Developing new guidance on how to measure lying and standing blood pressure - harder than you think!
Shelagh O’Riordan is a consultant geriatrician and the clinical lead for the National Audit of Inpatient Falls. She was an acute hospital geriatrician in Canterbury in Kent for 14 years but moved in September 2016 to work Kent Community Foundation Trust as a community geriatrician. She developed and runs East Kent Falls and Osteoporosis service. She tweets at @jupiterhouse1
As the clinical lead for the National Audit of Inpatient Falls (NAIF) I have been involved in the development of some new tools to standardise fall prevention in hospitals and they are being launched this month. The first of these was launched on 13/01/17 and is on the measurement of lying and standing blood pressure.
One of the results we found in the last audit round (data collected May 2015) was that on average only 16 per cent of patients over 65 years in an acute hospital after 48 hours had had a lying and standing BP recorded! I found this to be a fairly shockingly low number. I’m known, like many geriatricians, to be a bit obsessed with measuring lying and standing BP. The reasons for this are that a drop in BP on standing is so common in acutely ill older people in hospital and it is readily amenable to simple changes (unlike many other causes for falls in hospital). This drop in BP is commoner in hospital as the patient may be fluid depleted due to sepsis, unable to reach drinks or due to a delirium causing the patient to be unable to understand the need for drinking. Common solutions would be to encourage oral hydration, use of IV fluids or stopping BP medication until it resolves.
I have a team of clinicians who help me with NAIF and we asked ourselves the question- why do we not measure lying and standing BP in hospital? It doesn’t take long, it can be part of any session when the patient is being encouraged to mobilise and to me, it seems to give useful results! The more I talked to nursing, therapy and medical staff, the clearer it became that there was definitely a problem with knowing how best to measure it. One therapist told me she had given up measuring it as all the consultant geriatricians on her wards had different ideas of how to measure and what was significant. She told me one consultant insisted the patient be lying for at least 30 minutes before taking the first measurement and then measure every minute for 10 minutes!
This led us to try find out what was current practice across clinicians involved in falls prevention in hospitals. We sent out a survey monkey questionnaire to all the email databases we could reasonably commandeer and got 316 responses. The majority of responses came from nurses, medics and therapists. I’m pleased to say that although there was a wide variation in the answers on how to measure, the majority of clinicians were using what seemed to me and my clinical colleagues at NAIF to be a common sense approach that matched published guidance. Essentially this led us to recommend lying for at least 5 minutes, taking the first BP and then standing to measure in the first minute and at 3 minutes. After reviewing the responses and current recommendations we stuck to the usual advise of what was a positive result (drop of >20 mmHG for systolic and >10 with symptoms for diastolic or to a systolic BP <90mmHg on standing). Personally I am much less interested in the diastolic BP drop as clinically I find it really doesn’t fit with clinical symptoms but I was over ruled by the team and it stayed as a recommendation!
The question of which type of sphygmomanometer to use proved to be a tricky one. All guidelines say to use a manual machine. Many of us will have experienced the irritation when using an automatic sphyg which shows the error message on standing, particularly in patients who need to hold onto a frame to stand. However, our survey showed that two thirds* used an automatic machine despite this advice. It seemed to me that there was no point issuing guidance everyone will ignore so we ended up with another pragmatic sentence along the line of “use a manual machine if you’ve got one and definitely if the automatic machine fails to record”. I know the purists amongst us will sigh and say we are watering down evidence based advice but I wonder, how many clinicians are not measuring lying and standing BP because there isn’t a manual machine available? Surely measuring with an automatic machine is better than not measuring at all?
At the end of the day, all we have done is issue pragmatic user friendly advice on how to measure lying and standing BP for staff to use on the wards. It comes with the RCP logo, for what that is worth, and hopefully will allow staff to challenge instructions to measure in different ways from their seniors who may have different views. Will this lead to more people measuring lying and standing BP in hospital? I hope so but it’s never going to be the only answer. Really understanding why a test is needed and seeing the difference it makes when interventions are successful is essential and takes a change in culture on our wards. The advice is available on the RCP website and you can request a pack of lanyard cards to distribute on your wards.
*47.8% reported using an automatic machine and 18.2% reported using an automatic or manual machine Ie only 33.3% reported using only a manual machine.