Traumatic perforation of the trachea in two horses caused by orotracheal intubation

Methods Used for Endotracheal Tube Cuff Inflation and Pressure Verification in Veterinary Medicine: A Questionnaire on Current Practice

Endotracheal intubation is a routine procedure in veterinary anaesthesia, yet no consensus guidelines exist for endotracheal tube (ETT) cuff inflation and pressure measurement. The aim of this study was to assess current practice of ETT cuff inflation and seal verification in veterinary medicine. An online questionnaire was distributed among veterinary professionals who administer anaesthesia, comprising six demographic and twelve ETT cuff-related questions per species. N = 348 questionnaires were completed. Cuff pressure was measured by 30% of respondents in cats, 32% in dogs and 9% in both farm animals and horses. Anaesthesia diplomates were not more likely to measure cuff pressure than others, except in cats (OR: 1.8; 95% CI: 1.1−2.9). The most frequently selected recommended range of cuff pressure was 20−30 cm H2O, regardless of species, although >30 cm H2O was selected significantly more often in horses compared to dogs, cats and farm animals. The preferred technique to verify cuff seal was minimal occlusive volume in dogs, cats and farm animals, whereas in horses, the preferred method was verification of normal capnogram waveform. ETT cuff pressure measurement remains uncommon in veterinary anaesthesia. The development of consensus recommendations for cuff inflation, including evidence-based target cuff pressure ranges for various species and different ETT models or materials, can help to improve practice.

Impact of endotracheal tube size and cuff pressure on tracheal and laryngeal mucosa of adult horses

OBJECTIVE

To assess the effects of two sizes of silicone endotracheal tubes with internal diameter 26 mm (ETT₂₆) and 30 mm (ETT₃₀) inflated to minimum occlusive volume on tracheal and laryngeal mucosa of adult horses anesthetized for 2 hours with isoflurane.

STUDY DESIGN

Prospective, randomized, blinded, crossover experimental study.

ANIMALS

A total of eight healthy adult mares.

METHODS

Upper airway endoscopy and ultrasound measurements of internal tracheal diameter were performed the day before anesthesia. Horses were anesthetized and orotracheally intubated with ETT₂₆ or ETT₃₀. Ease of intubation was scored. The cuff was inflated in 10 mL increments to produce a seal. Final volume of air used and intracuff (IC) pressure (measured by pressure transducer) were recorded. At the end of anesthesia, a manometer was used to measure IC pressure and these measurements compared against measurements from the pressure transducer. Laryngeal and tracheal mucosa were assessed via endoscopy and assigned a score 0-3 before anesthesia, and at 2 and 24 hours following extubation.

RESULTS

Data are from seven horses because one horse with laryngeal hemiplegia was excluded. Mean tracheal ultrasound measurement was 3.5 ± 0.4 cm. No significant differences were noted between endotracheal tube sizes for intubation score, IC pressures, inflation volumes or tracheal or laryngeal injury scores at any time point. IC pressure measured by manometer was slightly higher than that by transducer (+1.0 ± 2.8 mmHg).

CONCLUSIONS AND CLINICAL RELEVANCE

Results identified no clear advantage of one endotracheal tube size over the other in the population of horses studied, when endotracheal intubation is properly applied and IC pressure is carefully monitored. However, given that ETT₂₆ was associated with the highest observed IC pressures and the only observed incidents of tracheal circumferential erythema, the larger ETT₃₀ may be the better choice in most cases where tracheal size is sufficient.