Sept 26, 2009Ashley Meister

 

 

1

Objectives Case set up Compare cases for set up Positions, effects on patient, risks Fluid replacement, scavenging Suction Ventilator set up

2

Patient Positioning Indications, precautions, complications and procedure for each of the following

patient positions: Supine Prone Lithotomy Beach chair Lateral decubitus Supine/ fracture table

3

General Concepts in positioningsedated/ anesthetized patients should not be

placed in positions they are not comfortable in when they are awake

Compromise between what patient can tolerate structurally and physiologically, and what is required for surgical access

Physiologic instability may be magnified by rapidly moving seriously ill patients

4

PositioningBony prominences can produce ischemic

necrosis of overlying tissue unless proper padding is required

Enhanced by hypothermia and hypotensionCaution particularly with ulnar nerve

5

Supine

Lying horizontallyArm pressure points padded and either tucked to side

or abductedAbduct less than 90 degreesExtend hands ventrally Ensure perfusion to the hand, no skin to metal contact

and no stretch on brachial neurovascular bundleNo compression in the axillaBony contacts at occiput, elbows & heals padded

6

SupineHorizontal supine, minimal changes to

vascular systemIf tipped into trendelenburg or reverse

trendelenburg, effects of gravity on blood flow significant.

Pressures change 2mmHg for each 2.5cm above or below level of the heart

7

SupineReverse trendelenburgBlood pools in legs, decreasing effective circulating volumeDecreased cardiac outputDecreased systemic perfusionPerfusion pressure in brain correspondingly decreased

compared to if measured at level of the heartVentilation dynamics are enhanced

8

SupineTrendelenburgIncreased pressure in cerebral veinsCan increase ICPCongestion around eyes and airwayNegative impact on ventilation

9

SupineRespiratory “Zones of West” shift Diaphragm is pushed cephalad Decreased FRC

10

SupinePregnant uterus rests on great vessels of the

abdomenAortocaval compression- therefore tilt into

Left lateral decubitus position/ left uterine displacement

11

SupineExcessive flexion or extension of the spine in

anesthetized patients who are placed in unique surgical positions may contribute to spinal cord ischemia and catastrophic neurological damage

12

13

Considerations with Prone positioning?

14

Prone Venous pooling in legs, decreased preload and decreased

cardiac output

If pressure is on abdominal viscera, transmitted to veins in spinal canal, causes increased bleeding in spine procedures

Extensive spine procedures in the prone position is associated with post operative visual loss (associated with blood loss, anemia & hypotension)

15

ProneImportance of secure airwayAlways have stretcher outside room in case

airway is lostCongestion of face and airwayCheck eyes & ears carefullyEnsure arms not extended > 90 degrees, and

well padded

16

What would you do?A/W is lost when prone

Key point- prevention

17

1

18

LithotomyGynecologic and urologic proceduresSupine, arms crossed on trunk or extended

laterally on arm boardsFlex lower extremities at hip and kneeBoth limbs simultaneously elevated and

separatedNerve injury possible if hips flexed greater

than 90 degrees

19

LithotomyEnsure padding over lower extremities if

pressure points existCan get hypotension if legs lowered quickly

or decreased effective circulating blood volume

Decreases diaphragmatic excursion and impairs ventilation

Caution with hands and watch BP when leveling table back to neutral

20

LithotomyElevated lower extremity positions may

reduce perfusion pressure in the elevated extremities

conditions for developing compartment syndromes, especially when extremities are elevated for prolonged periods

