Necrotizing Enterocolitis: manipulating the microbiome, part 2

The Newcastle, UK, group has published an article about the intestinal microbiome of babies receiving routine probiotic prophylaxis. Abdulkadir B, et al. Routine Use of Probiotics in Preterm Infants: Longitudinal Impact on the Microbiome and Metabolome. Neonatology. 2016;109(4):239-47. The authors studied 7 extremely premature babies who received Infloran (Bifidobaterium bifidum, and Lactobacillus acidophilus) and 3 controls, also extremely premature.

Basically, they showed greater Bifidobacterium (15.1%) and Lactobacillus (4.2%) during supplementation compared to the control group (4.0% and 0%, respectively). Bifidobacterium counts stayed high following discharge, but the Lactobacillus disappeared.

Several previous studies in very preterm infants have shown extremely low, or absent, Bifidobacterial colonies, increasing that to 15% shows an enormous change in the intestinal microbiome.

The impacts of the microbiome changes on the “metabolome” of gut are also presented, the results seem to me preliminary, and as yet of uncertain significance, but there appear to be some differences between babies getting probiotics and those not.

Some of the same authors have written a review article Embleton ND, et al. Probiotics for prevention of necrotizing enterocolitis and sepsis in preterm infants. Curr Opin Infect Dis. 2016;29(3):256-61.  It is fairly brief and summarizes the data well, the abstract ends like this:

Despite current uncertainties, it is difficult for clinicians to ignore the current data, and increasing numbers now use commercially available products. It remains a matter of concern that many products lack the robust quality control most clinicians and parents would consider important for use in vulnerable populations. Head-to-head trials are needed.

Which I think is right on the money. And also brings me neatly to the next article:

Lewis ZT, et al. Validating bifidobacterial species and subspecies identity in commercial probiotic products. Pediatr Res. 2016;79(3):445-52. Mark Underwood’s group from UCDavis examined the composition of 16 formulations of probiotics that were promoted as containing Bifidobacteria, some available on-line, and others in local stores. One of the complicating factors in this field is the changes in classification that occur, so the same strain can go from being an B. longum to being a B. animalis.

They found that the advertised content of many of the products varied significantly from the true composition. Only 1 of the 16 products tested had exactly the same Bifidobacteria species in every sample as what was written on the label. In addition:

Some products were not internally consistent as both pill-to-pill and lot-to-lot variation were observed

Some producers in other parts of the world have better quality control, and more reliable composition, but it is really hard to know,if you just go to the local health food store, if you are getting what you think.

When we started using probiotics routinely a few years ago, we were fortunate that there were preparations with good quality control, and which followed GMP. Standards for probiotics for premies are extremely important.

Mark Underwood is also an author of a recent review article, Vongbhavit K, Underwood MA. Prevention of Necrotizing Enterocolitis Through Manipulation of the Intestinal Microbiota of the Premature Infant. Clin Ther. 2016;38(4):716-32. Another excellent review, the last sentence in their abstract is the following :

Shaping the intestinal microbiota of the premature infant through human milk feeding and dietary supplements decreases the risk of NEC. Further studies to identify the ideal microbial composition and the most effective combination of supplements are indicated.

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Necrotizing Enterocolitis: manipulating the microbiome, part 1

Some very interesting recent publications about NEC, so I will post a multi-part bumper posting.

The first has just been published (in tomorrow’s Lancet) Warner BB, et al. Gut bacteria dysbiosis and necrotising enterocolitis in very low birthweight infants: a prospective case-control study. The Lancet. 2016;387(10031):1928-36.

In this study the authors collected stool samples from all the VLBW infants in their NICU and froze them. They started doing this in St Louis, and then added cohorts from two other NICUs. When a baby developed NEC they analyzed all the stools up to the day of diagnosis (max 60 days), and then they found some matched controls (1 to 4 per case), with similar gestational age and birth date, they analyzed all their stools up to 30 days of age, and then every 3rd day to 60 days of age. What they call the “primary cohort” are the babies from St Louis, the “secondary cohort” was the babies from the other 2 centres, where stool collection started later.

In total they analyzed 2492 stool samples from 122 infants in the primary cohort, of whom 28 developed NEC; there were 94 controls.

