by All Things Neonatal | Sep 7, 2017 | preemie, Prematurity, ventilation
A grenade was thrown this week with the publication of the Australian experience comparing three epochs of 1991-92, 1997 and 2005 in terms of long term respiratory outcomes. The paper was published in the prestigious New England Journal of Medicine; Ventilation in Extremely Preterm Infants and Respiratory Function at 8 Years. This journal alone gives “street cred” to any publication and it didn’t take long for other news agencies to notice such as Med Page Today. The claim of the paper is that the modern cohort has fared worse in the long run. This has got to be alarming for anyone reading this! As the authors point out, over the years that are being compared rates of antenatal steroid use increased, surfactant was introduced and its use became more widespread and a trend to using non-invasive ventilation began. All of these things have been associated with better short term outcomes. Another trend was declining use of post-natal steroids after 2001 when alarms were raised about the potential harm of administering such treatments.
Where then does this leave us?
I suppose the first thing to do is to look at the study and see if they were on the mark. To evaluate lung function the study looked at markers of obstructive lung disease at 8 years of age in survivors from these time periods. All babies recruited were born between 22-27 completed weeks so were clearly at risk of long term injury. Measurements included FEV1, FVC, FVC:FEV1 and FEF 25-75%. Of the babies measured the only two significant findings were in the FEV1 and ratio of FEV1:FVC. The former showed a drop off comparing 1997 to 2005 while the latter was worse in 2005 than both epochs.
| Variable |
1991-92 |
1997 |
2005 |
| %predicted value |
N=183 |
N=112 |
N=123 |
| FEV1 |
87.9+/-13.4 |
92.0+/-15.7 |
85.4+/-14.4 |
| FEV1:FVC |
98.3+/-10 |
96.8+/-10.1 |
93.4+/-9.2 |
This should indeed cause alarm. Babies born in a later period when we thought that we were doing the right things fared worse. The authors wonder if perhaps a strategy of using more CPAP may be a possible issue. Could the avoidance of intubation and dependence on CPAP for longer periods actually contribute to injury in some way? An alternative explanation might be that the use of continuous oximetry is to blame. Might the use of nasal cannulae with temporary rises in O2 expose the infant to oxygen toxicity?
There may be a problem here though
Despite everyone’s best efforts survival and/or BPD as an outcome has not changed much over the years. That might be due to a shift from more children dying to more children living with BPD. Certainly in our own centre we have seen changes in BPD at 36 weeks over time and I suspect other centres have as well. With concerted efforts many centres report better survival of the smallest infants and with that they may survive with BPD. The other significant factor here is after the extreme fear of the early 2000s, use of postnatal steroids fell off substantially. This study was no different in that comparing the epochs, postnatal glucocorticoid use fell from 40 and 46% to 23%. One can’t ignore the possibility that the sickest of the infants in the 2005 cohort would have spent much more time on the ventilator that their earlier counterparts and this could have an impact on the long term lung function.
Another question that I don’t think was answered in the paper is the distribution of babies at each gestational age. Although all babies were born between 22-27 weeks gestational age, do we know if there was a skewing of babies who survived to more of the earlier gestations as more survived? We know that in the survivors the GA was not different so that is reassuring but did the sickest possible die more frequently leaving healthier kids in the early cohorts?
This bigger issue interestingly is not mentioned in the paper. Looking at the original cohorts there were 438 in the first two year cohort of which 203 died yielding a survival of 54% while in 1997 survival increased to 70% and in 2005 it was 65%. I can’t help but wonder if the drop in survival may have reflected a few more babies at less than 24 weeks being born and in addition the holding of post natal steroids leading to a few more deaths. Either way, there are enough questions about the cohorts not really being the same that I think we have to take the conclusions of this paper with a grain of salt.