Maintain perfusion pressure to extremities

21

22

Beach ChairOften intubated as access to airway is

difficultEnsure ETT well secured and stays in place

while moving patient and bedCaution with elevating head of table with

venous pooling and hypotensionCase reports with decreased cerebral

perfusion

23

Lateral DecubitusTurned onto one side(left side down = left lateral decubitus

position)Place an axillary roll just under chest to take

pressure off axillary neurovascular bundleV/Q mismatch may occur, particularly with

co-existing pulmonary diseaseCaution with pressure to eyes & ears

24

25

Fracture TableFor repair of fractured femurPelvis is retained in place by a vertical pole at

perineum with the foot of the injured extremity fixed to a mobile rest

Traction is applied between the foot and pelvis

Perineal crush injury possible

26

Setting up the caseAssist with surgical draping, while

maintaining the integrity of the sterile fieldAvoid walking between or crossing over

sterile fields

27

Setting up the casePrepare, in consultation with the

anaesthesiologist, medication needs for general and regional anesthesia

28

Emergency DrugsSelection and preparation of medications, checked and

labelled for usage as appropriateFor every case:Succinylcholine 20 mg/ml 10mL syringeAtropine 0.4mg/ml- 0.6 mg/ml vials, 1mL syringeEphedrine 5mg/ml (50mg vial/ 10cc)Phenylephrine 100mcg/ml (10mg/100cc)

29

Equipment to PrepareLocal Sedation RegionalNeuraxial – spinal/ epidural/ CSEGeneral

30

CAS monitors Required: Pulse oximeter Apparatus to measure blood pressure, either directly or

noninvasively Electrocardiography Capnography, when endotracheal tubes or laryngeal masks are

inserted. Agent-specific anesthetic gas monitor, when inhalation

anesthetic agents are used.

31

CAS monitorsExclusively available for each patient: Apparatus to measure temperature Peripheral nerve stimulator, when

neuromuscular blocking drugs are used Stethoscope - either precordial, esophageal

or paratracheal Appropriate lighting to visualize an exposed

portion of the patient.

32

CAS monitorsImmediately available: Spirometer for measurement of tidal volume.

33

Preparation for Local/ standbyStandard CAS standard monitors in useAnesthesia available to provide sedationLocal anesthetic as per surgeon (watch

doses)Have emergency drugs available

34

Preparation for Sedation

CAS monitorsEmergency drugs available, IV, oxygenUseful to monitor capnographyMany drugs can be used to provide sedationMidazolamFentanylRemifentanilKetamine

35

Preparation for Regional CAS monitors Emergency Drugs available, iv, oxygen Again, variety of drugs may be used Midazolam Fentanyl ketamine Titrate to effect

36

Preparation for RegionalNeuromuscular stimulator, electrodes - ultrasound

availableSurface electrode - dressing if catheter Skin prep - local anesthetic for

skin Local anesthetic for skin infiltration - glovesLocal anesthetic for nerve block Nerve stimulating needle for block

37

Regional Setup

38

Preparing for Spinal/EpiduralCAS monitors, iv, oxygen may be requiredEmergency drugs available -

skin prepPrepackaged trays - traysLocal anesthetic/ opiod for injection - local

anestheticReady to assist with patient positioning

39

Preparing for General Anesthesia CAS monitors iv fluids Machine checked Other lines as necessary Emergency drugs ready ( Drugs for case ready ) Any other lines, procedures, equipment ready if anticipated

40

Preparing for General Anesthesia SuctionOxygen LaryngoscopeETTStyletConsider Airway and location of A/W backup

equipment

41

How to manage emergenciesAnaphylaxis

42

Emergency Situation- AnaphylaxisABC’sFluid resuscitationLarge bore iv access availableEpinephrine titrated to response start at 10 mcg, escalate dose as required, 50-100mcg if hypotensive, 1mg ACLS dose

43

Emergency Situation- AnaphylaxisH1 blocker Benadryl 50mgCorticosteroid Hydrocortisone 50-100mgStop inciting allergen exposure

44

How to manage emergenciesCardiovascular collapse

45

Emergency Situations- Cardiovascular EventsABC’sACLS protocolsResponses dictated by clinical scenarioCrash cart availableEnsure CPR started

46

How to manage emergenciesIncreased ICP

47

Emergency Situations- Increased ICP

Head of bed 30 degrees elevatedEnsure adequate cerebral venous drainageGeneral goals:Avoid hypoxemiaAvoid hypotension/ maintain cerebral perfusion CPP= MAP - ICPAvoid abrupt hypertension

