High Acuity and Critical Care: Neuro, Burns, Trauma, SIRS, Sepsis, and Disaster Management

Comprehensive practice flashcards in vocabulary style covering high-acuity neurological concepts, burn pathophysiology and fluid management, trauma assessment, shock states, SIRS, sepsis bundles, and mass casualty disaster triage.

Monro-Kellie Hypothesis

The physiological principle stating that the rigid cranial vault contains a fixed total intracranial volume composed of brain tissue ($78\%$), intravascular blood ($12\%$), and cerebrospinal fluid ($10\%$); an increase in any one component requires a reciprocal decrease in another, or intracranial pressure will rise.

Normal Intracranial Pressure (ICP)

The pressure exerted inside the skull by brain tissue, blood, and CSF, normally ranging between $0\text{ and }15\,mmHg$ ($5\text{ to }15\,mmHg$); clinical intervention is generally indicated when sustained levels exceed $20\,mmHg$.

Cerebral Perfusion Pressure (CPP)

The pressure gradient that drives blood flow and oxygen delivery to cerebral tissue, calculated by the formula $\text{CPP} = \text{MAP} - \text{ICP}$; clinically maintained above $70\,mmHg$ in injured neurological patients ($60\,mmHg$ in non-injured baseline), where levels below $50\,mmHg$ cause ischemia and below $30\,mmHg$ cause irreversible damage.

Cushing's Reflex (Cushing's Triad)

A late, grave neurological response to severe intracranial hypertension and impending brain herniation, clinically characterized by progressive systolic hypertension with a widening pulse pressure, bradycardia, and irregular respiratory patterns.

Brain Herniation

The life-threatening, irreversible displacement of brain tissue across rigid anatomical structures (such as through the tentorial notch or foramen magnum) from a compartment of higher pressure to one of lower pressure due to uncompensated intracranial hypertension.

External Ventricular Drain (EVD) Zero Reference Point

The external anatomical landmark used to calibrate and zero the pressure transducer of an intraventricular catheter, specifically leveled with the foramen of Monro at the tragus or top of the patient's ear with the head of the bed maintained at $30^\circ$.

Decorticate Posturing

An abnormal flexion motor response indicating damage to voluntary motor pathways within the cerebral cortex, manifested by rigid adduction and flexion of the arms across the chest, clenched fists, and extended, internally rotated legs with plantar flexion (scored as $3$ on the Glasgow Coma Scale).

Decerebrate Posturing

An abnormal extension motor response indicating severe structural disruption of the midbrain or brainstem, manifested by rigid adduction, hyperpronation, and extension of the arms along with extended legs and plantar flexion (scored as $2$ on the Glasgow Coma Scale; worse prognosis than decorticate posturing).

Basilar Skull Fracture

A fracture at the base of the skull involving a dural tear, clinically recognized by periorbital ecchymosis ("raccoon eyes"), mastoid ecchymosis ("Battle's sign"), otorrhea or rhinorrhea showing a halo sign, and presenting a strict contraindication to nasogastric tube insertion.

Epidural Hematoma

A neurosurgical emergency involving arterial bleeding into the space between the dura mater and the inner surface of the skull, classically presenting with an initial loss of consciousness, a brief lucid interval, followed by rapid neurological decline, ipsilateral pupil dilation, and contralateral hemiparesis.

Subdural Hematoma

A vascular injury involving venous rupture of bridging veins between the dura and arachnoid membranes; categorized based on onset as acute ($24\text{ to }48\,\text{hours}$), subacute ($2\text{ to }14\,\text{days}$), or chronic (weeks to months), which is particularly prevalent in the elderly due to cerebral atrophy.

Triple H Therapy

The standard therapeutic regimen used to prevent and manage cerebral vasospasm following subarachnoid hemorrhage, consisting of Hypervolemia, induced Hypertension (often targeting systolic blood pressure between $140\text{ and }160\,mmHg$), and Hemodilution to decrease blood viscosity and drive cerebral perfusion.

Cerebral Vasospasm

A transient, reactive narrowing of cerebral blood vessels provoked by blood degradation products in the subarachnoid space, typically occurring $3\text{ to }15\,\text{days}$ post-hemorrhage (peak at $7\text{ to }10\,\text{days}$) and presenting with fluctuating, waxing-and-waning neurological deficits such as hemiparesis, dysphagia, and decreased level of consciousness.

Arteriovenous Malformation (AVM)

A congenital vascular anomaly characterized by an absent or deficient capillary bed, causing high-pressure arterial blood to shunt directly into thin-walled cerebral veins, predisposing the vessel cluster to turbulent flow, enlargement, rupture, and intracerebral hemorrhagic stroke.

