Scuba technology born from one of MCW’s earliest recorded discoveries
Edgar End, MD ’36, (plaid coat) examines the suit worn by his partner Max Gene Nohl, who moments earlier, surfaced after breaking the world diving record in 1937 off the shores of Lake Michigan. He used a breathing mixture developed by Dr. End that forever changed hyperbaric medicine.
As his partner descended into the wintery waters of Lake Michigan, a young doctor knew that his research and calculations would be the difference between failure, success and certainly, the diver’s safety. By the time Max Gene Nohl resurfaced unscathed, he had broken the world’s diving record, and Edgar End, MD ’36, had made history by discovering the artificial breathing mixture that made the feat possible.
More than 75 years later, Dr. End’s legacy continues in the hyperbaric medicine advances being made today at the Medical College of Wisconsin.
“I feel honored to be walking in Dr. End’s footsteps,” said Harry T. Whelan, MD, Professor of Neurology and Pediatrics at MCW, the Bleser Family Endowed Chair of Neurology at Children’s Hospital of Wisconsin. He directs MCW’s Hyperbaric Medicine Unit. “We owe a lot to Dr. End’s early work with helium and oxygen as a breathing mixture for commercial and naval diving, and hyperbaric oxygen for decompression sickness and carbon monoxide poisoning.”
A native of the Milwaukee area, Dr. End’s interest in diving began as a teenager when he invented a makeshift breathing device and began studying the effects of breathing under pressure. He and two friends built a helmet out of an old water tank, a piece of motorcycle windshield and plumbing parts. They attached the helmet to two garden hoses and a large tire pump, and explored the bottom of a stone quarry.
Dr. End graduated from the Marquette University School of Medicine in 1936. He served as Assistant Clinical Professor of Environmental Medicine at Marquette; as an intern at Milwaukee County General Hospital; and later as Director of the Milwaukee County Hyperbaric Chamber, which was built in 1932 for the treatment of compressed air tunnel workers. Dr. End was considered the city’s foremost specialist in hyperbaric oxygen therapy (HBOT), the medical use of oxygen at a level higher than atmospheric pressure.
HBOT was first used as a treatment for “the bends,” scientifically known as compressed air illness or decompression sickness (DCS). Today, it is also used to treat a number of conditions including air or gas embolism, crush injuries and other acute traumatic ischemia, necrotizing soft tissue infections, problem wounds, carbon monoxide poisoning and delayed radiation injury.
Decompression sickness causes bubbles of inert gases, primarily nitrogen, to form within tissues of the body when leaving a high-pressure environment. It most commonly affects divers, especially after spending extended periods of time beneath the water, or at great depth, without ascending gradually and making decompression stops to slowly reduce the excess pressure of the dissolved gases. DCS also may affect submariners or people who fly in unpressurized aircraft.
By 1937 at the age of 26, Dr. End was already a pioneer in the experimental use of artificial breathing mixtures rather than compressed air for divers. Early artificial breathing mixtures were considered dangerous because nitrogen, one of the gases used, dissolves in a diver’s body fluids and causes nitrogen narcosis, an alteration of consciousness similar to drunkenness. Dr. End believed that helium was much less soluble in fat and would have little narcotic effect. Although the U.S. Navy had tried replacing nitrogen with helium in the 1920s only to discover that it caused DCS, Dr. End was not deterred.
Dr. End successfully tested his new “heliox” mixture on himself and Nohl in the hyperbaric chamber at Milwaukee County Hospital. Nohl was a graduate engineer and experienced diver from the Massachusetts Institute of Technology. He had approached Dr. End with a self-contained underwater breathing unit that he and two partners had built, with the intention of diving to explore the wreck of the Lusitania off the Irish coast.
On Dec. 1, 1937, Dr. End and Nohl set the world deep sea diving record off the shores of Lake Michigan. Wearing the diving suit and breathing the heliox mixture designed by Dr. End, Nohl sank 420 feet to the bottom of the lake. The “Deepest Dive” was broadcast live on NBC radio. The Journal of Industrial Hygiene and Toxicology published news of the record dive and associated experiments.
“They had actually planned for a 375-foot dive, not 420,” Dr. Whelan said. “But Nohl decided he wanted to go all the way to the bottom. Dr. End had to get out his slide rule and recalculate new decompression stops.”
Together, Dr. End and Nohl developed and built the first self-contained underwater breathing apparatus (scuba). Famed French diver Jacques Cousteau would consult their research in the 1940s to invent his prototype aqua-lung, the first open-circuit scuba to reach worldwide popularity and success.
