Equipment & Monitoring Flashcards
What components are present in the high pressure system of the AGM? What is the gas pressure?
-Hanger Yoke
-Yoke block w/check valves
-Cylinder Pressure Gauge
-Cylinder pressure regulators
Gas pressure = cylinder pressure
What components are present in the intermediate pressure system of the AGM? What is the gas pressure?
-Pipeline inlets
-Pressure gauges
-Ventilator power inlet
-Oxygen pressure failure system
-Oxygen second-stage regulator
-Oxygen flush valve
-Flowmeter valve
Gas pressure = 50 PSI (pipeline) and 45 PSI (cylinder)
What are the components of the low pressure system?
Flowmeters
Vaporizers
Check valves (if present)
CGO
Gas pressure = slightly above atmospheric pressure
What are the 5 tasks of oxygen in the AGM?
-O2 pressure failure alarm
-O2 pressure failure device (failsafe)
-O2 flowmeter
-O2 flush valve
-Drives the ventilator
What are the maximum pressures and volumes for cylinders?
Air = 1,900 PSI and 625 L
Oxygen = 1,900 PSI and 660 L
Nitrous Oxide = 745 PSI and 1590L (20.7 lb when full, 14.1 lb when empty)
List 3 safety relief devices that prevent a cylinder form exploding when the ambient temperature increases
-Never expose to temps > 130F (57C)
- Fusible Wood’s plug that melts at high temperatures
- Frangible disk that ruptures under pressure
- Valve that opens at elevated pressures
Give 4 examples of how the hypoxia prevention safety device (proportioning device) can allow for a hypoxic mixture
- Pipeline crossover
- Leak distal to flowmeter valves
- Admin of a 3rd gas
- Defective mechanic or pneumatic components
Oxygen pressure failure device
-Failsafe
-Shuts off nitrous when oxygen drops below 20 PSI
Describe the structure and function of the flowmeters
Variable orifice constant flow
-The annular space is the space between the indicator float and the side wall of the flow tube. It is narrowest at base, and widest at the top
-Base = laminar flow (Poiseulle) based on viscosity
-Top = turbulent flow (Graham) based on density
An AGM uses FGF coupling .. how do you determine total TV that will be delivered to patient
- Convert FGF to mL/m
- Multiple mL/m x I:E ratio
- Calculate MVe
- Add MVe plus the #2
When using a ventilator that couples FGF to TV, what types of ventilator changes will impact the Tv delivered to the patient
Vt increases with: decreased RR, increased I:E ratio (1:1), increased FGF, increased bellows height
Vt decreases with: increased RR, decreased I:E ratio (1:2), decreased FGF, decreased bellows height
What does the oxygen analyzer measure, and where is it located?
Monitors oxygen concentration and is the only device downstream of the flowmeters that can detect a hypoxic mixture.
Oxygen flush valve
35 - 75 LPM
50 PSI
Describe the function of the ventilator spill valve in relation to using the O2 flush valve
The spill valve is closed during inspiration so if you press the oxygen flush valve during inspiration … the patient is at high risk for barotrauma
What is desiccation
Water is required to facilitate the reaction of carbon dioxide with CO2 absorbent. The granules are hydrated to 13 - 20% by weight. When the absorbent is devoid of water, it is desiccated.
It produces carbon monoxide des > iso > sevo and compound a with sevo
What are the OSHA recommendations regarding inhalation anesthetic exposure
Halogenated agents alone < 2 ppm
Nitrous oxide alone < 25 ppm
HA + NO < 0.5 and 25 ppm
Which mapleson circuit is most efficient for spontaneous ventilation? Which one for controlled Ventilation?
Spontaneous
A > DFE > CB
CMV
DFE > BC > A
What conditions decrease pulmonary compliance? How does this affect the peak pressure and plateau pressure?
D/t decreased static compliance (PIP and PP increase)
-endobronchial intubation
-pulmonary edema
-pleural effusion
-tension pneumothorax
-atelectasis
-chest wall trauma
-abd. insufflation
-ascites
-t-burg
What conditions increase pulmonary resistance? PP vs PIP
D/t reduction in dynamic compliance (PIP increases, PP unchanged)
-kinked ETT
-ETT cuff herniation
-Bronchospasm
-Secretions
-Airway compression
-Foreign body aspiration
Describe the four phases of normal capnograph
1 = exhalation of anatomic dead space
2 = exhalation of anatomic dead space and alveolar gas
3 = exhalation of alveolar gas
4 = inspiration of fresh gas that does not contain CO2
Describe the significance of the alpha and beta angles on the capnograph
Alpha = resistance. airflow obstruction. COPD, bronchospasm, kinked ETT
Beta = increased with some breathing
Pulse oximeter basics
Beer Lamber Law
660 nm (deoxyHgb)
940 nm (oxyHgb)
What conditions impair the reliability of pulse oximeter
Vasoconstriction, hypothermia, reynaud’s
carboxyhgb (absorbs 660nm same degree as oxygenated Hgb)
metHgb (absorbs 660 and 940 equally)
methylene blue, indocyanine green, indigo carmine
CPB, LVAD
What affects the accuracy of the NIBP cuff
Length = 80%
Width = 40%
Falsely increased BP
BP cuff too small
BP cuff too loose
Below level of the heart
Falsely decreased BP
BP is too large
Deflated too rapidly
Above level of the heart
How does the site of measurement affect BP monitoring
As the pulse moves from the aortic root toward the periphery, the systolic pressure increases, the diastolic pressure decreases, and the pulse pressure widens. MAP remains constant throughout the arterial tree
*At aortic root, SBP is the lowest, DBP is the highest, PP is the most narrow
*At dorsalis pedis, SBP is the highest, DBP is the lowest, PP is the most wide
How does the arm position affect NIBP?
