II. Pathophysiology: Shock

  1. Circulatory insufficiency resulting in inadequate oxygen supply for given demand
  2. Triggers a cascading metabolic spiral culminating in cell injury and cell death
    1. Intracellular calcium overload
      1. Free radical oxidative damage
      2. Impaired mitochondrial ATP synthesis
      3. Impaired muscle relaxation and myocardial contractility
    2. Metabolic Acidosis
      1. Results from anaerobic metabolism, Lactic Acidosis, and Renal Failure
      2. Increases calcium overload
      3. Decreases myocardial and other muscle contractility
      4. Decreased Catecholamine response
      5. Increased interstitial edema
    3. Pro-inflammatory Cytokines (e.g. interleukins, tumor necrosis factor)
      1. Limited to specific shock types (e.g. Septic Shock, Anaphylaxis)
      2. Systemic vasodilation secondary to endothelial cell activation and nitric oxide release
  3. Compensatory Mechanisms
    1. Cardiac Output increase
      1. Responds to Catecholamine and cortisol release
    2. Arterial Vasoconstriction
      1. Selective shunting of blood flow from the skin, skeletal muscle, Kidney and gastrointestinal tract
    3. Venous constriction
      1. Increases Preload and return of blood to heart and brain
    4. Increased Sodium and water reabsorption
      1. Antidiuretic hormone
      2. Renin-Angiotensin System
  4. Failed compensation
    1. Metabolic Acidosis
    2. Coagulopathy (including Disseminated Intravascular Coagulation)
    3. Inflammatory mediator release
    4. Multiorgan dysfunction and death

III. Types

  1. Precautions: Undifferentiated Shock
    1. Many shock presentations are combinations of more than one shock type
    2. Septic Shock is primarily distributive shock, but also associated with third spacing and hypovolemic shock
    3. A massive tension pneumo-Hemothorax may cause both obstructive shock and hypovolemic shock
  2. Hypovolemic Shock
    1. Defined as intravascular fluid volume that is insufficient for adequate end-organ perfusion
    2. Hemorrhagic Shock
      1. Examples: Ruptured Abdominal Aortic Aneurysm, Trauma
    3. Dehydration
      1. Examples: Acute Gastroenteritis with Vomiting, Diarrhea
    4. Diabetic Ketoacidosis
  3. Distributive Shock
    1. Defined as systemic vasodilation that renders an otherwise sufficient circulating volume to be inadequate
    2. Septic Shock
      1. Systemic inflammatory response with diffuse, peripheral vasodilation and decreased Cardiac Output
    3. Neurogenic Shock
      1. Loss of sympathetic nervous function
      2. Results in decreased vascular tone, Bradycardia
    4. Anaphylaxis
      1. Mast cell degranulation
      2. Cytokine-induced vasodilation
  4. Cardiogenic Shock
    1. Defined as decreased Cardiac Index <1.8, increased left heart filling pressures
    2. Congestive Heart Failure
    3. Cardiomyopathy (e.g. Viral Myocarditis, cardiotoxic agents)
    4. Trauma (e.g. cardiac Contusion)
    5. Supraventricular Tachycardia or other arrhythmias
    6. Structural heart defects (e.g. valvular rupture, left to right shunt)
  5. Obstructive Shock
    1. Defined as heart or Great Vessel obstruction to flow with decreased Preload or increased Afterload
    2. Tension Pneumothorax
    3. Pericardial Tamponade
    4. Massive Pulmonary Embolism (increased RV Afterload, RV bowing limits LV filling)

IV. Causes (Mnemonic: SHRIMP CAN)

  1. Septic Shock
  2. Hypovolemic shock (e.g. Hemorrhagic Shock, severe dehydration)
  3. Respiratory Compromise (e.g. Tension Pneumothorax, massive Pulmonary Embolism)
  4. Ingestion (toxin, Overdose)
  5. Metabolic (e.g. DKA, Adrenal Insufficiency, Hypothyroidism)
  6. Psychiatric (water Intoxication)
  7. Cardiogenic Shock (MI, CHF, Cardiac Tamponade)
  8. Anaphylactic shock
  9. Neurogenic Shock (e.g. Spinal Shock)
  10. (2016) CALS Manual

