Cardiovascular Assessment II Yuriy Slyvka MD, PhD

Cardiovascular Assessment u Cardiac Output Blood Pressure – Systolic / Diastolic Pulse u Perfusion

Blood Pressure u Systolic - Normal mmHg u Diastolic - Normal mmHg u Children vary with age u Neonate over mmHg

Systolic u Maximum pressure exerted on arterial wall during ventricular contraction

Diastolic u Pressure in vasculature during ventricular relaxation

Indirect Blood Pressure Measurement via Cuff u Wrap blood pressure cuff around upper arm u Auscultate over artery in antecubital fossa u Inflate cuff rapidly u Deflate cuff slowly while listening

Mechanism u Cuff inflated - occludes artery - no sound u Slowly deflate cuff - first sound = systolic u Continue to deflate cuff until sound disappears = diastolic u Tapping sounds heard with each heart beat called Korotkoff’s sounds (Ko rot kof)

Technique u Usually use non-dominant arm u Inflate to approx 160 mmHg u Drop pressure approximately 3 mmHg/sec u Standard adult cuff 5 inches wide u Pediatric 3 inches wide

Sources of Error Resulting in High BP Measurements u Cuff too narrow Width of cuff approx 40% circumference of arm u Applied too tight or too loose u Excessive cuff pressure should start 30 mmHg above systolic u Pressing stethoscope too tightly over artery will affect diastolic pressure

Hypertension u BP persistently > / 90 u Secondary means cause is known May be a side-effect of medication u Primary Hypertension means cause is unknown

Hypotension u BP < 95 / 60 u Late sign of hypovolemia, cardiac failure, shock u 90 / 60 not uncommon in young females

Low blood pressure results in inadequate perfusion u Brain u Heart - (70 % coronary artery perfusion occurs during diastole) (Diastolic pressure < 50 mmHg compromises perfusion of heart) u Kidneys

Low blood pressure a late sign of circulatory problems u Normal compensatory mechanisms maintain blood pressure initially u When these fail - pressure falls

Use blood pressure to calculate Mean Arterial Pressure u S - D + D 3 u MAP is average pressure for circulation u Indicator of adequate tissue perfusion u Normally ; 90 average

Mean arterial pressure (MAP) u MAP < 60 mmHg inadequate u Resistance = Pressure gradient / Flow u or re-arranged: MAP = C.0. x SVR

Two factors determine blood pressure u Cardiac output = stroke volume x heart rate u Systemic vascular resistance (SVR)

Stroke Volume (SV) determined by u Preload u Contractility u Afterload

Increased Preload Increases SV u Preload = filling volume of ventricles u Increased blood volume stretches muscle fibers u Increases strength of contraction u Requires longer time for ventricular filling

Increased Contractility Increases SV u Contractility = force of muscle contraction u No change in muscle fiber length u Increase force of contraction over same time period u Inotropic drugs

Decreased Afterload Increases SV u Afterload = resistance ventricles contract against u Primarily systemic vascular resistance u Systemic vasodilation reduces afterload

Factors afftecting Systemic Vascular Resistance u Radius of arterioles u Blood volume u Blood viscosity (Hematocrit)

Factors affecting Cardiac Output primarily affect systolic blood pressure u Ex. Exercise using large muscle mass (legs) will require increase in cardiac output to supply more oxygen to working muscles u Will see an increase in systolic u Diastolic will stay the same or decrease since arteries of large muscle mass dilated

Factors affecting Systemic Vascular Resistance will primarily affect diastolic pressure u Ex. Exercise using small muscle mass (arms) u Vasoconstriction of large muscle mass not being used u Vasoconstriction increases vascular resistance u Diastolic will increase

Maximal Heart Rate correlates with Maximal O2 Consumption u HR max = age u 75 % HR max % VO2 max u u u Aerobic exercise % HR max

Heart Rate or Pulse - Evaluate for u Rate u Rhythm u Strength

Normal Heart Rate u Adults u Children u Newborns u < normal = bradycardia u > normal = tachycardia

Tachycardia u One of the cardinal signs of hypoxemia u Increasing heart rate increases cardiac output u Increase oxygen delivery to tissues

Increasing HR increases C.O. u Until HR > 150 u C.O. decreases due to inadequate filling time

Rhythm u Regular or irregular u Irregular beat may indicate arrhythmias

Strength u Bounding? Arteriosclerosis u Weak and thready? shock

Pulsus Paradoxus u Strength decreases with spontaneous inhalation u Increases with exhalation u normal unless extreme u Common in COPD u Seen in 50% patients with pericarditis

Pulsus Alterans u Alternating strong and weak pulses u May be sign of left ventricular failure u Not related to respiratory disease

Pulse Pressure u Systolic - Diastolic u Normal mmHg u < 30 mmHg pulse hard to detect u Decreasing pulse pressure early sign of inadequate circulating blood volume

Can estimate systolic blood pressure if can palpate u Carotid pulse - then systolic is at least 60 mmHg u Femoral 70 mmHg u Radial 80 mmHg

Pulse sites u Radial u Brachial u Carotid u Femoral u Dorsalis pedis

Check radial pulse before and after administering therapy u Aerosol medication may produce side-effects u First cardinal sign of hypoxemia is tachycardia u After taking pulse, continue palpating pulse as count respiratory rate

Assessment of Perfusion (microcirculation) u Peripheral skin temperature cold extremities indicate reduced perfusion u Urine Output one of the best indicators of C.O. and arterial pressure < 20 ml/ hr oliguria ( o lig uria)

u 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) u Oriented to person - know who they are u Oriented to place - know where they are u Oriented to time - know what today is, what year u Will typically see “Alert and oriented to PPT” in chart

Summary u Patient assessment includes evaluating patient’s cardiovascular system Cardiac Output BP/Pulse Perfusion u Many of the therapeutic interventions of respiratory care will affect the cv system