Transcript AEMT Transition - Unit 9 - Blood and Vascular Physiology

TRANSITION SERIES
Topics for the Advanced EMT
CHAPTER
9
Blood, Cardiac Function,
and Vascular System
Objectives
• Identify the components of blood
volume.
• Identify the roles of hydrostatic
pressure and plasma oncotic pressure.
• Determine the variables that play into
cardiac output.
Objectives (cont’d)
• Identify the variables that affect
systemic vascular resistance.
• Discuss roles of the autonomic nervous
system in perfusion.
Introduction
• Multiple variables must interact in just
a certain way for normal perfusion:
– Oxygen
– Alveoli
– Cardiac function
– Systemic vascular resistance
– Blood volume and its components
Blood Volume
• Composition of blood
– Formed elements (45%)
 RBC
 WBC
 Platelets
– Plasma (55%)
 91% water
 Albumin, antibodies, clotting factors
Blood Volume (cont’d)
• Distribution of blood
– Arteries
– Veins
– Organs
Distribution of Blood in the Cardiovascular System
Blood Volume (cont’d)
• Hydrostatic pressure
– Created by myocardial contraction and
vasoconstriction.
– Forces fluid out of the vascular space.
– Disturbances can create emergencies.
Blood Volume (cont’d)
• Plasma oncotic pressure
– The force exerted by large plasma
proteins in blood vessels.
– Helps to keep fluid in the vascular
space.
Blood Volume (cont’d)
• Effects of hydrostatic or oncotic
pressure changes
– High hydrostatic pressure
– Low hydrostatic pressure
– High oncotic pressure
– Low oncotic pressure
Hydrostatic pressure pushes water out of the capillary. Plasma oncotic
pressure pulls water into the capillary.
Pump Function of the Myocardium
• Heart must work effectively
– Cardiac output
 Heart rate and stroke volume
– Stroke volume
 Preload
 Contractility
 Afterload
Pump Function of
the Myocardium (cont’d)
• Disturbances can cause emergencies
– Decrease/Increase
– Decrease/Increase
– Decrease/Increase
contractility
– Decrease/Increase
– Decrease/Increase
tone
in heart rate
in blood volume
in ventricular
in sympathetic tone
in parasympathetic
Systemic Vascular Resistance
• Systemic vascular resistance (SVR)
– Resistance offered to the flow of blood
through a vessel
 Vasoconstriction
 Vasodilation
– Effects of changes in autonomic tone
 Sympathetic
 Parasympathetic
Systemic Vascular
Resistance (cont’d)
• SVR and pulse pressure
– Effects of vasoconstriction
– Effects of vasodilation
– Pulse pressure changes
 Normal pulse pressures
 Abnormal pulse pressures
Microcirculation
• Microcirculation
– Flow of blood through the smallest of
blood vessels
 Arterioles
 Venules
 Capillary beds
– Regulatory influences
Microcirculation is the flow of blood through the smallest blood vessels:
arterioles, capillaries, and venules. Precapillary sphincters control the flow of
blood through the capillaries.
Blood Pressure
• Blood pressure
– Measure of cardiac output
 B/P = CO x SVR
– Both cardiac output and systemic
vascular resistance have direct effect on
blood pressure
Blood Pressure (cont’d)
• Effect of baroreceptors and
chemoreceptors
– Baroreceptors
 Detect blood pressure
– Chemoreceptors
 Detect blood chemistry (O2, CO2, H+)
Case Study
• You are dispatched for a patient with a
“chest injury” at 0230 hrs. Dispatch
information was lacking due to the
caller being hysterical and difficult to
understand. As a precaution, PD and FD
are also dispatched to the same
residence. When you roll up on scene,
8-10 people are crowded around the
front door of the home.
Case Study (cont’d)
• Scene Size-Up
– Standard precautions taken
– PD not on scene yet, entry blocked due
to crowd of people
– Unknown age of the patient
– MOI is a suspected chest injury
– An ALS FD is responding behind you
Case Study (cont’d)
• What are your immediate concerns at
this time?
• Given the presence of EMS and FD,
should the house be approached?
Case Study (cont’d)
• PD arrives on scene and quickly
disperses the crowd of people on the
porch. They wave you inside and as
you approach an officer tells you that
the patient is unresponsive inside. The
“story” they get is that the male was
cleaning his guns when one accidently
discharged, resulting in the patient
shooting himself.
Case Study (cont’d)
• Primary Assessment Findings
– Mid-20s age, male patient
– Patient unresponsive, blood-soaked
shirt
– Pupils slow to respond to light
– Slight inspiratory snoring noted with
breathing
Case Study (cont’d)
• Primary Assessment Findings
– Respirations rapid and shallow
– Carotid pulse 120/min, peripheral pulse
absent
– Peripheral skin cool and clammy
Case Study (cont’d)
• How would you prioritize this patient?
• What are the patient's life threats, if
any?
• What care should be administered
immediately?
Case Study (cont’d)
• Medical History
– Unknown
• Medications
– Unknown
• Allergies
– Unknown
Case Study (cont’d)
• Pertinent Secondary Assessment
Findings (continued)
– Pupils sluggish to respond, membranes
dry
– Airway patent with manual technique
– Breathing shallow, no right side breath
sounds
– Central pulse present, peripheral absent
Case Study (cont’d)
• Pertinent Secondary Assessment
Findings (continued)
– Skin is pale, cool, and clammy
– Open GSW injury to right chest
– B/P 108/86, HR 110, Resp 24 and
shallow
– No other indications of trauma noted
Case Study (cont’d)
• What are the reasons for the following
findings?
– Altered mental status
– Disturbance to breath sounds
– Tachycardia
– Pulse pressure
– Skin characteristics
Case Study (cont’d)
• Care provided:
– Patient immobilized as a precaution
– High-flow oxygen with PPV
– Occlusive dressing applied to GSW site
– Initiate intravenous access
– Emergent transport to the hospital
Summary
• Along with the body maintaining
oxygenation, it must also provide for
adequate peripheral perfusion.
• In situations of poor peripheral
perfusion, blood will be shunted to the
core organs.
• Early identification of a failing cardiovascular system underscores the need
for rapid transport to the hospital.