Status Epilepticus

A neurological emergency characterized by continuous seizure activity or recurrent seizures in rapid succession without recovery of consciousness between episodes, treated initially with first-line intravenous benzodiazepines such as lorazepam ($2\,mg/min$).

Purple Glove Syndrome

A rare, limb-threatening complication associated with the peripheral intravenous administration of phenytoin ($\text{pH} \approx 12$), characterized by progressive edema, purplish discoloration, warmth, and severe pain in the distal extremity that can evolve into compartment syndrome.

Spinal Shock

A temporary neurogenic syndrome occurring immediately after acute traumatic spinal cord injury, characterized by the depression or total loss of all spinal reflex activity, sensation, and flaccid paralysis below the level of injury, lasting days to months until reflexes return.

Neurogenic Shock

A form of distributive shock resulting from the disruption of descending sympathetic outflow in spinal cord injuries at or above $T6$ (or high spinal anesthesia), characterized hemodynamically by the triad of hypotension, bradycardia, and peripheral vasodilation with poikilothermia.

Autonomic Dysreflexia

A life-threatening hypertensive emergency occurring after spinal shock has resolved in injuries at or above $T6$, triggered by uninhibited sympathetic response to a noxious visceral stimulus below the lesion (most commonly a distended bladder or impacted bowel), presenting with severe hypertension, pounding headache, bradycardia, diaphoresis above the lesion, and piloerection.

Guillain-Barré Syndrome

An acute, post-infectious, cell-mediated autoimmune polyneuropathy causing demyelination of peripheral nerves and cranial nerves ($3, 7, 9\text{--}12$), classically presenting with symmetrical ascending muscle weakness, paresthesias, and diminished reflexes, with the major clinical danger being diaphragmatic respiratory failure.

Marcus Gunn Pupil

An abnormal pupillary finding (relative afferent pupillary defect) often resulting from trauma to the optic nerve, in which the affected pupil paradoxically dilates instead of constricting when a light is swung from the unaffected eye directly onto the affected eye.

Cheyne-Stokes Respirations

An abnormal respiratory rhythm characterized by a gradual crescendo-decrescendo pattern of increasing rate and depth of breathing followed by a period of apnea, commonly observed in deep coma, metabolic encephalopathies, or terminal intracranial hypertension.

Brain Death Criteria

The formal clinical determination of irreversible cessation of all brain and brainstem function, defined by profound coma/unresponsiveness, absent brainstem reflexes (pupillary, corneal, cough, gag, oculocephalic, and oculovestibular), and a positive apnea test exhibiting no spontaneous respirations when $\text{PaCO}_2 \ge 60\,mmHg$.

Cerebral Salt Wasting Syndrome (CSW)

An intracranial pathology characterized by renal loss of both sodium and extracellular fluid volume, presenting clinically with hyponatremia and hypovolemia; treated with volume replacement using $0.9\%\,\text{NaCl}$ and hypertonic $3\%\,\text{NaCl}$ (infused at a controlled rate of $\le 30\,mL/hr$ to avoid central pontine myelinolysis).

Mannitol

An intravenous osmotic diuretic administered on a PRN basis to reduce acute cerebral edema by drawing free water from brain parenchyma into the vascular space for renal excretion; requires monitoring of serum osmolality and must be held if osmolality exceeds $320\,mOsm/kg$.

Nimodipine

A neuroprotective calcium channel blocker prescribed for $21\,\text{days}$ following aneurysmal subarachnoid hemorrhage to prevent and manage cerebral arterial vasospasm; held if systolic blood pressure is below $90\,mmHg$ or heart rate is below $60\,\text{bpm}$.

Second-Degree Burn (Partial Thickness)

A cutaneous burn involving the entire epidermis and varying depths of the dermis, manifesting as moist, shiny, fluid-filled blisters that weep serous fluid and demonstrate exquisite sensitivity to cold air and touch (or a dull, waxy red/white appearance if deep dermis is involved), healing within $14\text{ to }21\,\text{days}$.

Third-Degree Burn (Full Thickness)

A severe burn involving complete destruction of both the epidermis and dermis into the underlying subcutaneous adipose tissue, presenting with a dry, leathery, charred black, yellow, or waxy white appearance that is insensate to light touch/pinprick and requires surgical excision and autografting.

