Here are some excerpts from a book I recently read, "Replaceable You: Adventures in Human Anatomy," by Mary Roach.
Dentures have been around since the 1700s. Who would rely on a masticator when they could opt for false teeth? In fact, people often had both. They’d masticate in the privacy of their room, then install their dentures and head into the dining room to sit down and not eat. Far from being a functional replacement for molars and incisors, false teeth at the time were largely ornamental, a sort of wig for the mouth. “With uncertain adaptation to the jaws, and primitive fastening arrangements, false teeth were in general almost useless for eating,” wrote the late John Woodforde in The Strange Story of False Teeth, a book I chewed through to here expectorate a few morsels.
“Wait, so why would you use anything other than an autograft?”
Goverman swivels from his computer to answer. Supply problems, in short. With a major burn, surgeons quickly run out of graftable (unburned) skin. “Sometimes we have to use the soles of the feet, the scalp, even the scrotum,” Goverman says. Areas that have been harvested can be reharvested after they’ve healed, but that can take two or three weeks. In the meantime, an allograft (skin from another human, typically a deceased tissue donor) or a xenograft (skin from another species) protects the wound. It also prevents some of the fluid loss. Deep burns destroy the closed-loop integrity of the circulatory system; leaking capillaries (among other things) send blood pressure dangerously low. Temporary grafts also make changing bandages less painful for patients, and they help keep them warm. Because they’ve literally lost their coat. Burn survivors can develop hypothermia in a 70-degree room. ICUs and ORs for survivors of major burns are often kept at 90 or even 105 degrees, nurses and surgeons sweating under their scrubs and sterile gowns.
Another question for Goverman: If skin grafts taken from other bodies are just a temporary dressing, why then did the frog and dog and rabbit skin grafters of nineteenth-century medical journals (and of the previous chapter) write that these grafts would “take”? Because they did. “It becomes your skin for a few days,” Goverman says. One of the things that happens with a big burn is that the immune system is suppressed. The lowered vigilance means a piece of foreign tissue is not flagged as dangerous. So the body follows normal skin protocols, extending the welcome handshake of capillary growth. For a matter of days, people were in fact part frog or puppy or rabbit.
An allograft lingers longer under the radar, because skin from a fellow Homo sapiens is a closer match than skin of another species. It likely buys you weeks, not days. Whatever is used, person or beast, a graft also helps prevent infection. The immune system’s temporary slowdown makes this critical in the early days after a serious burn. When someone dies after a serious burn, it’s often because of sepsis: a localized infection has gone systemic.
Eventually an allograft for a bad burn will be replaced with a permanent graft of the patient’s own skin. The surgeon can wait for the allograft to be rejected and slough off, or the surgeon can, as I believe I phrased it in a question to Goverman, rip it off.
“Ripping it off is actually nice because it freshens the wound bed.” Makes it bleed, he means. Blood is good. Blood heals. Blood feeds the new graft. “You want a nice vascular wound bed.”
For Diana, the pain, emotional and physical both, began in burn rehab: the daily lineup of physical therapy, occupational therapy, speech therapy. Worse than all of that: the first time she saw herself in a mirror. At Mass General the staff were careful to cover reflective surfaces, but a physical therapist took her to a gym that had a full-length mirror. “It wasn’t supposed to happen until much later,” she recalls. “It was a major major major major trauma.” She looks over at Jerry. “I’m thinking, he’s going to leave me. I couldn’t understand why he was still there, unless it was out of guilt.”
Jerry sets down his fork. “I told her, ‘It’s just skin. I don’t love you for your physical appearance. I love you because you’re you.’ And she didn’t say anything. And I said, ‘Are you still you?’ She said, ‘I’m still Diana.’ I said, ‘Then I still love you.’ ”
If all goes well with this line of research, gene-edited pigs will eventually be donating more than just skin. The science is moving from xenografting to xenotransplantation. “The ultimate goal would be, you’d have your own personal pig,” Goverman said. In other words, a pig edited to match your own genetics: skin, kidneys, heart—ready to use, like a car kept for parts.
Until I met one, it never occurred to me to wonder why anesthesiologists put surgery patients on a ventilator in the first place. Why would a machine need to breathe for them? It’s because general anesthesia has slowed their breathing. And because they’ve been paralyzed. General anesthesia may include a drug that relaxes (to the point of nonfunction) the muscles. Paralyzing muscles makes them easier for the surgeon to cut through, and it ensures that the patient holds still. If you were to awaken while someone has your guts on a table or your heart in their hand, things could get chaotic fast. Paralyzing the patient also makes it easier for the anesthesiologist to push the breathing tube past the vocal cords during intubation. However, it has to be done quickly, because one of those paralyzed muscles is the diaphragm, the major muscle that works the lungs. Meaning that the patient is on a fast track to suffocation.
The time pressure is intense. An anesthesiologist has but a few minutes to get the ventilator tube down the windpipe of their poised-to-suffocate patient. The longer it takes, the greater the risks: stroke, heart attack, kidney damage, brain death. All the consequences of oxygen deprivation. Generally speaking, the scariest part of going under the knife is the under, not the knife.
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