PATHOPHYSIOLOGY OF SHOCK

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PATHOPHYSIOLOGY OF SHOCK
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FLUIDS AND ELECTROLYTES

• WATER
• Most abundant substance in the body
• Accounts for 60 of total body weight
• Distributed among compartments separated by cell
  membranes

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INTRACELLULAR COMPARTMENT

• Fluid within body cells
• Represents 75 of all body water

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EXTRACELLULAR COMPARTMENTS

• Fluid found outside body cells
• Represents 25 of all body water
• Has two divisions
• Intravascular
• Fluid found outside of cells within the
  circulatory system
• Represents 7.5 of body water
• Interstitial
• Fluid outside of cells and not in circulatory
  system
• Represents 17.5 of body water
• CSF, intraocular fluid

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HYDRATION

• Water is the universal solvent
• Most substances dissolve in water, producing
  various chemical changes
• Water is critical for most of bodys biochemical
  processes
• Normal hydration balance

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INTAKE

• Defined as the water coming into the body
• From digestive system (liquids, solid foods,) and
  metabolic sources.

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OUTPUT

• Defined as all water excreted from the body
• From lungs, kidneys, skin, intestines water
  vapor, urine, perspiration, and feces

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HOMEOSTASIS

• The bodys tendency to maintain a constant,
  stable internal environment.

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HOMEOSTASIS

• When fluid levels drop
• ADH (Anti-diuretic hormone) secreted
• Kidneys reabsorb more water back into the blood
  and excrete less urine
• Thirst sensation stimulates urge to drink

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HOMEOSTASIS

• When fluid levels rise
• Kidneys activated to excrete more urine
• Water shifts from one compartment to another

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DEHYDRATION

• An abnormal decrease in total body water (loss of
  water and electrolytes)

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CAUSES OF DEHYDRATION

• GI losses
• Vomiting
• Diarrhea
• Malabsorption disorders

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CAUSES OF DEHYDRATION

• Increased insensible loss
• Fever
• Hyperventilation
• High environmental temperatures

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CAUSES OF DEHYDRATION

• Increased sweating
• Medical conditions
• High environmental temperatures

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CAUSES OF DEHYDRATION

• Internal loss - loss of fluids into various body
  compartments, especially from intravascular into
  interstitial.
• Illness - peritonitis, pacreatitis, bowel
  obstruction
• Poor nutritional states

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CAUSES OF DEHYDRATION

• Plasma losses
• Burns
• Surgical drains
• Fistulas (Abnormal tubelike passage from a normal
  cavity to another cavity or free standing
  surface).
• Open wounds

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CLINICAL PRESENTATION

• Dry mucous membranes
• Poor skin turgor
• Excessive thirst
• If severe, tachycardia and hypotension
• In infants, sunken fontanelles, absence of tears,
  dry diaper, concentrated urine

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MANAGEMENT - DEHYDRATION

• Fluid replacement - isotonic crystalloid (100-200
  ml/hr)

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OVERHYDRATION

• Excess of total body water

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CLINICAL PRESENTATION

• Peripheral edema
• Heart failure, lung congestion

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MANAGEMENT

• Remove excess fluid
• IV D5W TKO
• Diuretic therapy

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ELECTROLYTES

• BASICS
• Defined as substances that dissociate into
  charged particles when placed in water
• Positively charged particles are cations
• Negatively charged particles are anions
• Usually measured in milliequivalents per liter (
  mEq/L)

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MOST FREQUENTLY OCCURRING CATIONS
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SODIUM (Na)

• Most abundant extracellular cation
• Helps regulate water distribution
• Helps transmit nerve impulses
• Hypernatremia - increase in relative amount of
  sodium in body
• Hyponatremia - decrease in relative amount of
  sodium in body

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POTASSIUM (K)

• Most abundant intracellular cation
• Helps transmit electrical impulses
• Hyperkalemia - high potassium level
• Hypokalemia - low potassium level

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CALCIUM (Ca)

• Helps in muscle contractions
• Helps in nerve impulse transmission
• Hypercalcemia - high calcium level
• Hypocalcemia - low calcium level

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MAGNESIUM (Mg)

• Necessary for many biomechanical functions
• Helps in carbohydrate metabolism

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MOST FREQUENTLY OCCURRING ANIONS
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CHLORIDE (Cl-)

• Closely associated with sodium
• Helps to regulate fluid balance and renal function

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BICARBONATE (HCO-3)

• Chief buffer in the body
• Neutralizes hydrogen (H) ion and other organic
  acids

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PHOSPHATE (HPO-4)

• Important for energy stores
• Intracellular buffer
• Helps in renal function

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OTHER NEGATIVE COMPOUNDS

• Proteins
• Certain organic acids

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NONELECTROLYTES

• Molecules that do not dissociate into ions
• Glucose
• Urea

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OSMOSIS AND DIFFUSION

• Basic mechanics
• Fluid compartments are separated by
  semi-permeable membranes (pores)
• Certain materials are allowed to pass through
  freely ( oxygen, carbon dioxide, water)
• Larger compounds are restricted ( proteins, large
  sugars )
• Natural body tendency is to keep solutions on
  both sides of membrane in balance (isotonic)