V. History

  1. Medications and toxins
    1. Antiarrhythmics
    2. Anticoagulants
    3. Antihypertensives
    4. Diuretics
    5. Drugs of Abuse
    6. Poisons (Pesticides, toxic Alcohols, Cyanide exposure)
  2. Hypovolemia sources
    1. Ectopic Pregnancy
    2. Gastrointestinal losses
      1. Severe Diarrhea
      2. Vomiting
      3. Decreased oral intake
    3. Gastrointestinal Bleeding
      1. Melana
      2. Hematochezia
      3. Hematemesis
  3. Distributive causes (especially Septic Shock)
    1. Fever, chills, sweats or myalgias
    2. Infectious sources
      1. Cough or other respiratory symptoms
      2. Headache, neck stiffness or acute neurologic changes
      3. Focal Abdominal Pain (e.g. Acute Cholecystitis, Appendicitis, Diverticulitis)
      4. Urinary symptoms (e.g. Dysuria, urgency, frequency, flank pain)
      5. New rashes (e.g. Cellulitis)
    3. Predisposing factors
      1. Indwelling Urinary Catheter
      2. Indwelling lines (e.g. PICC Line)
      3. Retained Foreign Body (e.g. retained tampon)
      4. Recent procedures or surgeries
      5. Immunocompromised state
  4. Cardiogenic causes
    1. Chest Pain
    2. Shortness of Breath on exertion (e.g. decreased walk distance)
    3. Orthopnea or paroxysmal nocturnal Dyspnea
    4. Volume overload (recent increased weight)
  5. Obstructive causes
    1. Venous Thromboembolism Risks
    2. Recent Trauma

VI. Symptoms

  1. Light headedness
  2. Weakness
  3. Palpitations
  4. Fatigue
  5. Syncope
  6. Decreased urine output

VII. Signs

  1. Altered Mental Status (lethargy, coma)
  2. Dry mucous membranes
  3. Decreased skin turgur
  4. Pallor
  5. Delayed Capillary Refill

VIII. Signs: General

  1. See Primary Survey
  2. See Secondary Survey
  3. General Findings
    1. Diaphoresis
    2. Pallor
    3. Fever
  4. Head and neck findings
    1. Conjunctival pallor (Anemia)
    2. Dry mucous membranes
    3. Distented jugular neck veins
  5. Respiratory findings
    1. Tachypnea
    2. Kussmaul Respirations
    3. Asymmetric lung sounds (e.g. Pneumothorax, Pneumonia)
  6. Cardiovascular findings
    1. New cardiac murmur
    2. Pulsus Paradoxus
    3. Peripheral Edema (unilateral or bilateral)
    4. Decreased Capillary Refill
    5. Peripheral pulses (symmetry)
  7. Abdominal findings
    1. Peritoneal signs
    2. Pregnancy
    3. Ascites
    4. Ecchymosis
      1. Seat Belt Sign
      2. Flank or periumbilical Ecchymosis (intra-abdominal Hemorrhage)
  8. Neurologic findings
    1. See Glasgow Coma Scale
    2. Altered Mental Status
    3. From Disorientation to coma
    4. Extremity weakness

IX. Signs: Vital Signs

  1. See Toxin Induced Vital Sign Changes
  2. Heart Rate
    1. Compensatory Sinus Tachycardia
      1. Expected response to shock but inconsistently present
    2. Paradoxical absolute or relative Bradycardia
      1. May be seen in severe shock with decreased Cardiac Output
    3. Arrhythmias
      1. Primary Tachycardia or profound Bradycardia with secondary Cardiogenic Shock
  3. Blood Pressure
    1. Hypotension is a late response to shock
      1. In young children, Hypotension is even more ominous, with little warning to cardiovascular collapse
      2. Not uniformly present (do not rely on Blood Pressure alone to diagnose shock)
  4. Pulse Oximetry (Oxygen Saturation)
    1. Hypoxemia
    2. Hypoventilation
  5. Temperature
    1. Hypothermia or Hyperthermia
    2. Abnormal Temperature (high or low) may suggest SIRS Response
    3. Heat Illness or Accidental Hypothermia may also cause Hypotension or shock state
  6. Fingerstick Glucose (bedside Glucose)
    1. Severe Hyperglycemia
      1. Diabetic Ketoacidosis
      2. Hyperosmolar Hyperglycemic State
    2. Hypoglycemia
      1. May suggest overwhelming infection or Adrenal Insufficiency
  7. Other bedside evaluation of shock
    1. Passive Leg Raise Maneuver
    2. Shock Index
      1. Shock Index = (Heart Rate) / (Systolic Blood Pressure)
      2. Shock Index >0.9 is suggestive of significant shock necessitating immediate intervention

