Introduction and historical background
In recent years, guidelines for determining “brain death” have undergone a notable shift. The guidelines of Canada, the United States (US) and the United Kingdom (UK) no longer require irreversible loss of brain function to determine “brain death”, instead adopting merely a “permanent” loss of function [1-3]. Similarly, the Swiss Academy of Medical Sciences plans to amend its guideline [4]. The current term “irreversible” is to be replaced with “permanent” [5], even though Article 9 of the Swiss Transplantation Act states that a person is dead when brain functions have “irreversibly” ceased. This raises the question of whether a “permanent” standard of organ failure is sufficient for determining death.
This terminological change originates in the concept of “non-heart-beating donation” (NHBD), essentially a return to the earliest practice of organ procurement. Before the concept of “brain death”, most organs were retrieved from patients after cardiac arrest [6]. The term commonly used today for this method of organ procurement is “donation after circulatory death”.
In the donation after circulatory death procedure, death is declared after a predefined waiting period following cardiac arrest, intended to ensure that circulation has permanently ceased. This interval reflects the maximum time during which autoresuscitation may occur and is typically set at 5 minutes in countries with established donation after circulatory death programmes [7]. Regardless of the specific legal framework, however, any determination of death must remain consistent with the general understanding of death. This becomes questionable when only “permanent” loss of function is required.
The general meaning of “death”
Reliable determination of death requires more than identifying a loss of organ function. Rather, it requires that the patient is dead. This presupposes a specific understanding and a clear definition of “death”. Depending on the definition used, specific, observable changes (criteria or signs of death) must be identified and demonstrated using appropriate diagnostic tests and procedures (diagnostic methods). A coherent concept of death therefore comprises at least three levels: the definition of death, the criterion of death and the tests used to determine death [8] (see table 1, left column). These levels build on each other and are logically ordered: tests (level 3) must demonstrate the criterion of death (level 2), which in turn must fulfil the underlying definition of death (level 1).
Table 1: Death and irreversibility.
| Components of a concept of death | General meaning | Irreversibility |
|---|---|---|
| 1. Definition of death | “Cessation of life”(death as the opposite of life) | Death is irreversible. Humans cannot return to life after death. |
| 2. Criterion or sign of death | Loss of function (e.g. loss of cardiopulmonary or brain function) | The loss of function must be irreversible. |
| 3. Tests for determining death | Tests to determine the relevant functional or organ failure from level 2 | Proof of loss of function/organ failure according to level 2 and of its irreversibility. |
Given this structure, the definition of death (level 1) determines both the criteria and the diagnostic procedures for determining death (levels 2 and 3). The secular understanding of the term “death” and its use in everyday language imply that people cannot return to life after death [8-10]. Precise definitions of death may remain controversial. Yet across all perspectives – medical, biological, social, legal and cultural – irreversibility is a common denominator. Death, as the “cessation of life”, is final and irreversible. Consequently, only an irreversible state can serve as a valid criterion for death and the tests for determining death must demonstrate irreversible loss of function (see table 1, right column).
The difference between “irreversible” and “permanent”
Irreversible loss of function is present when a function will neither return spontaneously nor be restored by any available intervention [8-10]. By contrast, the abovementioned guidelines define permanent loss of function as one that will not return spontaneously, given a prior decision not to attempt restoration of that function [1-3, 5]. With regard to circulatory function, this state is typically assumed after approximately 5 minutes. In patients without resuscitation attempts, autoresuscitation has been observed only within a period of 4 minutes and 20 seconds after cardiac arrest [11]. However, if resuscitation efforts were initiated and then discontinued due to lack of success, autoresuscitation may still occur for up to 20 minutes [12] and cardiac activity can be re-established even later with medical intervention. Accordingly, irreversible loss of cardiac function can only be assumed after prolonged attempts to restart circulation for at least 30 minutes.
After only 5 minutes of cardiac arrest, the brain is not irreversibly damaged. It is traditionally assumed that irreversible brain damage occurs approximately 8 to 10 minutes after blood circulation stops [13, 14], with the brainstem being much more tolerant to ischaemia than the cortex [15]. However, a large study on survival after out‑of‑hospital cardiac arrest found survivors with a favourable neurological outcome even in cases where 30 minutes had elapsed between cardiac arrest and the start of CPR [16].
At 5 minutes of cardiac arrest, there is no evidence of irreversible loss of function in either the heart or the brain. Therefore, the permanent standard fails to meet the necessary condition for reliably determining death. Death is irreversible and cannot be reversed. Permanent loss of function, as specified in the aforementioned guidelines, cannot be recognised as a valid sign of death.
Justification of “permanent”
The UK Code of Practice states that the term “permanent” was adopted because it “better aligns with clinical reality for most confirmations of death” [3]. This appears to be the only explicit justification in the literature for departing from the standard of irreversibility. The underlying argument is that, in the traditional determination of death based on circulatory arrest, it was not customary to wait until irreversibility had been established [10]. Instead, it was considered sufficient to determine that cardiac activity would not resume and that no attempt would be made to restore it.
However, this practice was justifiable only prior to the 1950s, when cardiac arrest could not be reversed by intervention. The last heartbeat marked a state that would inevitably lead to the irreversible state of death. While declaring a patient “dead” immediately after cardiac arrest was not entirely accurate, it was inconsequential as organ procurement was not contemplated. By the time funeral or autopsy procedures took place, irreversibility had undoubtedly occurred.
With the advent of cardiopulmonary resuscitation techniques and positive-pressure ventilation in medical practice, it became clear that pronouncing a patient dead immediately at the moment of cardiac arrest was incorrect. When such declarations were nevertheless made, they represented a prognosis rather than a diagnosis of death [9]. A prognosis of imminent death is not equivalent to its determination.
Whether a given approach to determining death is consistent with previous or common practice is not decisive. A valid determination of death must conform to the general understanding of death and its undisputed characteristics, especially its irreversibility. Therefore, diagnostic tests must demonstrate an irreversible condition. This requirement is not met by the new “permanent” standard. Notably, some proponents of this approach even concede that patients who are subject to the “permanent” standard are not actually dead, stating “that the cessation of circulation is not irreversible at that point. When this situation is viewed from a strict biological perspective, critics are correct that the donor is not dead at that moment” [10].
Conclusion
The distinction between “permanent” and “irreversible” is substantial. A permanent loss of cardiac or brain function does not suffice to establish death. This has direct implications for all individuals considering organ donation, for whom it is essential to know whether their condition at the time of organ removal meets the standard of irreversibility of death. At the very least, transparent communication about the meaning of the amended guidelines in Canada, the US and the UK is required. The Swiss Academy of Medical Sciences should adhere to the current irreversibility standard [4] when revising its guidelines.