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 Table of Contents  
Year : 2022  |  Volume : 8  |  Issue : 1  |  Page : 69-71

Erroneous display of inhalational agent..!

1 Department of Anaesthesiology, Critical Care and Pain, Mahamana Pandit Madanmohan Malviya Cancer Centre and Homi Bhabha Cancer Hospital, Varanasi, Uttar Pradesh, India
2 Department of Anaesthesiology, Critical Care and Pain, Tata Memorial Hospital, Mumbai, Maharashtra, India

Date of Submission31-Aug-2021
Date of Decision06-Dec-2021
Date of Acceptance10-Jan-2022
Date of Web Publication8-Jul-2022

Correspondence Address:
Sunil Kumar Valasareddy
Department of Anaesthesiology, Critical Care and Pain, Mahamana Pandit Madanmohan Malviya Cancer Centre and Homi Bhabha Cancer Hospital (A Unit of Tata Memorial Centre - Mumbai), Sunderpur, Varanasi - 221 005, Uttar Pradesh
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/jcrsm.jcrsm_65_21

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A well-equipped anesthesia workstation is a boon for better anesthesia practice. Advancement in technical aspects such as respiratory gas analysis made perioperative care better and safer. Any kind of equipment troubleshoot can contribute to morbidity and mortality; however, the magnitude of these is not established.

Keywords: Disinfectant, halothane, infrared sensor, sterillium

How to cite this article:
Agnihotri A, Mali MC, Valasareddy SK. Erroneous display of inhalational agent..!. J Curr Res Sci Med 2022;8:69-71

How to cite this URL:
Agnihotri A, Mali MC, Valasareddy SK. Erroneous display of inhalational agent..!. J Curr Res Sci Med [serial online] 2022 [cited 2023 May 30];8:69-71. Available from: https://www.jcrsmed.org/text.asp?2022/8/1/69/347050

  Introduction Top

A well-equipped, fully functional anesthesia delivery system is always a boon and important for safe conduct of anesthesia; however, rarely, there can be equipment malfunction which may contribute to morbidity and mortality. This has led anesthesiologists to extensively use preoperative self-checking and manual check of the workstation. Despite these checks, the equipment can show troubleshoots while it is being used. Since maintaining patient safety has always been a critical element of anesthetic practice, incident reporting is one of the key factors in achieving it.[1] Cassidy et al. reported a 13.4% incidence of faulty gas monitoring, which included underestimation of volatile agent concentration, slow response of carbon dioxide (CO2) analyzer, air entrainment and broken sampling port of gas analyzer, misreading caused by exhaust tubing of gas analyzer module trapped under the wheel of anesthetic machine leading to loss of trace and low end-tidal CO2, and detection of halothane despite gas not being used.[2] Here, we report one such case of detection of volatile anesthetic agent halothane on anesthesia monitor despite never being used on workstation or anywhere in our hospital operation theater.

  Case Report Top

A 45-year-old female ASA II with ovarian carcinoma for interval debulking surgery was planned under general anesthesia. After adequate preoxygenation, standard anesthesia protocol was followed, and induction was done with intravenous fentanyl, propofol, and vecuronium for muscle relaxation according to ideal body weight doses. Maintenance was achieved with 50% nitrous oxide in mixture along with sevoflurane to attain a minimum alveolar concentration for which we used Mind Ray WATO EX-20® workstation and monitor Beneview T6®. Within few minutes of switching to the sevoflurane vaporizer, the gas monitor started displaying halothane erroneously along with sevoflurane [Figure 1] despite halothane being never used in that workstation or anywhere in our hospital. We tried to resolve the problem by switching off the Beneview T6® monitor and restarting it, assuming the anesthetic gas module will re-calibrate itself while rebooting but it was in vain. To proceed further with surgery, we changed the anesthesia workstation along with the monitor, while maintaining the depth of anesthesia under intravenous propofol. With a new workstation and monitor, inspired and end-tidal detection of sevoflurane was started and surgery progressed and completed uneventfully.{Figure 1}

  Discussion Top

In anesthesia practice, measurement of gases such as nitrous oxide, volatile anesthetic agents, and CO2 is also required along with oxygen. These could be measured by using various techniques such as infrared (IR) absorption spectroscopy, photoacoustic spectroscopy, silicone rubber and piezoelectric absorption, refractometry, Raman scattering, and mass spectrometry.[3] IR analyzers are commonly used for measuring volatile gas concentration by side-sampling method on the anesthesia workstation or the monitor installed with an anesthetic gas module (AGM).

