Another dogma bites the dust? Two vs three hour feeding intervals for VLBW infants.

Another dogma bites the dust? Two vs three hour feeding intervals for VLBW infants.

This could turn into a book one day I suppose but I have become interested in chalenging some of my long held beliefs these days. Recently I had the honour of presenting a webinar on “Dogmas of Neonatology” for the Indian Academy of Pediatrics which examined a few practices that I have called into question (which you can watch in link). Today I turn my attention to a practice that I have been following for at least twenty years. I have to also admit it is something I have never really questioned until now! In our institution and I suspect many others, infants born under 1250g have been fed every two hours while those above every three. The rationale for this has been that a two hour volume is smaller and causes less gastric distention. This in theory would benefit these small infants by helping to not compromise ventilation or lead to reflux. Overwhelming the intestine with large distending boluses would also in theory lead to less necrotizing enterocolitis. All of this of course has been theoretical and I can thank those who preceded me in Neonatology for coming up with these rules!

Study Challenges This Old Belief

Yadav A et al published Two-hourly versus Three-hourly Feeding in Very Low Birthweight Neonates: A Randomized Controlled Trial out of India (well timed given my recent talk!). The authors randomized 175 babies born between 1000-1500g to either be fed q2h vs q3h once they began protocol feeding. The primary outcome was time to full feedings. Curiously, the paper indicates they decided to do a preplanned subgroup analysis of the 1000-1250 and 1251 -1500g groups but in the discussion it sounds like this is going to be done as a separate paper so we don’t have that data here.

The study controlled conditions for determining feeding intolerance fairly well. As per the authors:

“Full enteral feed was defined as 150 mL/Kg/day of enteral feeds, hypoglycaemia was defined as blood glucose concentration <45mg/dL [15]. Feed intolerance was defined as abdominal distension (abdominal girth ≥2 cm), with blood or bile stained aspirates or vomiting or pre-feed gastric residual volume more than 50% of feed volume; the latter checked only once feeds reached 5 mL/kg volume [16]. NEC was defined as per the modified Bells staging.”

We don’t use gastric residuals in our unit to guide cessation of feedings anymore but the groups both had residuals treated the same way so that is different but not somethign that I think would invalidate the study. The patients in the study had the baseline characteristics shown below and were comparable.

Results

It will be little surprise to you that the results indicate no difference in time to full feedings as shown in Figure 2 from the paper.

The curves for feeding advancement are essentially superimposed. Feeding every two vs three hours made no difference whatsoever. Looking at secondary outcomes there were no differences as well in rates of NEC or hypoglycemia. Importantly when examining rates of feeding intolerance 7.4% of babies in the 2 hour and 6.9% in the 3 hour groups had this issue with no difference in risk observed.

Taking the results as they are from this study there doens’t seem to be much basis for drawing the line at 1250g although it would still be nice to see the preplanned subgroup analysis to see if there were any concerns in the 1000-1250 group.

Supporting this study though is a large systematic review by Dr. A. Razak (whom I have collaborated with before). In his systematic review Two-hourly versus three-hourly feeding in very low-birth-weight infants: A systematic review and metaanalysis. he concluded there was no difference in time to full feeds but did note a positive benefit of q3h feeding in the 962 pooled infants with infants fed 3-hourly regainin birth weight earlier than infants fed 2-hourly (3 RCTs; 350 participants; mean difference [95% confidence interval] -1.12 [-2.16 to -0.08]; I= 0%; p = 0.04). This new study is a large one and will certainly strengthen the evidence from these smaller pooled studies.

Final Thoughts

The practice of switching to q2h feedings under 1250g is certainly being challenged. The question will be whether the mental barriers to changing this practice can be broken. There are many people that will read this and think “if it’s not broken don’t fix it” or resist change due to change itself. The evidence that is out there though I would submit should cause us all to think about this aspect of our practice. I will!

How much feeding volume can a preterm baby really take? It’s likely more than you think!

How much feeding volume can a preterm baby really take? It’s likely more than you think!

