Development of a circumallergenic guayule latex endotracheal tube cuff

Authors: HERKINS, ASHLEY - The Ohio State University; DAVIS, SARAH - Energyene Inc; Cornish, Katrina

Submitted to: Biomedical Materials & Devices
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/31/2024
Publication Date: 1/28/2025
Citation: Herkins, A., Davis, S., Cornish, K. 2025. Development of a circumallergenic guayule latex endotracheal tube cuff. Biomedical Materials & Devices. https://doi.org/10.1007/s44174-024-00274-1.
DOI: https://doi.org/10.1007/s44174-024-00274-1

Interpretive Summary: Circumallergenic guayule latex cuffs were made and used to make a perfect seal between the PVC pleated balloon cuff currently used to hold ventilator tubes in the human trachea. This device will prevent ventilator-associated pneumonia (VAP), caused by bacteria-laden saliva leaked through gthe PVC cuff pleats into the lungs of intubated patients in intensive care units. Currently 8% to 28% of mechanically ventilated patients develop VAP due to leakage through balloon pleats. Treatment costs of VAP are estimated to be between $10,000 and $40,000 per patient in the United States and the mortality rate is 30-70%.

Technical Abstract: Endotracheal tube (ETT) cuffs made from soft, hypoallergenic guayule latex placed outside existing polyvinyl chloride (PVC) cuffs were previously developed as an alternative to PVC cuffs alone. Although these outer cuffs do not cross-react with Type I latex allergy, they were made using conventional vulcanization chemicals which can cause adverse contact reactions. New outer cuffs have been made with guayule latex using a xanthate-based accelerant system designed to avoid contact reactions and create a perfect seal with the patient’s trachea. A standard formula was used for compounding, and concentrations of all components remained constant except for two hypoallergenic accelerants: diisopropyl xanthogen polysulphide (DIXP), added in concentrations of either 2.0 or 2.2 parts per hundred rubber (phr), and zinc diisononyl dithiocarbamate (ZDNC), added in concentration of 0.6, 0.8, or 1.0 phr. Samples were dipped at dwell times of 5 or 15 seconds for thickness variation. Cured samples underwent tensile testing 14 days after creation. Benchtop leak tests were conducted using a standard PVC cuff with three simulated trachea sizes. Additional leak tests were performed using the guayule latex cuffs and a 20 mm inner diameter tube. A combination of 2.0 phr DIXP and 0.6 phr ZDNC resulted in the highest tensile strength in both thin and thick cuffs. The lowest modulus values occurred at 2.0 phr DIXP and 0.8 ZDNC for thinner samples and 2.2 phr DIXP and 1.0 phr ZDNC for thicker samples. The two-way ANOVA for the double cuff leak test revealed no significant effect of accelerant concentration on leakage rate (P = 0.5783). Finally, varying the size of the simulated trachea for the PVC cuffs revealed that larger tracheas had lower average leak rates. All guayule latex double cuffs prevented leakage consistently. The samples made using a combination of 2.0 phr DIXP and 0.6 phr ZDNC had the most ideal mechanical properties (softness, stretchiness, and strength) for the creation of a guayule latex ETT balloon cuff. The decreased leakage rate of the PVC cuff in the larger simulated tracheas was due to the increased room for cuff expansion, reducing the number of longitudinal folds.