EXAM 2 Review Content Flashcards
What is an oxygen cylinder’s max pressure and volume
2,000psi and 660L
What is a Nitrous Oxide cylinders max pressure and volume
745psi and 1590L
What is a Nitrous Oxide cylinders max pressure and volume
745psi and 1590L
When is the spill valve open and closed
Closed during inspiration
Open during expiration
The transfilling valve, aka yoke hanger check, aka check valve/outlet check valve, has what function:
Prohibits trans filling of other cylinders
The O2 flush valve delivers oxygen at what pressure and volume
50psi
35-75L
Describe this TEG
Normal
Describe this TEG
Anticoagulation or Factor Deficiency
Describe this TEG
Reduced platelet count or function
Describe this TEG
Primary Fibrinolysis
Describe this TEG
Hypercoagulation
Describe this TEG
DIC Stage 1: hypercoagulable state with secondary fibrinolysis
Describe this TEG
DIC Stage 1: hypercoagulable state with secondary fibrinolysis
Describe this TEG
DIC Stage 2: HyPOcoagulable state
In the brain, what is going to determine if fluid stays in the vasculature/pulls into the vasculature or pushes into the interstitium?
Blood-Brain Barrier
Sodium is less permeable. Making it the primary determinant over plasma proteins.
You give an isotonic solution into the intravascular space. What is going to happen to that solution?
A portion will stay in the intravascular space, but a portion of it, in about 30min, ~75%, will be lost to the interstitial space to reach equilibrium.
HESes are associated with?
Could you pick out what they are not associated with?
Kidney injury
Dialysis requirements
coagulopathy
sepsis
and increased mortality
What would be some reliable means for determining where your patient is on the Frank-Starling Curve?
● Edema, turgor, mucous membranes, cap refill, auscultate (hands on assessment)
● Pulse contour analysis (PPV >13% fluid responsive, <8% pressor responsive)
● NOT CVP, MAP OR UO
What might happen if you did a volume resuscitation with Normal Saline?
Hyperchloremia - Metabolic Acidosis
If you hypoventilated a patient - what would that do to your acid-base balance? Therefore, what would it do to your electrolytes?
Create respiratory acidosis –> more calcium and potassium shifts or is released into intravascular fluid.
You need to do an emergent C-Section on an eclamptic patient; what anesthetic drug has an increased risk profile in that circumstance?
(typically because of an electrolyte abnormality)
Magnesium potentiates the effects of Nondepolarizing neuromuscular agents. May need extra reversal agent.
Stop mag and reverse with CaCl
If you need to expand the plasma volume in a patient with a traumatic head injury, what fluid would you pick?
Hypertonic Saline Solutions of 3% or greater.
Promote volume expansion that mobilize intracellular and interstitial fluid into the vascular space. May protect patients with intracranial hypertension.
Fluid in the capillary bed going from the capillary side to interstitial or interstitial to the capillary. What changes would you expect if the patient had a low cardiac output state?
Acute drop in CO due to anesthesia will drop capillary hydrostatic pressure. Creating a net negative pressure pulling fluid INTO the intravascular space.
Calculate a maintenance fluid rate using the 4:2:1 rule.
4ml/kg for the first 10kgs
2ml/kg for the second 10kg
1ml/kg for the remaining
If greater than 20kg, add 40 to find the maintenance rate
If you needed to devise a fluid plan for a hypovolemic patient, what fluid would you choose?
Isotonic: LR or NS
Your patient is going to have surgery; they’re going to have an incision; what things can lead to evaporative losses?
Sweat, Breathing, Surgical exposure of body cavaties
Your patient has Hyperkalemia and you have these EKG changes: Loss of P wave and widening QRS; immediate effective therapy is indicated, what do you administer?
- IV Calcium Chloride - 10mL of 10% CaCl over 10-min period
or
10mL of 10% Calcium Gluconate over 3-5min - IV Sodium Bicarb, 50-100mEq over 10-20min
Which yields more ionized calcium, CaCl or CaGluconate?
CaCl = 27mg/mL
Gluconate = 9mg/mL
What is the onset of Calcium Chloride or Calcium Gluconate?
1-3 minutes
What is the duration of action of Calcium Chloride or Calcium Gluconate?
30-60minutes
Why give calcium for hyperkalemia?
Stabilizes cardiac membrane
Bicarbonate administration for Loss of P wave and widening QRS due to hyperkalemia takes how long to take effect?
5-10minutes
Bicarbonate administration for loss of P wave and widening QRS due to hyperkalemia lasts for how long?
