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CLINICAL INVESTIGATION
Year : 2008  |  Volume : 52  |  Issue : 6  |  Page : 823 Table of Contents     

Controversial Issues in Neuroanaesthesia and Their Current Practice in India-A Questionnaire Survey


1 Assistant Professor, India
2 Senior Resident, Department of Neuroanaesthesiology, Neurosciences Center, 7th floor, All India Institute of Medical Sciences, New Delhi-110029, India
3 Professor, Department of Neuroanaesthesiology, Neurosciences Center, 7th floor, All India Institute of Medical Sciences, New Delhi-110029, India

Date of Acceptance25-Aug-2008
Date of Web Publication19-Mar-2010

Correspondence Address:
Hemanshu Prabhakar
Department of Neuroanesthesiology, Neurosciences Center, 7th floor, All India Institute of Medical Sciences, New Delhi-110029
India
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Source of Support: None, Conflict of Interest: None


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To address the practice of various controversial issues in neuroanaesthesia practice in India, a questionnaire survey was conducted during the Annual Conference of Indian Society of Neuroanaesthesiology and Critical Care (ISNACC), held in Hyderabad this year in February 2008. The aim of the survey was to assess the views of the neuroanaesthetists on these issues and its influence in their clinical practice.
A simple questionnaire comprising of eight questions was prepared related to the various controversies in neuroanaesthesia. Participants were asked to fill the questionnaire and return before the end of conference. All the questionnaires were distributed in hand and collected personally.
The response rate was 66.25% from the nearly 160 delegates. The response was received from nearly an equal number of practitioners, both in the government and corporate sectors. Most of the respondents shared a neutral opinion on the controversies in neuroanaesthesia.
New challenges are being faced by anaesthetists with evolution of neurosurgical practice. Various controver­sies have led to more research in this field. Although the awareness exists among Indians, the practice continues at many centres. Multi-centric trials to address such issues may prove beneficial.

Keywords: Neuroanaesthesia; Controversies; Questionnaire survey


How to cite this article:
Prabhakar H, Sharma M, Jain V, Ali Z, Bithal PK, Dash HH. Controversial Issues in Neuroanaesthesia and Their Current Practice in India-A Questionnaire Survey. Indian J Anaesth 2008;52:823

How to cite this URL:
Prabhakar H, Sharma M, Jain V, Ali Z, Bithal PK, Dash HH. Controversial Issues in Neuroanaesthesia and Their Current Practice in India-A Questionnaire Survey. Indian J Anaesth [serial online] 2008 [cited 2020 Sep 18];52:823. Available from: http://www.ijaweb.org/text.asp?2008/52/6/823/60695


   Introduction Top


As 'Neuroanaesthesia' continues to expand and develop, the basic principles remain unchanged - pro­vision of optimal operative conditions, maintenance of cerebral perfusion pressure (CPP), and cerebral oxy­genation. However, despite advances in drugs and monitoring modalities, many controversies remain re­garding the clinical practice of neuroanaesthesia the choice of anaesthetic agent and fluids, and intraopera­tive hypothermia. [1],[2],[3],[4],[5] To address some of these issues such as the use of nitrous oxide, intraoperative hypoten­sion and anaesthetic technique for carotid endarterec­tomy [6],[7],[8],[9],[10],[11],[12] , we conducted a survey on the practice amongst the neuroanaesthetists in India. The aim of the survey was only to find out the opinion and preference on the controversial topics in the neuroanaesthesia prac­tice of the anaesthetists.


   Methods Top


A questionnaire was prepared asking questions on the various controversial issues in neuroanaesthesia practice. We surveyed all anaesthetists practicing neuroanaesthesia who attended the 9 th Annual Confer­ence of Indian Society of Neuroanaesthesiology and Critical Care, held at Hyderabad, India, from 8 th to 10th February 2008. A questionnaire was distributed randomly to the delegation of about 160 persons. The questionnaire [Appendix 1] included the practice of [Additional file 1] induced hypotension, hypothermia, use of nitrous ox­ide, preference for inhalational versus intravenous ana­esthesia, choice of fluids, and anaesthetic technique for carotid endarterectomy (CEA). Participants were asked to fill the questionnaire and return before the end of conference. Respondents were asked to mark single answer for each question except the one on fluids choice, where more than one answers were accept­able. The respondents were also required to fill their gender, place of work and years of clinical experience.

