Posted by Matthew Mac Partlin on Wednesday, August 10, 2016 Under: Clinical topics
There have been a number of incidents at motorsport events that have resulted in a blunt chest injury mechanism with the competitor presenting to the event medical centre for assessment and while no major injuries were found they have subsequently been diagnosed with a pneumothorax. Usually it has been a small one, associated with one or more fractured ribs, diagnosed on a CT. Some of the more high profile incidents include:
- Fernando Alonso's horrifying rollover at the Melbourne F1GP where having been cleared of significant injury at the circuit medical centre, he later had a CT which showed a single rib fracture and a tiny associated pnuemothorax.
- A WRC competitor at the 2015 Rally Australia event was referred to the nearby hospital from the service park medical centre following a collision during recce and was found to have several rib fractures and again a very small pneumothorax.
- James Courtney was struck in the chest by a large placard while standing in the pit lane watching a military helicopter display and again a CT performed at the referral hospital demonstrated a few cracked ribs and a small pneumothorax.
The CT has usually been performed at a hospital later in the day, either as a result of a referral from the circuit medical centre or after a follow up check by a team or series doctor for ongoing chest wall pain. The rib fractures have often been suspected on clinical examination and in the absence of any associated significant injury or physiological derrangement, have been managed appropriately with basic analgesia and follow up advice.
But what about the pneumothorax?
If it is a large one, that's easy. An intercostal catheter goes in. Pneumothorax sorted!
If it is relatively small, as would be reasonably common practice, the pneumothorax is left to resolve by itself, with or without supplementary oxygen and with appropriate follow up. Again, job done!
However, Australia is a big country and most people get between major cities by flying. And this includes race car competitors. International competitors attend races in Australia too.
So a question that often comes up is "Can I get on my flight tomorrow?"
This seems to be a bit of a wooly area. The response from most authorities seems to be to defer flight until two weeks after the resolution of the pneumothorax, whether spontaneously or by chest drain. But that could mean a total of up to three weeks which is inconvenient, potentially expensive and may result in missing out on the next scheduled competition. So what to do? And where do the numbers come from?
Here's the problem. According to Boyle's Law a gas volume will increase as the surrounding pressure decreases. As a plane ascends, the cabin pressure drops and the fear is that a small pneumothorax will become a bigger one causing clinical decompensation. However, don't panic just yet. All commercial passenger jets have cabin pressures maintained at between 1,200 and 2,500m, depending upon their actual cruising altitude. So when you do the calculations it falls out that a volume of gas will increase by about 20-30%. If the pneumothorax has been adequately drained or was too small to be worth placing a drain to begin with, then that 20-30% increase is unlikely to result in a volume increase that is going to cause any problems; especially if the person's lungs and chest are otherwise normal.
Chartered helicopters don't fly much above 2,500m. Unfortunately I haven't had the chance to travel on any private jets, so I'm a bit unsure about these but I think if it is a jet rather than a propellor-driven plane (e.g. Cessna) the cabin is still pressurized.
A trial in 1999 by Cheatham and Safczak showed no respiratory symptom deterioration in 10 of 12 patients flying commercially more than 14 days after CXR resolution of a motor vehicle collision (MVC) associated pneumothorax. One of the two patients who flew earlier than 14 days after resolution experienced respiratory symptoms that were attributed to recurrence of a pneumothorax. That's an n=12 study! And it used a chest x-ray (CXR) to determine pneumothorax resolution, an imaging modality with known false positive and negative issues that can miss up to 30% of pneumothoraces depending upon their size, the image taken and the patient's position. If you really want to exclude a pneumothorax you should probably be using a CT (radiation lifetime risk and expense) or chest ultrasound (bedside, no radiation, and good sensitivity and sepcificity numbers)
An interesting paper by Sacco and Calero in 2014 looked at 80 trauma patients who had either a pneumothorax not requiring a chest drain, a pneumothorax drained by intercostal catheter or a haemothorax requiring a chest drain at their hospital in Anchorage who were all due to fly out subsequently. All of the patients had either a clearance CXR prior to hospital discharge or a follow up CXR within 48 hours of discharge. The age range was 2 to 60 years old (mean 32yo) and most were male. The mean delay to flight after discharge was 6 days and for the 10 patients with a known residual small pneumothorax it ranged from 0 to 15 days with all but one patient flying within 9 days. Not one complication was reported for any of these patients, including the 5 patients who's small pneumothoraces were diagnosed on CT only. The authors appropriately acknowledge the limitations of this single centre study and that this went against the aeronautical agencies guidelines of the time.
