Shock

Week 13 Care of Patients in Shock

• Shock: Impaired oxygen delivery to tissues.
• Aerobic metabolism uses oxygen.
• Anaerobic metabolism occurs without oxygen, leading to lactic acidosis.
• Lactic acidosis: Develops when lactate production exceeds its metabolism. This occurs when tissue oxygenation is inadequate.
• Shock Causes:
  • Blood loss
  • History of stroke and on anticoagulants
  • History of heart attack and on antiplatelets
  • MAP (mean arterial pressure) 70-110 mmHg for adequate perfusion.
  • Doppler: Used when diastolic pressure is not obtainable; it provides systolic pressure over Doppler measurement. (RELISTEN!!)
• Stages of Shock (Hemorrhagic):
  • Initial stage: Loss of 750 cc of blood.

Shock Compensation

• Body Compensation:
  • Minimal tachycardia (heart rate 110).
  • Normal or increased pulse pressure indicates effective heart contraction.
  • Measuring pulse pressure (systolic minus diastolic): 40-60 mmHg normal range, if higher, stiffer arteries.
  • Atherosclerosis: Shows how well the heart contracts. High blood pressure stiffens vessels requiring greater force for blood pumping.
  • Non-progressive (compensatory) stage: MAP decreases by 10-15 mmHg. More than 750-1500 cc of blood loss leads to anxiety and restlessness.
  • Loss of oxygen triggers adrenal medulla stimulation. Epinephrine and norepinephrine elevate heart rate and blood pressure. Kidneys try to conserve water (less than 30 cc of urine), and antidiuretic hormone is secreted.

Shock Progression

• Sensing Blood Concentration: The body senses concentrated blood and reabsorbs more water, decreasing blood concentration. This process decreases oxygen to non-vital organs.
• Shunting Blood Blood is redirected to vital organs (brain, heart, and liver) from non-vital organs during shock. This may not damage non-vital organs.
• Anaerobic Effect/Acidosis: Production of lactic acid in the cells. If interventions are not provided, this is reversible.
• Progressive Stage: Sustained MAP decrease greater than 20 mmHg (1500-2000 cc blood loss). Heart rate above 120 bpm, diastolic filling time compromised. RR (respiratory rate) 30-40/minute (tachypnea). Narrowed pulse pressure leads to decreased perfusion to vital organs and hypoxia (low oxygen).

Life-Threatening Emergency/Refractory Stage

• Emergency: Immediate interventions are needed within one hour of progressive shock.
• Refractory Stage: Too little oxygen reaches tissues resulting in too much cell death and damage from blood loss exceeding 2 liters, leading to lethargy and sleepiness.
• Severe Hypotension: Cool skin due to body shunting blood to vital organs. Shock continues, inability to respond to interventions.
• Multiple Organ Dysfunction Syndrome (MODS): Metabolites released from dead cells; microthrombi throughout the body.
• MODS First Occurs in: Liver, heart, brain, and kidney.

Shock Classification/Types

• Hypovolemic Shock: Intravascular volume decreased.

• Obstructive Shock:

  • Problems impairing normal heart muscle function for effective blood pumping.
    • Causes:
      • Pulmonary embolism (blood clot in pulmonary vasculature).
      • Cardiac tamponade (fluid buildup around heart).

• Distributive Shock:

  • Blood volume not lost but distributed to interstitial space.
  • Loss of sympathetic tone, dilated vessels, blood pooling, capillary leakage. -Discoloration of extremities.
    • Septic, anaphylactic, and neurogenic shock - characterized by vasodilation.
      • Shock and WBC low, body cannot fight infections.
      • Organ failure (sepsis).
      • Microthrombi formation, Amplified inflammatory response (body-wide). Anaerobic metabolism continues.
      • Local infection, can become systemic, systemic infection (bacteremia). Caused by gram-negative (E. coli), and gram-positive (staphylococcus).

• Cardiogenic Shock:

  • Problems with left, right, or both ventricles (actual heart muscle is unhealthy).
  • High left ventricular pressure forces fluid from lungs to interstitial space. Myocardial infarction is the leading cause (direct pump failure). Normal pressures (left) are 6-12, and right is 2-5
  • Dilated vessels lead to the heart using less oxygen.
  • Clinical manifestations: Tachycardia, decreased cardiac output, decreasing blood pressure, narrowing pulse pressure, and crackles.

Treatment Aspects

• First-Line Treatment: Isotonic solutions (e.g., normal saline, lactated ringers).

• Blood Products: Replaced blood loss; avoid glucose-containing blood products to prevent clots.

• Cardiogenic Shock Treatment: Beta adrenergic agonists.

• Vasodilators: Decrease workload by decreasing preload and afterload (force heart pumps against) to increase blood flow to the circulatory system.

  • Medications: nitroprusside, nitroglycerin.
  • Intra-aortic balloon pump (IABP).

• Obstructive Shock:

  • Pulmonary Embolism: Heparin, Fibrinolytic therapy (streptokinase, alteplase).
  • Cardiac Tamponade: Pericardiocentesis.

This quiz covers the fundamental aspects of patient care in shock, including the types of metabolism affected, causes, and stages of hemorrhagic shock. It emphasizes the body's compensatory mechanisms and the importance of monitoring parameters like MAP and pulse pressure. Test your understanding of these critical concepts for effective patient management.