What is old is new again as the saying goes. I continue to hope that at some point in my lifetime a “cure” will be found for BPD and is likely to centre around preventing the disease from occurring. Will it be the artificial placenta that will allow this feat to be accomplished or something else? Until that day we unfortunately are stuck with having to treat the condition once it is developing and hope that we can minimize the damage. When one thinks of treating BPD we typically think of postnatal steroids. Although the risk of adverse neurodevelopmental outcome is reduced with more modern approaches to use, such as with the DART protocol,most practitioners would prefer to avoid using them at all if possible. We know from previous research that a significant contributor to the development of BPD is inflammation. As science advanced, the specific culprits for this inflammatory cascade were identified and leukotrienes in particular were identified in tracheal lavage fluid from infants with severe lung disease. The question then arises as to whether or not one could ameliorate the risk of severe lung disease by halting at least a component of the inflammatory cascade leading to lung damage.
In our unit, we have tried using the drug monteleukast, an inhibitor of leukotrienes in several patients. With a small sample it is difficult to determine exactly whether this has had the desired effect but in general has been utilized when “all hope is lost”. The patient has severe disease already and is stuck on high frequency ventilation and may have already had a trial of postnatal steroids. It really is surprising that with the identification of leukotriene involvement over twenty years ago it took a team in 2014 to publish the only clinical paper on this topic. A German team published Leukotriene receptor blockade as a life-saving treatment in severe bronchopulmonary dysplasia.in 2014 and to date as far as I can see remains the only paper using this strategy. Given that we are all looking for ways to reduce BPD and this is the only such paper out there I thought you might want to see what they found. Would this be worth trying in your own unit? Well, read on and see what you think!
Who was included?
This study had an unusual design that will no doubt make statistical purists cringe but here is what they did. The target population for the intervention were patients with “life threatening BPD”. That is, in the opinion of the attending Neonatologist the patient had a greater than 50% likelihood of dying and also had to meet the following criteria; born at < 32 weeks GA, <1500g and had to be ventilated at 28 days. The authors sought a blinded RCT design but the Research Ethics Board refused due to the risk of the drug being low and the patients having such a high likelihood of death. The argument in essence was if the patients were likely to die and this drug might benefit them it was unethical to deny them the drug. The authors attempted to enroll all eligible patients but wound up with 11 treated and 11 controls. The controls were patients either with a contraindication to the drug or were parents who consented to be included in the study as controls but didn’t want the drug. Therapy was started for all between 28 – 45 days of age and continued for a wide range of durations (111+/-53 days in the study group). Lastly, the authors derived a score of illness severity that was used empirically:
PSC = FiO2 X support + medications
– support was equal to 2.5 for a ventilator. 1.5 for CPAP and 1 for nasal cannulae or an oxygen hood
– medications were equal to 0.2 for steroids, 0.1 for diruetics or inhaled steroids, 0.05 for methylxanthines or intermittent diruetics.
Did it make a difference?
The study was very small and each patient who received the medication was matched with one that did not receive treatment. Matching was based on GA, BW and the PSC with matching done less than 48 hours after enrollment in an attempt to match the severity of illness most importantly.
First off survival in the groups were notably different. A marked improvement in outcome was noted in the two groups. Of the deaths in the control group, the causes were all pulmonary and cardiac failure, although three patients died with a diagnosis of systemic inflammatory response syndrome. That is quite interesting given that monteleukast is an anti-inflammatory medication and none of the patients in the treatment arm experienced this diagnosis.
The second point of interest is the trend in the illness severity score over time. The time points in the figure are time 1 (start of study), time 2 (4 weeks of treatment), time 3 (end of treatment). These patients improved much more over time than the ones who did not receive treatment.
The Grain of Salt
As exciting as the results are, we need to acknowledge a couple things. The study is small and with that the risk of the results appearing to be real but in actual fact there being no effect is not minimal. As the authors knew who was receiving monteleukast it is possible that they treated the kids differently in the unit. If you believed that the medication would work or moreover wanted it to work, did you pay more attention on rounds and during a 24 hour period to those infants? Did the babies get more blood gases and tighter control of ventilation with less damage to the lungs over time? There are many reasons why these patients could have been different including earlier attempts to extubate. The fact is though the PSC scores do show that the babies indeed improved more over time so I wouldn’t write it off entirely that they did in fact benefit. The diagnosis of SIRS is a tough one to make in a newborn and I worry a little that knowing the babies didn’t receive an anti-inflammatory drug they were “given” that diagnosis.