The microbial community structure in case stools differed significantly from those in control stools. These differences emerged only after the first month of age. In mixed models, the time-by-necrotising-enterocolitis interaction was positively associated with Gammaproteobacteria (p=0·0010) and negatively associated with strictly anaerobic bacteria, especially Negativicutes (p=0·0019).

In the secondary cohort there were 44 infants, of whom 18 developed NEC. The results from the combined cohorts reflected what that quote above notes, with the additional finding that there was an decreased proportion of the combined Clostridia–Negativicutes class (p=0·0051) in the NEC babies compared with controls.

I am no microbiologist, so the term “Negativicutes” was new to me. It refers to a class of the Firmicutes that are Gram negative, (most Firmicutes are Gram positive, including clostridia and bacilli).

The Gammaproteobacteria include lots of the bad boys, Pseudomonads, and the Enterobacteria, which includes Salmonella, E Coli, Enterobacter, and Klebsiella.

Cuties

This simplified figure in the article points out some of the complexity of the situation, if you compare the controls between centres you can see marked differences, for example in the proportion of the Gammas that are Klebsiellae, much higher in Louisville than elsewhere. I think this actually may account for some of the differences in NEC rates between centers, the microbiology of your NICU could have a major influence on NEC, much more than how you feed the babies!

In addition, the article confirms other observations that the intestinal microbiome of babies that go on to develop NEC is much less diverse than controls.

As the accompanying editorial notes the “relative abundance of Gram-negative facultative bacilli and relative paucity of anaerobic bacteria (ie, Clostridia and Negativicutes) could represent the microbiota signature preceding necrotising enterocolitis in very low birthweight infants.”

bifidos

The authors, Warner et al. also used other techniques to examine Bifidobacteria specifically, and as this figure shows (which is from their on-line appendix), using 2 different methods (the red and the blue bars), there were very few Bifidobacteria in their babies, most having <1%. There was also no difference between cases and controls. They state the following:

 Our data also provide a microbiological explanation for the recent failure of the probiotic Bifidobacterium breve BBG-001 to prevent necrotising enterocolitis in a large and rigorous multicentre randomised controlled trial in the UK. Specifically, we found no evidence that Bifidobacteria were under-represented in the stools of infants who subsequently developed necrotising enterocolitis.

Which is true as far as it goes, but there were vanishingly few bifidobacteria in either group. The reason for the negative results from the Pips trial do need to be figured out, it may be the wrong strain, or just randomly lower effect than the other trials, with whom the 95% confidence intervals overlap. On the other hand, the Newcastle group have recently published data showing very much higher bifidobacterial concentrations among infants who received routine probiotics compared to non-treated babies.

Which I will discuss in part 2.

 

 

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Which Surfactant is best?

Singh N, et al. Comparison of animal-derived surfactants for the prevention and treatment of respiratory distress syndrome in preterm infants. Cochrane database of systematic reviews (Online). 2015;12:CD010249.

This is the sort of systematic review that I find really helpful. Some (including some of my own) end up finding little good evidence, and summarizing the results of only one or 2 small trials. That may help to point out the lack of evidence, and to stimulate future trials, but doesn’t often give enough information to really inform practice, and individual treatment decisions.

In contrast, this review includes a significant number of trials, some with respectable sample sizes, and ends up  finding significant differences between some of the surfactants that are available.

The review divides the surfactants into the following:

bovine lung lavage surfactant extract, which includes Infasurf, bLES (the Canadian one) and Alveofact

bovine minced lung surfactant extract, which includes Survanta and Surfacten (the old surfactant TA, the Japanese one)

porcine minced lung surfactant extract, which I  know as Curosurf,

porcine lung lavage surfactant, which is apparently called Surfacen.

 

The authors searched for all the comparisons that had been studied.

Most of the comparisons showed no difference in important clinical outcomes, (although some comparisons had relatively little power,) for example, bovine minced lung and bovine lung lavage surfactants were basically equivalent for all the outcomes. This was true both for prophylactic use and for rescue use.

The comparison that did show different effects was the comparison between minced bovine lung, and minced porcine lung (that is between Survanta and Curosurf), these were all rescue/treatment trials: The first outcome was mortality.

surf death

As you can see the studies are all fairly small, and individually do not show a difference, that is always a bit of a worry, as multiple small studies can inflate an effect. Nevertheless, the summary effect shows higher mortality with the bovine minced lung preparations than the porcine surfactants.

