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The effect of IV fluids on microcirculation | VETgirl Veterinary CE Podcasts

Parameters were measured as soon as the patient was induced, at 30 and 60 minutes afterwards, and overall. What’d this study find? Overall, this study found that those patients that received 20 mL of LRS/kg/hour had the greatest total and perfused density vessel (in those vessels that were > 20 μm in diameter, which are mostly venules and arterioles).

So what do we take from it? While our healthy patients undergoing elective procedures are at low-risk for hypoperfusion under general anesthesia as compared to our critically ill patients, keep in mind that fluid losses can occur through blood loss, the respiratory tract, and through the abdominal cavity. When these fluid losses occur in the face of anesthetic drugs, there is the risk of poor perfusion. And you know a criticalist’s favorite answer to every veterinary question out there: perfusion and metabolic acidosis, right?

“When we monitor a patient’s blood pressure or oxygen levels, we’re not always able to discern what is happening at the cellular level,” Silverstein said. “Sometimes there are tissues and cells that are getting a surplus of oxygen while other cells or tissues are in need of more, but our measuring the big things, like blood pressure, doesn’t tell us that. The only way we figure that out is when the patient develops organ dysfunction or new complications arise following anesthesia.”

The American Animal Hospital Association and American Association of Feline Practitioners recommend the use of IV fluids in their guidelines under even routine procedures. While it adds to the cost of surgery (well, barely), it’s worth it. Based on this study, it may improve the microcirculation in our anesthetized patients!

“The larger vessels are the ones that are constricting and dilating to feed the microcirculation,” Silverstein said. “And it appears that the animals that got the highest rate of fluids in this study — which may not be the optimal rate — are the ones that seemed to have the greatest recruitment of arterioles and venules.”

For more information, check out Penn News.

References:

1. Silverstein DC, Cozzi EM, Hopkins AS. Microcirculatory effects of intravenous fluid administration in anesthetized dogs undergoing elective ovariohysterectomy. Am J Vet Res 2014;75(9):809-817.

2. Keane PW, Murray PF. Intravenous fluids in minor surgery. Their effect on recovery from anaesthesia. Anaesthesia 1986;41:635–637.

3. Terry RN, Trudnowski RJ. Intraoperative fluid therapy: relationship to anesthetic and surgical complications. N Y State J Med 1964;64:2646–2654.

4. Trinooson CD, Gold ME. Impact of goal-direct perioperative fluid management in high-risk surgical procedures: A literature review. AANA Journal 2013;81(5):357-368.

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