Perfusion: Shock

NSG 117
J. Powell, MSN, RN

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Definition
Perfusion refers to the flow of blood through
arteries and capillaries, delivering nutrients and
oxygen to cells.

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Other Key Terms
• Ischemia
• Infarction
• Anoxia

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Scope of Concept

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Review of Cardiovascular System
Anatomy and Physiology

• Heart
• Arteries
• Veins
• Capillaries

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Normal Physiological Process
Central Perfusion Tissue or Local Perfusion
• Force of blood • Volume of blood that
movement generated by flows to target tissue
cardiac output • Requires patent vessels,
• Requires adequate adequate hydrostatic
cardiac function, blood pressure, and capillary
pressure, and blood permeability
volume
• Cardiac output (CO) =
Stroke volume × heart
rate 6
Central Perfusion and Tissue
Perfusion

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Variations and Consequences:
Impaired Central Perfusion
• Impairment of central perfusion occurs when cardiac output is
inadequate.
• Reduced cardiac output results in a reduction of oxygenated
blood reaching the body tissues (systemic effect).
• If severe, associated with shock
• If untreated, leads to ischemia, cell injury, and cell death

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Variations and Consequences:
Impaired Tissue (Local) Perfusion

• Impairment of tissue perfusion is associated with loss of

vessel patency or permeability, or inadequate central
perfusion
• Results in impaired blood flow to the affected body tissue
(localized effect)
• Leads to ischemia and, ultimately, cell death if uncorrected

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Risk Factors:
Populations at Greatest Risk
Impaired perfusion can potentially occur among all individuals,
regardless of age, gender, race, or socioeconomic status. The
populations at greatest risk are:
• Middle-aged and older adults
• Men
• African Americans

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Common Diagnostic Tests
• Laboratory tests
• Creatine kinase, lactic dehydrogenase, natriuretic peptides,
troponin, homocysteine, C-reactive protein, serum lipids,
platelets, prothrombin time (PT), partial thromboplastin time
(PTT), international normalized ratio (INR)
• Electrocardiogram (ECG)
• Cardiac stress tests
• Exercise or pharmacological test
• Radiographic studies
• Chest x-ray, ultrasound, arteriogram

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Pharmacotherapy:
Impaired Central Perfusion
• Antihypertensives
• Antiarrhythmics
• Inotropics
• Antianginal agents
• Vasopressors
• Vasodilators

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Pharmacotherapy: Impaired Tissue
(Local) Perfusion
• Anticoagulants
• Thrombolytics
• Lipid-lowering agents
• Vasodilators
• Antiplatelet agents and platelet inhibitors

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Other Collaborative Interventions

Central Perfusion Tissue (Local) Perfusion

• Pacemaker insertion • Bypass and/or graft
• Electrical cardioversion surgery
• Ablation therapy • Stent or angioplasty
• Intraaortic balloon pump • Endarterectomy
• Cardiac valve surgery
• Cardiac transplant

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Interrelated Concepts
• Gas exchange
• Pain
• Clotting
• Cognition
• Mobility
• Elimination
• Inflammation
• Patient education
• Nutrition
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Shock
• Syndrome characterized by decreased tissue perfusion and
impaired cellular metabolism
• Imbalance in supply/demand for O2 and nutrients

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Shock
• Classification of shock
• Cardiogenic
• Hypovolemic
• Distributive
• Obstructive

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Low Blood Flow
Cardiogenic Shock
• Definition
• Systolic or diastolic dysfunction
• Compromised cardiac output (CO)
• Heart can not pump enough blood to meet the body’s
demands
• Rare condition caused by a severe heart attack

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Hypovolemic Shock
• Life-threatening condition that results when more than 20% of
the body’s blood or fluid supply is loss
• Severe enough fluid loss that results in the heart not pumping
a sufficient amount of blood to the body

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Distributive Shock
• Condition in which abnormal distribution of blood flow in the
smallest blood vessels results in inadequate supply of blood to
the body’s tissues and organs
• 1. Sepsis: Septic Shock
• 2. Neurogenic Shock: Low blood pressure with low heart rate
that is the result of disruption of the autonomic pathways of
the spinal cord.
• 3. Anaphylactic Shock: Hypersensitivity reaction to a
sensitizing substance (e.g., drug, chemical, vaccine, food,
insect venom) that results in massive vasodilation

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Obstructive Shock
• Physical obstruction of the great vessels or the heart
• Pulmonary embolism and cardiac tamponade
• Obstructive shock and cardiogenic show are grouped together

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Types of Shock

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Low Blood Flow
Hypovolemic Shock
• Absolute hypovolemia: loss of intravascular fluid volume
• Hemorrhage
• GI loss (e.g., vomiting, diarrhea)
• Fistula drainage
• Diabetes insipidus
• Hyperglycemia
• Diuresis

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Low Blood Flow
Hypovolemic Shock
• Relative hypovolemia
• Results when fluid volume moves out of the vascular space into
extravascular space (e.g., intracavitary space)
• Termed third spacing

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Pathophysiology of Hypovolemic Shock

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(Modified from Urden LD, Stacy KM, Lough ME: Critical care nursing: diagnosis and management, ed 6, St Louis, 2010,
Mosby)
Copyright © 2017, Elsevier Inc. All Rights Reserved.
Low Blood Flow
Hypovolemic Shock
• Response to acute volume loss depends on:
• Extent of injury
• Age
• General state of health

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Low Blood Flow
Hypovolemic Shock
• Clinical manifestations
• Anxiety
• Tachypnea
• Increase in CO, heart rate
• Decrease in stroke volume, PAWP, urinary output
• If loss is >30%, blood volume is replaced

