Users Online: 1441 Home Print this page Email this page Small font sizeDefault font sizeIncrease font size  
Home | About us | Editorial board | Search | Ahead of print | Current issue | Archives | Submit article | Instructions | Subscribe | Contacts | Login 

RSACP wishes to inform that it shall be discontinuing the dispatch of print copy of JOACP to it's Life members. The print copy of JOACP will be posted only to those life members who send us a written confirmation for continuation of print copy.
Kindly email your affirmation for print copies to [email protected] preferably by 30th June 2019.


Table of Contents
Year : 2016  |  Volume : 32  |  Issue : 2  |  Page : 277-278

Vaporizer interlock malfunctioning

Department of Anaesthesiology, Critical Care and Pain, Tata Memorial Hospital, Mumbai, Maharashtra, India

Date of Web Publication10-May-2016

Correspondence Address:
Jeson R Doctor
501-Divyalok, L D Ruparel Marg, Malabar Hill, Mumbai, Maharashtra - 400 006
Login to access the Email id

Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0970-9185.173389

Rights and Permissions

How to cite this article:
Doctor JR, Solanki SL. Vaporizer interlock malfunctioning . J Anaesthesiol Clin Pharmacol 2016;32:277-8

How to cite this URL:
Doctor JR, Solanki SL. Vaporizer interlock malfunctioning . J Anaesthesiol Clin Pharmacol [serial online] 2016 [cited 2021 May 7];32:277-8. Available from:


A 50 years old female was posted for modified radical mastectomy under general anesthesia. The anesthesia workstation in use was Drager Fabius with Drager 2000 sevoflurane and isoflurane vaporizers attached to the Selectatec back bar mounting of the machine. During the course of the anesthesia, we noticed that the vaporizer interlock, which allows switching on of one vaporizer at a time was malfunctioning and allowed the switching on of second vaporizers simultaneously [Figure 1]. Normally, the interlock mechanism on top of the vaporizer has a pin in the slot that fits the interlock bar in a closed position only [Figure 2]a. The interlock closes only with the vaporizer in the off position and not when it is in use with a maximum dial concentration.
Figure 1: Two vaporizers in use simultaneously

Click here to view
Figure 2: (a) Intact interlock pin and (b) A broken interlock pin

Click here to view

In our case, the vaporizer interlock malfunctioned allowing the use of the second vaporizer while one vaporizer was already in use. Buettner [1] reported as case of vaporizer malfunction and subsequent switching on the second vaporizer. In that case, error was in the distance between the center line and the locking pin, which was 1.63 mm shorter than the manufacturer specifications. Kim and Kim [2] described a case in which there was interruption in the supply of breathing gas during anesthesia caused by malposition of the Drager Vapor 2000 vaporizer, which was accidentally tilted and lifted off the Selectatec manifold of the anesthesia machine. Cooper et al. [3] mentioned that human error was involved in 82% while, equipment failure in 14% of preventable incidents. In our case, we found that the pin inside this slot was broken [Figure 2]b] and the interlock could be shut with the dial concentration in the maximum position, thereby allowing the second vaporizer to be switched on simultaneously. This would be significant if by an error or oversight two vaporizers would be on causing harm to the anaesthetized patient. In this case it is purely a human error of not finding the broken pin of vaporizer while doing preuse check, but it may go unnoticed because the pin is slightly deep inside the slot for the interlocking bar. Purpose of reporting this case is to highlight the preuse checking of vaporizer for any broken pin inside the slot for interlocking bar besides checking for another safety test. This vaporizer interlock safety mechanism is not a part of routine safety check but needs incorporation in the revised safety checklist with the advent of newer technology.

  References Top

Buettner AU. Failure of vaporizer interlock mechanism. Anaesth Intensive Care 2000;28:451-2.  Back to cited text no. 1
Kim HJ, Kim MW. Interruption in the supply of breathing gas during general anesthesia due to malposition of the vaporizer - A case report. Korean J Anesthesiol 2010;59:270-4.  Back to cited text no. 2
Cooper JB, Newbower RS, Long CD, McPeek B. Preventable anesthesia mishaps: A study of human factors 1978. Qual Saf Health Care 2002;11:277-82.  Back to cited text no. 3


  [Figure 1], [Figure 2]


    Similar in PUBMED
   Search Pubmed for
   Search in Google Scholar for
    Access Statistics
    Email Alert *
    Add to My List *
* Registration required (free)  

  In this article
   Article Figures

 Article Access Statistics
    PDF Downloaded273    
    Comments [Add]    

Recommend this journal