Evaluation of accuracy of invasive and non-invasive blood pressure monitoring in relation to carotid artery pressure in anaesthetised ponies

Invasive blood pressure measurement (IBP) using peripheral arteries is a commonly used technique in equine anaesthesia, although the accuracy has not been demonstrated. Non-invasive blood pressure monitoring (NIBP) may be indicated for field anesthesia, short procedures and foal anaesthesia. In the present report, the agreement of various IBP and NIBP measuring sites compared to carotid artery pressure was tested in anaesthetised experimental ponies. Six ponies were anaesthetised in lateral recumbency with sevoflurane and received either saline or dexmedetomidine boli followed by constant rate infusion (CRI). Invasive blood pressure measurements were obtained simultaneously from the carotid, facial and metatarsal arteries. NIBP measurements over both median arteries, metatarsal and middle coccygeal arteries were performed in random order. All blood pressure readings obtained were compared to carotid pressure by Bland-Altman analysis. Non-invasive blood pressure measurements had larger bias and poorer limits of agreement compared to IBP measurements. NIBP measurement from the coccygeal artery had the best repeatability and best limits of agreement of all NIBP positions and was not affected by the use of dexmedetomidine. The facial artery had smaller limits of agreement with dexmedetomidine treatment. There was no difference between the facial and metatarsal arteries during dexmedetomidine treatment in MAP and DAP. Systolic arterial pressures from the metatarsal artery showed larger bias and larger limits of agreement compared to facial artery. In conclusion, NIBP measurement from the tail artery is a reliable alternative to direct arterial blood pressure measurement. Both the metatarsal and facial arteries have acceptable agreement with carotid artery pressure so the choice can be based on the logistics of the procedure

A method comparison study of invasive blood pressure and noninvasive blood pressure measurement in isoflurane-anaesthetized horses performed with Cardiocap™ and the oscillometric device Sentinel

Ziele: Beurteilung der Genauigkeit des nicht invasiven Blutdruckes (NIBP) gemessen mit dem oszillometrischen Monitor Sentinel im Vergleich zum invasiven Blutdruck (IBP) gemessen mit Cardiocap bei Pferden in Anästhesie. Zu untersuchen, ob Unterschiede zwischen Sentinel und Cardiocap assoziert sind mit der Lage bzw dem Gewicht der Pferde, der Position der Blutdruckmanschetten oder Azepromazin Prämedikation. Studiendesign: Prospektive Studie Tiere: 29 Pferde Methoden: IBP wurde via Katheter in der Facial-, Transversal- oder Metatarsalarterie gemessen. NIBP wurde mittels passender Blutdruckmanschetten über den Röhrbeinen oder dem Schweif erfasst. Ein gemischtes Model verglich die Blutdruckwerte des IPB und NIBP und schätzte den Einfluss von Position des arteriellen Katheters, Platzierung der Blutdruckmanschetten und die Kombination von Lage, Gewicht des Pferdes oder Azepromazin Prämedikation ein. Resultate: Sentinel tendierte zu höheren Messungen als der Cardiocap. Die Genauigkeit von Sentinel varierte mit der Lage der Pferde und der Position der Blutdruckmanschetten. Klinische Relevanz: Obwohl Sentinel eine höhere Variabilität zeigte im Vergleich zum Cardiocap, ist die NIBP Messmethode eine angemessene Alternative um den Blutdruck unter Feldbedingungen zu messen. Objective: To assess the accuracy of the noninvasive blood pressure (NIBP) measured by the oscillometric device Sentinel compared to the invasive blood pressure (IBP) measured by Cardiocap in anaesthetized horses undergoing surgery. To assess if differences between the Sentinel and Cardiocap are associated with recumbency, cuff placement, weight of the horse or acepromazine premedication and to describe the usefulness of Sentinel. Study design: Prospective method comparison study. Animals: Twenty-nine horses. Methods: IBP was measured via a catheter in the facial artery, transverse facial artery or metatarsal artery. NIBP was measured using cuffs of appropriate size placed on the cannon bones or on the tail in random order to detect SAP, MAP, DAP and HR. Results: Sentinel yielded generally higher measurements than Cardiocap. Accuracy of Sentinel was found to vary with recumbency and position of the cuff. No significant difference between Cardiocap and Sentinel due to weight of the horse or acepromazine premedication was found. Conclusion and clinical relevance: Despite a higher variability of Sentinel compared to Cardiocap, NIBP measurements are an appropriate alternative to measure blood pressure under field conditions

A study of measurement of noninvasive blood pressure with the oscillometric device, sentinel,in isoflurane-anaesthetized horses

Objective: To assess accuracy of noninvasive blood pressure (NIBP) measured by oscillometric device Sentinel compared to invasive blood pressure (IBP) in anaesthetized horses undergoing surgery. To assess if differences between the NIBP measured by the Sentinel and IBP are associated with recumbency, cuff placement, weight of the horse or acepromazine premedication and to describe usefulness of the Sentinel. Study design: Prospective study examining replicates of simultaneous NIBP and IBP measurements. Animals: Twenty-nine horses. Methods: Invasive blood pressure was measured via a catheter in the facial artery, transverse facial artery or metatarsal artery. NIBP was measured using appropriate size cuffs placed on one of two metacarpal or metatarsal bones or the tail in random order. With both techniques systolic (SAP), mean (MAP), and diastolic (DAP) arterial blood pressures and heart rates (HR) were recorded. A mixed effects model compared the IBP to the NIBP values and assessed potential effects of catheter placement, localisation of the cuffs in combination with recumbency, weight of the horse or acepromazine premedication. Results: Noninvasive blood pressure yielded higher measurements than IBP. Agreement varied with recumbency and cuff position. Estimated mean differences between the two methods decreased from SAP (lateral recumbency: range −5.3 to −56.0 mmHg; dorsal recumbency: range 0.8 to −20.7 mmHg), to MAP (lateral recumbency: range −1.8 to −19.0 mmHg; dorsal recumbency: range 13.9 to −16.4 mmHg) to DAP (lateral recumbency: range 0.5 to −6.6 mmHg; dorsal recumbency: range 21.0 to −15.5 mmHg). NIBP measurement was approximately two times more variable than IBP measurement. No significant difference between IBP and NIBP due to horse's weight or acepromazine premedication was found. In 227 of 1047 (21.7%) measurements the Sentinel did not deliver a result. Conclusion and clinical relevance: According to the high variability of NIBP compared to IBP, NIBP measurements as measured by the Sentinel in the manner described here are not considered as an appropriate alternative to IBP to measure blood pressure in anaesthetized horses