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Year : 2007  |  Volume : 51  |  Issue : 5  |  Page : 405 Table of Contents     

A Survey on Use of Nitrous Oxide in Current Anaesthetic Practice in India

1 M.D, Senior Resident, Department of Neuroanaesthesiology, All India Institute of Medical Sciences, New Delhi-110029, India
2 M.D, Assistant Professor, Department of Neuroanaesthesiology, All India Institute of Medical Sciences, New Delhi-110029, India
3 M.D, Professor, Department of Neuroanaesthesiology, All India Institute of Medical Sciences, New Delhi-110029, India

Date of Acceptance04-Aug-2007
Date of Web Publication20-Mar-2010

Correspondence Address:
H H Dash
(Prof. & Head) Department of Neuroanaesthesiology, 7th floor, Neurosciences Centre, All India Institute of Medical Sciences, New Delhi -110029
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Source of Support: None, Conflict of Interest: None

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In anaesthetic practice, exposure to a hazardous substance should be eliminated or controlled where practicable. Over the past few years, the use of nitrous oxide has become debatable. To assess the current anaesthetic practice in India on the use of nitrous oxide, a total of 400 questionnaires constituted by 15 questions on three topics- use of nitrous oxide, medical air and TIVA(total intravenous anaesthesia)- were distributed.
Anaesthesiologists were selected randomly and requested to fill up the questionnaire.
Of the 400 questionnaires, 40 questionnaires were discarded due to incomplete answer, leaving a total of 360 valid returned questionnaires, a 90% response rate. 27.22% respondents stated that the use of nitrous oxide had decreased .When medical air was available, 66.67% felt that they would use it frequently. A total of 214 (59.44%) stated that they used total intravenous anaesthesia occasionally.
The results showed that although anaesthesiologists had reduced their use of nitrous oxide, this was due to medical considerations rather than concerns over health and pollution issues arising from the use of nitrous oxide.

Keywords: Nitrous oxide, Occupational hazard, Anaesthesiologists, Questionnaire survey

How to cite this article:
Mitra JK, Jain V, Sharma D, Prabhakar H, Dash H H. A Survey on Use of Nitrous Oxide in Current Anaesthetic Practice in India. Indian J Anaesth 2007;51:405

How to cite this URL:
Mitra JK, Jain V, Sharma D, Prabhakar H, Dash H H. A Survey on Use of Nitrous Oxide in Current Anaesthetic Practice in India. Indian J Anaesth [serial online] 2007 [cited 2021 Apr 21];51:405. Available from: https://www.ijaweb.org/text.asp?2007/51/5/405/61171

   Introduction Top

The role of nitrous oxide as an anaesthetic agent has been debated time and again ever since its first use. The liberal use of nitrous oxide in clinical anaesthetic procedures has generated concern regarding its utility versus its ominous capacity to pollution [1],[2],[3],[4] resulting in potential occupational hazard. The problem of addiction [5],[6] and development of myeloneuropathy [7],[8] with use of nitrous oxide has also been reported. The introduction of new inhalational anaesthetic compounds has led to the exit of irritant ones like ether, chloroform and methoxy­flurane, which are no longer used in 'modern anaesthe­sia practice'. Nitrous oxide, however, has managed to survive, and is the only anaesthetic agent which has trav­elled down the history of anaesthesia without losing in actuality. Before giving any judgement on the future of nitrous oxide, we must assess the disadvantages of the gas and see if there are any ways to overcome them.

We tried to assess the usage of nitrous oxide in present day anaesthetic practice in India - increased, decreased or remained the same over the past 5 years - since there has been a greater practice of total intrave­nous anaesthesia and recent increased provision for medical air on anaesthetic machines.

A questionnaire was circulated to ascertain whether anaesthesiologist in the Indian subcontinent was con­cerned about pollution levels and whether their anaes­thetic practice and use of nitrousoxide had changed over the past 5 years. Current trends of use of other inhala­tional anaesthetics, opioids, total intravenous anaesthe­sia (TIVA) and medical air were also assessed.

   Methods Top

The questionnaire was developed asking 15 ques­tions in three areas. These examined the use of nitrous oxide, to what extent medical air is utilized and whether it is used with nitrous oxide, and the current usage of TIVA. A gender question was included in order to as­certain whether the female-oriented health issues asso­ciated with pollution exposure in operating theatre, were influencing attitude to nitrousoxide usage. A copy of the questionnaire is given as an appendix.

