Deep Research Archives

The End-of-Life Experience: A Scientific Examination of Pain and Suffering Across Diverse Mortality Pathways Executive Summary This report provides a scientific overview of pain and suffering at the end of life, exploring various causes of death and the inherent complexities in their quantification. It highlights that the experience of pain is profoundly subjective, often compounded by rapid physiological changes that lead to a loss of consciousness in terminal stages. The analysis delves into distinct pain profiles and physiological mechanisms associated with cardiovascular events, cerebrovascular incidents, cancer, sepsis, traumatic injuries, asphyxiation, and severe burns. A critical aspect emphasized throughout is the intricate interplay between physical pain and psychological, social, and existential suffering, collectively termed "total pain." The report also addresses the limitations of current pain assessment tools, particularly in non-communicative or dying patients, underscoring the implications for compassionate and comprehensive end-of-life care.

1. Introduction: The Spectrum of Mortality and the Challenge of Pain Assessment 1.1. Overview of Leading Causes of Death Mortality across the globe and within the United States is primarily driven by a range of complex health conditions. Heart disease and cancer consistently stand as the two leading causes of death worldwide.1 In the United States, data from the CDC's 2021 report indicates that heart disease was responsible for 695,547 deaths, accounting for 20% of total deaths, while cancer followed closely with 605,213 deaths, representing 17% of the total.1 Other significant contributors to mortality include COVID-19, accidents (unintentional injuries), stroke, chronic lower respiratory diseases, Alzheimer's disease, diabetes, liver diseases, and kidney disease.1 A deeper examination of these leading causes reveals a significant interconnectedness, where deaths are often the culmination of complex interactions between primary diagnoses, chronic comorbidities, and acute complications. For instance, while heart disease and cancer are frequently cited as direct causes, underlying conditions such as diabetes can significantly contribute to an acute myocardial infarction.2 Similarly, cancer treatments can compromise the immune system, rendering patients vulnerable to infections like pneumonia, which may ultimately lead to death.3 Any infection, in turn, carries the risk of progressing to sepsis, a life-threatening systemic response.4 This intricate web of interacting pathologies means that isolating and precisely quantifying the pain associated with a single "cause of death" is inherently challenging. The overall suffering experienced by a dying individual is a holistic phenomenon, rather than a collection of discrete, isolated pains. This underscores the necessity of adopting a comprehensive rather than a reductionist approach when attempting to understand and address suffering at the end of life. 1.2. Defining Pain and Suffering in the Context of Dying Pain is formally defined as "an unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage".5 This definition is crucial because it inherently acknowledges that pain is not merely a physical sensation, but also encompasses significant psychological and emotional dimensions. In the context of terminal illness, the concept of "total pain" becomes particularly relevant. This broader understanding extends beyond physical discomfort to include psychological, social, and spiritual suffering.7 It recognizes that factors such as emotional distress, unresolved interpersonal conflicts, and the non-acceptance of one's impending death can profoundly contribute to the overall experience of suffering.7 Psychological distress, manifesting as anxiety, depression, hopelessness, and fear, is highly prevalent among patients receiving palliative care, with estimates suggesting that 40% to 80% experience significant distress.8 For example, a patient may have their physical pain well-managed by medication, yet still experience immense suffering due to the fear of abandonment or a perceived loss of meaning in their life.11 Therefore, providing a solely numerical "pain score" would be an inadequate and potentially misleading representation of the dying experience. A truly scientific approach to understanding suffering at death must acknowledge and characterize these non-physical dimensions, even if they resist simple numerical quantification. The focus must expand from merely "pain" to "suffering," encompassing the various forms it takes, and emphasizing that comprehensive end-of-life care must address these broader, often less tangible, aspects of distress. 1.3. The Scientific Approach to Quantifying Subjective Experience Quantifying pain, which is fundamentally a subjective experience, presents an inherent challenge in scientific assessment.12 The personal experience of pain is "fundamentally unobservable" by others, meaning clinicians and researchers must rely on indirect observations and measures to infer the pain experienced by individuals.12 These indirect methods often fail to capture the full personal context and meaning that profoundly shapes an individual's pain experience.12 Patient self-report remains the gold standard for pain assessment, typically utilizing unidimensional scales such as the Numeric Rating Scale (NRS) or Visual Analog Scale (VAS).6 However, the utility of these scales diminishes significantly as a patient's consciousness fades or their ability to communicate becomes impaired.17 The very mechanism of "self-reporting" pain, which is the cornerstone of these scales, becomes impossible. This fundamental characteristic creates a scientific paradox: how can one objectively quantify something that is inherently subjective? While pain scales assign numerical values, these numbers are interpretations based on self-reported feelings, not direct physiological measurements of an internal experience. For patients who are unconscious or non-verbal, assessment shifts to behavioral or physiological proxies 19, which are even further removed from the subjective experience and prone to interpretative challenges.19 Therefore, any "quantification" presented in this report will be an approximation, an inference, or a measure of observable indicators, rather than a direct, objective readout of internal suffering. The scientific rigor in this context lies primarily in the methods of inference and assessment reliability, rather than a definitive numerical value of the subjective experience itself. This also highlights the ethical imperative to provide pain relief based on observed signs, even if precise quantification of the internal experience is impossible.17
2. Physiological Mechanisms of Death and Associated Pain Profiles 2.1. Cardiovascular Events (Heart Attack & Sudden Cardiac Arrest) Mechanisms of Cardiac Failure A heart attack, medically known as a myocardial infarction, occurs when the blood supply to a part of the heart muscle is blocked.20 This blockage is typically caused by the rupture of fatty, cholesterol-containing plaques in the coronary arteries, leading to the formation of a blood clot.20 This interruption of blood flow starves the heart muscle of oxygen, resulting in damage or death of the affected tissue.20 Sudden Cardiac Arrest (SCA) is a distinct event from a heart attack, though a heart attack can trigger it.22 SCA is primarily an electrical malfunction where the heart's electrical activity becomes chaotic, leading to an irregular rhythm, most commonly ventricular fibrillation (VF).22 This disorganized electrical activity causes the heart to quiver uselessly instead of pumping blood, resulting in the immediate cessation of circulation.22 While a heart attack is a "plumbing problem" (a blockage), SCA is an "electrical problem".22 In the broader context of the dying process, the loss of function in one or more of the three classic vital organs—the heart, brain, or lungs—initiates a cascade of systemic failure.24 In the case of VF, consciousness and respiratory drive are lost within seconds due to the rapid and complete cessation of blood flow to the brain.24 Another trajectory of dying is Pulseless Electrical Activity (PEA), where the vascular system collapses, leading to severe hypotension and bradycardia.24 In PEA, the heart may still exhibit weak electrical activity and even some mechanical pumping (referred to as pseudo-PEA) for several minutes, but this activity is insufficient to maintain adequate circulation and eventually progresses to asystole, the complete cessation of heart activity.24 Importantly, PEA is considered a late stage in the dying process, often initiated by the failure of the brain, lungs, or vascular system, with the heart typically being the last organ to cease function.24 Pain Experience and Progression During a heart attack, common symptoms include chest pain described as pressure, tightness, squeezing, or aching.20 This pain often radiates to the shoulder, arms (frequently the left), back, neck, jaw, or upper abdomen.20 The pain is frequently severe and can be mistaken for indigestion or heartburn.21 Warning signs, such as recurring chest pain (angina) that does not resolve with rest, can precede a heart attack by hours, days, or even weeks.20 Women may experience atypical symptoms, including less pronounced chest pain and more shortness of breath, fatigue, insomnia, nausea, vomiting, or pain in the back, shoulders, neck, arms, or abdomen.21 In contrast, in cases of sudden cardiac arrest, the onset of symptoms is immediate and severe, characterized by sudden collapse, absence of a pulse, cessation of breathing, and immediate loss of consciousness.22 Due to the abrupt and complete cessation of blood flow to the brain, conscious perception of pain is lost within seconds.24 This means that while the underlying heart attack leading up to SCA can be intensely painful, the actual terminal phase of SCA results in an extremely brief, if any, period of conscious pain perception before unconsciousness supervenes. For deaths directly caused by sudden cardiac arrest, the quantification of pain in the terminal moments would thus be minimal or non-existent due to the immediate loss of consciousness. The focus on pain assessment in such cases shifts to the symptoms experienced prior to the arrest (e.g., prodromal heart attack symptoms) rather than the moment of death itself. This challenges the common notion of prolonged, conscious suffering during the immediate cardiac arrest. The observation that the heart is often the last organ to fail, particularly in deaths involving Pulseless Electrical Activity (PEA) 24, further supports the idea that for many non-VF cardiac deaths, the period of conscious suffering is limited. If the brain and lungs fail before the heart, the individual may already be unconscious or have severely impaired consciousness due to cerebral hypoxia or respiratory failure before the heart finally ceases to pump effectively. This has significant implications for understanding the experience of dying and for the goals of palliative care, which often prioritize comfort and consciousness management. 2.2. Cerebrovascular Events (Stroke & Cerebral Hemorrhage) Mechanisms of Brain Injury and Failure Stroke is characterized by damage to brain tissue, resulting from either an obstruction of blood supply (ischemic stroke) or bleeding within or around the brain (hemorrhagic stroke).27 Hemorrhagic strokes, in particular, involve the rupture of blood vessels, leading to an accumulation of blood that exerts pressure on brain tissue and increases intracranial pressure.28 This increased pressure directly damages brain cells and impairs their function. At a cellular level, stroke triggers a cascade of pathophysiological responses, including excitotoxicity (excessive neuronal stimulation by neurotransmitters like glutamate), inflammation, and various cell death mechanisms such as apoptosis (programmed cell death), necrosis (uncontrolled cell death), necroptosis, and autophagy.27 The loss of neuronal cells is the central problem, leading to the characteristic neurological deficits associated with stroke.27 Pain Experience and Progression Hemorrhagic strokes are frequently associated with the sudden onset of an extremely severe headache, often described by patients as the "worst headache of your life".28 This intense pain can be accompanied by symptoms such as nausea, vomiting, confusion, irritability, muscle pain in the neck and shoulders, and sensitivity to light.28 Rapid neurological deterioration, including loss of consciousness, inability to move or feel, vision problems, and seizures, can occur swiftly following the onset of a hemorrhagic stroke.28 It is important to distinguish this acute pain from "post-stroke pain" (central post-stroke pain or thalamic pain), which develops in approximately 10% of stroke survivors days or even years after the event.34 This chronic pain can manifest as burning, aching, or prickling sensations, often constant and worsening over time, and is frequently underdiagnosed and poorly managed.35 When considering the pain at death from a stroke, the primary focus should be on the acute, severe headache and associated neurological symptoms that precede rapid unconsciousness in hemorrhagic strokes. This suggests a very brief, intense period of conscious suffering before the brain's function is severely compromised. The suffering in these cases is intense but typically short-lived in its conscious phase. This distinction is vital for accurate pain quantification in the context of mortality, as chronic post-stroke pain is a morbidity of survival, not a feature of the immediate fatal event. 2.3. Cancer Mechanisms of Death The primary cause of death from cancer is often widespread metastases, where cancer cells spread from the original tumor to other organs throughout the body.36 Cancer can also cause death through organ failure, resulting from the physical size and stress exerted by tumors.3 Tumors can obstruct vital organs, such as the intestines or ureters, leading to blockages, or they can grow through the walls of organs like the bowel or stomach, causing perforations and severe infections.3 For instance, cervical cancer can block the ureter, causing urine backup and leading to uremia and subsequent kidney failure.3 In the lungs, cancer can cause respiratory failure, often complicated by pneumonia, particularly as cancer treatments can severely impair the immune system, making patients highly vulnerable to infections.3 Furthermore, tumors can secrete substances that increase the blood's clotting ability, significantly raising the risk of life-threatening blood clots, such as deep venous thrombosis and pulmonary embolism.3 These clots can travel through the bloodstream to vital organs like the brain or lungs, causing fatal blockages. Brain herniation is another mechanism of death in cancer patients, occurring when a brain tumor (either primary or metastatic) grows to such an extent that the brain is compressed and pushed into available spaces within the skull.3 Symptoms of brain herniation include severe headaches, high blood pressure, and an irregular pulse, which can rapidly progress to coma and loss of vital reflexes.3 Pain Experience and Progression in Terminal Stages Pain is a pervasive and significant symptom in cancer, affecting 20% to 50% of patients overall, and rising to approximately 80% in advanced stages.6 This pain profoundly negatively impacts patients' functional status and overall quality of life.6 Cancer pain can be classified by its underlying mechanisms: nociceptive pain, which arises from tissue injury (e.g., bone pain, or visceral pain described as aching, squeezing, or cramping), or neuropathic pain, which results from nerve damage (often described as sharp, burning, or electric shock-like sensations).6 The pain can be continuous or intermittent.6 Breakthrough pain, characterized by transitory increases or flares of pain even when chronic pain is relatively well-controlled, is also common.6 As death approaches, symptoms such as fatigue, shortness of breath, and drowsiness typically increase in severity, particularly in the final month of life.37 Qualitative accounts suggest that many dying cancer patients find comfort in the expectation of becoming unconscious before death, likening the process to falling asleep.3 Signs of approaching death include prolonged periods of sleeping, increasing weakness, changes in breathing patterns (e.g., Cheyne-Stokes respiration, periods of apnea), and loss of bowel and bladder control.3 Reduced circulation to the extremities often causes them to feel cold to the touch.3 While one study indicated that mean scores for pain, nausea, anxiety, and depression remained relatively stable in the 6 months prior to death 37, other research suggests that pain in terminal cancer patients is often not adequately managed.18 Unlike acute, sudden deaths, cancer often involves a protracted and complex dying process characterized by chronic, moderate to severe physical pain.6 This pain is not static but can be nociceptive, neuropathic, or breakthrough, and is often accompanied by other debilitating physical symptoms like fatigue and dyspnea.37 The concept of "total pain" is highly relevant here, as psychological and existential distress are deeply intertwined with physical symptoms.8 While unconsciousness may precede death 3, the journey to that point can be very long, and patients may experience fluctuating levels of consciousness, meaning periods of awareness and pain perception are possible throughout