When I trained here in Virchester we had a fairly aggressive approach to the management of pneumothoraces. All trauma pneumothoraces got chest drains, a chest drain meant an open one, the size was as big as possible and the analgesia was homeopathic. Looking back those were not great times for the patient, but because of the procedure paradox we did learn a lot, and arguably ‘looked forward’ to the procedures.1 In stark contrast, the patients clearly did not.
We’ve blogged in the past on the increasingly conservative management of traumatic pneumothoraces2, and in our current practice this is what we do. Small and asymptomatic traumatic pneumothoraces are now managed conservatively in our practice, but what about the patients who present with the ‘medical’ pneumothoraces? For them little has changed as we still follow the BTS guidelines3 which recommend aspiration and/or chest drains for moderate, large, secondary and symptomatic pneumothoraces. The BTS guideline is shown below.
American guidance is even more aggressive, with an approach to just go for chest drainage4.
The bottom line is that we do put quite a lot of chest drains in for medical pneumothoraces. Almost always this means a small (12F) Seldinger technique which is great for patients, but it does need an admission and quite a lot of faffing about. This of course is in contrast to the direction of travel in the management of some of our traumatic pneumothoraces. Could we be more conservative in that group as well? A recent systematic review noted that the evidence to support decision making in this situation is poor5.
This month we have a paper in the NEJM6 that may help answer that question. It’s received quite a bit of interest in the #FOAMed world already, but as it’s directly relevant to our day to day practice it’s worth a look from the St Emlyn’s team.
You can read the abstract of the NEJM paper6 below, but as we always say PLEASE read the full paper yourself and make up your own mind before changing practice.
What kind of paper is this?
This is a randomised controlled trial which is the appropriate design for an intervention, or as in this case, the lack of an intervention. This is a non-inferiority trial in. that they were trying to find out whether conservative management was non-inferior./no worse than interventions. The margin of non-inferiority that they chose was 9 percentage points. In my opinion that’s a pretty big margin (Ed – close to an NNH of 10). Clinically I would have hoped for a much smaller non-inferiority margin than one in 10 patients.
Tell me about the patients.
These were patients with spontaneous and pretty large pneumothoraces, certainly of a size that we would currently try and drain here in Virchester. Patients aged 14-50 with a pneumothorax of >32% were eligible7. Patients were recruited in 39 Antipodean emergency departments.
What did they do?
Very simply, patients were randomised to either a conservative watch and wait approach. They had another CXR at 4 hours and if that was OK, the patient was well and not distressed then they were allowed home. Many patients needed more than 4 hours of chest drain placement, but it could be removed after a minimum of 4 hours.
The intervention group had a 12F Seldinger drain just as we normally do here in Virchester. However, in this study the drain could be removed as early as 4 hours. That’s a lot sooner than we remove them here in Virchester which may be an important difference between this study and our practice.
Patients were followed up at 24 and 72 hours and then again at 2, 4, and 8 weeks.
What were the main results?
They recruited 316 patients over a 6 year period. Of the 316 patients who entered the trial 272 made it through to having had a follow up CXR at 8 weeks. In other words the drop out rate was quite high, although they had taken some account of this in their sample size calculations where a significant drop out rate had been anticipated. However, we don’t know the outcomes for those missing patients.
In terms of the primary outcome, when excluded missing patients 98.5% of the intervention group had resolved their pneumothorax in comparison to 94.4% in the conservative management group. That’s a risk difference of −4.1 percentage points; 95% confidence interval [CI], −8.6 to 0.5; P=0.02 for
non-inferiority. So in the opinion of the authors non-inferiority has not been demonstrated. However, as we mentioned above it’s quite a large inferiority margin.
In the secondary outcomes there was again a trend towards benefits to a conservative approach. Fewer days off work, fewer interventions and a lower recurrence rate as examples. These may well influence your decsion as to whether to offer conservative management. The reason for a lower recurrence rate is interesting as I can’t think of a pathophysiological mechanism for this.
Notably, no patients in the conservative management group required emergency intervention, so within this relatively small group of patients in the trial it was safe. However, this trial is too small to assure us of the safety of this approach if applied in practice.
What does this mean for our patients in Virchester?
I was hopeful that this paper would convince me that a conservative approach is the way to go, but this paper has some concerns. The drop out rate, a number of protocol violations, the large inferiority margins and the short intervention time for some patients means that I don’t think it directly answers or questions our practice in Virchester.
I’m also intrigued that it took 6 years across 39 centres to recruit this number of patients. That seems a long time across a very large service. The number of patients screened was over 2600 suggesting that this data only applies to a very small subset of patients with spontaneous pneumothoraces.
That, together with the relatively low level of intervention required by a 12F Seldinger technique, means that I think our practice will largely remain the same. However, in some patients, perhaps those who aren’t very keen to have a procedure done I do now know that a conservative approach appears to be a reasonable and probably(?) safe option. The accompanying editorial in the NEJM comes to roughly the same conclusion, similarly describing the analysis as ‘statistically fragile’.
The summary from NEJM in video is a more positive as shown below.
Update: The authors of the paper are much more positive about their own findings and I would encourage you to read their rebuttal in the comments section below. I think the question they are challenging us with is, ‘what would make you change practice, if not this paper?’. That’s a fair question (it was one of my SMACC talks in fact), and I think the answer is complicated. Offline I’ve had some great chats with Gerben Keijzers, some of which you can read in the comments section below. It’s always really interesting to hear the insider view of a trial as there is always more clarity available than from the print version in the journal.
What is very interesting is the experience post trial where they have adopted a more conservative approach, apparently with success. That data is not yet published, but should it be, then that would be very influential in changing practice.
The bottom line
Conservative management of moderate and large spontaneous pneumothoraces is an option, but we will wait for changes to the BTS guidelines before changing our regular practice.
- 1.Carley S. DFTB. The procedure paradox update. St Emlyn’s. https://www.stemlynsblog.org/how-it-felt-the-procedure-paradox-update-dftb/. Published 2020. Accessed 2020.
- 2.Carley S. Conservative management of chest trauma. St Emlyn’s. https://www.stemlynsblog.org/jc-conservative-management-of-chest-trauma-st-emlyns/. Published 2018. Accessed 2020.
- 3.MacDuff A, Arnold A, Harvey J. Management of spontaneous pneumothorax: British Thoracic Society pleural disease guideline 2010. Thorax. August 2010:ii18-ii31. doi:10.1136/thx.2010.136986
- 4.Baumann MH, Strange C, Heffner JE, et al. Management of Spontaneous Pneumothorax. Chest. February 2001:590-602. doi:10.1378/chest.119.2.590
- 5.Ashby M, Haug G, Mulcahy P, Ogden KJ, Jensen O, Walters JA. Conservative versus interventional management for primary spontaneous pneumothorax in adults. Cochrane Database of Systematic Reviews. December 2014. doi:10.1002/14651858.cd010565.pub2
- 6.Brown SGA, Ball EL, Perrin K, et al. Conservative versus Interventional Treatment for Spontaneous Pneumothorax. N Engl J Med. January 2020:405-415. doi:10.1056/nejmoa1910775
- 7.Collins CD, Lopez A, Mathie A, Wood V, Jackson JE, Roddie ME. Quantification of pneumothorax size on chest radiographs using interpleural distances: regression analysis based on volume measurements from helical CT. American Journal of Roentgenology. November 1995:1127-1130. doi:10.2214/ajr.165.5.7572489