Would I use it in spite of these faults? Yes. We have used it in such cases but I can’t say for sure that it has worked. If it does, the effect is not immediate and we are left once we start it not knowing how long to treat. As the authors here say though, the therapeutic risk is low with a possibly large benefit. I doubt it is harmful so the question we are left asking is whether it is right for you to try in your unit? As always perhaps a larger study will be done to look at this again with a blinded RCT structure as the believers won’t show up I suspect without one!
Given that today is world prematurity day it seems fitting to talk about prematurity at the absolute extreme of it.
It has been some time since as a regional program we came to accept that we would offer resuscitation to preterm infants born as early as 23 weeks gestational age. This is perhaps a little later in the game that other centers but it took time to digest the idea that the rate of intact survival was high enough to warrant a trial of resuscitation. This of course is not a unilateral decision but rather a decision arrived at after consultation with the family and interprofessional team. To be sure it is not an easy one. Other centers have argued that resuscitation should be offered to those infants as young as 22 weeks gestational age and data now exists due to enough centres doing so to provide families with some guidance as to expected survival rates and importantly the likelihood of disability. This topic has been covered previously in /2015/09/25/winnipeg-hospital-about-to-start-resuscitating-infants-at-23-weeks/. Why cover this topic again? Well an article on CNN might have something to do with it.
Resuscitating Below 22 weeks
This week as I was perusing the news I came across a rather shocking article on CNN. Born before 22 weeks, ‘most premature’ baby is now thriving. The article tells the tale of a baby delivered at 21 weeks and 4 days that now as a three year old is reaching appropriate milestones without any significant impairments. It is a story that is filled with inspiration and so I am not mistaken I am delighted for this child and their family that this outcome has occurred. When the lay press latches onto stories like this there is no doubt a great deal of sensationalism to them and in turn that gathers a lot of attention. This in turn is a great thing for media.
A Few Caveats Though
With the exception of pregnancies conceived through IVF the best dating we have is only good to about +/- 5 days when an early first trimester ultrasound is performed or the date of the last menstrual period is fairly certain. A baby though who is born at 21 weeks + 4 days may in fact be 22 +3 days or even more depending on when the dating was done (second trimester worse). Let’s not take away though from the outcome being this good even at 22 weeks. That is a pretty perfect outcome for this family but the point is that this baby may in fact be older than 21 weeks.
Secondly, there are millions of babies born each year in North America. Some of these infants are born at 22 weeks. How do they fare overall? From the paper by Rysavy et al from 2015 the results are as follows.
If you look at the overall rate of survival it is on an average of 5.1%. If you take a look though at those infants in whom resuscitation is provided that number increases to a mean of 23%. Intact survival is 9% overall. The odds aren’t great but they are there and I suspect the infant in the article is one of those babies. Flipping the argument though to the glass is half empty, 91% of infants born at 22 weeks by best estimate who are offered resuscitation will have a moderate or severe disability or die. I am not saying what one should do in this situation but depending on how a family processes the data they will either see the 110 chance of intact survival as a good thing or a 9/10 chance of death or disability as a very bad thing. What a family chooses though is anyone’s best guess.
Should we resuscitate below 22 weeks if the family wishes?
I guess in the end this really depends on a couple things. First off, how certain are the dates? If there is any degree of uncertainty then perhaps the answer is yes. If the dates are firm then I at least believe there is a barrier at which futility is reached. Perhaps this isn’t at 21 weeks as some patients may indeed be older but think about what you would offer if a family presented at 20 weeks and wanted everything done. What if it were 19 weeks? I suspect the point of futility for all lies somewhere between 19-21 weeks.
As I prepare to attend the annual meeting in Ottawa tomorrow for the Fetus and Newborn Committee I think it is prudent to point out just how difficult all of this is. The current statement on Counselling and management for anticipated extremely preterm birth I think hits on many of these issues. The statement is the product on not only the think tank that exists on this committee but was the product of a national consultation. I know I may be biased since I sit on the committee but I do believe it really hits the mark.
