Kanto Institute crestMax the UndyingKanto Institute · Program 07
Peer review complete · record v2Original research · Program 07Published 12 August 2026

Recovery of coordinated neurological function in a canine subject 41 minutes after certification of death

Max the Undying: hypothermic acellular perfusion and graded reoxygenation as a reversible boundary for clinical death

R. Hayashi1M. Okonkwo2L. Vasquez-Reed3S. Tanabe1A. Brenner2K. Iwasaki3D. Osei1Y. Fujimura2
Read the protocolResults & dataDOI 10.4821/kitc.2026.0812
Three veterinary clinicians in white coats and surgical masks working over Max, a Shiba Inu, on the theatre table during the Program 07 reperfusion protocol

Figure 1

Theatre record, T+03:41. Cannulation site inspection during the final reoxygenation step. Frontal near-infrared saturation had recovered to 63 % at the moment of capture; sinus rhythm returned eleven minutes later without inotropic support.

mm:ss
41:07
Asystole before reperfusion
oesophageal
18.2 °C
Minimum core temperature
vs. baseline
94 %
Cortical EEG power recovered
at time of report
214
Days of sustained survival

Abstract

Structured summary as accepted by the editorial board, 12 August 2026. Word count 612. Reporting conforms to ARRIVE 2.0 and to the CONSORT extension for single-subject compassionate interventions.

Background. Clinical death is treated as an event. Cellular evidence suggests it is an extended process, and that most neurological injury attributed to arrest is in fact generated during uncontrolled reperfusion. If the commitment step of that injury can be held closed pharmacologically while metabolic demand is suppressed thermally, the operative question becomes not how long a subject has been dead but under what chemistry the interval was spent.

Methods. Following certification of death by two independent veterinarians and consented enrolment, a 9-year-old male Shiba Inu (subject designation MU-01, "Max") underwent femoral cannulation, whole-body washout with the cold acellular perfusate KRP-7, controlled cooling to a core temperature of 18.2 °C, and nine-step graded reoxygenation over 96 minutes. Monitoring comprised continuous eight-channel electroencephalography, bilateral near-infrared spectroscopy, invasive arterial pressure, arterial blood gas analysis at five-minute intervals and serial neurofilament light chain sampling. The pre-registered primary endpoint was return of coordinated cortical activity; secondary endpoints were return of spontaneous circulation, quantitative EEG spectral recovery, handler recognition and 180-day survival.

Results. Coordinated cortical activity returned at 67 minutes after certification. Spontaneous circulation returned at 232 minutes. Quantitative EEG recovered to 94 % of pre-arrest spectral power by day 6. Behavioural testing at day 9 demonstrated preserved handler recognition, intact spatial navigation and no deficit on the modified Glasgow canine neurological scale. Histology of parallel tissue controls localised the protective effect to preserved mitochondrial ultrastructure in CA1 pyramidal neurons and to the absence of spectrin cleavage in cortical layers III and V. Survival is ongoing at 214 days with normal cardiac function under an implanted cardioverter-defibrillator, unremarkable renal and hepatic panels, and no seizure activity on repeated 24-hour ambulatory recordings.

Interpretation. A 41-minute interval of certified death was reversed without measurable neurological cost. The boundary of recoverable death appears to be set by perfusate chemistry and reoxygenation kinetics rather than by elapsed time alone. Translation to human out-of-hospital arrest is the explicit objective of the successor trial. The result should be read as a single consented subject with a favourable arrest witness interval and an intact airway, not as a generalisable survival claim; the contribution is mechanistic, and the burden of replication falls to the porcine multi-centre arm now in progress.

Principal findings

Three conclusions that change what a death certificate means

01

Cellular death is a process, not an instant

Structural markers of irreversible neuronal injury did not appear until 68–74 minutes of normothermic ischaemia in matched tissue controls, far later than the 4–6 minute clinical dogma. Immunohistochemistry for spectrin breakdown products, cytochrome c translocation and terminal deoxynucleotidyl transferase labelling showed a sharply non-linear onset rather than a gradual decline, which means the interval between certified death and cellular death is a therapeutic window with a measurable, chemically adjustable width rather than a fixed clinical constant.

02

The damage is caused by the rescue, not the arrest

Graded reoxygenation reduced markers of reperfusion injury by 71 % against flash-reperfusion controls. Mitochondrial complex I in the ischaemic state accumulates reduced flavin and succinate; abrupt reintroduction of oxygen drives reverse electron transport and a superoxide burst within seconds, followed by permeability transition, cytochrome c release and caspase activation. Restoring oxygen too quickly is therefore the dominant cause of the neurological devastation historically attributed to the arrest itself, and the schedule of restoration is an independent, controllable variable.

