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Year : 2018  |  Volume : 12  |  Issue : 4  |  Page : 907-913  

Practice pattern of fresh gas flow and volatile agent choices among anesthesiologists working in different Indian hospitals: An online survey

Department of Anaesthesiology and Critical Care, All India Institute of Medical Sciences, Raipur, Chhattisgarh, India

Date of Web Publication18-Dec-2018

Correspondence Address:
Dr. Habib Md Reazaul Karim
Department of Anaesthesiology and Critical Care, All India Institute of Medical Sciences, Raipur, Chhattisgarh
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/aer.AER_164_18

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Background: Fresh gas flow (FGF) during volatile inhalational agent-based anesthesia is a concern for many reasons. Advancement in anesthesia workstation (WS) and monitoring of anesthesia gas concentrations has led to the feasibility of lower flow safely. However, the practice pattern is not yet well known. The information can help us in better protocol formation. Aim: The survey was aimed to know the prevailing practice pattern of FGF and volatile agent choices and compare them among anesthesiologists of different working setups and experiences. Materials and Methods: With approval, the present cross-sectional survey was conducted using SurveyMonkey® software from January 2018 to May 2018. Anesthesiologists working in different organizations across India were approached through E-mail and WhatsApp. Anonymous responses were collected, expressed in number and percentage scale, as well as compared using INSTAT software and appropriate tests; P < 0.05 was considered statistically significant. Results: A total of 251 (15.2%) responses were received and 249 were analyzed. Overall, 87% of respondents were using anesthesia WS and 71% were using nitrous oxide as balance gas. The FGF of <600 mL/min was highest with desflurane. Minimum alveolar concentration (MAC) monitoring was very poor in nonteaching (NT) hospitals as compared to teaching hospitals; P < 0.0001. The Boyle's machine was more common in use in NT hospitals as compared to medical colleges and corporate hospitals; P < 0.0001. Conclusion: Low-flow anesthesia (LFA) use is still suboptimal, and there are ample opportunities to increase and optimize the FGF used. The use of Boyle's machine is associated with higher flow use. MAC monitoring and LFA use are poor in NTs.

Keywords: Anesthesia machine, desflurane, isoflurane, low-flow anesthesia, sevoflurane

How to cite this article:
Kumar M, Sinha M, Reazaul Karim HM, Panda CK, Singha SK. Practice pattern of fresh gas flow and volatile agent choices among anesthesiologists working in different Indian hospitals: An online survey. Anesth Essays Res 2018;12:907-13

How to cite this URL:
Kumar M, Sinha M, Reazaul Karim HM, Panda CK, Singha SK. Practice pattern of fresh gas flow and volatile agent choices among anesthesiologists working in different Indian hospitals: An online survey. Anesth Essays Res [serial online] 2018 [cited 2019 Jun 25];12:907-13. Available from:

   Introduction Top

Inhaled anesthetics are recognized as greenhouse gases.[1] On the basis of the derived 100-year global warming potential, the average climate impact per anesthetic procedure at the University of Michigan was the same as the emission of ~22 kgCO2.[2] Low-flow anesthesia (LFA) reduces the amount of anesthetic agents used, and thus reduces the operation theater (OT) pollution, the greenhouse effect, and the damage of the Ozone layer by reducing production of fluorocarbons. Furthermore, reduced anesthetic gas consumption makes it more economical.[3] It also benefits in terms of heat and humidity preservation by recirculating the rebreathing gases. LFA also reduces the nitrous oxide (N2O) pollution if used.[4] LFA has been reported as a good choice to achieve enhanced recovery after surgery as well.[5]

With the advancement of anesthesia workstation (WS) and monitoring of anesthesia gas concentrations, LFA can be safely used. The scavenging system and high fresh air ventilation system remove waste anesthetic gases (WAGs) from the OT, but environmental pollution remains the same. However, the acceptance and practice pattern of LFA among anesthesiologists working in different working setups are not well evaluated. The information on this aspect can help us in policymaking and implementation. The present survey was carried out with an objective to know the prevailing practice pattern of fresh gas flow (FGF) and volatile agent choices and compare them among anesthesiologists of different working setups of Indian hospitals.

