Comparison of respiratory function during TIVA (romifidine, ketamine, midazolam) and isoflurane anaesthesia in spontaneously breathing ponies Part I: blood gas analysis and cardiorespiratory variables. (7th August 2014)

• Record Type: Journal Article
• Authors: Steblaj, Barbara; Schauvliege, Stijn; Pavlidou, Kiriaki; Gasthuys, Frank; Savvas, Ioannis; Duchateau, Luc; Kowalczk, Lidia; Moens, Yves
• Is Part Of: Veterinary anaesthesia and analgesia. Volume 41:Number 6(2014:Nov.)
• Page Start: 583
• Page End: 591
• Publication Date: 2014-08-07
• Subjects: Veterinary anesthesia -- Periodicals; 636.089
• DOI: 10.1111/vaa.12167
• Languages: English
• ISSNs: 1467-2987

Abstract

<abstract abstract-type="main" id="vaa12167-abs-0001"> <title>Abstract</title> <sec id="vaa12167-sec-0001" sec-type="section"> <title>Objective</title> <p>To compare pulmonary function and gas exchange in ponies during maintenance of anaesthesia with isoflurane or by a total intravenous anaesthesia (TIVA) technique.</p> </sec> <sec id="vaa12167-sec-0002" sec-type="section"> <title>Study design</title> <p>Experimental, cross–over study.</p> </sec> <sec id="vaa12167-sec-0003" sec-type="section"> <title>Animals</title> <p>Six healthy ponies weighing mean 286 (range 233–388) ± SD 61 kg, age 13 (9−16) ± 3 years.</p> </sec> <sec id="vaa12167-sec-0004" sec-type="section"> <title>Methods</title> <p>The ponies were anaesthetized twice, a minimum of two weeks apart. Following sedation with romifidine [80 μg kg<sup>−1</sup> intravenously (IV)], anaesthesia was induced IV with midazolam (0.06 mg kg<sup>−1</sup>) and ketamine (2.5 mg kg<sup>−1</sup>), then maintained either with inhaled isoflurane (F<sc>e</sc>′Iso = 1.1 vol%) (T‐ISO) or an IV infusion of romifidine (120 μg kg<sup>−1</sup> hour<sup>−1</sup>), midazolam (0.09 mg kg<sup>−1</sup> hour<sup>−1</sup> IV) and ketamine (3.3 mg kg<sup>−1</sup> hour<sup>−1</sup>) (T‐TIVA). Ponies were placed in lateral recumbency. Breathing was spontaneous and Fi′O<sub>2</sub> 60%. After an instrumentation/stabilisation period of 30 minutes, arterial and mixed venous blood samples were taken simultaneously every 10 minutes for 60 minutes and analysed immediately. Oxygen extraction ratio (O<sub>2</sub>ER) and venous admixture were calculated. Tidal volume (TV), minute volume (MV), respiratory rate (f<sub>R</sub>), packed cell volume (PCV), arterial blood pressure and heart rate (HR) were measured and recorded. Data were analysed with mixed model <sc>anova</sc> (α = 0.05). Treatments were compared overall and at two selected time points (T30 and T60) using Bonferroni correction.</p> </sec> <sec id="vaa12167-sec-0005" sec-type="section"> <title>Results</title> <p>Arterial and mixed venous partial pressures of O<sub>2</sub> and CO<sub>2</sub>, and TV were significantly lower and MV and f<sub>R</sub> were higher in T‐TIVA compared to T‐ISO. Venous admixture did not differ between treatments. O<sub>2</sub>ER was significantly higher in T‐TIVA. Mean arterial pressure was higher and HR was lower in T‐TIVA compared to T‐ISO.</p> </sec> <sec id="vaa12167-sec-0006" sec-type="section"> <title>Conclusions and clinical relevance</title> <p>Whilst arterial CO<sub>2</sub> was within an acceptable range during both protocols, the impairment of oxygenation was more pronounced with the T‐TIVA evidenced by lower arterial and venous oxygen partial pressures.</p> </sec> </abstract>