Here is the part of cryonics that nobody puts on a poster: almost everything that determines preservation quality is decided in the first hour, by people standing in a hospice room or a hospital corridor, working against a clock that started the moment the heart stopped. The dramatic part, the liquid nitrogen and the steel dewars in Switzerland, is the easy part. The hard part is the first response, because that is where damage is either prevented or quietly locked in.
The whole phase has one job: carry the patient from legal death to the start of cryoprotective perfusion while losing as little structure as possible. To see why the minutes matter so much, it helps to be precise about what we are racing.
The clock is ischemia, and it does not pause for paperwork
When the heart stops, the brain stops receiving oxygen, and within minutes the orderly chemistry that holds tissue together begins to come apart. This is ischemia, and it is the central antagonist of the entire procedure. Every minute of warm ischemia spends some of the structural fidelity we are trying to preserve. The race against cellular decay is not a metaphor; it is the design constraint that shapes every other decision in this article.
So the standby team is not trying to keep the patient alive in any conventional sense. They are trying to slow chemistry. Two levers do most of the work: keep some blood moving so tissue is not sitting in total stagnation, and get the temperature down, because cold is the same friend it is at -196°C, just earlier in the story. Roughly, every 10°C drop slows metabolism, which means cooling buys time directly.
Standby: being in the room before the heart stops
The single biggest lever on quality is also the least glamorous: be there. A trained Standby, Stabilization and Transport (SST) team goes on alert when a member is nearing the end of life, and ideally deploys before legal death so they are present at the bedside when it is declared. If death is sudden, they mobilize immediately instead. Either way, the goal is the same: zero gap between the physician's declaration and the start of stabilization. We explain why this matters in detail in what SST is and why it is important.
The team arrives equipped like a mobile intensive-care unit pointed at one unusual goal. The kit includes a biostasis-ready vehicle or ambulance, portable cooling systems, a mechanical chest-compression device, an airway and ventilation kit, and a supply of medications. Tomorrow.bio bases standby teams in Berlin and Amsterdam precisely so the travel time to a member is short, because travel time is ischemia time, and getting the team and the equipment to the right place at the right hour is its own logistics problem, the subject of logistics, red tape and transportation.
Stabilization: chest compressions, an ice bath, and the right drugs
Legal death must be declared by a physician. That is the legal starting gun, and only then does the team begin. The first move is to restore circulation and breathing artificially: mechanical chest compressions and ventilation push oxygenated blood, especially to the brain, so tissue is not left in total stagnation while cooling gets underway. The point is not resuscitation; it is keeping the brain supplied for the short window before deeper cooling takes over.
At the same time, external cooling starts hard and fast. The patient is packed in ice or immersed in an ice-water bath, with particular attention to cooling the head, sometimes with dedicated devices, because the brain is what we are most determined to protect. Medications are administered as well, including anticoagulants to stop the blood from clotting and other agents that protect tissue against the stress of low oxygen. Each step is aimed at the same target: drop metabolic and enzymatic activity so cellular degradation slows to a crawl until full perfusion can begin.
How we know the phase is done
First response is not finished when the team feels finished; it has explicit, checkable endpoints. The phase ends when:
- The patient has been cooled to a preliminary target core temperature, deep into the range where chemistry has largely stalled.
- Circulatory support is active and genuinely moving fluid, not just running.
- The pharmacological steps, anticoagulation and tissue protection, are complete.
- Vascular access can be prepared, so the patient is ready to hand off to the surgical phase.
That handoff is the whole point. Stabilization buys the time; the surgical perfusion phase spends it, replacing the body's water with cryoprotectant so the tissue can vitrify instead of freezing into damaging ice. One phase exists to make the next one possible.
The quality of a cryopreservation is mostly decided in the first hour, by how fast a trained team gets cold blood moving and the temperature down, not by anything that happens later in the dewar.
None of this requires believing revival is around the corner. It requires only the modest, defensible claim that less ischemia means more preserved structure, and that structure is the thing worth fighting for. The first response is where that fight is actually won or lost.