the terminal phase.18 Therefore, quantifying pain in cancer deaths necessitates assessing a cumulative, multifaceted suffering experience over an extended period, not just the immediate moments of death. The pain at the very moment of death might be mitigated by unconsciousness, but the preceding weeks or months often involve substantial conscious suffering. This highlights the paramount importance of comprehensive, individualized palliative care to manage complex symptoms and address holistic distress, aiming to improve quality of life throughout the entire dying trajectory.8 2.4. Sepsis Mechanisms of Systemic Inflammatory Response and Organ Dysfunction Sepsis is a life-threatening condition where the body's response to an infection becomes dysregulated, causing widespread inflammation that damages its own tissues and organs.4 In essence, the infection-fighting processes effectively "turn on the body".4 This systemic inflammatory response leads to vital organs such as the brain, heart, kidneys, lungs, and liver receiving insufficient blood flow, atypical blood clotting, and subsequent tissue damage or destruction.4 Sepsis can progress to septic shock, which is characterized by a dramatic and severe drop in blood pressure.4 This profound hypotension further compromises organ perfusion and significantly increases the risk of death, with mortality rates for septic shock ranging from 30% to 40%.4 The pathophysiological progression moves from a systemic inflammatory response syndrome (SIRS) to multi-organ dysfunction syndrome (MODS) before culminating in death.42 This involves a complex interplay of pro-inflammatory and anti-inflammatory mediators, leading to increased capillary permeability and microvascular injury throughout the body.42 Pain and Discomfort Progression Initial symptoms of sepsis can be non-specific, resembling a severe flu, including fever, chills (sometimes with rigors, or teeth-chattering shaking), nausea, vomiting, fatigue, and lethargy.43 Pain can be present, often localized to the site of the initial infection (e.g., abdominal pain from a urinary tract infection, labored breathing from pneumonia, or warmth, redness, and pain from cellulitis).43 Widespread muscle and joint pain can also develop as the systemic inflammation progresses.41 As sepsis worsens, mental status changes become prominent, progressing from confusion and agitation to delirium, lethargy, and eventually unconsciousness.4 Patients may "talk nonsense" or become "combative" due to septic encephalopathy, a brain dysfunction caused by the systemic infection.43 Other critical signs include fast, shallow breathing (tachypnea), a rapid heart rate (tachycardia), and dangerously low blood pressure.4 As blood pressure drops severely, patients become increasingly unresponsive and eventually unconscious.43 Organ systems begin to shut down in a sequence, typically kidneys first (leading to reduced urine output and waste buildup in the blood), then the liver (potentially causing jaundice), and the heart (leading to myocardial dysfunction).42 Breathing patterns worsen, progressing to Kussmaul (deep, labored breathing) and Cheyne-Stokes respiration (cyclic breathing with periods of apnea).43 Sepsis is characterized by widespread systemic inflammation and multi-organ failure 4, rather than a single, localized source of pain, although initial infection sites can be painful.43 The pain experienced is often diffuse, a consequence of systemic breakdown. Crucially, as the condition progresses towards death, there is a consistent and significant decline in mental status, leading to confusion, delirium, lethargy, and ultimately unconsciousness.4 This progressive loss of consciousness means that while the physiological processes leading to death are severe, the conscious perception of pain in the final moments is likely significantly mitigated or absent. In many cases, the final moments of death from sepsis are described as relatively peaceful, as the patient is often deeply unconscious or "asleep" with labored breathing before cardiac arrest.43 For sepsis-related deaths, the quantification of pain in the immediate terminal phase is complex. While there is significant suffering from organ dysfunction and inflammation, the declining mental status often leads to a state where the individual is no longer consciously perceiving extreme pain. This suggests that the experience of death from sepsis, while physiologically devastating, may be less consciously agonizing than often assumed, particularly in its very final stages. 2.5. Traumatic Injuries (Blunt Force, Penetrating, Internal Hemorrhage) Mechanisms of Injury and Death Trauma is defined as sudden tissue injury resulting from violence or accident, which triggers the body's homeostatic responses.46 Traumatic injuries are broadly categorized into penetrating, blunt, and deceleration trauma.46 ⦁ Penetrating Trauma: Occurs when an object pierces the skin, causing direct tissue destruction and significant blood loss.47 High-velocity penetrating wounds are often immediately fatal.47 A critical and feared consequence is hypovolemic shock, which results from massive blood loss leading to decreased circulating blood volume and reduced perfusion of vital organs such such as the kidneys, brain, heart, liver, and colon.46 This manifests clinically as hypotension (low blood pressure), tachycardia (rapid heart rate), and cold skin.46 ⦁ Blunt Force Trauma: Involves a forceful impact without penetration of the body's surface.48 It can cause a wide range of injuries including contusions (bruises), concussions, abrasions, lacerations, internal or external hemorrhages, and bone fractures.49 Blunt trauma to the head, leading to Traumatic Brain Injury (TBI), and/or severe blood loss are the most common causes of death from blunt force injury.49 TBI is a significant cause of mortality.49 ⦁ Internal Hemorrhage: Can result from various traumatic events, including car accidents, falls, or broken bones (e.g., femur fractures can cause significant blood loss).52 It can also be caused by ruptured aneurysms or complications from surgery.52 Symptoms include severe pain (abdominal, chest, or joint pain depending on the site of bleeding), dizziness, profound weakness, low blood pressure, and signs of shock.52 At the cellular level, traumatic injury leads to a loss of cellular integrity and function, activating cell death mechanisms such as necroptosis.46 Acute Pain and Consciousness Loss Acute traumatic injuries are characterized by sudden, severe pain at the moment of impact or injury.52 A high percentage, specifically 60-70%, of emergency room patients with trauma report experiencing moderate to severe pain.54 In cases of severe blunt force trauma, particularly to the head, loss of consciousness can occur very rapidly due to brain swelling and herniation.48 Death can be instantaneous if the skull fracture penetrates the brain, or it can occur hours to days later with slower bleeds.56 Penetrating injuries, especially to the chest, cause intense pain, difficulty breathing, and rapid physiological deterioration, including a fast heart rate and low blood pressure, often leading to collapse and loss of consciousness.52 For immediate trauma deaths, those occurring within minutes of the injury, the cause is typically severe and non-survivable injuries to the central nervous and cardiovascular systems.57 Brain injury accounts for approximately 50% of these immediate deaths, while hemorrhage, often in the chest or abdomen, accounts for about 31%.57 Fatal traumatic injuries present a critical distinction in the experience of pain. The initial impact or injury is characterized by immediate, excruciating pain.52 However, in many truly fatal and immediate traumatic events, such as severe head trauma or massive hemorrhage, unconsciousness occurs very rapidly, often within minutes or seconds, due to severe brain damage or hypovolemic shock.46 This suggests that while the initial conscious experience of pain is intense, its duration in the moments leading directly to death is often extremely brief. Conversely, if the injury is not immediately fatal but leads to a slower decline or chronic issues, such as a slow brain bleed 56 or the development of post-traumatic stress disorder (PTSD) from inadequate pain control 54, pain can persist over a longer period. When attempting to quantify pain during traumatic death, it is crucial to differentiate between the intense, but often very short, period of conscious pain immediately following the injury and the subsequent state of unconsciousness. The most significant conscious suffering likely occurs at the moment of impact and for a very brief period thereafter, before physiological collapse renders the individual unaware. This also underscores the importance of immediate pain management in trauma care, not