cardiovascular assessment ii yuriy slyvka md, phd
TRANSCRIPT
Cardiovascular Assessment II
Yuriy Slyvka MD, PhD
Cardiovascular Assessment
Cardiac Output• Blood Pressure–Systolic / Diastolic
• Pulse Perfusion
Blood Pressure
Systolic - Normal 95 - 140 mmHg Diastolic - Normal 60 - 90 mmHg Children vary with age Neonate 60 - 90 over 30 - 60
mmHg
Systolic
Maximum pressure exerted on arterial wall during ventricular contraction
Diastolic
Pressure in vasculature during ventricular relaxation
Indirect Blood Pressure Measurement via Cuff
Wrap blood pressure cuff around upper arm
Auscultate over artery in antecubital fossa
Inflate cuff rapidly Deflate cuff slowly while listening
Mechanism Cuff inflated - occludes artery - no
sound Slowly deflate cuff - first sound =
systolic Continue to deflate cuff until sound
disappears = diastolic Tapping sounds heard with each
heart beat called Korotkoff’s sounds (Ko rot kof)
Technique
Usually use non-dominant arm Inflate to approx 160 mmHg Drop pressure approximately 3
mmHg/sec Standard adult cuff 5 inches wide Pediatric 3 inches wide
Sources of Error Resulting in High BP Measurements
Cuff too narrow• Width of cuff approx 40% circumference
of arm Applied too tight or too loose Excessive cuff pressure
• should start 30 mmHg above systolic Pressing stethoscope too tightly over
artery will affect diastolic pressure
Hypertension
BP persistently > 140-160 / 90 Secondary means cause is known
• May be a side-effect of medication
Primary Hypertension means cause is unknown
Hypotension BP < 95 / 60 Late sign of hypovolemia, cardiac
failure, shock 90 / 60 not uncommon in young
females
Low blood pressure results in inadequate perfusion
Brain Heart - (70% coronary artery
perfusion occurs during diastole) (Diastolic pressure < 50 mmHg compromises perfusion of heart)
Kidneys
Low blood pressure a late sign of circulatory problems
Normal compensatory mechanisms maintain blood pressure initially
When these fail - pressure falls
Use blood pressure to calculate Mean Arterial
Pressure
S - D + D
3 MAP is average pressure for circulation Indicator of adequate tissue perfusion Normally 70 - 105; 90 average
Mean arterial pressure (MAP)
MAP < 60 mmHg inadequate Resistance = Pressure gradient /
Flow or re-arranged: MAP = C.0. x SVR
Two factors determine blood pressure
Cardiac output = stroke volume x heart rate
Systemic vascular resistance (SVR)
Stroke Volume (SV) determined by
Preload Contractility Afterload
Increased Preload Increases SV
Preload = filling volume of ventricles Increased blood volume stretches
muscle fibers Increases strength of contraction Requires longer time for ventricular
filling
Increased Contractility Increases SV
Contractility = force of muscle contraction
No change in muscle fiber length Increase force of contraction over
same time period Inotropic drugs
Decreased Afterload Increases SV
Afterload = resistance ventricles contract against
Primarily systemic vascular resistance
Systemic vasodilation reduces afterload
Factors afftecting Systemic Vascular Resistance
Radius of arterioles Blood volume Blood viscosity (Hematocrit)
Factors affecting Cardiac Output primarily affect systolic blood
pressure Ex. Exercise using large muscle mass
(legs) will require increase in cardiac output to supply more oxygen to working muscles
Will see an increase in systolic Diastolic will stay the same or
decrease since arteries of large muscle mass dilated
Factors affecting Systemic Vascular Resistance will primarily
affect diastolic pressure Ex. Exercise using small muscle
mass (arms) Vasoconstriction of large muscle
mass not being used Vasoconstriction increases
vascular resistance Diastolic will increase
Maximal Heart Rate correlates with Maximal O2 Consumption
HR max = 220 - age 75% HR max ------ 60 % VO2 max 80 ------- 70 90 ------- 82
Aerobic exercise 75 - 80% HR max
Heart Rate or Pulse - Evaluate for
Rate Rhythm Strength
Normal Heart Rate
60 - 100 Adults 90 - 120 Children 70 - 170 Newborns < normal = bradycardia > normal = tachycardia
Tachycardia
One of the cardinal signs of hypoxemia Increasing heart rate increases cardiac
output Increase oxygen delivery to tissues
Increasing HR increases C.O.
Until HR > 150 C.O. decreases due to inadequate
filling time
Rhythm
Regular or irregular Irregular beat may
indicate arrhythmias
Strength
Bounding?• Arteriosclerosis
Weak and thready? • shock
Pulsus Paradoxus Strength decreases with
spontaneous inhalation Increases with exhalation normal unless extreme Common in COPD Seen in 50% patients with
pericarditis
Pulsus Alterans
Alternating strong and weak pulses
May be sign of left ventricular failure
Not related to respiratory disease
Pulse Pressure
Systolic - Diastolic Normal 35 - 40 mmHg < 30 mmHg pulse hard to detect Decreasing pulse pressure early
sign of inadequate circulating blood volume
Can estimate systolic blood pressure if can palpate
Carotid pulse - then systolic is at least 60 mmHg
Femoral 70 mmHg Radial 80 mmHg
Pulse sites
Radial Brachial Carotid Femoral Dorsalis pedis
Check radial pulse before and after administering therapy
Aerosol medication may produce side-effects
First cardinal sign of hypoxemia is tachycardia
After taking pulse, continue palpating pulse as count respiratory rate
Assessment of Perfusion (microcirculation)
Peripheral skin temperature
• cold extremities indicate reduced perfusion
Urine Output
• one of the best indicators of C.O. and arterial pressure
• < 20 ml/ hr oliguria ( o lig uria)
Sensorium
• Brain sensitive to lack of oxygen and/or lack of glucose
• Both depend on blood supply to the brain - perfusion
• Confusion may signal inadequate perfusion or hypoxemia
Determine patient’s level of consciousness (LOC)
Oriented to person - know who they are
Oriented to place - know where they are
Oriented to time - know what today is, what year
Will typically see “Alert and oriented to PPT” in chart
Summary Patient assessment includes
evaluating patient’s cardiovascular system• Cardiac Output• BP/Pulse• Perfusion
Many of the therapeutic interventions of respiratory care will affect the cv system