The next outcome is ‘BPD’ or oxygen requirement at 36 weeks.

surf bpd

Here there is no sign of a difference, when the outcome is expressed as a proportion of those who were enrolled into the study.

The authors of the review also present the outcome “death or BPD” which, as those of you who were at my talk in Baltimore know, I think is not an appropriate composite outcome, and those who were at the International Neonatal Collaboration INC meeting in Bethesda recently know that many of the leaders in the field are of the same opinion. The outcomes of death and BPD have different value for parents (and for society as a whole) and may not change in the same direction. I think the outcomes of Death as one outcome, and BPD as a separate outcome among surviving infants, make much more sense. Unfortunately you can’t always tell from data as presented, but, in this case, if we make the probably unsafe, but probably not very wrong, assumption that all the deaths were before 36 weeks, then you can estimate the BPD among survivors. You come up with a relative risk of exactly 1.0, (95% CI 0.85, 1.18).

So overall it seems that porcine minced surfactant leads to more survivors, but the same proportion of BPD (that is O2 requirement at 36 weeks) among surviving infants.

As I mentioned, the confidence intervals are wide, and there are several small studies, but despite these concerns, there are relatively fewer deaths with porcine surfactant, with a risk difference of 0.05 and an NNT, for one fewer death, of 20. These data suggest therefore, that if you treat 20 babies with poractant rather than a minced bovine lung preparation, there would be one more survivor.

Also there are substantially fewer babies who need a second treatment.

surf dose

The NNT here is 7, which means that for every 7 babies you treat, one extra baby will need a second dose. (In the babies in the review, a second dose was required for about 40% of the bovine and about 25% of the porcine treated).

Pneumothoraces were a bit less frequent with porcine, maybe due to chance, and if all airleak syndromes were put together, there were fewer airleaks with porcine.

For the other comparison which is of specific interest to me, that is minced bovine lung to bovine lung lavage surfactants, almost all of the data comes from the trials of Bloom which compared calfactant (Infasurf) to beractant (Survanta). Neither the prophylactic nor rescue trials showed any differences.

The manufacturers will I am sure moan that not all the surfactants within each of these groups are identical, and indeed there are some differences in the details. Calfactant, for example has around twice as much Surfactant Protein B and C compared to bLES. But there is almost no comparative data available for bLES.

Why is the porcine preparation better, that is it works faster, leads to fewer airleaks and has lower mortality?

The studies generally used the manufacturers recommended dose, which is higher for poractant than for the bovine preparations. That may be the only reason, I am not sure about that, but in any case poractant alpha is concentrated enough that the higher initial dose is easily tolerated, whereas it would mean quite large fluid volumes for the other preparations.

In Canada we are still waiting for Curosurf. It has been approved, over a year ago, but is still not being marketed. Come on Chiesi! We are waiting…

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Blood pressures in very immature babies

One recent publication initially looked very interesting from the title, Vesoulis ZA, et al. Empirical estimation of the normative blood pressure in infants <28 weeks gestation using a massive data approach. J Perinatol. 2015. Unfortunately the authors interpretation of ‘massive data’ is to collect huge numbers of samples of blood pressure numbers from a very small number of babies. They initially included 62 infants in the study, but then excluded 17 owing to inotrope use, 6 due to high-grade intraventricular hemorrhage, and 4 because they died. Leaving 35 babies.

The authors seem inordinately proud of the fact that they had 11.9 million data points, but those data points are so numerous because they collected data every 2 seconds.

Just think if they had collected at 2 kHz instead they would have had 40 billion data points!! Maybe they would only have needed 10 babies, then they would still have had a billion data points.

Obviously collecting BP data from a very small number of babies is likely to mean that you won’t have the power to see any effects on BP of gestational age; eliminating all the babies who were treated with inotropes is likely to worsen this effect, as the babies with the lower blood pressures will be eliminated, so you are likely to be left among the most immature babies only those who had higher than average BP. Therefore it is not surprising that the authors state that GA and birth weight were not associated with BP.

Let’s get this straight, because a massive data approach, that is, analyzing BP data collected electronically from large numbers of babies, could actually be helpful. But it is the number of babies that is important, not how often you read the BP from the monitor.

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Unilateral DNR orders?