just for comfort but also to mitigate the stress response.54 2.6. Asphyxiation (Suffocation, Strangulation, Hanging, Drowning) Mechanisms of Oxygen Deprivation Asphyxia, or suffocation, occurs when the body does not receive sufficient oxygen, leading to hypoxia (low oxygen levels) and ultimately death.59 This deprivation can result from direct airway obstruction, as seen in choking, suffocation, strangulation, or hanging, or from environmental factors where oxygen is scarce or displaced by other gases, such as in airtight spaces or due to chemical asphyxiants like carbon monoxide or cyanide.59 ⦁ Strangulation/Hanging: These involve external compression of the neck, which can obstruct blood flow through the carotid arteries and jugular veins, and/or block the airway (trachea).60 This leads to cerebral hypoxemia, a severe lack of oxygen to the brain, and rapid neuronal death.62 Loss of consciousness can occur very quickly, ranging from seconds to approximately 2.5 minutes.63 ⦁ Suffocation/Smothering: This occurs when something heavy covers the face or chest, physically preventing breathing, or when an individual is in a confined, airtight space where oxygen is depleted.59 ⦁ Drowning: Defined as respiratory impairment resulting from submersion in a liquid medium.65 The physiological process typically includes an initial period of voluntary breath-holding, followed by involuntary water aspiration, and often a laryngospasm—a reflex closure of the vocal cords that can prevent water from entering the lungs, sometimes referred to as "dry drowning".65 Regardless of whether water enters the lungs, the ultimate consequence is severe hypoxia, which profoundly impacts the brain, heart, and other tissues, leading to respiratory arrest followed by cardiac arrest.65 Immersion in cold water can induce a "cold shock" response, causing involuntary gasping and hyperventilation, and can lead to hypothermia, which initially offers some protection by slowing metabolism but also causes physical incapacitation and loss of consciousness.65 Pain and Suffering Progression, Consciousness Timeline ⦁ Strangulation: Victims typically experience initial severe pain in the neck, coupled with extreme difficulty and pain during breathing and swallowing.63 Other symptoms include eye problems (such as seeing stars or blurred vision), hearing disturbances (ringing or popping noises), and a terrifying sense of impending death.73 This is followed by unconsciousness and often loss of bladder or bowel control.73 The general clinical sequence is described as severe pain, followed by unconsciousness, and then brain death.63 Notably, death can occur even without visible external injuries.74 ⦁ Hanging: While judicial hanging aims for instantaneous death via spinal fracture, other forms of hanging, particularly non-judicial ones, are often described as a "slow, painful, and messy method".75 ⦁ Drowning: The process begins with intense panic and "air hunger".66 During the voluntary breath-hold phase, individuals report "unbearable pain" and a sensation that their "head is about to explode" due to the buildup of carbon dioxide.77 This is followed by an involuntary gasp, leading to the inhalation of water (in "wet drowning") or continued laryngospasm ("dry drowning"), and then rapid loss of consciousness.77 Consciousness is typically lost within 2 minutes of submersion, with irreversible brain injury occurring within 4-6 minutes.76 Cold water immersion can induce an "intense cold pain" 67 during the initial cold shock response. The research consistently describes an initial period of intense, conscious suffering across various forms of asphyxiation. This suffering is characterized by severe physical pain (e.g., neck pain, the "exploding head" sensation), extreme air hunger, and profound panic and terror.63 However, a critical commonality is the rapid onset of unconsciousness, typically within seconds to a few minutes, due to severe cerebral anoxia.63 This means that while the initial phase is agonizing, the duration of conscious suffering in the immediate terminal phase is relatively brief, as the physiological mechanism quickly leads to a state where pain perception ceases. For deaths by asphyxiation, the quantification of pain must acknowledge the peak intensity of suffering during the initial conscious struggle, but also the rapid transition to unconsciousness. This implies that the most severe conscious pain is short-lived, although the psychological terror of impending death is immense during that brief period. The specific sensory experience, such as the "intense cold pain" in cold water drowning 67, adds another layer to this complex suffering. 2.7. Severe Burns Mechanisms of Injury and Death Burn injuries result from contact with various heat sources, including high temperature, electricity, chemicals, friction, and radiation.78 Cellular damage begins at temperatures over 40°C, with cellular repair mechanisms failing above 45°C, leading to cell death.79 At 60°C, blood vessels thrombose (clot), and tissue becomes necrotic.79 Death from severe burns, particularly when the burn wound exceeds 20% of the total body surface area, is often due to a complex cascade known as "burn wound syndrome".79 Key components of this syndrome include: ⦁ Massive Fluid and Electrolyte Loss: This leads to widespread oedema (swelling) and hypovolemic shock (a life-threatening condition caused by severe fluid loss) if not aggressively managed with fluid resuscitation.79 ⦁ Wound Infection: The extensive damaged skin surface represents a large area highly susceptible to rapid colonization by skin and gut bacteria, leading to a high risk of septic shock.78 ⦁ Hypermetabolic State: The body enters a severe catabolic (tissue-breaking down) state, resulting in pronounced weight loss.79 ⦁ Multiple Organ Dysfunction/Failure (MODS/MOF): This can include pulmonary insufficiency (due to airway damage, hypoxia, or respiratory failure), renal insufficiency (from dehydration and the direct effects of myoglobin and hemoglobin metabolism), and gastrointestinal tract issues (such as dilatation, ileus, and ulceration during recovery).79 The systemic inflammatory response syndrome (SIRS), where pro-inflammatory mediators overwhelm the body's protective mechanisms, is a common endpoint and a major cause of mortality in critical burn care.79 Pain Intensity and Nature Burn injury is widely recognized as inducing "the most intense pain".81 The severity of pain varies significantly among patients and fluctuates widely over time in each individual, with peak intensity often experienced during therapeutic procedures such as dressing changes.81 These procedures are frequently described as very painful, often requiring opioid and anxiety medications.81 Full-thickness burns, similar to third-degree burns, destroy nerve endings within the deepest burn area, meaning these specific areas may not feel pain.80 However, the surrounding partial-thickness burn areas and deeper underlying tissues (muscles, nerves, bones) remain intensely painful.80 Burn pain has both inflammatory and neuropathic components.81 Acute neuropathic pain, resulting from damage to nerve endings, is a significant component of burn injury-induced pain (BIP) and is often under-recognized and under-treated.81 Chronic burn pain can persist for long periods, even after complete wound healing and hospital discharge, leading to long-term disability and neurological dysfunction.81 This chronic pain can involve non-burned areas as well.81 Unlike many other acute causes of death where unconsciousness rapidly mitigates pain, severe burns are characterized by protracted, intense, and multifaceted pain.80 Even if the deepest burn areas are insensate due to nerve destruction, the surrounding areas, the underlying tissues, and the essential, repeated medical procedures (e.g., dressing changes) are excruciatingly painful.80 The progression to death from severe burns is often due to complications like septic shock or multi-organ failure 79, which themselves involve pain and declining consciousness. However, the underlying burn pain, including neuropathic components, can persist and contribute to the overall suffering throughout this prolonged course. This is a scenario where conscious suffering can be very significant and sustained over days or weeks. Quantifying pain in burn deaths requires acknowledging not only the initial severe injury but also the continuous, evolving, and often agonizing pain experience throughout the treatment and complication phases. This includes acute, inflammatory, and neuropathic pain components, which can persist until the moment of death. This highlights the critical and ongoing need for aggressive, individualized, and multi-modal pain management strategies throughout the entire patient journey, up to the terminal phase.
