Surfactant and inhaled nitric oxide make beautiful music together

Surfactant and inhaled nitric oxide make beautiful music together

If you work in Neonatology you no doubt have listened to people talk in rounds or at other educational sessions about the importance of opening the lung. Many units in the past were what you might call “peepaphobic” but over time and with improvements in technology many centers are adopting an attitude that you use enough PEEP to open the lung. There are some caveats to this of course such as there being upper limits to what units are comfortable and not just relying on PEEP but adding in surfactant when necessary to improve pulmonary compliance.

When we think about giving nitric oxide the importance of opening the lung can’t be stressed enough. I have heard it said many times when a baby has been found to be a “non responder” to inhaled nitric oxide that they may have been so because the lung wasn’t open. What we mean by this is that the distal alveoli are open. One can administer all the iNO in the world but if the majority of alveoli are collapsed the drug can’t get to the pulmonary vasculature and cause the pulmonary vasodilation that is so sorely needed in the presence of hypoxemic respiratory failure. Surfactant and inhaled nitric oxide in the presence of hypoxemic respiratory failure could be a great combo as one would help open the alveoli and then the iNO could address any pulmonary vasoconstriction which might be exacerbating the hypoxemic state.

Study Tests This Theory

Researchers in Chile led by Gonzalez A published Early use of combined exogenous surfactant and inhaled nitric oxide reduces treatment failure in persistent pulmonary hypertension of the newborn: a randomized controlled trial in the Journal of Perinatology. The concept of this study was to compare in a double blind RCT for 100 patients (based on a power calculation looking for a 25% reduction in treatment failure) whether provision of surfactant as up to 2 doses and iNO would be better than just iNO alone. Included infants needed an oxygenation index (OI = MAPXFiO2/pO2) of 20 or more to qualify and treatment failure was an OI of 40 or more. The patients recruited were similar in common characteristics including types of conditions that would benefit from iNO. RDS, meconium aspiration syndrome and pneumonia certainly have been shown to benefit from surfactant before while in the PPHN category that is questionable. In order to ensure that it was not just the primary disease but pulmonary hypertension that was present as well, all patients required confirmation of pulmonary hypertension prior to enrollment via ECHO with either a TR jet indicating a pulmonary pressure at least 2/3 of systemic or right to left shunting at the ductal or atrial level.

The results of the study demonstrated a clear difference in the primary outcome.

Patients receiving the combination of surfactant prior to starting iNO showed a faster reduction in OI than those receiving iNO alone. In fact the reduction in primary outcome of treatment failure was over 50% different while the power calculation had been based on only a 25% difference. That’s ok as this means there were more than enough patients to demonstrate a difference. As a secondary outcome the rate of ECMO or death was also different between the groups favouring use of surfactant.

It works so now what?

Who doesn’t like seeing a study that confirms what you have long believed. I feel that this study validates the teaching I received throughout the years about ensuring the lung is open before giving iNO. There are some caveats to this however. About 90% of the patients studied had conditions present (RDS, MAS, pneumonia) for which surfactant would have been indicated anyway. If this study had been done let’s say in patients with asphyxia induced pulmonary hypertension and clear lungs the surfactant may have made no difference as the lungs were already open. I mention this as I don’t think readers of this analysis need to jump to the conclusion that every time there is a patient with PPHN that you MUST give surfactant. What I think this illustrates though is the importance of first asking the question if iNO is being considered “Have I opened the lungs?”. The next time you encounter such a patient consider whether you are using enough PEEP and whether surfactant is indicated. The bottom line is if the lung isn’t open then all the iNO in the world isn’t going to make much difference!

Time to say goodbye to INSurE and hello to IN-REC-SUR-E?

Time to say goodbye to INSurE and hello to IN-REC-SUR-E?

Intubate-Surfactant- Extubate or INSURE has been around for awhile. The concept is to place an ETT while an infant is first on CPAP and then after pushing surfactant in quickly remove the ETT and put back on CPAP. This does not always go as planned though. If after surfactant the FiO2 remains above 30% many people would keep the ETT in place as they would surmise that the infant would fail if the tube was removed. They would probably be right.

