To the Editor:—
Routine inspection and examination of anesthesia equipment before use may fail to detect certain manufacturing defects. We describe a case of an endotracheal pilot balloon that failed to inflate as a result of a defective 12-ml Luer Lock Tip syringe.
A 35-yr-old man was scheduled for a right inguinal hernia repair under general anesthesia. After induction and intubation using a prechecked 7.0-mm internal diameter, high volume, low pressure cuff, endotracheal tube (Rusch Inc., Duluth, GA), attempts to inflate the endotracheal cuff through the pilot balloon using a 12-milliliter Luer Lock Tip syringe (MONOJECT, Sherwood Davis & Geck, ST. Louis, MO) were unsuccessful. Air could not be injected from the syringe into the pilot balloon even under extreme force. With a probable diagnosis of the pilot valve being stuck in the closed position and the presence of a large air leak around the uninflated cuff, the endotracheal tube was replaced with an identical endotracheal tube that was successfully inflated using a different 12-ml syringe. The remaining course of anesthesia was uneventful. Inspection of the initial endotracheal tube and the original 12-ml Luer Lock Tip syringe revealed a defective tip on the syringe as the cause of this incident (fig. 1).
Tyco Healthcare, owner of Sherwood Davis & Geck, St. Louis, Missouri, was invited to provide comments regarding this letter. No comments were submitted.—Michael M. Todd, Editor-in-Chief
The pilot balloon valve is a spring-loaded bidirectional valve that is by default in the closed position. When the tip of the Luer Lock Tip syringe presses the shaft of the spring-loaded valve inward, it depresses the internal ring, thus opening the valve and allowing inflation and deflation of the cuff (fig. 2, top). Any defect in the syringe tip preventing the depression of the shaft will result in failure of air passage. In our case, the defect was a decrease in the thickness of the syringe tip wall, resulting in an increase in internal diameter of the tip. An increase in the internal diameter allows the syringe tip to encircle the shaft of the valve and preventing its proper engagement and depression. Without the ability to depress the shaft and hence the internal ring, the valve is kept in the closed position preventing the passage of air. (fig. 2, bottom).
Because a different syringe was used to test the endotracheal tube, the malfunction was not observed during the preoperative period. It was not until after intubation when the defective syringe was used that the cuff failed to inflate. The defect in the syringe was not immediately identified, as a 1-mm discrepancy in luminal wall thickness of the syringe tip was not readily apparent. Using the same syringe perioperatively could have prevented this incident, thus preventing unnecessary extubation and reintubation of the trachea.
* John H. Stroger, Jr. Hospital of Cook County and Rush Medical College, Chicago, Illinois. firstname.lastname@example.org