Lab Quiz 1 Flashcards
How many of the ECG rhythms you are asked to look at on the simulator have the term
“Sinus” in them?
7
What formula do you use for counting HR?
1500/no. small boxes
How is the electricial acitivty of the heart conducted?
Through the SA node -> AV node -> bundle of HIS -> Purkinje Fibres
What are the segments and complexes of the Cardiac Cycle?
PR interval, PR Segment, QRS complex, ST segment and QR interval
What are the durations of key waves and intervals in normal adult heart at rest?
R-R interval = 1.00-0.60s
HR = 60/R-R
PR interval = 0.12-0.20s
QRS duration = <0.12s
QT interval = 0.36-0.44s
What is teh QT interval Formula?
K x (square root) of RxR interval
K = 0.37 men and 0.40 women
How is the P wave produced?
By atrial depolarisation
How is the QRS Complex produced?
by ventricular depolarisation atrial repolarisation also occurs, however its contribution is insignificant
How is the T wave produced?
by ventricular repolatisation
Which way do the leads provide views of electrical activity as it moves across the surface of the chest
from right to left
How do you calculate HR from 6 R waves
- no. of small boxes x 0.2 = y
2. (60s/y) X 5 =
How is the PR interval calculated
no. little boxes between P-QRS
E.g. y X 0.04 =
How do you calculate QRS duration?
y X 0.04 = 0.08s
What is meant by “normal sinus rhythm”?
NSR means the rhythm that originates from the sinus node and describes characteristics of a healthy person
What is Bradycardia
When the HR is <60
What is Tachycardia
When the HR is >100
If the PR interval was lengthened this would indicate
delayed conduction of SA node - 1st degree heart block
If the QRS duration was lengthened this woud indicate
prolonged ventricular repolarisation
Why might you be concerned if someone has a long QT interval?
Fast heart beats can cause fainting and some people with the condition can have seizures. Long QT interval can cause sudden death
In a deep breathing trace if the rhythm irregular in resting condition but in the ECG is otherwise normal - this is?
Arial fibrillation
Considering the front views with the 6 transverse views - an inferior view of the heart?
2, 3, aVF
Considering the front views with the 6 transverse views - a left lateral view of the heart?
5, 6, aVL
Considering the front views with the 6 transverse views - an anterior view of the heart?
1, 2, 3, 4
What is the MEA?
Mean electrical Axis
gives an appropriate position of the heart estimated directly using 2 ECG leads that are perpendicular to one another
What is the angle and lead MEA uses
60 degrees and lead II view
What is the axis in MEA set by
The axis is set by the
direction of the mean electrical impulse as the wave of depolarization travels from the AV node
through the ventricular myocardium.
What happens after a myocardial infarction to the heart tissue
after a myocardial infarction, tissue that has died will not contribute to the ECG and
therefore disrupts the mean electrical axis causing a left or right axis shift - helps determine the extent of ischaemic damage
What is the determination of Left Ventricular Hypertrophy
LVH results in increased R wave amplitude in the left-sided ECG leads and
increased S wave depth in the right-sided leads. The thickened LV wall leads to
prolonged depolarisation (increased R wave peak time) and delayed repolarisation (ST and T-wave
abnormalities) in the lateral leads.
What is Systolic pressure defined as
‘Systolic pressure’ is defined as the peak pressure reached during the cardiac cycle. The period during
the relaxation of the ventricles is called ‘diastole’
What is the diastolic pressure defined as
The value when the arterial blood pressure is at its lowest —
immediately before the contracting ventricle pushes blood into the arteries again—is called the
‘diastolic pressure’
What are the Blood pressure values for adults
<120/<80 = optimal
120-129/80-84 = Normal
130-139/85-89 = high normal
140-159/90-99 = Grade 1 hypertension
160-179/100-109 = Grade 2 hypertension
> 180/>110 = Grade 3 Hypertension
> 140/<90 = isolated systolic hypertension
What is RPP
Estimated rate pressure product
- its clinical utility is its a reliable indicator of myocardial oxygen demand
The correct pressure for initial cuff inflation
160
clincially 200
The correct rate of cuff deflation
2-3 mmHg/sec
Minimum interval between successive measurements
1 minute
Why do clinicians sometimes measure blood pressure
a) in both arms?