Usually, an IR analyzer isolates a gas by dispersive or nondispersive method to detect the absorbance characteristics of the gas sample at a specific wavelength as per Beer-Lambert law; for multiple gases measurement, it passes through absorption cell via an optical IR filter which selects a specific band of IR to pass, identify, and analyze the concentration of the anesthetic agent.

Absorbance peaks for CO2and nitrous oxide are located at the 4–5 μm range, and anesthetic agents are at the 8–13 μm range. The refractive index of volatile agents such as enflurane, isoflurane, and sevoflurane overlaps (1540.4, 1563.3, and 1538.3, respectively),[4] thus requiring a complex method, along with advanced calculation techniques to identify and measure them.

In our case on follow-up with the technical support (biomedical and service engineer) team, no fault was found in IR sensors of AGM of Beneview T6® monitor. However, a few possible causes were postulated on the literature search like (a) incorrect filling of vaporizers but was ruled out as halothane was not utilized anytime in hospital, (b) wrong detection of halothane during trigger-free anesthesia in malignant hyperthermia patient,[5] (c) factitious reading of AGM resulting from incorrect identification of patient's expired methane as halothane,[6] (d) interference with hydrofluro-alkane (HFA)-based inhaler, most commonly used HFA inhalers in the operating room (OR) is salbutamol nebulizer,[7] we had not used any nebulizer for this patient or in any of our prior day cases, and (e) condensation in sample line or in water trap (appeared clear in preliminary check during the time of troubleshoot).[3]

On a retrospective investigation, we found that workstation, monitor, and facemask were thoroughly cleaned by sterillium® by our newly joined OR assistant while doing his/her regular preparation for daily schedule. Sterillium®, an alcohol-based disinfectant containing 2-propanol, 1-propanol, and ethyl-hexadecyl-dimethyl ammonium-ethyl sulfate, is commonly used as hand sanitizer, not recommended for surface cleaning of workstation, monitor, and other anesthesia equipment. Propanol, a constituent of sterillium®, an isomer of isopropyl alcohol, has an absorption range of 8–13 μm.[8] Traces of sterillium probably could have been the reason for detection of halothane. Following this incident, an institutional protocol was made by infection control team after training staff for surface cleaning before and after usage of equipment by appropriate alcohol-based reagents rather than any other alternative reagents with necessary supervisory roles as mentioned [Table 1].{Table 1}

  Conclusion Top

We conclude that wrong identification of volatile anesthetic agents by AGM may lead to unnecessary hassles in conduct of anesthesia, at the same time giving hint that the ongoing gas monitoring is not reliable to ensure adequate depth of anesthesia. Hence, a proper periodical maintenance of workstation, following appropriate cleaning techniques and creating awareness about maintanence aspects among individuals working with these equipments can overcome these hassles.

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Conflicts of interest

There are no conflicts of interest.

  References Top

Merry AF. Safety in anaesthesia: Reporting incidents and learning from them. Anaesthesia 2008;63:337-9.  Back to cited text no. 1
Cassidy CJ, Smith A, Arnot-Smith J. Critical incident reports concerning anaesthetic equipment: Analysis of the UK National Reporting and Learning System (NRLS) data from 2006-2008*. Anaesthesia 2011;66:879-88.  Back to cited text no. 2
Garg R, Gupta RC. Analysis of oxygen, anaesthesia agent and flows in anaesthesia machine. Indian J Anaesth 2013;57:481-8.  Back to cited text no. 3
[PUBMED]  [Full text]  
Wallroth CF, Gippert KL, Ryschka M, Falb W, Hattendorff HD, Schramm B, et al. Refractive indices for volatile anesthetic gases: Equipment and method for calibrating vaporizers and monitors. J Clin Monit 1995;11:168-74.  Back to cited text no. 4
Hawkes CA. Factitious halothane detection during trigger-free anesthesia in a malignant hyperthermia susceptible patient. Can J Anaesth 1999;46:567-70.  Back to cited text no. 5
Moens YP, Gootjes P. The influence of methane on the infrared measurement of anaesthetic vapour concentration. Anaesthesia 1993;48:270.  Back to cited text no. 6
Shah SB, Hariharan U, Bhargava AK. Anaesthetic in the garb of a propellant. Indian J Anaesth 2015;59:258-60.  Back to cited text no. 7
[PUBMED]  [Full text]  
Plyler EK. Infrared spectra of methanol, ethanol, and n-propanol. J Res Natl Bur Stand 1952;48:281.  Back to cited text no. 8


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