Frontiers in veterinary science2020; 7; 601326; doi: 10.3389/fvets.2020.601326

Changes in Arterial Blood Pressure and Oxygen Tension as a Result of Hoisting in Isoflurane Anesthetized Healthy Adult Horses.

Cerullo, M
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Driessen, B
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Douglas, H
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Hopster, K

Abstract: In anesthetized adult horses, changes in recumbency can influence the cardiovascular system but how arterial blood pressures and oxygen tension change in isoflurane anesthetized animals as a direct result of hoisting has not been investigated. To evaluate effects of hoisting on hemodynamic function and pulmonary gas exchange in isoflurane-anesthetized horses. Prospective, experimental study. Six adult horses were anesthetized three times using isoflurane in pure oxygen (inspired fraction 0.9-1.0), and allowed breathing spontaneously in lateral recumbency. After 45 min horses were hoisted using a single hoist-hobble system for 5 min and returned into left lateral recumbency. Heart rate (HR), respiratory rate (RR), and systolic (SAP), diastolic (DAP), and mean arterial blood pressures (MAP) were measured every minute starting from 5 min before to 5 min after hoisting. Arterial blood gas samples were collected before, during, and after hoisting. Significant changes in hemodynamic parameters and PaO but not PaCO were found between baseline recordings and measurements obtained during and early after hoisting. The MAP decreased within the 1st min of hoisting from a mean of 74 ± 17 mmHg at baseline to 57 ± 20 mmHg ( < 0.05). Thereafter, it rapidly recovered to baseline before continuing to rise to higher than baseline values and then remaining elevated for 5 min after horses were returned into lateral recumbency. Simultaneously, the HR increased by 6-9 beats per min during the initial 3 min of hoisting before returning close to baseline values ( < 0.05). The PaO decreased significantly from a mean of 324.9 ±137.0 mmHg at baseline to a mean of 141.3 ± 104.2 mmHg during hoisting ( < 0.001) without recovering any more to baseline values. Hoisting an adult horse during or at the end of isoflurane anesthesia carries the risk of a precipitous, though short-lived (1-2 min), drop in arterial blood pressures and a persistent decrease in arterial oxygenation. While in systemically healthy animals the observed functional impairments were not life-threatening, they may be more severe in systemically compromised horses.Therefore, arterial blood pressures and oxygenation must be carefully monitored when hoisting sick equine patients during or at the end of inhalant anesthesia.

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Publication Date: 2020-11-25 PubMed ID: 33324704PubMed Central: PMC7723898DOI: 10.3389/fvets.2020.601326Google Scholar: Lookup

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Summary

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This research investigates the effects of hoisting on the cardiovascular system and pulmonary gas exchange in horses under isoflurane anesthesia. It was found that hoisting a horse during or at the end of this type of anesthesia can cause a significant, though temporary, drop in arterial blood pressures and a lasting decrease in oxygen levels.

Study Design

This study was designed as a prospective, experimental trial involving six adult horses. Each horse was anesthetized three times using isoflurane in pure oxygen and allowed to breathe spontaneously in a lateral position.
After 45 minutes, the horses were hoisted using a single hoist-hobble system for 5 minutes and then returned to the left lateral position. During this period, the heart rate, respiratory rate, and various arterial blood pressures were recorded.
Arterial blood gas samples were collected before, during, and after hoisting to measure changes in the oxygen and carbon dioxide content in the blood.

Findings

The researchers found significant changes in hemodynamic parameters and oxygen concentration, but not carbon dioxide concentration, between baseline measurements and those taken during and immediately after hoisting.
Within the first minute of hoisting, mean arterial blood pressure dropped significantly from a baseline of 74 ± 17 mmHg to 57 ± 20 mmHg. However, this quickly returned to baseline levels before rising to higher values and then stabilizing at an elevated level for 5 minutes after the horses were returned to lateral recumbency.
The heart rate increased by 6-9 beats per minute during the initial 3 minutes of hoisting before returning to near baseline levels.
The oxygen tension in the blood decreased significantly from a baseline of 324.9 ±137.0 mmHg to a mean of 141.3 ± 104.2 mmHg during hoisting. Unlike the blood pressure, the oxygen tension did not recover to baseline levels.

Conclusion

The findings suggest that hoisting a horse during or at the end of isoflurane anesthesia can cause a significant, though short-lived, drop in blood pressure and a persistent decrease in blood oxygen levels.
While these changes were not life-threatening in healthy horses, they may lead to more severe complications in horses that are systemically compromised.
As a result, it is crucial to monitor arterial blood pressures and blood oxygen levels closely when hoisting equine patients during or at the end of inhalant anesthesia.

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APA

Cerullo M, Driessen B, Douglas H, Hopster K. (2020). Changes in Arterial Blood Pressure and Oxygen Tension as a Result of Hoisting in Isoflurane Anesthetized Healthy Adult Horses. Front Vet Sci, 7, 601326. https://doi.org/10.3389/fvets.2020.601326