1-2 hours
Bicarbonate administration for Loss of P wave and widening QRS due to hyperkalemia has what mechanism of action?
Shifts potassium intracellularly
Your patient has hyperkalemia and Peaked T waves that need prompt therapy; what do you do?
- Glucose and Insulin Infusion:
IV of 50mL D50W and five units regular insulin - Urgent hemodialysis
Administration of IV D50W 50mL and five units regular insulin for hyperkalemia takes how long to onset?
30 minutes
Administration of IV D50W 50mL and five units of regular insulin for hyperkalemia has a therapeutic duration of?
4-6 hours
What is the mechanism of action of glucose and insulin administration in a hyperkalemic patient?
Shifts potassium intracellularly.
What should you do if the patient has hyperkalemia but no EKG changes?
- Administer potassium-binding resins in GI tract
- Promotion of renal excretion via loop diuretics.
How long does oral potassium binding resins take to onset? Have a duration of?
Onset: 1-2 hours
Duration: 4-6 hours
Administration of furosemide 40mg for hyperkalemia usually has an onset of? And a duration of?
Onset: 15-30 minutes
Duration: 2-3 hours
Pts who should not receive colloids/albumin:
Neurotrauma
Endothelial injuries / impaired glycocalyx —> pulm edema, end-organ damage (Sepsis, Lg Vascular Traumas)
Hypocalcemia
Hyperglycemia (DM)
Pts who can receive colloids:
-Volume loss not from active bleeding
-Hypovolemic pts with Intact glycocalyx
- Pts with lower capillary oncotic pressure such as liver pts with
hypoalbuminemia
The causes of OR fires are primarily from?
Electrocautery - 90%
Lasers - 10%
What percent of OR fires occur during high risk cases involving the head, neck, and upper chest?
85%
What percent of OR fires involve the airway? Head and Neck?
34% airway
28% head and neck
If you know or suspect patient inhalation injury from toxic fumes: ex - CO, HCL, Cyanide - the patient is at risk for? What should your actions be?
At risk for airway edema. Look quickly, if any indication, including airway/voice hoarseness, intubate immediately.
You can always extubate later the same day.
What are the three components of the fire triangle?
Fuel Source
Ignition Source
Oxidizer
What are some Fuel Sources in the OR
surgical prep and alcohol [Allow to dry!]
petroleum ointments, facial hair, drapes, gloves, breathing circuits, dressings, ETT
What are some Ignition Sources in the OR
ESUs, fiberoptics, high-speed drills, laser, monitors, defibs, desiccated soda lime
What are some Oxiders in the OR
Air, O2, N2O
in 95% of cases it is O2 because it is heavier than air, and it accumulates around and under drapes
What are some surgical fire prevention strategies
-Avoid open air O2 delivery. ETT (closed) or LMA (less closed but more than open)
-Communicate fire sources and if O2 requirements are raising in ESU cases
-Coat facial hair with water-soluble lubricant
-Laser resistant ETTs
-Moistened sponges
-Flame retardant drapes
When using O2 in an ESU procedure. The supplemental O2 should be less than what % and off for how many minutes before ESU use?
Less than 30% and off for 1min prior
Anesthesia providers are responsible for what portion of the fire triangle
Oxider
What steps should be taken if an airway fire occurs?
- Stop ventilation and remove ETT
- Stop flow of all gases
- Remove all other flammable material away from airway
- Pour water or saline into airway
- Fire extinguisher if water did not clear fire (BC extinguisher)
- Assess for airway edema / trauma
- Consider steroid admin
- Monitor in ICU for 24 hours
- Report to joint commission and FDA
To avoid a blow torch effect, what should you NOT do when extubating the patient because of an airway fire?
do not squeeze the reservoir bag
Why do O2 devices ignite easily?
They contain polyvinyl chloride (PVC)
What does RACE stand for
Rescue
Alarm
Contain
Extinguish
What does P.A.S.S. stand for
Pull pin
Aim at base of fire
Squeeze
Sweep side to side
Laser light differs from ordinary light because of what three things:
- Monochromatic - single wavelength
- Coherent - light oscillates in the same phase
- Collimated - exists as a narrow parallel beam
Long wavelength lasers absorb _____ ____ and (do or do not) penetrate deep into tissue
Absorb more water and do NOT penetrate deep into tissue
Short wavelength lasers absorb _____ ____ and (do or do not) penetrate deep into tissue
less water and DO penetrate deeper into tissue
CO2 lasers require what color eye protection to protect which eye structure
Clear lenses - cornea
Nd:YAG lasers require what color eye protection to protect which eye structure
Green goggles - Retina
Ruby lasers require what color eye protection to protect which eye structure
Red goggles - Retina
Argon lasers require what color eye protection to protect which eye structure
Amber goggles - Retina
The decision to transfusion PRBC should be based on?
