Tourniquet-induced hypertension in a horse.

This research article deals with a case of arterial hypertension in a horse that occurred as a result of using a tourniquet during surgery. The changes in the horse’s heart rate and arterial pressure as a consequence of the tourniquet application and its subsequent removal are discussed.

Summary of the Case

• The research revolves around a horse who underwent surgery for an inflamed right carpal joint. The horse was anesthetized using a combination of xylazine HCl, butorphanol, guaifenesin, and thiamylal Na, with the continued use of halothane in oxygen to maintain the anesthesia.
• About 15 minutes after the placement of a pneumatic tourniquet above the horse’s right carpus, the horse started showing signs of arterial hypertension (high blood pressure) and tachycardia (increased heart rate). The tourniquet was inflated to a pressure of 800 mm Hg.

Surgical Adjustments and Outcome

• In response to the sudden development of hypertension and tachycardia, the surgery was expedited and the anesthetic was changed. Halothane was discontinued and guaifenesin was used instead to further anaesthetize the horse and help with bandaging.
• The horse’s heart rate showed significant reduction – from 72 beats per minute down to 42 beats per minute after the tourniquet was deflated. The mean arterial pressure also fell significantly, from 260 mm of Hg to 128 mm of Hg.

Possible Causes for Hypertension During Anesthesia

• The rise in blood pressure during anesthesia could be due to various factors. The article mentions a number of differential diagnoses for rapidly increasing arterial pressure during halothane anesthesia. These include inadequate depth of anesthesia, indications of pain, hypercapnia (elevated carbon dioxide levels in the blood), hypoxemia (low blood oxygen levels), and/or hyperthermia (overheating).