Isoflurane sparing and the influence on cardiovascular and pulmonary parameters through a continuous romifidine hydrochloride infusion during general anaesthesia in horses - a clinical study

Abstract

ZusammenfassungIn einer Doppelblindstudie an 20 Pferden (Gruppe I: Körpermasse Ø 488 ± 90 kg, Alter 5 ± 4 J; Gruppe II: Körpermasse Ø 545 ±160 kg, Alter 5,5 ± 5 J) sollte die Wirkung von Romifidinhydrochlorid (Sedivet®, Boehringer Ingelheim) auf die Inhalationsnarkose mit Isofluran untersucht werden. Ziel der Untersuchung war es, bei elektiven Eingriffen unter Allgemeinanästhesie die Beeinflussung der IsofluranMenge durch die kontinuierliche Verabreichung von Romifidin in der Dosierung von 0,3 µg kg -1 min zu prüfen. Des weiteren sollte untersucht werden, ob die zusätzliche Applikation des Sedativums zu einer Beeinflussung relevanter kardiovaskulärer und pulmonaler Parameter führt. Kontinuierlich aufgezeichnet und statistisch ausgewertet wurden die exspiratorische Isoflurankonzentration (exsp.Iso.), der mittlere arterielle Blutdruck (m a BD.), die Herzfrequenz (HF), das Atemminutenvolumen (AMV), das Atemzugvolumen (AZV) und der endexspiratorische Kohlendioxidgehalt (Et CO 2 ). Alle 15 Minuten wurde der arterielle Kohlendioxidpartialdruck (P a CO 2 ) sowie der arterielle Sauerstoffpartialdruck (P a O 2 ) und der Blut-pH-Wert gemessen. Die Parameter AMV, AZV, P a O 2 und Blut-pH zeigten keine signifikanten Unterschiede im Vergleich der beiden Gruppen. Die Pferde, denen Romifidin als Dauertropfinfusion verabreicht wurde, zeigten im Vergleich zur Kontrollgruppe eine signifikante Reduktion der inspiratorischen Isoflurankonzentration (p р 0,05). Außerdem kam es in der Romifidin-Gruppe zu einer deutlich geringeren Beeinflussung des maBP (p р 0,05). Dies zeigte sich auch daran, dass die Pferde der Kontrollgruppe deutlich öfter Dobutamin zur Stützung kardiovaskulärer Funktionen benötigten (p р 0,05). Die kontinuierliche Verabreichung von Romifidin führte zu einer positiven Beinflussung der kardiovaskulären und pulmonalen Parameter während einer Isofluran-Narkose. Der Verbrauch an Isofluran konnte durch die Romifidin-Infusion deutlich verringert werden.Schlüsselwörter: Pferd, Narkose, Isofluran, Romifidin, Narkoserisiko Isoflurane sparing and the influence on cardiovascular and pulmonary parameters through a continuous romifidine hydrochloride infusion during general anaesthesia in horses -a clinical studyIn a double-blinded study of 20 horses (Group I: body mass Ø 488 ± 90 kg, age 5 ± 4 years; Group II: body mass Ø 545 ±160 kg, age 5.5 ± 5 years) the synergistic effect of romifidine hydrochloride (Sedivet ® , Boehringer Ingelheim) on the inhalation anaesthesia with isoflurane was examined. The objective of the investigation was to measure the effect of a continuous administration of romifidine (0,3 µg kg-1 min) on the isoflurane amount consumed during general anaesthesia in elective surgery cases. Furthermore, the influence of the additional sedative on relevant cardiovascular and pulmonary parameters was examined. Exhaled isoflurane concentration, medium arterial blood pressure (m a BP), heart rate (HR), breath per minute volume (BPM), tidal volume (TV) and the end-expiratory carbon dioxide content (Et CO 2 ) were noted...

Effects of a constant rate infusion of detomidine on cardiovascular function, isoflurane requirements and recovery quality in horses

“…Cardiac index (CI) was not measured in the latter study. In contrast with the results of Kuhn et al. (2004), a CRI of the same α 2 ‐agonist (romifidine 40 μg kg −1 hour −1 ) did not affect cardiovascular function (including CI), isoflurane requirement or recovery quality in isoflurane anaesthetized horses undergoing elective surgery (Devisscher et al.…”

“…The ‘ideal’ balanced anaesthetic technique has not been found and although it would be incorrect to label any combination of an inhalant with an intravenous anaesthetic as balanced anaesthesia, the advantage of these combinations in horses has been clearly suggested (Neges et al. 2003; Kuhn et al. 2004; Kushiro et al.…”

“…Reports on the effects of CRI’s of different α 2 ‐agonists remain somewhat contradictory, particularly in clinically based studies where often (but not always) cardiovascular monitoring is limited to blood pressure and heart rate, and does not include cardiac output and resultant calculations of oxygen delivery. A CRI of romifidine (18 μg kg −1 hour −1 ) infused during isoflurane anaesthesia in horses induced a significant reduction in the expiratory isoflurane concentration, a better preserved blood pressure and a reduced need for dobutamine and mechanical ventilation of the lungs compared to the placebo group (Kuhn et al. 2004).…”

Effects of a constant‐rate infusion of dexmedetomidine on the minimal alveolar concentration of sevoflurane in ponies

“…Single boluses of xylazine reduced the MAC of isoflurane [2] and halothane [21]. A romifidine CRI significantly reduced the expiratory isoflurane concentration in one clinical study [6], whereas another failed to find a clear reduction of the anaesthetic requirement [7]. Detomidine reduced the MAC of halothane by 33% when infused continuously [3], although no reduction was found in isoflurane‐anaesthetised horses [8].…”

The Effects of Dexmedetomidine Continuous Rate Infusion (CRI) on Isoflurane Anaesthesia in Healthy Horses

“…According to Kuhn et al [9] a CRI of 18 µg•kg −1 •hour −1 after initial dose of 80 µg•kg −1 caused a significant reduction in concentration of inhaled agent with improved cardiovascural and respiratory parameters. In contrast, Devisscher et al [10] failed to detect neither inhalation sparing effect nor better cardiopulmonary function and recovery quality, when using the same loading dose of romifidine followed by a CRI at 40 µg•kg −1 •hour −1 .…”