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Table of Contents
ORIGINAL ARTICLE
Year : 2022  |  Volume : 6  |  Issue : 3  |  Page : 167-170

Autoregulation disturbance events correlate with history of loss of consciousness in mild traumatic brain injury patients


Department of Anesthesiology and Intensive Care, Faculty of Medicine, Udayana University, Bali, Indonesia

Date of Submission13-Jan-2022
Date of Decision21-Apr-2022
Date of Acceptance28-Apr-2022
Date of Web Publication18-May-2022

Correspondence Address:
Christopher Ryalino
Department of Anesthesiology and Intensive Care, Faculty of Medicine, Udayana University, Jl. PB Sudirman, Denpasar 80232, Bali
Indonesia
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/bjoa.bjoa_13_22

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  Abstract 

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 Top


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.[1],[2] 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.[2]

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).[3] Impaired cerebral autoregulation increases morbidity and poor outcomes after head injury and increases the risk of secondary brain injury.[4],[5],[6] 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).[7],[8] 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 Top


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 Top


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 1: Characteristics of the subjects

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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 Top


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.[2] Conventionally, autoregulation can be divided into two: static autoregulation and dynamic autoregulation.[9],[10] 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.[11] 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.[12],[13] 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.[14]

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.[5] 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 Top


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.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Zamzami N, Fuadi I, Nawawi A. Angka Kejadian dan Outcome Cedera Otak di RS. Hasan Sadikin Bandung Tahun 2008–2010. J Neuroan Indon 2013;2:89-94.  Back to cited text no. 1
    
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Len TK, Neary JP. Cerebrovascular pathophysiology following mild traumatic brain injury. Clin Physiol Funct Imaging 2011;31: 85-93.  Back to cited text no. 2
    
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Blyth BJ, Bazarian JJ. Traumatic alterations in consciousness: Traumatic brain injury. Emerg Med Clin North Am 2010;28: 571-94.  Back to cited text no. 3
    
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Sviri GE, Newell DW. Cerebral autoregulation following traumatic brain injury. Blood Pressure 2010;9:11.  Back to cited text no. 4
    
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Strebel S, Lam AM, Matta BF, Newell DW. Impaired cerebral autoregulation after mild brain injury. Surg Neurol 1997;47:128-31.  Back to cited text no. 5
    
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Jünger EC, Newell DW, Grant GA, Avellino AM, Ghatan S, Douville CM, et al. Cerebral autoregulation following minor head injury. J Neurosurg 1997;86:425-32.  Back to cited text no. 6
    
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Matta B, Czosnyka M. Transcranial Doppler ultrasonography in anesthesia and neurosurgery. In: Cottrell JE, Patel P, editors. Neuroanesthesia. 6th ed. New York: Elsevier; 2017. p. 127-41.  Back to cited text no. 7
    
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Sutawan IBKJ, Saleh SC, Bisri T. Konsep dasar transcranial Doppler (TCD) untuk neurocritical care. JNI 2017;6:195-204.  Back to cited text no. 8
    
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Toth P, Szarka N, Farkas E, Ezer E, Czeiter E, Amrein K, et al. Traumatic brain injury-induced autoregulatory dysfunction and spreading depression-related neurovascular uncoupling: Pathomechanisms, perspectives, and therapeutic implications. Am J Physiol Heart Circ Physiol 2016;311:H1118-31.  Back to cited text no. 9
    
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Folino AF. Cerebral autoregulation and syncope. Progress in Cardiovascular Diseases 2007;50:49-80.  Back to cited text no. 10
    
11.
Rangel-Castilla L, Gasco J, Nauta HJ, Okonkwo DO, Robertson CS. Cerebral pressure autoregulation in traumatic brain injury. Neurosurg Focus 2008;25:E7.  Back to cited text no. 11
    
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Czosnyka M, Smielewski P, Piechnik S, Steiner LA, Pickard JD. Cerebral autoregulation following head injury. J Neurosurg 2001;95:756-63.  Back to cited text no. 12
    
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Kirkness CJ, Mitchell PH, Burr RL, Newell DW. Cerebral autoregulation and outcome in acute brain injury. Biol Res Nurs 2001;2:175-85.  Back to cited text no. 13
    
14.
Naqvi J, Yap KH, Ahmad G, Ghosh J. Transcranial Doppler ultrasound: A review of the physical principles and major applications in critical care. Int J Vasc Med 2013;2013:629378.  Back to cited text no. 14
    



 
 
    Tables

  [Table 1], [Table 2], [Table 3]



 

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Abstract
Introduction
Patients and Methods
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