A New Aspirator

Abstract

Early in the war, Sir James Mackenzie1 proposed that in the examination of the hearts of applicants for military service more stress be laid on how the heart responds to effort. He says that if the applicant can undergo severe bodily exertion without distress, it is fairly safe to assume that any irregularity or systolic murmur present is without significance. This is not new, but it lends great emphasis to the examination of the circulatory apparatus as a whole and to judging a heart by the circulation it can maintain. Heretofore, cardiac examination has concerned itself principally with detecting imperfect valves, sclerotic arteries, and dilated or hypertrophied myocardium. The function tests were developed to detect inefficiency of the heart in maintaining the circulation and impending heart failure.In 1915, Swan2 reviewed the heart function tests proposed up to that time. Tigerstedt, Stone, Goodman and Howell, and many others have sought to arrive at a formula from the interrelation of different phases of the blood pressure reading that would give an index of the cardiac efficiency.The tests that seem to offer most promise are those based on the reaction of the heart to bodily exertion. Exertion in the presence of a markedly inefficient heart brings on palpitation, dyspnea and distress. The search has been for any sign or signs brought out on exertion which would indicate minor degrees of cardiac inefficiency. According to Circular 21 of the Surgeon-General's Office, the rapidity of the pulse and respiration persisting two minutes after hopping a hundred times on one foot should be viewed with suspicion. However, according to Mackenzie3 and the observations of Bafringer,4 it is only in an extremely limited number of cases that the pulse rate after exercise is of value in determining cardiac efficiency. Following Graupner,5 Barringer" has sought from the blood pressure curve following exertion to determine what he calls the "cardiac reserve." The rise of blood pressure after exercise normally takes place in thirty seconds. If the heart's capacity has been exceeded during the exercise, the height of the blood pressure is not reached for sixty or seventy seconds. The amount of exercise measured in foot pounds that can be undergone without this delayed rise is the index of cardiac reserve. It seems to make no difference which group of muscles is employed in the. exercise. The work which the average man between 20 and 30 years can perform without showing a delayed rise is from 6,000 to 12,000 foot pounds. In inefficient hearts it frequently drops to 1,000 foot pounds or less.Kahn7 has recently applied such function tests as deal with pulse rate and blood pressure following exercise to over 200 cases, including the normal, tachycardias, bradycardias, neurocirculatory asthenias, etc. His results appear definite. But before such function tests can be of significance in these diseases, the relation of the test to cardiac failure must be more firmly established. Hence the most urgent need just now is a function test wi...