Sustained inflations have fallen out of favour ever since the SAIL trial results were published and written about here . Having said that, the concept of using sustained inflation is to open the lung and expand closed alveoli to improve both oxygenation and gas exchange. Much like giving inhale nitric oxide to a collapsed lung is unlikely to make much difference, the question could be asked whether giving surfactant to a lung that is most collapsed will fail to deliver this compliance improving medication to the areas of the lung that most sorely need it. Our Italian colleagues therefore decided to undertake a study to look at providing surfactant to lungs after a recruitment manouver and see if this made a difference to the meaningful outcome of extubation failure after surfactant provision. The results are intriguing and as such here we go in looking at the study.

Optimizing Lung Expansion

The trial is the Lung recruitment before surfactant administration in extremely preterm neonates with respiratory distress syndrome (IN-REC-SUR-E): a randomised, unblinded, controlled trial and involved 35 NICUs in Italy. All infants enrolled were born from 24 + 0 weeks to 27 6/7 weeks gestational age at birth and all < 24 hours of age at enrollment. Each baby had to be on CPAP at the time of randomization and meet prespecified failure criteria of FiO2 of 0·30 or greater for target SpO2 of 87% to 94% for at least 30 min or in 10 Infants for rapid deterioration of clinical status or if pCO2 was > 65 mm Hg with a pH less than 7·20. Regardless of which arm they were randomized to all infants received 1-2 sustained inflation breaths using 25 cm H2O for 10-15 secs using a t-piece resuscitator after being started on CPAP as was the practice at the time. After randomization which could not be blinded, patients were then either given surfactant via INSURE without any further strategy for opening the lung or received the IN-REC-SUR-E approach. The latter involved putting the infant on high frequency oscillation starting with settings of mean airway pressure 8 cm H2O; frequency 15 Hz; ΔP15 cm H2O; and inspiration to expiration ratio of 1:2. Using this modality infants underwent stepwise recruitment methods prior to administering surfactant (poractant). The primary outome was the need for mechanical ventilation within the first 72 h of life. Infants met the primary outcome if they were not extubated within
30 min after surfactant administration or required reintubation before 72 h of life.

The Results

Based on a power calculation the authors needed 103 infants in each arm and they recruited 107 in the treatment and 111 in the control arm. In the per-protcol allocation 101 received the treatment and 111 the contol. While the strategies for extubation were not set out to be equal (units were allowed to extubate to anywhere from +6 to +8 for pressure levels), the groups were not different 7·0 cm H2O, SD 0·4 for the experimental group and control arms. Given the steps taken to open the lung in the lung recruitment arm, the FiO2 was lower at 28% prior to surfactant provision in the treatment group than in the usual INSURE approach at 42% prior to surfactant provision. All infants were extubated within 30 minutes of receiving surfactant. As the results demonstrate, whether there was an intention to treat analysis or per-protocol analysis the babies who received the intervention were more likely to remain extubated. The number needed to treat was 7 which is a pretty powerful measure. Interestingly, looking at secondary outcomes there are some interesting trends as well including less mortality which on a per-protocol analysis was significant but also a trend towards more PVL at 9% in the treatment arm and 4% in the control. The mean times to surfactant administration were 4 hours in the treatment group and 3 hours in the control but the high frequency manoeuvre had a mean duration of only 30 minutes. It is possible that the use of high frequency could have blown off CO2 to very low levels but I am uncertain if the short reduction in pCO2 could have contributed significantly to reduced cerebral perfusion if that trend is representative of something. Interestingly, pneumothroaces were not different between groups as no doubt as a reader you might wonder if use of high pressures to recruit the lungs when they are non compliant might have led to air leaks.

So it worked, now what?