A total of 400 questionnaires were distributed in the Annual Conference of Indian Society of Anaesthesiologists (ISACON-2005), held at Kolkata, West Bengal, India from 26 th -30 th December 2005. Anaesthesiologists were selected randomly and requested to fill up the questionnaire during the recess hours of the conference. The filled questionnaires were duly collected after some time. The group to be studied included con­sultants guaranteed to have at least 5 years experience in anaesthesia after 3 years of their training in the sub­ject (MD or DNB qualification) .

   Results Top

A total of 400 questionnaires were distributed: of these 40 were discarded due to incomplete answer, leav­ing a total of 360 valid returned questionnaires, a 90% response rate. Of the returned questionnaires, 280(77.77%) were male and 80 (22.23%) female. The minimum number of years spent in clinical anaesthesia was 5 years, with a maximum of 39 years; 92(25.56%) had more than 15 years of experience. 92 (25.56%) re­sponders were from private institutions

   Nitrous oxide Top

In response to question-1, 84.44% stated that they used nitrous oxide frequently, with 12.22% using it oc­casionally, and only 3.89% stating that they never used the gas. Doctors working in private institutions used nitrous oxide more frequently (86.95%) when compared to the whole group. When asked about the last 5 years (question 2), 234(65%) of respondents stated that their use of nitrous oxide had stayed the same, with 27.22% stating that their use had decreased. 250 responders (69.44%) (question 3) stated that they avoided using ni­trous oxide for particular operations such as bowel sur­gery, surgeries related to ear and eye, sitting position and cardiac procedures. 51.67% always used close cir­cuit with circle absorber, while 11.11% never used close circuit with nitrous oxide.

The complications encountered by the responders in their clinical practice were desaturation, postopera­tive nausea vomiting, delivery of accidental hypoxic mix­ture due to lack of respiratory gas monitor, brain bulging and pneumocephalus.

Two hundred and thirty eight (66.11%) responders believed that operating theatre pollution by nitrous oxide was a problem, despite the increased use of circle sys­tems. The remainder (33.89%) felt that there was no pollution in the operating theatre environment.

Two hundred and twenty four (62.22%) respond­ers did not feel that their use of nitrous oxide had been influenced by the effect of pollution on staff or their health implications (question 7). Suggestions as to what mea­sures could be taken to reduce the pollution in operating theatre for staff (question 15) included encouraging greater use of TIVA, increasing use of low flow anaes­thesia and circle systems, better ventilation in the oper­ating theatres, need for greater education and training in measures to reduce pollution, reducing the use of nitrous oxide and using an alternative gas, such as xenon.

Two hundred and sixty four responders (73.33%) used halothane with nitrous oxide while72.22% respond­ers used it with isoflurane. The users of sevoflurane with nitrous oxide were only 34.44%. Most commonly used opioid with nitrous oxide was fentanyl(70.56%), followed by pentazocine (53.89%), pethidine(37.22%), morphine (35%) and sufentanil (20%).

   Medical air Top

The responses to question-10 showed that 186 (51.67%) responders did not have medical air in the op­erating theatres while 174 (48.33%) had the provision of medical air. When asked whether medical air was used when it was available (question-11), 240 (66.67%) stated in the affirmative, while 120 (33.33%) were unwilling to use it.

   Tiva Top

In response to question-12, 344 (95.56%) of anaesthesiologists stated that they used TIVA, with 132 (36.67%) using frequently and 214 (59.44%) using occa­sionally. When TIVA is used (question-13), 214 (59.44%) supplement anaesthesia with oxygen/nitrous oxide and 156 (43.33%) supplement with oxygen and air.

Further analysis was carried out on the 80 (22.23%) female responders to determine whether there was any greater concern regarding health and pollution issues. Questions-2 and 7 were combined to determine whether, over the last 5 years, nitrous oxide use had decreased and whether this was influenced by the effect of pollution on staff or other health considerations. Ten (12.5% of fe­males) stated that probability of health hazards had led to the decrease in the use of nitrous oxide. Further analysis was also carried out on questions-6 and 7 to determine whether the responders felt that pollution was still a prob­lem in operating theatre areas that had influenced their own practice. 44(55%) felt that it had, with 26(32.5%) stating that they did think that pollution was a problem but had not changed their practice as a result of it.

