The cardiopulmonary effects of dexmedetomidine infusions in dogs during isoflurane anesthesia. (31st July 2014)

• Record Type: Journal Article
• Authors: Pascoe, Peter J
• Is Part Of: Veterinary anaesthesia and analgesia. Volume 42:Number 4(2015:Jul.)
• Page Start: 360
• Page End: 368
• Publication Date: 2014-07-31
• Subjects: Veterinary anesthesia -- Periodicals; 636.089
• DOI: 10.1111/vaa.12220
• Languages: English
• ISSNs: 1467-2987

Abstract

<abstract abstract-type="main" id="vaa12220-abs-0001"> <title>Abstract</title> <sec id="vaa12220-sec-0001" sec-type="section"> <title>Objective</title> <p>To determine the cardiopulmonary changes associated with intravenous (IV) infusions of dexmedetomidine at equipotent isoflurane‐dexmedetomidine concentrations compared with isoflurane alone.</p> </sec> <sec id="vaa12220-sec-0002" sec-type="section"> <title>Study design</title> <p>Prospective, randomized, crossover experiment.</p> </sec> <sec id="vaa12220-sec-0003" sec-type="section"> <title>Animals</title> <p>Six adult intact female mixed‐breed dogs weighing (mean ± SD [range]) 23.3 ± 3.8 (17.8–29.4) kg.</p> </sec> <sec id="vaa12220-sec-0004" sec-type="section"> <title>Methods</title> <p>Anesthesia was induced and maintained with isoflurane in oxygen. Measurements of respiratory rate (<italic>f</italic><sub>R</sub>), heart rate (HR), systemic and pulmonary arterial pressures (SAP, DAP, MAP, MPAP), central venous pressure (CVP), pulmonary arterial occlusion pressure (PAOP), cardiac index (CI), left and right ventricular stroke work index (LVSWI, RVSWI), systemic and pulmonary vascular resistance index (SVRI, PVRI), arteriovenous shunt (<inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgjrmnjr4r" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="urn:x-wiley:14672987:media:vaa12220:vaa12220-math-0001" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover accent="true"><mml:mi mathvariant="normal">Q</mml:mi><mml:mo>˙</mml:mo></mml:mover><mml:mi mathvariant="normal">s</mml:mi><mml:mo stretchy="false">/</mml:mo><mml:mover accent="true"><mml:mi mathvariant="normal">Q</mml:mi><mml:mo>˙</mml:mo></mml:mover><mml:mi mathvariant="normal">t</mml:mi></mml:mrow></mml:math></alternatives></inline-formula>), oxygen delivery (<inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgjrmnjr58" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="urn:x-wiley:14672987:media:vaa12220:vaa12220-math-0002" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover accent="true"><mml:mi mathvariant="normal">D</mml:mi><mml:mo>˙</mml:mo></mml:mover><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math></alternatives></inline-formula>), oxygen extraction ratio (O<sub>2</sub>ER), oxygen consumption, arterial and mixed venous blood gases, and arterial packed cell volume (PCV) were obtained 30 minutes after instrumentation at an end‐tidal isoflurane concentration (F<sc>e</sc>′Iso) of 1.73 ± 0.02% (1.3 MAC). Dexmedetomidine was administered IV at 0.5 or 3 μg kg<sup>−1</sup> over 6 minutes followed by an infusion at 0.5 (LD) or 3 μg kg<sup>−1</sup> hour<sup>−1</sup> (HD), respectively, with F<sc>e</sc>′Iso at 1.41 ± 0.02 (LD) or 0.72 ± 0.09% (HD). Measurements were taken at 10, 30, 60, 90, 120, 150 and 180 minutes after the start of the infusion.</p> </sec> <sec id="vaa12220-sec-0005" sec-type="section"> <title>Results</title> <p>The low dose produced significant decreases in HR, increases in SAP, DAP, CVP, MPAP, PAOP and LVSWI, but no change in CI. HD produced significant increases in SAP, MAP, DAP, CVP, PAOP, SVRI, LVSWI, O<sub>2</sub>ER and PCV and significant decreases in CI and <inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgjrmnjr2q" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="urn:x-wiley:14672987:media:vaa12220:vaa12220-math-0003" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover accent="true"><mml:mi mathvariant="normal">D</mml:mi><mml:mo>˙</mml:mo></mml:mover><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math></alternatives></inline-formula>. There were significant differences between treatments in HR, MAP, DAP, CVP, MPAP, PAOP, CI, SVRI, <inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgjrmnjr37" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="urn:x-wiley:14672987:media:vaa12220:vaa12220-math-0004" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msubsup><mml:mtext>HCO</mml:mtext><mml:mn>3</mml:mn><mml:mo>−</mml:mo></mml:msubsup></mml:math></alternatives></inline-formula>, SBE, <inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgjrmnjr0p" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="urn:x-wiley:14672987:media:vaa12220:vaa12220-math-0005" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover accent="true"><mml:mi mathvariant="normal">D</mml:mi><mml:mo>˙</mml:mo></mml:mover><mml:msub><mml:mi mathvariant="normal">O</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:mrow></mml:math></alternatives></inline-formula>, O<sub>2</sub>ER and <inline-formula><alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgjrmnjr16" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math altimg="urn:x-wiley:14672987:media:vaa12220:vaa12220-math-0006" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mover accent="true"><mml:mi mathvariant="normal">Q</mml:mi><mml:mo>˙</mml:mo></mml:mover><mml:mi mathvariant="normal">s</mml:mi><mml:mo stretchy="false">/</mml:mo><mml:mover accent="true"><mml:mi mathvariant="normal">Q</mml:mi><mml:mo>˙</mml:mo></mml:mover><mml:mi mathvariant="normal">t</mml:mi></mml:mrow></mml:math></alternatives></inline-formula>.</p> </sec> <sec id="vaa12220-sec-0006" sec-type="section"> <title>Conclusions and clinical relevance</title> <p>Cardiopulmonary changes associated with LD were within clinically accepted normal ranges whereas HD produced clinically significant changes. The LD may be useful as an anesthetic adjunct in healthy dogs.</p> </sec> </abstract>