Complications in Equine Surgery. Группа авторов
for 3 min, and repeating this sequence 3 times), led to lower serum lactate concentration and CO2 and less hypotension and bradycardia following the release compared to a standard quick removal of the tourniquet [108].
There are no published reports of fatalities as a consequence of IVRA or intravenous regional limb perfusion in horses, which indicates that it is probably a very safe technique. A mild and transient decrease in blood pressure is usually observed in the experience of the author after the release of a tourniquet in horses under general anesthesia.
Prevention
The absolute safe limit of tourniquet duration has not been established and may depend on location and vary from animal to animal. The usual clinical recommendation is to limit the time of tourniquet to 2 hours, although in the author’s clinical experience this time has sometimes been exceeded with no negative consequences. In experimental rhesus monkeys, the systemic changes produced as a result of the application of a tourniquet for periods of up to 3 hours were not marked and readily reversible, and the local acid–base changes in the ischemic limb recovered in less than 40 min post‐release [111]. However, it should be noted that these were healthy animals, and shorter tourniquet times are recommended in debilitated animals.
It is recommended to use a staggered tourniquet release, which will both avoid a sudden release of local anesthetic into the systemic circulation and will reduce the cardiovascular consequences of limb reperfusion.
Diagnosis
The clinical manifestations of tourniquet release may include hypotension, brady‐ or tachy‐cardia, arrhyhtmias, tachypnea, and in extreme cases cardiovascular collapse or cardiac arrest. Close monitoring of the cardiovascular system is therefore recommended during and at least 30–40 min following tourniquet release.
Treatment
In healthy animals and when the cardiovascular changes are mild, no treatment is necessary. In cases of severe hypotension or cardiovascular collapse, supportive treatment with intravenous fluids, positive inotropic drugs (e.g. dobutamine) and/or vasoconstrictors (e.g. phenylephrine) may be necessary. Also, a venous blood sample should be obtained to check acid–base balance and serum electrolytes, and treat derangements (e.g. hyperkalemia, hypercalcemia) as necessary.
Expected outcome
The outcome is good if the cardiovascular effects are mild, but it could be fatal if cardiovascular collapse or cardiac arrest occur.
References
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