Should we be thinking about resuscitating at 21 weeks? For me the answer is one clouded by a whole host of variables and not one that can be easily answered here. What I do think though is that the answer in the future may be a yes provided such infants can be put onto an artificial placenta. Even getting a few more weeks of growth before aerating those lungs is necessary may make all the difference. The NICUs of tomorrow certainly may look quite different than they do now.
A patient has been extubated to CPAP and is failing with increasing oxygen requirements or increasing apnea and bradycardia. In most cases an infant would be reintubated but is there another way? While CPAP has been around for some time to support our infants after extubation, a new method using high frequency nasal ventilation has arrived and just doesn’t want to go away. Depending on your viewpoint, maybe it should or maybe it is worth a closer look. I have written about the modality before in High Frequency Nasal Ventilation: What Are We Waiting For? While it remains a promising technology questions still remain as to whether it actually delivers as promised.
Better CO2 elimination?
For those who have used a high frequency oscillator, you would know that it does a marvelous job of removing CO2 from the lungs. If it does so well when using an endotracheal tube, why wouldn’t it do just as good a job when used in a non-invasive way? That is the hypothesis that a group of German Neonatologists put forth in their paper this month entitled Non-invasive high-frequency oscillatory ventilation in preterm infants: a randomised controlled crossover trial. In this relatively small study of 26 preterm infants who were all less than 32 weeks at delivery, babies following extubation or less invasive surfactant application were randomized to either receive nHFOV then CPAP for four hours each or the reverse order for the same duration. The primary outcome here was reduction in pCO2 with the goal of seeking a difference of 5% or more in favour of nHFOV. Based on their power calculation they thought they would need 24 infants total and therefore exceeded that number in their enrollment.
The babies in both arms were a bit different which may have confounded the results. The group randomized to CPAP first were larger (mean BW 1083 vs 814g), and there was a much greater proportion of males in the CPAP group. As well, the group randomized first to CPAP had higher baseline O2 saturation of 95% compared to 92% in the nHFOV group. Lastly and perhaps most importantly, there was a much higher rate of capillary blood sampling instead of arterial in the CPAP first group (38% vs 15%). In all cases the numbers are small but when looking for such a small difference in pCO2 and the above mentioned factors tipping the scales one way or the other in terms of illness severity and accuracy of measurement it does give one reason to pause when looking at the results.
No difference was found in the mean pCO2 from the two groups. As expected, pCO2 obtained from capillary blood gases nearly met significance for being higher than arterial samples (50 vs 47; p=0.052). A similar rate of babies had to drop out of the study (3 on the nCPAP first and 2 on the nHFOV side).
In the end should we really be surprised by the results? I do believe that in the right baby who is about to fail nCPAP a trial of nHFOV may indeed work. By what means I really don’t understand. Is it the fact that the mean airway pressure is generally set higher than on nCPAP in some studies? Could it be the oscillatory vibration being a kind of noxious stimulus that prevents apneic events through irritation of the infant?
While traditional invasive HFOV does a marvelous job of clearing out CO2 I have to wonder how the presence of secretions and a nasopharynx that the oscillatory wave has to avoid (almost like a magic wave that takes a 90 degree turn and then moves down the airway) allows much of any of the wave to reach the distal alveoli. It would be similar to what we know of inhaled steroids being deposited 90 or so percent in the oral cavity and pharynx. There is just a lot of “stuff” in the way from the nostril to the alveolus.
This leads me to my conclusion that if it is pCO2 you are trying to lower, I wouldn’t expect any miracles with nHFOV. Is it totally useless? I don’t think so but for now as a respiratory modality I think for the time being it will continue to be “looking for a place to happen”
If you work in Neonatology then chances are you have ordered or assisted with obtaining many chest x-rays in your time. If you look at home many chest x-rays some of our patients get, especially the ones who are with us the longest it can be in the hundreds. I am happy to say the tide though is changing as we move more and more to using other imaging modalities such as ultrasound to replace some instances in which we would have ordered a chest x-ray. This has been covered before on this site a few times; see Point of Care Ultrasound in the NICU, Reducing Radiation Exposure in Neonates: Replacing Radiographs With Bedside Ultrasound. and Point of Care Ultrasound: Changing Practice For The Better in NICU.This post though is about something altogether different.
