Agreement of invasive and non-invasive blood pressure measurements in anaesthetised pigs using the Surgivet V9203

The automated oscillometric method is a common method for measuring blood pressure non-invasively and is broadly and confidently used in the veterinary setting. Twenty-one pigs undergoing anesthesia for exploratory laparotomy were enrolled in a study to evaluate the performance of the Surgivet V9203 non-invasive blood pressure (NIBP) monitor. The aim was to compare measurements of arterial blood pressure obtained simultaneously using the Surgivet V9203 oscillometric system and an infra-arterial catheter-transducer system, both at the level of the metatarsus. Invasive blood pressure (IBP) was consistently underestimated by the non-invasive method. Bland-Altman analysis showed poor agreement between the two modalities based on evaluation of mean bias and 95% limits of agreement. The Surgivet V9203 cannot therefore be recommended as a reliable alternative to invasive blood pressure monitoring in anaesthetised pigs. As pulse detection is one of the most important factors affecting NIBP accuracy it is likely that our findings may reflect an anatomical or physiological difference in the species that alters the detection of wall movement by the oscillometric technique and additionally, makes the algorithm used by the Surgivet to determine blood pressure parameters unsuitable for use in pigs.