Insufficient DO2 (oxygen delivery)
Hg <6 (almost always); Hg <7 (depends); you are transfusing RBC’s to improve DO2: arterial oxygen delivery, mixed venous, central venous oxygen sat; transfuse if there’s signs of improper DO2: lactate levels, signs of cardiac ischemia: hypotension, tachycardia
Describe the differences between:
Type
Screen
Cross
Type: ABO and Rh status.
Screen: Screens for more rare antibodies. [45min]
Cross: “test transfusion” mixes donor blood and patient blood. It greatly reduces the likelihood of transfusion rxn. [45min]
What are 5 procoagulants
Coagulation Factors
Collagen
vWF
Fibronectin
Thrombomodulin
What are 4 AntiCoagulant mediators?
AntiThrombin III
Protein C
Protein S
Tissue Pathway Factor Inhibitor
What are two vasodilatory mediators
Nitric Oxide and Prostacyclin
What are three vasoconstrictor mediators
Thromboxane A2
ADP
Serotonin
What are three fibrinolytic mediators?
Plasminogen
tPA (tissue plasminogen activator)
Urokinase
What kind of mediator is Plasminogen classified as? :
What is its function?
Fibrinolytic
Converts to plasmin
What kind of mediator is tPA classified as? :
What is its function?
Fibrinolytic
Activates plasmin
What kind of mediator is Urokinase classified as? :
What is its function?
Fibrinolytic
Activates plasmin
What are two anti-fibrinolytics?
Plasminogen Activator Inhibitor
alpha-antiplasmin
What kind of mediator is Plasminogen Activator Inhibitor
What is its function?
Antifibrinolytic
Inactivates tPA and urokinase
What kind of mediator is alpha-antiplasmin classified as? :
What is its function?
Antifibrinolytic
Inhibits Plasmin
What factors make up the Extrinsic Pathway
Factor 3 - Tissue Factor (Thromboplastin)
Factor 7 - Proconvertin Factor (labile)
Vitamin K is created by? And is it necessary for the formation of which factors?
Created from bacteria in the gut and is necessary for the formation (in the liver) of Factors 2, 7, 9, 10
What are two antifibrinolytic (anticlot breakdown) medications?
Aminocaproic Acid
Tranexamic Acid (TXA)
The PT lab value will be prolonged when patients have abnormalities or deficiencies in?
factors specific to the extrinsic (3 & 7) and common pathways (10, 9?, 2, 1)
What is a normal INR?
Apex: ~1
Nagelhout: 1.5-2.5
aPTT is used to evaluate the efficiency of the ____ and the common coagulation pathway. This includes which factors?
Intrinsic: 12, 11, 9, and 8
Common: 10, 5, 2, 1 and ultimately 13
Normal ACT
Apex: 90-120
Nagelhout: 90-150
ACT is used to measure?
Activated Clotting Time. Ability to clot. Also can be used to regulate heparin therapy.
TEGs provide an indication of what 5 processes?
- Clot Strength
- Platelet number and function
- Intrinisic Pathway defects
- Thrombin formation
- Rate of fibrinolysis
What are four very high risk for bleeding procedures? What should the minimum platelet count be?
Neurosurgery
Ocular surgery (except cataracts)
Thyroid Surgery
Prostatectomy
75,000-100,000 plts
What is the MABL (maximum allowable blood loss) equation?
MABL = EBV x (Starting Hct(or hgb) - Minimum acceptable Hct(or hgb) ) / all of the above divided by initial hematocrit (or hgb) level
Which blood product carries the greatest risk for bacterial transmission?
platelets
Fresh Frozen Plasma (FFP) contains?
All coagulation factors, especially factors 2, 7, 9, and 10
AND
Albumin (plasma proteins)
Fibrinogen
[Antithrombin 3, Protein C and S (hemostasis equilibrium)]
What lab values may indicate you should administer FFP?
PT and/or aPTT prolonged more than 1.5 times normal.
(FFP=Factors 2,7,9,10. Albumin. Fibrinogen.)
Long INR
Cryoprecipitate contains?
Factor 8 and 13.
Fibrinogen
vWF
Fibronectin
Describe Type 1 and 2a vWF disease and how you would treat it before surgery?
