I didn’t post much about last year’s PAS (and I am not sure I will have the energy in future years either) there are often disappointments and surprises, abstrracts presented as platforms in important sessions that should not have been, and others that should have been given a platform that were hidden in a corner of a poster session. Organizing a huge conference like PAS, there are bound to be missteps like that, some of which are just differences of opinion, some of which everyone agrees to. Last year there was a really important, simple, randomized clinical trial that didn’t get the forum it deserved. But it has now been published in full, and it is a gem. Murphy MC, et al. Effect of needle aspiration of pneumothorax on subsequent chest drain insertion in newborns: A randomized clinical trial. JAMA Pediatrics. 2018.
Colm O’Donnell has a gift for asking simple clinical questions that can have big impact on practice. For example “can we really tell if a baby is hypoxic by looking at their colour?” The answer is clearly no, which is why we now place pulse oximeter probes as soon as we can during resuscitation.
This study was designed to ask another simple clinical question that has not been asked (or at least not answered) previously. “If a baby has a pneumothorax that appears to be symptomatic, do they need a chest tube, or can just draining it with a needle be enough?”
I was brought up in an era of neonatology (pre-surfactant) where inserting chest tubes was a nightly occurrence. We put chest drains in at least 25% of our ventilated babies, and often had to put tubes in both sides.
When I arrived in Edmonton as a fellow, the practice was to put a prophylactic chest tube in the contralateral side whenever we had a unilateral pneumothorax, because the incidence of contralateral pneumothoraces was so high, and the acute hemodynamic and ventilatory consequences of a pneumothorax were dramatic. So the thought was that you were better to prophylactically drain the other pleural space before it happened.
My co-fellow, Tony Ryan, and I studied all of our cases, and it was clear that if you had a pneumothorax on one side and if you also had Interstitial Emphysema (PIE) on x-ray, then the majority of babies did indeed develop a pneumothorax on the other side. For those babies who did not have PIE many of them never had a second pneumothorax, so we were able to avoid contralateral drains in those babies without radiologically evident PIE.
Since then, life has changed, for the better. Few ventilated babies now develop pneumothoraces, and the nights of putting multiple chest tubes in the same baby are a distant bad memory (I did get rather good at it though!).
In the new NORD trial the investigators from a multicenter group of NICUs randomized 70 babies with a radiologically confirmed pneumothorax if they had respiratory distress (intubated, CPAP or more than 40% O2). The study was performed with a delayed consent procedure, and infants either had drainage conventionally with an intercostal drain or needle aspiration as a one time only procedure, followed by waiting to see if they needed a chest drain.
It was my usual practice to insert a drain except in the most unstable babies for whom a needle aspiration might be performed first, usually followed immediately by a chest tube. In this trial, there were 33 infants randomized to needle aspiration 18 of them needed a chest tube within the next 6 hours, and 23/33 needed one at some time during hospitalization, presumably within the next few days. Which means that quite a lot of needled babies avoided having a chest tube, which I think is a significant benefit to them.
I wonder if, based on my previous experience, babies that had PIE visible on the chest x-ray would be more likely to need a chest tube. If you could predict which babies were most likely to need a later chest tube, maybe you could select them to have an immediate chest drain after needle aspiration. In the mean time based on this trial, needle aspiration of pneumothoraces should be the usual first procedure, if a baby stabilizes after needle aspiration we can just wait and see what happens.
After reading and reviewing this article I have another alternative interpretation of the results that might have a different clinical implication. To begin with, I, like you, feel that avoiding a chest tube would be a great thing and any literature supporting this concept would be welcomed. However, I don’t think that this article as it is written really supports its conclusion that needle aspiration “should be used as the initial method…in symptomatic infants.”
First off, the study design has its inherent weaknesses, that understandably can not be avoided. Any study where the primary outcome is the same as one of the arms of the study is always hard to pragmatically interpret. With the “control” arm (i.e. chest tube) having a guaranteed 100% prevalence of the primary outcome, it doesn’t take many “avoided chest tubes” to create a statistically significant difference.
However, more concerning is the interpretation of the results. At first glance it may appear (as the authors lead to reader to infer) that 45% and 30% of infants avoided chest tube placement within the first 6 hours or hospitalization, respectively. I may suggest that conversely 55% and 70% of infants “failed” needle aspiration and where exposed to a prolonged (or even a repeated) pneumothorax with its associated hemodynamic compromise. Looking deeper into the data we can see that 12/17 (71%) of infants
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Looking deeper into the data we can see that 12/17 (71%) of infants <32 weeks (the most vulnerable population) needed a chest tube within 6 hours. So pragmatically speaking, ~70% of the most vulnerable infants spent a prolonged amount a time with a hemodynamically significant pneumothorax that needed more aggressive treatment to relive its untoward effects. I wonder how much "unnecessary", or probably more correctly, "unwanted" systemic hypotension, cerebral venous hypertension and its end organ effects occurred during this critical time.
The authors do not present any data on such outcomes as IVH or PVL between the groups in this study. I would be very curious to see these results and wonder if there are significant findings worth reviewing. However, buried at the bottom of Table 3 are concerning mortality statistics. Mortality in the needle aspiration group was 21% compared to 5% in the chest tube group. Even though these numbers do not reach statistical significance (obviously secondary due to the small sample size), I find an intervention with such a large discrepancy in mortality a clinically significant outcome that gives me pause.
Without more information regarding these deaths and other important outcomes noted above I would be hesitant to suggest so definitely that needle aspiration should be the preferred method of treatment in the most small and vulnerable infants. Although avoiding invasive procedures is always the best course of action when at all possible, I just doubt that the data from this study really suggests that this the case in this scenario.
I always think needle aspiration restores some stability quickly, even if you then go on to insert a formal chest drain