This survey is not a comparative study where sta­tistical tests can be applied. However, results are ex­pressed as mean (range), number or percentage.


   Results Top


A total of 106 replies were received giving a re­sponse rate of 66.25%. Two respondents were cur­rently practicing outside India and their replies were not analysed further. The results are based on the re­maining 104 respondents. There were 64 male and 40 female respondents working in government and cor­porate sectors of the country. The division in the work­ing sector was nearly equal, with 60 working in gov­ernment hospitals and the remaining 44 in various cor­porate and private sectors. The duration of clinical prac­tice of the respondents was 12.8 (5 - 29) years. The demographics are tabulated in [Table 1]. Majority of re­spondents [76.9%] favoured combined anaesthesia as compared to 9.6% respondents who preferred inhala­tional anaesthetic techniques and eight respondents [7.7%] practiced intravenous method of anaesthesia. A small number of respondents [5.8%] did not dis­close their preference and left the question unanswered. Overall results revealed an inclination of the anaesthetists towards combined anaesthesia technique. [Figure 1] Our survey revealed that induced hypothermia was not preferred by majority of the respondents [44.2%] and was never practiced by them. Nearly an equal number of participants [42.3%] informed that they occasionally induced hypothermia to their patients. This was mostly passive as a result of the operating room temperature. No active measures were taken by them to reduce temperature in their patients. Twelve respon­dents [11.5%] frequently induced hypothermia to their patients during intraoperative period. The trend among Indian neuroanaesthetists was mostly towards mainte­nance of normothermia. [Figure 2] Our survey revealed occasional practice of induced hypotension in the in­traoperative period [55.8%]. While 25% of respon­dents claimed to be practicing induced hypotension fre­quently, 19.2% never favoured the technique. [Figure 3]. The results of our survey revealed that majority of the anaesthetists [55.8%] used general anaesthesia for CEA as compared to only 21.2% who used regional blocks and local anaesthesia. Around 23% of respondents admitted that CEA was not performed in their centre. [Figure 4] However, our survey shows that a vast major­ity of respondents [76.9%] believed in using both inva­sive and non-invasive monitoring techniques. Nearly an equal number preferred invasive and non-invasive meth­ods; 9.6% and 7.8% respectively. The question was not answered by 6 respondents [5.7%]. [Figure 5] Normal saline remained the fluid of choice by 96 % of our respondents. Many participants also gave additional choice for fluids other than normal saline. Ringer's lac­tate solution was routinely used by 61.5% of anaesthetists in their neuroanaesthesia practice. Dex­trose 5% was undoubtedly not the favoured fluid and no respondent admitted its use in their practice. Ten respondents out of 110 used Dextrose-normal saline solution along with normal saline. [Figure 6] Our respon­dents frequently used nitrous oxide and claimed it to be an indispensable part of their anaesthetic practice. Ni­trous oxide was frequently used by 67% and occa­sionally by 21%. Six respondents had completely stopped using nitrous oxide in their neurosurgical an­aesthetic practice. The question was left unanswered by 5% of the respondents. [Figure 7] In our survey, we also enquired whether any sort of cerebral protective measures were being used intraoperatively, especially during aneurysmal surgery. To this majority of the re­spondents answered positively [84.6%]. Around 4% of respondents said that they did not use any cerebro­protective measures and maintained routine anaesthe­sia. The question was not answered by 11.5% partici­pants, mostly by those in whose centre the surgery for intracranial aneurysm was not being performed. What agent was being preferred for cerebral protection was not asked as it was beyond the scope of our survey. [Figure 8] However, on enquiring, it was found that most respondents who used cerebro-protective measures favoured the use of thiopentone sodium. Some respon­dents even suggested using propofol and mannitol in­traoperatively as their strategy for cerebral protection.


