Exam 1 Reading 2 (B.Ch25) Flashcards
Estimate the remaining number of hours that oxygen can be delivered from an E-cylinder of oxygen with a pressure of 1500 psig at an oxygen flow rate of 3 L/min.
2.5 OR 2.8
Which of the following is more likely to produce the pumping effect in an anesthetic vaporizer?
Using the Oxygen flush valve
The pumping effect is an intermittent back pressure caused by results in
positive pressure ventilation or use of the oxygen flush valve,
Pumping effect results in
elevated vaporizer output.
Pumping effect is more prominent with l
Low flows Low vaporizer dial settings Low levels of anesthetic in the vaporizer chamber High respiratory rates High peak inspiratory pressures.
Which law explains the relationship between the pressure and volume of a gas?
According to Boyle’s law, pressure and volume are inversely proportional. As pressure increases, volume decreases.
Compared to sea level, if you turn on a Tec 6 vaporizer at a high altitude, it will
Deliver a lower partial pressure of desflurane
If you set a Tec 6 vaporizer to 6% at 10,000 feet, it will still output a constant 6%, but since the atmospheric pressure is only 500 mmHg,
the partial pressure will decrease from about 45 mmHg to 30 mmHg.
Under normal conditions, as venous return to the heart increases, cardiac contractility also increases. This effect is referred to as the
Frank-Starling mechanism
Under most conditions, the amount of blood that the heart is able to pump is
directly related to the amount of blood that returns to it from the venous system. As more blood returns to the heart, it is able to adapt.
As the walls of the heart muscle are stretched further, the cardiac muscle will contract
more forcefully to eject the blood out. This occurs because the increased stretch lines the actin and myosin filaments in a more optimal position and allows them to contract harder. This effect is referred to as the Frank-Starling mechanism.
What is the approximate pressure within the hospital pipeline system?
50 psig
When a nitrous oxide cylinder is in the high-pressure circuit, the psig is:
750 Psig
At 760 mmHg, the boiling point of Desflurane in degrees Celsius is:
22.8
At standard pressure, the boiling points for inhalation anesthetics in degrees Celsius are: ISOFLURANE
48.5
At standard pressure, the boiling points for inhalation anesthetics in degrees Celsius are: HALOTHANE
50.2,
At standard pressure, the boiling points for inhalation anesthetics in degrees Celsius are: SEVOFLURANE
58.5
The vapor pressure of desflurane is __________ times that of other contemporary inhaled anesthetics.
The vapor pressure of desflurane is 3-4 times that of the other inhaled anesthetics and boils at 22.8 C which is slightly above normal room temperature.
The low-pressure circuit leak test evaluates the anesthesia machine from the______Except the
flow control valves to the common gas outlet. This includes the portion of the machine that is downstream from all safety devices except the oxygen analyzer
The cylinder pressure indicator is in the_______ pressure system.
intermediate
The maximum amount of CO2 that can be absorbed by soda lime is _____ L of C02 per 100 g of absorbent.
26 L of Co2 per 100g of absorbent
The amount of energy that is consumed by a given liquid as it is converted to a vapor is referred to as the:
The latent heat of vaporization
Oxygen can exist only in gaseous form at room temperature. Which gas law states that for a fixed mass of gas at constant temperature, the product of pressure times volume is constant?
Boyle’s ( is the VP)
The volume of oxygen available from the cylinder is
directly proportional to the cylinder pressure.
By weight, what is the largest component of high moisture soda lime?
Calcium Hydroxide
The composition of high-moisture soda lime is
80 percent calcium hydroxide
15 percent water
4 percent sodium hydroxide
1 percent potassium hydroxide.
The intermediate-pressure circuit has a pressure of about
45-50 psig.
What is the primary component of soda lime carbon dioxide absorbent?
Calcium Hydroxide
Is mercury in soda lime
No
Which of the following statements are true regarding the vaporizer pumping effect? (select two)
It can result in elevated vaporizer output
It is more prominent at high respiratory rates
Which term represents the speed at which heat flows through a substance?
Thermal conductivity
Which is the item most frequently missed in the preanesthesia setup?
self-inflating resuscitation bag.
What is the pH indicator added to soda lime to help assess the functional integrity of the absorbent?
Ethyl violet
Which is the only safety device that evaluates the integrity of the low-pressure circuit in an ongoing fashion?
The oxygen analyzer is the only machine safety device that evaluates the integrity of the low-pressure circuit in an ongoing fashion. It is the only machine monitor that can detect problems downstream from the flow control valves.
It is the only machine monitor that can detect problems downstream from the flow control valves.
Oxygen Analyzer
Which is the most important component of the scavenging system?
The scavenging interface is the most important component of the system because it protects the breathing circuit or ventilator from excessive positive or negative pressures.
The manual bag is about
3L
Thorpe tubes tapered where?
Tapered on top, height of the floating bobbin in the lumen indicates the current flow rate.
FLOW affected by ______With TURBULENTflow
DENSITY.
FLOW affected by ______With LAMINAR flow
VISCOSITY
FLUSH VALVE:why this pathway exists at all?
