Causes, Effects and Methods of Monitoring Gas Exchange Disturbances during Equine General Anaesthesia

Abstract

Horses, due to their unique anatomy and physiology, are particularly prone to intraoperative cardiopulmonary disorders. In dorsally recumbent horses, chest wall movement is restricted and the lungs are compressed by the abdominal organs, leading to the collapse of the alveoli. This results in hypoventilation, leading to hypercapnia and respiratory acidosis as well as impaired tissue oxygen supply (hypoxia). The most common mechanisms disturbing gas exchange are hypoventilation, atelectasis, ventilation–perfusion (V/Q) mismatch and shunt. Gas exchange disturbances are considered to be an important factor contributing to the high anaesthetic mortality rate and numerous post-anaesthetic side effects. Current monitoring methods, such as a pulse oximetry, capnography, arterial blood gas measurements and spirometry, may not be sufficient by themselves, and only in combination with each other can they provide extensive information about the condition of the patient. A new, promising, complementary method is near-infrared spectroscopy (NIRS). The purpose of this article is to review the negative effect of general anaesthesia on the gas exchange in horses and describe the post-operative complications resulting from it. Understanding the changes that occur during general anaesthesia and the factors that affect them, as well as improving gas monitoring techniques, can improve the post-aesthetic survival rate and minimize post-operative complications.

Peri-anesthetic Environmental and Occupational Exposure to Desflurane Waste Anesthetic Gas in a Large Animal Veterinary Hospital

“…Horses commonly hypoventilate under general anesthesia, and at the start of the recovery phase, breathing can be shallow and less desflurane may be exhaled. 22 The effort to stand following a period of general anesthesia and recumbency often requires significant physical effort and increase in respiratory effort. It is then possible that an increased amount of desflurane WAG could be observed following resumption of the standing position due to increased elimination of desflurane.…”

“…This difference may be due to changes in the respiratory and ventilatory patterns of horses emerging from general anesthesia. Horses commonly hypoventilate under general anesthesia, and at the start of the recovery phase, breathing can be shallow and less desflurane may be exhaled 22 . The effort to stand following a period of general anesthesia and recumbency often requires significant physical effort and increase in respiratory effort.…”

Identificación de agentes micóticos (Aspergillus spp. y Candida spp.) en equipos respiratorios de uso veterinario

“…La función de estos tubos es entregar los gases anestésicos y el oxígeno al paciente, asegurando un suministro adecuado para mantener al paciente sedado y respirando correctamente durante la intervención (Stefanik et al, 2021). Los hongos pueden encontrar condiciones favorables para su crecimiento y supervivencia en dichos tubos, ya que pueden ser expuestos a humedad y residuos orgánicos (Hemati et al, 2021).…”