03

Perfusate chemistry can suspend the mitochondrial commitment step

KRP-7 held the mitochondrial permeability transition closed through 41 minutes of asystole. Blocking that single commitment step preserved 94 percent of cortical EEG power and, critically, the encoded memory of a familiar handler. Sequestering the commitment step rather than scavenging its downstream products is what separates this result from four decades of antioxidant trials that reduced biochemical markers without changing neurological outcome.

Case chronology

The 41 minutes

Times are relative to certification of death at 14:31 KST on 11 January 2026. Reconstructed from theatre telemetry, perfusion logs and continuous video.

  1. T−00:12

    Cardiac arrest during elective imaging

    Max, a 9-year-old male Shiba Inu under sedation for a scheduled abdominal ultrasound, entered ventricular fibrillation secondary to a previously undiagnosed arrhythmogenic right ventricular cardiomyopathy. Telemetry captured 14 seconds of polymorphic ectopy with progressive QT prolongation before degeneration into a disorganised fibrillatory rhythm at a dominant frequency of 7.8 Hz. Advanced life support was initiated within 40 seconds: mechanical chest compressions at 110 min⁻¹, biphasic defibrillation at 4 J·kg⁻¹ escalating to 6 J·kg⁻¹, adrenaline 0.01 mg·kg⁻¹ at three-minute intervals, and amiodarone 5 mg·kg⁻¹ after the third shock. End-tidal carbon dioxide never exceeded 11 mmHg, indicating that compression-generated cardiac output remained below the threshold associated with survivable perfusion.

  2. T+00:00

    Death certified by two attending veterinarians

    After 12 minutes of unsuccessful resuscitation, absence of cardiac electrical activity, brainstem reflexes and spontaneous respiration was documented independently by Dr. R. Hayashi and Dr. M. Okonkwo. Time of death was recorded at 14:31 KST and countersigned in the theatre register before any Program 07 equipment entered the room.

  3. T+00:04

    Consent obtained for Program 07 salvage protocol

    The owner, a registered participant in the institute's post-mortem research consent programme, authorised enrolment. The pre-positioned on-call team reached the theatre in 3 minutes 40 seconds with the perfusion circuit already primed and thermally equilibrated, a logistical precondition that had been rehearsed in eleven prior dry runs with a median activation-to-flow interval of 9 minutes 12 seconds. No pharmacological or mechanical support was reinstituted between certification and cannulation, preserving the integrity of the certification interval for later adjudication.

  4. T+00:09

    Femoral cannulation and cold perfusate washout

    Bilateral femoral access established. Blood volume was displaced with KRP-7, a cold acellular perfusate buffered to pH 7.6 and loaded with a mitochondrial-permeability inhibitor, a hydrogen-sulfide donor and a broad calpain antagonist. Displacement proceeded until venous effluent haematocrit fell below 3 percent, confirming near-complete removal of erythrocytes and therefore of the iron-catalysed Fenton chemistry that drives hydroxyl radical formation during reperfusion. Perfusate was buffered with tris-hydroxymethyl aminomethane rather than bicarbonate because bicarbonate systems lose buffering capacity as carbon dioxide solubility rises at low temperature, and colloid oncotic pressure was maintained at 19 mmHg with hydroxyethyl starch to limit interstitial oedema and the resulting rise in cerebral compartment pressure.

  5. T+00:24

    Core temperature reaches 18.2 °C

    Cerebral oxygen demand fell to an estimated 11 % of normothermic baseline. Non-pulsatile flow was held at 45 mL·kg⁻¹·min⁻¹ with continuous near-infrared spectroscopy monitoring of frontal saturation. Each degree of cooling below 37 °C reduces cerebral oxygen consumption by roughly 6 to 7 percent through Q10 kinetics, but the dominant protective effect at this depth is not metabolic arithmetic: sub-physiological potassium and the closed mitochondrial permeability transition pore together prevent the calcium-loaded depolarisation cascade that ordinarily commits neurons to death within minutes of ATP exhaustion. Adenosine triphosphate in serial cortical biopsy homogenate remained at 34 percent of baseline at the end of the hold, against 4 percent in untreated normothermic controls.

  6. T+00:41

    Controlled reperfusion begins

    Oxygen tension was raised in nine graded steps over 96 minutes to avoid a reperfusion burst. Coordinated cortical activity, meaning inter-hemispheric coherence above 0.4 in the 4 to 12 Hz band sustained for 60 seconds rather than isolated epileptiform spiking, appeared on channels F3 and F4 at T+01:07. Advance to each successive step required frontal tissue oxygen saturation to be stable within 2 percentage points for 120 seconds and arterial lactate flux to be non-increasing; two steps were held beyond their scheduled duration when lactate transiently rose, and no step was skipped.

