Transcript of Lesson 2 Physiology of Life and Death. Maintenance of Life Body systems –Interrelated...
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- Lesson 2 Physiology of Life and Death
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- Maintenance of Life Body systems Interrelated Interdependent
Every cell and every organ work together to: Sustain cellular
energy production Maintain vital metabolic processes
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- Energy Energy powers all body functions Energy sustains
cellular and organ functions Cells make energy from oxygen and
glucose Energy is stored in the form of adenosine triphosphate
(ATP) molecules Without energy, cellular functions cease The goal
is to help ensure that the patients body maintains energy
production
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- Systems and Components (1 of 2) Airway Must be patent Breathing
(lungs) Adequate oxygen must: Reach alveoli Cross
alveolar/capillary wall Enter the circulation Carbon dioxide (CO 2
) must be removed
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- Systems and Components (2 of 2) Circulation Distributes red
blood cells (RBCs) Ensures adequate number of RBCs Transports
oxygen to every cell in every organ
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- Airway (1 of 3) An open airway is essential to deliver air
(oxygen) to the alveoli
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- Airway (2 of 3) Normal air movement Inhalation results from
negative intrathoracic pressure as the chest expands Air fills the
alveoli
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- Airway (3 of 3) Normal air movement (contd) Exhalation results
from increased intrathoracic pressure as the chest relaxes Forces
air out of the alveoli
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- Breathing (Lungs) (1 of 2) When air reaches the alveoli: Oxygen
crosses the alveolarcapillary membrane Oxygen Enters the RBCs
Attaches to hemoglobin for transport
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- Breathing (Lungs) (2 of 2) CO 2 in the plasma and cells A
by-product of aerobic metabolism and energy production Crosses the
alveolarcapillary membrane into the alveoli Is removed during
exhalation
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- Circulation (1 of 2) Oxygen-enriched RBCs are pumped through
the blood vessels of the body to deliver oxygen to target
organs
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- Circulation (2 of 2) Oxygen is then off-loaded from the RBCs to
fuel the metabolic processes of the cell CO 2 is transferred from
the cells to the plasma for elimination via the lungs
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- Cellular Metabolism Aerobic (1 of 3) Aerobic metabolism Most
efficient method of energy production Uses oxygen and glucose to
produce energy via chemical reactions known as glycolysis and the
Krebs cycle Produces large amounts of energy Waste products Carbon
dioxide Water
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- Cellular Metabolism Aerobic (2 of 3) Aerobic metabolism is
dependent upon: Adequate and continuous supply of oxygen Patent
airway Functioning lungs (pulmonary system) Functional heart Pump
blood to the cells
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- Cellular Metabolism Aerobic (3 of 3) Aerobic metabolism is
dependent upon (contd): Intact vascular system Adequate supply of
RBCs Carry and transport oxygen Remove waste
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- Aerobic Metabolism
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- Cellular Metabolism Anaerobic (1 of 2) An injury that affects
any of these three components of the oxygen delivery system will
affect energy production Anaerobic metabolism is a metabolic
process that functions in the absence of oxygen
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- Metabolism without adequate oxygen Uses stored glucose in the
form of glycogen for energy production Capable of sustaining energy
requirements only for a short time Produces only small amounts of
energy 19-fold decrease in energy Increased lactic acid as a
by-product Cellular Metabolism Anaerobic (2 of 2)
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- Anaerobic Metabolism
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- Shock Inadequate energy production required to sustain life
Change from aerobic to anaerobic metabolism Secondary to
hypoperfusion Delivery of oxygen is inadequate to meet metabolic
demands Decreased energy production Cellular and organ death
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- Consequences of Hypoperfusion (1 of 4) Cellular hypoxia
Decreased ATP (energy) production Cell dysfunction Lactic acid
buildup Low pH
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- Cell dysfunction (contd) Autodigestion of cells Leads to
cellular death and organ failure Entry of sodium and water into the
cell Cellular edema (swelling) worsens with overhydration
Continuation of cycle Unless oxygenated red blood cells reach the
capillaries If further loss of intravascular (blood) volume The
cycle continues Consequences of Hypoperfusion (2 of 4)
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- Inadequate ATP Cells and organs do not function properly
Hypothermia Decreased heat production Consequences of Hypoperfusion
(3 of 4)
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- Cells and organs do not function properly Acidosis What little
ATP is being produced is used to shiver Lactic acid production
increases Coagulopathy As body temperature drops, blood clotting
becomes impaired Consequences of Hypoperfusion (4 of 4)
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- Triangle of Death
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- Cascade of Death
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- Types of Shock Shock is any condition that causes decreased
cellular energy production Hypovolemic Dehydration Hemorrhage
