Tools of the trade: Parks Doppler Flow Detector 811-B

Doppler flow detector

by Dr Cale Weston, Nairne Vet, SA

This doppler unit is at least five years old but still works well. We use it every day for indirect blood pressure monitoring. Newer models might look a bit fancier, but the technology is essentially the same. We have no plans to update it.

What’s good about it

Hypertension is so common during anaesthesia, it’s critical that we identify the condition and adjust our anaesthetic and fluid rates accordingly. It’s imperative the blood pressure stays stable and above the lower limit we deem safe. The Flow Detector is a reliable way to indirectly monitor the systolic blood pressure while also producing an audible heartbeat. A probe is placed on the vasculature of the distal limb. A small patch of fur needs to be clipped in order to have direct contact. I also use conduction gel and then tape the probe in place. Once it’s positioned properly, the pulse becomes audible. Hearing the heartbeat at a steady rate allows us to quickly identify any changes. A cuff is then placed closer to the animal’s chest. Inflating the cuff until you can no longer hear the pulse gives the approximate systolic blood pressure. While it’s a very easy way to monitor, it requires a bit of manual labour when setting up. This unit is more reliable than some expensive oscillometric blood-pressure monitors with automatic cuff inflators.

What’s not so good

It’s a fiddly process that can be quite tricky on very small animals. While it’s just an indirect blood-pressure monitor, realistically there are very few places that are using direct blood-pressure monitoring.

Where did you get it

Specialised Australian Veterinary Equipment


  1. From above: Hypertension is so common during anaesthesia, … stable and above the lower limit we deem safe. Shouldn’t this concern be about Hypotension vs Hypertension?


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