A + P Cardiorespiratory Lab

Question 1

how does electrical current flow between the electrodes dictate the recorded ECG deflections shown in the wave form

Answer 1

when depolarization flows toward a + electrode within a “recording lead” you should see a positive (upward) deflection on the ECG paper (leads I, II, and III)
when depolarization flows toward a - electrode you should see a negative (downward) deflection (aVR or aVL)

Question 2

what does the P-R interval represent

Answer 2

conduction through the AV node

Question 3

how long should the P-R interval be?

what if it is too short or too long?

Answer 3

normal: 120-200 ms
too long: probable first degree heart block
too short: possible pre-excitation (presence of an accessory pathway between the atria and ventricles) or AV nodal (junctional rhythm)

Question 4

what does the QRS interval represent

Answer 4

indicates the origin of each QRS complex (e.g. sinus, atrial, or ventricular)

Question 5

normal QRS
short
long

Answer 5

normal: 70-100 ms

short (100 ms): ventricular origin or bundle branch block

Question 6

what does the S-T segment represent

indications if it is above or below the “baseline” of the ECG waveform

Answer 6

the interval between ventricular depolarization and repolarization
indications
-myocardial ischemia/infarction

Question 7

what does QT represent

Answer 7

time taken for both ventricular depolarization and repolarization

Question 8

normal QT interval
long
short

Answer 8

350-450 ms (normal usually less than 1/2 the RR interval)

long: increased risk of ventricular arrhythmia or myocardial infarction
short: increased risk of paroxysmal atrial and ventricular fibrillation or sudden cardiac

Question 9

SBP

• represents
• normal values

Answer 9

represents the pressure exerted by blood against the arterial walls during systole (ventricular contraction)
normal is 115-120 mmHg

Question 10

DBP

• represents
• normal values

Answer 10

represents the pressure exerted by blood against the arterial walls during diastole (ventricular relaxation)
normal is 75-80 mmHg

Question 11

what can a high SBP and DBP indicate

Answer 11

the vessels have become hardened and/or occluded by plaque buildup (atherosclerosis) and cannot respond to fluctuation in pressure incurred during heart contractions

Question 12

results of high and low FVS

Answer 12

less
-could have small lungs for stature, 
-really deconditioned
-smoker
-might have a restrictive lung disease
greater
-big lungs for stature
-good cardiovascular shape
-play a wind instrument

Question 13

results of high and low FEV1.0

Answer 13

less
-means you could have an obstructive lung disease
greater - could be in great shape to play a wind instrument

Question 14

obstructive lung disease effect on FVC, FEV1.0, and FEV1.0/FVC

Answer 14

FVC
-no or little change
FEV1.0
-reduced score
FEV1.0/FVC - reduced score

Question 15

restrictive lung disease effect on FVC, FEV1.0, and FEV1.0/FVC

Answer 15

FVC: reduces score
FEV1.0: reduced score
FEV1.0/C - no or little change