48

Emergency Situations- Increased ICPPharmacologic measures to lower ICPModerate hyperventilation pCO2 30-35,

(short term)Mannitol 0.5-1g/kg through 50 micron filterLasix 0.5mg/kg

49

How to manage emergenciesMalignant Hyperthermia

50

How to manage emergenciesMalignant hyperthermiaHypermetabolic disorder of skeletal muscle Intracellular hypercalcemia in muscle activates

metabolic pathwaysEnergy depletion, acidosis, membrane destruction, cell

deathHeritable component, not invariably present by family

historyHallmark- hypercarbia, tachycardia, tachypnea,

hyperthermia, rigidity, arrhythmias, hyperkalemia, renal failure, DIC, death

51

Emergency Situations- Malignant Hyperthermia ABC’s Ensure MH crisis issued - MH cartStop triggering agents - hyperventilate,

100% O2, Finish case ASAP high flowsDantrolene 2.5mg/kg, repeat q5min prn until

10mg/kg (20mg mix with 60ml sterile H2O

52

Emergency Situations- Malignant HyperthermiaArterial line- blood work and blood gassesBegin cooling patientTreat supportivelyPatient will need ongoing treatment in ICU

53

Determine case requirements for suction; such as: Airway suction Gastric suction Thoracic suction Surgical suction Post-surgical wound drainage

54

SuctionAirwayHave suction ready as part of any inductionAttached to bronchoscopy portGastricBowel obstructions- low intermittent suction

55

Cell SaverCell saverIntraoperative blood salvageAnticoagulate salvaged blood as it leaves the

surgical fieldSeparates rbc’s from other components and

debrisWashes the rbc’s for return to patient

56

Cell SaverUseful for procedures with anticipated

significant blood lossReduce the use of autologous rbc transfusionContraindications:infection - malignant cellsContamination with urine, bowel contents,

amniotic fluid

57

Cell saverComplicationsDilutional coagulopathyReinfusion of contaminants- fat, leukocytes,

red blood cell stroma, air, free hemoglobin, heparin, bacteria, debris from surgical field

58

The Anesthesia Machine

59

High Intermediate

Low Pressure Circuit

Anesthesia Workstation

High pressure circuitCylinders including N2O, O2 & AirO2 2200psi -> 50 psiN20 750 psi -> 50 psiDecreased through pressure regulators

60

High Pressure SystemReceives gasses from the high

pressure E cylinders attached to the back of the anesthesia machine (2200 psig for O2, 745 psig for N2O)

Consists of:Hanger Yolk (reserve gas cylinder

holder)Check valve (prevent reverse flow of

gas)Cylinder Pressure Indicator (Gauge)Pressure Reducing Device (Regulator)

Usually not used, unless pipeline gas supply is off6161

61

E Size Compressed Gas CylindersCylinder Cylinder CharacteristicCharacteristicss

OxygeOxygenn

Nitrous Nitrous OxideOxide

Carbon Carbon DioxideDioxide

AirAir

ColorColor White White (green)(green)

BlueBlue GrayGray Black/Black/White White (yellow)(yellow)

StateState GasGas Liquid and Liquid and gasgas

Liquid and Liquid and gasgas

GasGas

Contents (L)Contents (L) 625625 15901590 15901590 625625

Empty Weight Empty Weight (kg)(kg)

5.905.90 5.905.90 5.905.90 5.905.90

Full Weight Full Weight (kg)(kg)

6.766.76 8.808.80 8.908.90

Pressure Full Pressure Full (psig)(psig)

20002000 750750 838838 1800180062

Example ½ full E cylinder, 30 L gas, at 10 L/min, approximately 30 min of oxygen available

Hanger Yolk orients and supports

the cylinder, providing a gas-tight seal and ensuring a unidirectional gas flow into the machine

