Evaluation of Endotracheal Tube Cuff Pressure and the Use of Three Cuff Inflation Syringe Devices in Dogs

Wan-Chu Hung, Purdue University

Abstract

Endotracheal intubation is a routine and necessary safety procedure during inhalant anesthesia. The endotracheal tube (ETT) cuff provides a tight seal between the endotracheal wall and the tube to prevent leakage of waste anesthetic gas and aspiration of foreign materials. Both under- and over- inflations of the ETT cuff pose risks to animals under general anesthesia. Underinflation of the ETT cuff predisposes animals to aspiration of regurgitant or gastric secretions when regurgitation occurs. It also allows the escape of anesthetic gas from the airway which may lead to difficulty in maintaining the appropriate depth of anesthesia and pollution of the operative environment. Over-inflation of the ETT cuff can impede blood circulation of the tracheal mucosa and result in tracheal damage or tracheal necrosis. Review of published veterinary anesthesia monitoring guidelines reveals that there is no standardized recommendation of routine monitoring ETT cuff pressure in anesthetized patients. The incidence of over- or under-inflation of the ETT cuff in the anesthetized dogs remains unknown. Therefore, the objectives of this two-phase prospective study were 1) to determine the incidence of over- and under-inflation of the ETT cuff in the anesthetized dogs at Purdue Veterinary Medical Teaching Hospital (PVMTH) and 2) to evaluate the performance of three different commercially available syringe devices (a regular injectable syringe, Tru-Cuff™ syringe and AG Cuffill syringe) in inflating the ETT cuff to a recommended safe cuff pressure range (20 to 30 cmH2O). Besides these two objectives, we also evaluated the ETT cuff pressure changes over time with spontaneous or mechanical ventilation, as well as the effect of body position change on the ETT cuff pressure change. In addition, we investigated a group of dogs that did not require the initial ETT cuff inflation after endotracheal intubation. We hypothesized that there was a high incidence of improper inflation of the ETT cuff in the anesthetized dogs at PVMTH. We also hypothesized that the use of one of the commercially available cuff inflation syringe devices (TruCuff™ syringe and AG Cuffill syringe) would help reduce the incidence of improper inflation of the ETT cuff compared to using a regular injectable syringe. This study was approved by the Purdue Animal Care and Use Committee (PACUC) (Protocol number: 1804001729). To evaluate the incidence of over- and under-inflation of the ETT cuff (objective one), a total of 80 dogs undergoing general anesthesia at PVMTH between June and August 2018 were enrolled in the Phase One study. Only dogs intubated with SurgiVet® silicone cuffed endotracheal tubes without wire enforcement were included. The ETT selection and cuff inflation followed the PVMTH’s standard operating procedures (SOP). The SOP for ETT cuff inflation includes a leak test and the application of minimum occlusive volume (MOV) technique with a regular injectable syringe. The leak test is carried out by closing the pop-off valve of the breathing circuit of an anesthetic machine and compressing the reservoir bag to a peak airway pressure of 20 cmH2O. At the same time, the noise of air leakage is checked by listening closely to the dog’s airway. If there is an audible air leakage, the MOV technique is carried out by gradually inflating the ETT cuff with a regular injectable syringe to determine the minimal volume of air required to prevent air leakage from the trachea.

Degree

M.Sc.

Advisors

Ko, Purdue University.

Subject Area

Veterinary services|Medicine|Plastics|Surgery

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