A paper from Mark Mercurio and colleagues has been making some waves. In it they address the question of unilateral DNAR orders (previously called Do Not Resuscitate DNR orders, but now often referred to, more accurately as Do Not Attempt Resuscitation DNAR orders; as most extensive cardiac resuscitation attempts (CPR) fail, the ‘attempt’ is an important addition.)

The point made in the article is that there is no moral obligation to offer treatments that we know will not work. Therefore when we know something is truly futile we can unilaterally decide not to do it.

(There is another part of the arguments that I shall come back to).

In the neonatal period, once you are admitted to an NICU, the only babies for whom there is a reasonable chance of success of cardiac massage and advanced resuscitation are infants with arrhythmias. In general, neonatal CPR (after the delivery room) is indeed “physiologically futile”, it just doesn’t work. At least if by “success” we mean survival to discharge. But that is not the only definition of “success” that might be of value to a family. Sometimes we can get the circulation going temporarily again in order to allow time for an out-of-town family to arrive, sometimes we can give a family who aren’t yet ready to say goodbye a few more minutes. I think those can sometimes be reasonable indications for doing something that we don’t expect to lead to long-term survival, if we can assure that the infant isn’t suffering as a result.

Nonetheless CPR has also become somewhat of a ritual, and is seen by some families as showing that their child is valued, even though the chances of success are very poor, or even zero: the fact that it was tried show that we cared about their infant. Explaining the reality of the situation takes more time and effort than writing a unilateral DNAR, accompanying parents as their child dies is far more emotionally draining, and time consuming, than just writing DNAR and leaving the room.

I think also very important are the consequences of a unilateral DNAR, consequences other than not getting DNAR, once a DNAR order is written there is a tendency to not use other measures of intensive care, even if the intention is just to avoid cardiac massage, children with a DNAR order are less likely to be ventilated, less likely to receive other interventions which do have a chance of success, they are less likely to be closely monitored, and so on. So you can’t consider DNAR orders in a vacuum, something which is not really addressed in this article, but it should be made clear, just because cardiac massage is extremely unlikely to work for a patient doesn’t mean they shouldn’t get oxygen (for example). There is actually empirical evidence that this occurs, as well as personal experience.

I think that a DNAR order is often seen as short hand for, “we are giving up on this baby”, which is why there is this trickle down effect on other interventions.

Writing a DNAR order unilaterally is more of an indication of a lack of respect for the parents input, and the parents role and values.

I have written very few DNAR orders in the last few years, and then only after discussions with parents, more commonly, when an infant is deteriorating, it is important to take time to sit with the parents, explain what things might make a difference, explain those things that will not help, including sometimes, explicitly, cardiac massage. If a baby has a persistent pH less than 7 and there is no real prospect of improvement you can say to the parents, I’m so sorry but X (use their name!) is dying, would you like to hold him for a while? Depending on how you say that, you may not have to discuss cardiac massage at all, and accompanying parents while that all happens can often avoid any demands for further inappropriate therapy.

On the other hand I think that what Marc Mercurio is saying is mostly correct, that when we ‘know’ (as much as we ever know anything) that CPR will not work, there is no obligation to perform it. In other words, if I am certain that a baby who is deteriorating as a result of having profoundly underdeveloped lungs will not have any reasonable chance of successful return of circulation if the heart should stop and I initiate CPR, then I am not under a moral obligation to perform CPR. I do however, think I am under a moral obligation to explain that situation to the parents, if they ask for CPR.

What to do if at that point the parents ask “please doctor, at least give it a try, I still hope for a miracle”? Bill Meadow and John Lantos have advocated what they erroneously call a “slow-code”, what they advocate is complying with the parents wishes, but as there is no universal standard for content or duration of a code in the NICU, early termination of the CPR when there is no response to the first dose of epinephrine, would be medically and ethically appropriate. I agree with this, and indeed I have done it once or twice (in 30 years of practice), when parents can’t agree to forgo cardiac massage, then a real code (not a slow code) but a brief real code can respect the wishes of the parent without harming the child or the health care team.

You could also say that we don’t actually need a DNAR order, any more than we need a Do Not Attempt ECMO, or Do Not Attempt Hemo-Dialysis, I think though that Cardiac Massage is different, it has become part of the consciousness of the public. Partly as a result of movies and TV shows, it is expected that when the cardiac monitor alarm goes off, the code team will run into the room and start the resuscitation; it is that expectation that needs to be addressed.

