How EM specialists – and NASA – helped rescue the 33 trapped Chilean miners
I had the esteemed pleasure of consulting with the Chilean Health authorities on the recent entrapment of the 33 Chilean miners. The Chilean authorities asked for NASA’s help because of the space program’s work in enclosed harsh environments. To say that the disaster was challenging is an understatement. But my colleagues in Chile did an outstanding job, both from an emergency medicine and disaster management perspective.
I want to be perfectly clear, though, that there is a difference between consulting and actually doing the work to save those men. So although NASA gets a great deal of press for the rescue, the real accolades go to Dr. Jaime Manalich and his team. There are a number of issues that went into this rescue from an emergency medicine perspective, and I will endeavor to go over the highlights here. But make no mistake, the orchestration, treatment, and planning was a significant undertaking and the medical establishment in Chile worked extraordinarily hard to achieve the positive outcome. They made it look easy, but as you will soon see, it was anything but.
In any disaster of such scope, it is helpful to break the event and subsequent actions down into smaller pieces. Each of these pieces has its own challenges and risks. But in breaking it down, we can take a seemingly overwhelming disaster and find bite-sized, manageable steps. For the mine, the disaster was broken into five phases: initial incident, survival, sustainment, rescue, and recovery/reintegration.
The initial incident has its own peril. Essentially 700,000 tons of rock shifted and collapsed into the mine. Two of the primary concerns when there are sudden large volume changes are trauma from the blast and blast overpressure. The impact of 700,000 tons collapsing into a mine is not unlike a bomb going off. Direct and indirect trauma are the first concerns, especially for air-filled structures that are sensitive to sudden pressure changes such as the lung and intestines. Triaging these folks is as simple as finding out who can hear and who can’t. Since the middle ear is also sensitive to such sudden shifts in pressure, if the patient has difficulty hearing, they are at risk of developing abdominal pain or pulmonary edema from contusions or alveolar disruption some hours later. Fortunately, this was an old mine. The fact that the mine was over a hundred years old and had multiple shafts and cracks meant that it was leaky, and that leaky disposition prevented the blast and collapse from creating an overpressure.
The next important aspect in this phase is atmosphere. In the United States, many of our mine disasters are related to blasts from methane explosions. Although methane is common in coal mines, the mine in Chile was a gold and copper mine, and was not with the same atmospheric risk. In addition, the mine entrance was at 2,400 feet above sea level. In the depths of the mine, the miners themselves were going to be somewhere around sea level or, at worst, one atmosphere below. The possibility of asphyxiation, either due to hypoxia or toxic gases was diminished greatly both by their location in relation to sea level, the type of mine, and the leaky aeration of the mine itself.
The miners were very much masters of their own fate, particularly during this second phase. The shift leader organized the groups, divided the survival rations, and had the men start to work on digging wells for water. This alone allowed the miners to survive until they were found 17 days later. Exemplary leadership and rational thinking by their shift leader literally helped save their lives. They had dug several wells, and within a few hours it would become obvious as to which well had potable water – certain men were assigned to drink from each well and the group monitored the signs and symptoms of their gastrointestinal distress. This was a crude but effective means of triage to determine if any of the wells were indeed potable. The disaster rations consisted of cans of tuna and peaches, as well as canned milk. The men were rationed to a teaspoon of tuna, a quarter of a peach, and a sip of milk every other day, which was essentially less than 150 calories a day on average.
Once the men were found, the only supply route was a 4-inch round tube. A small torpedo-shaped supply canister, called a paloma, was used to send food and water to the men. The canister had to fit in the 4-inch round tube and could only be about 4 feet long itself, to avoid getting stuck in the shaft as it bent and flexed its way through the 2400 feet to the mine. It took a great deal of time to get the paloma to and from the mine initially, such that supplies were getting to the miners at a trickle. Water was of course the first priority, followed by the feeding of the miners. But refeeding starving people has to be done in a methodical manner. Refeeding syndrome, with sudden drops of phosphate and often potassium, is a risk when feeding previously starving patients. The body has slowed down regulated insulin production and used up liver glycogen in the starvation state. A sudden carbohydrate load can cause a sudden shift in insulin and intracellular electrolytes, driving phosphate into the cells and causing shifts in potassium, sometimes with dire consequences.
Cardiac failure, dysrhythmias, or seizures and coma are not unheard of consequences of refeeding syndrome. In addition, the miners ranged from ages 19 to 63 and with varied health states such that the predictability of this cohort of patients was going to be wide and varied. Refeeding would have to be done conservatively. The Chilean health team started with Ensure Plus due to the phosphate and potassium load and moved to Supportan due to the fact that the package would fit in the paloma more easily, and it had a good phosphate and potassium profile. Thiamine supplementation also occurred and multivitamins were supplemented. The caloric intake was taken from 500 calories to 800 to 1000, and then gradually on up over a five- to seven-day period. The rule for avoiding refeeding syndrome is “go low and go slow” and to avoid the temptation to start shoveling carbohydrate down the supply pipeline. The refeeding plan was done with concise and near textbook execution, such that not a single miner had a complication, dysrhythmias, or untoward event as a result. The men were kept at a protein sparing diet initially, and then regular food that they were accustomed to was sent down.