   Discussion Top


Controversies regarding the provision of anaes­thesia for intracranial neurosurgery remain, with no ideal technique identified. [1] Despite the theoretical benefits of intravenous agents, volatile agents remain popular. In a study comparing desflurane, isoflurane and sevoflurane in a porcine model of intracranial hyper­tension, at equipotent doses and normocapnia, cere­bral blood flow (CBF) and intracranial pressure (ICP) were greatest with desflurane and least with sevoflurane. [2] The same authors also confirmed that sevoflurane also caused least vasodilation. [3] In two separate studies, isoflurane was seen to impair autoregulation, although reversible with hyperventilation, while autoregulation was virtually intact with sevoflurane 1 - 1.2 % at normocapnia. [4],[5] Although large studies may be needed, sevoflurane appears to be the most suitable volatile agent for neuroanaesthesia practice. The detrimental effects of nitrous oxide are well documented. [6] How­ever, most of the studies can be directly extrapolated to clinical practice where other agents influence the ef­fects of nitrous oxide. Interesting finding in a study on 700 patients was that the drugs used for induction and maintenance of anaesthesia, were not independent risk factors for intraoperative brain swelling. ICP at the start of surgery, degree of midline shift on computed tomo­graphic scan, and the histological diagnosis of glioblas­toma or metastasis were the risk factors. [7]

Cerebral ischemia and hypoxia can occur in a variety of perioperative circumstances and controversy surrounds the role of hypothermia in cerebral protec­tion. While hypothermia initially showed beneficial ef­fects in survivors of cardiac arrest and hypoxic insults, [8] its application was not favoured in years to come. This was probably due to the lack of efficacy and the logis­tics. There is no doubt that deep hypothermia (18 - 22°C) is highly neuroprotective but a large trial on pa­tients with traumatic brain injury has shown no improved outcome after mild hypothermia. [9] The randomized pro­spective International Hypothermia Aneurysm Trial did not find a beneficial effect of induced mild intraopera­tive hypothermia (33°C) during aneurysm surgery. [10] In the course of defining hypothermia efficacy, it has be­come apparent that hyperthermia has adverse effects on post-ischemic brain. Therefore, aggressive treatment of hyperthermia should always be considered.

Induced hypotension was once favoured during intraoperative aneurysm surgery at the time of clipping. However, it is no longer used routinely because it may critically impair overall cerebral perfusion, especially in presence of hypovolemia, and has been associated with adverse outcome and a higher incidence of severe ce­rebral vasospasm. [11]

Another debate is on the superiority of regional anaesthesia or general anaesthesia in the management of CEA. An awake patient is the best monitor for CEA. There are reports of reduction in intraoperative shunt­ing and perioperative stroke and the duration of hospi­tal stay after regional anaesthesia than general anaes­thesia for CEA. [12] Local anaesthesia also offers clinical and cost advantages over general anaesthesia. How­ever, an uncooperative patient may require general ana­esthesia, which requires optimal cerebral monitoring.

Less invasive monitoring strategies have recently gained some acceptance in neurosurgical practice. It has been shown that because of hazards and compli­cation of invasive monitoring, non-invasive monitors that are equally sensitive, safe and easy to learn are pre­ferred. [13]

The intraoperative fluid management of neurosur­gical patients presents special challenges for the anaes­thetist. The movement of water between the vascula­ture and the brain's extracellular space is driven prima­rily by the presence of osmotic gradients. Clinically these gradients are established by administration of either hyperosmolar (mannitol) or hypoosmolar (5% dextrose) solutions. In the brain (unlike peripheral tissue) plasma oncotic pressure has little impact on cerebral edema formation. Attempts to minimize cerebral edema for­mation with fluid restriction are unlikely to be success­ful and, if overzealously pursued, may lead to haemodynamic instability. Although no single intrave­nous solution is best suited for the neurosurgical patient who is at risk for intracranial hypertension, the use of isoosmolar crystalloids is widely accepted and can be justified on scientific basis. [14]

There has been a decline on the use of nitrous oxide over the past few years, mainly due to the health related hazards of the gas and other associated com­plications, like, pneumocephalus, air embolism, neuro­pathies etc.

The response from our surveys does suggest that there is awareness among the anaesthetists regarding the controversies in neuroanaesthesia. Most prefer to use combined anaesthetic techniques, maintain normo­thermia in their patients, at times induce hypotension, and use both invasive and non-invasive techniques of monitoring. The preferred fluid remains normal saline and most have no reservations on use of nitrous oxide. CEA is generally performed under general tracheal ana­esthesia and majority use some cerebral protective measures intraoperatively in their patients. The last de­cade has seen a rapid expansion of our knowledge in clinical neurosciences. New challenges are being faced by anaesthetists with evolution of neurosurgical prac­tice. The evolving clinical practices and monitoring modalities have helped in improved patient outcome. At the same time, controversies pertaining to drugs, intraoperative fluid management, and intraoperative anaesthetic techniques have resulted in more clinical trials in search of appropriate solutions. It is possible that a repeat survey in future would give us a better understanding of the changing trends among the neuroanaesthesiologists in India.