Index pins: Pin Index Safety System (PISS) is gas specific prevents accidental rearrangement of cylinders (e.g.. switching O2 and N2O)

63

Anesthesia WorkstationIntermediate pressure circuit

Includes pipeline O2 and N20 at 50-55psiExtends to flow control valves

64

Intermediate Pressure SystemReceives gasses from the

regulator or the hospital pipeline at pressures of 40-55 psig

Consists of: Pipeline inlet connections Pipeline pressure indicators Piping Gas power outlet Master switch Oxygen pressure failure

devices Oxygen flush Additional reducing devices Flow control valves

65

Pipeline Inlet ConnectionsN2O and O2, usually have

air and suction tooInlets are non-

interchangeable due to specific threading as per the Diameter Index Safety System (DISS)

Each inlet must contain a check valve to prevent reverse flow (similar to the cylinder yolk)

66

Low Pressure SystemExtends from the flow control valves to the

common gas outletConsists of:

Flow metersVaporizer mounting deviceCheck valveCommon gas outlet

67

Anesthesia Workstation

Cylinder supply source is back-up if pipeline supply fails

Fail-safe valve located downstream from N2O supply sources

Interface between O2 & N20 with proportioning system

Prevent delivery of hypoxic gas mixtures

68

Anesthesia WorkstationHigh priority alarm- if O2 supply pressure is less than a

critical pressure (<30psi)Regulated flow enters low pressure circuit with

adjustments in flowmetersGas mixture travels through a common manifold directed to

vaporizerPrecise amounts of inhaled anesthetics added, controlled

by dial flow

69

Anesthesia WorkstationFresh gas flow with added anesthetic vapor travel to

common gas outletDatex-Ohmeda have one-way check valves between

vaporizer and common gas outletPrevent back flow into the vaporizer during PPVMinimize effects of downstream intermittent pressure

fluctuations on inhaled anesthetic concentrationsOne-way check valve influences preoperative leak test

70

Pipeline Supply SourceCritical errors have occurred if incorrect

supply attached to machinesPipeline inlet fittings are gas specific with

threaded fittingsDiameter Index Safety System (DISS)If pipeline crossover suspected: turn on

back-up O2 cylinder Pipeline supply must then be disconnected

71

Cylinder Supply SourceE cylindersPin Index Safety SystemPressure reducing valve downstreamIf not turned off, will be preferentially usedVolume of gas remaining in the cylinder is

proportional to cylinder pressure

72

Oxygen supply pressure failure safety deviceDesigned to not allow hypoxic mixture

deliveryAlarm sounds if oxygen pressure fallsO2 linked with delivery of other gasses to be

oxygen dependentIf O2 pressure falls, other gas delivery falls

73

FlowmetersIndicator float position is where upward force

from gas flow equals downward force on float from gravity

O2 flow knob physically different from other gas knobs

N2O and O2 interfaced mechanically/ pneumatically, maximum 3:1 ratio

Oxygen flowmeter located downstream from other flowmeters in case of a leak

74

Limitations of Proportioning SystemsMachines equipped with proportioning

systems can still deliver a hypoxic mixture under the following conditions: Wrong supply gas Defective pneumatics or mechanics (e.g.. The Link-25

depends on a properly functioning second stage regulator) Leak downstream (e.g.. Broken oxygen flow tube) Inert gas administration: Proportioning systems generally

link only N2O and O2In general, an oxygen analyzer is the only

machine safety device that can detect these problems (gas sampling done at the Y-piece of the patient circuit)

75

Oxygen Flush ValveDirect communication with high pressure and

low pressure circuitEnters circuit downstream from vaporizers

and from machine outlet check valve100% O2 at 35-75 L/min (50 psi)Potential problems: barotrauma, decreasing

volatile anesthetic concentration, awareness

76

Oxygen Flush Valve (O2+)Receives O2 from pipeline

inlet or cylinder reducing device and directs high, unmetered flow directly to the common gas outlet (downstream of the vaporizer)

