|Year : 2022 | Volume
| Issue : 3 | Page : 167-170
Autoregulation disturbance events correlate with history of loss of consciousness in mild traumatic brain injury patients
Ida Bagus Krisna Jaya Sutawan, Tatang Bisri, I Putu Pramana Suarjaya, I Made Prema Putra, Christopher Ryalino
Department of Anesthesiology and Intensive Care, Faculty of Medicine, Udayana University, Bali, Indonesia
|Date of Submission||13-Jan-2022|
|Date of Decision||21-Apr-2022|
|Date of Acceptance||28-Apr-2022|
|Date of Web Publication||18-May-2022|
Department of Anesthesiology and Intensive Care, Faculty of Medicine, Udayana University, Jl. PB Sudirman, Denpasar 80232, Bali
Source of Support: None, Conflict of Interest: None
Introduction: Cerebral autoregulation disturbance may compromise cerebral blood flow, thereby increasing the risk of hypoperfusion, which increases the risk of loss of consciousness (LOC). Transient hyperemic response test (THRT) using transcranial Doppler (TCD) can be used to assess cerebral autoregulation disturbance. The goal of this study was to assess the relationship between impaired cerebral autoregulation assessed using TCD and a history of LOC in patients with a mild head injury. Patients and Methods: This study was a comparative analytic study with unpaired data and cross-sectional design that involved 73 people divided into two groups. Group A (36 subjects) consists of mild brain injury patients with a history of LOC, and Group B (37 subjects) consists of mild brain injury patients without a history of LOC. THRT was assessed using TCD by identifying the absence (negative result) in flow velocity increase upon applying pressure on ipsilateral carotid artery. We employed the chi-square and logistic regression tests to assess any correlation between variables. A value of P < 0.05 was considered significant. Results: Approximately 93% of subjects who experienced LOC also showed negative THRT results. We found a statistically significant relationship (P < 0.001) between the history of LOC and THRT. In the logistic regression test, we found that age, gender, and hematocrit were not statistically related to negative THRT results. Conclusion: There is a statistically significant relationship between cerebral autoregulation disturbance and decreased consciousness event in mild head injury patients.
Keywords: Brain injuries, cerebrovascular regulation, consciousness, logistic models
|How to cite this article:|
Sutawan IB, Bisri T, Suarjaya I P, Putra I M, Ryalino C. Autoregulation disturbance events correlate with history of loss of consciousness in mild traumatic brain injury patients. Bali J Anaesthesiol 2022;6:167-70
|How to cite this URL:|
Sutawan IB, Bisri T, Suarjaya I P, Putra I M, Ryalino C. Autoregulation disturbance events correlate with history of loss of consciousness in mild traumatic brain injury patients. Bali J Anaesthesiol [serial online] 2022 [cited 2022 Aug 10];6:167-70. Available from: https://www.bjoaonline.com/text.asp?2022/6/3/167/345474
| Introduction|| |
Clinically, patients with mild traumatic brain injury (mTBI) present with a Glasgow Coma Scale (GCS) of 13–15. They may have a history of loss of consciousness (LOC), amnesia, and memory disturbance. Head injury is defined as a complex pathophysiological process that affects the brain that is caused by trauma due to biomechanical forces., Brain tissue is very sensitive to hypoxia and ischemia, therefore regulation of cerebral blood flow plays an important role. Cerebral autoregulation is the intrinsic ability of the cerebellum to maintain a constant cerebral blood flow against changes in systemic blood pressure.
LOC is closely related to the suppression or disturbance in the brain area that regulates consciousness, whether it is due to hypoperfusion or ischemia of the cerebral hemispheres or the reticular activating system (RAS). Impaired cerebral autoregulation increases morbidity and poor outcomes after head injury and increases the risk of secondary brain injury.,, Anesthesia procedures, as a part of management of mTBIs, are currently conducted similarly between patients who presented with or without a history of LOC. However, the history of LOC can indicate a more severe primary brain injury which can also increase the possibility of cerebral autoregulation disorders because both occur as a result of primary brain injury.
