Machine

Question 1

Functions of anesthesia machine

Answer 1

• Receives gases from central supply system or pressurized cylinders
• Controls the flow of desired gases & reduces their pressure
• Measures a precise amount of gases & loads them with anesthetic vapors
• Provides gas to patient for breathing
• Provides monitoring & safety features

Question 2

First anesthesia delivery system

Answer 2

Ether soaked rag over patient’s mouth & nose

Dr. Crawford Long - March 30, 1842

Question 3

Function of presure regulators

Answer 3

Reduces high & variable pressures in cylinders to intermediate pressure (45 PSIg)

Question 4

O₂ E Cylinder’s Volume & Pressure

Answer 4

Volume = 625L

Pressure = 2200 psig

Question 5

N₂O E Cylinder’s Volume & Pressure

Answer 5

Volume = 1590 L

Pressure = 725 psig

Question 6

Air E Cylinder Volume & Pressure

Answer 6

Volume = 625 L

Pressure = 2000 psi

Question 7

FiO₂ calculation

Answer 7

FiO₂ = O2 (L/min) + Air (L/min) (0.21)
Total Gas Flow (L/min)

• If O₂ = Air, then FiO₂ = 0.6

Question 8

Volatile agents’ MAC values

Answer 8

Iso = 1.2

Sevo = 1.7

Des = 6

Question 9

Circle system components

Answer 9

Fresh Gas Inlet

Unidirectional Valves

Inspiratory Limb

Expiratory Limb

Gas Reservoir Bag (green)

Adjustable Pressure-Limiting (APL) Valve - on expiratory limb

CO2 Absorber

Question 10

When and how to use the APL valve

Answer 10

• Number turned to is maximum pressure that can be generated in the circuit
• When this pressure is reached, the valve opens & excess gas is vented to the scavenging system during inspiration.
• During mechanical ventilation the APL valve is isolated from the breathing system.

Question 11

Basic Ventilations modes

Answer 11

Spontaneous
Patient is breathing on their own without assistance

Assisted
Augmentation of tidal volume with patient making some respiratory effort (use PSV mode, or manually squeezing reservoir bag as patient inspires)

Controlled
Total control of respiration with patient making no respiratory effort (squeezing bag during bag/mask, or using ventilator after intubation)

Question 12

How ascending bellows work

Answer 12

• Descends during inspiration
• Drive gas pushes bellows down
• Expired gas from patient pushes bellows up
• Collapses if breathing circuit becomes disconnected from the patient

Question 13

When to change CO₂ absorber

Answer 13

• CO2 in inspired gases**most reliable
• Color change - Color conversion of a pH indicator dye by increasing hydrogen ion concentration signals absorbent exhaustion. Absorbent should be replaced when 50–70% has changed color
• Heat in canisters - Changes in absorbent temperature occur earlier than changes in the color of the indicator

Question 14

What does noninterchangeable gas-specific connections to pipeline inlets (DISS) with pressure gauges, filter, and check valve do?

Answer 14

Prevent incorrect pipeline attachments; detect failure, depletion, or fluctuation

Question 15

What is the purpose of pin index safety system (PISS) for cylinders with pressure gauges, and at least one oxygen cylinder?

Answer 15

Prevent incorrect cylinder attachments; provide backup gas supply; detect depletion

Question 16

What is the purpose of low O2 pressure alarm?

Answer 16

Detect O2 supply failure at the common gas inlet

Question 17

What is the purpose of minimum O2/N2O ratio controller device (hypoxic guard)?

Answer 17

Prevent delivery of less than 21% O2

Question 18

What is the purpose of O2 failure safety device (shut-off or proportioning device)?

Answer 18

Prevent administration of N2O or other gases when the O2 supply fails

Question 19

Why must O2 enter the common manifold downstream to other gases?

Answer 19

Prevent hypoxia in event of proximal gas leak

Question 20

What is the purpose of O2 concentration monitor & alarm?

Answer 20

Prevent administration of hypoxic gas mixtures in event of a low-pressure system leak; precisely regulate O2 concentration

Question 21

What is the purpose of automatically enabled essential alarms and monitors (eg, oxygen concentration)?

Answer 21

Prevent use of the machine without essential monitors

Question 22

What is the purpose of the vaporizer interlock device?

Answer 22

Prevent simultaneous administration of more than one volatile agent

Question 23

What is the purpose of capnography & anesthetic gas measurement as far as safety is concerned?

Answer 23

Guide ventilation; prevent anesthetic overdose; help reduce awareness

Question 24

What is the purpose of O2 flush mechanism that does not pass through vaporizers?

Answer 24

Rapidly refill or flush the breathing circuit

Question 25

What is the purpose of breathing circuit pressure monitor & alarm?

Answer 25

Prevent pulmonary barotrauma & detect sustained positive, high peak, & negative airway pressures

Question 26

What is the safety purpose of exhaled volume monitor?

Answer 26

Assess ventilation and prevent hypo- or hyperventilation

Question 27

What is the safety purpose of the mechanical ventilator?

Answer 27

Control alveolar ventilation more accurately and during muscle paralysis for prolonged periods

Question 28

Anesthesia machine checkout

Answer 28

* Step 1 * Verify backup ventilation equipment (ie AMBU bag) * Step 2 * Check Oxygen cylinder supply * Step 3 * Check central pipeline supplies * Step 4 * Check initial status of low pressure system (everything OFF) * Step 5 * Perform leak check of low pressure system * Step 6 * Turn machine ON * Step 7 * Test flow meters * Step 8 * Adjust & check scavenging system * Step 9 * Calibrate O2 monitor (should go from 21% to \>90%) * Step 10 * Check initial status of breathing system (CO2 absorber, improperly attached circuit) * Step 11 * Perform breathing system leak check * Step 12 * Test ventilation systems & unidirectional valves * Step 13 * Check capnometer * Step 14 * Check final status of machine