Hi all
I am also thoroughly enjoying this debate and agree with the discussion regarding the technology and what can be detected. When the RCTs were performed (IA v EFM) lack of ability to detect variability did not seem to be significant and there is no evidence that it can be detected by IA. I am very interested to hear the debate regarding counting strategies as improvement in detection of the different aspects of the auscultated heart rate pattern is the focus of my PhD. I hope to be able to shed more light on this when I complete my research
Best wishes
Julie
Julie Harrison
Senior Lecturer (Midwifery)
Room 81a 2nd Floor Grosvenor Wing,
St Georges University of London
Cranmer Terrace
London SW17 ORE
( 0208 725 2014
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-----Original Message-----
From: A forum for discussion on midwifery and reproductive health research. [mailto:[log in to unmask]] On Behalf Of Devane, Declan
Sent: 21 September 2010 10:37
To: [log in to unmask]
Subject: Re: Intermittent auscultation query
Hi all
Thoroughly enjoyable debate and interesting to see that the issues are the same across many countries.
Our assumptions around the technology ad what it can, or cannot, tell us fascinate me. Like Robyn, I do not believe we should be seeking to determine variability with IA.
I'll give my reasons. When I teach I tend to go into how the technology...some students will undoubtedly say I do so too much....
External fetal heart rate monitoring by ultrasound (by CTG or hand held Doppler (at least any I have seen)) use signal processing techniques, which we know as autocorrelation, which detects the cyclic fetal heart beats and displays the findings of it's processing as a beat. We notice that the value displayed on the CTG or hand held Doppler isn't changing every 0.5 to 1 second. Instead, what is displayed is the value resulting from this signal processing. I like to think of this an 'average' and this is actually quite close to what the processing does. This is why we know that the CTG and the Doppler cannot display beat-to-beat variability but we believe it to be adequate for displaying baseline variability. This helps me in my teaching about the problems of measuring variability and IA with Doppler, which goes something like. The hand held Doppler cannot detect beat-to-beat variability (assuming it uses autocorrelation, which most do). Baseline variability, we know, reflects the pattern of fluctuations of the fetal heart around the baseline over a period of time. Listening for one minute with a hand held Doppler and giving the range or upper and lower limits doesn't tell me baseline variability but the variability around an averaged (because of autocorrelation) fetal heart rate for THAT minute, which might be very different to the 'pattern' of baseline variability. In effect, you would need to be continuously recording and documenting rates with a hand held Doppler to be able to determine baseline variability. No one believe that continuous IA is practical or desirable, so I do not see determination of baseline variability as it currently stands as a good idea for IA with Doppler.
Pinards and other fetoscopes do tell us the actual number of beats at a given time (no autocorrelation here) but the human ear needs time to count them and give an average. Giving a range is susceptible to the same problems with baseline variability above then it could be argued, as with Doppler, that one would need to be counting continuously to see the 'pattern' needed to determine baseline variability.
It strikes me that we focus on baseline variability, which is appealing because it has a real physiological link to autonomic nervous system functioning, because of the importance we attribute to it in CTG monitoring. Yet, taken together we have no high quality evidence of benefit for continuous CTG compared with IA during labour for women WITH or without risk factors with exception of reduction in seizures in women without risk factors. No high quality evidence of benefit for antenatal CTGs either. The cynic in me always wants to ask what is the evidence of benefit of IA too but that's another question.
Best wishes
Declan
Declan Devane
Senior Lecturer
School of Nursing and Midwifery
National University of Ireland Galway
University Road
Galway
Ireland
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-----Original Message-----
From: Deborah Caine [mailto:[log in to unmask]]
Sent: 20 September 2010 23:45
Subject: Re: Intermittent auscultation query
I would be interested to know what tool is being used in IA which epitomises the listening and counting. Where I work we are used to hand held dopplers which certainly don't show a constant rate, and therefore many (but not
all) would record a range (e.g. 147-159). I would have thought that such a range would indicate the presence or absence of variability.
