Perils of flying economic class: Deep Vein Thrombosis or the “Economy Class Syndrome” By Shashi K. Agarwal, MD

The term ‘economic class syndrome’ was coined by Cruickshank and associates in the journal Lancet in 1988, describing an increased risk of deep vein thrombosis in the legs after a prolonged episode of air travel. It was suggested to be more common in the economy class due to its cramped quarters and the difficulty in frequent ambulation.

Subsequent studies have confirmed the increased risk for deep vein thrombosis with frequent and prolonged air travel. Pooled data from 3 studies reveal that the relative risk for DVT is 26% higher for each 2-hour increment of flight duration.

It is estimated that about 2 billion people travel by air each year. With the advent of long haul flights, travelers are often sitting for long periods of time. According to scientific studies, oral contraceptives, sitting in a window seat, advanced age and pregnancy increases DVT risk in long-distance travelers. The risk also appears to be higher in short people (<165 cm) or tall people (>185 cm), and those that are obese (BMI over 25 kg/m2).

Formation of a blood clot in the deep veins of the legs is commonly known as deep vein thrombosis or DVT. This can be symptomless or may result in pain, swelling, redness and warmth in the affected extremity. DVT is dangerous as the blood clot can dislodge and travel to the lung resulting in a serious medical emergency called pulmonary embolism or PE. PE can be fatal. Trauma, prolonged inactivity and conditions such as cancer, infections, and certain inflammatory and cardiovascular diseases increase the propensity to develop DVT.

Travelers can take some precautions to decrease the risk of DVT:

1. Stand, stretch and walk around the cabin every 2 hours.
2. Keep well hydrated. This includes limiting alcohol and coffee intake.
3. Wear loose clothing, especially from the waist down.
4. Perform foot, ankle and knee exercises (flex and extend) while sitting, every hour or so.
5. Walk at the airport during layovers.

People at high risk should also get professional compression stockings (providing 15-30 mm Hg pressure) or get one dose of low molecular weight heparin prior to a flight longer than 8 hours. Aspirin has shown no benefit in preventing deep vein thrombosis.

 

Inactivity: An Important Cardiovascular Risk Factor by Shashi K. Agarwal, MD

Cardiovascular disease (CVD) is the leading cause of death for both men and women in the United States. It is estimated that over a million Americans die of cardiovascular events each year. Although several risk factors for CVD are non-modifiable (age, male gender, race and family history), many are amenable to intervention. These include elevated blood pressure, abnormal blood sugar, high cholesterol, smoking, obesity, high fat and high calorie diet and excess stress. The American Heart Association (AHA) recommends that blood pressure be kept under 140/90, fasting blood sugar less than 110mg/dl, LDL cholesterol below 100 mg/dl, cessation of smoking, a body mass index of less than 25kg/m2 and eating a heart healthy diet. Moderate alcohol intake (less than 2 drinks per day) and low dose aspirin in high risk groups also protects against cardiovascular disease. Another modifiable behavior with major therapeutic implications is inactivity. AHA recommends all Americans partake in physical activity of at least 30 min/day on most days of the week, given its substantial health benefits.

Inactivity or a sedentary lifestyle is associated with increased cardiovascular events and premature death. Sedentary behavior, measured by television viewing time, has been associated with adverse cardiovascular health, increased obesity, diabetes mellitus, cancer and early death.(International Journal of Epidemiology. 2011;40(1):150-159)A review of several studies have confirmed that prolonged total sedentary time (measured objectively via accelerometer) has a deleterious relationship with cardiovascular risk factors, disease and mortality outcomes (Curr Opin Cardiol. 2011 Sep;26(5):412-9.)

The beneficial effects of exercise have been recognized in several occupational groups. Chair bound double decker bus drivers in London have more coronary heart disease than mobile conductors working on the same buses.( Lancet. 1953;265:1053-1057). Postal workers delivering mail by foot similarly have lower incidence of coronary disease than their office based colleagues.( Lancet. 1953;265:1111-1120). Railroad workers and longshoremen have reduced incidence of coronary heart disease compared to those in less active occupations. (Am J Public Health. 1962;52:1697-1707 and N Engl J Med. 1975;292:545-550.)

The beneficial effects of regular exercise is evidenced from several well recognized scientific studies. Leisure time exercise reduced cardiovascular mortality during a 16 year follow up of men with high risk of coronary heart disease in the MRFIT study. (Int J Sports Med. 1997;18 (suppl 3):S208-S215). In the Honolulu Heart Study, elderly men walking more than 1.5 miles per day similarly reduced their risk of coronary disease.( Circulation. 1999;100:9-13). Walking was associated with cardio-protection in the Nurses’ Health Study (N Engl J Med. 1999;341:650-658) and moderate activity in post menopausal women was similarly associated with a reduced risk of coronary disease in the Iowa Study (JAMA. 1997;277:1287-1292). People engaging in regular exercise also derive other desirable health benefits such as decreased rate of strokes, reduced incidence of cancer, decreased pain and stiffness in arthritis, improvement in erectile dysfunction and significant psychosocial benefits. There is also an increase in life span of about 3 years (Lancet. 2011;378:1244-1253. Epub 2011 Aug 16)

Regular physical activity helps reduce several cardiovascular risk factors: obesity, dyslipidemia, hypertension and diabetes mellitus. In patients with established cardiovascular risk factors, it helps prevent coronary occlusion and heart attacks. In patients with established coronary disease, it helps improve angina free activity levels and decreased death rates. In patients with heart failure, exercise improves heart function and quality of life. It also improves walking distance in patients with peripheral artery disease.

Therapeutic activity should incorporate range of motion exercises, resistance training as well as an aerobic workout. Aerobic exercise improves cardio-respiratory fitness, whereas resistance exercise training improves muscular strength. Together, they have salutary cardiovascular effects. Stretching exercises such as yoga reduce sympathetic activity and improve several other cardiovascular risk parameters. A varied mix of exercise regimens allow this therapeutic leisure activity to be enjoyable and ensures long term adherence.

The Centers for Disease Control and Prevention and the American College of Sports Medicine recommended in 1995 that all Americans target at least 30 minutes of moderate intensity physical activity on most, and preferably all days of the week. (Pate RR, Pratt M, Blair SN, et al. Physical activity and public health: a recommendation from the Centers for Disease Control and Prevention and the American College of Sports Medicine. JAMA. 1995;273:402-407.) Most professional guidelines continue to concur with these recommendations.

Sedentary lifestyle is an important cardiovascular risk factor. The benefit of regular exercise of moderate intensity and moderate duration in the prevention of cardiovascular disease remains irrefutable. Physical activity is an easy, cheap and effective way to avoid cardiovascular disease. And the benefits accrue, irrespective of the age of initiating an exercise program.