If the patient somehow become disconnected from the anesthesia breathing apparatus during controlled ventilation, the ventilator bellows , or the breathing bag, will immediately deflate as the volume of gas within will be drained into the operating room environment. The flush actuator could be used to rapidly increase the volume of gas in the system, so that normal tidal volumes may resume. This should be undertaken with care and advisably only during the expiratory phase of respiration when any excess gas or pressure resulting from the use of the flush valve can be scavenged away from the system (see “Scavenging Systems”
The effect of PROPORTIONING SYSTEM; set it up so that the ratio of nitrous oxide flow to Oxygen flow never
exceeds 3:1
What is VP
The pressure exerted against the wall of the container in this space by the gas-phase is called the vapor pressure( VP)
WHY ARE THEY CALLED VARIABLE BYPASS?
When not in use, the fresh gas flow of O2/Air/N20 BYPASSESS these vaporizers and continues onward to the patient. When the control dial of the anesthetic vaporizer is rotated COUTERCLOCKWISE, it diverts a portion of the carrier gas to the internal vaporizing channel , where it will incorporate a certain amount of anesthetic gas and then return to join the fresh gas flow where the mixture of anesthetic and oxygen will be delivered to the CGO.
If temperature drops in the OR
There will be a PREDICTABLE and PROPORTIONAL DECREASE in the VP of the agent, and LESS ANESTHETIC will be available in the gas state to be delivered to the patient
What is the role of the fresh gas outlet ?
which delivers the desired concentrations of gases and volatile anesthetics into the next conceptual framework (system) of the anesthesia machine: the anesthesia breathing apparatus
As a matter of perspective, using the flush valve to inflate a patient’s lungs
exposes the patient to roughly 200 Times the typical inflation pressure during routine MV
What is the oxygen fail-safe system purpose?
MINIMIZE the decrement in FiO2 by PROPORTIONALLY decreasing the flow of ALL OTHER GASES, in use or STOP their administration COMPLETELY, when a DECLINE IN OXYGEN pressure occurs. That prevents a disproportionate increase in the concentration of fresh gas that the patient is getting.
Boiling point, the temperature at
which both liquid and gas
Explain boiling point
As the temperature increases, more molecules enter the gas phase and the vapor pressure of the liquid increases.
At some point in time, as the temperature increases, the vapor pressure of the liquid will increase to the point where it equals the external or atmospheric pressure. At this point, bubbles begin to form and rise in the liquid and it is said to be boiling.
DESFLURANE, boiling point is CLOSE to that of
room temperature, therefore can be used in conventional variable bypass vaporizers
TEC-6 designed specifically for
DESFLURANE because of it LOW BOILING POINT
During mechanical ventilation , what reinflates the bag
expired gases
Remember the anesthesia machine is a
Circle system, if not for the absorbent, the patient will be rebreathing CO2 and have hypercarbia.
A very high Fresh gas flow will put the patient at risk for _______ why?
Barotrauma to the lungs (injury to the lung) ; because the vent automatic pressure relief valve is completely closed during inspiration.
When the fresh gas flow is high, what happens to the Expired TV?
Virtually all the expired TV would escape, through the scavenging system, creating a NRB circuits.
At the conclusion of surgery, doing what will help patient emerge from inhalational anesthesia
Using HIGH FLOW because there is not rebreathing
A patient normal oxygen consumption is about
300ml/min, increases if patient is hyper metabolic (fever)
If less than the required oxygen is provided , the rebreathing bag will
Collapse and the patient will be unable to breathe.
Nonfunctional unidirectional valve leads to
Expired gases to enter the inspiratory limb
During manual ventilation the APL valve is
Partially closed to allow sufficient tension to inflate the bag. THe provider can squeeze the bag and insuflflate the patient’s lung with an appropriate TV.
When the patient is breathing spontaneously the APL should be
open to allow the patient to breathe and discourage accumulation of pressure in the system.
The most commonly used analyzers uses
Galvanic cell analysis to measure oxygen.
Fresh gas flow decoupling is associated with ______machine and is
Newer machine. it designs to divorce the Fresh gas flow from the circle system during the inspiratory phase. As a result, the patient only receives the TV set by the user.
Why is fresh gas flow decoupling good?
it eliminates the risk of FGF induced volutrauma or barotrauma
FGF decoupling is bad
It uses the bag as a fresh gas reservoir and when the bag inadvertently becomes disconnnected, OR is exposed to anesthetic gas, room air can be entrained diluting the oxygen and gas concentration that the patient is set to receive.
What is the primary determinant of the amount of waste gas scavenged?
The FGF out of the CGO
At low flow, how much gas escape?
very low amount
At high FG flow, how much gas
Excess gas will vent through scavenging system.
2 ways to define a scavenging system?
Dynamic gas flow: Active or passive
Anatomic design: open or close.
In active system (scavenger)
Negative pressure is applied through hospital vacuum to facilitate removal of waste gas
In passive system (scavenger)
Passive systems rely simply on the small amount of positive pressure generated during exhalation to promote waste gas disposal.
Scavenging closed
Closed systems are self-explanatory: a system of hoses evacuates exhaled gas in a contained manner that prohibits the waste gas from entering the operating room.
Open systems contain vents in the scavenging reservoir that
do allow waste gas to potentially enter the operating room.
Why is an OPEN system that allow gases to the OR? Explain
Think about what might happen if the hose that sends waste gases out of the room becomes occluded. In a closed system, waste gas would accumulate, generating positive pressure that could theoretically be conveyed to the patient. The presence of vents in the scavenging reservoir in an open system, however, would allow this excess pressure to dissipate into the operating room
When the patient is breathing spontaneously on the vent, one reason for high AIRWAY pressure
Overexpansion of the rebreathing bag, open the APL to reduce pressure.
