Hypoglycemia has been a frequent topic of posts over the last few years. Specifically, the use of dextrose gels to avoid admission for hypoglycemia and evidence that such a strategy in not associated with adverse outcomes in childhood. What we know is that dextrose gels work and for those centres that have embraced this strategy a reduction in IV treatment with dextrose has been noted as well.
Dextrose gels however in the trials were designed to test the hypothesis that use of 0.5 mL/kg of 40% dextrose gel would be an effective strategy for managing hypoglycemia. In the Sugar Babies trial the dextrose gel was custom made and in so doing an element of quality control was made possible.
In Canada we have had access to a couple products for use in the newborn; instaglucose and dex4. Both products are listed as being a 40% dextrose gel but since they are not made in house so to speak it leaves open the question of how consistent the product is. Researchers in British Columbia sought to examine how consistent the gels were in overall content and throughout the gel in the tube. The paper by A. Solimano et al is entitled Dextrose gels for neonatal transitional hypoglycemia: What are we giving our babies? As an aside, the lead author Alfonso was just announced as the 2019 recipient of the Canadian Pediatric Society Distinguished Neonatologist award so I couldn’t see a better time to provide some thoughts on this paper!
What did they find?
The study examined three tubes each of instaglucose and dex4. For each tube the researchers sampled dextrose gel from the top, middle and bottom and then the dextrose content per gram of gel determined as well as gel density. Glucose concentrations were analyzed high-pressure liquid chromatography tandem mass spectrometry (HPLC-MS/MS) and gas chromatography mass spectrometry (GCMS) were used to determine glucose concentrations and identify other carbohydrates, respectively. In terms of consistency the gels were found to be quite variable with dextrose content that for instaglucose could be as much as 81% and 43% different for dex4. Differences also existed between the different sections of the tubes so depending on the whether it was a fresh tube you were using or not the amount of dextrose could vary.
The authors also discovered that while dex4 contained almost exclusively dextrose, instaglucose contained other carbohydrates not listed on the manufacturer’s ingredient list.
What does it all mean?
The differences are interesting for sure. If the glucose gels are not consistent though should we stop using them? I think the answer to that at least for me is no. Although the data is unpublished, our own centres experience has been that admissions for hypoglycemia have indeed fallen since the introduction of dextrose gel usage (we use instaglucose). What I can only surmise is that in some cases patients may be getting 40% but perhaps in others they are getting as little as 20% or as much as 60% (I don’t know exactly what the range would be but just using this as an example). In some cases of “gel failure” perhaps it is for some babies, receipt of low dextrose containing gel that is at fault or it may be they just have high glucose requirements that gel is not enough to overcome. Other infants who respond quickly to glucose gel may be getting a large dose of dextrose in comparison. Overall though, it still seems to be effective.
What I take from this study is certainly that there is variation in the commercially prepared product. Producing the gel in the hospital pharmacy might allow for better quality control and would seem to be something worth pursuing.
Look around an NICU and you will see many infants living in incubators. All will eventually graduate to a bassinet or crib but the question always is when should that happen? The decision is usually left to nursing but I find myself often asking if a baby can be taken out. My motivation is fairly simple. Parents can more easily see and interact with their baby when they are out of the incubator. Removing the sense of “don’t touch” that exists for babies in the incubators might have the psychological benefit of encouraging more breastfeeding and kangaroo care. Both good things.
Making the leap
For ELBW and VLBW infants humidity is required then of course they need this climate controlled environment. Typically once this is no longer needed units will generally try infants out of the incubator when the temperature in the “house” is reduced to 28 degrees. Still though, it is not uncommon to hear that an infant is “too small”. Where is the threshold though that defines being too small? Past research studies have looked at two points of 1600 vs 1800g for the smallest of infants. One of these studies was a Cochrane review by New K, Flenady V, Davies MW. Transfer of preterm infants for incubator to open cot at lower versus higher body weight. Cochrane Database Syst Rev 2011;(9). This concluded that early transition was safe for former ELBWs at the 1600g weight cut off.
