Pathophysiology part 1

Disease—Causes and
Pathophysiology

Part 1 Topics

 Disease Risk
 Hypoperfusion
 Shock
 Multiple Organ Dysfunction
Syndrome

Genetics
and
Other
Causes of
Disease

Many factors combine to cause
disease. (1 of 3)
 Genetics
 Environment
 Life-style
 Age
 Gender

disease. (2 of 3)
 Inherited traits are determined
by molecules of
deoxyribonucleic acid (DNA).
 Each somatic cell contains
46 chromosomes.
 Sex cells contain 23
chromosomes.

disease. (3 of 3)
 An offspring receives 23
chromosomes from the mother and
23 chromosomes from the father.
 One or more chromosomes may be
abnormal and may cause a
congenital disease or a propensity
toward acquiring a disease later
in life.

Most disease processes are
multifactorial in origin.

Disease Effects on Individuals

Clinical Factors
 Host
 Agent
 Environment

Disease Effects on Populations

Epidemiological Factors
 Incidence
 Prevalence
 Mortality

Family History and
Associated Risk Factors

Immunologic Disorders

 A number of immunologic
disorders are more prevalent
among those with a family
history of the disorder.

Cancer

 Some types of cancer tend to
cluster in families and seem to
have a combination of genetic
and environmental causes.
 Breast cancer
 Colorectal cancer

Endocrine Disorders
 The most common endocrine
disorder is diabetes mellitus.
 Leading cause of:
 Blindness
 Heart disease
 Kidney failure
 Premature death
 Both Type I and Type II diabetes can
be family related.

Hematologic Disorders
 There are many causes of
hereditary hematological
disorders such as gene
alteration and histocompatibility
(tissue interaction)
dysfunctions.
 Hemophilia
 Hemochromatosis

Cardiovascular Disorders
 The cardiovascular system can be
greatly affected by genetic disorders.
 Elongation of the QT interval.
 Mitral valve prolapse.
 Coronary artery disease.
 Hypertension.
 Cardiomyopathy.

Renal Disorders
 Caused by a variety of factors,
primarily hypertension.
 EMS is increasingly being called
upon to deal with complications of
dialysis including:
 Problems with vascular access
devices
 Localized infection and sepsis
 Electrolyte imbalances

Rheumatic Disorders
 Gout is a disorder both genetic and
environmental characterized by the
deposit of crystals in the joints,
most commonly the great toe.
 The crystals form as a result of
abnormally high levels of uric acid
in the blood.

Gastrointestinal Disorders
 Lactose intolerance
 Crohn’s disease
 Peptic ulcers
 Cholecycstitis
 Obesity

Neuromuscular Disorders

 Diseases of the nervous and
muscular systems include:
 Huntington’s disease
 Multiple sclerosis
 Alzheimer’s disease

Psychiatric Disorders

 Genetic and biological causes of
these disorders are being studied
and increasingly understood.
 Schizophrenia
 Manic-depressive illness (Bipolar
disorder)

Hypoperfusion (shock)
is inadequate perfusion
of body tissues.

Shock occurs first at the
cellular level and progresses
to the tissues, organs, organ
systems, and ultimately the
entire organism.

Components of the Circulatory
System (1 of 2)
 The pump (heart)
 The fluid (blood)
 The container (blood vessels)
Any problem with the
components can lead to
inadequate perfusion.

Components of the Circulatory
System (2 of 2)

The Pump

 The heart is the pump of the
cardiovascular system.
 Receives blood from the
venous system, pumps it to the
lungs for oxygenation, and then
pumps it to the peripheral
tissues.

Stroke Volume (1 of 2)

 The amount of blood ejected by
the heart in one contraction.

Stroke Volume (2 of 2)

 Factors affecting stroke volume:
 Preload—amount of blood delivered to
the heart during diastole.
 Cardiac contractile force—the strength
of contraction of the heart.
 Afterload—the resistance against
which the ventricle must contract.

The Frank-Starling mechanism states
that the greater the stretch of cardiac
muscle, up to a certain point, the
greater the force of cardiac
contraction.

Contractile Force

Is affected by circulating
hormones called catecholamines.
 Epinephrine – “Fight or Flight”
 Norepinephrine - Vasoconstriction

Cardiac Output

 Cardiac output is the amount of
blood pumped by the heart in
one minute.
Stroke volume x Heart rate = Cardiac output

Blood Pressure

 Peripheral vascular resistance is
the pressure against which the
heart must pump.
Blood Pressure = Cardiac Output x
Peripheral Vascular Resistance

The Fluid
 Blood is thicker and more adhesive than
water.
 Consists of plasma and the formed elements.
 Red cells, white cells, platelets
 Transports oxygen, carbon dioxide,
nutrients, hormones, metabolic waste
products, and heat.
 An adequate amount is needed for perfusion,
and must be adequate to fill the container.

The Container (1 of 2)
 Blood vessels serve as the container
of the cardiovascular system.
 Under control of the autonomic
nervous system they can adjust their
size and selectively reroute blood
through microcirculation.
 Microcirculation is comprised of the
small vessels: arterioles, capillaries,
and venules.