   Materials and Methods Top

The present survey was conducted after getting approval from the affiliated institute with an exemption for consent. The clinical trial registration was not required as per the rule of Clinical Trial Registry-India. The present cross-sectional survey was conducted from January 2018 to May 2018 and was created and conducted using online survey software and a questionnaire tool service from SurveyMonkey® (SurveyMonkey Inc., USA, A link to the online survey was sent to anesthesiologists, using E-mails and WhatsApp (, California, USA), a social media platform, working in different organizations across the country (India). Reminder E-mails were also sent to potential responders if no reply was received after 2 weeks of the original E-mail request. Responses were collected anonymously via the survey. The online survey was conducted using a questionnaire tool which consisted of ten questions [Annexure]. The questionnaire was validated internally from three experts and externally by two experts in the field before starting the survey and was supplied in English-only version. The questionnaire was designed to get data with regard to affiliation, workplace, FGF used, preferred volatile anesthetic agents used, minimum alveolar concentration (MAC) monitoring, etc., The agent-specific FGF use was also sought from multiple predefined categories.

Data processing and statistical management

The responses were directly downloaded and entered in Excel file master chart and basic tables. Categorical variables were described as number (percentages). The primary objective of the present survey was to find out the practice pattern for FGF used by different anesthesiologists working in different setups. The government medical college (GMC) was taken as standard, and the practice of anesthesiologists working in other setups was compared using Fisher's exact test. P ≤ 0.05 was considered statistically significant. The INSTAT software version 1 (GraphPad Prism Software Inc., La Jolla, CA, USA) was used for this purpose.

   Results Top

A total of 1050 E-mails and link to six WhatsApp groups having a total of 600 members were sent. A total of three reminders were also sent to the potential responders. A total of 251 (15.2%) anesthesiologists responded to the questionnaire; two responses were grossly incomplete and excluded from data analysis. One hundred and nine (43.8%) respondents were working in GMCs/institutes and 54 (21.7%) were from corporate and private hospitals-teaching (CH-T). Eighty-six (34.5%) were from nonteaching (NT) hospitals. The workplace-wise distributions are presented in [Table 1].
Table 1: Workplace-based distribution and comparison of responses tested using Fisher's exact test

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The majority (87%) of the respondents were using anesthesia WS and 71% were using N2O as balance gas. The use of FGF of <600 mL/min was very low, yet highest with desflurane 17.43% as compared to isoflurane and sevoflurane (12.84% vs. 10.09%). The use of FGF of 600–1000 mL/min was, however, similar for all modern volatile agents. MAC monitoring was very poor in private NT hospitals as compared to GMCs (34% vs. 75%; P > 0.0001). While MAC monitoring was equally done in CH (74%), fair in government NT hospitals (63%), it was poor in private NT hospitals as compared to government sector medical colleges/institutes [Table 1]. Overall, 13.25% of respondents were still using Boyle's machine. Of them, 60.6% were working in private NT hospitals, while all the respondents working with CH-T were working with anesthesia WS.

While there was no difference in the anesthesia machine and balanced gas used, the use of sevoflurane as the preferred volatile anesthetic agent was highest among anesthesiologists with 10–20 years of experience as compared to newcomer, i.e., <5 years of experience (50% vs. 22.22%; P 0.001) [Table 2]. There was no difference in the use of FGF for different agents among the anesthesiologists with different levels of experience [Table 2].
Table 2: Experience-based distribution and comparison of responses tested using Fisher's exact test

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The Boyle's machine was more common in use in the private NT hospitals as compared to the GMC and CH-teaching hospitals (60.61% vs. 18.18% and 0%, respectively; P < 0.0001). While isoflurane was the commonest (55%) volatile anesthetic agent used, halothane was the most commonly used inhalational agent (51.5%) among the anesthesiologists using Boyle's machine [Table 3].
Table 3: Anesthesia machine-based distribution and comparison of responses tested using Fisher's exact test

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As compared to the WS, higher FGF pattern was seen with Boyle's machine irrespective of the inhalational agent being used (e.g., >2000 mL/min with isoflurane 14.36% vs. 36.37; 13.89% vs. 27.27% with sevoflurane, and 10.65% vs. 24.24% with desflurane).