Dr. End performed further experiments in the hyperbaric chamber during World War II and broke new diving records. He and his associates built most of the specialized gear for the U.S. Navy including frogman gear, underwater demolition team outfits and suits worn by mine disposal experts.
“Research continues today on how to extend the use of rebreathers by Navy SEALs to advance into enemy waters without producing bubbles,” said Dr. Whelan, who holds the rank of captain and is a diving medical officer in the U.S. Navy. Dr. Whelan is a consultant to the Navy Experimental Diving Unit and serves as the senior undersea medical officer for the “Deep Submergence Unit.”
Dr. End and Nohl conducted the first prolonged “immersion” experiment to test the effect of great pressure on the human body for extended periods of time. The two men stayed in the hyperbaric chamber at a pressure equivalent to 102 feet of sea water for 27 hours. The first dive tables, which allow a diver to determine a decompression schedule for a particular dive, were published in 1942 based on their work. The tables greatly reduce divers’ risk of developing decompression sickness.
As Director of the Milwaukee County Hyperbaric Unit, Dr. End treated nearly all local cases of the bends occurring in divers and compressed air tunnel workers. He also successfully treated carbon monoxide poisoning and arterial gas embolism, a more serious form of decompression illness that occurs when air bubbles enter the lungs, travel through the arteries and cause tissue damage by blocking blood flow at the small vessel level. Dr. End believed hyperbaric oxygen also could benefit patients with acute stroke, gas gangrene, chronic ulcer, skin grafts, arteriosclerosis and migraines. He was famous for remaining in the hyperbaric chamber with all of his patients during treatment.
Dr. End died in 1981 at the age of 70 with high hopes for the future of hyperbaric oxygen. Dr. Whelan and others continue his groundbreaking research in MCW’s Hyperbaric Unit, which performs more than 1,000 treatments per year. The team is investigating the benefits of hyperbaric medicine for the treatment of ischemic stroke, radiation-induced cerebral necrosis, traumatic brain injury, soft-tissue necrosis in the head and neck, cerebral palsy and multiple sclerosis.
“We are seeing success with reversing cell damage, stimulating new blood vessel growth and improving circulation to tissues,” Dr. Whelan said.
MCW and NASA together are pioneering the use of hyperbaric oxygen in conjunction with near-infrared Light-Emitting Diode (LED) technology for treating diabetic skin ulcers and diabetic macular edema, serious burns and the complications of cancer treatment. LED technology has been found to increase cell metabolism and growth, which leads to tissue regeneration and healing, and adds to the benefit of hyperbaric oxygen. NASA and MCW also are exploring the benefits of hyperbaric oxygen and infrared light for counteracting the harmful effects of weightlessness and radiation in space.
Dr. Whelan also continues research to improve the safety of deep-sea diving. He is investigating whether a ketogenic diet decreases oxygen toxicity symptoms in divers. Dr. Whelan says the future of mankind is beneath the sea.
“It’s important for us to go down much deeper and stay much longer. The average ocean depth is nearly three miles, but we’ve confined our exploration to just a few hundred feet,” he said. “A majority of the earth has yet to be explored. There are undiscovered million-year-old animals and plants with potentially useful biological properties and products.”
Cover photo source: Box #1, Folder 7, Edgar End Papers, 1910-1981, Mss #344, Local History Manuscript Collection, Milwaukee Public Library, Milwaukee, Wis.
Other photos source: Box #2, Scrapbook, Edgar End Papers, 1910-1981, Mss #344, Local History Manuscript Collection, Milwaukee Public Library, Milwaukee, Wis.
Legacy in hyperbaric medicine
Hyperbaric Medicine Practice, second edition.
The discoveries of Edgar End, MD ’36 — his development of the breathing mixture that launched the creation of scuba gear and his determination that hyperbaric oxygenation dramatically reduces red cell agglutination, a significant advance in the prevention of “the bends” during rapid decompression — are among the earliest in the history of MCW. Those discoveries paved the way for the future of hyperbaric medicine.
In his autobiography Unexpected Odyssey, Eric P. Kindwall, MD, a Milwaukee physician who came to be known as the “Grandfather of Hyperbaric Medicine,” describes meeting Dr. End in the 1950s and the significance of those early discoveries. Dr. Kindwall, who had a teaching appointment at MCW in the 1990s, died in 2012. The definitive textbook on hyperbaric medicine is written by Dr. Kindwall and Harry T. Whelan, MD, Professor of Neurology and Pediatrics at MCW, and the Bleser Family Endowed Chair of Neurology at Children’s Hospital of Wisconsin, who directs MCW’s hyperbaric unit.
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