Anesth Analg 2006;102:655-656
© 2006 International Anesthesia Research Society
doi: 10.1213/01.ANE.0000190792.60519.48
LETTER TO THE EDITOR
A Strange Place to Find a Cable Tie
Karl Wagner, MD, and
Joy Loy, MD
Department of Anesthesia, MetroHealth Medical Center, Cleveland, OH, karlwagner3{at}yahoo.com
To the Editor:
A 66-yr-old male patient with a history of cough had a lung mass on chest radiograph. The patient’s past medical history is significant for asthma, emphysema, and tuberculosis exposure. The patient was scheduled for a bronchoscopy and mediastinoscopy. After IV sedation with midazolam, anesthesia was induced with propofol, fentanyl, and rocuronium; the trachea was intubated with a number 8.0 endotracheal tube and mechanical ventilation was started. General anesthesia was maintained with isoflurane 50% oxygen and 50% air.
Our anesthesia machines are Narcomed GS machines. After anesthesia was induced, but before beginning bronchoscopy, the bellows would fall during the expiratory phase. The circuit, machine, and ventilator were fully checked preoperatively and found to be in working order. The circuit was rechecked and was found to be without leak. We were able to ventilate the patient’s lungs easily with the hand bag. All hoses and parts of the machine, circuit, and ventilator were tight and intact. However, the ventilator had a 6LPM leak. Our anesthesia technician and maintenance engineer (who is Narcomed certified) were called. They examined the ventilator and found a plastic tie to have wedged itself between the ball valve and the bar in the ventilator’s relief valve.
The machines are checked for functioning every day before cases by the anesthesia personnel. The machines get a maintenance check by our maintenance engineer once per quarter. The distributor sends a Narcomed trained technician to examine the machines and change the bellows once per year. The distributor serviced the machine in question in February and this problem occurred in August. Our equipment manager called Narcomed to tell them of the incident; they replied that this is the first time they have heard of this occurring. Because this is the only occurrence of which they are aware, they will only advise vigilance and care when working on the machines. They do not feel that it is necessary for a design change or any other action at this time. They were, however; thankful for the report.
We hypothesize that the tie fell into the scavenging pipe during a maintenance visit from the distributor in February. That is the only time that this part of the machine would have been opened in the fashion necessary for a cable tie to slip into that space. It was just a matter of time and random chance that the flow of gas would push the tie into the valve. In our case it took 6 months. We do not have any other record of the machine in question being serviced in this fashion between February and August. There are two cable ties that lie just superior to the ventilator’s relief valve that are used to secure a piece of tubing (Fig. 1). The source of the ectopic tie is unknown but it could easily have been an extra tie that slipped from the hand of the distributor during the maintenance check or one that had fallen in the scavenging pipe during the original placement of the system (Fig. 2).
Although taking the bellows apart during a case is not the best time to work on maintenance, it is sometimes necessary. This is not a common occurrence but can be part of the differential of ventilator failure during a case. In our department, including personnel in anesthesia for 30 years, no one had seen this occur before.