X. Labs (as indicated)

  1. Bedside
    1. Fingerstick Glucose (bedside Glucose)
  2. Miscellaneous initial labs
    1. Complete Blood Count
    2. Comprehensive metabolic panel
    3. Coagulation tests (INR, PTT)
    4. Venous Blood Gas
    5. Blood type and cross match
  3. Urine tests
    1. Urinalysis and Urine Culture
    2. Urine Pregnancy Test
    3. Urine toxicology
  4. Cardiac Markers
    1. Serum Troponin
    2. Brain Natriuretic Peptide (BNP)
  5. Infection suspected
    1. Serum Lactic Acid
    2. Blood Cultures
  6. Endocrine labs
    1. Thyroid Stimulating Hormone (TSH)
    2. Serum Cortisol

XI. Diagnostics

  1. Electrocardiogram
    1. See EKG in Myocardial Ischemia
    2. See EKG in Pulmonary Embolism
    3. See EKG monitoring in Trauma
    4. See QRS Widening
    5. See Prolonged QT
  2. Noninvasive monitoring (optional, but no proven protocols as of 2015)
    1. End-Tidal CO2 Monitoring
    2. Infrared spectroscopy
  3. Invasive monitoring (central catheter)
    1. Central oxygen
      1. Has been part of surviving Sepsis guidelines
        1. However as of 2015, Lactic Acid may be equivalent and without invasive monitoring
      2. Mixed venous Oxygen Saturation (Svo2) goal >65%
      3. Central venous Oxygen Saturation (Scvo2) goal >70%
    2. Central Venous Pressure
      1. Falling out of favor as of 2012
      2. Serial Inferior Vena Cava Ultrasound for Volume Status may be as effective without invasive testing

XII. Imaging

XIII. Management: Approach

  1. See ABC Management
  2. Treatment per specific causes as above
    1. See Trauma Evaluation
    2. See Hemorrhagic Shock
    3. See Septic Shock
    4. See Cardiogenic Shock
  3. Two large bore IVs (18 gauge or larger)
    1. Intraosseous Access if IV Access is unavailable
  4. Fluid Replacement
    1. Crystalloid (LR or NS)
    2. Packed Red Blood Cell transfusion as indicated (replace blood loss with blood)
  5. Fluid Responsiveness Markers
    1. See targets of adequate perfusion as listed below
    2. Assess Stroke Volume, cardiac ouput or surrogates before and after fluid challenge
      1. Administer 250-500 cc IV crystalloid challenge (over 10 minutes)
      2. Expect increased Stroke Volume >10-15% after fluid challenge
      3. Consider Vasopressors if poor response after the first liter (2L in Septic Shock)
    3. IVC Ultrasound for Volume Status
      1. Serial measurements may serve as guide to adequate fluid Resuscitation
    4. Passive Leg Raise Maneuver
      1. Elevation of both legs above the heart
      2. Provides a transient autologous fluid bolus of 300-400 cc
  6. Vasopressors (refractory severe Hypotension)
    1. Norepinephrine
    2. Vasopressin
    3. Epinephrine
  7. Respiratory support as needed
    1. See Noninvasive Ventilation
    2. See Advanced Airway
    3. See Rapid Sequence Intubation
      1. Ketamine may be a preferred induction agent in Hypotension
    4. Time intubation based on expectation of improvement with initial Resuscitation
      1. May resuscitate first and reassess if expect initial improvement in first 15 minutes
      2. Intubate if response to Resuscitation is expected to be delayed
    5. Choose short-acting post-intubation sedatives and Analgesics
      1. Avoid Benzodiazepines
      2. Preferred sedative: Dexmetetomidine
      3. Preferred Analgesic: Fentanyl
  8. Empiric Therapy
    1. See Septic Shock
      1. Empiric antibiotic selection based on suspected source
    2. Treat Hemorrhagic Shock
      1. Blood Products and emergent surgical intervention
    3. Consider empiric Adrenal Insufficiency management
      1. Hydrocortisone or Dexamethasone
    4. Consider cardiopulmonary causes with emergent interventions as indicated
      1. Acute Coronary Syndrome
      2. Massive Pulmonary Embolism
      3. Aortic Dissection (or other vascular catastrophe)
      4. Cardiac Tamponade
      5. Cardiogenic Shock