3. Scientific Quantification of Pain: Methodologies and Limitations 3.1. Overview of Unidimensional Pain Scales (NRS, VAS) and their application Unidimensional pain scales are designed to measure the intensity of pain. Among these, the Numeric Rating Scale (NRS) and the Visual Analog Scale (VAS) are widely recognized and frequently used in clinical practice.15 ⦁ Numeric Rating Scale (NRS): The NRS is a widely utilized unidimensional scale where patients rate their pain intensity on a numerical scale, typically from 0 to 10.6 On this scale, 0 represents "no pain," and 10 signifies "the worst pain imaginable".6 It is easy to administer, either verbally or in writing, making it a practical tool in various clinical environments.15 The NRS has demonstrated good correlation with other pain scales and is sensitive enough to detect changes in pain intensity following treatment.15 ⦁ Visual Analog Scale (VAS): The VAS is another unidimensional scale that measures pain intensity, typically ranging from 0 to 10.15 It is presented as a line where patients mark their perceived pain intensity, from "no pain" at one end to "the worst imaginable pain" at the other.15 This mark is then measured to derive a numerical value.15 The VAS is effective for capturing pain intensity at a specific moment and is considered a dependable tool for pain measurement.15 While NRS and VAS are practical and reliable for conscious, verbally communicative patients 15, their fundamental reliance on self-report means their utility diminishes significantly as a patient's consciousness fades or their ability to communicate verbally becomes impaired.15 The very mechanism of "self-reporting" pain, which is the cornerstone of these scales, becomes impossible in such circumstances. This creates a critical gap in quantifying pain in the final moments of life for many patients. These scales are valuable for assessing pain leading up to the terminal phase, especially in chronic conditions like cancer or post-stroke pain, where patients may still be communicative. However, for the immediate moments of death, particularly in sudden events or when patients become unconscious, these tools are largely inadequate, reinforcing the challenge of obtaining a direct "scientific quantification" of pain in the most critical phase of dying. 3.2. Multidimensional Pain Scales (MPQ, BPI) for comprehensive assessment Beyond simple intensity, pain assessment can delve into the qualitative and comprehensive aspects of the experience using multidimensional scales. ⦁ McGill Pain Questionnaire (MPQ): The MPQ is a comprehensive, multidimensional pain assessment tool that employs 78 pain descriptors categorized into sensory, affective, and evaluative dimensions.15 It is designed to provide a detailed qualitative and quantitative understanding of pain, helping to distinguish various pain syndromes effectively.15 The MPQ has demonstrated high reliability and can predict associated issues such as anxiety and depression, aligning well with the concept of "total pain".15 ⦁ Brief Pain Inventory (BPI): The BPI is another multidimensional scale that not only assesses pain severity (often categorized as mild, moderate, or severe) but also evaluates how pain interferes with daily activities and overall quality of life.15 Multidimensional scales like the MPQ and BPI are conceptually superior to unidimensional scales because they capture the complex, subjective, and holistic experience of pain, including its emotional and functional impacts.6 This aligns perfectly with the "total pain" concept 7 and the broader understanding of suffering at the end of life. However, similar to NRS and VAS, these tools rely heavily on the patient's ability to articulate, describe, and reflect on their experience. This crucial dependency means they become impractical or impossible to use as a patient's cognitive function declines or they lose consciousness in the terminal phase. While these tools are invaluable for a comprehensive understanding of suffering in terminally ill patients who are still able to communicate, they are limited in providing "scientific quantification" of pain during the immediate dying process when communication is compromised. Their primary utility lies in informing palliative care strategies before the final stages of unconsciousness. 3.3. Pain Assessment in Cognitively Impaired and Non-Verbal Patients (PAINAD, Behavioral Scales, Physiological Indicators) Assessing pain in patients with cognitive impairments, such as delirium or dementia, or those who are otherwise non-verbal, presents a significant challenge. For these populations, specialized tools and indirect measures are utilized. ⦁ PAINAD (Pain Assessment in Advanced Dementia) Scale: This scale is specifically designed for patients with cognitive impairments.82 It scores pain from 0-10 (where 1-3 indicates mild pain, 4-6 moderate, and 7-10 severe) based on observable behaviors such as breathing patterns, negative vocalizations (e.g., moaning, groaning), facial expressions (e.g., grimacing), body language (e.g., rigidity, restlessness), and consolability.82 ⦁ Behavioral Scales: Other validated behavioral scales, including the Behavior Pain Scale and the Critical-Care Pain Observational Tool (CPOT), are employed for assessing pain in critically ill and non-verbal patients across various clinical settings.19 These tools rely on systematic observation of a patient's reactions and behaviors. ⦁ Physiological Indicators: While physiological indicators are explored, they present significant limitations. Isolated fluctuations in vital signs, such as heart rate or blood pressure, are considered poor predictors of pain and should be viewed as adverse events associated with severe pain rather than direct pain measures.19 More advanced physiological monitoring techniques are emerging, including pupillometry (measuring pupillary reflex), the Analgesia Nociception Index (ANI), and the Nociception Level Index (NLI).19 These technologies use complex algorithms and biofeedback to infer nociception, the neural process of encoding noxious stimuli. Additionally, artificial intelligence for facial expression analysis is being developed as a potential tool for pain detection and intensity analysis at the bedside.19 Key observable signs of pain in non-verbal patients that clinicians look for include mood changes (e.g., agitation, restlessness), refusal of food or drink, withdrawal, avoidance of eye contact, general signs of distress or