Mild-moderate reduction in vWF production. Treated with Desmopressin (0.3mcg/kg)
Cryo if there is no response or availability of Factor 8 concentrate.
Describe Type 2b and 3 vWF disease and how you would treat it before surgery?
vWF is not produced or doesn’t work correctly.
Bleeding patients with type 3 should be given vWF/Factor 8 concentrate or Cryo.
Desmopressin will not work.
What coagulation lab values would you expect in a patient with Hemophilia A? What would be the treatment before surgery?
PTT increased and PT normal
Mild - can try DDAVP (vWF carries factor 8 around)
Factor 8 Concentrate before surgery
Cryo (has more Factor 8) > FFP
Recombinant Factor 7 last-ditch effort
What coagulation lab values would you expect in a patient with Hemophilia B? What would be the treatment before surgery?
PTT increased and PT normal. Remember Factor 9 is on intrinsic pathway.
Factor 9 - Prothrombin Concentrate Complex
FFP
Recombinant Factor 7 last-ditch effort
NOT desmopressin. Has no effect on Factor 9
Lab Values Consistent with DIC
Decreased Platelets [less than 100]
Decreased Fibrinogen [under 150]
Decreased AntiThrombin [less than 80%]
Increased D-Dimer [over 500]
Increased PT[over 14] or aPTT[over 32]
What is the universal FFP donor and acceptor?
Donor: AB
Acceptor: O
Pt needs surgery. You have a patient taking Warfarin, INR is high, what do you do?
If you have time: Vitamin K to reverse (takes a few hours)
If it’s emergent: FFP or Prothrombin Complex Concentrate
What extrinsic factor is produced in the liver?
Factor 7
Produced in the liver. Vitamin K required for synthesis
What are the factors of the final common pathway
10, 5, 2, 1, and 13
What are the intrinsic factors
12, 11, 9, 8
How does Heparin work?
It binds to antithrombin and accelerates its anticoagulant ability 1,000 fold. (remember ATIII corrals 12, 11, 10, 9 and 2)
Inhibits intrinsic, common pathway, and plt function
Pt looks to be in DIC. You need to administer something before OR, what are three things you could choose from?
FFP
Plts
Cryo
Injured blood vessel - what mediators are released
Procoagulants
and
Thromboxane A2
ADP
vWF
Patient needs a craniotomy, what is the minimal plt value needed
75,000-100,000
How do you transfuse a woman of childbearing years?
Give O neg to prevent Rh+ antibodies develop
Disease description of hypercoagulable state
HIT type 2
DIC
Vasooclusive crisis SCD
How much does Hgb and Hct change after one unit PRBC
1 hgb unit
2-3% Hct
Describe HIT Type I
Non-Immune Mediated
Onset typically 1-4 days start of heparin
Mild thrombocytopenia <100,000
Often resolves spontaneously
Not associated with thrombosis and death
Describe HIT type II
Immune Mediated - IgG
Onset typically 5-14 days after start of heparin
Severe thrombocytopenia < 60,000
Does not resolve spontaneously - heparin should be stopped
Associated with thrombosis and mortality
What are the effects of being banked on blood?
Decreased 2,3-DPG
Decreased ATP
Decreased pH (acidosis)
Hypocalcemia
Increased Potassium - Hyperkalemia
Impaired shape/morphology
Hemolysis
Absence of factors 5 and 8
Increased proinflammatory mediators
Recommendations for PRBC infusion for adults PRBC:Pt blood loss ratio
1mL PRBC for every 2mL blood loss
In an MTP, what is the recommended plasma:PRBC infusion ratio
1:1-2
In an MTP, what is the recommended plt:PRBC infusion ratio
1 plt per 6 PRBC
How does MTP of banked blood change the oxyhemoglobin curve
Left Shift. Decreased 2,3 DPG and conversion of citrate to sodium bicarb leads to alkalosis.
Hgb holds on to oxygen longer, delaying release into tissues.
What organization is responsible for the compressed gas cylinders?
Department of Transportation
What organization is responsible for the scavenger system?
OSHA
occupational safety and health administration
Normal working pressure of gas machine?
50 psi
What is the DISS? How does it work?
Diameter Index Safety System
The pipeline inlet for the fresh gases (oxygen, air, n20) has different sizes/threads that only correspond to the appropriate gas tubing. And a check valve ensures unidirectional flow.
The pipeline pressure gauges should read about what psi?
50 psi
Who sets the standards for the required components of the anesthesia machine?