 
   References Top

1.Petersen KD, Landsfeldt U, Cold GE, et al. Intracranial pressure and cerebral haemodynamics in patients with cerebral tumours: a randomised prospective study of patients subjected to craniotomy in propofol-fentanyl, isoflurane-fentanyl, or sevoflurane-fentanyl anaesthe­sia. Anesthesiology 2003; 98: 329 - 336.  Back to cited text no. 1  [PUBMED]  [FULLTEXT]  
2.Holmstrom A, Akeson J. Desflurane increases the in­tracranial pressure more and sevoflurane less than isoflurane in pigs subjected to intracranial hyperten­sion. J Neurosurg Anesthesiol 2004; 16: 136 - 143.  Back to cited text no. 2      
3.Holmstrom A, Akeson J. Sevoflurane induces less cere­bral vasodilation than isoflurane at the same A - line autoregressive index level. Acta Anaesthesiol Scand 2005; 49: 16 - 22.  Back to cited text no. 3      
4.McCulloch TJ, Boesel TW, Lam AM. The effect of hy­pocapnia on autoregulation of cerebral blood flow dur­ing administration of isoflurane. Anesth Analg 2005;100: 1463 - 1467.  Back to cited text no. 4  [PUBMED]  [FULLTEXT]  
5.Rozet I, Vavilala MS, Lindley AM, et al. Cerebral auto­regulation and CO 2 reactivity in anterior and posterior circulation during sevoflurane anaesthesia. Anesth Analg 2006; 102: 560 - 564.  Back to cited text no. 5  [PUBMED]  [FULLTEXT]  
6.Hancock SM, Nathanson MH. Nitrous oxide or remifentanil for the at risk brain. Anaesthesia 2004; 59: 313 - 315.  Back to cited text no. 6  [PUBMED]  [FULLTEXT]  
7.Rasmussen M, Bundgaard H, Cold GE. Craniotomy for supratentorial brain tumors: risk factors for brain swell­ing after opening the dura mater. J Neurosurg 2004; 101: 621 - 626.  Back to cited text no. 7  [PUBMED]  [FULLTEXT]  
8.Benson DW, Williams GR Jr, Spencer FC, Yates AJ. The use of hypothermia after cardiac arrest. Anesth Analg 1959; 38: 423 - 438.  Back to cited text no. 8  [PUBMED]  [FULLTEXT]  
9.Clifton GL, Miller ER, Choi SC, et al. Lack of effect of induction of hypothermia after acute brain injury. N Eng J Med 2001; 344: 556 - 563.  Back to cited text no. 9      
10.Todd MM, Hindman BJ, Clarke WR, Torner JC. The in­traoperative hypothermia for aneurysm surgery trial (IHAST) Investigators. Mild hypothermia during sur­gery for intracranial aneurysm. N Eng J Med 2005; 352: 135 - 145.  Back to cited text no. 10      
11.Chang HS, Hongo K, Nakagawa H. Adverse effects of limited hypotensive anaesthesia on the outcome of pa­tients with subarachnoid hemorrhage. J Neurosurg 2000; 92: 971 - 975.  Back to cited text no. 11  [PUBMED]  [FULLTEXT]  
12.Mofidi R, Nimmo AF, Moores C, Murie JA, Chalmers RT. Regional versus general anaesthesia for carotid endartectomy: impact of change in practice. Surgeon 2006; 4: 158 - 162.  Back to cited text no. 12      
13.Russel JA. New technologies for the new millennium. Annals of New York Academy of Sciences. 2001; 939: 101 - 113.  Back to cited text no. 13      
14.Zornow MH, Scheller MS. Intraoperative fluid manage­ment during craniotomy. In: Cottrell JE, Smith DS eds. Anaesthesia and neurosurgery. 4th ed. Mosby Inc, St Louis 2001; 237 - 249.  Back to cited text no. 14      


    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8]
 
 
    Tables

  [Table 1]



 

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