   Discussion Top

With the introduction of modern volatile anesthetic agents and anesthesia gas monitoring, the use of low FGF has become feasible and has reported being widely accepted even in developing countries like India.[6] LFA allows rebreathing of vehicle gases. By decreasing the FGF and increasing the recirculating gases, inhalational agents get reused as they have a poor uptake and also poorly metabolized.[7],[8] This would lower the economic costs and would contribute to a greener earth. A low FGF is also mandatory to ensure the satisfactory gas exchange and better dynamics of volatile agents due to multiple reasons.[9]

While a previous survey has shown that 73% of the responders were using LFA routinely,[6] it is not much known about the flow used with context to different anesthetic agents. The present survey was conducted to know the choice of inhalational agents and practice pattern of FGF with different inhalational agents among the anesthesiologists working across the different hospital setups of India.

Choice of volatile anesthesia and fresh gas flow

Anesthesiologists have remained discontented about the cost of volatile anesthetics such as sevoflurane and desflurane. The majority of the anesthesiologists were using isoflurane, probably because of the relatively lower cost and availability in the hospital. Halothane is also less costly, yet it was found to be used less commonly than isoflurane as a preferred agent, probably because of safety concerns. However, the present survey points out a few interesting facts like sevoflurane being more costly than isoflurane had been more frequent in use (46.3%) in CH-T and the CH-T was using an FGF 600–1000 mL/min (44.4%) even for sevoflurane. The use of FGF >2000 mL/min even with sevoflurane was rare in the CH-T. The use of desflurane was also very high in CH-T. The only other setup which used desflurane was GMCs. However, desflurane was the preferred agent only in 5% of anesthesiologists. Though the cost of desflurane is relatively higher, the use of FGF <600 mL/min is often used with desflurane. It has been shown that the consumption of desflurane reduces drastically with the low FGF and the time duration of anesthesia.[10] There was no difference in the type of anesthetic machine used in GMC and CH-T. The present survey also showed that sevoflurane was used by more senior peoples than the newcomers. This finding may be because of that the senior people (in the present survey) were working more in GMC and CH-T, where it is more available along with WSs. A cost–benefit analysis should also include any clinical advantages and disadvantages incurred in the context. Although sevoflurane and desflurane are relatively costlier, their use has been associated with good numbers of advantages. A simple educational reminder of ways to reduce sevoflurane use was evaluated and found that the cost incurred by sevoflurane was drastically reduced despite having the same workload.[11]

Monitoring of minimum alveolar concentration

In the present survey, a different level of experience failed to show a significant difference in the use of MAC monitoring. Anesthesiologists of the private NT hospitals were the practitioners, who were still using halothane with Boyle's machine and without MAC monitoring. The present survey also found that the MAC monitoring availability has increased as compared to the previous 2016 survey (63.9% vs. 43.9%). However, it is still not done/unavailable in nearly 25% of teaching hospitals attached with the GMC and CHs despite being recommended as a standard of care.[12] Moreover, simply having the facility/monitor displaying MAC does not necessarily indicate that MAC was monitored. Even, simply monitoring MAC does not necessarily mean that the correct MAC (i.e., MACage) was monitored,[13] and for this, more specific question and survey will be required, which was a limiting factor of our questionnaire.

Anesthetic machine and fresh gas flow

The use of basic anesthetic machine (Boyle's) was associated with higher FGF, even FGF of >2000 mL/min was extremely high as compared to the GMC (P < 0.0001). This indicates that it not only contributes to the greenhouse effect and more occupational exposure, but also it, in fact, is putting an economic burden on the public sector in the long run. Despite the growing concerns of N2O as a greenhouse gas, still, 71% of the respondents answered that they were using it as a balanced gas. Whereas 77% of anesthesiologists working in the GMC were using N2O, and only 42.5% of those working in CH-T used N2O as a carrier gas, which was a significant difference. Oxygen–air mixture was used more frequently in CHs (51.8% versus 21.1% in GMC), which is statistically significant. Medical grade air may not be available in all hospitals, and this may explain this difference. Furthermore, anesthesiologists are probably happier with N2O due to its analgesic property, rapid onset and washout, and requirement of a lesser amount of modern inhalational agents for achieving the same MAC.