ASTM
American Society for Testing and Materials
What monitors for low oxygen pressure in the anesthesia machine?
oxygen pressure failure device
What pressure system does the oxygen pressure failure device (failsafe device) reside in?
intermediate pressure system
The oxygen pressure failure device (failsafe device) will not alarm in the setting of?
pipeline crossover
crack in glass flow meter
What are the two components of the oxygen pressure failure device (failsafe device) that prevent a hypoxic mixture?
- Threshold alarm: sounds when oxygen pipeline pressure falls below 30psi
- Pneumatic system: reduces or stops the flow of n20 when the pressure in the oxygen pipeline falls below 20psi
Will your machine alarm if it switches to cylinder oxygen instead of the pipeline if you accidentally leave the cylinder valve open?
No!
Max Service pressure for oxygen cylinder
1900 psi (2,000 acceptable for calculations)
Max Service Pressure for Nitrous Oxide
745psi
Max service pressure for air
1900psi
A full oxygen tank contains how many Liters of oxygen
660L
How do you calculate how much time you have left on an oxygen cylinder at a given flow rate?
Tank Capacity / Full Tank (service) pressure
=
contents remaining (L) / current gauge pressure
This gives you Liters remaining. Then take the Liters remaining divided by the flow rate (L/min) to give you how many minutes you have left before the tank expires
Is nitrous oxide stored as a liquid or gas?
Liquid and turns to gas when close to empty (1/4 left)
At what rate of N20 would create frost on its wall or freeze the valve?
4L/min
Anesthesia machines will have at least how many minutes of battery if loss of power occurs
30 minutes
The traditional flowmeter (Thorpe Tubes) are the beginning of what system? It controls and measures the fresh gas flow that travels towards the?
Low-pressure system
Vaporizers and common gas outlet
Describe the Link-25 Proportioning System to prevent a hypoxic mixture
A mechanical system linking N2O and O2 with a chain around the flow meter knobs. It prevents a serious hypoxic mixture by limiting the ratio of N20 and O2 to a 3:1 ratio.
Oxygen Flush can supply how much oxygen?
35-75 L/min flow
Thorpe Tubes / Flow Meter Tubes are in which pressure system of the anesthesia gas machine?
Low Pressure System
Cylinder Pressure Regulators are in which pressure system of the anesthesia gas machine?
High Pressure System
Hanger Yokes are in which pressure system of the anesthesia gas machine?
High-Pressure System
Pipeline inlets are in which pressure system of the anesthesia gas machine?
Intermediate Pressure System
Vaporizers are in which pressure system of the anesthesia gas machine?
Low-Pressure System
Flow Meter Valves are in which pressure system of the anesthesia gas machine?
Intermediate Pressure System
Oxygen pressure failure device (aka oxygen failsafe device) is in which pressure system of the anesthesia gas machine?
Intermediate Pressure System
Oxygen Flush Valve is in which pressure system of the anesthesia gas machine?
Intermediate Pressure System
Cylinder Pressure Gauge is in which pressure system of the anesthesia gas machine?
High-Pressure System
Common Gas Outlet is in which pressure system of the anesthesia gas machine?
Low-Pressure System
List the 5 tasks of oxygen in the anesthesia gas machine
- O2 Pressure Alarm
- O2 Pressure Device
- O2 Flowmeter
- O2 Flush Valve
- Ventilator Drive Gas
The bourdon pressure gauge on an oxygen cylinder reads 500psi. If the flow rate is 2L /min, how much time do you have left?
660L/2000psi = Contents remaining/500psi
contents remaining / 2L = minutes left
83minutes
Who developed the Anesthesia Machine Pre-Use Checkout Procedures
FDA
What is the purpose of the oxygen failsafe device?
to monitor for (and protect against) low oxygen pressure in the anesthesia machine
The oxygen failsafe device will alert you to what 3 problems?
- Depleted O2 tank
- A drop in pipeline pressure
- Disconnected O2 supply hose
What is another name for the oxygen failsafe device?
Oxygen Pressure Failure Device
What is the difference between the oxygen pressure device and the hypoxia prevention safety device regarding nitrous oxide?
OPD is a failsafe device. It shuts off and/or proportionally reduces Nitrous Oxide flow if O2 pressure drops below 20psi
HPSD is a proportioning device. Prevents you from setting a hypoxic mixture with the flow control valves.
If asked to calculate the total tidal volume delivered to the patient, including FGF coupling, what are the steps?
FGF = 4/L min
I:E= 1:2
RR: 10/min
Vt: 500
633mL
What hazards are associated with activating (pushing) the oxygen flush valve during a procedure?
- Risk of Barotrauma
- Patient awareness
What could occur if the first-stage oxygen regulator in the anesthesia machine is faulty?
