PDF focus Flashcards
What is the pathway through the heart?
SA node
Internodal tracts
AV node
bundle of His
Bundle Branches
Purkinje fibers
What are the three internodal tracts?
1.Anterior (Left) Bachmann bundle
- Middle - Wenckebach
- Posterior - Thorel
What are the three conduction velocities?
- SA + AV - 0.02 (Slow conduction)
- HIS, Branches, Purkinjie - 1.0 (Fast)
- Myocardium - 0.1 (Intermediate)
What is conduction velocity a function of?
- RMP
- Amplitude of action potential
- Rate of change in phase 0
What five things affect conduction velocity?
ANS tone
Hyperkalemia
Ischemia
Acidosis
Antiarrhythmic drugs
What are the accessory pathways?
Bypasses normal conduction pathway
What is the James fiber pathway?
Atrium to the AV node
What is the atrio-Hisian fiber?
Atrium to HIS bundle
What is Kents bundle?
Atrium to ventricle
What is Mahaims bundle?
AV node to ventricle
What happens during phase 0 of ventricular action potential? Ion Movement?
Depolarization (QRS)
Na+ rushes into cell - making it more positive
What happens during phase 1 of ventricular action potential? Ion Movement?
Initial repolarization (QRS)
Cl- moves in and K+ moves out
(downward deflection since it is becoming more negative inside the cell)
What happens during phase 2 of ventricular action potential? Ion Movement?
Plateau phase (QT interval)
Ca + in and K+ out
Balance each other out so it is a straight line
What happens during phase 03 of ventricular action potential? Ion Movement?
Final repolarization (T wave)
K+ out
What happens during phase 4 of ventricular action potential? Ion Movement?
Resting phase (T wave to QRS)
Na+ out
When is the absolute refractory period?
Between phase 0/1 and ends in the middle of phase 3
NOTHING can stimulate the cell
When is the relative refractory period?
Middle of phase 3
VERY STRONG stimulus is required
What can be seen with PR depression?
Pericarditis
What condition is associated with a U wave?
Hypokalemia
Peaked T waves can be caused by?
MI, Hyperkalemia, Intracranial bleed
ST elevation or depression greater than____mm, can be an MI?
1mm
Hypercalcemia and hypocalcemia what is seen on EKG?
Hyper - Shorted QT
Hypo - Long QT
Which limb leads monitor the inferior wall of the heart?
II, III, aVF
Which limb leads monitor the later side of the heart?
I, aVL, V5, V6
Which limb leads monitor the LAD septum?
V1, V2
Which limb leads monitor the LAD anterior?
V3, V4
What is the normal axis degree numbers?
Between -30 and +90
If the axis is more negative, that means what type of deviation?
Left
If the axis is more positive, that means what type of deviation?
Right
What two things can cause a Sinus arrythmia?
-Breathing
–Inhale faster HR
–Exhale slower HR
-Bainbridge reflex
What is the first line of treatment for bradycardia? Dosage?
Atropine but if less than 0.5 can cause paradoxical bradycardia through the muscarinic receptors
What should severely symptomatic bradycardic patients receive?
Pacing
How does glucagon work?
Increasing cAMP
Helpful in CCB and BB overdose
How does sinus tachycardia affect the heart?
Increases O2 consumption while decreasing supply
What must be performed with new AFIB or Aflutter older than 48 hours?
TEE
Should you cancel surgery with new AFIB or Aflutter?
Yes
What is the most common postoperative tachyarrhythmias?
AFIB
Is afib or aflutter organized?
Aflutter with a rate of 250-300
Not all signals get past the AV node
Treatment for Aflutter?
Cardioversion at 50 J
Where do PVC originate from? What causes them?
AV node
Many things -
When and how should PVCs be treated?
When they are frequent (>6 a minute)
-Reverse the underlying cause
-Treat with lidocaine 1mg/kg
What is Brugada syndrome
Sodium channel issue
Causes nocturnal death in Asian men
Can be seen on V1-V3 and need ICD
What heart blocks affect the AV node? treatment?
Type 1
Type 2 I (longer longer, drop)
Monitor
What heart block affects the bundle branches?
Type 2 II (random p drops)
What heart block has degeneration of the atrial conduction system? (Lenegre’s)
Type 3
Need to pace or isoproterenol
How does adenosine work? Half life?
Slows conduction through the AV node by stimulating the adenosine receptor and inhibits K channels
Hyperpolarizes the membrane
5 second half life
When is adenosine helpful? Not?
What can it cause?
Good for SVT and WPW
Bad for afib, aflutter, vtach
Bronchospasm in asthmatic patients
Dosage for adenosine for peripheral and central?
