Comparison of Thames Medical CAT+ Doppler and AutoCAT+ Automatic Blood Pressure Monitor devices for non-invasive blood pressure measurement in cats

ObjectivesA comparative assessment of systolic blood pressure (SBP) measurement was carried out for anaesthetised and conscious cats by using two non-invasive approaches based on the Doppler method and a newly developed oscillometric instrument.MethodsSBP was recorded on 131 occasions in 26 cats entering a shelter environment. Six of these cats were monitored while under a general anaesthetic for elective procedures and the rest were conscious during routine health assessment. A paired approach was followed using the Doppler method followed immediately by the oscillometric approach. Mean values and coefficient of variations were calculated. A normal distribution was confirmed before a standard Bland-Altman analysis was completed.ResultsThe mean SBP (±SD) for the 131 paired readings was 113.3 ± 23.9 mmHg and 116.3 ± 26.7 mmHg for the Doppler and oscillometric methods, respectively. The small difference in means was not significant. Anaesthetised cats had significantly lower SBP values than those that were conscious. The data set for 16 cats with three replicated paired measurements and a subset of 12 with five such replicated measurements also provided similar normally distributed mean values and a high correlation coefficient. The Bland-Altman plot suggested a positive bias of the oscillometric approach of +3.07 ± 12.3 mmHg (limits of agreement of -21.0 to 27.1 mmHg) and +4.93 ± 9.38 mmHg (limits of agreement of -13.5 to 23.3 mmHg) for the 16- and 12-cat subgroups, respectively. There was 100% agreement between the two methods in allocation to a hypertension class.Conclusions and relevanceThe results establish that the new AutoCAT+ instrument met some of the guidelines for assessing such instruments for veterinary use with cats with a normal range of blood pressure. Further work is needed with a larger data set spanning hypotension to hypertension for complete validation.