XIV. Management: Targets of adequate perfusion

  1. Exam markers
    1. Improved mentation
    2. Improved Capillary Refill (and decreased skin mottling)
    3. No findings of Fluid Overload (increased JVD, lung rales, Hypoxia)
  2. Lab, diagnostics and Vital Sign markers
    1. Mean arterial pressure (MAP): >65 mmHg (>50 mmHg may be preferred in Trauma)
    2. Urine output: >0.5 ml/kg/h
      1. Unreliable in Acute Kidney Injury
      2. Delayed response from time of fluid delivery to urine output response (risk of Fluid Overload)
    3. Serum Lactate Clearance (10% serum lactate reduction over 2 hours)
      1. Correlates with Central Venous Oxygen Saturation (ScvO2)
    4. IVC Ultrasound for Volume Status
      1. IVC collapses >50% on inspiration and is 1.5 to 2.5 cm in diameter
  3. Invasive markers
    1. Central Venous Pressure (CVP): 8-12 mmHg
      1. Falling out of favor, although still a part of 2012 surviving Sepsis guideline
      2. High CVP target is associated with Fluid Overload risk
    2. Central Venous Oxygen Saturation (ScvO2)
      1. Falling out of favor, although still a part of 2012 surviving Sepsis guideline
      2. No survival benefit in ProCESS, ARISE and ProMISE trials as target in Sepsis

XV. Precautions: Positive Fluid Balance

  1. Avoid over-compensating in Fluid Replacement (Positive Fluid Balance, hypervolemia, Fluid Overload)
  2. Adverse effects of Positive Fluid Balance
    1. Delirium
    2. Diastolic Dysfunction
    3. Cardiac conduction abnormalities
    4. Increased respiratory effort
    5. Decreased GFR
    6. Sodium retention
    7. Malabsorption
    8. Ileus
    9. Decreased Wound Healing
    10. Pressure Ulcers
  3. References
    1. Avila (2014) J Brasil Nefrol 36(3): 379-88 [PubMed]

XVI. References

  1. DeBlieux in Herbert (2016) EM:Rap 16(5):8-9
  2. Loflin (2015) Crit Dec Emerg Med 29(9): 11-18
  3. Goldberg (2015) Crit Dec Emerg Med 29(3): 9-19

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Ontology: Shock (C0036974)

Definition (MSH) A pathological condition manifested by failure to perfuse or oxygenate vital organs.
Definition (MEDLINEPLUS)

Shock happens when your blood pressure is too low and not enough blood and oxygen can get to your organs and tissues. Causes of shock include internal or external bleeding, dehydration, burns, or severe vomiting and/or diarrhea. All of these involve the loss of large amounts of body fluids. Shock often accompanies injury.

Specific types of shock include

  • Hypovolemic shock, caused by internal or external bleeding
  • Septic shock, caused by infections in the bloodstream
  • Anaphylactic shock, caused by a severe allergic reaction
  • Cardiogenic shock, caused by the inability of the heart to pump blood effectively
  • Neurogenic shock, caused by damage to the nervous system

Symptoms of shock include cold and sweaty skin, weak but rapid pulse, irregular breathing, dry mouth, dilated pupils and reduced urine flow. Shock is life threatening and it is important to get help right away. Treatment of shock depends on the cause.

