All posts by TheTraumaPro

Flying Or Diving After Traumatic Pneumothorax

Patients who have sustained a traumatic pneumothorax occasionally ask how soon they can fly in an airplane or scuba dive after they are discharged. What’s the right answer?

The basic problem has to do with Boyle’s Law (remember that from high school?). The volume of a gas varies inversely with the barometric pressure. So the lower the pressure, the larger a volume of gas becomes. Most of us hang out pretty close to sea level, so this is not an issue. But for flyers or divers, it may be.

Flying

Helicopters typically fly only one to two thousand feet above the ground, so the air pressure is about the same as standing on the earth. However, flying in a commercial airliner is different. Even though the aircraft may cruise at 30,000+ feet, the inside of the cabin remains considerably lower though not at sea level. Typically, the cabin altitude goes up to about 8,000 to 9,000 feet. Using Boyle’s law, any volume of gas (say, a pneumothorax in your chest), will increase by about a third on a commercial flight.

The physiologic effect of this increase depends upon the patient. If they are young and fit, they may never know anything is happening. But if they are elderly and/or have a limited pulmonary reserve, it may compromise enough lung function to make them symptomatic. And having a medical problem in an aluminum tube at 30,000 feet is never good.

Commercial guidelines for travel after pneumothorax range from 2-6 weeks. The Aerospace Medical Association published guidelines that state that 2-3 weeks is acceptable. The Orlando Regional Medical Center reviewed the literature and devised a practice guideline that has a single Level 2 recommendation that commercial air travel is safe 2 weeks after resolution of the pneumothorax, and that a chest x-ray should be obtained immediately prior to travel to confirm resolution.

Diving

Diving would seem to be pretty safe, right? Any pneumothorax would just shrink while the diver was at depth, then re-expand to the original size when he or she surfaces, right?

Not so fast. You are forgetting why the pneumothorax was there in the first place. The lung was injured, most likely via tearing it, penetration by something sharp, or popping a bleb. If the injured area has not completely healed, then air may begin to escape through it again. And since the air used in scuba diving is delivered under pressure, this could result in a tension pneumothorax.  This is disastrous underwater!

Most injuries leading to pneumothorax heal completely. However, if there are bone spicules stuck in the lung or more complicated parenchymal injuries from penetrating injury, they may never completely heal. This makes the diver susceptible to a tension pneumothorax anytime they use their regulator.

Bottom line: Most patients can safely travel on commercial aircraft 2 weeks after resolution of pneumothorax. Ideally, a chest xray should be obtained shortly before travel to confirm that it is gone. Helicopter travel is okay at any time, since they typically fly at 1,500 feet or less.

Divers should see a physician trained in dive medicine to evaluate their injury and imaging prior to making another dive.

References:

  • Divers Alert Network – Pneumothorax – click to download
  • Practice Guideline, Orlando Regional Medical Center. Air travel following traumatic pneumothorax. October 2009.
  • Medical Guidelines for Airline Travel, 2nd edition. Aerospace Medical Association. Aviation, Space, and Environmental Medicine 74(5) Section II Supplement, May 2003.

When To Remove a Chest Tube

Chest tubes are needed occasionally to help manage chest injuries. How do you decide when they are ready for removal?

Unfortunately, the literature is not very helpful in answering this question. To come up with a uniform way of pulling them, our group looked at any existing literature and then filled in the (many) blanks, negotiating criteria that we could all live with. We came up with the following.

Removal criteria:

  1. No (or a minimal, stable) residual pneumothorax
  2. No air leak
  3. Less than 150cc drainage over the last 3 shifts. We do not use daily volumes, as it may delay the removal sequence. We have moved away from the “only pull tubes on the day shift” mentality. Once the criteria are met, we begin the removal sequence, even in the evening or at night. This typically shaves half a day from the hospital stay.

Removal sequence:

  • Has the patient ever had an air leak? If so, they are placed on water seal for 6 hours and a followup AP or PA view chest x-ray is obtained. If no pneumothorax is seen, proceed to the next step.
  • Pull the tube. See tomorrow’s blog for a video on how to do it.
  • Obtain a followup AP or PA view chest x-ray in 6 hours.
  • If no recurrent pneumothorax, send the patient home! (if appropriate)

Click here to download the full printed protocol.

Lateral Chest X-Ray For Pneumothorax? Waste of Time!

Pneumothorax is typically diagnosed radiographically. Significant pneumothoraces show up on chest xray, and even small ones can be demonstrated with CT.

Typically, a known pneumothorax is followed with serial chest xrays. If patient condition permits, these should be performed using the classic technique (upright, PA, tube 72″ away). Unfortunately, physicians are used to ordering the chest xray as a bundle of both the PA and lateral views.

The lateral chest xray adds absolutely no useful information. The shoulder structures are in the way, and they obstruct a clear view of the lung apices, which is where the money is for detecting a simple pneumothorax. The xray below is of a patient with a small apical pneumothorax. There is no evidence of it on this lateral view.

Bottom line: only order PA views (or AP views in patients who can’t stand up) to follow simple pneumothoraces. Don’t fall into the trap of automatically ordering the lateral view as well!

Lateral chest xray

 

Autotransfusing Blood Lost Through The Chest Tube

Autotransfusing blood that has been shed from the chest tube is an easy way to resuscitate trauma patients with significant hemorrhage from the chest. Plus, it’s usually not contaminated from bowel injury and it doesn’t need any fancy equipment to prepare it for infusion.

It looks like fresh whole blood in the collection system. But is it? A prospective study of 22 patients was carried out to answer this question. A blood sample from the collection system of trauma patients with more than 50 cc of blood loss in 4 hours was analyzed for hematology, electrolyte and coagulation profiles.

The authors found that:

  • The hemoglobin and hematocrit from the chest tube were lower than venous blood (Hgb by about 2 grams, Hct by 7.5%)
  • Platelet count was very low in chest tube blood
  • Potassium was higher (4.9 mmol/L), but not dangerously so
  • INR, PTT, TT, Factor V and fibrinogen were unmeasurable

Bottom line: Although shed blood from the chest looks like whole blood, it’s missing key coagulation factors and will not clot. Reinfusing it will boost oxygen carrying capacity, but it won’t help with clotting. You may use it as part of your massive transfusion protocol, but don’t forget to give plasma and platelets according to protocol. This also explains why you don’t need to add an anticoagulant to the autotransfusion unit prior to collecting or giving the shed blood!

Reference: Autotransfusion of hemothorax blood in trauma patients: is it the same as fresh whole blood? Am J Surg 202(6):817-822, 2011.