The 2011 British Thoracic Society (BTS) Guidelines recommend that patients with a spontaneous pneumothorax defer flight until at least 7 days after CXR-confirmed pneumothorax resolution. For patients with a traumatic pneumothorax a deferral of 2 weeks is recommended. It seems that the Cheatham and Safczak paper form at least part of the evidence base for these recommendations.
It also seems that the majority of world aviation agencies take their cue on commercial passenger transport from the BTS guidelines and apply the same recommendations. Here are some examples:
- Aerospace Medical Association (ASMA) guidelines
- UK Civil Aviation Authority (CAA) guidelines
- The Australian Civil Aviation Safety Authority (CASA) doesn't specify but seems to refer passengers to the individual airline for guidance
- The closest that the International Air Transport Association (IATA) guidelines get to a recommendation is Section 6.1.2(e), suggesting that medical clearance should be sought where a patient "has a medical condition which may be adversely affected by the flight environment".
As an example of a specific airline's guidelines, the Qantas Group Medical Travel Clearance Guidelines state that a person is "not suitable to fly for 7 days or less after full lung expansion" and a Travel Clearance Form completed by a doctor is required for commercial passenger flight "within 8 - 21 days after full lung expansion".
So it would seem that the actual risk of significant decompensation from a small, undrained traumatic pneumothorax in the absence of associated significant injury with a CXR demonstrating resolution is miniscule. It would further seem that a small pneumothorax detected only on CT would be of similar low risk, though this represents only 5 of the patients in the Alaskan paper. And there is no evidence for what to do with the ultrasound detected pneumothorax, though one could extrapolate to requesting a follow-up CXR or CT. However, the established guidelines for commercial passenger air travel continue to recommend a 2 week post resolution by CXR deferal.
Now what is your answer to the competitor?
So, within minutes of publishing this post, the omni-present Dr Minh Le Cong (@ketaminh) got stuck into me on Twitter. His comments were completely fair, so I'm posting up our conversation below. So of it is a little out of sequence because of how Twitter collates conversation replies, but you'll get the gist of it.
References and Resources
- Flying After Pneumothorax on The Trauma Professional's Blog - http://regionstraumapro.com/post/1156057830/flightptx
- Cheatham ML, Safcsak K. Air travel following traumatic pneumothorax: when is it safe? Am Surg 1999; 65:1160–1164 - http://www.ncbi.nlm.nih.gov/pubmed/10597066
- The Accuracy of Plain Radiography in Detection of Traumatic Intrathoracic Injuries. Maryam Abedi Khorasgani et al. The Journal of Emergency. 2016 (4) - http://journals.sbmu.ac.ir/emergency/article/view/10123
- Diagnostic Accuracy of Chest Ultrasonography versus Chest Radiography for Identification of Pneumothorax: A Systematic Review and Meta-Analysis. Ali Ebrahimi et al. Tanaffos. 2014; (4): 29–40. PMCID: PMC438601313 - http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4386013/
- Is thoracic ultrasound a viable alternative to conventional imaging in the critical care setting? D. T. Ashton-Cleary. Br J Anaesth. 2013. - http://bja.oxfordjournals.org/content/early/2013/04/12/bja.aet076.full
- Safety of early air travel after treatment of traumatic pneumothorax. Frank Sacco and Kelly R. Calero. Int J Circumpolar Health. 2014; 73. PMCID: PMC3984405 - http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3984405/
In : Clinical topics
Tags: "pneumothorax" "flight after pneumothorax"
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