Since the dawn of my time in Neonatology there has been cibophobia! What is this you ask? It is the fear of food and with some flexibility in the definition I would apply this to large volumes of milk rather than the fear of food itself. Most units in the world seem to use a volume range of about 135 – 165 mL/kg/d as a range considered to mean “at full feeds”. As I was discussing this on rounds today I was quick to point out though that babies with neonatal opioid withdrawal syndrome (NOWS) frequently take in excess of 200 mL/kg/d and we don’t worry about it. The counter argument though is that these infants are “bigger” and should be able to tolerate a larger volume. As readers of this blog know I truly enjoy coming across papers that suggest a change to something considered dogma. Today is one of those days as I am choosing to explore in more depth an abstract that I posted to Twitter and Facebook last month.

On the day of this blog release I also took a poll on Twitter and found some interesting results that make this post all the more important to share. Take a look!

Are Bigger Volumes Better?

Travers CP et al chose to challenge this long held practice in their recent paper Higher or Usual Volume Feedings in Very Preterm Infants: A Randomized Clinical Trial. It was a simple yet wonderful trial that asked the question of whether for infants < 32 weeks GA at birth with BW from 1000-2500g would higher volume feedings of 180-200 vs 140-160 ml/kg/d help increase growth velocity. Randomization occurred after infants had reached 120 mL/kg/d of oral feedings. In both arms advancements from this point were the same and fortification occurrred as per usual practrice but in each arm strategies targeted individual fortification to weight gain.

The authors were seeking a 3 g/kg/d difference in growth and needed 224 infants to demonstrate this difference. They enrolled the same at a mean GA of 30.5 weeks and a BW of 1445 grams. Birth characteristics including gestational age, weight, sex, race/ethnicity, Apgar scores, head circumference, length,
and proportion of infants with a weight <10th percentile at birth did not differ between groups.

The outcomes showed differences as shown below.

Looking at the results

All in all I would say the results are a smashing success. Growth velocity was improved and not just in weight but in head circumference and length. What I find interesting is that if fortification of milk was targeted regardless of the volume used I am a bit baffled as to why the growth rate would still be better but it was. The difference in caloric intake received between groups was approximately 9 kcal/kg/day at day 7 after study entry (126 kcal/kg/day versus 117 kcal/kg/day) and 16 kcal/kg/day from day 14 after study entry onwards (139 kcal/kg/day versus 123 kcal/kg/day).

Blinding here would have been a challenge as nurses and other health care providers would have been able to calculate the expected volumes at different fluid administration levels. Nonetheless there was a difference.

The question though that many would ask is whether this better growth came at the expense of greater morbidity. Let’s be clear here that the study was not powered to look at adverse outcomes and the numbers in the above table are small but no difference was seen nonetheless. To appease the most cautious of Neonatologists I suspect a larger study powered to look at adverse outcomes will be needed. What this study does though is raise the question of whether we can and should try larger volumes. As the title suggests I wonder about getting bigger faster so one can go home. With this more rapid rate of growth can we expect a faster maturation as well? I doubt it but it is something to certainly question in a larger study!

Just how safe is feeding while on CPAP?

Just how safe is feeding while on CPAP?

This is becoming “all the rage” as they say.  I first heard about the strategy of feeding while on CPAP from colleagues in Calgary.  They had created the SINC * (Safe Individualized Feeding Competence) program to provide an approach to safely introducing feeding to those who were still requiring CPAP.  As news of this approach spread a great deal of excitement ensued as one can only imagine that in these days when attainment of oral feeding is a common reason for delaying discharge, could getting an early start shorten hospital stay?  I could describe what they found with the implementation of this strategy but I couldn’t do it the same justice as the presenter of the data did at a recent conference in Winnipeg.  For the slide set you can find them here.  As you can imagine, in this experience out of Calgary though they did indeed find that wonderful accomplishment of shorter hospital stays in the SINC group.  We have been so impressed with the results and the sensibility of it all that we in fact have embraced the concept and introduced it here in both of our units.  The protocol for providing this approach is the following.eating-in-sinc-algorithm

I have to admit, while I have only experienced this approach for a short time the results do seem to be impressive.  Although anecdotal a parent even commented the other day that she felt that SINC was instrumental in getting her baby’s feeding going!  With all this excitement around this technique I was thrown a little off kilter when a paper came out suggesting we should put a full stop to feeding on CPAP!