P -6mg then 12
C-3mg then 6
What is the most common cause of tachyarrhythmias?
Reentry pathways
(backwards movement of electrical impulse)
How to stop a reentry pathway?
Break the circuit
1. Slow conduction velocity
2. Increase refractory period
Examples of a reentry pathway where velocity is too slow?
Ischemia
Hyperkalemia
Examples of a reentry pathway where refractory period is shorter?
Epi
Electric shock
Examples of a reentry pathway where it occurs over a long distance?
Left atrial dilation to mitral stenosis
What is WPW?
Most common pre-excitement syndrome
Direct communication between atria and ventricle
Seen with Delta wave
What are two ways WPW can be classified ? Which is most common? What is more dangerous?
Orthodromic and antidromic
Common-Orthodromic
Dangerous - Antidromic
Which AVRNT has a narrow QRS and a wide QRS?
Ortho- Narrow
Anti- Wide
What are two safe options for both AVRNT?
Amio and cardioversion
What are the only three things for antidromic treatment?
Amio
Cardioversion
-Procainamide
What is the treatment for WPW combined with afib?
Procainamide
Definitive treatment for WPW? What must be monitored?
Ablation
Esophageal temp
Treatment for torsades?
Mag
Pacing
Avoid SNS stimulation
What does DDD mean on a pacemaker?
Dual Paced
Dual Sensed
Dual triggered and inhibited
What does AOO mean on a paceaker?
Atrial paced
No sense
No response to native cardiac activity
What does VVI mean on a pacemaker?
Ventricular paced
Ventricular sensed
I tells pacemaker not to fire if electrical activity is seen
What 3 things cause a pacemaker to fail?
- Pulse generator failure
- Lead failure
- Failure to capture
What can impair a pacemaker?
Electrocautery and radiofrequency ablation
Bipolar is much better
MRI with a pacemaker?
Contradicted
What is the most important thing to know about pacemakers?
The underlying rhythm so you know how to treat
What happens when a magnet is placed on a pacemaker?
Goes to asynchronous mode
What happens when a magnet is placed on a ICD?
Suspends the shock
What happens when a magnet is placed on a pacemaker and ICD?
Suspends ICD but not the pacemaker
What is seen after a PAC?
Non compensatory pause
In Aflutter, does every atrial depolarization have a contraction?
Yes
What two syndromes are associated with prolonged QT?
Timothy and Romano Ward
What does cerebral oximetry monitor?
Global oxygenation of VENOUS blood.
75% of blood in the brain is venous
What percentage change suggests a reduction in cerebral oxygenation? What can contaminate the signal
> 25%
Scalp hypoxia can throw off numbers
How do brain waves change during anesthesia?
Induction and light anesthesia increases beta waves
What produces burst suppression?
Deep anesthesia
At what MAC level can cause complete suppression of Isoelectricity?
1.5-2.0
Which anesthetic gas can produce beta waves?
N2O
Which anesthetic gas can produce seizures?
Sevo
Which drug can cause myoclonus but not associated with epilepsy
Etomidate
Which drug can falsely elevate EEG?
Ketamine
When else can burst suppression occur?
Hypothermia, CPB
What is unilateral burst suppression suggestive of?
Cerebral ischemia
What are the order of brain waves?
Beta
Alpha
Theta
Delta
Burst suppression
Isoelectricity
Which brain wave is associated with GA, hypothermia, CPB, and ischemia?
Burst suppression
Which brain wave is associated with GA and children sleep?
Theta
Which brain wave is associated with GA, deep sleep, and brain injury?
Delta
Which brain wave is associated with awake mental stimulation and light anesthesia?
Beta
Which brain wave is associated with awake but restful sleep with eyes closed?
Alpha
When happens to brain waves as the anesthesia becomes deeper?
Lower frequency and higher amplitude
What two things can interfere with BIS?
Nitrous and Ketamine
What is the time delay of BIS?
20 seconds
When also is BIS less accurate?
Children, hypothermia, increased muscle tone, encephalopathy
Which law does electricity follow ?
Ohm’s law
Voltage - driving pressure
Current - Flow
Impedance - Resistance
What is the maximum allowable current leak in the OR? When does Vfib occur?
10 uA
100 uA
Is the OR power supply grounded?
NO
Is the equipment in the OR grounded?
YES
What is the Line isolation monitor?
It tells you when the OR BECOMES GROUNDED
Does the Line isolation monitor protect you?
No it is just alarm when a leak of 2-5 mA is detected
What is a grounding pad?
Provides an exit point for electricity on the patient.
IT DOES NOT GROUND THE PATIENT
What do you do if there is exhaustion of the CO2 absorbent?