National Institute of General Medical Sciences

Definition (NCI) A life-threatening condition that requires immediate medical intervention. It is characterized by reduced blood flow that may result in damage of multiple organs. Types of shock include cardiogenic, hemorrhagic, septic, anaphylactic, and traumatic shock.
Definition (CSP) a profound hemodynamic and metabolic disturbance characterized by the failure of the circulatory system to maintain adequate perfusion of vital organs; causes inadequate delivery of nutrients and insufficient removal of cellular waste products to and from the tissues.
Concepts Pathologic Function (T046)
MSH D012769
ICD9 785.50
ICD10 R57.9
SnomedCT 207026006, 267302008, 274729009, 158354004, 27942005
LNC LA7473-7
English Shock, CARDIOVASCULAR COLLAPSE, CIRCULATORY FAILURE, COLLAPSE CIRCULATORY, SHOCK CIRCULATORY, Shock, unspecified, Circulatory Collapse, Collapse, Circulatory, Failure/peripheral circul., Periph.circulatory failure, [D]Failure of peripheral circulation (context-dependent category), [D]Failure of peripheral circulation, [D]Failure/peripheral circul., [D]Periph.circulatory failure, [D]Peripheral circulatory failure, circulatory shock, shock, shock (diagnosis), Cardiovascular collapse, Collapse cardiovascular, Collapse circulatory, Collapse circulatory peripheral, Collapse peripheral circulatory, Failure peripheral circulatory, Shock circulatory, Collapse peripheral vascular, Collapse vascular, Vascular collapse, Shock vascular, Shock NOS, Failure circulatory, Failure of peripheral circulation NOS, Shock [Disease/Finding], Failure, Circulatory, Circulatory Failure, shock disorder, shocks, vascular collapse, shock syndrome, circulatory collapse, disorders shock, physiological shock, shocked, vascular shock, acute circulatory failure, circulatory failure, shocking, collapse, shock, physiological, cardiovascular collapse, Shock, unspecified (disorder), [D]Failure of peripheral circulation (situation), Circulatory shock, Circulatory failure, SHOCK, Circulatory collapse, Shock - physiological, Acute circulatory failure, Peripheral circulatory failure, Peripheral vascular failure, Peripheral vascular shutdown, Shock (disorder), cardiovascular; collapse, circulatory; collapse, collapse; cardiovascular, collapse; circulatory, collapse; vascular, shock; syndrome, syndrome; shock, vascular; collapse, Shock, NOS, Failure of peripheral circulation
French CHOC, Collapsus de la circulation périphérique, Défaillance de la circulation périphérique, Choc circulatoire, Choc, non précisé, Collapsus vasculaire périphérique, Choc d'origine vasculaire, CHOC CIRCULATOIRE, COLLAPSUS CARDIO-VASCULAIRE, COLLAPSUS CIRCULATOIRE, DEFAILLANCE CIRCULATOIRE, Défaillance circulatoire, Insuffisance circulatoire aiguë, Collapsus circulatoire, Défaillance circulatoire périphérique, Choc, État de choc, Collapsus cardio-vasculaire, Collapsus cardiovasculaire, Collapsus vasculaire, Collapsus
Portuguese CHOQUE, Choque circulatório, Colapso cardiovascular, Colapso circulatório, Colapso circulatório periférico, Colapso vascular periférico, Choque vascular, Choque NE, CHOQUE CIRCULATORIO, COLAPSO CARDIOVASCULAR, COLAPSO CIRCULATORIO, INSUFICIENCIA CIRCULATORIA, Insuficiência circulatória, Insuficiência circulatória aguda, Insuficiência Circulatória, Choque Circulatorio, Colapso da Circulação Periférica, Choque Hemodinâmico, Colapso vascular, Insuficiência circulatória periférica, Choque, Colapso Circulatório