There is one point in the article by Mercurio and others that gives me some concern, that is the meaning of the phrase “with the possible exception of the most extreme cases, (DNAR) should not be written based on quality of life prognosis”. “Extreme” is a term that will not be interpreted equally by everyone. I think that should be addressed somehow, a child who is irreversibly comatose, for example, could be so extreme that, even if they had an acute arrhythmia with a chance of successful immediate resuscitation, the option of not attempting resuscitation could be considered ethically valid; but to do so against the wishes of the parents? I would say that only if there is no opportunity to discuss it with the parents should that be considered, and usually in such a situation there hasn’t been enough time for reflection among the care team either.

The authors introduce a term that I wasn’t aware of, ‘dysthanasia’ the “exaggerated prolongation of agony, suffering, and death of the patient”, clearly something to be avoided, but can we make that definition before the patient actually dies? If we can avoid ‘agony’, and I think we almost always can these days, then we can avoid dysthanasia; and if the term only applies to those who die, then you can’t really use the term until afterwards, unless you are certain the baby is dying.

The reason that I said some waves were made by this article is that Mark has also recently been a co-author with the other co-author of this article, of a questionnaire study published last month. In that article the authors had asked neonatologists whether a unilateral DNR order was acceptable for ‘patients with no hope of survival’, or in another case where there was ‘serious concern about very profound intellectual disability’. Most respondents felt a unilateral DNAR order was acceptable in the first case, and very few in the second case. In the discussion they state this proviso:

However, there may be extreme examples of neurological disability, not covered by these vignettes, for which a unilateral DNAR order would be considered acceptable to many neonatologists and others. Current debate regarding resuscitation for patients with Trisomy 13 or 18 may, at least in part, be tied to this question.

I think the combination of these 2 articles has led to some people thinking that unilateral DNAR orders might be considered acceptable for babies with trisomy 13 or 18.

Certainly infants with T13-T8 should not be considered under the term, ‘dysthanasia’, the research of Annie Janvier, Barb Farlow, and Ben Wilfond has shown that parents think that their children with T13/T18 do have some more pain than others, but they are not in constant pain, and their quality of life is good to excellent, according to the parents. The babies also show some developmental progress, smiling, responding to their parents, letting their needs be known, see this table for example from the article by Janvier, Farlow and Wilfond, which shows the proportion of children with trisomy 13 and 18 at various ages who demonstrated the behaviour.

TABLE 4

Neurodevelopmental Milestones of Children With Full T13-18 Who Are Still Alive and at Least 1-Year-Old (n = 64)

Milestones 1–3 y, % (n = 21) 3–10 y, % (n = 20) More than 10 y, % (n = 23)
Smile 100 100 100
Laugh 95 95 96
Point at objects 5 37 65
Says “mama” or “papa” 24 45 35
Plays with toys 86 95 100
Rolls over 90 100 100
Sits up 24 60 91
Stand with assistance 24 85 91
Stand without assistance 0 20 17
Walk with a walker 5 50 74
Walk unassisted 0 10 0
Eats by mouth 86 75 87
Eats alone 10 15 39

So to get back to the point of this long and rambling post, unilateral DNAR orders can usually be avoided, almost always should be avoided, and should certainly not be applied to babies with trisomies 13 or 18, or other babies with intellectual disability. I think writing a DNAR for a stable baby with a ‘quality of life’ issue against the parents wishes is really problematic, fortunately I have never had parents of a brain-dead child, or a child in a persistent vegetative state ask for CPR.

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New achievements!

Neonatal research has now passed a total of 400,000 page views since it started, thanks to many people for their encouragement

My researchgate profile now shows over 5,000 citations of articles I have authored, or co-authored. Sometimes when you publish research you don’t know if anyone is going to read it, or take any notice of what you have worked on; It is  gratifying that almost everything I have published has at least one or two, and most over 20 citations, which might mean that people found them helpful, or at least they referenced them in order to criticize them! The most highly cited articles are joint endeavours; both position statements from AAP and CPS, and multi-center trials, which is as it should be.

My talk at the PAS meeting was live-tweeted! A first for me I think, thanks @TexasKidDoc

 

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Death of a twin, further resources.

