01Approach to the Critical Patient/attcp85

Recognition and immediate priorities

›Heat stroke stabilization

›Core temperature threshold

›Core temperature >= 40.0 C with CNS dysfunction

›Heat stroke possible with lower temperature after partial cooling

›Life threats

›Airway compromise

›Seizure

›Shock

›Severe electrolyte derangement

›Dysrhythmia

›Key immediate actions

›Move to cool environment

›Remove clothing and PPE

›Continuous core temperature monitoring

›Immediate active cooling as first priority

Cooling strategy and targets

›Rapid cooling goals

›Core temperature monitoring

›Rectal probe preferred for accuracy

›Esophageal probe acceptable if intubated

›Bladder probe unreliable during oliguria or irrigation

›Cooling target temperature

›Stop active cooling at 38.5 C to 39.0 C to avoid overshoot hypothermia

›Reassess every 5 minutes during active cooling

›Cooling method selection

›Exertional heat stroke

›Ice water immersion preferred when feasible

›Limb and trunk agitation in tub for convective flow

›Classic heat stroke

›Evaporative cooling with mist plus fan

›Ice packs to groin, axillae, neck as adjunct

›If immersion not feasible

›Cold water dousing plus fan

›Cooling blanket as adjunct only

›Cold IV fluids as adjunct

Airway, breathing, circulation

›Resuscitation bundle

›Airway and ventilation

›Indications for intubation

›Persistent agitation preventing cooling

›Inability to protect airway

›Refractory seizure

›Severe hypoxemia or respiratory failure

›Ventilation targets

›Normocapnia

›Avoid permissive hyperthermia from prolonged apneic periods

›Circulation

›IV access

›Two large bore peripheral IVs

›Consider intraosseous if access delayed

›Fluid strategy

›Isotonic crystalloid bolus for hypotension

›Reassessment with lung exam and ultrasound

›Avoid fluid overload in renal failure

›Vasopressors

›If hypotension persists after fluids

›Norepinephrine first line for distributive physiology

›Monitoring

›Continuous ECG

›Frequent blood pressure

›Pulse oximetry

›Capnography if intubated

›Foley for urine output if not contraindicated

Escalation and consultation triggers

›Early escalation

›ICU activation triggers

›Persistent altered mental status

›Temperature not decreasing with cooling

›Hypotension requiring vasopressors

›Seizure

›Lactate rising or metabolic acidosis

›Rhabdomyolysis with rising creatine kinase

›Acute kidney injury or oliguria

›Coagulopathy or bleeding

›Hepatic injury with rising aminotransferases

›Consultation triggers

›Nephrology for severe rhabdomyolysis or hyperkalemia

›Toxicology for unclear hyperthermia differential

›Hematology for DIC

›Obstetrics for pregnancy

›Pediatrics for children

PEARLS

›Heat stroke time critical principles

›Cooling is the definitive therapy

›Outcomes correlate with time above critical temperature

›Delays to cooling increase organ failure risk

›Skin findings unreliable

›Diaphoresis can be present in exertional heat stroke

›Hot dry skin does not exclude other hyperthermia causes

02History/hx49

Exposure and timeline

›Heat illness history framework

›Environment and exertion

›Ambient temperature and humidity

›Radiant heat exposure

›Duration of exposure

›Physical exertion intensity and duration

›Symptom timeline

›Time of collapse

›Preceding dizziness

›Syncope

›Confusion or behavior change

›Seizure activity

›Hydration and fueling

›Fluid intake

›Electrolyte replacement

›Weight change during activity

Risk factors and comorbidities

›Predisposing factors

›Impaired heat dissipation

›Lack of acclimatization

›Dehydration

›Heavy clothing or protective gear

›Limited access to shade or cooling

›Medical risk factors

›Cardiovascular disease

›Diabetes mellitus

›Chronic kidney disease

03Physical Exam/exam53

Vitals and general appearance

›Heat stroke exam priorities

›Temperature method

›Rectal temperature preferred

›Tympanic and oral temperature underestimation risk