If you do a test then know what you will do with the result before you order it.
If there is one thing I tend to harp on with students it is to think about every test you do before you order it. If the result is positive how will this help you and if negative what does it tell you as well. In essence the question is how will this change your current management. If you really can’t think of a good answer to that question then perhaps you should spare the infant the poke or radiation exposure depending on what is being investigated. When it comes to the baby born before 30 weeks these infants are the ones with the highest risk of developing chronic lung disease. So many x-rays are done through their course in hospital but usually in response to an event such as an increase in oxygen requirements or a new tube with a position that needs to be identified. This is all reactionary but what if you could do one x-ray and take action based on the result in a prospective fashion?
In this study they looked retrospectively at 336 preterm infants weighing less than 1500g and less than 32 weeks at birth. Armed with the knowledge that many infants who have an early abnormal x-ray early in life who go on to develop BPD, this group decided to test the hypothesis that an x-ray demonstrating a pneumonia like pattern at day 7 of life predicts development of BPD. The patterns they were looking at are demonstrated in this figure from the paper. Essentially what the authors noted was that having the worst pattern of the lot predicted the development of later BPD. The odds ratio was 4.0 with a confidence interval of 1.1 – 14.4 for this marker of BPD. Moreover, birthweight below 1000g, gestational age < 28 weeks and need for invasive ventilation at 7 days were also linked to the development of the interstitial pneumonia pattern.
What do we do with such information?
I suppose the paper tells us something that we have really already known for awhile. Bad lungs early on predict bad lungs at a later date and in particular at 36 weeks giving a diagnosis of BPD. What this study adds if anything is that one can tell quite early whether they are destined to develop this condition or not. The issue then is what to do with such information. The authors suggest that by knowing the x-ray findings this early we can do something about it to perhaps modify the course. What exactly is that though? I guess it is possible that we can use steroids postnatally in this cohort and target such infants as this. I am not sure how far ahead this would get us though as if I had to guess I would say that these are the same infants that more often than not are current recipients of dexamethasone.
Would another dose of surfactant help? The evidence for late surfactant isn’t so hot itself so that isn’t likely to offer much in the way of benefit either.
In the end the truth is I am not sure if knowing concretely that a patient will develop BPD really offers much in the way of options to modify the outcome at this point. Having said that the future may well bring the use of stem cells for the treatment of BPD and that is where I think such information might truly be helpful. Perhaps a screening x-ray at 7 days might help us choose in the future which babies should receive stem cell therapy (should it be proven to work) and which should not. I am proud to say I had a chance to work with a pioneer in this field of research who may one day cure BPD. Dr. Thebaud has written many papers of the subject and if you are looking for recent review here is one Stem cell biology and regenerative medicine for neonatal lung diseases.Do I think that this one paper is going to help us eradicate BPD? I do not but one day this strategy in combination with work such as Dr. Thebaud is doing may lead us to talk about BPD at some point using phrases like “remember when we used to see bad BPD”. One can only hope.
Given that many preterm infants as they near term equivalent age are ready to go home it is common practice to discontinue caffeine sometime between 33-34 weeks PMA. We do this as we try to time the readiness for discharge in terms of feeding, to the desire to see how infants fare off caffeine. In general, most units I believe try to send babies home without caffeine so we do our best to judge the right timing in stopping this medication. After a period of 5-7 days we generally declare the infant safe to be off caffeine and then move on to other issues preventing them from going home to their families. This strategy generally works well for those infants who are born at later gestations but as Rhein LM et al demonstrated in their paper Effects of caffeine on intermittent hypoxia in infants born prematurely: a randomized clinical trial., after caffeine is stopped, the number of intermittent hypoxic (IH) events are not trivial between 35-39 weeks. Caffeine it would seem may still offer some benefit to those infants who seem otherwise ready to discontinue the medication. What the authors noted in this randomized controlled trial was that the difference caffeine made when continued past 34 weeks was limited to reducing these IH events only from 35-36 weeks but the effect didn’t last past that. Why might that have been? Well it could be that the babies after 36 weeks don’t have enough events to really show a difference or it could be that the dose of caffeine isn’t enough by that point. The latter may well be the case as the metabolism of caffeine ramps up during later gestations and changes from a half life greater than a day in the smallest infants to many hours closer to term. Maybe the caffeine just clears faster?