The Container (2 of 2)
 Capillaries have a sphincter between
the arteriole and capillary called the
pre-capillary sphincter.
 The pre-capillary sphincter
responds to local tissue demands
such as acidosis and hypoxia, and
opens as more blood is needed.

Blood Flow Regulation

 Peripheral vascular resistance.
 Pressure within the system.

Post-capillary Sphincter

 At the end of the capillary between
the capillary and venule is the post-
capillary sphincter.
 The post-capillary sphincter opens
when blood needs to be emptied
into the venous system.

The Fick Principle (1 of 2)

 The movement and utilization of
oxygen in the body is dependent
upon the following conditions:
 Adequate concentration of inspired oxygen.
 Appropriate movement of oxygen across the
alveolar/ capillary membrane into the arterial
bloodstream.

The Fick Principle (2 of 2)
 Adequate number of red blood
cells to carry the oxygen.
 Proper tissue perfusion.
 Efficient off-loading of oxygen
at the tissue level.

Oxygen-Hemoglobin
Dissociation Curve

The Pathophysiology of
Hypoperfusion

Causes of Hypoperfusion
(1 of 3)

 Inadequate pump
 Inadequate preload.
 Inadequate cardiac contractile
strength.
 Excessive afterload.

(2 of 3)

 Inadequate fluid
 Hypovolemia.

(3 of 3)

 Inadequate container
 Dilated container without change in
fluid volume (inadequate systemic
vascular resistance).
 Leak in the container.

Shock at the Cellular Level

 Shock causes vary, however the
ultimate outcome is impairment
of cellular metabolism.

Impaired Use of Oxygen

 When cells don’t receive
enough oxygen or cannot use it
effectively, they change from
aerobic to anaerobic
metabolism.

Glucose breakdown. (A) Stage one, glycolysis, is anaerobic (does
not require oxygen). It yields pyruvic acid, with toxic by-
products such as lactic acid, and very little energy. (B) Stage two
is aerobic (requires oxygen). In a process called the Krebs or
citric acid cycle, pyruvic acid is degraded into carbon dioxide and
water, which produces a much higher yield of energy.

Compensation and Decompensation

 Usually the body is able to
compensate for any changes.
However when the various
compensatory mechanisms fail,
shock develops and may
progress.

Compensation Mechanisms
 The catecholamines epinephrine
and norepinephrine may be
secreted.
 The renin-angiotensin system aids
in maintaining blood pressure.
 Another endocrine response by the
pituitary gland results in the
secretion of anti-diuretic hormone
(ADH).

Shock Variations (1 of 3)

 Compensated shock is the early
stage of shock during which the
body’s compensatory mechanisms
are able to maintain normal
perfusion.


 Decompensated shock is an
advanced stage of shock that
occurs when the body’s
compensatory mechanisms
no longer maintain normal
perfusion.


 Irreversible shock is shock that
has progressed so far that the
body and medical intervention
cannot correct it.

Types of Shock
 Cardiogenic
 Hypovolemic
 Neurogenic
 Anaphylactic
 Septic

Cardiogenic Shock
 The heart loses its ability to supply
all body parts with blood.
 Usually the result of left ventricular
failure secondary to acute
myocardial infarction or CHF.
 Many patients will have normal
blood pressures.

Evaluation
 The major difference between
cardiogenic shock and other types of
shock is the presence of pulmonary
edema causing:
 Difficulty breathing.
 As fluid levels rise, wheezes, crackles, or
rales may be heard.
 There may be a productive cough with
white or pink-tinged foamy sputum.
 Cyanosis, altered mentation, and
oliguria.

Treatment (1 of 2)
 Assure an open airway.
 Administer oxygen.
 Assist ventilations as
necessary.
 Keep the patient warm.

Treatment (2 of 2)
 Elevate the patient’s head and
shoulders.
 Establish IV access with minimal
fluid administration.
 Monitor the heart rate.
 Dopamine or dobutamine may be
administered.

Hypovolemic Shock
 Shock due to loss of intravascular fluid.
 Internal or external hemorrhage.
 Trauma.
 Long bones or open fractures.
 Dehydration.
 Plasma loss from burns.
 Excessive sweating.
 Diabetic ketoacidosis with
resultant osmotic diuresis.

Evaluation (Signs 1 of 2)

 Altered level of consciousness.
 Pale, cool, clammy skin.
 Blood pressure may be normal,
then fall.

Evaluation (Signs 2 of 2)

 Pulse may be normal then
become rapid, finally slowing
and disappearing.
 Urination decreases.
 Cardiac dysrhythmias may
occur.

Treatment
 Airway control.
 Control severe bleeding.
 Keep the patient warm.
 Administer a bolus of
crystalloid solution for fluid
replacement.
 PASG if part of local protocol.

Colloids

 Colloids remain in intravascular
spaces for an extended period of
time and have oncotic force.
 Plasma protein fraction (Plasmanate).
 Salt-poor albumin.
 Dextran.
 Hetastarch (Hespan).