discomfort, body tension or rigidity, and grimacing or frowning.18 When a patient loses the ability to self-report pain due to cognitive impairment or unconsciousness, clinicians must rely on proxies—observable behaviors and physiological responses.18 While tools like PAINAD and CPOT are validated for these populations, they are inherently indirect measures. For instance, vital sign changes can be caused by the underlying disease process itself, not solely pain.19 Behavioral signs are interpretations of external cues, not direct access to the internal subjective experience.12 Even advanced physiological monitors provide an "index of nociception" rather than a direct measure of conscious pain. This highlights the profound difficulty in achieving precise "scientific quantification" of pain in the unconscious or non-verbal dying patient. While these tools are indispensable for clinical management and upholding ethical obligations to alleviate suffering 17, they represent an inference of suffering rather than a direct, objective measurement. The "scientific" aspect here pertains to the reliability and validity of the assessment method in inferring pain, rather than a definitive numerical value of the subjective experience itself. This underscores the ongoing challenge and the need for continued research in this area. 3.4. Challenges in Objective Measurement and the Subjectivity of Pain The fundamental challenge in pain assessment lies in the fact that the personal experience of pain is "fundamentally unobservable" by others.12 This inherent subjectivity means that while clinicians and researchers must rely on observations and measures to assess and infer pain, these methods often overlook crucial attributes of the subjective experience, such as personal context and meaning, which profoundly shape an individual's perception of pain.12 This creates a scientific paradox: how can something inherently subjective be objectively quantified? While various pain scales and physiological indicators provide numerical data or behavioral observations, these are ultimately proxies for an internal state that cannot be directly measured.12 Current models of pain assessment often fail to adequately integrate this subjectivity, leading to a reliance on numeric forms of assessment that may miss essential aspects of the pain experience.12 This ambiguity can lead to uncertainty for clinicians when faced with discrepancies between different forms of assessment, making it difficult to decide which findings should be most relied upon as indicators for the non-observable pain experience.12 Therefore, any numerical "quantification" of pain at the end of life must be understood as an approximation or an inference, rather than a direct, definitive readout of the subjective experience. The scientific rigor in this field is applied to the reliability and validity of the assessment methods used to infer pain, rather than to a direct numerical value of the subjective experience itself. This also underscores the ethical imperative to provide pain relief based on observed signs of distress, even when precise subjective quantification is impossible.17 Validating pain reports and showing compassion are crucial, as a failure to do so can increase patient distress, degrade the therapeutic relationship, and undermine hope for improvement.12 The experience of pain is a function of the whole person, influenced by environmental and contextual factors, and this complex interplay must be considered in assessment and care.12
4. Conclusions: The Nuanced Landscape of Pain at the End of Life The scientific examination of pain and suffering across diverse mortality pathways reveals a complex and nuanced landscape. A precise, universal quantification of pain at the moment of death is inherently limited due to the subjective nature of pain and the rapid physiological changes that often lead to a loss of consciousness in the terminal phase. The analysis demonstrates that the experience of suffering varies significantly depending on the cause of death. Some deaths, such as those resulting from acute traumatic injuries, hemorrhagic strokes, or certain forms of asphyxiation, are characterized by an initial period of intense, conscious physical pain and profound terror, which is often brief before unconsciousness supervenes due to rapid neurological or circulatory collapse. In these scenarios, the most severe conscious suffering is short-lived, even if the preceding moments are agonizing. Conversely, deaths from conditions like advanced cancer, severe burns, or sepsis often involve a protracted and multifaceted period of suffering. Here, pain is a significant and persistent component of the dying process, encompassing not only physical discomfort (which can be chronic, nociceptive, or neuropathic) but also profound psychological, social, and existential distress. While unconsciousness may eventually precede death in these cases, the journey to that point can span days, weeks, or even months, during which conscious suffering can be substantial and sustained. The progressive decline in mental status in conditions like sepsis can, in the final moments, mitigate conscious pain, leading to a more "peaceful" transition, but this does not negate the suffering experienced prior to that state. The concept of "total pain" is paramount in understanding the end-of-life experience, emphasizing that suffering extends far beyond physical sensations to include emotional, social, and spiritual dimensions. Current pain assessment methodologies, while valuable for conscious and communicative patients, face significant limitations in providing a direct, objective quantification of pain as patients become non-verbal or unconscious. Behavioral scales and physiological indicators serve as necessary proxies, allowing clinicians to infer suffering and guide compassionate care, but they are not direct windows into the subjective experience. Therefore, the scientific pursuit in this field should focus not on achieving a single, definitive numerical "pain score" at the moment of death, which is inherently elusive. Instead, the emphasis must be on improving comprehensive assessment methods for non-communicative patients and, crucially, on ensuring compassionate, individualized palliative care that addresses all forms of suffering—physical, psychological, social, and spiritual—throughout the entire dying trajectory. The goal is to alleviate distress and enhance the quality of life for individuals as they approach their end, recognizing the profound and multifaceted nature of their experience. 참고 자료
