#AskDrKK: Can a patient with deep vein thrombosis fly?

#DrKKAnswers:

1.  Prolonged travel confer a 2- to 4-fold increase in risk of venous clots, a phenomenon that has been termed the "economy class syndrome" when applied to air travel.

2.  The risk is one per 100 million passengers for travel distances <5000 km (3100 miles) and 4.8 per million passengers at travel distances greater than 10,000 km (6200 miles).

3. There is an increased risk of venous clots among patients who fly longer than eight hours or further than 5000 kilometers. The risk increases by 26 percent for every two hour increment of air travel time.

4.The absolute risk of a first episode of venous clot is 1 in 4600 air flights.

5.This risk is higher for those with risk factors. Risk is increased in individuals with recent major surgery, including hip or knee arthroplasty within six weeks, increased age, obesity, prior venous clots, use of oral contraceptives, heart failure, hereditary thrombophilia)

6. Prolonged air travel may pose an even higher thrombotic risk in those with two or more risk factors for VTE.

7. In previously healthy patients who travel at least eight hours per flight (median duration 24 hours), duplex ultrasonography reveal an asymptomatic venous clots in 10 percent.

8. Blood thinners for high risk patients can decrease risk.

9.There are a number of maneuvers that travelers can use that may be beneficial during extended travel times (ie, flights of greater than six to eight hours duration). These include

• Moving about every hour or two
•  Request bulkhead seating
•  Refraining from smoking
•  Avoidance of constrictive clothing
•   Flexing and extended the ankles and knees periodically; avoidance of leg crossing; frequent changes of position while seated
• Adequate consumption of fluids to avoid dehydration
• Avoidance of agents favoring immobility (eg, sedative drugs, alcoholic beverages)
• Use of below-knee stockings

10.Compression stockings can decrease the incidence of DVT associated with prolonged flights.

11.Among patients considered to be at high risk for clots, use of properly fitted, below-knee graduated compression stockings (12 to 30 mmHg at the ankle) or one prophylactic dose of low molecular weight heparin a few hours before the flight may be protective. Aspirin is not effective in this setting.

 Maintain normal schedule using the time of the patient's home country (best for short trips; may help to keep a watch on home time).

Gradually adjust schedule by an hour or two daily, until medication is taken according to local time.

Abruptly change schedule so medication is immediately taken according to local time (may lead to extended delays between doses; not to be used with insulin).

 Screening questions

1.      Length of the journey

2.      History of tolerating prior air travel

3.      Conditions of the destination, eg, altitude, public health risks, and access to medical care.

Individuals with a medical condition that could lead to inflight illness, injury, or risk to other passengers may be required by the airline to have a medical certificate from their clinician. The certificate should state that the patient is currently stable and fit for air travel, and, if applicable, not contagious.