Effect of nasal continuous positive airway pressure on the pharyngeal swallow in neonates

What caused my spirits to dampen? This study enrolled preterm infants who were still on CPAP at ≥ 34 weeks PMA and were taking over 50% of required feeding volumes by NG feeding.  The goal was to look at 15 patients who were being fed on CPAP +5 and with a mean FiO2 of 25% (21-37%) using video fluoroscopic swallowing studies to determine whether such patients aspirate when being fed.  The researchers became concerned when each of the first seven patients demonstrated abnormalities of swallowing function indicating varying degrees of aspiration.  As such they took each patient off CPAP in the radiology suite and replaced it with 1 l/min NP to achieve acceptable oxygen saturations and repeated the study again.  The results of the two swallow studies showed remarkable differences in risk to the patient and as such the recruitment of further patients was stopped due to concerns of safety and a firm recommendation of avoiding feeding while on CPAP was made.

Table 2. Percentage of all swallows identified with swallowing dysfunction
on-nCPAP off-nCPAP
Variable Mean ± s.d. Mean ± s.d. Median (q1–q3) Mean ± s.d. Median (q1–q3) P-value
Mild pen. % 20.1±16 20 (4.5–35) 15.4± 7.6 20 (9–20) 0.656
Deep pen. % 43.7±15.4 38.5 (30–59) 25.3± 8.8  25 (18.2–32) 0.031
Aspiration % 33.5±9.4 30 (27.3–44.4) 14.6± 7 15 (9.1–20) 0.016
Nasopharyngeal reflux   % 42.8±48.5 18.2 (0–100) 44.2± 45.4 18.2 (5–92) 0.875

Taking these results at face value it would seem that we should put an abrupt halt to feeding while on CPAP but as the saying goes the devil is in the details…

CPAP Using Ram Cannulae

Let me start off by saying that I don’t have any particular fight to pick with the RAM cannulae.  They serve a purpose and that is they allow CPAP to be delivered with a very simple set of prongs and avoid the hats, straps and such of more traditional CPAP devices. We have used them as temporary CPAP delivery when moving a patient from one area to another.  As the authors state the prongs are sized in order to ensure the presence of a leak.  This has to do with the need to provide a way for the patient to exhale when nasal breathing.  Prongs that are too loose have a large leak and may not deliver adequate pressure while those that are too tight may inadvertently deliver high pressure and therefore impose significant work of breathing on the patient.  Even with appropriate sizing these prongs do not allow one to exhale against a low pressure or flow as is seen with the “fluidic flip” employed with the infant flow interface. With the fluidic flip, exhalation occurs against very little resistance thereby reducing work of breathing which is not present with the use of the RAM cannula.

A comparison of the often used “bubble CPAP” to a variable flow device also showed lower work of breathing when variable flow is used.

The Bottom Line

Trying to feed an infant who is working against a constant flow as delivered by the RAM cannulae is bound to cause problems.  I don’t think it should be a surprise to find that trying to feed while struggling to breathe increases the risk of aspiration.  Similarly, under treating a patient by placing them on nasal prongs would lead to increased work of breathing as while you may provide the needed O2 it is at lower lung volumes.  Increasing work of breathing places infants at increased risk of aspiration.  That is what I would take from this study.  Interestingly, looking at the slide set from Calgary they did in fact use CPAP with the fluidic flip.  Smart people they are.  It would be too easy to embrace the results of this study and turn your nose to the SINC approach to feeding on CPAP.  Perhaps somewhere out there someone will read this and think twice about abandoning the SINC approach and a baby will be better for it.

* SINC algorithm and picture of the fluidic flip courtesy of Stacey Dalgleish and the continued work of Alberta Health Services

Cannabidiols Coming Soon To An NICU Near You!

Cannabidiols Coming Soon To An NICU Near You!