Increases FGF to 5-8
TIVA
Do not increase the MV because it will not fix the issue
If increasing FGF does not fix the problem, what is likely the issue?
Incompetent unidirectional valve
What components are not present in a Mapleson circuit?
Unidirectional valves
CO2 absorber
Advantages of a Mapleson?
Less airway resistance (good for peds)
Convenient
Easily scavenged
Bain circuit prevents heat loss
What is the pethick test?
A test for the integrity if the inner tubing on the Bain circuit
Which Mapleson is best for spontaneous ? Worst?
Best - A (spontAneous)
Worst - B
Which Mapleson is best for cmv ? Worst?
Best- D (controlleD)
Worst - A
How much FGF is required when using a Mapleson?
2.5 x minute ventilation
Mapleson A needs 20L/min
What is the Bain system good for?
Modified Mapleson D
Has thin inner tubing and the gas is warmed through the corrugated tubing around it
How is the Pethick test performed?
-Occlude the elbow
-Close APL
-Flush with O2
-Remove occlusion while flushing
**if the bag deflates it is okay to use
***if the bag stays inflated, NOT okay
Which Mapleson circuits are most likely to be seen today?
D,E,F
How is compiance measured?
Change in Volume / Change in Pressure
What is compliance influenced by?
Muscle tone
Degree of lung inflation
Alveolar surface tension
Interstitial lung water
Pulmonary fibrosis
What is dynamic compliance?
Movement of lungs
What is static compliance ?
Lungs are not moving
When is plateau pressure measured?
-During static (no airflow)
-Barotrauma when pressure exceeds 35
What is a normal Alpha angle? What conditions cause in increase?
100-110 degrees
**obstruction
COPD, Kink, bronchospasm
What may be the cause of increased beta angle?
Falty unidirectional valve
What is the PaO2 if the SpO2 reads 90?
60 - 30 point difference
What site is the fastest response for a SpO2? Slowest?
Fastest - Head
Middle - Finger
Slowest-Toe
Inline(Main stream) end tidal is useful for ?
Fast response
Increases Dead space
Doesn’t require a pump or trap
Side stream (diverting) is useful when?
Outside the airway
Requires pump/water trap
Slower response time
What two wavelengths does a pulse emit?
940 - near infrared(arterial,oxy)
660- Red light (Venous,deoxy)
What shifts to L on the oxyhemoglobin curve?
Decreased everything and alkalosis
What shifts to R on the oxyhemoglobin curve?
Increased everything and acidosis
What does the pulse ox monitor ? (3 things)
What does it not?
- Hgb saturation
- HR
- Fluid responsiveness
**Does not measure anemia or ventilation
What is methemoglobin?
Equal light at 660 and 940
Pulse ox will read 85%
Could be higher or lower
What is carboxyhemoglobin?
Absorbs at 660
So it overestimates SpO2
May say 99% when it really is 80%
Which factors do not affect pulse ox?
Hgb S
Hgb F
Jaundice
Fluorescein
Polycythemia
Acrylic nails
How is all gas analyzed on all modern machines?
Infrared spectrophotometry
O2 is by galvanic cell or paramagnetic
What is the ideal length of the bladder on a BP cuff?
80% circumference
What is the ideal width of the bladder on a BP cuff?
40%
Where is the narrowest PP?
At the artic root
SBP is lowest and DBP is highest
Where is the widest PPV?
Foot
If the BP cuff is above the heart will the reading by falsely high or low?
Falsely low
How much does BP change for every 10cm? every inch?
10cm = 7.4mmhg
1inch= 2mmhg
How many oscillations are appropriate for an optimally damped Art line?
1
How many oscillations are seen for an under damped Art line?
many bounces
SBP is overestimated and DBP is under
How many oscillations are seen for a over damped Art line?
None
SBP is underestimated, DBP is over
Examples of an overdamped Art line?
Air bubble
Clot
No pressure
Examples of under dampened Art Line?
Stiff tubing
Catheter whip
Is the MAP accurate with an over or under dampened art line?
Yes
Distance from insertion site for
Subclavian
R IJ
L IJ
Femoral
Basilic
Subclavian - 10 cm
R IJ - 15 cm
Left IJ - 20 cm
Femoral - 40 cm
Basilic - 45
Distance through heart?
RA
RV
PA
PAOP
RA 0-10cm
RV 10-15cm
PA 15-30cm
PAOP 25-25cm
Where should a CVP catheter reside? PA catheter?
CVP - Junction of the vena cava and RA (**NOT INSIDE)
RA - in the PA
When does infection risk increase for central lines?