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Stages of Shock
• Shock is categorized into 4 overlapping stages:
• Initial
• Compensatory
• Progressive
• Refractory

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Stages of Shock
Initial Stage
• Usually not clinically apparent
• Metabolism changes at cellular level from aerobic to
anaerobic
• Lactic acid builds up and must be removed by liver
• Process requires O2, unavailable due to decreased tissue
perfusion

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Stages of Shock
Compensatory Stage
• Compensatory mechanisms
• Neural
• Hormonal
• Biochemical
• Attempt to overcome consequences of anaerobic metabolism
and maintain homeostasis

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Stages of Shock
Compensatory Stage
• Baroreceptors in carotid and aortic bodies activate SNS in
response to ↓ BP
• Vasoconstriction while blood to vital organs maintained
• Heart
• Brain

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Stages of Shock
Compensatory Stage
• Body is able to compensate for changes in tissue perfusion
• If cause of shock is corrected, patient recovers with little or no
residual effects
• If cause of shock is not corrected, patient enters progressive
stage

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Stages of Shock
Progressive Stage
• Begins when compensatory mechanisms fail
• Patient moved to ICU for advanced monitoring and treatment

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Stages of Shock
Progressive Stage
• Distinguishing features of ↓ cellular perfusion and altered
capillary permeability
• Leakage of protein into interstitial space
• ↑ Systemic interstitial edema

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Stages of Shock
Progressive Stage
• Fluid moves into alveoli
• Edema
• Decreased surfactant
• Worsening V/Q mismatch
• Tachypnea
• Crackles
• Increased work of breathing

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Stages of Shock
Progressive Stage
• Mucosal barrier of GI system becomes ischemic
• Ulcers
• GI bleeding
• Risk of migration of bacteria
• Decreased ability to absorb nutrients

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Stages of Shock
Progressive Stage
• Hypoperfusion leads to renal tubular ischemia
• May result in acute kidney injury
• Worsened by nephrotoxic drugs
• Decreased urine output
• Elevated BUN and serum creatinine

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Stages of Shock
Progressive Stage
• Liver fails to metabolize drugs and waste
• Jaundice
• Elevated enzymes
• Loss of immune function
• Risk for significant bleeding

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Stages of Shock
Refractory Stage
• Exacerbation of anaerobic metabolism
• Accumulation of lactic acid
• ↑ Capillary permeability

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Stages of Shock
Refractory Stage
• Profound hypotension and hypoxemia
• Tachycardia worsens
• Failure of one organ system affects others
• Recovery unlikely

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Diagnostic Studies
• Thorough history and physical examination
• No single study to determine shock
• Blood studies
• Elevation of lactate
• Base deficit
• 12-lead ECG, continuous ECG monitoring
• Chest x-ray
• Hemodynamic monitoring

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Interprofessional Care
• Successful management
• Identification of patients at risk for developing shock
• Integration of patient’s history, physical examination, and clinical
findings to establish a diagnosis

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Interprofessional Care
• Successful management
• Interventions to control or eliminate cause of decreased
perfusion
• Protection of target and distal organs from dysfunction
• Provision of multisystem supportive care

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Interprofessional Care
• General management strategies
• Ensure patent is responsive
• Ensure a patent airway
• Maximize oxygen delivery
• Oxygenation
• Fluids

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Interprofessional Care
• Nutrition is vital to decreasing morbidity from shock
• Start enteral nutrition within first 24 hours
• Parenteral nutrition used only if enteral feedings contraindicated

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Interprofessional Care
Hypovolemic Shock
• Management focuses on stopping loss of fluid and restoring
the circulating volume
• Fluid resuscitation is calculated using a 3:1 rule (3 mL of
isotonic crystalloid for every 1 mL of estimated blood loss)

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Nursing Management: Shock
Nursing Assessment
• Focused assessment of tissue perfusion
• Vital signs
• Peripheral pulses
• Level of consciousness
• Capillary refill
• Skin (e.g., temperature, color, moisture)
• Urine output

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Nursing Management: Shock
Nursing Assessment
• Brief history
• Events leading to shock
• Onset and duration of symptoms
• Health history
• Medications
• Allergies
• Vaccinations, recent travel

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Nursing Management: Shock
Nursing Diagnoses
• Ineffective peripheral tissue perfusion and risk for decreased
cardiac tissue perfusion, ineffective cerebral tissue perfusion,
ineffective renal perfusion, impaired liver function, and
ineffective GI perfusion
• Anxiety

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Nursing Management: Shock
Planning
• Goals
• Evidence of adequate tissue perfusion
• Restoration of normal or baseline BP
• Recovery of organ function
• Avoidance of complications from prolonged states of
hypoperfusion

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Nursing Management: Shock
Nursing Implementation
• Health Promotion
• Identify patients at risk
• Older patients
• Those who are immunocompromised
• Those with chronic illness
• Surgery or trauma patients

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Nursing Management: Shock
Nursing Implementation
• Health Promotion
• Planning to prevent shock
• Monitoring fluid balance to prevent hypovolemic shock
• Maintenance of hand washing to prevent spread of infection

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Nursing Management: Shock
Nursing Implementation
• Acute Care
• Monitor patient’s ongoing physical and emotional status
• Identify trends to detect changes in patient’s condition
• Plan and implement nursing interventions and therapy

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Nursing Management: Shock
Nursing Implementation
• Acute Care
• Evaluate patient’s response to therapy
• Provide emotional support to patient and caregiver
• Collaborate with other members of interprofessional team to
coordinate care

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Nursing Management: Shock
Evaluation
• Adequate tissue perfusion with restoration of normal or
baseline BP
• Normal organ function with no complications from
hypoperfusion
• Decreased fear and anxiety and increased psychologic comfort

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