Patient Transports

Q. Hi, I am wondering what the best practice is for air transporting a patient with a pneumothorax treated with a chest tube. Is a commercial 3 bottle

Medevac helicopter

system sufficient or should you also place a Heimlich valve with the 3 bottle system or simply a Heimlich valve for air transport. Thanks, Derek

A. Heimlich valves were designed by Dr. Harry Heimlich to facilitate air transport of wounded service members in Vietnam.1 The problem with Heimlich valves is the lack of a way to collect fluid drainage. Allowing fluid to flow onto the floor of the aircraft as it was done originally in combat violates standard precautions, and jury-rigging some sort of collection bag presents the risk of outflow obstruction with subsequent tension pneumothorax. These challenges led to the development of the Pneumostat chest drain valve about 10 years ago. This closed unit includes a self-contained 30 mL collection chamber to catch any fluid that may drain from the pleural space in a patient with pneumothorax. The two valves are comparable in size as illustrated here.

Patients with potential for greater volumes of fluid drainage, or longer transport times can use the Express Mini 500 drain. It is a full-featured chest drain about 9 inches high and 5 inches wide with a collection chamber capacity of 500cc, a mechanical one-way valve, option for suction (-20cmH2O if connected to a vacuum source), and safety features present in larger, more traditional drains. It is made of plastic, without risk of breakage you may see with bottles.

Historically, the U.S. Military required placing a Heimlich valve as close to the patient as possible and then connecting the tube to a chest drain. That’s because flight condition simulation testing demonstrated that during rapid decompression and

Air Force Medical Evacuation

descent, water could be sucked out of the water seal chamber, leaving the patient unprotected. This instruction was revised in 2008 after testing of the Atrium model 4050 drain. Since this drain has a dry, mechanical one-way valve rather than a water- dependent one-way valve, there is no danger of losing the patient protection with changes in cabin pressure. While the Express Mini and the 4050 use water to demonstrate air leak, the water does not create the one-way valve; thus, no Heimlich is needed. In fact, the instructions warn against using a Heimlich with this type of drain. In addition, these drains with mechanical suction regulators and one-way valves are less position-sensitive than the water-based drains.

The decision to use a Heimlich with a drain should be based on the type of drain used and the pressure swings patients would be exposed to during transport. The Air Force tested for 8000 to 45000 feet altitude. If your patients will not be exposed to these conditions, I would not recommend combining a Heimlich with a traditional drain. Having two one-way valves could increase resistance to air leaving the chest.

In preparing patients for air transport, it is essential to carefully review a chest radiograph for the presence of extrapulmonary air. Unfortunately, there is no research that predicts the amount of extrapulmonary air that may be acceptable for flight.2 Other diagnostic imaging such as ultrasound and CT scan may be used to confirm the diagnosis. It is also important to consider the mechanism of injury and the risk for pneumothorax during the transport period. For example, a patient with flail chest (multiple ribs fractured in multiple places) is at high risk for lung injury, even if a pneumothorax is not evident on initial evaluation. Consider the altitude of the planned air transport, the length of the anticipated trip, and whether the patient will require positive pressure ventilation, which increases risk for tension pneumothorax.3

If there is any question about the presence or size of a pneumothorax, it should be treated before flight. Patients with untreated pneumothorax are at risk for significant expansion of the trapped air at altitude which can change a small, clinically insignificant pneumothorax into a life-threatening tension pneumothorax. Increasing intrapleural pressure can cause desaturation and hemodynamic compromise.2,4 In-flight chest decompression is fraught with hazard and should be avoided if at all possible.

1. Heimlich HJ. Heimlich valve for chest drainage. Medical instrumentation. Jan-Feb 1983;17(1):29-31.

2. Currie GP, Kennedy A, Paterson E, Watt SJ: A chronic pneumothorax and fitness to fly. Thorax 2007;62:187-189.

3. Kaczala GW, Skippen PW: Air medical evacuation in patients with airleak syndromes. Air Medical Journal 200827(2):91-98.

4. Essebag V, Halabi AR, Churchill-Smith M, Lutchmedial S: Air medical transport of cardiac patients. Chest 2003;124(5):1937-1945.