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BLB Oxygen Mask and Aviation

1995; Elsevier BV; Volume: 70; Issue: 10 Linguagem: Inglês

10.4065/70.10.1020

1942-5546

Joseph M. Miller,

Spaceflight effects on biology

To the Editor: The historical profile of Dr. W. Randolph Lovelace II in the April 1995 issue of the Mayo Clinic Proceedings (page 316) was a well-deserved acclamation. Perhaps, serendipity guided this surgical fellow to devise a means of oxygen delivery that would revolutionize air travel. Initially, Dr. Lovelace was interested only in finding a way to deliver oxygen more efficiently to patients than with the oxygen tent, which had many disadvantages. After the BLB mask was perfected for clinical use, the thought was that pilot error, related to hypoxia, could be ablated by use of the same mechanism. Cerebral hypoxia had long been recognized as a hazard of high-altitude flight. Northwest Airlines and other flight providers were profoundly concerned with the increasing number of airplane crashes worldwide. The idea that the use of oxygen by mask could prevent these accidents was appealing to Dr. Lovelace and the airline. Providing oxygen to personnel and passengers by mask might, therefore, mark a new beginning in aerospace medicine. The most critical problem for the aviator was the oxygen supply, which is at a barely acceptable level at 10,000 feet. Hypoxia causes a serious evil at this and slightly higher altitudes in which light-headedness, irresponsibility, and irritability may progress to stupor, unconsciousness, and death. In 1875, Gaston Tissandier and two companions rose to 21,000 feet in a balloon. They had three bags of oxygen with them and intended to breathe from them when they were weak. Lack of judgment led to loss of consciousness and the deaths of the two companions. The demonstration of an easy method of oxygen delivery to prevent accidents at altitudes higher than 10,000 feet was vitally necessary. To test the hypothesis, Northwest Airlines installed a large tank of oxygen and connected it to individual outlets and BLB masks on a Lockheed 14H twinmotored airplane. On Mar. 10, 1939, the 1,150-mile flight from Minneapolis to Boston was made in 4l/2 hours. The airplane flew at about 270 miles an hour at an average altitude of 23,000 feet. Coming into Boston only a few minutes before a raging blizzard that reduced visibility to zero, the airplane carried the simple equipment that would allow commercial aircraft to fly safely at high levels and thus attain great speeds. The uneventful flight was made in conjunction with a conference on physiologic problems of aviation at the Harvard Fatigue Laboratory. The passengers included Drs. Walter M. Boothby, Lovelace, and Arthur H. Bulbulian, the inventors of the BLB mask. The representatives of Northwest Airlines were Mal B. Freeburg and Erick Paselk, pilot and copilot, respectively, and Karl O. Larson and Ralph E. Giror. In addition, H. T. Lewis of Trans-Canada Airlines and Violet Freeburg, the wife of the pilot, were on board. Dr. Alfred Uihlein and I were invited guests. The advent of pressurized cabins has provided a sealed cabin into which air is pumped to maintain an effective internal altitude considerably lower than that at which the airplane flies. As a safeguard, the mask is still present above all airplane seats and is readily available to provide oxygen in emergency situations. Although not routinely used, the BLB mask remains to signify a considerable advance in aviation medicine.