivity index [PRx(t)] was continuously monitored to collect information on the dynamics of CA status and to analyze associations between the duration of the longest CA impairment event and patient outcomes. RESULTS: The Glasgow outcome scale and the duration of the longest CA impairment were negatively correlated. The duration of autoregulation impairment significantly correlated with worse outcomes. Multidimensional representation of Glasgow outcome scale plots showed that better outcomes were obtained for younger patients (age < 47 years) and those whose longest CA impairment event was shorter than 40 minutes if PRx(t) was above 0.7 in the CA impairment event. CONCLUSION: Unfavorable outcomes for TBI patients are more significantly associated with the duration of the single longest CA impairment episode at a high PRx(t) value, rather than with averaged PRx(t) values or the average time of all CA impairment episodes. ABBREVIATIONS: ABP, arterial blood pressureABP(t), continuous reference arterial blood pressureCA, cerebrovascular autoregulationCBF, cerebral blood flowCPP, cerebral perfusion pressureGOS, Glasgow outcome scaleGOSHD, Glasgow outcome scale after hospital dischargeGOS6M, Glasgow outcome scale at 6 months after dischargeICP, intracranial pressureICP(t), continuously monitored intracranial pressureLCAI, longest CA impairmentoptCPP, optimal cerebral perfusion pressurePRx(t), pressure reactivity indexTBI, traumatic brain injury.

Noninvasive monitoring of cerebrovascular autoregulation response to resistance exercises.

BACKGROUND AND OBJECTIVE. A novel noninvasive monitor is presented by demonstrating its capabilities to perform the real-time estimation of dynamics in cerebrovascular autoregulation in athletes during their training. The aim was to explore the characteristics of human cerebrovascular autoregulation by performing the monitoring of cerebrovascular autoregulation responses to resistance exercises in healthy volunteer athletes. MATERIAL AND METHODS. Cerebrovascular autoregulation status was monitored in 20 amateur and 20 elite male athletes (weightlifters and bodybuilders) in the supine position at rest during and after the resistance exercises by using a novel noninvasive monitor "Vittamed." Blood pressure and heart rate were also measured noninvasively. During the exercises, the athletes lifted 50 kg and 80% of 1RM (repetition maximum) weights in a dynamic and static manner in separate tests. RESULTS. The cerebrovascular autoregulation reactivity index showed a temporal improvement in the cerebrovascular autoregulation status for almost all sportsmen after the exercises. No disturbances of cerebrovascular autoregulation response occurred in the weightlifters and amateur athletes after the static and dynamic exercises. However, an unstable status of cerebrovascular autoregulation was observed for the elite bodybuilders during the interval of 400 to 600 s after the exercises. CONCLUSIONS. The data of this study demonstrated significant differences in cerebrovascular autoregulation response to the resistance exercises between the elite bodybuilders and other subjects (amateurs and weightlifters) - a temporarily unstable status of cerebrovascular autoregulation was observed in the group of elite bodybuilders. This study also demonstrated the applicability of the noninvasive device for exploring the physiology of cerebrovascular autoregulation mechanism in elite athletes and healthy volunteers.