I recently wrote about the work from Newcastle in the UK about supporting parents who lose one of a pair of twins during the perinatal period. Nick Embleton wrote a comment about that post noting that they now have put some of their resources on-line.

Apart from stealing the title of their website from this blog, (they call it neonatalresearch.net, which is such an obscure name for a website about research in neonatology that I am sure they stole it from me) as I say, apart from that, there is a page about their project on the loss of one infant from a multiple birth which includes the guidelines they are developing. They also have a teaching pack available if you fill in a short survey.

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Follow up of the PREMILOC post

Further to my post about the PREMILOC trial of routine hydrocortisone supplementation in extremely preterm infants, I received an email response from Olivier Baud, who was generally in agreement with my comments, but doubts the validity of adding the data of Biswas to the off-the-cuff meta-analysis that I presented.

First of all, I appreciate the real rigor required to perform a systematic review/meta-analysis correctly. I put the data together quickly to give me (and my readers) a quick view of where the data place us currently; an appropriately performed SR may well give a somewhat different interpretation, but what we can say is that, at present, the data are not at all overwhelming, and it is appropriate to wait until someone does the synthesis properly.

Secondly, I appreciate that the inclusion of Biswas is questionable, it was an RCT of both tri-iodothyronine and hydrocortisone. Infants under 30 weeks gestation were eligible if they were ventilated and less than 5 hours of age. Given that the only effect of the T3 appears to be a suppression of endogenous thryoid function with no beneficial pulmonary effects, I think a case can be made for including it, but I am certainly open to the idea that removing it from the analysis should be considered, at least as a sensitivity analysis. So I have done that, and it makes little difference to the results, neither death nor BPD are “statistically significant” when Biswas is removed, but the combined outcome death or BPD has an upper confidence limit which is slightly further away from 1.0. Relative risk without Biswas 0.86, 95% CI 0.76, 0.96.

Dr Baud also noted that the follow up of the babies in the PREMILOC trial is near to complete. Hopefully we will have some more answers soon.

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Inhaled steroids to prevent BPD, another trial.

This time from Japan, Nakamura T, et al. Early inhaled steroid use in extremely low birthweight infants: a randomised controlled trial. Archives of Disease in Childhood – Fetal and Neonatal Edition. 2016. 211 babies with a birth weight less than 1000 grams were randomized between June 2006 and Dec 2009; if they were still intubated at 24 hours they received a metered-dose inhaler with either fluticasone or placebo, from which they had 2 ‘puffs’ (total dose of 100 microgams) per day for as long as they were intubated (maximum 6 weeks). The initial plan was to randomize about twice as many babies, but they ran out of money.

The primary outcome variable was going home on oxygen, which I think is a more important outcome than oxygen need at 36 weeks, needing oxygen at home has much more impact on the family than O2 at 36 weeks. However, even in a blinded trial, criteria for needing home oxygen should be clear, so that the external validity of the result can be assessed. I don’t know if the criteria for home oxygen in Japan are the same as for my babies, for example. I can’t find any criteria for home oxygen in the trial report.

The babies were followed until 3 years of age with a very high rate of retention of the subjects, almost all of the survivors were evaluated.

Basically there was no effect. No improvement in discharge without oxygen, and no impact on neurological or developmental progress.

There were a couple of subgroups that had a difference in the primary outcome, the middle stratum of gestational ages, 24 to 26 weeks, had a different (possible positive effect of the steroids) effect to the other 2 strata, but I don’t see a statistical evaluation of the interaction, so even though the result is different to the other strata we don’t know if that difference is itself statistically significant.

Babies who had a history of chorioamnionitis also might have had more of an effect, and babies with evidence of RDS might also have had more of an effect, again, for neither of these sub-group comparisons is there a test of the significance of the interaction term.

One surprising aspect of this study is how few of the babies received antenatal steroids; less than 43% in each group. Why? I think its questionable ethically to perform studies when a simple, safe, proven, intervention is not being applied. Similar studies in other populations will usually have over 80% antenatal steroid use, and most of the missed patients are those that deliver too quickly to get a benefit. (80% of the babies were delivered by cesarean section, in contrast, so they were getting active perinatal care). To give the authors the benefit of some doubt, the trial entry criteria may have partially selected babies without antenatal steroid coverage, as they are the ones more likely to be still intubated at 24 hours of age. But I don’t think this can be the entire reason for this very low coverage with antenatal steroids, the recent Neurosis trial for example had 90% antenatal steroid use for a similar group of babies.

