Basic Of Mechanical Ventilation

1. The Basics of VentilatorsThe Basics of Ventilators
Richard M. Ford BS RRTRichard M. Ford BS RRT
UCSD Respiratory CareUCSD Respiratory Care

2. Why Important ?Why Important ?
äManaging the Patient/Ventilator Managing the Patient/Ventilator
system is less difficult with an system is less difficult with an
understanding of the understanding of the
fundamentals of operation, fundamentals of operation,
alarms, and capabilities.alarms, and capabilities.

3. Where to Start ?Where to Start ?
ASV, APRV, AutoFlow, AutoMode, AutoPEEP,
BiLevel, BiPAP, Closed Loop, CPAP, Control
Variables, Demand Flow, Differential Output,
Duty Time, EPAP, Flow Control Valves, Fluid
Logic, HFJV, HFOV, HFFI, HFPV, IPAP, Linear
Drive Piston, Mandatory Breath, MAP, MMV,
NEEP, PEEP, PIP, Phase Variables, Pplateau,
PCV, PCIRV, PRVS, PRVC, PSV, PV, Proportional
Amplifier, PAV, Rotary Drive Piston, Static
Compliance, SIMV, Threshold Resistor, Total
Cycle Time, Trigger Variable, Variable Pressure
Control, VCIRV, Volume Support, WOB…
from SP Pilbeam, Respiratory Care Equipment, Mosby

4. Beyond Basic-Beyond Basic-
Today's TechnologyToday's Technology
äBMTI - Bird and BearBMTI - Bird and Bear
äDrager Medical TechnologiesDrager Medical Technologies
äHamilton MedicalHamilton Medical
äMallinckrodt IncMallinckrodt Inc
äNewport NMINewport NMI
äPulmoneticPulmonetic
äSiemensSiemens

5. From the ManufacturersFrom the Manufacturers
äSmart Breath Delivery, Dual View, San
Box, Smart Alert, Interactive Automode,
Advanced Rules Based Strategic Modes,
Virtual Controls
äGUI Interface, soft keys, configurable
äSafety, upgradability, portability

6. Objectives Objectives
äUnderstand how ventilators Understand how ventilators
control breath delivery - phase, control breath delivery - phase,
type and control variables.type and control variables.
äUnderstand the basic adjuncts Understand the basic adjuncts
and modes of ventilation. and modes of ventilation.

7. Basic Ventilator ParametersBasic Ventilator Parameters
äFiOFiO
22
åFractional Fractional
concentration of concentration of
inspired oxygen inspired oxygen
delivered expressed as delivered expressed as
a % (21-100)a % (21-100)
äBreath Rate (f)Breath Rate (f)
åThe number of times The number of times
over a one minute over a one minute
period inspiration is period inspiration is
initiated (bpm)initiated (bpm)
äTidal volume (VTidal volume (V
TT))
åThe amount of gas The amount of gas
that is delivered during that is delivered during
inspiration expressed inspiration expressed
in mls or Liters. in mls or Liters.
Inspired or exhaled.Inspired or exhaled.
äFlowFlow
åThe velocity of gas The velocity of gas
flow or volume of gas flow or volume of gas
per minute per minute

8. Phase VariablesPhase Variables
äTrigger (start)- begins inspiratory flowTrigger (start)- begins inspiratory flow
äCycling (end)- ends inspiratory flowCycling (end)- ends inspiratory flow
äLimiting (continue)- places a maximum Limiting (continue)- places a maximum
value on a “control variable”value on a “control variable”
åpressurepressure
åvolumevolume
åflowflow
åtimetime

9. Breath Type… Only Two (for now)!Breath Type… Only Two (for now)!
äMandatoryMandatory
åVentilator does the workVentilator does the work
åVentilator controls start and stopVentilator controls start and stop
äSpontaneousSpontaneous
åPatient takes on workPatient takes on work
åPatient controls start and stopPatient controls start and stop

10. Trigger Variable- Trigger Variable-
Start of a BreathStart of a Breath
äTime - Time - control ventilationcontrol ventilation
äPressure - Pressure - patient assistedpatient assisted
äFlow - Flow - patient assistedpatient assisted
äVolume - Volume - patient assistedpatient assisted
äManual - Manual - operator controloperator control
äImpedance - Impedance - patient assistedpatient assisted

11. The Control Variable-The Control Variable-
Inspiratory Breath DeliveryInspiratory Breath Delivery
äFlow (volume) controlledFlow (volume) controlled
åpressure may varypressure may vary
äPressure controlledPressure controlled
åflow and volume may varyflow and volume may vary
äTime controlled (HFOV)Time controlled (HFOV)
åpressure, flow, volume may varypressure, flow, volume may vary