If measurements differ more than 10 mmHg could be warning sign of cardiovascular disease
Why do clinicians sometimes measure blood pressure in different postures
Orthostatic hypotension - drop in BP when sitting to standing
How is mean arterial blood pressure MAP measured
DBP + (SBP-DBP/3)
How do you calculate estimate rate pressure product
HR x SBP
What happens if you take a beta blocker
SLow HR and low BP
y. Spontaneous breathing is controlled by the respiratory complex in the medulla/pons
of the brain
y. Spontaneous breathing is controlled by the respiratory complex in the medulla/pons
of the brain
The respiratory complex ensures that gaseous exchange at the lung matches the
requirements of the body. In times of increased demand, the rate and depth of breathing are
increased to bring more fresh air into the lungs. The respiratory complex is stimulated by central
chemoreceptors also located in the medulla/pons that are sensitive to the partial pressure of carbon
dioxide (PCO2) in the blood acting via pH changes of the cerebrospinal fluid.
The respiratory complex ensures that gaseous exchange at the lung matches the
requirements of the body. In times of increased demand, the rate and depth of breathing are
increased to bring more fresh air into the lungs. The respiratory complex is stimulated by central
chemoreceptors also located in the medulla/pons that are sensitive to the partial pressure of carbon
dioxide (PCO2) in the blood acting via pH changes of the cerebrospinal fluid.
Quiet and maximal breathing enables the measurement of 3 discrete volumes:
VT = Tidal Volume IRV = Inspiratory Reserve Volume ERV = Expiratory Reserve Volume
Note that a 4th volume, RV = Residual Volume, the volume of air remaining in the lungs after a full
expiration, cannot be measured by spirometry as individuals are unable to empty their lungs
completely due to the rigidity of the thorax.
Note that a 4th volume, RV = Residual Volume, the volume of air remaining in the lungs after a full
expiration, cannot be measured by spirometry as individuals are unable to empty their lungs
completely due to the rigidity of the thorax.
Clinically, it is usual to report these as combinations of volumes since this provides a better idea of
how much air is in the lungs at different points of the respiratory cycle (quiet and maximal). These
combined volumes are called capacities:
EC = Expiratory Capacity FRC = Functional Residual Capacity TLC = Total Lung Capacity VC = Vital Capacity IC = Inspiratory Capacity
During a single breath (in and out), a specific volume of air is drawn into and then expired from the
lungs; this is Tidal Volume (VT). Over a one minute period a number of such breaths occur; this is
the respiratory frequency (fR)
During a single breath (in and out), a specific volume of air is drawn into and then expired from the
lungs; this is Tidal Volume (VT). Over a one minute period a number of such breaths occur; this is
the respiratory frequency (fR)
The product of ƒR and VT is the amount of air exhaled in one minute of breathing (V̇ E) – the correct
term for this is Pulmonary (or Minute) Ventilation. This parameter changes as fR or VT (or both)
changes – e.g. with physical activity.
The product of ƒR and VT is the amount of air exhaled in one minute of breathing (V̇ E) – the correct
term for this is Pulmonary (or Minute) Ventilation. This parameter changes as fR or VT (or both)
changes – e.g. with physical activity.
VA =
VA = FR (VT - VD)
VD = dead space volume
VD = (weight x 2.2) + 30 mL
Estimated PaCO2 = ?
VCO2 = 2.8 x weight = mL/min
Therefore,
PaCO2 = VCO2 x (0.863/VA)
Explain in principle how the %ref value on the Medikro print-out is determined
height, weight, ethnicity
What differences (if any) would you expect in the following lung function measures of an individual with (a) an obstructive condition (eg COPD) (b) a restrictive condition (Pulmonary Fibrosis), compared to a healthy person with the same physical characteristics.
Obstructive FRC - up RV - up FVC - same TLC - up
Restricitive FRC - down RV - down RVC - down TLC - down
