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.nonivasive-respiratory-support-niv-high-frequency-ventilation-hfv-63-638  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

 

Marijuana Coming Soon To An NICU Near You!

Marijuana Coming Soon To An NICU Near You!

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 are changing however and with the election of Mr. Trudeau as our next Prime Minister may the appetite for such a study have changed? 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?  Let’s look back at this post in 5-10 years.