Infants in this gestational age range with a birth weight <1600g were randomly assigned to a weaning weight of 1600 or 1800 g. Within 60 to 100 g of weaning weight, the incubator temperature was decreased by 1.0°C to 1.5°C every 24 hours until 28.0°C. Weaning to the crib occurred when axillary temperatures were maintained 36.5°C to 37.4°C for 8 to 12 hours. Clothing and bedcoverings were standardized. The primary outcome was LOS from birth to discharge.
What did they find?
A total of 366 babies were enrolled (187 at 1600g and 179 at 1800g. Baseline characteristics of the two groups revealed no statistical differences. Mean LOPS was a median of 43 days in the lower and 41 days in the higher weight group (P = .12). After transition to a crib weight gain was better in the lower weight group, 13.7 g/kg/day vs 12.8 g/kg/ day (P = .005). Tracking of adverse events such as the incidence of severe hypothermia did not differ between groups. The only real significant difference was a better likelihood of weaning from the incubator in the higher group at 98% success vs 92% on the first attempt. Putting. That in perspective though, a 92% success rate by my standards is high enough to make an attempt worthwhile!
The authors have essentially shown that whether you wean at the higher or lower weight threshold your chances of success are pretty much the same. Curiously, weight gain after weaning was improved which seems counter intuitive. I would have thought that these infants would have to work extra hard metabolically to maintain their temperature and have a lower weight gain but that was not the case. Interestingly, this finding has been shown in another study as well; New K, Flint A, Bogossian F, East C, Davies MW. Transferring preterm infants from incubators to open cots at 1600 g: a multicentre randomised controlled trial. Arch Dis Child Fetal Neonatal Ed 2012;97:F88-92. Metabolic rate has been shown to increase in these infants but skin fold thickness has been shown to increase as well in infants moved to a crib. How these two things go together is a little beyond me as I would have thought that as metabolic rate increases storage of tissue would slow. Not apparently the case but perhaps just another example of the bodies ability to overcome challenges when put in difficult situations. A case maybe of “what doesn’t kill you makes you stronger?”
The authors do point out that the intervention was unmasked but the standardization of weaning procedure and garments used in the cribs should have overcome that. There were 36% of parents who did not consent to the study so their inclusion could have swayed the results perhaps but the sample size here was large despite that. That the final results agree with findings in ELBW infants suggests that the results are plausible.
What I think this study does though is tell us overall that weaning at a smaller weight is at least alright to try once one is at minimal settings in an incubator. Will this change your units practice? It is something that at least merits discussion.
I thought I would start off my series of posts with one of the most basic reasons we do Kangaroo Care.
Thermoregulation is the process of maintaining an infant’s temperature within normal range. Thermoregulation is extremely important for the newborn (term or preterm). An infant’s body surface area is 3X greater than an adult’s, causing them to potentially lose heat rapidly, up to 4X faster. When cold stressed, infants use energy and oxygen to generate warmth. Oxygen consumption can increase by as much as 10%. Thermoregulation of the infants allows them to conserve energy and build up *reserves”.
What Happens When An infant Is Placed Skin to Skin?
When the term infant is placed skin to skin at birth, the mother’s breasts immediately start to warm and conduct heat to the infant, helping to maintain normal blood sugar levels due to the infant not having to use their own brown fat to stay warm (Bergstrom et al.,2007;Bystrova et al.,2007;Ludington-Hoe et al.,2000,2006) (Chantry,2005;Christensson et al.,1992).
Kangaroo Care maintains a Neutral Thermal Environment (defined as the ideal setting in which an infant can maintain a normal body temperature while producing only the minimum amount of heat generated from basal life-sustaining metabolic processes).
In our unit, any infant that needs an incubator to maintain their temperature can only come out to be held by Kangaroo Care instead of being bundle held. To help maintain thermoregulation we make sure the infant and parent are in a draft free area, and use 2-4 layers of blankets over the infant (you can always remove a layer if needed). Infants weighing less than 1000gms should wear some type of head cap and monitor them using the incubator’s temperature probe. Remember too, we don’t want any bras or clothing between the infant and the mother, fabric will interfere with the conductance of heat from mother to infant (Ludington-Hoe et al.,2000).
