Lab Exam 2- Lab 8 Flashcards
what is the best overall indicator of cardiorespiratory function
VO2 max
what provides a more sensitive measurement of changes in cardiorespiratory function
cardiac and hemodynamic assessments (BP)
common measurements for all GXT procedures include
cardiac electrical conduction through 12 lead ECGs
RPE
O2 consumption
BP
what is one of the most valuable and convenient indicators of CV health
BP
how many americans have high blood pressure
one third of Americans have hypertension which can be present without symptoms
blood pressure is recorded as
a ratio of systolic pressure/diastolic pressure
BP= sBP/dBP
systolic blood pressure
the pressure in the arteries when the heart contracts
diastolic pressure
the pressure in the arteries when the heart is filling in between beats
pulse pressure (PP)
the difference between diastolic and systolic pressures
PP= sBP-dBP
healthy blood pressure is defined as
less than 120/80 mmHg
as we age what happens to blood pressure
BP rises steadily with age due to arterial stiffness and plaque buildup
mean arterial pressure (MAP)
the average pressure in the arteries during a cardiac cycle
importance of MAP
determines the rate of blood flow through vasculature
how to calculate MAP at rest
1/3 PP + dBP
why is MAP calculated the way it is
because the heart is in diastole (relaxation) for 2/3 of the cardiac cycle AT REST** meaning it is not accurate during exercise because the heart is in SYSTOLE the majority of the time compared to rest
how is MAP determined centrally
by cardiac output (Q)
how is MAP calculated peripherally
via TPR or total peripheral resistance
MAP = Q*TPR
TPR
the sum of the resistance of blood flow in the vasculature
blood pressure is influenced by
anything that influences Q and TPR and increasing ANY of these variables will increase BP
why does BP increase during exercise
due to a large increase in Q
how does Q increase during exercise
elevated HR and LVR contractility as a result of SNS + increased venous return (preload)
MAP refers to
afterload and is a barrier to the ejection of blood from the ventricles
if you have a higher afterload what happens to SV
increases because SV must increase more than BP to pump blood to the body
what helps reduce the effects of increased afterload after exercise
vasodilation of the arterioles supplying the blood to the active muscles
net effect of exercise on BP
increase in systolic BP due to increased Q and no change in dBP due to vasodilation
aerobic exercise training effects on BP
decreases resting and submaximal exercise BP and decreases TPR (vascular tone)
what happens to BP at maximal exercise
dBP changes
sBP and MAP do not change
does weight loss have favorable or unfavorable influences on BP
favorable
benefits of performing GXT
powerful predictive and diagnostic capabilities
useful for testing different things in different individuals
extending medical history and physical
evaluating exertional discomfort
evaluating hidden CHD
identifying risk in patients with known CVD
Rx exercise
prior to GXT subjects are classified into 3 risk categories based on
age
known disease
risk factors
categories are low, medium, and high
when can the GXT be stopped
at a predetermined point (%HRmax) or point of volitional exhaustion
chest pain/breathlessness
relative criteria for stopping GXT
subjects discretion
absolute criteria for stopping GXT
always stopped
ECG and BP abnormalities during an exercise test may be indicative of or predictive of
CAD and suggest need for further testing
changes in cardiac function during GXT
linear increase in HR to max
linear increase in SV until a certain intensity
when does SV plateau in untrained individuals
approx 50%
when does SV plateau in trained individuals
at higher than 50% intensities and may not ever plateau in elite athletes
what happens to Q during GXT
Q increases greatly at first and less as SV plateaus
ECG
electrocardiogram
an indicator of the hearts ability to function normally under increased myocardial O2 demand
what is normal and can be seen in reduced RR intervals and minor QRS complex and P wave changes
altered AP duration, conduction velocity and contractile velocity associated with an increase in HR during exercise
arrhythmias not present at rest can be present during
execise as conduction disturbances and myocardial ischemia (reduced blood flow)
most common sign of myocardial ischemia during GXT is
ST segment depression
central feature of GXT is
functional exercise capacity since VO2 is the best predictor of CV function
prognostic capabilities of GXT are defined by normal and abnormal cardiac and hemodynamic changes . what is considered normal
achieve >80% predicted HRR
sBP increases 5 mmHg per MET
HRrecovery decreases 12 bpm in 1 minute
3 min post exercise sBP <90%max sBP
normal cardiac rythyms
prognostic capabilities of GXT are defined by normal and abnormal cardiac and hemodynamic changes . what is considered abnormal
achieve <80% predicted HRR
slow increase or sudden decrease in sBP
sBP >250 mmHg or increases >140 mmHg from rest
dBP increases more than 10mmHg
dysrhythmias, ST segment depression or elevation
BP measurement positions
one standing and one sitting
how to measure BP
seated position wrap cuff over brachial artery
inflate cuff to no more than 200 mmHg
slowly release until you hear Kortokoff sound (sBP)
continue releasing until sound disappears (dBP)