12. If compliance decreases the pressure increases to
maintain the same Vt
Volume Control Breath TypesVolume Control Breath Types
11 22 33 44 55 66
SECSEC
11 22 33 44 55 66
PPawaw
cmHcmH
2200
6060
-20-20
120120
120120
SECSEC
INSPINSP
EXHEXH
FlowFlow
L/minL/min

13. Many Dual Modes start out looking like PCV
A New Twist…A New Twist…
Volume TargetedVolume Targeted
1 2 3 4 5 6
SEC
1 2 3 4 5 6
Paw
cmH
20
60
-20
120
120
SEC
INSP
EXH
Flow
L/min

14. Volume TargetedVolume Targeted
(Pressure Controlled)(Pressure Controlled)
As compliance changes - flow and volumes change
1 2 3 4 5 6
SEC
1 2 3 4 5 6
Paw
cmH
20
60
-20
120
120
SEC
INSP
EXH
Flow
L/min

15. Pressure then raises to assure that the set tidal
volume is delivered
New Volume Targeted Breath New Volume Targeted Breath
Pressure Variability is ControlledPressure Variability is Controlled
1 2 3 4 5 6
SEC
1 2 3 4 5 6
Paw
cmH
20
60
-20
120
120
SEC
INSP
EXH
Flow
L/min

16. Inspiratory - delivery limitsInspiratory - delivery limits
äMaximum value that can be Maximum value that can be
reached but will not end the reached but will not end the
breath-breath-
åVolumeVolume
åFlowFlow
åPressurePressure

17. End of Insp…cycle mechanismsEnd of Insp…cycle mechanisms
äThe phase variable used to The phase variable used to
terminate inspiration-terminate inspiration-
åVolumeVolume
åPressurePressure
åFlowFlow
åTimeTime

18. Expiratory - baselineExpiratory - baseline
äPPositive ositive EEnd nd EExpiratory xpiratory PPressureressure
äExpiratory RetardExpiratory Retard
äNNegative egative EEnd nd EExpiratory xpiratory PPressureressure
äExpiratory HoldExpiratory Hold
äTime Limited Exhalation (APRV)Time Limited Exhalation (APRV)

19. PEEPPEEP
äDefinitionDefinition
åPositive end expiratory pressurePositive end expiratory pressure
åApplication of a constant, positive pressure such that Application of a constant, positive pressure such that
at end exhalation, airway pressure does not return to at end exhalation, airway pressure does not return to
a 0 baselinea 0 baseline
äUsed with other mechanical ventilation modes Used with other mechanical ventilation modes
such as A/C, SIMV, or PCVsuch as A/C, SIMV, or PCV
äReferred to as CPAP when applied to Referred to as CPAP when applied to
spontaneous breathsspontaneous breaths

20. PEEPPEEP
äIncreases functional residual capacity Increases functional residual capacity
(FRC) and improves oxygenation(FRC) and improves oxygenation
åRecruits collapsed alveoliRecruits collapsed alveoli
åSplints and distends patent alveoliSplints and distends patent alveoli
åRedistributes lung fluid from alveoli to Redistributes lung fluid from alveoli to
perivascular spaceperivascular space
5 cm 5 cm
HH
22OO
PEEPPEEP

21. CPAPCPAP
äDefinitionDefinition
åContinuous positive airway pressureContinuous positive airway pressure
åApplication of constant positive pressure Application of constant positive pressure
throughout the spontaneous ventilatory cyclethroughout the spontaneous ventilatory cycle
äNo mechanical inspiratory assistance is No mechanical inspiratory assistance is
provided provided
åRequires active spontaneous respiratory driveRequires active spontaneous respiratory drive
äSame physiologic effects as PEEPSame physiologic effects as PEEP

22. CPAPCPAP
äMay decrease WOBMay decrease WOB
äTidal volume and rate determined by patientTidal volume and rate determined by patient
äOften final form of support before extubationOften final form of support before extubation
10 cm 10 cm
HH
22O O

PEEPPEEP
TimeTime

23. Basic Modes of VentilationBasic Modes of Ventilation
äControl Control
äAssist, Assist/ControlAssist, Assist/Control
ä(S)IMV(S)IMV
äPCVPCV
äPSVPSV
äServo Servo

24. ControlControl
äDelivery of a Delivery of a
mandatory mandatory
breath at a set breath at a set
time interval - time interval -
time is the time is the
trigger to start trigger to start
the breaththe breath
F
P

25. Safety Issue - Control Safety Issue - Control
äControl mode should never be Control mode should never be
deliberately set as the ventilator deliberately set as the ventilator
should never be insensitive to a should never be insensitive to a
patients inspiratory effortspatients inspiratory efforts
äControl ventilation is a patient driven Control ventilation is a patient driven
function and new ventilators do not function and new ventilators do not
even incorporate a pure “control” even incorporate a pure “control”
functionfunction