One of the interesting things about KC and thermoregulation is if a mother holds twins in KC each breast works independently to warm each infant (Ludington-Hoe, et al.,2006). Triplets? Not sure, but our mothers hold their “trips” together all the time and we have had no issues.
Now, how about the father? Does he thermoregulate like the mother? With mothers you have what is called Thermal Synchrony (maternal breast temperatures changing in response to the infant’s temperature) (Ludington-Hoe, et al.,1990;1994,2000) where the fathers chests will warm up when the infant is placed in KC but will not cool down (Maastrup & Greisen, 2010). We don’t have any issues with our fathers overheating, just lots of hair to be picked off the infant after!
It is hard to believe that I gave birth as it were to All Things Neonatal in February of 2015. After 170 published posts and so many wonderful experiences it was time for a change. I have moved the entire blog over to this new location which allows me a great deal more control over the look and feel of the site. It has been a great journey and I have gained many friends along the way. These experiences and interactions with parents, nurses, doctors, respiratory therapists, dieticians and many others have let to a tremendous amount of shared knowledge and I hope that you the reader are better for it. I am also pleased to say that the blogging and other social media venues have taken me far beyond the borders of Manitoba and allowed me to learn from others as well. As you take a look around the site you will notice there are some changes to the layout and the overall look that I hope you like. I also hope that the next 170 blog posts are as interesting to you as the first batch.
If you want to change your bookmark for the site it is now at www.allthingsneonatal.com
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When I think back to my early days as a medical student, one of the first lessons on the physical exam involves checking central and peripheral perfusion as part of the cardiac exam. In the newborn to assess the hemodynamic status I have often taught that while the blood pressure is a nice number to have it is important to remember that it is a number that is the product of two important factors; resistance and flow. It is possible then that a newborn with a low blood pressure could have good flow but poor vascular tone (warm shock) or poor flow and increased vascular tone (cardiogenic shock or hypovolemia). Similarly, the baby with good perfusion could be in septic shock and be vasodilated with good flow. In other words the use of capillary and blood pressure may not tell you what you really want to know.
Is there a better way?
As I have written about previously, point of care ultrasound is on the rise in Neonatology. As more trainees are being taught the skill and equipment more readily available opportunities abound for testing various hypotheses about the benefit of such technology. In addition to my role as a clinical Neonatologist I am also the Medical Director of the Child Health Transport Team and have pondered about a future where ultrasound is taken on retrievals to enhance patient assessment. I was delighted therefore to see a small but interesting study published on this very topic this past month. Browning Carmo KB and colleagues shared their experience in retrieving 44 infants in their paper Feasibility and utility of portable ultrasound during retrieval of sick preterm infants. The study amounted to a proof of concept and took 7 years to complete in large part due to the rare availability of staff who were trained in ultrasound to retrieve patients. These were mostly small higher risk patients (median birthweight, 1130 g (680–1960 g) and median gestation, 27 weeks (23–30)). Availability of a laptop based ultrasound device made this study possible now that there are nearly palm sized and tablet based ultrasound units this study would be even more feasible now (sometimes they were unable to send a three person team due to weight reasons when factoring in the ultrasound equipment). Without going into great detail the measurements included cardiac (structural and hemodynamic) & head ultrasounds. Bringing things full circle it is the hemodynamic assessment that I found the most interesting.
Can we rely on capillary refill?
From previous work normal values for SVC flow are >50 ml/kg/min and for Right ventricular output > 150 ml/kg/min. These thresholds if not met have been correlated with adverse long term outcomes and in the short term need for inotropic support. In the absence of these ultrasound measurements one would use capillary refill and blood pressure to determine the clinical status but how accurate is it?
