eMJA: Morgan, Economy class syndrome: a forgotten lesson

Letter

Economy class syndrome: a forgotten lesson

MJA 2001; 175: 669-670

To the Editor: The editorial by Gallus and Baker,¹ and subsequent correspondence which speculated about prolonged calf pressure contributing to causing deep vein thrombosis,² reminded me of an undergraduate lecture in 1948 about pulmonary embolism in people who slept in deck chairs in London air raid shelters during World War II.

This lecture was given by Simpson, then a lecturer in forensic medicine (and later a respected authority in this specialty), who reported a significant increase in deaths from pulmonary embolism (to 24) in September and October 1940, soon after serious night air-attacks on London began.³ This compared with only four in September and October 1939. Twenty-one of these 24 deaths occurred in, or soon after leaving, air raid shelters.

The pople who died were mostly elderly, obese and often had varicosities of the leg veins. A typical case was that of an overweight, 60-year-old woman who complained of numb legs and swollen ankles after sitting for 10 hours in a deck chair — she dropped dead in the street while walking home, eight minutes after leaving the shelter. Autopsy showed multiple small pulmonary embolisms and small tags of very fresh antemortem clot in the tibial veins.

Simpson concluded that the process was mainly mechanical (calf compression causing obstruction, stasis, oedema and thrombosis), as sleeping in deck chairs causes compression of calf veins against the front edge of the chair for many hours. He proposed that people in air raid shelters should therefore be given provision for lying down. Indeed, by the time his letter was published, in December 1940, he noted that the number of cases of fatal pulmonary embolism were already decreasing, coinciding with the provision of bunks in the shelters.

Stasis remains the precipitating factor in Virchow's triad of thrombus formation (abnormal blood flow [stasis], endothelial injury and hypercoagulability). Venous flow rate while lying down slows to half on standing and a third on sitting,⁴ even before calf compression is added.

In 1940, civil authorities acknowledged the cause of an excess of cases of fatal pulmonary embolism and preventive measures were implemented, with documented success within two months. In 1954, Homans reported venous thromboembolism "probably due to sitting travel" by air and car.⁵ In 1988, calf pressure in cramped seating was blamed by the originators of the popular but restrictive term "economy class syndrome".⁶ In the 1990s, and in relation to the 2000 Olympic Games, a host of cases of flight-related pulmonary embolism were reported.¹ But, in 2001, it seems the evidence for a causative effect must still be considered "circumstantial".¹

Lloyd K Morgan
Retired General Practitioner, PO Box 150, Lorne, VIC 3232

Gallus AS, Baker RI. Economy class syndrome [editorial]. Med J Aust 2001; 174: 264-265.
Slonim L. Economy class syndrome Med J Aust 2001; 175: 176
Simpson K. Shelter deaths from pulmonary embolism. Lancet 1940; 2: 744.
Ferrari E, Chevallier T, Chapelier A, Baudouy M. Travel as a risk factor for thromboembolic disease: a case-control study. Chest 1999; 115: 440-444.
Homans J. Thrombosis of the deep leg veins due to prolonged sitting. N Engl J Med 1954; 250: 148-149.
Cruickshank JM, Gorlin R, Jannett B. Economy class syndrome. Lancet 1988; 2: 497-498.

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