›Hemodynamics

›Tachycardia

›Hypotension

›Wide pulse pressure

›Respiratory status

›Tachypnea

›Hypoxemia

›Pulmonary edema signs after fluids

Neurologic and mental status

›CNS dysfunction profile

›Level of consciousness

›Agitation

›Confusion

›Delirium

›Coma

›Seizure activity

›Overt convulsions

›Nonconvulsive seizure suspicion

›Focal findings

›Alternate diagnosis consideration if present

Skin and volume status

›Thermoregulation findings

›Skin temperature

04Differential Diagnosis/ddx38

Life threatening hyperthermia syndromes

›Critical differentials

›Heat stroke

›ICD-10 T67.0

›SNOMED CT heat stroke concept

›Sepsis with hyperthermia

›ICD-10 A41.9

›Serotonin syndrome

›ICD-10 T43.225A

›Neuroleptic malignant syndrome

›ICD-10 G21.0

›Malignant hyperthermia

›ICD-10 T88.3

›Sympathomimetic toxidrome

›ICD-10 T43.621A and related

›Thyroid storm

›ICD-10 E05.91

Neurologic and metabolic mimics

›Alternate causes of altered mental status

›Hypoglycemia

›ICD-10 E16.2

›Hyponatremia with encephalopathy

›ICD-10 E87.1

›Intracranial hemorrhage

›ICD-10 I61.9

›Acute ischemic stroke

›ICD-10 I63.9

›Meningitis or encephalitis

05Laboratory Tests/lt55

Initial critical labs

›Core heat stroke labs

›Metabolic and electrolytes

›Sodium for dysnatremia

›Hyponatremia risk with excessive hypotonic intake

›Hypernatremia risk with dehydration

›Potassium for arrhythmia risk

›Hyperkalemia risk with rhabdomyolysis

›Hypokalemia possible with sweating and diuretics

›Bicarbonate for metabolic acidosis

›High anion gap from lactate

›Creatinine for acute kidney injury

›Rising creatinine suggests pigment nephropathy

›Glucose for hypoglycemia and stress hyperglycemia

›Muscle and hemolysis

›Creatine kinase for rhabdomyolysis severity

›Rising trend predicts renal risk

›Urinalysis for heme with few RBCs

›Myoglobinuria surrogate

›Hepatic injury

›AST and ALT

›Very high values possible in severe heat stroke

›Bilirubin

›Coagulation and hematology

›Platelets for consumption and DIC

›PT and INR for coagulopathy

›aPTT for coagulopathy

›Fibrinogen for DIC

06Diagnostic Tests/dt47

Scoring Systems

›Risk stratification and organ dysfunction scores

›SOFA score for multi organ dysfunction

›Respiratory component

›PaO2 to FiO2 ratio in mmHg

›Coagulation component

›Platelet count

›Liver component

›Bilirubin

›Cardiovascular component

›MAP and vasopressor requirement

›CNS component

›GCS

›Renal component

›Creatinine and urine output

›JAAM heat illness severity classification

›Consciousness impairment

›Core temperature elevation

›Organ dysfunction markers

MRI

›MRI considerations

›Indications

›Persistent focal neurologic deficits after normothermia

›Suspected alternate CNS pathology

›Limitations

›Time and transport delays

›Not a priority over cooling

07Disposition/dispo30

Level of care decisions

›Disposition framework

›ICU admission criteria

›Heat stroke diagnosis with CNS dysfunction

›Ongoing altered mental status after normothermia

›Hypotension requiring vasopressors

›Mechanical ventilation requirement

›Seizure

›Creatine kinase markedly elevated or rising

›Acute kidney injury or oliguria

›Coagulopathy or DIC markers

›Hepatic injury with rising aminotransferases

›Severe metabolic acidosis

›Step down or monitored bed criteria

›Rapid neurologic recovery after cooling

›Stable hemodynamics without vasopressors

›Mild lab abnormalities with reliable trending plan

›Transfer criteria

›Need for ICU without local capacity

›Need for renal replacement therapy

›Need for advanced critical care resources

Observation and follow up planning

›Monitoring requirements

›Serial core temperature checks after cooling

›Rebound hyperthermia monitoring for 2 to 4 hours

›Serial labs

›Electrolytes every 4 to 6 hours initially

›Creatine kinase trend every 6 to 12 hours

08Treatment/t122

Cooling modalities

›Active cooling therapies