Rule of Nines

A clinical estimation tool used to calculate the percentage of total body surface area ($\%\,\text{TBSA}$) burned in an adult: head ($9\%$ total; $4.5\%$ anterior, $4.5\%$ posterior), anterior trunk ($18\%$), posterior trunk ($18\%$), each arm ($9\%$ total; $4.5\%$ anterior, $4.5\%$ posterior), each leg ($18\%$ total; $9\%$ anterior, $9\%$ posterior), and perineum ($1\%$).

Parkland Formula

The standard fluid resuscitation calculation for the first $24\,\text{hours}$ following thermal injury: $4\,mL \times \text{weight in }kg \times \%\,\text{TBSA burned}$ of Lactated Ringer's solution, with the first $50\%$ administered over the first $8\,\text{hours}$ from the time of injury and the remaining $50\%$ divided equally over the next $16\,\text{hours}$.

Burn Shock

A severe combined hypovolemic and distributive shock state occurring in burns greater than $20\%\,\text{TBSA}$, precipitated by widespread inflammatory mediator release that produces capillary leak syndrome, profound third spacing of intravascular plasma and proteins, hemoconcentration, and cellular edema.

Carbon Monoxide Poisoning

A toxic inhalation condition resulting from the combustion of organic materials, wherein carbon monoxide binds to hemoglobin with an affinity $200$ times greater than oxygen, causing tissue hypoxia and presenting with headache, confusion, syncope, and classically cherry-red skin discoloration.

Curling's Ulcer

An acute, stress-induced gastroduodenal ulcer that develops within $24\,\text{hours}$ after extensive burn trauma, caused by profound mucosal ischemia, sloughing, and decreased protective mucus secretion secondary to hypoperfusion; prevented with early enteral nutrition and prophylactic PPIs or H2 blockers.

Escharotomy

A surgical bedside or operative incision performed longitudinally through thick, unyielding, avascular burn eschar to relieve elevated interstitial compartment pressures in a circumferentially burned extremity or to restore adequate chest wall compliance on a restricted thorax.

Mafenide Acetate (Sulfamylon)

A topical broad-spectrum antimicrobial agent used on deep partial- and full-thickness burn wounds that successfully penetrates thick eschar, but causes intense local burning pain upon application and carries a risk of metabolic acidosis via carbonic anhydrase inhibition.

Silver Sulfadiazine (Silvadene)

A painless, water-soluble, broad-spectrum topical antibacterial cream applied to deep partial- and full-thickness burn wounds to prevent infection, requiring caution or avoidance in patients with documented sulfonamide (sulfa) allergies.

Trauma Triad of Death

A lethal self-propagating physiologic triad observed in severe hemorrhage, consisting of Hypothermia (core temperature $< 35\,^\circ\text{C}$, halting the coagulation cascade), Metabolic Acidosis (from cellular hypoperfusion and anaerobic metabolism), and Coagulopathy.

Primary Trauma Survey

The rapid, systematic initial assessment designed to identify and immediately manage life-threatening injuries in a trauma victim, sequenced as Airway and cervical spine stabilization ($A$), Breathing and ventilation ($B$), Circulation and hemorrhage control ($C$), Disability/neurological status ($D$), and Exposure/environmental control ($E$).

Secondary Trauma Survey

The detailed head-to-toe clinical assessment initiated only after life-threatening injuries in the primary survey are stabilized, sequenced as Full set of vital signs ($F$), Give comfort measures ($G$), Head-to-toe examination and history ($H$), and Inspect posterior surfaces ($I$).

Flail Chest

A severe chest wall injury occurring when two or more adjacent ribs are fractured in two or more places, creating a detached, free-floating thoracic segment that moves paradoxically (sucking inward during inspiration and ballooning outward during expiration).

Tension Pneumothorax

A life-threatening thoracic emergency in which air enters the pleural space on inspiration but cannot escape, causing progressive intrapleural air accumulation, mediastinal shift and tracheal deviation to the contralateral side, compression of the great veins leading to obstructive shock, and pulseless electrical activity (PEA).

Cullen's Sign

A superficial bluish-purple ecchymosis localized around the umbilicus, indicating extensive retroperitoneal or intraperitoneal hemorrhage commonly associated with severe hepatic or splenic rupture and acute pancreatitis.

Grey Turner's Sign

A bluish-purple discoloration or bruising located along the flanks, serving as a physical examination sign of severe retroperitoneal hemorrhage (often secondary to pancreatic, renal, or pelvic vascular trauma).

Kehr's Sign

Referred, acute pain radiating to the left shoulder tip caused by diaphragmatic peritoneal irritation from blood accumulation in the left upper quadrant, serving as a classic indicator of splenic laceration or rupture.