October 17th, 2018 the personal use of marijuana became legal in Canada.   With this change in status I felt it was appropriate to consider a couple things.  First it would address an issue that affects almost all preterm infants and secondly finally acknowledge that with legalization of marijuana, the door has opened to acceptance perhaps of further medicinal uses for cannabinoids.  Who knows where things will go from here…

Marijuana and babies have for the most part had a unfriendly past.  Marijuana’s effect on the growing fetus has been a concern in past publications and women for years have been screened for it’s use along with other more illicit drugs.  More recently a large study by Warshack found increased rates of NICU admission and infants who were SGA among users but did not reveal any other significant adverse outcomes with use.  Those who have identified themselves as users have been subjected to being labelled as addicts & stoners among other names but with Canada on the verge of becoming a marijuana friendly country this is likely to change.  Interestingly, caffeine, a drug that we are all familiar with though, has a similar story in that excessive quantities have been deemed harmful in pregnancy yet it is one of the most commonly used medications in the NICU due to its beneficial effects on apnea of prematurity.

It’s Only Natural

Now before people think I have come completely off the rails, I am not envisioning a future world of hazy smoke filled isolettes or NICUs for that matter.  It is not the burning plant that may work its way into the NICU but rather the active class of drug; cannabinoids.  human-endocannabinoid-systemIt turns out that we humans have actually been built to receive such molecules as evidenced by the presence of cannabinoid receptors in our tissues and in particular our brains.  The presence of these substances is even important in birth.  Jokisch et al compared cord blood levels of endocanabinoids between those infants delivered vaginally and those by c-section without labour.  The infants born by vaginal birth had significantly higher levels of these substances in their blood demonstrating that they have a role to play in the transition to extrauterine life. These endogenously produced versions are called endocannabinoids. Furthermore breast milk contains such endocannabinoids which raises the questions of what these substances are doing there.

To answer this question an elegant study was performed in mice in which the CB1 receptor antagonist rimonabant was injected at different time points to block the effect of endocannabinoids.  When given in the first 24 hours, “milk ingestion and subsequent growth was completely inhibited in most pups (75%–100%) and death followed within days after antagonist administration.”  When examining the reason for poor milk ingestion it was an inability to suck that was the cause, rather than loss of appetite.  Although speculative, I cannot help but wonder if the infant of a diabetic mother who demonstrates poor coordination of suck might well have altered expression of cannabinoid receptors or antagonism of the same.

What Benefits Could We See From Medicinal Use?

When it comes to life in the modern NICU it is the large number of patients in need of gavage feeding that keep our census numbers high.  Whether they be the infants of diabetic mothers or survivors of extreme prematurity, many remain in hospital soley for poor feeding.  We can treat their apnea with caffeine but for years I have questioned whether an appetite stimulant might offer hope to transition such children to the home.  We are not in a position to start using cannabinoids in clinical practice yet as w have not had any trials that I am aware of outside of an animal model but I would suggest to you that this may be the next frontier.

For those that use marijuana or one of it’s other forms they will tell you there are many potential benefits and the same could be true for newborns.  There is no question that THC can be sedating and calming so could there be a role as an alternative to narcotics and benzodiazepines?  Additionally, animal models of hypoxic ischemic encephalopathy are revealing a protective effect of cannabinoids both in the short and long term.  Much like erythropoietin and melatonin have emerged as adjunctive treatments to cooling, based on animal studies we may find cannabinoids trialed in human studies before long.

What Does The Future Hold In Store For Us

I have certainly talked about this on rounds before but have not had the confidence that such studies would pass through a local ethics board.  o-JUSTIN-TRUDEAU-POT-facebookNow the winds have changed with the election of Mr. Trudeau Prime Minister and the perception of marijuana? As we become more comfortable with the benefits of cannabinoids I suspect we will see these substances come into play much like caffeine did oh so many years before.  There is no question that when people say that marijuana is “natural’ they are right in a sense.  The building blocks of THC are produced in our bodies and we have receptors anxiously awaiting stimulation by these substances.  The time for medicinal use in the NICU will come sooner or later.  Sound a little crazy?

Trials have already begun based on research in animals in the field of HIE as discussed in this article. 

CBD FOR BRAIN-DAMAGED BABIES?

 Let’s look back at this post in 5-10 years.