Located above the heart, BP reading will be falsely decreased
Located below the heart, BP reading will be falsely increased
*For every 10 cm, BP changes by 7.4 mmHg
*For every inch, BP changes by 2 mmHg
Systolic BP = what on an a-line
Peak of waveform
Diastolic = trough
Contractility on an a-line is measured by? Stroke volume?
Upstroke
SV = AUC
Damping and interpretation of the high pressure flush test
High pressure flush helps us determine this when we observe oscillations that result
-Optimally dampened = 1 oscillation
-Under dampened = Lots of oscillations (SBP overestimated, DBP underestimated)
-Over dampened = No oscillations (SBP underestimated, DBP overestimated) d/t air bubble, clot, low flush bag pressure
How do you determine the appropriate distance to thread a central line
- Distance from site of entry to vena cava
- Distance from VC junction to where catheter tip should be placed
- Add them together
Insertion site to the vena cava
Subclavian = 10 cm
IJ right = 15 cm
IJ left = 20 cm
Femoral = 40
Median basilic rt, lt (40,50)
VC –> Catheter tip
Right atrium = 0 - 10 cm
RV = 10 - 15 cm
PA = 15 - 30 cm
PAOP = 25 - 35 cm
Discuss the 3 waves, 2 descents on CVP tracing
a = RA contraction
c = tricuspid valve elevation into RA (after QRS)
x = downward movement of contracting RV (ST)
v = RA passive filling (T wave)
y = RA empties through tricuspid valve
when do you lose an a wave on the cvp
a fibb, v-pacing w/underlying asystole
what causes an increased a wave on cvp
stenosis
MI
chronic lung dx = RVH
av dissociation
junctional rythm
PVCs
What causes a large v wave on cvp
tricuspid regurg
increase in intravascular volume
rv papillary muscle ischemia
where should the tip of the PAC locate
west zone 3
part > p venous> p alveolus
equation for mixed venous oxygen saturation
sao2 - vo2/ (q * 1.34 * hgb * 10)
What are the 12 leads
Bipolar (3) I - III
Limb (3) avr, avl, avf
Precordial (6) v1-v6
Name the region of the heart & leads
II, III, avf = inferior, RCA
I, avL, v5, v6 = lateral, circumflex
v1 - v4 = LAD
V1 & V2 (septum) V3 & V4 (anterior)
right axis deviation
anything with the lungs
left axis deviation
chronic HTN
LBBB
As
AI
MR
Class IA, IB, IC antiarrythmics
Na Channel Blockers
IA = quinidine, procainamide, disopyramide
moderate depression of 0, prolongs phase 3 repolarization
IB = Lidocaine, Phenytoin
shortened phase 3 repol
IC = flecainaide, propaferone
strong depression of phase 0
Class II antiarythmics
BB - slows phase 4 depolarization in the SA node
Class III antiarythmics
K Channel BLockers
Amio, Bretyium
Prolongs phase 3 repolarization (prolongs QT)
increases effective refractory period
Class IV antiarrythmics
Ca Ch Blockers
Decreasing conduction velocity through AV node
Verapamil, Diltiazem
EKG findings w/WPW
Delta wave d/t ventricular preexcitation
Short PR interval < 0.12 seconds
Wide QRS
Possible T wave inversion
What conditions increase the risk of torsades de pointed?
POINTES
P = phenothiazines
O = Other meds (methoadone, droperidol, amio)
I = ICH
N = No known cause
E = electrolytes … low K, Ca, Mg
S = syndromes (romano-ward, timothy)
Five indications for cardiac pacemaker insertion
Symptomatic diseases of impulse formation (SA node disease)
Symptomatic diseases of impulse conduction (AV node disease)
Long QT syndrome
Dilated CM
Hypertrophic obstructive cardiomyopathy
Pacemaker identification code
1 = chamber paced
2 = chamber sensed
3 = response to sensed event
4 = programmability
5 = can peace multiple sites
What conditions increase the risk of failure to capture?
Potassium high or low
Low CO2 (intracellular K+ shift)
Hypothermia
MI
fibrotic tissue around pacing leads
Cerebral oximetry utilizes NIRS
-CBV = 1 part arterial to 3 parts venous, 75% of the blood in the brain is on the venous side of circulation
-NIRS cannot detect pulsatile blood flow, it is primarily a measure of venous oxyhemoglobin saturation and oxygen extraction
-greater than 25% change in baseline = reduction in cerebral oxygenation
Beta waves
high frequency
low voltage
awake mental stimulation or light anesthesia
Alpha waves
awake, but restful state
Theta
GA and normal sleep with kids
Delta
GA, deep sleep, brain ischemia or injury
Burst suppresion
GA, hypothermia, CBP, cerebral ischemia
GA and brain waves
increased beta wave
theta, delta waves predominate during GA
deep GA produces burst suppression
1.5 - 2 MAC = complete suppression
name 2 drugs that reduce the reliability of the BIS value
nitrous oxide (increaases the amplitude of high-frequency activity and reduces the amplitude of low frequency activity)
ketamine increases high frequency amplitude
Macro vs micro shock
Macro = large current, external surface of the body. Skin offers high resistance so it takes a larger current to induce ventricular fibrillation
Micro = small current, directly to myocardium
Thresholds for macro/micro shock
Macro
1 mA = perception
5 mA = harmless threshold
10 - 20 mA = let go current
50 mA = LOC
100 mA = vfibb
Micro
10 microamps = max allowable in OR
100 microamps = vfibb
What is the role of the line isolation monitor?
Assesses the integrity of the ungrounded power system in the OR. Tells you how much current could flow through you if a second fault occurs
Alarms when 2 - 5 mA is detected
Unplug your last equipment you plugged in if it alarms!!
