Determining whether someone is dead or alive may seem straightforward, but it’s actually a complex process. Doctors rely on a combination of physical exams, lab tests, and vital signs to conclusively determine if a person has died. Here’s an in-depth look at how doctors make this determination.
Checking for Signs of Life
The first thing doctors do when trying to determine if a patient has died is perform a basic physical exam looking for signs of life. They will check for a pulse, breathing, pupil response, and movement. If none of these signs are present, the patient may be dead. However, lack of breathing or pulse alone does not necessarily mean someone is dead. The next steps help confirm death.
Breathing
Doctors will check for breathing by listening for sounds of respiration, watching the chest for rise and fall, and feeling for breath on their cheek. If no breathing is detected, they will open the airway by tilting the head back and lifting the chin, then check again. If there is still no breathing, it’s a strong sign of death.
Pulse
Checking for a pulse allows doctors to see if the heart is still beating and pumping blood. They will check for a carotid pulse in the neck as well as a femoral pulse in the groin. Lack of a pulse indicates the heart is no longer functioning.
Pupil Response
Doctors will shine a light into the eyes to see if the pupils respond by constricting. Non-responsive, fixed pupils that remain dilated even with light stimulation often occur when the brain is no longer functioning and is a sign of death.
Movement
Doctors will look for any spontaneous movement or reaction to stimuli like pain. If there is no response to firm pressure applied to the nails, sternum, or other areas, it indicates a loss of reflexes and brain function.
Diagnostic Testing
In addition to a physical examination, doctors may run tests to assist in determining death:
Lab Tests
Blood tests can measure dissolved oxygen levels. Extremely low oxygen saturation indicates respiratory and cardiac failure.
Imaging Scans
CT scans and MRIs allow doctors to look for signs of irreversible brain damage and loss of brain function.
ECG
An ECG monitors the electrical activity of the heart. It can show if the heart has lost all electrical function and is asystolic or “flatlined.”
EEG
An EEG records brain wave activity. Lack of brain activity on EEG over an extended time is a strong indicator of brain death.
Vital Sign Absence
For doctors to definitively pronounce someone dead, they must confirm an absence of vital signs. This includes:
| Vital Sign | What It Measures |
|---|---|
| Breathing | Respiratory drive |
| Pulse | Heartbeat |
| Blood pressure | Blood circulation |
| Reflexes | Brain function |
Breathing, pulse, blood pressure, and reflexes are all controlled by the brain stem. If these vital signs are absent, it indicates the brain stem is damaged or dead. Doctors must document a consistent lack of breathing, pulse, blood pressure, and reflexes over an observation period before legally certifying death.
Observation Period
An observation and examination period is necessary to confirm death. For organ donation, the recommended period is at least 5 minutes. After 10 minutes with no vital signs, the chances of spontaneous recovery are extremely unlikely. Most protocols require 20 minutes or more of continued absent vital signs before death can be declared.
Types of Death
There are several categories doctors use to determine and classify death:
Clinical Death
Clinical death occurs when breathing and blood circulation stop. It may arise from cardiac arrest, respiratory arrest, or other conditions. Clinical death is reversible in some circumstances if the underlying cause can be treated.
Brain Death
Brain death means irreversible loss of brain function. All parts of the brain must be damaged and nonfunctional, including the brain stem which controls vital signs. Brain death is legally considered death in most areas.
Biological Death
Biological death occurs when all cells and tissues in the body lose function. The body begins decomposition within minutes to hours after the heart stops. Biological death cannot be reversed.
Pronouncing Death
Formal steps must be followed for a doctor to pronounce someone legally dead:
- Perform an examination to determine absent vital signs
- Document lack of pupil response, movement, pulse, and respiration in the medical record
- Note the time vital signs were lost and the time death is pronounced
- Complete and sign a formal declaration of death document
- Have a second doctor confirm the examination findings if available
- Notify authorities such as the coroner or medical examiner if required
Pronouncing death allows the issuance of a death certificate and the ability for the decedent’s family to proceed with burial or cremation arrangements.
Resuscitation Attempts
In some cases, doctors may attempt to revive someone through resuscitation efforts like CPR and cardiac defibrillation. This can restore vital signs that were temporarily lost. Doctors will not try to resuscitate if:
- There is a do not resuscitate (DNR) order
- The patient has a terminal illness or untreatable condition
- Resuscitation is unlikely to be successful
- Brain death has occurred
When resuscitated patients regain a pulse and resume breathing, they are no longer considered clinically dead. However, those resuscitated after prolonged clinical death often have severe brain damage.
Reversible Factors
In rare circumstances, clinical death is reversible if certain underlying conditions are promptly treated. Potentially reversible causes doctors rule out include:
Hypothermia
Hypothermia slows metabolic processes and can preserve vital organs after clinical death. Successful resuscitations have occurred after hypothermic cardiac arrest even with prolonged submersion in icy water.
Drug Overdose
Overdoses depress respiratory drive and can cause apparent death. With respiratory support and antidote treatment, normal breathing may resume.
Medical Conditions
Electrolyte abnormalities, endocrine disorders, heart block, and other treatable conditions may lead to temporary loss of vital signs.
Alternative Death Determination Methods
Some alternative methods have been proposed for determining death, but are not widely used clinically:
Decomposition
Allowing the body to decompose irreversibly confirms biological death. However, this is impractical for organ donation or timely funeral arrangements.
Putrefaction
Evidence of putrefaction like rigour mortis, algor mortis, and livor mortis can indicate death occurred at least several hours prior.
Automatic External Defibrillators
Portable defibrillators designed for lay rescuers often have algorithms to determine if shocked rhythms are “non-shockable” and indicate death.
Controversies
There are some controversies around declaring death in certain scenarios:
Organ Donation
Some argue determining death is rushed in potential organ donors. Protocols require permanent absent vital signs before organ recovery.
Religious Objections
Some faith groups argue various forms of life support should be continued indefinitely after clinical death. They object to brain death criteria.
Reversible Factors
It’s challenging to definitively determine when loss of brain or organ function becomes irreversible.
Resuscitation Technology
New preservation techniques like ECMO may allow resuscitation after longer periods of clinical death than currently possible.
Conclusion
Determining death is a complex process requiring intensive physical examination, diagnostic testing, and observation for absent vital signs. Doctors follow systematic protocols to conclusively determine if someone has died. While there are some controversies, the standardized approach used today ensures accurate determinations of death in most scenarios.