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