Depletion of oxygen tank
The first-stage regulator allows the preferential use of the pipeline oxygen when the higher pressure in this system is sensed. This regulator prevents the use of cylinder oxygen even if it is left on. But if the regulator is faulty, you would deplete the cylinder because it has a higher pressure than the pipeline.
What is the best indicator of anesthesia circuit disconnect?
A. Absence of CO2 waveform
B. Low expired tidal volume
C. Decreased minute ventilation
D. Set pressure threshold not reached
A
What is the equation for desflurane vaporizer % when changing altitude
Required Dial Setting = (sea level v/v% x 760) / current barometric pressure
When using mechanical veniltation, the low inspiratory pressure alarm should be set to?
within 5cm H2O below peak pressure
thus detecting disconnection and minor to moderate leaks
What are 2 reasons the positive pressure alert system may alarm?
Expiratory Valve Malfunction (ventilator spill valve)
Faulty unidirectional valve
What is the pumping effect?
Anything that causes gas that has already left the vaporizer to re-enter the vaporizing chamber.
What can create the pumping effect?
Positive Pressure Ventilation
What 2 functions does the drive gas on a pneumatic ventilator serve?
- It compresses the bellows
- It opens and closes the ventilator spill valve
What is the position of the ventilator spill valve during inspiration?
Closed. This ensures that the tidal volume goes to the patient and not to the scavenger
How does an ascending bellows move during inspiration
it falls
Will a descending bellow fill during a circuit disconnect?
Yes - it can fill with entrained room air
How is gas flow delivered in volume-controlled ventilation
Inspiratory flow is held constant during inspiration.
If airway resistance rises or lung compliance decreases, then PIP will?
Peak Inspiratory Pressure will increase
What are the fixed factors in Volume Controlled Ventilation
Tidal Volume
Inspiratory Flow Rate
Inspiratory Time
What are the fixed factors in Pressure Controlled Ventilation
Peak Inspiratory Pressure
Inspiratory Time
What is the dependent variable in Volume Controlled Ventilation
Peak inspiratory Pressure
What are the dependent variables in Pressure Controlled Ventilation
Tidal volume
Inspiratory Flow
Situations where PCV is better than VCV
Patient has low compliance: Pregnancy, Obesity, Laparoscopy, ARDS
High PIP would be dangerous: LMA, Neonate, Emphysema
Need to Compensate for a Leak: LMA, Uncuffed ETT in children
What modes of mechanical ventilation are best suited for laryngeal mask airway?
SIMV (synchronized intermittent mandatory ventilation)
PSV (pressure support ventilation)
Describe Pressure-Control Ventilation with Volume Guarantee (PCV-VG)
PCV-VG offers the benefits of pressure control ventilation but also guarantees a predetermined tidal volume while applying the minimum required pressure.
(useful because sometimes laparoscopic surgery or patient positioning can change the tidal volume a patient can take)
Describe Pressure-Support Ventilation (PSV)
Augments spontaneous breaths with a pre-set amount of pressure support. No machine-initiated breaths unless there is a back-up rate if apnea is detected (PSV-Pro)
What is the difference between CPAP and PSV
CPAP delivers a continuous amount of pressure throughout the respiratory cycle. Augments inspiration and reduces airway collapse during expiration.
PSV only applies pressure to the circuit when the patient initiates a breath: Used to support spontaneous breaths by decreasing the patient’s effort during inspiration. It helps increase tidal volume, reduce the workload of respiratory muscles, and improve ventilation efficiency
Describe Biphasic Positive Airway Pressure (BiPAP)
two levels of pressure are set
P1 = inspiratory positive airway pressure
P2 = expiratory positive airway pressure
Basically, it combines PSV and CPAP
What is the ideal mesh size for CO2 absorbent?
4-8 mesh
To maintain constant pressure inside the breathing circuit, the scavenger must only remove an amount of gas equal to?
Fresh gas flow minus the volume of gas lost due to the patient’s oxygen consumption
The APL valve controls?
The amount of gas that remains in the circuit and the amount that is released to the scavenger during spontaneous ventilation
The ventilator spill valve determines?
The amount of gas that remains in the circuit and the amount that is released to the scavenger during mechanical ventilation
Does an Open scavenger system have an active or passive scavenging interface?
Active Only. Suction provides the negative pressure. If this is occluded, gas leaks into the OR via the scavengers open windows
An open scavenging interface interacts with the OR environment. What happens if too much or too little suction occurs?
