|Year : 2007 | Volume
| Issue : 5 | Page : 405
A Survey on Use of Nitrous Oxide in Current Anaesthetic Practice in India
Jayanta Kumar Mitra1, Virendra Jain1, Deepak Sharma1, Hemanshu Prabhakar2, HH Dash3
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 Acceptance||04-Aug-2007|
|Date of Web Publication||20-Mar-2010|
H H Dash
(Prof. & Head) Department of Neuroanaesthesiology, 7th floor, Neurosciences Centre, All India Institute of Medical Sciences, New Delhi -110029
Source of Support: None, Conflict of Interest: None
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 2020 Sep 27];51:405. Available from: http://www.ijaweb.org/text.asp?2007/51/5/405/61171
| Introduction|| |
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 ,,, resulting in potential occupational hazard. The problem of addiction , and development of myeloneuropathy , 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|| |
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|| |
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|| |
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|| |
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|| |
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|| |
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  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  . Several epidemiological studies have linked occupational exposure to nitrous oxide with spontaneous abortions, decreased rates of fertility and congenital foetal anomalies  . 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:
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?
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