First of all, the results to me make a lot of sense. Opening the lung before delivering surfactant and then seeing better chances of staying extubated doesn’t really surprise me. Some questions that come up now for me would be how this strategy would fare in those who are older at birth. I suspect given the greater chest wall support and lower likelihood of severe RDS this strategy might be even more effective at reducing FiO2 or perhaps CPAP need in terms of duration after extubation. I would think it unlikely to make a difference in reintubation though as most would remain extubated regardless. That is for another study though with a different outcome.

There will be centres that don’t like the use of HFOV for recruitment so what other strategies could be used in lieu of this? I hate to say it but there will also be calls to have a much larger study specifically designed to look at the secondary outcomes. Would a larger study find a significant increase in PVL or demonstrate that it was just a random finding? Might mortality be proven to be lower and even more so?

Regardless of the above what I think this paper does is give us reason to pause before giving INSURE and ask ourselves if we have done what we can to open the lung after intubating before rushing to squirt the surfactant in. Maybe increasing the provided PEEP and lowering the FiO2 somewhat before giving surfactant will help with distribution and increase your chances of first being able to extubate and secondly when you do keeping the tube out!

Time to say goodbye to INSurE and hello to IN-REC-SUR-E?

What are all these plastic tubes in my baby for?

If you have a baby in the NICU there is a pretty good chance there will be at least one piece of plastic inserted into your child at some point. We have all sorts of “lines” and tubes that may be present depending on the conditions your baby develops. What follows is a primer on what they are all for.

IVs

I thought I would start with the easiest one since when you gave birth the team delivering you put one in you as well. The IV in the neonate is typically put in a hand or foot rather than the crease at the elbow as we like to save the bigger veins for something that we will talk about later on. Typically the IV provides sugar water (D10 most typically which is 10% sugar in water) to provide your baby with enough sugar to satisfy their metabolic needs. If a baby is older at birth but has difficulty breathing, having this type of access allows us to give them sugar and energy while not feeding them and letting their breathing settle. Putting food in the belly may sound like a necessity but they will be fine for awhile on dextrose which will allow their breathing to settle without having a full stomach pushing up on their diaphragm.

Umbilical Catheters

These come in two forms; the umbilical venous and arterial catheters. The easiest way to think of these are as long IVs like the one you may have had in your hand during delivery. These are long and on the venous side allow us to provide nutrition to your child either with sugar water (dextrose) or total parenteral nutrition (TPN). We can also give medications which can be tough on small veins in the hand or feet such as those to help with boosting blood pressure. The arterial catheter on the other hand allows us to monitor your baby’s blood pressure continuously. It also gives us a way of drawing blood when we need to test a number of things such as how your baby is breathing (an art gas) or checking their biochemistry such as when you hear us order “lytes” which checks salt and water balances in the body. By the way, putting these lines in does not hurt as there are no nerve endings in the umbilical cord.

Nasogastric Tubes

These plastic tubes go from the nose (or mouth if it is an orogastric tube) into the stomach. When your baby is too preterm to know how to suck, swallow and breathe without inhaling their food it is safest to provide their milk through one of these tubes. They are very common!

Endotracheal tubes

When your baby is unable to breathe on their own they may need to be put on a ventilator. The ventilator attaches to an endotracheal tube and helps your baby get oxygen in and carbon dioxide out. These tubes can also be used very briefly to administer surfactant which makes it easier for your baby’s lungs to open and take air in. You may hear the medical team refer to the INSURE approach when using the tube in this way which stands for Intubate, Surfactant, Extubate.

Chest Tubes

Thankfully these tubes are not needed as much as they used to be. When air gets in between the lung and the chest wall we call that a pneumothorax.

This air can build up and make it very difficult for the underlying lung to open and fill with air. When that happens your baby’s oxygen levels drop and the carbon dioxide rises. These tubes will be put in to drain the air and relieve the pressure. Once they stop “bubbling” the tube will be clamped and then pulled out if no air reaccumulates. You may also see these tubes placed when a baby develops fluid in the same space called a pleural effusion. In that case you are trying to get rid of the fluid rather than air that has found its way in between the lung and the chest wall.

Cycled vs Continuous Phototherapy. Are breaks ok?

Cycled vs Continuous Phototherapy. Are breaks ok?