German SCHOCK, kardiovaskulaerer Kollaps, Schock Kreislauf, Schock vaskulaer, Schock, unspezifisch, Kollaps, Kreislauf, Versagen des peripheren Kreislaufs, Kollaps, kardiovaskulaer, Versagen der peripheren Gefaesse, vaskulaerer Kollaps, Kollaps vaskulaer, KOLLAPS KARDIOVASKULAER, KREISLAUFKOLLAPS, KREISLAUFSCHOCK, KREISLAUFVERSAGEN, Schock, nicht naeher bezeichnet, Kreislaufversagen, akutes Kreislaufversagen, Versagen des Kreislaufs, peripheres Kreislaufversagen, Kreislaufkollaps, Schock
Spanish SHOCK, Colapso circulatorio periférico, Colapso vascular, Shock no especificado, Colapso cardiovascular, Shock vascular, Colapso vascular periférico, Insuficiencia de la circulación periférica, Shock circulatorio, [D]insuficiencia circulatoria periférica (categoría dependiente del contexto), COLAPSO CARDIOVASCULAR, COLAPSO CIRCULATORIO, INSUFICIENCIA CIRCULATORIA, SHOCK CIRCULATORIO, Fallo circulatorio, Fallo circulatorio agudo, Insuficiencia Circulatoria, Choque, shock, no especificado, choque, no especificado, [D]insuficiencia circulatoria periférica, choque, no especificado (trastorno), [D]insuficiencia circulatoria periférica (situación), Choque Circulatorio, Choque Hemodinámico, Shock, Shock Hemodinámico, Shock Hipovolémico, choque (trastorno), choque, insuficiencia circulatoria aguda, insuficiencia circulatoria periférica, insuficiencia vascular aguda, insuficiencia vascular periférica, shock, Colapso circulatorio, Insuficiencia circulatoria periférica, Colapso Circulatorio
Italian Insufficienza circolatoria periferica, Shock non specificato, Collasso vascolare periferico, Collasso vascolare, Collasso cardiovascolare, Collasso circolatorio periferico, Shock vascolare, Shock circolatorio, Collasso circolatorio, Insufficienza circolatoria acuta, Insufficienza circolatoria, Shock
Dutch collaps perifere circulatie, perifere circulatoire collaps, vasculaire collaps, collaps cardiovasculair, perifere vaatcollaps, cardiovasculaire collaps, vasculaire shock, collaps circulatoir, falen perifere circulatie, circulatoire shock, niet-gespecificeerde shock, collaps vasculair, circulatoir falen, acuut circulatoir falen, falen circulatoir, cardiovasculair; collaps, circulatoir; collaps, collaps; cardiovasculair, collaps; circulatoir, collaps; vasculair, shock; syndroom, syndroom; shock, vasculair; collaps, Shock, niet gespecificeerd, circulatoire collaps, perifeer circulatoir falen, shock, Cardiovasculaire shock, Circulatiestoring, Shock
Japanese 循環性ショック, 血管性ショック, 循環虚脱, 心血管虚脱, 末梢性循環虚脱, 末梢循環性虚脱, 血管虚脱, ショック、詳細不明, 末梢循環不全, 末梢血管虚脱, マッショウケッカンキョダツ, ケッカンセイショック, ケッカンキョダツ, マッショウジュンカンセイキョダツ, マッショウジュンカンフゼン, ジュンカンセイショック, マッショウセイジュンカンキョダツ, ショック, シンケッカンキョダツ, ショックショウサイフメイ, ジュンカンキョダツ, ショック症状, 急性循環不全, 循環不全, キュウセイジュンカンフゼン, ジュンカンフゼン, ショック, 急性循環不全状態
Swedish Chock
Czech šok, Kolaps oběhový, Periferní oběhový kolaps, Šok cévní, Periferní cévní kolaps, Selhání periferní cirkulace, Cévní kolaps, Kolaps kardiovaskulární, Periferní oběhové selhání, Šok, Šok, blíže neurčený, Oběhový šok, Kardiovaskulární kolaps, Oběhový kolaps, Oběhové selhání, Akutní oběhové selhání, Selhání cirkulace
Finnish Sokki
Russian SHOK, GIPOVOLEMICHESKII SHOK, ГИПОВОЛЕМИЧЕСКИЙ ШОК, ШОК
Korean 상세불명의 쇼크
Croatian ŠOK
Polish Wstrząs, Wstrząs oligowolemiczny, Ostra niewydolność krążenia
Hungarian A keringés összeomlása, Peripheriás keringési összeomlás, Keringésösszeomlás, A peripheriás keringés összeomlása, Keringési shock, Peripheriás keringési elégtelenség, Shock, Elégtelenség, peripheriás keringés, Peripheriás vascularis collapsus, Szív-érrendszer eredetű collapsus, Keringési elégtelenség, Cardiovascularis collapsus, Vascularis collapsus, Vascularis shock, Shock, nem meghatározott, Heveny keringési elégtelenség
Norwegian Sjokk, Sirkulasjonssvikt, Sirkulasjonskollaps