Deborah
Belinda Cox writes:
> Dear Robyn,
>
> Thank you so much for this! I was feeling really uncomfortable about
> the variability, Dr C Bravado and sticky labels issue around IA, but
> hadn't actually managed to think through why. You've done it for me,
> and actually this is what I teach on our fetal monitoring sessions. I
> can't wait to read more from you :-)
>
> Best wishes,
>
> Belinda
>
> Belinda
> -----Original Message-----
> From: A forum for discussion on midwifery and reproductive health research.
> [mailto:[log in to unmask]] On Behalf Of Robyn Maude
> [CCDHB]
> Sent: Monday, September 20, 2010 7:26 AM
> To: [log in to unmask]
> Subject: Re: Intermittent auscultation query
>
> Hi All
>
> I am a midwifery PhD candidate in New Zealand . I am doing my research
> on midwives' practices of fetal monitoring for low risk women, in
> particular intermittent auscultation. We have had some very
> interesting discussions on IA over the last couple of years and it
> seems there is still plenty to discuss. I started a thread on this
> back in 2007 which I have collated for my thesis work - it is very
> interesting looking at feedback from around the globe.
>
> I am doing a multi methods quasi experimental design using pre and
> post intervention assessment of practice - getting a snapshot of
> practice by reading notes and talking to midwives and then delivering
> an education package (the intervention) which incudes history,
> physiology, research and introducing midwives to a model I have
> developed for the conduct, interpretation of IA, this is followed by
> another snapshot of practice and focus groups to see whether there has
> been any change in practice following the intervention. I am looking
> for changes in the number of eligble woman who get IA, the way it is
> conducted i.e. frequency timing and duration and the birth outcomes when IA is used.
>
> My model for practice was presented in an oral presentation and a
> poster at the normal birth conference in Vancouver in July this year
> and provides a framework for the use of IA as an admission assessment
> and for ongoing FHR monitoring.
>
> Part of the work and model is around how we document our FHR
> monitoring using IA that demonstrates it is a robust evidence-based
> FHR modality that is reasurres us that the fetus is well but is alo
> capable of detecting FHR abnormalities so that the appropriate actions
> are taken - this is all it needs to do. The model and the
> documentation demonstrate critical thinking and the decision-making trail.
>
>
> Applying what we know about EFM is not useful. IA is a listening and
> counting method, factors such as variability are notions from EFM.
> Timing freqency and duration are set out in the guidelines are drawn
> from the protocols used RCTs comparing IA and EFM - so whilst they
> have not been subjected to robust testing they are at this pointin
> time the only protocols we have to guide practice that have been used
> in research. Looking at many guidelines they tend to have a range
> 15-30 mins in active labour - but this is a whole further discussion
>
> I think how we talk about and document IA findings needs to be done
> carefully so we are not trying to emulate EFM. Therefore we talk about
> FHR increases (from a baseline previously determined) and FHR
> decreases which are not defined further (because they can't be with this method).
> I feel very strongly that we do not record the auscultated FHR as a
> range, which midwives believes shows variability (a notion from EFM)
> IA is a listening and counting method - we dont write a woman's pulse
> rate as a range! The FHR is auscultated after a contraction as tis is
> when we are more likely to hear a decrease if one is present. FHR
> decreases after a contraction are more problematic than those heard
> during a contraction, hence the timing. Arulkumaran has discussed
> multiple count methods - which I agree are very hard to do and
> commented on the fact that they can amplify the inaccuracy of the
> finding because of the difficulty.
>
> A comment on the use of Dr C BRAVADO and sticky labels emulating EFM
> characteristics - I have a real uncomfortable feeling about using
> these as I do not think they demonstrate IA/Normality/Low risk well
> enough and add to the confusion midwives experience when they attampt
> to use EFM tools to interpret IA. Feistein, Sprague and Trepanier,
> 2008 (AWHONN) have produced a good flow chart for IA recording. I have
> sought permission to adapt this flow chart as part of my PhD work as I
> think we need to incorporate other things that demonstrate maternal
> and fetal wellbeing.
>
> I am loving these discussions because it highlights again the need to
> research this method of fetal surveillance to get some credibilty for
> it and to introduce or reintroduce it back into practice.
>
> Look forward to more discussions
>
> Cheers, Robyn Maude
> [log in to unmask]
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