Today we’re talking all about how to get the most accurate blood pressure readings in practice. As we all know, blood pressure monitoring features heavily in our role as veterinary nurses, but obtaining an accurate result can be a real challenge - especially in our very stressed patients (cats!), in smaller patients, and in patients with certain medical conditions.

If you want to make sure you’re getting the most accurate blood pressure results in your patients, keep reading to find out my top tips, and access the free download that accompanies this post!

Method

The first thing to think about when measuring blood pressure is which method you want to use. Are you going to use Doppler or oscillometric techniques for your patient? As a general rule, Doppler is preferred in very small patients, conscious (mobile!) patients, and patients with cardiac arrhythmias, hypotension or hypovolaemia where detecting a peripheral pulse may be challenging. Where Doppler is used, headphones must be worn, particularly when performing blood pressure measurement in cats, as the noise can be startling and contribute to stress (and therefore hypertension!)

Environment

We need to consider the impact of a patient’s environment on their blood pressure. ‘White coat hypertension’ is commonly seen in stressed patients, particularly cats; this can make accurately diagnosing hypertension a real challenge.

Where are you going to perform your BP measurement? Is your patient in a consulting room - and if so, how long have they been there? Have they had any acclimatisation time? Do they prefer being in their kennel, or is performing a measurement in their kennel likely to cause stress?

Think about which environments the patient is calmest in, and take time to prepare the patient’s environment ahead of the blood pressure measurement. Using pheromones in the environment such as Feliway or Adaptil can be very helpful in reducing stress; additionally, having comfortable bedding on the floor or table, or leaving cats in the bottom half of their cat carriers, can help patients relax in the consulting or treatment area, minimising the effect of stress on blood pressure.

We also want to make sure that the patient’s environment is kept consistent at each blood pressure measurement - so make sure you note where the measurement took place, ready for next time.

Site

There are several sites which can be used for blood pressure measurement, including the tail, the palmar aspect of the forelimbs above the main pad, the plantar aspect of the hindlimb above the main pad, and the dorsal aspect of the hindlimb, over the medial metatarsals. An appropriate site should be selected for the individual patient (do they hate their feet being touched? do they have an injury to any specific limb?) and this used for each reading.

During blood pressure measurement, the site should be kept as level with the heart as possible, whilst minimising any stress to the patient - for example, if you are using the forelimb, hold this level with the heart during measurement, and avoid letting the patient stand with that leg on the floor.

Cuff

Size

Ensuring the blood pressure cuff is an appropriate size is another important factor in maximising accurate results. Use a cuff that is too small, and you’ll get a falsely high reading; use a cuff that’s too large, and you’ll get a falsely low reading.

Measuring your cuff is the best way to ensure it’s the correct size. To do this, turn the cuff vertically and wrap the short end of the cuff around the patient’s limb. The width of the cuff should be around 40% of the limb circumference. Too long, and it’s too large; too short, and it’s too small.

Position

Each blood pressure cuff has an optimal zone which should be placed over the artery. This is usually marked on the cuff itself, either with an arrow, a marker saying ‘artery’, or a shaded zone. If your blood pressure cuff does not have a marker, the area of the cuff where the tubing attaches should be aligned over the artery, to get the most reliable result.

Number of Readings

When measuring blood pressure, a sufficient number of readings should be taken at each measurement, and an average result calculated. Generally, around 3-5 consistent readings should be collected in order to generate an average; if any readings are significantly different to the others, these should be discarded and a new reading performed.

When using the oscillometric or HDO method, a heart rate measurement should also be performed. If the heart rate generated by the blood pressure monitor does not match the one you’ve counted with your stethoscope, the reading is considered inaccurate and should be discarded.

Record Keeping

Record keeping is a vital part of blood pressure measurement; this ensures that any follow-up measurements are performed consistently, and that their readings are as reliable as possible. The veterinary team should record several things when performing blood pressure measurement, including:

Patient details
Method used
Environmental details
Staff members present
Patient temperament during measurement
Cuff site
Cuff size
Each individual result
The overall average result

To make recording all of your blood pressure measurement information even easier, I’ve created a blood pressure monitoring form for you to download and use in practice! Simply enter your email address in the box below, and it’ll be sent straight to you (don’t forget to check your junk folder!)

So as we’ve discussed, there are a number of different factors which can affect our ability to get an accurate blood pressure reading; by selecting an appropriate blood pressure measurement method, cuff size and measurement site, as well as ensuring our patients stay calm throughout, we can ensure our results are as accurate as possible, whilst keeping us and our patients happy!

Don’t forget to grab your FREE blood pressure monitoring form, and happy measuring!

References:

Aldridge, P. and O’Dwyer, L. (2013) Practical Emergency and Critical Care Veterinary Nursing. Chichester: Wiley-Blackwell.
Kirby, R. and Linklater, A. eds. (2017). Monitoring and Intervention for the Critically Ill Small Animal – The Rule of 20. Iowa: Wiley-Blackwell.
Merrill, L. ed. (2012). Small Animal Internal Medicine for Veterinary Technicians and Nurses. Iowa: Wiley-Blackwell.
Sierra, L. and Savino, E. 2015. Blood Pressure Monitoring From a Nursing Perspective, Part 2: Blood Pressure Monitoring Techniques. Today’s Technician [Online] Available from https://todaysveterinarypractice.com/todays-technician-blood-pressure-monitoring-from-a-nursing-perspective-part-2-blood-pressure-monitoring-techniques/

How to get the most accurate blood pressure readings in practice