26. Assist, Assist ControlAssist, Assist Control
äPatient is Patient is
able to able to
trigger the trigger the
start of start of
inspirationinspiration
F
P

27. Safety Issue - Assist ControlSafety Issue - Assist Control
äThe control rate must be set high The control rate must be set high
enough to insure that minute enough to insure that minute
ventilation will be adequateventilation will be adequate
äApnea ventilation will also serve as a Apnea ventilation will also serve as a
back up back up
äAs rate increases expiratory time will As rate increases expiratory time will
shorten and gas trapping may occurshorten and gas trapping may occur

28. Synchronize Intermittent Synchronize Intermittent
Mandatory Ventilation - SIMVMandatory Ventilation - SIMV
äA minimum A minimum
mandatory breath mandatory breath
rate is set with rate is set with
spontaneous spontaneous
breathing supported breathing supported
between the between the
mandatory cyclesmandatory cycles
F
P

29. SIMVSIMV
äAdvantagesAdvantages
åSynchronized breaths may Synchronized breaths may
improve patient comfortimprove patient comfort
åIncrease patient control/regulationIncrease patient control/regulation
åEnhances blood flowEnhances blood flow
åHyperventilation less of a concern Hyperventilation less of a concern
compared to A/Ccompared to A/C

30. Volume vs…Volume vs…
Pressure Control Ventilation Pressure Control Ventilation
Volume VentilationVolume Ventilation
äVolume delivery Volume delivery
constantconstant
äInspiratory pressure Inspiratory pressure
variesvaries
äInspiratory flow Inspiratory flow
constantconstant
äInspiratory time Inspiratory time
determined by set flow determined by set flow
and Vand V
TT
PressurePressure VentilationVentilation
äVolume delivery varies Volume delivery varies
äInspiratory pressure Inspiratory pressure
constantconstant
äInspiratory flow variesInspiratory flow varies
äInspiratory time set by Inspiratory time set by
clinicianclinician

31. Pressure Control Ventilation - Pressure Control Ventilation -
PCVPCV
äThe ventilator The ventilator
delivers a set delivers a set
pressure limit pressure limit
over a set over a set
inspiratory timeinspiratory time
F
P

32. Pressure Control Ventilation - Pressure Control Ventilation -
PCV, with Inverse Ratio IRVPCV, with Inverse Ratio IRV
äThe ventilator The ventilator
delivers a set delivers a set
pressure limit over pressure limit over
a set inspiratory a set inspiratory
time, however time, however
inspiration is longer inspiration is longer
than expirationthan expiration
F
P

33. Pressure Control VentilationPressure Control Ventilation
äAdvantagesAdvantages
åLimits risk of barotraumaLimits risk of barotrauma
åMay recruit collapsed alveoliMay recruit collapsed alveoli
åImproved gas distributionImproved gas distribution
äDisadvantagesDisadvantages
åTidal volumes vary when patient compliance Tidal volumes vary when patient compliance
changes (i.e. ARDS, pulmonary edema)changes (i.e. ARDS, pulmonary edema)
åWith increases in I-time, patient may require With increases in I-time, patient may require
sedation and/or paralysis sedation and/or paralysis

34. Pressure Support Ventilation - Pressure Support Ventilation -
PSVPSV
äThe ventilator The ventilator
delivers a set delivers a set
pressure limit pressure limit
with end with end
inspiration inspiration
driven by the driven by the
patientpatient
F
P

35. Safety Issue - PSVSafety Issue - PSV
äPSV is a spontaneous mode of PSV is a spontaneous mode of
ventilation, therefore the patient ventilation, therefore the patient
must demonstrate they can trigger must demonstrate they can trigger
the ventilator and that volumes are the ventilator and that volumes are
appropriateappropriate
äHigh and low rate, apnea, and high High and low rate, apnea, and high
and low tidal volume alarms need to and low tidal volume alarms need to
be assessedbe assessed

36. Bi LevelBi Level
äIs a spontaneous Is a spontaneous
breathing mode breathing mode
in which two in which two
levels of levels of
pressure and pressure and
hi/low are sethi/low are set
F
P

37. What is BiLevel Ventilation?What is BiLevel Ventilation?
äEnabled utilizing an active exhalation valveEnabled utilizing an active exhalation valve
äSubstantial improvements for spontaneous Substantial improvements for spontaneous
breathingbreathing
åbetter synchronization, more options for supporting better synchronization, more options for supporting
spontaneous breathing, and potential for improved spontaneous breathing, and potential for improved
monitoringmonitoring
Spontaneous Breaths
P
T
Spontaneous Breaths
Synchronized Transitions