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OSMOSIS

• If one side of the membrane has a higher solute
  concentration than the other side, a pressure
  gradient occurs ( pulling force)
• Water moves from the side of lower concentration
  (hypotonic) to the side of higher concentration
  (hypertonic) until both sides are equal

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DIFFUSION

• If one side of the membrane has a higher solute
  concentration than the other side, the body again
  seeks to restore balance through redistribution
  of electrolytes
• Electrolytes will move from hypertonic to
  hypotonic side until isotonic relationship is
  reestablished
• Movement direction in diffusion is opposite that
  in osmosis

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OTHER TRANSPORT MECHANISMS
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ACTIVE TRANSPORT

• Movement of molecules against the gradient e.g..
  sodium - potassium pump
• Electrical impulses of the heart (automaticity)
• Faster than diffusion
• Requires expenditure of energy

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FACILITATED DIFFUSION

• Substance transported across membranes by helper
  proteins (Glucose/Insulin relationship)
• May require expenditure of energy
• Must follow gradient

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INTRAVENOUS THERAPY

• Basics
• Defined as the introduction of fluids and other
  substances into the venous side of circulatory
  system
• Purpose
• Replace blood lost through hemorrhage
• Replace lost electrolytes or fluids
• Introduce medications directly into vascular
  system

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BLOOD AND ITS COMPONENTS
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BLOOD

• Fluid of the cardiovascular system
• Adequate amount required for transport of
  nutrients, oxygen, hormones, and heat
• Made up of liquid portion - plasma - and formed
  elements - blood cells

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PLASMA

• Composition - 92 water, 6 -7 proteins
• Viscosity is determined by ratio of plasma to
  cells

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FORMED ELEMENTS INCLUDE

• Erythrocytes
• Leukocytes
• Thrombocytes

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ERYTHROCYTES

• Red blood cells, which make up 99 of all blood
  cells
• Contain hemoglobin to carry oxygen
• Make up 45 of total blood volume
• Hematocrit is the percentage of red blood cells
  in blood

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LEUKOCYTES

• White blood cells, responsible for immunity and
  fighting infection

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THROMBOCYTES

• Platelets, necessary for clotting

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BLOOD TYPES

• Blood types determined by presence of antigens on
  erythrocytes
• Major classification system is ABO system

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ABO SYSTEM

• Two major antigen types, A and B
• People can have either one or the other, both or
  neither
• People generally can receive only blood of their
  type
• Different type of blood sets off immune response
• Type O blood does not have antigens to type A or
  type B people with it are universal donors
• Type AB blood does not have antibodies to either
  A or B people with it are universal recipients

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Rh FACTOR

• Present in 85 of the population
• Others are sensitized through transfusion and
  have formed antibodies and may have fatal
  reactions with additional transfusions

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FLUID REPLACEMENT

• Whole blood
• Best, most natural replacement
• Contains hemoglobin for oxygen transport
• Impractical in prehospital arena
• Must be typed and cross-matched

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FLUID REPLACEMENT

• Fractionated blood parts
• Packed red blood cells
• Must be typed and cross-matched
• Fresh frozen plasma
• Does not require cross-matching

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TRANSFUSION REACTION

• Blood and blood products not used by EMS
  personnel in field
• Personnel must, however, recognize reaction of
  recipient to blood or blood products of
  incompatible type
• Clinical presentations
• Fever, chills, hives, hypotension, tachycardia,
  flushing of skin, headaches, nausea, loss of
  consciousness, vomiting

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MANAGEMENT

• Stop the infusion immediately
• Replace the blood with crystalloid solution
• Conduct rapid but adequate assessment of mental
  status
• Administer oxygen
• Contact medical control

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Fluid overload and congestive heart failure
secondary to transfusion
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CLINICAL PRESENTATION

• Increased dyspnea, pulmonary congestion, edema,
  altered mental status
• Management
• Stop infusion
• Administer crystalloid at TKO rate
• Administer oxygen
• Contact medical control

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INTRAVENOUS FLUIDS

• Colloids
• Contain proteins or large molecules
• Remain longer in the intravascular compartment
• Increases intravascular volume through osmosis
• Examples Plasmanate salt-poor albumin dextran
  hetastarch
• Colloids are expensive and have a short shelf
  life, impractical for prehospital use

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CRYSTALLOIDS

• Solutions containing no proteins
• Classified by tonicity ( number of particles
  present per unit volume)

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CRYSTALLOIDS

• Isotonic
• Electrolyte composition similar to blood plasma
• Will not cause significant fluid or electrolyte
  shift

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CRYSTALLOIDS

• Hypertonic
• Have higher solute concentration than cells
• Will tend to cause fluid shift out of
  intracellular and into extracellular compartment

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CRYSTALLOIDS

• Hypotonic
• Have lower solute concentration than cells
• Will tend to cause fluid shift out of
  extracellular and into intracellular compartment

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COMMON CRYSTALLOID SOLUTIONS

• Lactated Ringers
• Isotonic
• Used for fluid volume replacement
• Normal Saline
• Isotonic
• Used for fluid volume replacement

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COMMON CRYSTALLOID SOLUTIONS

• D5W
• Hypotonic
• Used TKO and to supply calories for cell
  metabolism

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