Diagnostic Peritoneal Lavage (DPL)

An invasive diagnostic procedure in blunt or penetrating abdominal trauma involving the insertion of a catheter into the peritoneal cavity to aspirate blood; an immediate return of frank blood indicates internal organ injury requiring emergent exploratory laparotomy.

Fat Embolism Syndrome (FES)

A systemic complication following fractures of long bones (such as the femur or tibia) or pelvis, wherein fat globules enter circulation from bone marrow disruption, classically presenting with dyspnea/hypoxemia, altered mental status, and a petechial rash across the chest, axilla, and conjunctiva.

Obstructive Shock

A form of circulatory shock characterized by a physical mechanical impediment that restricts diastolic cardiac filling or impedes outflow from the ventricles, drastically decreasing cardiac output; etiologies include tension pneumothorax, cardiac tamponade, massive pulmonary embolism, and severe abdominal compartment syndrome ($\text{bladder pressure} > 20\,mmHg$).

SIRS (Systemic Inflammatory Response Syndrome) Criteria

A systemic inflammatory response manifested by two or more of the following: core temperature $> 38\,^\circ\text{C}$ ($100.4\,^\circ\text{F}$) or $< 36\,^\circ\text{C}$ ($96.8\,^\circ\text{F}$); heart rate $> 90\,\text{bpm}$; respiratory rate $> 20\,\text{breaths/min}$ or $\text{PaCO}_2 < 32\,mmHg$; WBC count $> 12{,}000/\mu\text{L}$, $< 4{,}000/\mu\text{L}$, or $> 10\%$ immature band forms.

Sepsis

A life-threatening organ dysfunction caused by a dysregulated and overwhelming systemic host response (meeting SIRS criteria) to a confirmed or suspected infectious etiology.

Septic Shock

A severe subset of sepsis in which underlying circulatory, cellular, and metabolic derangements are profound enough to cause persistent hypotension requiring vasopressors to maintain a $\text{MAP} \ge 65\,mmHg$ and a serum lactate $> 2\,mmol/L$ despite adequate crystalloid volume resuscitation.

Surviving Sepsis Hour-1 Bundle

An evidence-based resuscitation bundle initiated within the first hour of sepsis identification: 1) measure serum lactate level (remeasure if $> 2\,mmol/L$); 2) obtain blood cultures prior to antibiotic therapy; 3) administer broad-spectrum intravenous antibiotics; 4) begin rapid administration of $30\,mL/kg$ crystalloid for hypotension or lactate $\ge 4\,mmol/L$; and 5) apply vasopressors (norepinephrine first-line) to maintain $\text{MAP} \ge 65\,mmHg$.

Disseminated Intravascular Coagulation (DIC)

A paradoxical bleeding and thrombotic disorder secondary to underlying disease (sepsis, trauma), wherein uncontrolled systemic activation of thrombin produces widespread microvascular clots, leading to consumption of clotting factors and platelets; laboratory profile shows elevated D-dimer ($> 250\,ng/mL$), prolonged PT/PTT, decreased fibrinogen ($< 100\,mg/dL$), and thrombocytopenia ($< 150{,}000/\mu\text{L}$).

Multiple Organ Dysfunction Syndrome (MODS)

The progressive failure and altered function of two or more organ systems in an acutely ill patient such that physiological homeostasis cannot be maintained without aggressive medical intervention; typically represents the end-stage progression of uncontrolled SIRS and refractory septic shock.

Disaster Triage Tag: Red (Immediate)

A mass casualty triage classification designating victims with life-threatening injuries who require immediate medical intervention within minutes to survive, but who have a high likelihood of survival if promptly treated (e.g., tension pneumothorax, treatable external hemorrhage, unstable airway).

Disaster Triage Tag: Yellow (Delayed)

A mass casualty triage classification designating victims with serious, systemic injuries whose care and definitive surgical management can be safely delayed for several hours without immediate threat to life or limb (e.g., closed fractures, open wounds without active hemorrhage).

Disaster Triage Tag: Green (Minor)

A mass casualty triage classification designating the "walking wounded" whose injuries are minor, localized, and can safely wait hours to days for treatment (e.g., simple sprains, minor burns, superficial lacerations).

Disaster Triage Tag: Black (Expectant / Deceased)

A mass casualty triage classification assigned to disaster victims who are deceased or whose catastrophic, severe injuries offer very low chance of survival given available resource constraints (e.g., massive penetrating head injury, unresponsiveness with fixed and dilated pupils, full-thickness burns $> 60\%\,\text{TBSA}$ in profound shock).