If there is too much suction, room air is entrained(pulled) into the system.
If there is too little suction, the scavenge system will release its contents into the OR environment.
Does a closed scavenging interface an active, passive, or either scavenging system?
Can be either
What does a closed scavenging interface require for a passive scavenging system?
A positive pressure relief valve - to prevent barotrauma in the event of distal obstruction
What valves must be present in a closed scavenging system with an active interface?
Both a positive and negative pressure relief valve.
This protects against excess negative pressure by entraining room air if there is too much negative pressure and releasing contents into the OR if there is too much positive pressure.
What is the most common cause of low circuit pressure?
Circuit Disconnect at the Y-piece
The second most common - leak around the carbon dioxide absorbent
According to OSHA, recommended standards what is the Maximum accepted level of exposure to halogenated agents with and without nitrous oxide in use?
2ppm Halogenated Gases
When nitrous is in use, 0.5ppm halogenated and 25ppm nitrous
What circuit contains a reservoir bag but does not allow rebreathing of exhaled gases?
Semiopen
Can SIMV be set to a pressure control or a volume control?
Yes. Can do either.
Where do the high-pressure and intermediate-pressure systems in the AGM interface?
At the pressure regulators between cylinders and pipeline
What things shorten the lifespan of the CO2 absorber?
Prolonged FGF - desiccation
Not shaking the canister to mix up the granules creating a channeling effect.
Not having absorber on the inspiratory limb
What is the optimal granule size of CO2 absorbents?
1/8 - 1/4 in.
What is the water content of SodaLime
Absorbents are manufactured to have a water content between 13% and 20% by weight.
Spit some facts about SodaLime
Turns purple (ethyl violet) when pH <10.3
Desiccation increases byproducts
-Sevo –> compound A
- Des and Iso –> CO
Majority Ca(OH)2
Does not regenerate - my change back to white
What DISS connections are on an anesthesia workstation?
Air, N2O, O2
and
Scavenger suction
If you had to go in and check a machine quickly/emergently. What three things would need to be checked?
Suction
Back-up ventilation equipment
High-Pressure Leak Test - to ensure positive pressure ventilation is available
What does a semi-closed breathing circuit have in common with a closed breathing circuit?
Some amount of rebreathing
Both have reservoirs
You’re in the middle of a case. Pt is starting to get tachycardic and HTN. You turn up your gas but your agent is actually going down. What do you think is going on?
Gas empty
Patient Disconnect
Vaporizer Leak
-o ring
-loose filler cap
Your bellows collapse. What would and what wouldn’t cause that?
Disconnect
Failure of negative pressure relief valve
Open spill valve
You lose your oxygen source, your pipeline source. But you have a piston-driven machine. What steps do and don’t you have to take?
You do not need to ventilate manually.
Open cylinders and phone a friend.
Your patient becomes disconnected. What are multiple ways you might know that? What would not tell you if they become disconnected or not?
Low TV alarm
● Low PIP alarm
● Drop off of Co2 waveform
● No auscultation
● No chest rise or fall
● Reservoir bag not filling/emptying
● Deflated bellows (exhalation in standing)
● Late is low pulse ox
O2 analyzer will not alarm with a patient disconnect
You have a certain kind of patient. Plan your anesthetic for your anesthesia workstation.
● Smoke inhalation or MH → want high FGF with no rebreathing → semi-open
● Pediatrics → low airway resistance → Mapleson
Vent settings: VC; RR 6, TV 500, I:E ratio 1:4. How much time does pt spend inspiring
60/5 = 12sec
Excess gasses & agents are managed through the use of:
● Scavenger
○ Via ventilator relief valve (aka spill valve) on bellows
○ Via APL valve on spontaneous ventilation
● CO2 absorber
Taking patients to the CT, plan O2 for the trip, need 30 min. E-Cylinder, 10L/min, need how much pressure in O2 tank minimum?
total capacity (L) / total pressure
Minutes x L/min
30min x 10L/min = 300L
Plug into formula to find psi instead of Liters
Needed capacity (L) / required pressure
300L/ ? pressure
909psi
The Law of Conservation of Electrical Charge states:
The total amount of electrical charge in the universe is constant. Charges are “simply” transferred.
Charges that move are what chemical species and what is their charge?
Negatively charged electrons.
What is electricity?
The flow of electrons - electron movement
All electrical charges have an associated:
force field
Stationary electric charges possess potential energy measured in joules. What is an example of a medical device that holds potential energy?
Defibrillator
What is a conductor?
Any substance that permits the flow of electrons. Most metals are due to mostly empty electron shells.