Distributive Neurogenic Septic Anaphylactic Psychogenic Cardiogenic
Pump failure (intrinsic versus extrinsic)
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- Trauma-Related Types of Shock Hypovolemic Dehydration
Hemorrhage Distributive Neurogenic Septic Anaphylactic Psychogenic
Cardiogenic Pump failure (intrinsic versus extrinsic)
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- Hemorrhagic Shock Most common cause of hypoperfusion after
trauma Internal or external blood loss Classes of shock
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- Neurogenic Shock Associated with spinal cord injury
Interruption of the sympathetic nervous system resulting in
vasodilation Patient has normal blood volume but vascular container
has enlarged, thus decreasing blood pressure
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- Cardiogenic Shock Extrinsic Results from external compression
of the heart Ventricles cannot fully expand Less blood is ejected
with each contraction Blood return to the heart is decreased Causes
from trauma include: Pericardial tamponade Tension
pneumothorax
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- Pathophysiology of Shock (1 of 6) Shock is progressive Changes
in shock include: Hemodynamic Cellular (metabolic) Microvascular
Compensatory mechanisms Short-term Will fail without
interventions
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- Pathophysiology of Shock (2 of 6) The heart must be an
effective pump Primed by return of blood through the vena cavae
Starlings Law Stroke volume (SV) Amount of blood ejected with each
contraction Depends on adequate return of blood If blood volume
decreases SV will decrease Cardiac output (CO) will decrease unless
the heart rate (HR) increases CO = SV HR
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- Pathophysiology of Shock (3 of 6) Adequate blood pressure
Required to maintain cellular perfusion CO is one factor in
maintaining blood pressure (BP) If CO falls Vasoconstriction occurs
Systemic vascular resistance (SVR) increases in an attempt to
maintain BP BP = CO SVR
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- Pathophysiology of Shock (4 of 6) Vasoconstriction leads to the
ischemic phase of shock Microvascular changes Early Precapillary
and postcapillary sphincters constrict Resulting in ischemia in the
tissues Must then produce energy anaerobically
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- Pathophysiology of Shock (5 of 6) As acidosis increases: The
precapillary sphincters relax The postcapillary sphincters remain
constricted This results in stagnation of blood in the capillary
bed
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- Pathophysiology of Shock (6 of 6) Finally: The postcapillary
sphincters relax Results in washout Releases microemboli Aggravates
acidosis Causes infarction of organs by microemboli
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- Signs Associated with Types of Shock
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- Organ System Failure Due to Shock If not recognized and
promptly corrected, shock will lead to organ dysfunction: First in
oxygen-sensitive organs Then in other less oxygen-sensitive organs
This cascading effect will lead to multi-organ dysfunction syndrome
and patient death Failure of one major organ system Mortality rate
of approximately 40% As additional organ systems fail, mortality
approaches 100%
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- Organ Sensitivity to Hypoxia Extremely sensitive Brain, heart,
lungs Moderately sensitive Kidneys, liver, gastrointestinal tract
Least sensitive Muscle, bone, skin
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- Organ System Failure Due to Shock (1 of 4) Acute renal failure
May result if oxygen delivery is impaired for more than 4560
minutes Will result in: Decreased renal output Reduced clearing of
toxic products
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- Acute respiratory distress syndrome (ARDS) Results from: Damage
to the alveolar cells Hyper-resuscitation (fluid overload) Results
in: Leakage of fluid into the interstitial spaces and alveoli Organ
System Failure Due to Shock (2 of 4)
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- Hematologic failure Impaired clotting cascade May result from:
Hypothermia Dilution of clotting factors from fluid administration
Depletion of clotting factors Organ System Failure Due to Shock (3
of 4)
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- Hepatic failure Results from prolonged shock Overwhelming
infection Results from decreased function of the immune system due
to ischemia and loss of energy production Organ System Failure Due
to Shock (4 of 4)
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- Summary (1 of 3) Cellular function depends on adequate energy
production Adequate energy production depends on a continuous and
adequate supply of oxygen A continuous and adequate supply of
oxygen depends on: Patent airway Functioning lungs Functioning
heart Intact circulation
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- Summary (2 of 3) Interruption of the oxygen supply for any
reason will lead to anaerobic metabolism Anaerobic metabolism
provides insufficient energy to sustain cellular function for any
length of time This leads to cellular dysfunction and cell death,
organ dysfunction and organ death, and ultimately patient
death
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- Summary (3 of 3) Knowledge, understanding, and early
recognition of impaired energy production resulting from airway
compromise, pulmonary injury, and impaired circulation are key to
early recognition of shock. Prompt intervention by prehospital care
providers to correct these conditions can prevent the cascade of
cellular dysfunction that leads to organ death. This will improve
the survival rate for victims of traumatic injury.
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- Questions?