There are a number of groups that measures intraoral pressures and all
did it differently, different diameter tubes, different places in the
mouth, different containers between the pressure valve and the tube,
even in the same units, different results.
Holly McClellan in Peter/Donna's lab got the highest numbers, she was
studying babies who hurt mom's nipple and found they had excessively
high vacuums. Prieto, Zhang, others have measured lower negative
pressures than Donna, but only slightly lower. Jimmie Francis measured
intraoral pressures in the anterior mouth and found they were positive,
as did another group who measured them along the cheek, can't pull them
out of my brain right now - but they found positive p in the front of
the mouth, less negative in the middle, and high negative in the back of
the mouth. So a lot seems to depend on how one measures and where.
Hyton's work was back in the 50's, but David Elad thinks the methodology
was sound. I think that the word limits in journals make is sometimes
difficult to replicate and understand the exact methodology of studies.
I love to hear the researcher talk about the study, you learn much more.
Most will answer emails with intelligent questions also.
Hope this helps!
Cathy
Catherine Watson Genna BS, IBCLC NYC www.cwgenna.com
On 11/2/2017 7:18 AM, Margaret Sabo Wills wrote:
> Another possible cause of confusion is that vacuum can be measured with different units -- just as the same distance could be stated in miles or kilometers (or inches and centimeters). Someone who knows the details can actually explain how to convert one to the other so you can compare the various research findings.
> http://www.hydraulicspneumatics.com/200/TechZone/Vacuum/Article/False/6460/TechZone-Vacuum
>
> I remember a speaker (Catherine Watson Genna?) discussing that in the early days, newborns seem to be experimenting more with the suction -- ranging wider -- and then settling down to using just enough pressure within a narrower range. Little scientists! Although I guess there would also be a shift in the baby's approach as the milk volume picks up.
>
> I'm curious how a baby's suction is being measured-- at a soft breast or on a firm device like a pacifier? It seems that those would elicit very different actions from the baby. Wouldn't the suction drop as milk starts flowing into the space? When encouraging mothers to help the baby whomp in a big mouthful of breast, I explain that the more we fill the space, the easier it will be for the baby to create suction.
>
> Good luck with your work.
>
> Margaret Wills, IBCLC
>
>
>
>> Date: Wed, 1 Nov 2017 22:53:25 +0100
>> From: Kika Baeza <[log in to unmask]>
>> Subject: Intraoral negative pressure during suck
>>
>> Hi!!
>>
>> A question... Going through some old presentations, I had written back in
>> 2004 that peak intraoral negative pressure during breastfeeding could reach
>> -240 mmHg. I have no idea right now where I got that information. According
>> to Geddes (2008 and 2012), peak negative pressure is either -122 or -145.
>> Elad and cols, in their 2014 US study using a model, say it ranges from -20
>> to -40.
>>
>> I don´t have Cathy Genna´s Sucking Skills book here at home so I can´t look
>> it up...
>>
>> Any light to shed, anyone?
>>
>> Thanks!
>> KIka
>>
>>
>> --
>> Dra. Carmela Baeza
>> Médico de Familia
>> Consultora Certificada en Lactancia Materna IBCLC
>> www.centroraices.com
>> http://www.facebook.com/Consulta.Lactancia.Raices
>> <http://www.facebook.com/pages/Centro-de-Atenci%C3%B3n-a-la-Familia-Ra%C3%ADces/274415189309122>
>>
>> Autora de "Amar con los Brazos Abiertos"
>> http://www.ediciones-encuentro.es/libro/amar-con-los-brazos-abiertos.html
>>
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