Machine standard requires that the flow be between 35 and 75 L/min

The ability to provide jet ventilation via the O2 flush valve is presence of a check valve between the vaporizer and the O2 flush valve (otherwise some flow would be wasted retrograde)

77

Vaporizers Instrument designed to change a liquid anesthetic agent

into its vapor and add a controlled amount of this vapor to the fresh gas flow

Important that each volatile anesthetic is in type specific vaporizer

Physical properties of volatile anesthetics If incorrectly filled with inappropriate anesthetic, resulting

output drastically changes

78

VaporizersVariable bypass- regulating anesthetic agent

outputConcentration control dial determines ratio

of flow through the bypass chamber and enters the vaporizer inlet

Gas channeled through the vaporizing chamber flows over the liquid anesthetic and becomes saturated with vapor

Flow over- method of vaporization

79

VaporizersTemperature compensated- maintains a

constant vaporizer output over a wide range of operating temperatures

Agent specificIf vaporizer is overfilled or tilted, liquid

anesthetic can spill into the bypass chamberFinal concentration of inhaled anesthetic is

the ratio of the flow of the inhaled anesthetic to the total gas flow

80

Generic Bypass VaporizerFlow from the

flowmeters enters the inlet of the vaporizer

The function of the concentration control valve is to regulate the amount of flow through the bypass and vaporizing chambers

Splitting Ratio = flow though vaporizing chamber/flow through

bypass chamber

Examples include the Tec 3, Tec 4, Tec 5 and the Drager 19.1

81

Vaporizers- safety featuresAgent- specific, keyed filling devicesOverfilling minimized because the filler port

is located at the maximum safe liquid levelFirmly secured to a vaporizer manifoldInterlock system to prevent administration of

>1 anesthetic agent

82

Desflurane’s Tec 6 VaporizerBecause of physical properties of Desflurane, supplying it

in a conventional vaporizer would lead to excessive cooling of the vaporizer

Vapor pressure is much higher than other volatile anesthetics

Much less potent (higher MAC)Would vaporize many more volumes of Desflurane than

other agentsTec 6 electrically heated and vaporized

83

Tec-6 VaporizerElectronically heated

and pressurized to achieve controlled vaporization of desflurane

2 independent circuits (fresh gas and vaporizer)

Vaporizer output is controlled by adjusting the concentration control valve (R2)

Pressure in the two limbs is equalized by the pressure regulating valve

84

Desflurane’s Tec 6 VaporizerEssentially a dual gas blenderBy controlling the dial, the operator controls

a variable restrictor valve

85

The Circuit: Circle SystemSo-called because the

components are arranged in a circular manner

Arrangement is variable, but to prevent re-breathing of CO2, the following rules must be followed: Unidirectional valves

between the patient and the reservoir bag

Fresh-gas-flow cannot enter the circuit between the expiratory valve and the patient

Adjustable pressure-limiting valve (APL) cannot be located between the patient and the inspiratory valve

86

Circle Breathing System Prevents rebreathing of CO2 by use of CO2 absorbents

Allows partial rebreathing of other exhaled gasses Components: Fresh gas inflow source - CO2 absorbent Inspiratory and expiratory unidirectional valves - reservoir

bag Adjustable Pressure Limiting (APL) valve - Y-piece

connector

87

Circle Breathing SystemUnidirectional flow Maintenance of relatively stabile inspired gas

concentrationsConservation of respiratory moisture and

heatPrevention of OR pollutionDisadvantage is- many possible sites for

misconnections and leaks

88

The Adjustable Pressure Limiting (APL) Valve User adjustable valve that releases

gases to the scavenging system and is intended to provide control of the pressure in the breathing system

Increased pressure in the breathing system (from patient) pushes the diaphragm off its seat venting the excess gas into the scavenging system

The control knob controls the position of the diaphragm

Bag-mask Ventilation: Valve is usually left partially open. During inspiration the bag is squeezed pushing gas into the inspiratory limb until the pressure relief is reached, opening the APL valve. At this point the additional volume the patient receives is determined by the relative resistances to flow exerted by the patient and the APL valve