What is an insulator?
Any substance that does not allow the flow of electrons. Non-metallic.
Can insulators hold a charge?
Yes. It can hold a static charge. ex: defibrillator charging
What is an electrical current
The amount (magnitude) of charge flowing per unit time.
What is resistance in terms of electricity?
The energy required to push electrons through a material
What is an electrical circuit?
Electrical charge flowing through a closed path
What is a Direct Circuit (DC). Give an example
Current flows in one direction only.
Ex: Energy commonly battery powered
What is an Alternating Circuit (AC)
Give an example
Current periodically changes direction.
Ex: Derive energy from wall outlets or AC generators
Describe a Series Circuit
There is only one path that the current can take. Voltages and resistances are additive.
Describe a Parallel Circuit, give an example
Current can take more than one path. A unique current will flow through each resistor independently.
ex: household ciruits
What is electrical power?
Power is the rate at which energy is expended or consumed
What two variables impact Ohm’s Law
Resistance and Conductance
What does Ohm’s Law describe?
the voltage across a conductor is directly proportional to the current flowing through it, provided all physical conditions and temperatures remain constant.
Power consumed by am electrical circuit is measured in?
Watts
What is a semiconductor? What makes them “popular”?
Materials with conducting properties between those of insulators and conductors. The ability to control conductivity by the addition of small amounts of impurities “doping agents”
Semiconductors are most commonly prepared from?
Silicon
What are two types of semiconductors and what are they doped with?
P-Type: Positive type. Electron poor material composed of silicon and doped with Boron.
N-Type: Negative type. Electron rich material composed of silicon doped with Arsenic.
What are diodes?
Electrical current elements that have a large conductance in one direction and a smaller conductance in the reverse direction.
How is Spectroscopy used for in healthcare?
Analysis of blood work and oxygen pulse oximetry.
Substances in spectroscopy absorb complementary color, red absorbs??
Greeeeen
Beer’s Law describe the relationship between what three factors?
Absorptivity
Concentration of analyte
increasing the distance
What is transmittance?
Fraction of light passing through a sample. Influenced by intensity of the light.
What factors influence the strength of a shock?
The path of the current
The magnitude of the current
The duration of contact
What devices can produce an electric shock?
EVERY energized device or electrical circuit has the potential for producing an electric shock
What is a Macroshock
A relatively large amount of current flows through the body potentially resulting in injury or death
What is a Microshock?
A relatively small current is delivered externally and finds is way to the heart via a low-resistance pathway
A shock as little as _____ can casue ventricular fibrillation
100 uA
What are 3 modern electrical safety devices?
Polarized plugs
Three-pronged grounded plugs
Ground Fault Circuit Interrupters (GFCIs)
How do Fuses and Circuit Breakers provide safety?
Designed to prevent too much current from flowing because of a short circuit or circuit overlaid.
Fuse: contains a metal strip that heats up due to the resistance of the metal to the electrical current. If current exceeds the rated value of the fuse, metal strip will melt and stop current flow. Must be replaced.
Circuit: Same principle as fuse but metal bends instead of melts. Can be reset.
What are three items in the OR that use three-pronged plugs and grounded outlets?
IV pumps
Anesthesia Gas Machine
Cell Saver
Ground Fault Circuit Interrupters are usually used where?
Near water sources
To further reduce the likelihood of shock in the OR, most ORs use what kind of circuits?
Isolated Ungrounded Electrical Circuits
simply referred to as Isolated Circuits or Ungrounded Circuits
To make an Ungrounded Circuit, what is required?
An isolation transformer. Works through electromagnetic induction. No direct connection between the primary circuit [electrical source] and secondary circuit [site of electrical use].
What are Line Isolation Monitors
Indicates isolation circuit has been compromised. However, allows circuit to remain functional.
How do you identify the faulty piece of equipment setting off the line isolation monitor?
Sequentially unplugging one piece of equipment at a time until the indicated current on the LIM drops below the limit and silences.
What are the two types of Electrosurgery methods
Unipolar: requires grounding pad to complete circuit. Current passes through the body to grounding pad.
Bipolar: Utilizes two closest-spaced electrodes. Current flows between them and not through the rest of the body.
Thermal destruction of tissue through ESU creates what % of air contaminants
95% water
5% particulate matter, volatile gases, and microorganisms.
CO2 lasers produce contaminants equal to 3-6 cigarettes by burning how much tissue?
Only 1 gram!
Pacemakers are an electrical shock risk. What should be placed on them during surgery?
Magnet. Interrogate before and after surgery.