5. 10 Leading Causes of Death in the United States - Healthline, 7월 26, 2025에 액세스, https://www.healthline.com/health/leading-causes-of-death
6. Underlying and contributing causes of mortality from CDC WONDER—Insights for researchers - PMC, 7월 26, 2025에 액세스, https://pmc.ncbi.nlm.nih.gov/articles/PMC11782113/
7. How Does Cancer Kill You? - Verywell Health, 7월 26, 2025에 액세스, https://www.verywellhealth.com/how-does-cancer-kill-you-5096986
8. Sepsis - Symptoms & causes - Mayo Clinic, 7월 26, 2025에 액세스, https://www.mayoclinic.org/diseases-conditions/sepsis/symptoms-causes/syc-20351214
9. Pain in the ICU – The fifth sign, not the fifth element - Medicina Intensiva, 7월 26, 2025에 액세스, https://www.medintensiva.org/es-pain-in-icu-the-articulo-S0210569116302091
10. Cancer Pain (PDQ®) - NCI, 7월 26, 2025에 액세스, https://www.cancer.gov/about-cancer/treatment/side-effects/pain/pain-hp-pdq
11. End-of-Life Evaluation and Management of Pain - StatPearls - NCBI Bookshelf, 7월 26, 2025에 액세스, https://www.ncbi.nlm.nih.gov/books/NBK568753/
12. Palliative Care: Easing Psychological Distress - Number Analytics, 7월 26, 2025에 액세스, https://www.numberanalytics.com/blog/palliative-care-psychological-distress
13. Coping with Existential Distress in Terminal Illness - Number Analytics, 7월 26, 2025에 액세스, https://www.numberanalytics.com/blog/existential-distress-terminal-illness-hospice-care
14. FF #319 Existential Suffering - Part 1: Definition and Diagnosis | Palliative Care Network of Wisconsin, 7월 26, 2025에 액세스, https://www.mypcnow.org/fast-fact/existential-suffering-part-1-definition-and-diagnosis/
15. Psychological aspects of suffering in illness and dying - Via Medica Journals, 7월 26, 2025에 액세스, https://journals.viamedica.pl/advances_in_palliative_medicine/article/viewFile/29321/24074
16. The Multimodal Assessment Model of Pain: A Novel Framework for Further Integrating the Subjective Pain Experience Within Research and Practice - PubMed Central, 7월 26, 2025에 액세스, https://pmc.ncbi.nlm.nih.gov/articles/PMC6382036/
17. Chronic Pain Patients and the Biomedical Model of Pain - AMA Journal of Ethics, 7월 26, 2025에 액세스, https://journalofethics.ama-assn.org/article/chronic-pain-patients-and-biomedical-model-pain/2013-05
18. Cancer Pain (PDQ®) - PDQ Cancer Information Summaries - NCBI ..., 7월 26, 2025에 액세스, https://www.ncbi.nlm.nih.gov/books/NBK65949/
19. Understanding the Pain Scale for Back Pain, 7월 26, 2025에 액세스, https://ptnear.com/understanding-the-pain-scale-for-back-pain/
20. PAIN INTENSITY SCALES COMPARISON IN PATIENT WITH ABDOMINAL PAIN - Psychiatria Danubina, 7월 26, 2025에 액세스, https://www.psychiatria-danubina.com/UserDocsImages/pdf/dnb_vol29_noSuppl%204/dnb_vol29_noSuppl%204_127.pdf
21. Understanding the dying process - WA Health, 7월 26, 2025에 액세스, https://www.health.wa.gov.au/~/media/Files/Corporate/general%20documents/Palliative/Patient%20information/UnderstandingTheDyingProcess.pdf
22. Does Dying Hurt? Managing End of Life Pain - Verywell Health, 7월 26, 2025에 액세스, https://www.verywellhealth.com/is-death-painful-managing-end-of-life-pain-2249014
23. Acute pain in the critically ill patient: revisiting the ... - SciELO Brasil, 7월 26, 2025에 액세스, https://www.scielo.br/j/brjp/a/P7KKFMNqTg6bdt55wM8m6Cj/
24. Heart attack - Symptoms & causes - Mayo Clinic, 7월 26, 2025에 액세스, https://www.mayoclinic.org/diseases-conditions/heart-attack/symptoms-causes/syc-20373106
25. Heart Attack: Symptoms & Treatment - Cleveland Clinic, 7월 26, 2025에 액세스, https://my.clevelandclinic.org/health/diseases/16818-heart-attack-myocardial-infarction
26. Sudden cardiac arrest - Symptoms and causes - Mayo Clinic, 7월 26, 2025에 액세스, https://www.mayoclinic.org/diseases-conditions/sudden-cardiac-arrest/symptoms-causes/syc-20350634
27. Know the Signs, Help Save a Life: Sudden Cardiac Arrest vs. Heart Attack - UC Health, 7월 26, 2025에 액세스, https://www.uchealth.com/en/media-room/articles/know-the-signs-help-save-a-life-sudden-cardiac-arrest-vs-heart-attack
28. Mechanism of death: there's more to it than sudden cardiac arrest ..., 7월 26, 2025에 액세스, https://pmc.ncbi.nlm.nih.gov/articles/PMC6006107/
29. Heart Attack (Myocardial Infarction) - Cedars-Sinai, 7월 26, 2025에 액세스, https://www.cedars-sinai.org/health-library/diseases-and-conditions/h/heart-attack-myocardial-infarction.html
30. Myocardial infarction - Wikipedia, 7월 26, 2025에 액세스, https://en.wikipedia.org/wiki/Myocardial_infarction
31. Cell Death Mechanisms in Stroke and Novel Molecular and Cellular ..., 7월 26, 2025에 액세스, https://pmc.ncbi.nlm.nih.gov/articles/PMC6251049/
32. Hemorrhagic Stroke - Symptoms & Treatment | Mount Sinai - New York, 7월 26, 2025에 액세스, https://www.mountsinai.org/locations/cerebrovascular-center/conditions/stroke/hemorrhagic-stroke
33. Cerebral Hemorrhage | UTHealth Houston Neurosciences, 7월 26, 2025에 액세스, https://med.uth.edu/neurosciences/cerebral-hemorrhage/
34. Intracerebral Hemorrhage - AANS, 7월 26, 2025에 액세스, https://www.aans.org/patients/conditions-treatments/intracerebral-hemorrhage/
35. Stroke - Symptoms and causes - Mayo Clinic, 7월 26, 2025에 액세스, https://www.mayoclinic.org/diseases-conditions/stroke/symptoms-causes/syc-20350113
36. Hemorrhagic Stroke, 7월 26, 2025에 액세스, https://www.stroke.org/en/about-stroke/types-of-stroke/hemorrhagic-strokes-bleeds
37. The Basics About Brain Bleeds - Lehigh Valley Health Network, 7월 26, 2025에 액세스, https://www.lvhn.org/news/basics-about-brain-bleeds
38. Stroke Pain - Chronic Stroke Pain | Stanford Health Care, 7월 26, 2025에 액세스, https://stanfordhealthcare.org/medical-conditions/brain-and-nerves/chronic-pain/types/stroke-pain.html
39. Following a stroke, pain is common but can be managed | American Heart Association, 7월 26, 2025에 액세스, https://www.heart.org/en/news/2024/07/09/following-a-stroke-pain-is-common-but-can-be-managed
40. Cancer - World Health Organization (WHO), 7월 26, 2025에 액세스, https://www.who.int/news-room/fact-sheets/detail/cancer
41. Last Days of Life (PDQ®)–Health Professional Version - National Cancer Institute, 7월 26, 2025에 액세스, https://www.cancer.gov/about-cancer/advanced-cancer/caregivers/planning/last-days-hp-pdq
42. When death is near: Signs and symptoms - Hospice Foundation of America, 7월 26, 2025에 액세스, https://hospicefoundation.org/when-death-is-near-signs-and-symptoms/
43. Symptom Relief for the Dying Patient - Special Subjects - MSD Manual Professional Edition, 7월 26, 2025에 액세스, https://www.msdmanuals.com/professional/special-subjects/the-dying-patient/symptom-relief-for-the-dying-patient