›Ice water immersion

›Indications

›Exertional heat stroke with safe airway control

›Practical considerations

›Continuous core temperature probe

›Airway monitoring with staff at head of tub

›Stop at 38.5 C to 39.0 C

›Evidence level

›Rapid cooling associated with improved outcomes

›Expert consensus strong recommendation Class I

›Evaporative cooling

›Indications

›Classic heat stroke

›When immersion not feasible

›Method

›Warm mist or tepid water spray

›High flow fan for convection

›Ice packs to groin and axilla as adjunct

›Evidence level

›Expert consensus recommendation Class I

›Adjunct cooling

›Cold IV isotonic crystalloid

›4 C saline as adjunct if available

›Gastric or bladder lavage

›Limited evidence

›Consider only in refractory hyperthermia with critical care support

Sedation, shivering, and agitation control

›Pharmacologic control of agitation and shivering

›Benzodiazepines

›Lorazepam IV 1 mg to 2 mg

›Repeat every 5 to 10 minutes as needed

›Max dose individualized by respiratory status

›Diazepam IV 5 mg to 10 mg

›Repeat every 5 to 10 minutes as needed

›Midazolam IV 2 mg to 5 mg

›Repeat every 5 minutes as needed

›Evidence level

›Shivering reduction to facilitate cooling

›Expert consensus ACEP Level C

›If intubated sedation strategies

›Propofol infusion

›Initiate 5 mcg/kg/min

›Titrate 5 mcg/kg/min to 10 mcg/kg/min every 5 minutes

›Typical range 5 mcg/kg/min to 50 mcg/kg/min

›Hypotension monitoring

›Dexmedetomidine infusion

›Initiate 0.2 mcg/kg/hour

›Titrate 0.1 mcg/kg/hour every 15 to 30 minutes

›Max 1.5 mcg/kg/hour

›Bradycardia monitoring

Airway and ventilation management

›Respiratory support

›Oxygen therapy

›Nasal cannula or mask to maintain saturation targets

›Intubation considerations

›Rapid sequence induction with hemodynamic awareness

›Avoid succinylcholine if severe hyperkalemia from rhabdomyolysis suspected

›Post intubation temperature monitoring with esophageal probe

Hemodynamics and fluids

›Circulatory support

›Isotonic crystalloid bolus

›500 mL to 1000 mL initial bolus adult

›Repeat based on perfusion and ultrasound

›Vasopressor strategy

›Norepinephrine infusion

›Initiate 0.05 mcg/kg/min

›Titrate every 2 to 5 minutes to MAP target

›Typical range 0.05 mcg/kg/min to 0.5 mcg/kg/min

›MAP target

›>= 65 mmHg in shock

›Higher targets individualized in chronic hypertension

Seizure management

›Seizure control

›Benzodiazepines first line

›Lorazepam IV 0.1 mg/kg

›Max single dose 4 mg

›Repeat once if needed

›Second line antiseizure therapy

›Levetiracetam IV 60 mg/kg

›Max 4500 mg

›Infuse over 10 to 15 minutes

›Refractory seizure escalation

›Continuous infusion sedation in ICU

Rhabdomyolysis and renal protection

›Rhabdomyolysis management

›Fluid strategy

›Isotonic crystalloid to support renal perfusion

›Urine output target

›1 mL/kg/hour to 2 mL/kg/hour

›Electrolyte monitoring

›Potassium trending

›Calcium trending

›Phosphate trending

›Renal replacement therapy triggers

›Refractory hyperkalemia

›Severe acidosis

›Volume overload with respiratory compromise

›Uremic complications

Coagulopathy and DIC

›Hemostatic management

›DIC supportive care

›Platelet transfusion if bleeding with thrombocytopenia

›Cryoprecipitate for low fibrinogen with bleeding

›Plasma for active bleeding with prolonged INR

›Evidence level

›Standard critical care consensus

›Expert consensus ACEP Level C

Temperature adjuncts and contraindicated therapies

›Adjunct and avoidance list

›Antipyretics

›No role in heat stroke

›Hepatotoxicity risk with acetaminophen

›Bleeding and renal risk with NSAIDs

›Dantrolene

›Not recommended for heat stroke

›Reserved for malignant hyperthermia

›Antibiotics

›Only if infection suspected based on clinical context

Evidence levels and guideline signals

›Evidence summary

›Rapid active cooling

›Strong recommendation Class I

›Expert consensus ACEP Level C

›Ice water immersion for exertional heat stroke

