In some ways, Susanna Deforest was typical of those who suffer from Colorado's thinner air after arriving from a low elevation. A 20-year-old from Pennsylvania, she felt sluggish when hiking up a trail to the popular Conundrum Hot Springs near Aspen, lacking much energy. She had to stop frequently to rest.
But in critical ways, her personal physiology masked what was happening as her case of high-altitude pulmonary edema, serious in its own right, turned deadly. She wasn't breathing hard, nor did she cough. She didn't turn blue. There were no obvious telltale signs to alert her and her companions that on Aug. 18 her blood oxygen saturation was dropping dangerously low.
When she died early the next morning at an elevation of 3,160 metres, the oxygen saturation in her blood was at about what is commonly found in climbers who are between 6,700 and 8,500 metres in elevation unaided by oxygen.
Dr. Steve Ayers, the coroner of Pitkin County, announced Sept. 11 that her cause of death was high altitude pulmonary edema and high altitude cerebral edema. The former, HAPE, is more common and can precede the latter, HACE, which is exceedingly rare. However, HACE can occur without HAPE.
This was an extreme case of the dangers of hypoxia, or the effect of oxygen deprivation on human tissues. It also poses questions for those who survived about whether they could have done anything differently to prevent the death. In this case, the answer is probably not.
Mountain sickness is relatively common, afflicting about a quarter of all visitors to Colorado resorts above 2,430 metres in elevation who arrive from sea level. Young men most commonly suffer. They eat heavily, drink too much alcohol, and still plow forward, skiing with gusto. The usual advice is to take it easy for a few days, stay hydrated, and get plenty of rest.
High-altitude pulmonary edema (HAPE) ordinarily doesn't show up until the second or third day. It can affect people at elevations as low as 1,830 metres, but it's more common at about 2,440 metres.
Aspen and Vail are both a little above 2,440 metres. Telluride is at 2,670 metres, but most people visiting there stay at Mountain Village, elevation 2,910 metres. Mt. Crested Butte, the slope-side town, is 2,860 metres. Most lodges in Summit County are 2,740 metres or above.
The cases of HAPE are relatively rare. Just one visitor in every 5,000 to 10,000 visitors to Colorado mountain resorts will suffer HAPE, according to Dr. Peter Hackett, who has made hypoxia, or oxygen deprivation, a central part of both his research and his mountain-climbing career. He summited Mt. Everest in 1981 and in later years ministered to climbers at the 5,490-metre base camp.
At Aspen Valley Hospital, physicians see HAPE victims once or twice a month although, on at least one occasion, there were three cases within a 24-hour period. Victims of the condition, also called acute mountain sickness, invariably arrive on their third night at altitude after their afflictions have worsened. Ayers said they complain about trouble with breathing and they can't sleep. Sometimes they can hear fluid gurgling in their chests, and the sound worries them.
"It should worry them," said Ayers. It's a telltale symptom of HAPE.
These cases of HAPE are invariably remedied with the simple prescription of supplemental oxygen, about three litres a minute. The patients can return to their hotel rooms, oxygen cannulas in their nostrils.
Fatalities resulting from HAPE used to be more common in Colorado, the nation's highest state with an average elevation of 2,070 metres. But travellers have become better educated and clinics in high-mountain valleys better able to respond.
Still, fatalities do occur. Several years ago, a visitor to Mt. Crested Butte died of HAPE. A hunter in the San Juan Mountains also died.
More rare and more deadly is cerebral edema, or HACE in which fluids build up in the brain. Rapid response can make all the difference. Ayers recalled a case several years ago of a young woman staying in Snowmass Village suffering from HACE. The lodge was probably at about 2,870 metres, the base elevation for which cerebral edema occurs. In that case, she was given oxygen immediately at Aspen Valley Hospital and put on a helicopter to a level-one trauma center in Denver, where neurologists are on staff around the clock. She didn't need them, though. Getting off the helicopter in Denver, she had recovered.
In the case of Deforest, supplemental oxygen would have made all the difference. But her symptoms were atypical.
She had flown to Denver on Aug. 13, spending the night in Golden, elevation 1,730 metres. The next day she travelled to Dillon, elevation 2,780 metres, where she lingered for two days and probably started developing HAPE, according to the report of Ayers, the coroner.
The next day, on Aug. 17, she and her companions set out from Aspen to hike up the Conundrum Hot Springs trail. It starts out at 2,650 metres and, 14 kilometres later, ends up at the hot springs, just below treeline at 3,400 metres in elevation.
Ayers said she struggled up the trail, needing frequent stops for rest, but her companions said she did not exhibit obvious signs of breathing distress.
Her symptoms were subtle and atypical, as is true in 10 to 15 per cent of cases. A healthy person at sea level has an oxygen saturation of 96 to 98 per cent in their blood, said Hackett. Oxygen saturations typically drop to 89 or 90 when people are at 2,740 metres in elevation.
For a normal person standing on top of Mt. Everest, unaided by supplemental oxygen, it would be 40 or 50.
As the young woman struggled up the Conundrum trail, her oxygen saturation levels probably dropped to the level of the world's highest peaks. As you develop HAPE, your oxygen level continues to drop, even if you are not ascending in elevation. HAPE, in this case, then continued into HACE. "It's no mystery that she had high-altitude cerebral edema," said Hackett.
Had the woman breathed heavily instead of just feeling lousy, she or her companions might have figured out that rapid descent was necessary. Instead, they hunkered down in a tent, sort of waiting out the storm. That was a fatal if understandable decision.
Arriving at 1:30 a.m., the rescue helicopter was unable to land, because of its weight. Instead, the helicopter had to burn off fuel. It didn't land until 5:30 a.m. By then, she was dead.
But from the testimony of a key witness and a timeline put together by the Pitkin County deputy coroner, it almost certainly would have made no difference had the helicopter been able to land the first time. When the companion returned to the tent after shining her lights at the helicopter, she found the woman had stopped breathing.
There may be cases of victims of HACE brought back from the brink of death, but Ayers said he's unaware of any. Victims of cardiac arrhythmia can be brought back from the brink of death. But when the brain has swollen to the point it is causing cardiac arrest, it can't be reversed.
Had the victim and her companions carried a book of Wilderness Medicine, the text that Ayers carries with him on his travels around the world, they might have diagnosed her HAPE and then HACE. But few of us carry such books when backpacking or any place else.