44. Chronic Pain and Mental Health - HelpGuide.org, 7월 26, 2025에 액세스, https://www.helpguide.org/wellness/health-conditions/chronic-pain-and-mental-health
45. Sepsis: Symptoms, Causes, Treatment & Prevention - Cleveland Clinic, 7월 26, 2025에 액세스, https://my.clevelandclinic.org/health/diseases/12361-sepsis
46. Septic Shock - StatPearls - NCBI Bookshelf, 7월 26, 2025에 액세스, https://www.ncbi.nlm.nih.gov/books/NBK430939/
47. Need help with fleshing out the details— how does the process of ..., 7월 26, 2025에 액세스, https://www.reddit.com/r/Writeresearch/comments/1kiil5v/need_help_with_fleshing_out_the_details_how_does/
48. Post-Sepsis Syndrome, 7월 26, 2025에 액세스, https://www.sepsis.org/sepsis-basics/post-sepsis-syndrome/
49. How Long Does it Take to Die From Sepsis?, 7월 26, 2025에 액세스, https://www.nursinghomelawcenter.org/news/how-long-does-it-take-to-die-from-sepsis/
50. Physiology, Trauma - StatPearls - NCBI Bookshelf, 7월 26, 2025에 액세스, https://www.ncbi.nlm.nih.gov/books/NBK538478/
51. Penetrating Abdominal Trauma - StatPearls - NCBI Bookshelf, 7월 26, 2025에 액세스, https://www.ncbi.nlm.nih.gov/books/NBK459123/
52. Traumatic Injury: What It Is, Examples, Causes & Symptoms - Cleveland Clinic, 7월 26, 2025에 액세스, https://my.clevelandclinic.org/health/articles/traumatic-injury
53. Blunt trauma - Wikipedia, 7월 26, 2025에 액세스, https://en.wikipedia.org/wiki/Blunt_trauma
54. Traumatic Brain Injury | Johns Hopkins Medicine, 7월 26, 2025에 액세스, https://www.hopkinsmedicine.org/health/conditions-and-diseases/traumatic-brain-injury
55. Traumatic Brain Injury (TBI) | National Institute of Neurological Disorders and Stroke, 7월 26, 2025에 액세스, https://www.ninds.nih.gov/health-information/disorders/traumatic-brain-injury-tbi
56. Internal Bleeding: Symptoms, Diagnosis, and Treatment - Healthline, 7월 26, 2025에 액세스, https://www.healthline.com/health/internal-bleeding
57. Signs and Symptoms of Internal Bleeding (Internal Hemorrhage) - GoodRx, 7월 26, 2025에 액세스, https://www.goodrx.com/health-topic/hematology/internal-bleeding-signs
58. Acute Traumatic Pain in the Emergency Department - MDPI, 7월 26, 2025에 액세스, https://www.mdpi.com/2079-9721/11/1/45
59. Chest injuries - symptoms, causes and treatments - Healthdirect, 7월 26, 2025에 액세스, https://www.healthdirect.gov.au/chest-injuries
60. Blunt force trauma to the head : r/Writeresearch - Reddit, 7월 26, 2025에 액세스, https://www.reddit.com/r/Writeresearch/comments/1kasvr1/blunt_force_trauma_to_the_head/
61. Timing and causes of death after injuries - PMC - PubMed Central, 7월 26, 2025에 액세스, https://pmc.ncbi.nlm.nih.gov/articles/PMC3603725/
62. Post-traumatic stress disorder (PTSD) - Symptoms and causes - Mayo Clinic, 7월 26, 2025에 액세스, https://www.mayoclinic.org/diseases-conditions/post-traumatic-stress-disorder/symptoms-causes/syc-20355967
63. Asphyxia: Types, Causes, Symptoms, Risk Factors & Prevention, 7월 26, 2025에 액세스, https://www.webmd.com/first-aid/asphyxia-overview
64. Asphyxial Deaths: A Comprehensive Guide - Number Analytics, 7월 26, 2025에 액세스, https://www.numberanalytics.com/blog/ultimate-guide-asphyxial-deaths-forensic-pathology
65. The Many Implications of Asphyxiation - Godoy Medical Forensics, 7월 26, 2025에 액세스, https://godoymedical.net/the-many-implications-of-asphyxiation/
66. Strangulation Injuries - StatPearls - NCBI Bookshelf, 7월 26, 2025에 액세스, https://www.ncbi.nlm.nih.gov/books/NBK459192/
67. a review of 300 attempted strangulation cases part ii: clinical evaluation of the surviving victim - City of Bloomington, Indiana, 7월 26, 2025에 액세스, https://bloomington.in.gov/sites/default/files/2017-09/Review%20of%20300%20attempted%20Strangulation%20Cases_Part%20II.pdf
68. FATALITY BY STRANGULATION - NJ.gov, 7월 26, 2025에 액세스, https://www.nj.gov/dcf/news/reportsnewsletters/taskforce/Fatality-by-Strangulation-Report_2019.pdf
69. Physiology Of Drowning: A Review, 7월 26, 2025에 액세스, https://journals.physiology.org/doi/abs/10.1152/physiol.00002.2015
70. Drowning - Injuries; Poisoning - MSD Manual Professional Edition, 7월 26, 2025에 액세스, https://www.msdmanuals.com/professional/injuries-poisoning/drowning/drowning
71. Physiology Of Drowning: A Review - Diving & ROV specialists, 7월 26, 2025에 액세스, https://diving-rov-specialists.com/index_htm_files/scient-c_158-Physio-of-drowning.pdf
72. Drowning | EBSCO Research Starters, 7월 26, 2025에 액세스, https://www.ebsco.com/research-starters/health-and-medicine/drowning
73. What Are the Signs of Dry Drowning (Secondary Drowning)? - SI Parent, 7월 26, 2025에 액세스, https://www.siparent.com/what-are-the-signs-of-dry-drowning-secondary-drowning/
74. Dry Drowning & Secondary Drowning: Symptoms and Warning Signs - WebMD, 7월 26, 2025에 액세스, https://www.webmd.com/children/features/secondary-drowning-dry-drowning
75. Drowning - Wikipedia, 7월 26, 2025에 액세스, https://en.wikipedia.org/wiki/Drowning
76. Physiology Of Drowning: A Review, 7월 26, 2025에 액세스, https://journals.physiology.org/doi/pdf/10.1152/physiol.00002.2015
77. Information for Victims of Strangulation - Sheffield Health and Social Care, 7월 26, 2025에 액세스, https://www.shsc.nhs.uk/sites/default/files/2023-07/IFAS-01-Patient-Information.pdf
78. Strangulation: What Paramedics need to Know | County of San Diego, 7월 26, 2025에 액세스, https://www.sandiegocounty.gov/content/dam/sdc/ems/Medical_Director_Report/What%20Paramedics%20Need%20to%20Know.Strack.Worden.July%202021.pdf
79. Suicide methods - Wikipedia, 7월 26, 2025에 액세스, https://en.wikipedia.org/wiki/Suicide_methods
80. Drowning: Clinical Management - StatPearls - NCBI Bookshelf, 7월 26, 2025에 액세스, https://www.ncbi.nlm.nih.gov/books/NBK430833/
81. What Really Happens When Someone Drowns? - Aquatics International -, 7월 26, 2025에 액세스, https://www.aquaticsintl.com/lifeguards/what-really-happens-when-someone-drowns_o
82. Burns: Classification, Pathophysiology, and Treatment: A Review - PMC, 7월 26, 2025에 액세스, https://pmc.ncbi.nlm.nih.gov/articles/PMC9959609/
83. pathophysiology of burns :: www.forensicmed.co.uk, 7월 26, 2025에 액세스, https://www.forensicmed.co.uk/wounds/burns/pathophysiology-of-burns/
84. Burns: Symptoms, Degrees, How To Treat & Healing, 7월 26, 2025에 액세스, https://my.clevelandclinic.org/health/diseases/12063-burns
85. (PDF) The Pain of Burns: Characteristics and Correlates, 7월 26, 2025에 액세스, https://www.researchgate.net/publication/232197567_The_Pain_of_Burns_Characteristics_and_Correlates
86. Painad Scale – Arbor Hospice, 7월 26, 2025에 액세스, https://arborhospice.org/for-healthcare-professionals/painad-scale/