Follow-up Study attempts to answer that very question.
Recognizing the possibility that levels of caffeine were falling too low after 36 weeks the authors of the previous study begun anew to ask the same question but this time looking at caffeine levels in saliva to ensure that sufficient levels were obtained to demonstrate a difference in the outcome of frequency of IH. In this study, they compared the original cohort of patients who did not receive caffeine after planned discontinuation (N=53) to 27 infants who were randomized to one of two caffeine treatments once the decision to stop caffeine was made. Until 36 weeks PMA each patient was given a standard 10 mg/kg of caffeine case and then randomized to two different strategies. The two dosing strategies were 14 mg/kg of caffeine citrate (equals 7 mg/kg of caffeine base) vs 20 mg/kg (10 mg/kg caffeine base) which both started once the patient reached 36 weeks in anticipation of increased clearance. Salivary caffeine levels were measured just prior to stopping the usual dose of caffeine and then one week after starting 10 mg/kg dosing and then at 37 and 38 weeks respectively on the higher dosing. Adequate serum levels are understood to be > 20 mcg/ml and salivary and plasma concentrations have been shown to have a high level of agreement previously so salivary measurement seems like a good approach. Given that it was a small study it is work noting that the average age of the group that did not receive caffeine was 29.1 weeks compared to the caffeine groups at 27.9 weeks. This becomes important in the context of the results in that earlier gestational age patients would be expected to have more apnea which is not what was observed suggesting a beneficial effect of caffeine even at this later gestational age. Each patient was to be monitored with an oximeter until 40 weeks as per unit guidelines.
So does caffeine make a difference once term gestation is reached?
A total of 32 infants were enrolled with 12 infants receiving the 14 mg/kg and 14 the 20 mg/kg dosing. All infants irrespective of assigned group had caffeine concentrations above 20 mcg/mL ensuring that a therapeutic dose had been received. The intent had been to look at babies out to 40 weeks with pulse oximetry even when discharged but owing to drop off in compliance with monitoring for a minimum of 10 hours per PMA week the analysis was restricted to infants at 37 and 38 weeks which still meant extension past 36 weeks as had been looked at already in the previous study. The design of this study then compared infants receiving known therapeutic dosing at this GA range with a previous cohort from the last study that did not receive caffeine after clinicians had determined it was no longer needed.
The outcomes here were measured in seconds per 24 hours of intermittent hypoxia (An IH event was defined as a decrease in SaO2 by ⩾ 10% from baseline and lasting for ⩾5 s). For graphical purposes the authors chose to display the number of seconds oxygen saturation fell below 90% per day and grouped the two caffeine patients together given that the salivary levels in both were therapeutic. As shown a significant difference in events was seen at all gestational ages.
Putting it into context
The scale used I find interesting and I can’t help but wonder if it was done intentionally to provide impact. The outcome here is measured in seconds and when you are speaking about a mean of 1200 vs 600 seconds it sounds very dramatic but changing that into minutes you are talking about 20 vs 10 minutes a day. Even allowing for the interquartile ranges it really is not more than 50 minutes of saturation less than 90% at 36 weeks. The difference of course as you increase in gestation becomes less as well. When looking at the amount of time spent under 80% for the groups at the three different gestational ages there is still a difference but the amount of time at 36, 37 and 38 weeks was 229, 118 and 84 seconds respectively without caffeine (about 4, 2 and 1 minute per day respectively) vs 83, 41, and 22 seconds in the caffeine groups. I can’t help but think this is a case of statistical significance with questionable clinical significance. The authors don’t indicate that any patients were readmitted with “blue spells” who were being monitored at home which then leaves the sole question in my mind being “Do these brief periods of hypoxemia matter?” In the absence of a long-term follow-up study I would have to say I don’t know but while I have always been a fan of caffeine I am just not sure.
Should we be in a rush to stop caffeine? Well, given that the long term results of the CAP study suggest the drug is safe in the preterm population I would suggest there is no reason to be concerned about continuing caffeine a little longer. If the goal is getting patients home and discharging on caffeine is something you are comfortable with then continuing past 35 weeks is something that may have clinical impact. At the very least I remain comfortable in my own practice of not being in a rush to stop this medication and on occasion sending a patient home with it as well.