The mine itself was about 90 degrees with 90% humidity. The men did not have cots initially and were making use of rocks, dirt, and equipment to sleep on. Between their nutritional state, dehydration, and now sleeping on hot rocks, they were at high risk for rhabdomyolysis. One of the first tests sent down the supply pipe was the urine dipstick. This simple test would give you specific gravity to assess the degree of dehydration, ketones for both dehydration and assessment of the starvation state, protein and would also test positive for blood when myoglobin was present. Literally half of the 33 men tested positive for myoglobin. These men were targeted for higher fluid intake, on the order of 5 liters per day, in order to increase their urine output greater than 50-100cc an hour. This was successful in all of the men, such that their acute tubular necrosis was halted in this phase, and fulminant renal failure was avoided.
The sustainment phase consisted of normalizing food and water intake, but also of caring for the miners’ chronic medical ailments. One miner had type II diabetes (which was probably under good dietary control in the starvation phase), another had labile hypertension. Still others dealt with silicosis and chronic obstructive pulmonary disease.
Ninety degree heat and high humidity meant that fungal infections and potentially bacterial infections of the skin were also going to be a constant struggle. Supplementation with Vitamin D3 had to be undertaken to avoid complications due to their lack of sunlight for months. Psychological support was also going to be paramount. It’s one thing to work with someone you don’t really like that much on a daily basis, but to be trapped with them for months in an enclosed space is an entirely different psychological trial. The psych support of the families also had to be considered, as did the support of the folks working around the clock on the surface. Rescuers had to strike a balance between too much contact from the surface – which could disturb the miners’ circadian rhythms – and enough to guide the miners and maintain control of the situation.
The rescue itself was going to be a dangerous portion of the operation. Drilling from above meant the potential for falling rock below. In addition, this was no simple sled for a one hundred foot ride. The rescue pod would have to carry the men 2,400 feet to the surface. The width of the tube was determined by the drill bit width, essentially around 26 inches in circumference. This meant there would be little volume for air circulation. The men would be essentially standing at attention in this escape pod for what could be 20 minutes or could be hours depending on the stability of the rock above. This meant that orthostatic hypotension was a possibility. But in this case, the miner would not be able to get flat to restore blood to the heart and brain. This could have consequences ranging from syncope to death. Because the rock was more unstable close to the surface, there was a risk that rock could fall into the shaft and wedge the capsule, entrapping the miner in the escape capsule and tunnel. Both orthostatic hypotension and emergency escape had to be planned for.
When it came to designing the rescue capsule, the Chilean health authorities took the recommended requirements from NASA and gave them to multiple groups, with the Chilean Navy having the winning capsule design. Dr. Manalich then had the miners perform the fluid and salt loading protocol that is used by NASA for returning astronauts on the Space Shuttle. This, combined with non-pneumatic compression garments, prevented orthostasis for the trip to the surface. In addition, escape hatches and a harness to lower the miner back into the mine were available in case the escape capsule were to get stuck due to falling rock. Fortunately, this was not required. Special Oakley sunglasses that would protect the miner from debris as well as shield the cornea and retina from the bright lights were also used to prevent both uveitis and retinopathy.
Recovery and Re-Integration
Despite how good the miners looked upon reaching the surface, the Chilean health authorities had a very six sigma approach to the final stage of this rescue. Each miner was placed on a stretcher and taken to triage. Each would have additional thiamine intravenous fluids if required. Each would be fully evaluated and then flown to the hospital for further definitive evaluation. This was no doubt hard to maintain when folks were coming up looking terrific, but was a necessary part of their triage. The miners were running on adrenaline, and shortly after the epinephrine surge would subside they would declare themselves as still dehydrated, or with pneumonia, or with additional electrolyte abnormalities. In addition, reintegration to their family and society would have to take place gradually and in doses over the following days. Monitoring of their health, especially pulmonary health and psychological health would take place over many months.
This is but a taste of the many facets of the operation that the Chilean health authorities had to overcome. The success of the operation was due to the determination of the miners themselves, but also to the thorough planning and flawless execution of a complex medical and disaster plan by the Chilean government and healthcare establishment. They searched to find the answers from many consultants around the globe and, in NASA’s case, above it. But they are now the teachers. There will be many lessons learned from the Chilean mine disaster, including medical, business, and political lessons. I extend my thanks to my Chilean colleagues for allowing me the privilege of working and consulting with them. Their execution of this intricate emergency and disaster medicine plan allowed thirty three lives to be saved, and for that they deserve immense respect from their medical colleagues.