What this study shows is that in babies with a totally inadequate level of coverage with antenatal steroids, postnatal inhaled steroids don’t have much detectable effect on long term oxygen requirements, or on longer term development.

So where do we stand now, with these recent early pulmonary steroid studies? I think there is still room for a well-powered trial; I’m not sure if budesonide mixed with surfactant and given a few times, with each dose of surfactant for example, would be preferable, or an inhalation (of budesonide of even fluticasone) given over the first days and weeks of assisted ventilation make most sense. This new trial and the modest benefits in the Neurosis trial make me wonder if an inhaled aerosol is likely to give much benefit.

Needing oxygen at hospital discharge, and other effects which are of consequence for the life of the family (such as re-admission for respiratory indications during the first year of life) and developmental and neurological progress of the infants should be the outcomes of interest, I think, but a wide consultation of parents to ask them what is most important as an outcome for such a trial would be even better.

 

 

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Late surfactant supplementation

After the initial phase of surfactant deficiency of the very preterm infant, inhibition and destruction of surfactant are common, the inflammation of the oxygen exposed preterm lung is probably important in the pathophysiology of bronchopulmonary dysplasia, and the adverse effects on surfactant function have led to trials of later surfactant supplementation, in the hope that lung injury might be reduced.

Previous trials have not shown much benefit (Laughon M, et al. A Pilot Randomized, Controlled Trial of Later Treatment With a Peptide-Containing, Synthetic Surfactant for the Prevention of Bronchopulmonary Dysplasia. Pediatrics. 2009;123(1):89-96., Ballard RA, et al. Randomized Trial of Late Surfactant Treatment in Ventilated Preterm Infants Receiving Inhaled Nitric Oxide. The Journal of pediatrics. 2015.) there are some short term improvements in gas exchange, but no longer term benefit is evident. The details of these studies differ, Laughon and colleagues gave ‘late’ surfactant (1 of 2 doses of lucinactant, Surfaxin) or placebo to 139 infants with birth weight 600 to 900 grams, on ventilators between 3 and 10 days of age, (when they started the study it was just day 3). Ballard’s group studied 511 ELBW infants still intubated at 7 to 14 days of age, all of whom were getting inhaled nitric, and half were randomized to get up to 5 doses of Infasurf.

The new trial was a French multicenter study: Hascoet JM, et al. Late Surfactant Administration in Very Preterm Neonates With Prolonged Respiratory Distress and Pulmonary Outcome at 1 Year of Age: A Randomized Clinical Trial. JAMA Pediatr. 2016;170(4):365-72. 118 infants of less than 33 weeks gestation were randomized at 14 days if they were still ventilated and needing more than 30% oxygen. Treated babies received one dose of poractant (Curosurf) or placebo, and the primary outcome variable was time to first successful extubation, which was clearly defined, as were the criteria for when you should try to extubate a baby. The primary outcome was not affected by surfactant. 35.7 days compared to 38.3 in the controls, with wide standard deviations of about 20 days.

Oxygen needs did decrease after surfactant for about 24 hours, but no other short term clinical benefits were shown. Oxygen needs at 36 were not different; there were some minor effects at 1 year of age, fewer surfactant babies than controls had been re-admitted for respiratory problems, but that is about it.

One could ask why doesn’t this work? The rationale is reasonable, and several studies have shown short term responses; but when you put this together with the data from the Ballard study, which had some similarities, and a much bigger sample size, there doesn’t seem to be much of a signal. Maybe a single dose is not enough? But the Ballard study allowed up to 5 doses. Maybe it isn’t the right surfactant? But Curosurf has all the goodies that you would want. Maybe it was the wrong group of babies? But the patient selection was practical and reflects babies who have long-term problems.

I think the answer is that the surfactant dysfunction is probably more of an epiphenomenon, an indicator of the on-going inflammation and dysfunction of the lungs of the extremely preterm baby, rather than being causal.

Or perhaps a mixture of surfactant and steroids would be a better prospect? If direct pulmonary administration of steroids is effective when given early, maybe giving the combination later would be more effective than either steroids or surfactant alone. Which will lead me on to the next post, another trial of pulmonary steroid treatment, this time from Japan.

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