38. What is BiLevel Ventilation?What is BiLevel Ventilation?
äAt either pressure level the patient can breathe At either pressure level the patient can breathe
spontaneouslyspontaneously
åspontaneous breaths may be supported by PS spontaneous breaths may be supported by PS
åif PS is set higher than PEEPif PS is set higher than PEEP
HH, PS supports , PS supports
spontaneous breath at upper pressure spontaneous breath at upper pressure
TT
PEEPPEEP
High High + PS + PS
PP
PEEPPEEP
LL
PEEPPEEP
HH
Pressure SupportPressure Support

39. Bi Level -APRV Bi Level -APRV
Airway Pressure ReleaseAirway Pressure Release
äIs a Bi-level form of Is a Bi-level form of
ventilation with ventilation with
sudden short sudden short
releases in pressure releases in pressure
to rapidly reduce to rapidly reduce
FRC and allow for FRC and allow for
ventilationventilation
äCan work in Can work in
spontaneous or spontaneous or
apneic patientsapneic patients
F
P

40. Then What Is APRV?Then What Is APRV?
äAPRV is similar but utilizes a very short expiratory time for APRV is similar but utilizes a very short expiratory time for
PRESSURE RELEASEPRESSURE RELEASE
åthis short time at low pressure allows for ventilationthis short time at low pressure allows for ventilation
äAPRV always implies an inverse I:E ratioAPRV always implies an inverse I:E ratio
äAll spontaneous breathing is done at upper pressure levelAll spontaneous breathing is done at upper pressure level
Spontaneous Spontaneous
BreathsBreaths
PP
TT
““ReleaseRelease
” ”

41. Safety Issue - IRV and APRVSafety Issue - IRV and APRV
äPronged inspiratory times with Pronged inspiratory times with
pressure transmission to the pressure transmission to the
surrounding chest structures may surrounding chest structures may
significantly reduced cardiac outputsignificantly reduced cardiac output
äDecrease in expiratory time may Decrease in expiratory time may
result in intrinsic PEEP which must be result in intrinsic PEEP which must be
consideredconsidered

42. Safety Issues - AlarmsSafety Issues - Alarms
äAlarms must be re-assessed with Alarms must be re-assessed with
every primary ventilator changeevery primary ventilator change
äAlarm silence should only be used Alarm silence should only be used
when the alarm condition is clear and when the alarm condition is clear and
attended toattended to
äThe most important back up is a The most important back up is a
skilled clinician with a resuc bagskilled clinician with a resuc bag

43. Potential Complications of MVPotential Complications of MV
äVentilator malfunctionVentilator malfunction
åManually ventilate patientManually ventilate patient
äBarotraumaBarotrauma
åAlveolar rupture due to overdistentionAlveolar rupture due to overdistention
åMonitor PIP, breath sounds PulmonaryMonitor PIP, breath sounds Pulmonary
äOxygen toxicityOxygen toxicity
ågoal: FIOgoal: FIO
22 << .50 and PaO .50 and PaO
22 >> 70 70
äCardiovascular compromise/arrhythmiasCardiovascular compromise/arrhythmias
åMonitor vital signsMonitor vital signs

44. Potential Complications of MVPotential Complications of MV
äInfectionInfection
åET tube bypasses natural airway defense mechanismsET tube bypasses natural airway defense mechanisms
–Nosocomial pneumonia, aspiration pneumoniaNosocomial pneumonia, aspiration pneumonia
åGood handwashing, provide mouth and tube careGood handwashing, provide mouth and tube care
äPsychologicalPsychological
åPatients may be extremely anxious and/or agitatedPatients may be extremely anxious and/or agitated
åGive consistent, calming explanations, offer reassuranceGive consistent, calming explanations, offer reassurance
åSedation, anti-anxiety agents frequently indicatedSedation, anti-anxiety agents frequently indicated

45. From Basics to Advanced...From Basics to Advanced...
äMicroprocessor controlled/GUI’sMicroprocessor controlled/GUI’s
äProportional solenoid control of gas delivery Proportional solenoid control of gas delivery
äNew exhalation valve technologyNew exhalation valve technology
äFast response times - low work of breathingFast response times - low work of breathing
äAbility to compensate for leaks/ET tubesAbility to compensate for leaks/ET tubes
äBroaden performance with pediatric and/or Broaden performance with pediatric and/or
infant capabilitiesinfant capabilities
äNew smart breathing algorithms/modes that New smart breathing algorithms/modes that
automatically adjust to changing patient automatically adjust to changing patient
conditionsconditions

46. Servo Regulated ModesServo Regulated Modes
äMandatory Minute Ventilation Mandatory Minute Ventilation
äPressure Regulated Volume ControlPressure Regulated Volume Control
äVolume SupportVolume Support
äAutoFlowAutoFlow
äProportional Assist VentilationProportional Assist Ventilation
äAdaptive Support VentilationAdaptive Support Ventilation
äVolume Assured Pressure SupportVolume Assured Pressure Support
äProportional Pressure SupportProportional Pressure Support