Abstract

Measurement of arterial blood pressure (ABP) is an essential part of anesthetic monitoring in human and domestic animal anesthesia,¹ but this modality is rarely used with reptilian patients². Invasive blood pressure monitoring (IBP) using an intra-arterial catheter and arterial blood pressure transducer is considered the gold standard, but this methodology is labor intensive and somewhat risky as surgical placement of the catheter is typically required.^1,3 Our goal was to validate a non-invasive oscillometric blood pressure (NIBP) monitor (Cardell Veterinary Model 9401) for use in medium to large boid snakes.

An intra-arterial catheter was placed in the right aortic arch and connected to a pressure transducer and oscilloscope to determine direct systolic, diastolic and mean arterial blood pressure.⁴ A blood pressure cuff measuring 40% of the circumference of the tail was placed distal to the vent. Simultaneous readings of IBP and NIBP were taken over a 45-min period for each animal.

At the time of abstract preparation, final data were available for three adult boa constrictors (Boa constrictor). Oscillometric blood pressure readings tended to underestimate diastolic and mean arterial blood pressure (MAP) and overestimate systolic arterial pressure. The difference between NIBP MAP and IBP MAP was smallest in the range of 50–60 mm Hg. These findings are similar to those found in domestic small animals when comparing invasive and non-invasive blood pressure monitoring.^5,6 Further study is warranted to determine accuracy of NIBP in snakes of varying body sizes and the effects of short-term and prolonged hypotension in snakes.

Literature Cited

1.  Mazzaferro, E., and A.E. Wagner. 2001. Hypotension during anesthesia in dogs and cats: recognition, causes, and treatment. Compend. Contin. Educ. Pract. Vet. 23(8):728–738.

2.  Read, MR. 2004. Evaluation of the use of anesthesia and analgesia in reptiles. J. Am. Vet. Med. Assoc. 224(4):547–552.

3.  Burrows, C.F. 1973. Techniques and complications of intravenous and intra-arterial catheterization in dogs and cats. J. Am. Vet. Med. Assoc. 163:1357–1363.

4.  Wang T., J. Altimiras, and M. Axelsson. 2002. Intracardiac flow separation in an in situ perfused heart from Burmese python (Python molurus). J. Exp. Biol. 205(17):2715–2723.

5.  Meurs, K.M., M.W. Miller, and M.R. Slater. 1996. Comparison of the indirect oscillometric and direct arterial methods for blood pressure measurements in anesthetized dogs. J. Am. Anim. Hosp. Assoc. 32(6):471–475.

6.  Sawyer, D., A.H. Guiken, and E.M. Sigel. 2004. Evaluation of a new oscillometric blood-pressure monitor in isoflurane anesthetized dogs. Vet. Anaesth. Analg. 31:27–39.