Study of arterial blood pressure in newborn foals using an electronic sphygmomanometer

Abstract

Summary An electronic sphygmomanometer which functions on oscillometric principles, was used to measure arterial blood pressure in foals. Its accuracy was assessed by comparison with results obtained by direct measurement in anaesthetised pony foals, aged 34 to 64 days. Correlations between data obtained by the two methods were highly significant but the sphygmomanometric readings were consistently lower than those obtained by direct measurement. An equation was derived from the pooled values for mean, systolic and diastolic pressure measurements. This was used as a correction factor when the oscillometric method was employed in the field on Thoroughbred foals, during the first three days post partum, and on pony foals during the first day only. There were no significant differences between systolic, diastolic and mean values in Thoroughbreds on Days 1, 2 or 3 after birth. Measurements recorded on the first day after foaling were significantly lower (P<0.025) in ponies than in Thoroughbreds. Blood pressure measurements in Thoroughbreds and ponies were substantially higher than those reported previously using the ultrasonic Doppler technique.

Equivalence between invasive and oscillometric blood pressures at different anatomic locations in healthy normotensive anaesthetised horses

“…The NIBP technique at the MC and RU consistently underestimated IBP. This is consistent with assessment of NIBP in foals in which measurements over the median artery were consistently lower than with the invasive MAP [23]. The inaccurate results of NIBP at the MC agree with a study assessing NIBP measurements at the metacarpus in camelids, which found marked differences between invasive and noninvasive measurements [24].…”

Technical and methodological requirements for reliable haemodynamic measurements in the unsedated calf

“…For instance, non-invasive systemic arterial pressure measurements are known to generate lower values than invasive measurements in animals (Franco et al, 1986). The site of the pressure measurements is also a factor which should be considered, because pressure values at any point above or under the heart level are influenced by a hydrostatic effect (Detweiler, 1984).…”

Sedation and general anaesthesia of the foal

“…If indirect techniques such as ultrasonic Doppler recording or electronic sphygmomanometry are used, calculated MAP may be as low as 50 mmHg in normal one-day-old foals, rising to 60 to 70 mmHg at age 2-3 weeks (Lombard et al 1984). Regardless of the technique used, pony foals (Lombard et al 1984) have a slightly lower arterial blood pressure than Thoroughbred foals (Franco et al 1986). Direct measurement of MAP via an arterial catheter reveals consistently higher values (Franco et al 1986), but a steady increase in blood pressure with age is still apparent.…”