ISSN 2398-2942      

Blood pressure: direct measurement

icanis
Contributor(s):

John Dodam

Synonym(s): Invasive arterial blood pressure monitoring


Introduction

Rationale

  • Arterial blood pressure is the product of stroke volume, heart rate and total peripheral resistance.
  • There is some variation between published values for 'normal' arterial blood pressure in different sources. Suggested values: systolic pressure 105-145 mmHg; diastolic pressure 55-85 mmHg; mean arterial pressure 90-110 mmHg.
    Mean pressure is the hydrostatic intravascular pressure in the vessel during one complete cardiac cycle, NOT the arithmetic mean of the systolic and diastolic pressures
  • Almost all general anesthetic drugs and some premedicant drugs cause hypotension by affecting one or more of the following factors: total peripheral resistance, stroke volume, heart rate. Their effects are often dose related.
  • Adequate arterial blood pressure is necessary to maintain sufficient tissue perfusion to avoid cellular damage and/or death.
  • In anesthetic monitoring, mean arterial pressure should be maintained above 70 mmHg.

Uses

  • Accurate monitoring of arterial blood pressure enables appropriate corrective measures to be taken to ensure adequate tissue perfusion if hypotension develops.
  • Particularly beneficial in animals which are hypovolemic prior to surgery, have pre-existing cardiovascular system disease, or are undergoing procedures where significant blood loss or large fluctuations in blood pressure are anticipated.
  • Mean arterial pressure and cardiac output are maintained at normal levels until 10% of circulating blood volume has been lost.
  • Mean arterial blood pressure is maintained by constriction of arterioles at deficits of circulating blood volume between 10 and 20%, but cardiac output is reduced.
  • At deficits of circulating blood volume in excess of 20%, mean arterial blood pressure is no longer maintained and hypotension develops.

Pros

  • Most accurate estimation of arterial blood pressure.
  • Equipment required for determination of mean arterial pressure alone is inexpensive compared with that for oscillometric indirect technique.
  • Arterial cannulae can also be used to collect samples for blood gas analysis.

Cons

  • Requires arterial cannulation with attendant risks, eg hemorrhage, sepsis, thromboembolism.
  • Arterial cannulation technique requires practice.
    Gain practice on a peripheral artery in medium to large breeds after anesthesia has been induced, eg dorsal pedal (metatarsal) artery. Pressure dressing can be used to control any hemorrhage/hematoma formation more easily than in larger, more proximal vessels.
  • Equipment required to display and record systolic, diastolic and mean arterial blood pressure is expensive.

Alternatives - indirect techniques

Preparation

  • Collect all necessary equipment.
  • Prepare selected site aseptically.

Requirements

This article is available in full to registered subscribers

Sign up now to obtain ten tokens to view any ten Vetlexicon articles, images, sounds or videos, or Login

Procedure

This article is available in full to registered subscribers

Sign up now to obtain ten tokens to view any ten Vetlexicon articles, images, sounds or videos, or Login

Further Reading

Publications

Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Bodey A R & Rampling M W (1999) Comparison of haemorrheological parameters and blood pressure in various breeds of dog. JSAP 40 (1), 3-6 PubMed.
  • Bodey A R, Young L E, Bartram D H et al (1994) A comparison of direct and indirect (oscillometric) measurements of arterial blood pressure in anesthetised dogs, using tail and limb cuffs. Res Vet Sci 57 (3), 265-269 PubMed.
  • Kittleson M D & Olivier N B (1983) Measurement of systemic arterial blood pressure. Vet Clin of N Am - Small Anim Pract, 13 (2), 321-336 PubMed.

Can’t find what you’re looking for?

We have an ever growing content library on Vetlexicon so if you ever find we haven't covered something that you need please fill in the form below and let us know!

 
 
 
 

To show you are not a Bot please can you enter the number showing adjacent to this field

 Security code