First of all out of the 44 patients retrieved, assessment in the field demonstrated 27 (61%) had evidence using these parameters of low systemic blood flow. After admission to the NICU 8 had persistent low systemic blood flow with the patients shown below in the table. The striking finding (at least to me) is that 6 out of 8 had capillary refill times < 2 seconds. With respect to blood pressure 5/8 had mean blood pressures that would be considered normal or even elevated despite clearly compromised systemic blood flow. To answer the question I have posed in this section I think the answer is that capillary refill and I would also add blood pressure are not telling you the whole story. I suspect in these patients the numbers were masking the true status of the patient.
How safe is transport?
One other aspect of the study which I hope would provide some relief to those of us who transport patients long distance is that the head ultrasound findings before and after transport were unchanged. Transport with all of it’s movement to and fro and vibrations would not seem to put babies at risk of intracranial bleeding.
Where do we go from here?
Before we all jump on the bandwagon and spend a great deal of money buying such equipment it needs to be said “larger studies are needed” looking at such things as IVH. Although it is reassuring that patients with IVH did not have extension of such bleeding after transport, it needs to be recognized that with such a small study I am not comfortable saying that the case is closed. What I am concerned about though is the lack of correlation between SVC and RVO measurements and the findings we have used for ages to estimate hemodynamic status in patients.
There will be those who resist such change as it does require effort to acquire a new set of skills. I do see this happening though as we move forward if we want to have the most accurate assessment of clinical status in our patients. As equipment with high resolution becomes increasingly available at lower price points, how long can we afford not to adapt?
It is hard to be a Neonatologist who took the path through Pediatrics first and not use a Dr. Seuss quote from time to time. If your unit is anything like ours where you work I imagine you feel as if you are bursting at the seams. As the population grows so do our patient volumes. I often quote the number 10% as being the number of patients we see out of all deliveries each year in our units. When I am asked why our numbers are so high I counter that the answer is simple. For every extra 100 births we get 10 admissions. It is easy though to get lost in the chaos of managing a unit in such busy times and not take a moment to look back and see how far we have come. What did life look like 30 years ago or 25 years ago? In Winnipeg, we are preparing to make a big move into a beautiful new facility in 2018. This will see us unify three units into one which is no easy task but will mean a capacity of 60 beds compared to the 55 operational beds we have at the moment.
In 2017 we are routinely resuscitating infants as young as 23 weeks and now with weights under 500g at times. Whereas in the past anyone under 1000g was considered quite high risk, now the anticipated survival for a 28 week infant at 1000g is at or above 95%. Even in my short career which began in 1998 in terms of Pediatrics and then 2001 in Neonatology our approach in terms of comfort with the smallest infants has eased greatly. What inspired this post though was a series of newspaper clippings from 1986 and 1991 that made me take a moment to look up at the sky and mutter “huh”. When you take a trip down memory lane and read these posts I think you will agree we have come a LONG way and (in truth) in a very short time.
1986 – Opening of the New NICU at Children’s Hospital
This unit was built with 3.5 million dollars. Imagine how far that would go now…
The unit had a capacity of 18 beds but opened with only 12 and a nursing staff of 60 (compare that to 150 now!). They couldn’t open more beds due to the lack of available nurses with sufficient skills.
My favourite comment to provide some perspective was that 5 to 10 years before this time the estimated survival for infants under 1000g was 15%!
Have we ever come a long way in family centred care. Can you imagine having a baby born now at 695g whose family wouldn’t get to hold them till almost 3.5 months of age?! That is what happened in the case described in this article.
1991 – Opening of the new Intermediate Care Nursery
Did you know the old unit had 19 beds (was originally 9 babies) and expanded to 27 at this time?
It cost 3.1 million to build this unit.
The long and the short of it is that yes things are busy and in fact busier than they have ever been. Do not lose sight however wherever your practice is that you are part of a story for the ages. Things that were once thought impossible or miracles are now everyday events and you have been part of it. For those of you who read this post this will likely bring about a lot of nostalgia for you. Thirty years in medicine is not a long time and we have accomplished so much along the way. For those of you who are just starting out, imagine where we will be in 30 years from now. I for one can’t wait to read about it and wonder where we will have gone by then.