We can always learn and we can always do better. At least that is something that I believe in. In our approach to resuscitating newborns one simple rule is clear. Fluid must be replaced by air after birth and the way to oxygenate and remove CO2 is to establish a functional residual capacity. The functional residual capacity is the volume of air left in the lung after a tidal volume of air is expelled in a spontaneously breathing infant and is shown in the figure. Traditionally, to establish this volume in a newborn who is apneic, you begin PPV or in the spontaneously breathing baby with respiratory distress provide CPAP to help inflate the lungs and establish FRC.
Is there another way?
Something that has been discussed now for some time and was commented on in the most recent version of NRP was the concept of using sustained inflation (SI) to achieve FRC. I have written about this topic previously and came to a conclusion that it wasn’t quite ready for prime time yet in the piece Is It Time To Use Sustained Lung Inflation In NRP?
The conclusion as well in the NRP textbook was the following:
“There are insufficient data regarding short and long-term safety and the most appropriate duration and pressure of inflation to support routine application of sustained inflation of greater than 5 seconds’ duration to the transitioning newborn (Class IIb, LOE B-R). Further studies using carefully designed protocols are needed”
So what now could be causing me to revisit this concept? I will be frank and admit that whenever I see research out of my old unit in Edmonton I feel compelled to read it and this time was no different. The Edmonton group continues to do wonderful work in the area of resuscitation and expand the body of literature in such areas as sustained inflation.
Can you predict how much of a sustained inflation is needed?
This is the crux of a recent study using end tidal CO2 measurement to determine whether the lung has indeed established an FRC or not. Dr. Schmolzer’s group in their paper (Using exhaled CO2 to guide initial respiratory support at birth: a randomised controlled trial) used end tidal CO2 levels above 20 mmHg to indicate that FRC had been established. If you have less CO2 being released the concept would be that the lung is actually not open. There are some important numbers in this study that need to be acknowledged. The first is the population that they looked at which were infants under 32 6/7 weeks and the second is the incidence of BPD (need for O2 or respiratory support at 36 weeks) which in their unit was 49%. This is a BIG number as in comparison for infants under 1500g our own local incidence is about 11%. If you were to add larger infants closer to 33 weeks our number would be lower due to dilution. With such a large number though in Edmonton it allowed them to shoot for a 40% reduction in BPD (50% down to 30%). To accomplish this they needed 93 infants in each group to show a difference this big.
So what did they do?
For this study they divided the groups in two when the infant wouldn’t breathe in the delivery room. The SI group received a PIP of 24 using a T-piece resuscitator for an initial 20 seconds. If the pCO2 as measured by the ETCO2 remained less than 20 they received an additional 10 seconds of SI. In the PPV group after 30 seconds of PPV the infants received an increase of PIP if pCO2 remained below 20 or a decrease in PIP if above 20. In both arms after this phase of the study NRP was then followed as per usual guidelines.
The results though just didn’t come through for the primary outcome although ventilation did show a difference.
Duration of mechanical ventilation (hrs)
The reduction in hours of ventilation was impressive although no difference in BPD was seen. The problem though with all of this is what happened after recruitment into the study. Although they started with many more patients than they needed, by the end they had only 76 in the SI group and 86 in the PPV group. Why is this a problem? If you have less patients than you needed based on the power calculation then you actually didn’t have enough patients enrolled to show a difference. The additional compounding fact here is that of the Hawthorne Effect. Simply put, patients who are in a study tend to do better by being in a study. The observed rate of BPD was 33% during the study. If the observed rate is lower than expected when the power calculation was done it means that the number needed to show a difference was even larger than the amount they originally thought was needed. In the end they just didn’t have the numbers to show a difference so there isn’t much to conclude.
What I do like though
I have a feeling or a hunch that with a larger sample size there could be something here. Using end tidal pCO2 to determine if the lung is open is in and of itself I believe a strategy to consider whether giving PPV or one day SI. We already use colorimetric devices to determine ETT placement but using a quantitative measure to ascertain the extent of open lung seems promising to me. I for one look forward to the continued work of the Neonatal Resuscitation–Stabilization–Triage team (RST team) and congratulate them on the great work that they continue doing.