Until now, there is no gold standard to assess the presence of autoregulation disorders. One test that can assess the presence of autoregulation disturbance using TCD is the transient hyperemic response test (THRT)., To date, no studies have investigated the association between the incidence of autoregulation disturbances evaluated by THRS using TCD and the history of LOC. The goal of this study is to assess the relationship between impaired cerebral autoregulation assessed using TCD and a history of LOC in patients with a mild head injury.
| Patients and Methods|| |
This was an unpaired, cross-sectional, comparative analytic study conducted from June to August 2018 by total inclusive sampling. The study protocol was approved by the Committee of Ethical Clearance of Udayana University (registry number 1387/UN.14.2.2/PD/KEP/2018 dated February 1, 2018). All subjects involved in this study, or their legal guardian, have provided written informed consent to be included in this study.
Inclusion criteria included mTBI patients with a GCS of 13–15 who came to the Emergency Department of Sanglah General Hospital (Bali, Indonesia) for the period with brain trauma occurred within 24 h upon arrival, aged 18–40 years, normal hemoglobin value, and normal blood sugar level. Exclusion criteria included the presence of increased intracranial pressure (ICP) signs or symptoms, history taking of whether the subject was unconscious was inconclusive, any concussion-related abnormalities from the computed tomography (CT) scan, history of unexplained recent fainting, history of orthostatic hypotension, history of cardiac arrhythmias, history of structural heart disease, history of epilepsy, and history of stroke.
The subjects were randomly assigned to one of two groups: Group A (36 subjects), consisting of mTBI patients with a history of LOC, or Group B (37 subjects), consisting of mTBI patients without a history of LOC. The history of LOC is assessed by taking anamnesis from the subject or a person who witnessed the accident (i.e., family, bystander, emergency responder).
The THRT is carried out by insonating to get an overview of the baseline velocity on the middle cerebral artery (MCA) using transcranial Doppler’s (TCD) ultrasound, then pressing the ipsilateral carotid artery for 3 ss while still doing the insonation on the ipsilateral MCA. After releasing the pressure, we evaluated a transient hyperemic response in the form of an increase in flow velocity (FV) above the baseline. This temporary increase in FV is indicated by F3. If the transient hyperemic response does not appear, it is considered to have an autoregulation disturbance. For the purpose of this study, this absence in response will be interpreted as negative THRT result.
We used IBM SPSS Statistics (IBM Corp. Released 2017. IBM SPSS Statistics for Windows, Version 25.0. Armonk, New York: IBM Corp.) for data analysis. We employed the chi-square and logistic regression tests to assess any correlation between variables. A value of P < 0.05 was considered significant.
| Results|| |
In this study, the characteristics of research subjects were differentiated based on age, gender, hematocrit level, partial pressure of carbon dioxide (pCO2), body temperature, and blood sugar level [Table 1]. The chi-square test was performed to assess whether there was an association between THRT and the history of LOC. In this test, a statistically significant relationship was found [Table 2] between the history of LOC and the results of THRS examination (P < 0.001). In the logistic regression test, we found that age, gender, and HCT were not statistically related to negative THRT results [Table 3].
|Table 2: Correlation between transient hyperemic response test and history of unconsciousness|
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|Table 3: Logistic regression test between variables and history of unconsciousness|
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| Discussion|| |
Brain metabolism relates very exclusively to the oxidation of glucose that can only be carried out with adequate amounts of oxygen. So, the brain needs a lot of oxygen supply, approximately 25% of all oxygen consumed by the body. To meet this need for oxygen, flow to the brain is sent through several arteries. Among them are a pair of large arteries, namely the right and left internal carotid arteries, a pair of vertebral arteries, and only a small part of which is supplied by the anterior spinal artery to the brainstem. Cerebral blood flow is affected by several factors which can be broadly divided into factors affecting cerebral perfusion pressure and factors affecting cerebral blood vessel diameter (cerebral metabolism, carbon dioxide and oxygen, cerebral artery autoregulation, and neurohumoral factors).