Phototherapy is one of the “bread and butter” treatments in the newborn. For sure it has gone through changes over the years as different light sources have been developed that provide more limited spectrums of blue/green light wavelengths. Gone are the old long white tubes in favour of special blue light emitting banks of lights and with it bilirubin levels are effectively dropping quickly worldwide. There have been a couple concerns raised with phototherapy over the years. One concern has been the risk of DNA damage as shown by Ramy N et al in Jaundice, phototherapy and DNA damage in full-term neonates. It was found in this study that the duration of phototherapy but not it’s intensity were related to the extent of methylation of DNA which is a marker of damage. Shorter durations would therefore be preferable. Repair of damaged DNA is thought in some ways to contribute to risk of cancer so although this has not been demonstrated with phototherapy the concern has been raised before. The other concern pertains to the ELBW infant with very thin skin. In the randomized trial for babies under 1000g entitled Aggressive vs. conservative phototherapy for infants with extremely low birth weight. In this trial a lower threshold for starting phototherapy was used in the “aggressive group”. The findings of this study in a preplanned subgroup analysis was that the babies from 500-750g that had a lower threshold for starting and continuing phototherapy had a trend towards a higher mortality; relative risk, 1.13; 95% CI, 0.96 to 1.34 as the CI just crossed 1. With this information in the literature it stands to reason that the question would come up as to whether continuous phototherapy is needed or whether one could use cycled intermittent phototherapy to give infants “phototherapy breaks”.

Such a study has now been published

This study enrolled babies with birthweights between 401 – 1000g and Initially randomized using a 1:1:1 ratio to 3 treatment groups: continuous PT (usual care), a PT regimen of 30 minutes or more per hour for each cycle, or a PT regimen of 15 min/h or more. The minutes per hour of PT could be increased for the cycled if TSB values reached specified thresholds. After the first 100 patients a planned analysis was done and the 30 minute group was ended as there was no difference between this group and the 15 minute one. The light sources and spectral irradiance (combination of intensity and distance from the patient) used were all the same and collection times for serum bilirubin levels were standardized as much as possible. Bilirubin levels were collected daily for the first 7 days and anytime infants were on phototherapy. The authors also included a stepwise prolongation of phototherapy for the shorter cycled groups if bilirubin levels were not responding to the provided phototherapy. I have to say they really did a good job of removing as many potential variables to outcome as they could!

The primary outcomes were mean peak TSB levels and mean PT hours through day 14 across all centers and predischarge wave V latency brainstem auditory evoked potential (BAER). In total 305 infants were randomized in the study and the interestingly the study was stopped at that point as a larger study was approved to obtain more precise estimates in the future around mortality and morbidity as a primary outcome. During the trial the authors received approval to do so with this new primary outcome and so we have what we have to analyze.

The Results

The authors found that there was no difference in the mean peak bilirubin even among high risk patients when given cycled phototherapy for 15 minutes an hour vs continuous. The total amount of hours of phototherapy was approximately halved. No statistical difference in mortality was observed although as mentioned above this was not the primary endpoint of the study.

Looking at duration of phototherapy in terms of hours per day over the first two weeks is shown below. Although a pre-specified plan was in place to increase time as needed to decrease bilirubin levels the amount of time remained fairly consistent for the cycled group with some increase needed in the early days which would be expected given the typical higher biirbubin tendency in the first week of life.

The BAER tests did not demonsrate any difference between the children who had cycled or continuous phototherapy suggesting that no added neurotoxicity occurred from interrupting phototherapy.

What can we take from this?

All of these infants were ELBW and wth that had very thin skin. Would cycled phototherapy be as effective in more mature infants? As the authors of the study point out, there have already been several trials in more mature infants demonstrating such effects and arguing that continuous phototherapy is not needed. At the very least this paper and the others before it would argue that interrupting phototherapy to allow breastfeeding or some skin to skin time with the mother or father should be acceptable. In the past I can remember many instances of having ordered intensive phototherapy and then questioned whether mom can breastfeed as technically it is supposed to be continuous. With this information I would suggest that continuing to work on oral feeding skills at the breast is reasonable. Clearly this won’t work in the population studied here as they are too small but for the larger infants there would not seem to be harm.