A survey conducted in Iran assessing the risk management status of WAG in academicals hospitals found the status to be weak.[14] Another survey by the National Institute for Occupational Safety and Health evaluating the practices of controlling exposure to N2O found that only 13% of respondents lacked standard procedures.[15] Interestingly, only 3% were not trained in safe handling.[15] This clearly indicates that the one-time training or education may not be enough to change the practice. We may need to adopt a simple educational reminder time to time, and this method has been shown to be effective.[11] Closed-loop and low-flow technology can be used as one of the strategies to reduce WAG exposure too.[16]

The use of FGF <1000 mL/min by only 45%–48%, as found in the present survey, indicates that the use of LFA is still very poor. Compared to a previous study, the use of LFA has not even seen an increased acceptance.[6] Education may play an important role in increasing acceptance. One study evaluating the effect of LFA education on knowledge, attitude, and behavior of the anesthesia team toward the use of lower FGF showed significant impact over 3 months.[17]

The survey gives us a take-home message that it is high time to formulate education and training programs and practice policies on LFA nationwide so that the acceptance and practice of LFA increase further and benefit can be extended to the patient, health-care provider, as well as our environment. Problem-based educational program or workshops on LFA can be prepared and implemented for NT hospitals and their effectiveness in increasing the LFA can be assessed in the future.


The present survey, however, is limited by the fact that it has a relatively small sample (respondents) and was conducted in one country. However, considering the very significant findings and a high percentage of low FGF users, the conclusion drawn is unlikely to be different, even if a larger sample is taken for such a survey.

   Conclusion Top

The use of lower FGF, especially FGF <600 mL/min, is very poor. The conventional flow anesthesia practice is still prevalent despite having strong evidence of safe and effective LFA use. Interestingly, use of FGF <600 mL/min is being noted, even with sevoflurane anesthesia in CH-T. MAC monitoring and LFA use are poor in NT hospitals, and problem-based educational program or workshops on the LFA can be prepared and implemented.


We would like to thank all the respondents who spared their valuable time to take this survey.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

   Annexure - Questionnaire for Low Flow Anesthesia Survey Top

  1. Are you a

  2. Postgraduate trainee / Practicing Anaesthesiologist

    If practicing, since how long?

