VERY LONG
Dear Colleagues
Back in the '90s, I was struck by this topic of maternal IV fluids during
parturition. It was the first time I had seen a woman receive an epidural,
and she was bolused 500-1000 of normal saline over a few minutes (to prevent
her blood pressure from dropping). I was really struck by this strategy
because I am a dialysis patient - I have not voided for a couple of decades
- so fluid means a lot to me. I was also aware of fetal physiology and how
the opportunity is there for fetuses to pick up fluid (passive diffusion -
electrolytes [and therefore fluid] move from an area of high concentration
to areas of low concentration).
As a LLL Canada Leader and a home visit nurse, I was very aware of how
babies varied in weight loss despite the fact they all get "vapours" and how
this weight loss worries mothers. Later, as a nurse in a hospital, I saw
how often the topic of infant weight loss was discussed - "how could this
little guy have dropped so much? The scale must be wrong. He is alert and
going to his mom's breast just fine..." Maternity nurses who had worked
other areas (eg., dialysis, cardiac) questioned the calvalier use of fluids
- patients in other areas would likely have experience pulmonary edema or
heart failure due to the overuse of fluid.
My doctoral thesis is on this topic. It is titled "Demographic,
Physiological, and Iatrogenic Factors Affecting Neonatal Weight Loss".
Among the variables I am following, I want to see if I can pick up an
association between the maternal IV fluids and neonatal weight loss. I am
about halfway through my data collection. My methods are very similar to
the ones used by Lamp and Macke in their article 2010 JOGNN article,
Relationships Among Intrapartum Maternal Fluid Intake, Birth Type, Neonatal
Output, and Neonatal Weight Loss During the First 48 Hours After Birth
[JOGNN, 39, 169-177; 2010. DOI: 10.1111/j.1552-6909.2010.01106.x]
Battaglia et al (1960) were probably the first to show that maternal IV
fluids affect the neonate. Others also showed the relationship, as did
Dahlenburg et al - cord blood was hyponatrermic (low sodium - in other words
diluted). As an IBCLC, I want to take this concept one step further and see
what the effect is for breastfed babies. The work is complex because
feeding factors, demographics, other medications etc can all affect infants
weight loss. These studies support my hypotheses and when I began there had
been no conclusive evidence that there was an association between maternal
fluids and neonatal weight loss.
Something else has come up about neonatal physiological weight loss. As I
wrote up the research proposal, I need a sentence or two about what a normal
physiological weight loss is for neonates - 10% had been common to say, but
the current clinical practice guidelines (I used ABM, AAP, RNAO, ILCA)
stipulate 7% as the red flag. I completed and published a systematic review
to look at neonatal weight loss patterns - wow !! what an eye opener that
was.
I found references to 7% in two places. First, it seems to be a mean (in
other words the statistical halfway mark). To say 7% is a problem is to say
half of the babies are compromised. The other place I found it was in a
secondary analysis of data, and the authors found that weight loss exceeded
7% in only 8.7% of infants. This study from 1991 was the earliest reference
I could find to the 7% loss. The babies in the study were weighed twice in
two weeks around day 5 and day 10. Based on this data, the conclusion was
babies should not lose past 7%? The nadir (lowest point) is around day 3
and with so few measurements, how can one assume the lowest weight was even
measured.
The other eye opener with doing this systematic review was the poor quality
of "evidence" used to support conclusions about weight loss. Studies are
cited that are not primary research, papers were referenced that have no
reference at all, and presentations were cited even though the speaker was
not presenting primary reserach.
Assuming a normal curve, the 7% with SD of 2 suggests 95% of babies will
fall between 3 and 11%. The biggest problem with my systematic review is
that it does not related weight loss to morbidity and mortality -
essentially it shows a pattern but does not answer the so what...
The systematic review is available online from Open Medicine -
http://www.openmedicine.ca/issue/view/9
The other thing I came to realize is that we assume birth weight (the first
weight within minutes of birth) should be baseline. Why? In dialysis,
there is something called "dry weight" (I cannot find it in any other area),
and dry weight is the goal weight (weight without extra fluid) for each
dialysis. What if the theory is right and babies are over in their fluids?
The weight loss is a correction - getting back to dry weight. Baseline
should not be the first weight. Baseline should be following diuresis. In
other words, there is an assumption that all weight loss is due to lack of
food, and everyone has set this false baseline as the goal to get back to.
At this point, there is no clear evidence of an association between neonatal
weight loss and maternal IV fluids, but we are closer to showing that there
are non feeding factors related to weight loss and that there may be weight
loss that is a correction not cause for concern.
Joy
__________________________________________
Joy Noel-Weiss RN IBCLC PhD(c)
Newborn Weight Loss Study
École des sciences infirmières/School of Nursing
University of Ottawa/Université d'Ottawa
451 Smyth RGN3249C
Ottawa ON Canada K1H 8M5
Tél./Tel. 1-613-228-9529
Fax/Télécop. : 1-613-562-5443
Courriel: [log in to unmask]
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