›Preferred when feasible

›Guideline supported in wilderness and sports medicine consensus

›Evaporative cooling for classic heat stroke

›Effective alternative when immersion not feasible

›Expert consensus recommendation

09Special Populations/sp38

Pregnancy

›Pregnancy considerations

›Maternal fetal risks

›Fetal distress risk with sustained maternal hyperthermia

›Preterm labor risk

›Cooling priorities

›Rapid maternal cooling as primary fetal therapy

›Left uterine displacement after mid pregnancy to reduce aortocaval compression

›Medication considerations

›Benzodiazepines for seizure and agitation when needed

›Avoid hypotension from sedatives

›Consultation

›Obstetrics for fetal monitoring and disposition

Geriatric

›Geriatric considerations

›Higher risk profile

›Impaired thirst and thermoregulation

›Chronic disease burden

›Limited mobility and social isolation

›Medication contributions

›Anticholinergics and sedatives

›Diuretics

›Beta blockers

›Fluid strategy nuance

›Lower tolerance for large boluses

›Early ultrasound guided resuscitation

Pediatrics

›Pediatric considerations

10Background/b39

Epidemiology

›Heat stroke population patterns

›Heat stroke categories

›Exertional heat stroke in athletes, military, outdoor workers

›Classic heat stroke in elderly, chronically ill, socially isolated

›Seasonal clustering

›Heat waves and high humidity periods

›Mortality drivers

›Time to cooling

›Multi organ failure burden

Pathophysiology

›Heat stroke mechanisms

›Thermoregulatory failure

›Heat production exceeding heat loss

›Impaired sweating and skin blood flow response

›Cellular injury

›Protein denaturation and enzyme dysfunction

›Mitochondrial failure

›Systemic inflammatory response

›Cytokine mediated endothelial injury

›Increased gut permeability and endotoxemia model

›Coagulopathy cascade

›Endothelial activation

›Platelet consumption and DIC potential

›Organ injury patterns

›CNS edema and neurotoxicity

›Hepatic necrosis

›Rhabdomyolysis and pigment nephropathy

11Patient Discharge Instructions/pdi19

Copy discharge instructions

›Discharge guidance for non heat stroke heat illness

›Rest and cooling

›Cool indoor environment for 24 to 48 hours

›Avoid exercise and heat exposure for 48 hours

›Hydration

›Oral fluids with electrolytes

›Avoid alcohol for 48 hours

›Medication guidance

›Avoid NSAIDs if kidney injury concern

›Follow up

›Primary care follow up within 24 to 72 hours

›Repeat labs if prior abnormalities

›Return to ED immediately

›Confusion, fainting, seizure, or severe headache

›Persistent vomiting or inability to keep fluids down

›Dark urine or no urination for 8 hours

›Chest pain, shortness of breath, or palpitations

›Recurrent fever or overheating symptoms

›Worsening weakness or muscle pain

12References/r18

Clinical guidelines and consensus statements

›Guideline sources

›Wilderness Medical Society practice guidelines for prevention and treatment of heat illness

›Ice water immersion recommended for exertional heat stroke when feasible

›Evaporative and convective methods as alternatives when immersion not feasible

›Sports medicine consensus statements on exertional heat stroke management

›Immediate cooling prior to transport when possible

›Critical care and emergency medicine references on hyperthermia syndromes

›Differentiation from serotonin syndrome and neuroleptic malignant syndrome

Evidence based sources

›Evidence anchors

›Observational evidence linking faster cooling to improved neurologic outcomes

›Time to target temperature as prognostic factor

›Comparative effectiveness data for cooling methods

›Immersion fastest cooling rates in exertional settings

›Evaporative cooling effective in classic presentations

›Expert consensus on supportive care complications

›Rhabdomyolysis management

›DIC management

›Renal replacement therapy triggers

Evidence & Review

Evidence & Review