Mechanical Ventilation: The APL valve is excluded from the circuit when the selector switch is changed from manual to automatic ventilation

89

CO2 absorber2 clear plastic canisters arranged in seriesSoda lime, Baralyme and calcium hydroxide limeSoda lime- calcium hydroxide, water, sodium hydroxide and

potassium hydroxide, silicaCO2 + H2O <-> H2CO3H2CO3 + 2NaOH (KOH) <-> Na2CO3 (K2CO3)+2H20 +

heatNa2CO3 (K2CO3) + Ca(OH)2 <->CaCO3 +2NaOH (KOH)

90

CO2 AbsorberpH indicator added to assess absorbentChanges to violet color when pH of the

absorbent decreases as a result of CO2 absorption

Indicates absorptive capacity of material has been consumed

91

Scavenging System Collection and subsequent removal of waste anesthetic gases

from the operating room Minimizes OR pollution by removing excess gasses National Institute for Occupational Safety and Health (NIOSH)

standards 2ppm for halogenated agent alone 25 ppm for N2O Halogenated with N20 0.5 ppm

92

Scavenging Systems Scavenging Interface:

Protects the breathing circuit or ventilator from excessive positive or negative pressure. There are 2 kinds of scavenging interfaces: Open: Contains no valves and is

open to the atmosphere allowing both positive and negative pressure relief

Closed: Communicates with the atmosphere through valves

Gas Disposal Assembly: This assembly ultimately eliminates the waste gas. There are 2 kinds of gas disposal assemblies: Passive: Uses the pressure of

the waste gas itself to produce flow through the system

Active: Uses a central vacuum to induce flow in the system, moving the waste gas along. A negative pressure relief valve is mandatory (in addition to positive pressure relief) 93

Scavenging System

Adds to OR pollution:Failure to turn off gas flow at end of casePoorly fitting masks, flushing the circuitFilling vaporizersOther circuit types which are difficult to

scavenge

94

Scavenging SystemActive or passiveActive- uses central evacuation system to

eliminate waste gasesPassive- pressure of waste gas itself produces

flowWaste anesthetic gases are vented through

the APL valve or through the ventilator relief valve

95

Scavenging SystemPotential problems:Obstruction- excessive positive pressure in

the breathing circuit and barotraumaExcessive vacuum- negative pressures within

the breathing circuit

96

Generic Ascending Bellows VentilatorBellows physically separates

the driving gas circuit from the patient gas circuit

During the inspiratory phase the driving gas enters the bellow chamber resulting in: Compression of bellows

delivering the anesthetic gases within the bellows to the patient

Closure of the overflow valve, preventing anesthetic gas from escaping into the scavenging system

During the expiratory phase the driving gas exits the bellows chamber. Exhaled gas fills the bellows Excess gas opens the

overflow valve (PEEP of 2-3 cmH2O) allowing scavenging of excess gases to occur

97

Machine CheckAnesthesia Apparatus Checkout Recommendations,

FDA. 1993. Categories of check:

• Emergency ventilation equipment - high pressure system

• Low-Pressure system - low pressure system

• Scavenging system - breathing system

• Monitors - final position

• Manual and automatic ventilation system

• Final Position

98

Checking Anesthesia Machines

99

Preoperative Checklist- High Pressure SystemCheck O2 cylinder supply -open cylinder and verify at least ½ full

-close cylinderCheck central Pipeline Supplies

- check connections and pipeline gages

100

Preoperative Checklist- Low Pressure SystemCheck initial status of low pressure system

- close flow control valves and turn vaporizers off - check fill level and tighten vaporizer’s filler cap

• Perform Leak Check - machine master switch and flow control valves OFF - attach suction bulb to common gas outlet - squeeze bulb until fully collapsed - verify bulb fully collapsed > 10 seconds - check same for each vaporizer