It is a sensational suggestion and one that I think may garner some press indeed. I for one believe strongly though as I see our rates of BPD falling with the strategies we are using that when my patients return at 8 years for a visit they will be better off due to the strategies we are using in the current era. Having said that we do have so much more to learn and I look forward to better outcomes with time!
by All Things Neonatal | Feb 15, 2017 | car seat testing, Neonatal, Neonatology, neurology
The infant car seat challenge(ICSC) is a test which most definitely fits the definition of a battleground issue in Neonatology. After publishing the Canadian Pediatric Practice point on the same topic I received interesting feedback through the various social media forums that I frequent. While some were celebrating the consensus of the statement as verification that a centres’ non practice of the test was acceptable, others seriously questioned the validity of the position. The naysayers would point out that extremely infrequent events unless intentionally tracked may be difficult to pick up. In the case of the ICSC, if a few patients were to suffer a hypoxic event leading to an ALTE or worse after discharge, could the ICSC have picked out these babies and prevented the outcome? The evidence for adverse events associated with the use of car seats as discussed in the position statement is poor when using autopsy records over decades but when many clinicians can point to a failed ICSC picking up events, the thought goes that they “caught one”. Does catching one make a difference though?
The Well Appearing Infant
Shah et al in their recent paper Clinical Outcomes Associated with a Failed Infant Car Seat Challenge attempt to address this very point. They performed a retrospective study of 148 patients who were either <37 weeks GA or < 2500g at birth. The study was made possible by the fact that all such infants in their hospital admitted to a well newborn area meeting these criteria by policy must have an ICSC prior to discharge. Keep in mind that these were all infants who were on the well newborn service since they were asymptomatic. The definition of an event in this group was one or more of pulse oximeter saturation ≤ 85% for > 10 seconds, apnea > 20 seconds, bradycardia < 80 bpm for > 10 seconds, or an apnea or bradycardia event requiring stimulation. The failure rate was 4.5% which is very similar to other reported studies.
Why did they “fail”?
- Failure of the ICSC was owing to desaturation 59%
- Bradycardia 37%
- Tachypnea 4%
- Combination of 2 in 11%
What is interesting about these results is what happened to these infants after admission to the NICU in that 39% were identified with apnea (48% in preterm vs 17% in term infants). These events were in the supine position which is a curious finding since the ICSC was designed to find risk of cardiorespiratory stability in a semi-recumbent position. This has been shown previously though.
What does it all mean?
The infants in this study ultimately had more NG feeding, prolonged length of stay and septic workups after failing the ICSC that comparable infants who passed. At first blush one would read this article and immediately question the validity of the CPS position but then the real question is what has this added to the “pool of knowledge”. That infants may fail an ICSC at a rate of 4.5% is already known. That such infants may demonstrate apneic events has also been shown before and a study like this may help to support those clinicians who feel it is still imperative to find these infants in order to achieve a safe discharge. I think it is important to put these findings in the context of what would have happened if such a unit did not routinely test these types of babies. As all were seemingly well and I presume feeding with their families, they would have been discharged after 24-48 hours to home. We have no evidence (since they have not compared this sample to a group who did not have such testing) that if these babies were discharged they would have faired poorly.
The supporters of the ICSC would point to all the support these babies received by admitting them for 6-8 days, providing NG feeding and ruling out sepsis that they were unsafe for discharge. The other possible way to look at it was that the infants were subjected to interventions that we have no evidence helped them. Whether any of these infants had a positive blood culture justifying antibiotics or needed methylxanthine support is not mentioned. Judging however by the short length of stay I suspect that none or few of these infants needed such medication as I would expect they would have stayed much longer had they needed medical treatment for apnea.
Conclusion
I do commend the authors for completing the study and while it does raise some eyebrows, I don’t see it changing at least my position on the ICSC. While they have described a cohort of patients who failed the ICSC nicely, the fundamental question has been left unanswered. Does any of this matter? If you look well, are feeding well and free of any clinically recognizable events but are late preterm or IUGR can the ICSC prevent harm? This has not been answered here and perhaps the next step would be for a centre that has abandoned the ICSC to follow their patients after discharge prospectively and see whether any adverse outcomes do indeed occur. Any takers?