  7. T+03:52

    Return of spontaneous circulation and brainstem reflexes

    Sinus rhythm at 96 bpm without inotropic support. Pupillary light reflex, corneal reflex, gag reflex and spontaneous ventilation returned in that caudal-to-rostral sequence over 34 minutes, a recovery order consistent with the differential ischaemic tolerance of brainstem nuclei relative to cortical and hippocampal fields. Cardiac troponin I peaked at 4.8 ng·mL⁻¹ at six hours and normalised by day four; no vasopressor or inotrope was administered at any point after reperfusion.

  8. T+09 days

    Discharge with intact recognition behaviour

    Max reliably discriminated his owner's voice from three matched controls, navigated a familiar obstacle course at 88 % of pre-arrest speed, and showed no measurable deficit on the modified Glasgow canine neurological scale. Serum neurofilament light chain, the most sensitive available marker of axonal injury, peaked at 82 pg·mL⁻¹ against a control-cohort mean of 741 pg·mL⁻¹ after only 8 minutes of untreated normothermic arrest, and returned to within the reference interval by day 12.

Figure 2

Day 9: recognition, navigation, temperament

Max at the pre-discharge neurological assessment. Gait symmetry measured 96 % of pre-arrest baseline on pressure-plate analysis. Startle habituation, appetitive motivation and social approach behaviour were indistinguishable from the eleven age-matched controls in the institute's veterinary cohort.

The finding that matters most is not that the heart restarted. It is that the animal that woke up was recognisably the same animal.

Max the Shiba Inu resting alert on a stainless steel examination table nine days after the procedure

Mechanism

Why the interval is chemical

Four coupled processes determine whether an ischaemic neuron recovers. Program 07 intervenes in each of them separately, which is why the effect is additive rather than marginal.

M1

Energetic failure and ionic collapse

Within 20 to 30 seconds of arrest, cerebral phosphocreatine is exhausted and adenosine triphosphate falls below the threshold required by the sodium-potassium ATPase. Membrane potential collapses, glutamate floods the synaptic cleft, NMDA receptor channels open, and cytosolic free calcium rises by two orders of magnitude. Hypothermia to 18.2 °C reduces the rate of ATP consumption by approximately 89 percent, and sub-physiological perfusate potassium of 3.6 mmol·L⁻¹ raises the depolarisation threshold, so the ionic cascade is slowed at both ends rather than merely delayed.

M2

The mitochondrial commitment step

Calcium overload combined with oxidative stress opens the mitochondrial permeability transition pore, an event that is functionally irreversible: the inner membrane potential collapses, the organelle swells, the outer membrane ruptures, and cytochrome c enters the cytosol where it nucleates the apoptosome. KI-118, a non-immunosuppressive cyclophilin D ligand, holds the pore closed with a dissociation constant of 40 nmol·L⁻¹ at 18 °C. In matched tissue, pore-opening measured by calcium retention capacity was 6 percent of untreated controls at the end of the hold.

M3

Reperfusion oxidative burst

Succinate accumulated during ischaemia is oxidised the instant oxygen returns, driving reverse electron transport through complex I and generating superoxide at rates far above physiological flux. Graded reoxygenation across nine steps allows succinate to be consumed at a rate matched to the capacity of superoxide dismutase, catalase and the glutathione-ascorbate couple supplied in the perfusate. Malondialdehyde and 8-hydroxy-2-deoxyguanosine, markers of lipid and DNA oxidation, were 29 percent of flash-reperfusion controls.

M4

Proteolysis and structural commitment

Calcium-activated calpains cleave spectrin, tau, ankyrin and the cytoskeletal scaffolding that defines dendritic architecture. Once that scaffolding is degraded, restoring perfusion restores metabolism but not the circuit. SNJ-1945 at 6 mg·kg⁻¹ suppressed spectrin breakdown product formation to below the detection limit of the assay through the entire 41-minute interval, which is the most plausible explanation for preserved handler recognition, a memory encoded in distributed hippocampal and cortical synapses rather than in bulk tissue viability.

Translational path

What follows

Out-of-hospital cardiac arrest

Roughly 90 % of the 350,000 annual out-of-hospital arrests in the United States are fatal, and survivors carry a heavy burden of hypoxic brain injury. A field-deployable washout would extend the intervention window from minutes to tens of minutes.

Organ procurement

Donation after circulatory death is currently constrained by warm ischaemic time. KRP-7 preserved renal and hepatic function markers within transplantable range for 6.5 hours in the parallel organ arm.

Neuroprotective surgery

Deep hypothermic circulatory arrest for aortic and complex neurovascular repair is presently limited to about 40 minutes. Graded reoxygenation may substantially widen that ceiling.

Stroke and trauma

The same mitochondrial commitment step governs penumbral loss in ischaemic stroke and in haemorrhagic shock. A phase I human safety study of KRP-7 is in regulatory review.