101

Low Pressure Circuit Leak TestChecks the integrity of the anesthesia machine from the

flow control valves to the common outlet (e.g. leaks at flow tubes, O-rings, vaporizer)

Two types of leak test (depending on presence or absence of check valve) Oxygen Flush Positive-Pressure Leak Test: Only used in machines

without check valves; basically just pressurize the low pressure circuit using the O2+ flush valve and look for leak

Negative Pressure Leak Test: Used in machines with or without check valves (i.e. Ohmeda). Attach suction bulb to common gas outlet, squeeze repeatedly until fully collapsed and ensure that it remains collapsed for 10 seconds. Will detect leaks as small as 30 ml/min.

102

Preoperative Checklist- Low Pressure SystemTurn on Machine Master SwitchTest flowmeters - adjust flow off all gasses checking for

smooth operation of floats and undamaged flow tubes

- attempt to create a hypoxic N2O/O2 mixture and verify correct changes in flow

103

Preoperative Checklist- Scavenging SystemAdjust and check scavenging system - ensure proper connections between

scavenging system and APL valve and ventilator relief valve

- adjust waste gas vacuum - fully open APL valve and occlude Y-piece

104

Preoperative Checklist- Scavenging System - with minimum flow, allow scavenger

reservoir bag to collapse completely and verify that absorber pressure gauge reads zero

- with O2 flush activated, allow scavenger reservoir bag to distend full, and verify that absorber pressure gauge reads <10 cm H2O

105

Preoperative Checklist- Breathing System Calibrate O2 monitor - ensure monitor reads 21% on room air

- verify low O2 alarm is enabled and functioning

- reinstall sensor in circuit and flush breathing system with O2

- verify that monitor now reads > 90%

106

Preoperative Checklist- Breathing SystemCheck Initial Status of Breathing System

- set switch to “bag” mode- check that circuit is complete,

undamaged and unobstructed- verify that CO2 absorbent is adequate- install breathing circuit accessory

equipment to be used during case (HME)

107

Preoperative Checklist- Breathing System Perform Leak Check of the Breathing System

- Set all gas flows to zero- Close APL valve and occlude Y-piece- Pressurize breathing system to 30 cmH2O

with O2 flush- Ensure that pressure remains fixed >

10seconds- Open APL valve and ensure pressure

decreases

108

Preoperative Checklist- Manual and Automatic Ventilation Systems Test Ventilation systems and unidirectional valves

-place a second breathing bag on Y-piece-switch on automatic ventilation-turn ventilator on and fill bellows and breathing

bag with O2 flush-set O2 flow to minimum, other gasses off

109

Preoperative Checklist- Manual and Automatic Ventilation Systems

- verify that during inspiration bellows deliver appropriate TV and that during expiration bellows fill completely

- set fresh gas flow to approximately 5 L/min

-Verify ventilator bellows and simulated lungs fill and empty appropriately without sustained pressure and end expiration

-Check for proper functioning of unidirectional valves

110

Preoperative Checklist- Manual and Automatic Ventilation Systems

-switch to bag/APL mode- Ventilate manually and assure

inflation and deflation of artificial lungs and appropriate feel of system resistance and compliance

- Remove second breathing bag from Y-piece

111

Preoperative Checklist- MonitorsCheck, calibrate and/or set alarm limits of all

monitors- Capnometry- O2 analyzer- Pressure monitor with high and low

A/W pressure alarms- Pulse oximeter- Respiratory volume monitor

112

Preoperative Checklist- Final Position of MachineCheck final status of machine

- vaporizers off - APL valve open

- selector switch to “bag”- all flowmeters to zero/minimum- patient suction level adequate- breathing system ready to use

113

Oxygen Analyzer Calibrationonly machine safety device that evaluates the

integrity of the the low-pressure circuit continuously

Other machine safety devices are upstream from flow control valves

Expose O2 concentration sensing element to room air for calibration to 21%

114

The Virtual Anesthesia Machinehttp://vam.anest.ufl.edu/

115