Crystalloids

 Crystalloid solutions are the
primary compounds used in
prehospital care.
 Isotonic solutions.
 Hypertonic solutions.
 Hypotonic solutions.

The effects of
hypertonic,
isotonic, and
hypotonic
solutions
on red blood
cells.

Most Commonly Used
Solutions in Prehospital Care

Solution Tonicity
Lactated Ringer’s Isotonic
Normal Saline Isotonic
D5W Hypotonic

Transfusion reactions occur when
there is a discrepancy between
the blood type of the patient and
the type of the blood being
transfused.

Signs and Symptoms of
Transfusion Reactions
 Fever  Flushing of the skin
 Chills  Headache
 Hives  Loss of
 Hypotension consciousness
 Palpitations  Nausea
 Tachycardia  Vomiting
 Shortness of breath

Treatment of Transfusion
Reactions (1 of 2)
 IMMEDIATELY stop the
transfusion.
 Save the substance being
transfused.
 Rapid IV infusion.

Treatment of Transfusion
Reactions (2 of 2)
 Assess the patient’s mental
status.
 Administer oxygen.
 Contact medical direction.
 Be prepared to administer
mannitol, diphenhydramine, or
furosemide.

Neurogenic Shock

 Results from injury to brain or
spinal cord causing an interruption
of nerve impulses to the arteries.
 The arteries dilate causing relative
hypovolemia.
 Sympathetic impulses to the adrenal

glands are lost, preventing the
release of catecholamines with their
compensatory effects.

Evaluation

 Warm, dry, red skin.
 Low blood pressure.
 Slow pulse.

Treatment
 Airway control.
 Maintain body temperature.
 Immobilization of patient.
 Consider other possible causes
of shock.
 IV access and medications that
increase peripheral vascular
resistance.

Anaphylactic Shock
 A severe immune response to a
foreign substance.
 Signs and symptoms most often
occur within a minute, but can take
up to an hour.
 The most rapid reactions are in
response to injected substances:
 Penicillin injections.
 Bees, wasps, hornets.

Evaluation (1 of 2)

 Because immune responses can
affect different body systems, signs
and symptoms vary widely:
 Skin:
 Flushing, itching, hives, swelling, cyanosis.
 Respiratory system:
 Breathing difficulty, sneezing, coughing, wheezing,
stridor, laryngeal edema, laryngospasm.

Evaluation (2 of 2)
 Cardiovascular system:
 Vasodilation, increased heart rate, decreased
blood pressure.
 Gastrointestinal system:
 Nausea, vomiting, abdominal cramping,
diarrhea.
 Nervous system:
 Altered mental status, dizziness, headache,
seizures, tearing.

Treatment
 Airway protection, may include
endotracheal intubation.
 Establish an IV of crystalloid
solution.
 Pharmacological intervention:
 Epinephrine, antihistamines,
corticosteroids, vasopressors,
inhaled beta agonists.

Septic Shock
 An infection that enters the
bloodstream and is carried
throughout the body.
 The toxins released overcome the
compensatory mechanisms.
 Can cause the dysfunction of an
organ system or result in multiple
organ dysfunction syndrome.

Evaluation
The signs and symptoms are
progressive.
 Increased to low blood pressure.
 High fever, no fever, or hypothermic.
 Skin flushed, pale, or cyanotic.
 Difficulty breathing and altered lung
sounds.
 Altered mental status.

Treatment
 Airway control.
 IV of crystalloid solution.
 Dopamine to support blood
pressure.
 Monitor heart rhythm.

Multiple Organ Dysfunction
Syndrome
 MODS is the progressive
impairment of two or more
organ systems from an
uncontrolled inflammatory
response to a severe illness
or injury.

Primary MODS
 Organ damage results directly from
a specific cause such as ischemia
or inadequate tissue perfusion from
shock, trauma, or major surgery.
 Stress and inflammatory responses
may be mild and undetectable.
 During this response, neutrophils,
macrophages, and mast cells are
thought to be “primed” by cytokines.

Secondary MODS
 The next time there is an injury,
ischemia, or infection the “primed”
cells are activated, producing an
exaggerated inflammatory response.
 The inflammatory response enters a
self-perpetuating cycle causing
damage and vasodilation.
 An exaggerated neuroendocrine
response is triggered causing further
damage.

MODS 24 Hours After
Resuscitation
 Low grade fever.
 Tachycardia.
 Dyspnea.
 Altered mental status.
 General hypermetabolic,
hyperdynamic state.

MODS Within 24 to 72 Hours

 Pulmonary failure begins.

MODS Within 7 to 10 Days

 Hepatic failure begins.
 Intestinal failure begins.
 Renal failure begins.

MODS Within 14 to 21 Days

 Renal and hepatic failure
intensify.
 Gastrointestinal collapse.
 Immune system collapse.

MODS After 21 Days
 Hematologic failure begins.
 Myocardial failure begins.
 Altered mental status resulting
from encephalopathy.
 Death.

Pathophysiology part 1

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Pathophysiology part 1

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