After three days
What is at risk for obtaining an L IJ?
Thoracic duct puncture resulting in chylothorax
Should you advance a PA if the patient has a LBBB?
NO, advancing may result in a RBBB which leads to complete heart block
Classic sign of a pulmonary artery rupture?
Hemoptysis
What three things increases risk of a PA rupture?
-Hypothermia
-Anticoagulation
-Advanced age
What is the a wave on a CVP?
Right atrial contraction
(Just after the P wave on an EKG)
What is the C wave on a CVP?
Right ventricle contraction (the bulging of the tricuspid into the TA)
Just after the QRS on an EKG
What is the X descent on a CVP?
RA relaxation
ST segment on EKG
What is the V wave on the CVP?
Passive RA filling
Just after the T wave begins on a EKG
What is the y descent on an CVP?
RA empties through a open tricuspid valve
After the T wave ends
What should Right atrial pressure equal?
Left ventricle end diastolic pressure
What might it mean if the A wave is loss on a CVP?
Atrial contraction is lost
Afib
V pacing
What might a large A wave mean?
High pressure or resistance
Lung disease
Diastolic dysfunction
Tricuspid stenosis
MI
AV issues
What might a large V wave signal?
-Tricuspid regurg
-Acute Increase in intravascular volume
-RV papillary ischemia
Normal RA pressure?
1-10
Normal Right ventricle pressure?
15-30
and
0-8
*Diastolic is equal to cvp
Normal PA pressure? Waveform?
25/10
Waveform looks just like A line
Normal PAOP? Waveform?
5-15
Just like a CVP waveform
What zone should the PAC be in?
Zone III since there is a continuous column of blood
Zone III is the dependent region
Pa>Pv>PA
How can you tell the PA tip is NOT in west zone III?
- Nonphasic tracing
- PAOP > PA end diastolic rescuer
- Cannot aspirate blood from the distal port
Conditions where PAOP underestimates LVEDV?
Aortic regurg
How is thermodilution done?
5% dextrose and NS are injected through the proximal port.
If the fluid rapidly travels then the CO is high and if it takes longer then the CO is low
What are the 4 variables to Mixed venous saturation?
Q=CO
VO2=O2 consumption
Hgb
SaO2
Why is a PA required to measure SvO2?
Need to measure all blood returning to the heart
SVC
IVC
Coronary Sinus
Distance for R subclavian, R IJ, L IJ?
Distance for PA through heart?
R sub - 10cm
R IJ - 15cm
L IJ - 20
RA - 10
RV - 15
PA - 20
Wedge - 30
When should CVP be measured?
End expiration
What is seen on the PA waveform when the PA enters the PA?
Diacrotic notch
Increased in diastolic BP
When does PAOP overestimate LVEDP?
PEEP and diastolic dysfunction
When does PAOP underestimate LVEDP?
Aortic insufficiency
How does a high injectate volume effect CO? Low volume?
High volume = underestimates
Low volume = overestimates
Can you accurately measure CO with a R to L shunt?
No
How does warm injectate and a partially wedged catheter effect CO?
over estimates
When should thermodilution be used over continuous CO? Why?
Unstable patients because continuous monitoring has a delay
How does hypothermia effect SVO2?
Increases SvO2
How does fever effect SVO2?
Decreases
How does cyanide toxicity effect SVO2?
Increases
How does anemia effect SVO2?
Decrease
How does RBC infusion effect SVO2?
Increases
How does shivering and pain effect SVO2?
Decreases
How does hypoxemia effect SVO2?
Decreases
How does thyroid storm effect SVO2?
Decreases
How does increased CO effect SVO2?
Increases
What is a normal SVO2?
65-75%
When assessing fluid responsiveness, how much should stroke volume increase when a 250mL bolus is given ?
10%
How does increased LV filling effect stroke volume? Decreased filling?
Increased filling = larger stroke volume (Starling mechanism)
Decreased filling = Smaller stroke volume
Howd does a positive pressure breath effect LV filling?
Augments LV filling, Decreases RV filling
Should you use an esophageal doppler with esophageal disease? Will it effect the values?
Do not use but won’t effect the value if used
What varibles will affect esophageal doppler?
Any issues with the aorta, pregnancy, CPB
An esophageal doppler, when medicine is given to increase the width of the triangle?
Fluid, by giving fluid the it will become wider
An esophageal doppler, when medicine is given to increase the height of the triangle?
Vasodilator
An esophageal doppler, when medicine is given to increase the height and decrease the width of the triangle?
Inotrope
What conditions increased pulmonary resistance?
kinked tube
ET cuff herniation
Foreign body
Compression of airway
bronchospasm
bronchial secretions