Gedankenexperiment: “Long-haul” Anesthesia vs Getting to Mars

One of the APEX crew trained and worked for 4 years in a center where it was not uncommon to find yourself caring for patients who would be “under” for 10 hours or more. Cases approaching 20 hours were uncommon but not unheard of, and as a staff member, there was a very good chance you’d find yourself providing care for one of these challenging “long-haul” cases at some time.

The cases we speak of usually involved craniofacial reconstructions with many teams of specialty services, including pediatrics, neurosurgery, plastics, ENT, ophthalmology, maxillofacial, radiology, and anesthesiology providing care. Often, it involved craniofacial deformities—particularly memorable cases involved severe hypertelorism, with eyes so widely spaced it seemed the child would have to crank their head far to the left or right just to obtain a monocular view of what was straight ahead. In nearly every case, there were other congenital anomalies.

When considering the management of “long-haul” cases, we recall a paper in the Journal of Surgical Research that systematically analyzed the relationship between operative duration and complications across surgical specialties. The study revealed that complications increased with duration, approximately doubling with each operative epoch exceeding two hours. Metanalyses demonstrated a 14% increase in the risk of complications for every half-hour of additional time.

What’s this got to do with Mars?

There’s much talk these days about humans someday settling on Mars. This vision is strongly articulated by a polymath who makes cars, launches rockets, puts spy and communication satellites into semi-permanent orbit, and has engineered a cyborg-like interface to unlock human potential. This later enterprise, Neuralink™, involves nano- and neurotechnologies implanted as a brain-computer interface designed to translate one’s thoughts into action. It’s all heady stuff. But Mars?

Mars is a long (!!) way away. There is no single answer for how far Mars is from Earth because it all depends, as neither Earth’s nor Mars’ orbits are perfectly circular, and Earth orbits the sun at 67,000 mph while Mars clocks in at 54,000 mph. In August 2003, Earth was at its closest recorded distance of 34.8 million miles (we will not be this close again until 2237). When Earth and Mars are opposite the sun from each other, that distance is some 259 million miles. If we compute an average, a metric of little meaning without context, that’s way further than Earth is from the sun. No matter where Mars is relative to Earth, it’s very far away.

While a patient is under our care, we assume responsibility for all functioning systems, especially those we’ve pharmacologically incapacitated. We breathe for them, ensure oxygenated and nutrient-rich blood reaches their cells, assume mastery of their autonomic nervous system, control fluid balance, thermoregulate, blunt conscious and somatic sensations, and protect them from the ongoing surgical assault. The longer the case, the more demanding our tasks as we endeavor to ensure some degree of homeostasis. With reanimation, we want the patient minimally back to their preop baseline—in some cases, even better.

The challenges we face in providing such care grow and can multiply with each passing hour. We see in this a corollary, maybe even a metaphor of sorts for the polymath’s vision of establishing a living foothold on Mars when he stated, “we are less than 5 years away for uncrewed, less than 10 to land people, maybe a city in 20, but for sure in 30, civilization secured.” Thinking of the challenges of caring for a single patient for 5, 20 or 30 continuous anesthesia hours got us musing about the challenges of homeostasis and risk…….are humans up to the challenges of getting to and living on Mars?

You may think this is an odd juxtaposition of one’s thoughts. But let’s conduct our own gedankenexperiment, a Germanic word for the complex musings that Einstein engaged in, translated as “thought experiments.” While a bit of a stretch, the more we considered it, the more it all seemed to align with what we do when we care for a patient having a “long-haul” procedure. Consider some of the challenges we face in assuring homeostasis in the OR and then doing the same for those involved in a “long-haul” Martian venture—one that may be permanent. Let’s see where this takes us.

If living on Mars is the destiny of some, what are the “costs”?

This is a complicated question! The journey involves a daunting calculus, but what about long-term microgravity, cosmic radiation exposure, ubiquitous organ system effects, and being away from family and friends, maybe forever? What if something breaks? What about contingency plans? All are apt considerations, but there is more to consider—so much more.

Humans were not designed to accommodate anesthesia drugs; anesthetic drugs were designed to accommodate humans. One does not need to be a polymath to recognize that humans, without Sisyphean enterprise, cannot handle or accommodate space.

Let’s look, point-by-point, at some of the challenges of space flight and Mars colonization and see if anything along the way conjures up thoughts of a “long-haul” case you might have been involved in.

It’s a fact that space flight alters human DNA. Radiation injury may very well be the single greatest concern, and methods to prevent it are elusive but essential. Studies from the Icahn School of Medicine at Mount Sinai, NASA, and elsewhere collected blood from astronauts who flew in the space shuttle over a 3-year period and found DNA mutations in all 14 studied astronauts. The concerns were an increased risk of cardiovascular disease and cancer.

International Space Station (ISS) astronauts spend a lot of time in space, averaging 4-6 months at a time, with a few spending nearly a year there. There are concerns that the cerebral vasculature stiffens in response to the microgravity of space with unclear consequences. Consider this, even after touchdown on Mars, if you weighed 150 pounds on Earth, you’d now weigh 57 pounds. Have you seen videos of astronauts coming off the space shuttle or ISS and needing help to walk? Changes in muscle physiology, the brain’s vessels, bone density, and blood circulation affect gait, neuromuscular physiology, and sensation.

Immunosenescence, neuroocular syndrome, and sarcopenia are major hits astronauts experience in microgravity. Space is not friendly to humans, and radiation exposure keeps returning to the top of the list of risk factors because it comes in a couple of ways. Naked protons emitted by that big fireball in the sky, critical to life here at home base, are of enormous but not the only radiation concern for space pioneers. So is the galactic cosmic radiation from other stuff that’s out there, like supernova events. Being in a capsule hurtling toward Mars and then landing there poses the potential for experiencing intense and protracted radiation exposure.

We must also consider the human psyche. Biosphere II, where 8 people lived for 2 years in what was supposed to be a self-sustaining enclosure, was plagued by multiple issues, including a failure to naturally produce enough oxygen, requiring an exogenous supply to be piped in. Food shortages and considerable psychological turmoil wore heavily on the biospherians, despite visits—separated by glass panels—from friends, family, and spectators. Isolation space travel for many months or years? The effects are unknown and perhaps unknowable until the venture unfolds. The learning will come in the doing.

The grand ecological experiment in the Arizona desert raised more questions than answers and cost over $200 million (in 1990s dollars) over its several-year lifespan. What’s the total cost of sending a team to live on Mars? Trillions of dollars.

We don’t mean to be naysayers—recall that just 6 decades ago, it seemed improbable to keep a patient safe under general anesthesia for “long-haul” times now routinely employed. Consider that a whole-face transplant at the Mayo Clinic may require as many as 30 hours of continuous anesthesia and surgical care. Human ingenuity and its plasticity can solve daunting problems. That vocal polymath who we alluded to earlier and those like-minded might be on to something! But it does give us pause.

As CRNAs ourselves, we understand the challenge of fitting CRNA continuing education credits into your busy schedule. When you’re ready, we’re here to help.