Without evidence of benefit, an intervention should not be presumed to be beneficial or safe.

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Will spontaneous pneumothorax progress to tension pneumothorax?

ResearchBlogging.org

This paper gets right to the point.

Spontaneous pneumothorax must rank high in the list of common medical conditions where conventional teaching and management either make no physiological sense or are based on inadequate evidence and trials which have failed to address the most important points.[1]

make(s) no physiological sense?

based on inadequate evidence?

based on . . . trials which have failed to address the most important points?

What does he say in the rest of the paper?

Textbooks and guidelines are unanimous in attributing the mechanism of tension pneumothorax to ‘the operation of a one-way valve system, drawing air into the pleural space during inspiration not allowing it out during expiration’.1 [1]

If the conventional teaching were true, then why do so few spontaneous pneumothoraces progress to tension pneumothoraces?

Why is tension pneumothorax is rare.

Treatment of presumed tension pneumothorax appears to be much more common than tension pneumothorax.[2]


Click on the image to make it larger.

The chart is for all pneumothoraces (not just spontaneous pneumothoraces) treated as tension pneumothoraces, even if there really was no pneumothorax, but this suggests just how easily we can find what we are looking for, even when it is not there.

Did any patient have a tension pneumothorax?

We do not know.

Tension pneumothorax can only occur by generation of supra atmospheric pressures within the chest – either through positive pressure ventilation (invasive or non-invasive) or through forced expiratory manoeuvres, commonly coughing.[1]

That is not what I was taught.

A couple of studies in 1966 had conflicting results. One suggested aggressive treatment, but had no conservative treatment arm, so this was based on assuming that aggressive treatment is the best treatment. The other study showed that patients did dramatically better with conservative treatment, but almost everybody ignored that study in favor of the fatally flawed study.

In 1993 the British Thoracic Society carried out the first randomized controlled trial of treatment of spontaneous pneumothorax but unfortunately in this, as in all succeeding trials, there was no arm of conservative management with observation.12 [1]

One of our problems is the tendency toward the unproven treatment, while ignoring the possibility that lack of intervention may be a better treatment.

In cardiac arrest, we only have two interventions that have been demonstrated to improve outcomes – chest compressions and defibrillation.

A sensible approach to finding out what works would be to add only one intervention at a time and compare it with these treatments. However, even the current ROC (Resuscitation Outcomes Consortium) trials are biased by not including a treatment arm limited to treatments that have been demonstrated to improve outcomes. The proponents of the treatments that are being studied will always be able to use the excuse that these studies were biased by including treatments that do not work. Treatments that will probably be demonstrated to worsen outcomes, if we ever start following ethical research practices.

In spite of an absence of good evidence supporting aggressive treatment, the Standard Of Care has been aggressive treatment.

As we should be accustomed to by now, the Standard Of Care was based on very biased research that ignored the scientific method and put patients at risk for no real benefit.

What then is the case for doing nothing in spontaneous pneumothorax? First, the risk of death is extremely low. British figures from 1991 to 1995 show hospital admission rates for pneumothorax at 16.7/100 000 per annum,1 whereas deaths from pneumothorax (including all high risk cases) were less than 1% of this figure at 1.26/1 000 000 per annum.[1]

One in a million?

Either the aggressive treatment made a huge difference in saving lives or there was not a need for aggressive treatment to begin with.

Would it be unethical to find out if conservative treatment works?

In Cairns we have had a policy of non-intervention wherever possible for 15 years. Even with large pneumothoraces, symptoms resolve to a low level by the following day following adequate analgesia and although the patients may be breathless on moderate to vigorous exertion, they are fully capable of carrying out their daily activities and returning to work, confirming Stradling and Poole’s observations in the 1960s.10 [1]

Would many patients make an informed decision to have an invasive treatment that would lead to extended hospitalization, rather than conservative treatment?

In fact, all of the current experts in the field seem to concentrate on treating the chest X-ray appearance rather than the patient.[1]

Treat the patient, not the machine.

When will we learn?

In cardiac arrest, many of the current experts focus on obtaining ROSC (Return Of Spontaneous Circulation), while ignoring the lack of improvement in neurologically intact survival with this focus on ROSC.

But at least some of what we were taught must be true!

What causes pneumothorax? Traditionally, blebs and bullae (emphysema-like changes or ELCs) have been blamed. Smoking is in fact the predominant risk factor with a lifetime risk in male smokers estimated at 12% compared with 0.1% for lifelong non-smokers.21 [1]

Even the blebs, the mean old blebs, are not the cause. What next, no Santa Claus?

But if there is a recurrence, that is proof that the patient should have had aggressive treatment!

The risk of recurrence after a first primary spontaneous pneumothorax is estimated between 30% and 50%, smoking markedly increasing the risk.1 Once there has been one recurrence, the risk of further recurrence rises exponentially and it is certainly sensible to recommend some procedure to prevent further recurrences after the second pneumothorax on the same side. However, as primary spontaneous pneumothorax is essentially a nuisance rather than a dangerous condition it may not be necessary to go to heroic measures to prevent a recurrence which will also be merely a nuisance.[1]

This would ordinarily be a nuisance, easily managed with pain medicine, but we prefer to stick a large catheter in your chest and sometimes leave the trochar in the catheter leading to fatal outcomes. 😳

What is crucially needed here is what should have been done 40 years ago, which is a randomized controlled study of conservative observational management of primary spontaneous pneumothorax against what is currently the best evidenced intervention which is pleural aspiration.[1]

The same is true for the various superstition-based treatments that are Standards Of Care for cardiac arrest.

Maybe, someday we will learn.

Footnotes:

[1] Spontaneous pneumothorax: time for some fresh air.
Simpson G.
Intern Med J. 2010 Mar;40(3):231-4. Review.
PMID: 20446970 [PubMed – indexed for MEDLINE]

[2] When Should EMS Use Needle Decompression
Rogue Medic
Thu, 10 Nov 2011
Article

Inadequate needle thoracostomy rate in the prehospital setting for presumed pneumothorax: an ultrasound study – Full paper
Rogue Medic
Mon, 14 Feb 2011
Article

Inadequate needle thoracostomy rate in the prehospital setting for presumed pneumothorax: an ultrasound study – abstract
Rogue Medic
Tue, 07 Sep 2010
Article

Simpson, G. (2010). Spontaneous pneumothorax: time for some fresh air Internal Medicine Journal, 40 (3), 231-234 DOI: 10.1111/j.1445-5994.2009.02155.x

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