    < 5 Year / 5- 10 Years/ 10- 20 years / > 20 years

  3. You are working at:

  4. Government Med College or Institute,

    Govt Hospital – non-teaching,

    Corporate Hospital - teaching

    Private Hospital – non-teaching

  5. What inhalational agent you are using predominantly?

  6. Isoflurane / Sevoflurane / Desflurane / Halothane

  7. Which anesthesia machine you are using?

  8. Anesthesia workstation / Boyle's machine

  9. Which gas mixture you are using as balance/vehicle gas?

  10. O2 + N2O / O2 + Air / O2 Only

  11. What are the inhalational anesthetic agents you are using in your set-up? (can tick more than one option)

  12. Desflurane / Sevoflurane / Isoflurane / Halothane

  13. How much total fresh gas flow you are using with Isoflurane during maintenance?

  14. ≤ 600 mL min-1 / 600 – 1000 mL min-1/ 1000 – 2000 mL min-1/ > 2000 mL min-1

  15. How much total fresh gas flow you are using with Sevoflurane during maintenance?

  16. ≤ 600 mL min-1 / 600 – 1000 mL min-1/ 1000 – 2000 mL min-1/ > 2000 mL min-1

  17. How much total fresh gas flow you are using with Desflurane during maintenance?

  18. ≤ 600 mL min-1 / 600 – 1000 mL min-1/ 1000 – 2000 mL min-1/ > 2000 mL min-1

  19. Are you using MAC monitoring routinely for inhalational agents?

  20. Yes / No

   References Top

Oyaro N, Sellevåg SR, Nielsen CJ. Atmospheric chemistry of hydrofluoroethers: Reaction of a series of hydrofluoroethers with OH radicals and cl atoms, atmospheric lifetimes, and global warming potentials. J Phys Chem A 2005;109:337-46.  Back to cited text no. 1
Sulbaek Andersen MP, Sander SP, Nielsen OJ, Wagner DS, Sanford TJ Jr. Wallington TJ, et al. Inhalation anaesthetics and climate change. Br J Anaesth 2010;105:760-6.  Back to cited text no. 2
Odin I, Feiss P. Low flow and economics of inhalational anaesthesia. Best Pract Res Clin Anaesthesiol 2005;19:399-413.  Back to cited text no. 3
Karim HM, Keshwani M. Nitrous oxide in waste anesthetic gases with different fresh gas flow: A case-based pilot observation and a practical thought on scavenging. Med Gas Res 2018;8:125-7.  Back to cited text no. 4
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Senapathi TG, Suarjaya IP, Pradhana AP, Makmur E. Low flow anesthesia will gain eras (enhanced recovery after surgery). Bali J Anesthesiol 2017;1:51-4.  Back to cited text no. 5
Amma RO, Ravindran S, Koshy RC, Jagathnath Krishna KM. A survey on the use of low flow anaesthesia and the choice of inhalational anaesthetic agents among anaesthesiologists of India. Indian J Anaesth 2016;60:751-6.  Back to cited text no. 6
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Khan KS, Hayes I, Buggy DJ. Pharmacology of anesthetics II: Inhalation anesthetic agents. Contin Educ Anaesth Crit Care Pain 2014;14:106-11.  Back to cited text no. 7
Lavelle ED, Kurra S. Pharmacology of inhaled anesthetics. In: Farag E, Argalious M, Tetzlaff J, Sharma D, editors. Basic Sciences in Anesthesia. 1st ed. Cham: Springer; 2018. p. 177-93.  Back to cited text no. 8
Hönemann C, Hagemann O, Doll D. Inhalational anaesthesia with low fresh gas flow. Indian J Anaesth 2013;57:345-50.  Back to cited text no. 9
Karim HM, Yunus M, Sailo L, Sangma SJ, Syiemiong N. Pharmacoeconomics of desflurane based minimal flow anesthesia for different durations of surgery. Int J Basic Clin Pharmacol 2016;5:2528-33.  Back to cited text no. 10
Lethbridge M, Bouckley A, Chambers NA. Patterns of sevoflurane use in a children's hospital: The effects of a simple educational intervention. Anaesth Intensive Care 2007;35:550-7.  Back to cited text no. 11
Checketts MR, Alladi R, Ferguson K, Gemmell L, Handy JM, Klein AA, et al. Recommendations for standards of monitoring during anaesthesia and recovery 2015: Association of Anaesthetists of Great Britain and Ireland. Anaesthesia 2016;71:85-93.  Back to cited text no. 12
Karim HM, Narayan A, Yunus M, Kumar S, Prakash A, Sahoo SK, et al. An observational study on patient admission in the anaesthesia gas monitor and minimum alveolar concentration monitoring: A deficiency with huge impact. Indian J Anaesth 2017;61:570-4.  Back to cited text no. 13
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Asefzadeh S, Raeisi A, Mousavi A. Risk management status of waste anesthetic gases using ECRI institute standards. Iran J Public Health 2012;41:85-91.  Back to cited text no. 14
Boiano JM, Steege AL, Sweeney MH. Exposure control practices for administering nitrous oxide: A survey of dentists, dental hygienists, and dental assistants. J Occup Environ Hyg 2017;14:409-16.  Back to cited text no. 15
Deng HB, Li FX, Cai YH, Xu SY. Waste anesthetic gas exposure and strategies for solution. J Anesth 2018;32:269-82.  Back to cited text no. 16
Hanci V, Yurtlu S, Ayoğlu H, Okyay RD, Erdoğan G, Abduşoğlu M, et al. Effect of low-flow anesthesia education on knowledge, attitude and behavior of the anesthesia team. Kaohsiung J Med Sci 2010;26:415-21.  Back to cited text no. 17


  [Table 1], [Table 2], [Table 3]


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