Cerebral autoregulation is the intrinsic ability of cerebral vasculature to maintain constant cerebral blood flow against changes in systemic blood pressure. Conventionally, autoregulation can be divided into two: static autoregulation and dynamic autoregulation., Cerebral autoregulation can be impaired in many pathological conditions including patients with brain tumors, subarachnoid hemorrhage, stroke, or head injury. Brain autoregulation can be impaired in some degree of head injury, even in mild head injuries or in head injuries with normal ICP and mean arterial blood pressure (MABP) values. Several animal studies have shown that autoregulation disorders can still occur even though cerebral perfusion pressure and blood flow to the brain are still in normal conditions., Noninvasively, cerebral autoregulation can be evaluated with TCD. Evaluation of dynamic autoregulation can be done in several ways including carotid artery suppression (THRT), valsalva maneuver, head up-tilt, and leg-cuff test.
Primary brain injury that occurs at the time of head injury will cause damage to brain tissue and other intracranial structures. One of them is a disturbance in cerebral autoregulation mechanism, which leads to impaired blood flow regulation to the brain, thereby increasing the possibility of compromised brain perfusion. The main common cause leading to decreased consciousness is insufficient cerebral perfusion with a critical reduction in blood flow to the Reticular Activating System. The cerebral circulation has an autoregulatory system that keeps cerebral blood flow constant at various systemic blood pressures. Normally, if blood pressure is decreased, autoregulation reacts with a decrease in cerebral vascular resistance, in an attempt to prevent cerebral hypoperfusion.
Several studies conducted in several countries have shown an association between autoregulatory disorders and head injuries, even minor ones. Strebel et al.’s study showed impaired cerebral autoregulation in patients with a mild head injury. In this study, examinations were performed three times in each patient: initial autoregulation measurements during stable fentanyl-nitrous oxide anesthesia, second and third measurements during low-dose and high-dose anesthesia administered to the patient. Autoregulation was tested by increasing mean systemic blood pressure from 80 mm Hg to 100 mm Hg using a phenylephrine drip while recording the FV from the MCA using TCD ultrasonography. However, in this study, the relationship between impaired autoregulation and decreased consciousness was not investigated. In our study, TCD examination was only performed once. Our study found a statistically significant association between impaired autoregulation and decreased level of consciousness (P < 0.05). The results of the study that we obtained through logistic regression showed that confounding variables, such as age (P = 0.983), gender (P = 0.191), and HCT (P = 0.052), did not affect the validity of the results of this study. Negative THRS (P = 0.003), which is a marker of impaired autoregulation, also showed a statistically significant association with the incidence of LOC in patients with head injury.
There are very limited studies examining the association between impaired autoregulation and LOC in patients with head injuries. One of the reasons is that there is no gold standard examination in assessing autoregulation disorders. Therefore, further research in this regard is needed.
Several literatures with an observational design suggest that impaired cerebral autoregulation is associated with a poorer patient prognosis. Thus, optimizing cerebral blood flow by targeting individual arterial blood pressure (ABP) has the potential to improve outcomes. A clinical trial with pigs as experimental animals was used to measure the hemodynamic response of the wattle arteriole, the main site of control barrier function (CBF) control, based on changes in red blood cell diameter and velocity. This method is considered to be able to measure cerebral autoregulation quantitatively.
| Conclusion|| |
There is a statistically significant relationship between cerebral autoregulation disturbance as measured by THRT with TCD on decreased consciousness in head injury patients. This research can be used as a pilot study for further research. It is hoped that the evaluation of regulatory disorders can be carried out clinically so that the prognosis of head injury patients undergoing surgery is better.
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Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3]