   Discussion Top

Modern anaesthetic practice incorporates nitrous oxide primarily to facilitate reduction in dose of other anaesthetic agents and opioids thereby minimizing un­wanted adverse effects of these agents and reducing overall cost of anaesthesia. It is also used to provide quicker induction of anaesthesia and recovery from the same, especially when newer inhalational agents are not available.

The results show that nitrous oxide is a valuable part of current clinical anaesthetic practice. However, 27.22 % of total anaesthesiologists, of which 53.13% were neuro- anaesthesiologists, reported that their use of the gas over the past 5 years had decreased. Reduc­tion in the use of nitrousoxide is mainly because of medi­cal indications, frequent use of TIVA and also perhaps the increasing availability of medical air. The response is not suggestive of a conscious avoidance related to health hazards or pollution issues.

In the survey, majority of the anaesthesiologists felt that nitrous oxide pollution in operating theatres was a problem, despite the use of circle systems. 39.44% have decreased their use of nitrous oxide because of the health considerations and effect of occupational hazards to the staffs. Strangely enough 96.66 % did not alter their prac­tice in using the gas though they considered nitrous ox­ide to be a polluting agent with potential adverse effect on health. One contributing factor may be lack of provi­sion of medical air on the anaesthetic machine, and thus being obliged to use nitrous oxide as a carrier gas.

Most attention regarding occupational and environ­mental hazards brought about by the anaesthetic agent in operating theatres has been focused on studies in the 1970s [9] into the outcome among theatre workers. In 1992, Rowland et al showed a significant risk of reduced fertil­ity in female dental assistants exposed to unscavenged nitrous oxide for five hours or more a week [10] . Several epidemiological studies have linked occupational expo­sure to nitrous oxide with spontaneous abortions, de­creased rates of fertility and congenital foetal anomalies [11][12][13][14][15][16][17] . From the data, it cannot be deduced whether fur­ther awareness and knowledge is required regarding occupational and environmental hazards brought about by the anaesthetic agent in operating theatres but many respondents felt that there is a clear need for occupa­tional hygiene monitoring to ensure that occupational exposure standards are not being exceeded. Some of the suggested measures to reduce theatre pollution as per respondents included installing a ventilation system and scavenging equipment, regular inspections for leaks and defective equipment, and good anaesthetic technique. This should be further supported by a commitment to training so that all concerned understand the preventive measures required.

In a developing country like India, where socio­economic condition is poor, the provision of scavenging system and medical air is not so frequent, and thus we have not questioned whether a restriction should be placed on the use of nitrous oxide. It may be contemplated whether this survey will have any impact on such a sce­nario where the probability of having only TIVA exists as an alternative to nitrous oxide.

Our database has a response biased towards the male population. Consideration must be given to the fact that the health effects associated with nitrous oxide may be of greater concern to females and thus male anaesthesiologists may not perceive the problem related to the continuous use of nitrous oxide. For this reason the response of the female anaesthetists were analyzed in isolation. However, the results do not show any greater concern about pollution issues among female anaesthesiologists.

This survey has obtained the views of the consult­ant body, which is a substantially male population. In or­der to assess the attitudes of younger anaesthesiologists and incidentally access a population with a larger pro­portion of females, it is intended to repeat the survey in trainee anaesthesiologists.


A Questionnaire Survey on the use of Nitrous Oxide in current anaesthetic practice.

Name Sex: Male/Female

Speciality: General/ Neuro/ Cardiac/ Others (Specify) Institute: Government/ Private Institute: Years in clinical anaesthesia practice:

Phone/ Email:

1. How often do you use Nitrous oxide?

a) Frequently b) Occasionally c) Never

2. The use of Nitrous oxide in past 5 years has:

a) Increased b) Decreased c) Stayed the same

3. Do you avoid using Nitrous oxide for any particular operation?

a) Yes b) No


4. Do you use Nitrous oxide in closed circuit with circle absorber?

a) Always b) Sometimes c) Never

5. Any complications encountered with the use of Nitrous oxide? Comments:

6. Do you think that Nitrous oxide causing operating theatre pol­lution is a problem?

a) Yes b) No

7. Has your use of NO been influenced by the effect of pollution on staff or other health considerations?

a) Yes b) No

8. Tick the inhalational anaesthetics you use:

a) Halothane b) Isoflurane c) Sevoflurane d) Ether

9. Analgesics / Opiods commonly used by you:

a) Morphine b) Pethidine c) Fentanyl d) Sufentanil e) Pentazocine f) Others

10. Does your machine has medical air?

a) Yes b) No

11. Do you use medical air when it is available?

a) Yes b) No

12. Do you practice total intravenous anaesthesia (TIVA)?

a) Frequently b) Occasionally c) Never

13. If you use TIVA, what do you supplement anaesthesia with?

a) Oxygen/Air b) Oxygen/Nitrous oxide

14. Scavenging system?

a) Yes b) No c) Not available

15. What measures do you think could be taken to reduce the theatre pollution?


   References Top

1.Gray WM. Occupational exposure to nitrous oxide in four hospitals. Anaesthesia 1989; 44: 511-4.  Back to cited text no. 1  [PUBMED]    
2.Hall JE, Henderson KA, Oldham TA, Pugh A, Harmer M. Environmental monitoring during gaseous induction with sevoflurane. Br J Anaesth 1997; 79: 342-5.  Back to cited text no. 2      
3.Henry RJ, Jerrell KG. Ambient nitrous oxide levels during pe­diatric sedations. Pediatr Dent 1990; 12: 87-91.  Back to cited text no. 3      
4.Hoerauf RJ, Koller C, Taeger K, Hobbhahn J. Occupational exposure to sevoflurane and nitrous oxide in operating room personnel. Int Arch Occup Environ Health 1997; 69: 134-8.  Back to cited text no. 4      
5.Suruda AJ, McGlothlin JD. Fatal abuse of nitrous oxide in the workplace. J Occup Med 1990; 32: 682-4.  Back to cited text no. 5  [PUBMED]    
6.Rosenberg H, Orkin FK, Springstead J. Abuse of nitrous ox­ide. Anesth Analg 1979; 58: 104-6.  Back to cited text no. 6  [PUBMED]  [FULLTEXT]  
7.Blanco G, Peters HA. Myeloneuropathy and macrocytosis asso­ciated with nitrous oxide abuse. Arch Neurol 1983; 40: 416-28.  Back to cited text no. 7  [PUBMED]  [FULLTEXT]  
8.Henderson KA, Mathews IP. An environmental survey of com­pliance withoccupational exposure standards (OES) for anaes­thetic gases. Anaesthesia 1999; 54: 941-7.  Back to cited text no. 8      
9.Layzer RB. Myeloneuropathy after prolonged exposure to nitrous oxide. Lancet 1978; 2: 1227-30.  Back to cited text no. 9  [PUBMED]    
10.Rowland AS, Baird DD, Weinberg CR, Shore DL, Shy CM, Wilcox JA. Reduced fertility in women employed as dental assistants exposed to high levels of nitrous oxide. New Engl J of Med 1992; 327: 993-7.  Back to cited text no. 10      
11.Baird PA. Occupationalexposure to nitrous oxide - not alaugh­ing matter. New Engl J Med 1992; 327: 1026-7.   Back to cited text no. 11  [PUBMED]    
12.Cohen EN, Gift HC, Brown BW. Occupational disease in den­tistry and chronic exposure to trace anaesthetic gases. Journal of American Dental Association 1980; 101: 21-31.  Back to cited text no. 12      
13.Hemminki K, Kyyronen P, Lindbohm ML. Spontaneous abor­tions and malformations in the offspring of nurses exposed to anaesthetic gases, cytotoxic drugs and other potential hazards in hospital based on registered information of outcome. J Epidemiol Community Health 1985; 39: 141-7.  Back to cited text no. 13      
14.Rosenberg P, Kirves A. Miscarriages among operating theatre staff. Acta Anaesthesiologica Scandinavica 1972; 53: 37-42.  Back to cited text no. 14      
15.Tomlin PJ. Health problems of anaesthetists and their families in the west midlands. Br Med J 1979; 1: 779-84.  Back to cited text no. 15  [PUBMED]  [FULLTEXT]  
16.Knill-Jones RP, Rodrigues LV, Moir DD, Spence AA. Anaes­thetic practice and pregnancy. Controlled survey of women anaesthetists in the United Kingdom. Lancet 1972; 1: 1326-8.  Back to cited text no. 16  [PUBMED]    
17.Henderson KA, Raj N, Hall JE. The use of nitrous oxide in anaesthetic practice: a questionnaire survey. Anaesthesia 2002; 57: 1155-8.  Back to cited text no. 17  [PUBMED]    


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