I suspect the larger study to come may change practice if a higher mortality is indeed shown for continuous phototherapy but for now we will need to wait and see. In a few years we will get the chance to review that study here.

Time to say goodbye to INSurE and hello to IN-REC-SUR-E?

Seizure control. Tried and true or the new kid on the block?

Phenobarbital at least where I work has been first line treatment for seizure control for as long as I can recall. We dabbled with using phenytoin and fos-phenytoin in the past but the go to tried and true has been phenobarbital for some time. The use of this drug though has not been without trepidation. Animal studies have linked phenobarbital to increases rates of cerebral apoptosis. Additionally, in a retrospective comparison of outcomes between seizures controlled with phenobarbital vs Levetiracetam, the latter came out ahead in terms of better long term developmental outcomes. This study from 2013 was entitled Adverse neurodevelopmental outcomes after exposure to phenobarbital and levetiracetam for the treatment of neonatal seizures. Purists of course would argue the need for a prospective trial and that is what we have to chat about here.

Levetiracetam vs Phenobarbital

The study in question was a multicenter randomized phase IIb trial (searches for a dose that provides biological activity with the minimal side effect profile) that compared two doses 40 mg/kg and 60 mg/kg of Levetiracetam with standard doses of phenobarbital. The study was done by Sharpe C et al and called Levetiracetam Versus Phenobarbital for Neonatal Seizures: A Randomized Controlled Trial.

In this study patients were randomized to receive levetiracetam or control phenobarbital treatment group in a 60:40 allocation ratio by using a block randomization strategy and stratified by site. The trial design is shown in the diagram below.

The study was designed to not delay institution of the accepted treatement with phenobarbital as usual first line treatment of seizures by more than 1 hour. The strength of this study was that the authors used electrographic seizures confirmed by continuous EEG monitoring. The efficacy of medication effect was blindly interpretted by two independent electrophysiologists. in other words the authors went out of their way to ensure these were real seizures and moreover that any changes to medications were decided upon after interpretation of effect by people remote from the study. The primary outcome though in comparison to the aforementioned retrospective study was a short one. In this study the primary outcome was initialy absense of seizures for 48 hours but then was changed part way through the study to 24 hours. The change was a practical one since it was noted after data collection that in many cases EEG monitoring had been stopped prior to 48 hours.

The Results

Honestly it is the results that led me to want to talk about this study. They are the exact opposite of what i thought they would be. Based on my own experience with Levitiracetam seeming like a wonder drug when it comes to seizure control I expected the results to favour it. Not the case.

To say that phenobarbital crushed the competition is an udnerstatement. Having said that the incidence of side effects were higher with phenobarbital as well. Hypotension, respiratory suppression, sedation, and requirement for pressor support, were more common. Nonetheless, this study also included patients with HIE and found even in this subgroup phenobarbital was superior. This is important information as one could speculate that earlier seizure cessation in those with anoxic injury already could be especially beneficial.

What do we do with these results?

As the authors point out this is a study of short term outcomes. In the trial about long term outcome it was clear that treatment with phenobarbital leads to worse outcome than with levitiracetam. Having said that it was a retrospective study so the next step will be to conduct long term outcome studies to see effects. This presents the possibility of an interesting conundrum. What if the newer drug is inferior to tried and true phenobarbital at controlling seizures but leads to better long term outcome? Would you consider allowing seizures to persist longer than you might otherwise want to in the short term but then be able to reassure families that the long term outlook is bettter? The side effect profile of levitiracetam is such that I think neurologists want to use it but the other possibility is that there is another newer anticonvulsant that will need to be tested as wouldn’t it be great not to have to choose either poor acute seizure control but better long term outcome vs better seizure control with concerning long term outcome? As a parent I have no doubt watching a child eize would be terrifying and you would want it to end as soon as possible but the question with phenobarbital is at what cost?