Principles ofPrinciples of

Mechanical VentilationMechanical Ventilationin ICUin ICU

Raafat Abdel AzimRaafat Abdel Azim

TTT of the cause

ETI + MV

PEEP

O2

DrugsIVFV

Secretions

ECMO

ECCO2R

CFAV

Treatment of Respiratory Failure

NPPV

22

Oxygen SupplementationOxygen Supplementation

Aim: Aim: PPAAOO2 PaO PaO2 > 60 mmHg (60:100) > 60 mmHg (60:100) If < 60 If < 60 abrupt abrupt of saturation & content of saturation & content If > 100 If > 100 no more benefit no more benefit

Not > 50% > 24hNot > 50% > 24h Potential complication: OPotential complication: O2 PaCOPaCO2

33

Methods of OMethods of O22 Supplementation Supplementation

(O(O22 Devices) Devices)

100%

OO22

AIR

(21% OO22)

?% OO22

Flow Rate? Patient’s IFR?

44

OO22 Devices Classification Devices Classification

High O2

(up to 100%)Controlled O2

(set)%

Delivered O2 %

Flow Capacity

High Flow Low Flow

55

1.1. Nasal CannulaNasal Cannula

Low flow, low O2

OO22 Devices Devices

•Low flow 0.5 – 5 L/min

•Maximal tracheal FIO2 0.4 – 0.5

(cannot be precisely controlled, VE)FR No in FIO2

Drying and irritating effect

66

2.2. Air-Entrainment Face Masks Air-Entrainment Face Masks (Venturi Masks)(Venturi Masks)

OO22 Devices Devices

High flow, controlled O2

O2

Air

•High FR

•FIO2 precisely controlled (0.24 – 0.5)

by changing jet nozzle

adjusting FR•Most useful in COPD patients (titratable)

77

3.3. Aerosol Face MasksAerosol Face Masks

Moderate flow, variable O2

OO22 Devices Devices

•Large side holes, large bore tubing, a nebulizer

•Flow matching can be evaluated by observing the aerosol mist

88

4.4. Reservoir Face MasksReservoir Face Masks

High flow, high O2

OO22 Devices Devices

FR is adjusted so that the reservoir bag remains distended

99

5.5. Resuscitation Bag-Mask-Valve UnitResuscitation Bag-Mask-Valve Unit

OO22 Devices Devices

Mask held firmly over the face air entrainment

High flow > 15 L/min

Bag need not be compressed to supply O2

High flow, high O2

1010

ABGABG PaOPaO22??

SaOSaO22??

PaCOPaCO2 2 > 6 mmHg (in 30 min) = significant > 6 mmHg (in 30 min) = significant

retentionretention

1111

NPPVNPPV

NPPV ventilator

Nasal mask

Face mask

or or

Standard Ventilator

PS Volume cycled

Patient triggered

•Better tolerated

•Less effective in mouth breathers and edentulous patients

1212

NPPVNPPV

Not recommended unless the patient is:Not recommended unless the patient is: Alert, oriented & cooperativeAlert, oriented & cooperative Not having:Not having:

Swallowing dysfunctionSwallowing dysfunction Difficulty clearing secretionsDifficulty clearing secretions HypotensionHypotension Uncontrolled arrhythmiasUncontrolled arrhythmias Acute cardiac ischemiaAcute cardiac ischemia Acute GI hemorrhageAcute GI hemorrhage

1313

May not be desirable with:May not be desirable with: levels of ventilatory requirementslevels of ventilatory requirements

(( C requires C requires P) P) ability to adequately clear secretionsability to adequately clear secretions

(especially with face mask)(especially with face mask) Careful observation and monitoringCareful observation and monitoring Possible G distension & aspiration riskPossible G distension & aspiration risk

NPPVNPPV

1414

NPPVNPPVSettings

Specialized Unit Standard Ventilator

PS mode

8-12 cmH2O IPAP

AC mode10 ml/kgPEEP or EPAP

Titrate P, V & FIO2 PaO2 & PaCO2

1515

ETI and MVETI and MVETI when?ETI when?

PaOPaO2 2 < 60 (F< 60 (FIIOO22 >> 0.5) 0.5)

PaCOPaCO2 2 + + pHpH Respiratory muscle fatigueRespiratory muscle fatigue Loss of protective upper airway reflexesLoss of protective upper airway reflexes Ineffective cough + Ineffective cough + secretionssecretions Level of consciousnessLevel of consciousness

1616

Seconds%I:E

Time

I E

Mode

MVO2 in air

How?

Volume

f

VT

% (FIO2)

PEEPOthers

Alarms & LimitsWave form

FlowTrig. sensitivity 1717

Mechanism of action of the ventilator (Mode of operation):

4 phases

Inspiratory phase

Expiratory phase

Cycling from I to ECycling from E to I

1818

Two phases: I & ETwo phase transitions:

From I to E = expiratory cyclingBetween E and I = inspiratory cycling

Inspiration can itself sometimes have two phases: an active ‘flow’ (TI flow) phase during which gas is being delivered to the patientan end-inspiratory pause (TI pause )The total duration of inspiration is made of the sum of these two:

TI = TI flow + TI pause

Respiratory cycle

1919

2020

Intra-thoracic pressures

2121

Pressure gradients within the thorax

Distending pressures

2222

Control of Parameters of Ventilation

• VT

• f (frequency= rate)

• VM

• I:E ratio

• Flow Rate

• Flow Profile

• Trigger Sensitivity

2323

IFR (Inspiratory Flow Rate)IFR (Inspiratory Flow Rate)VT (ml)f (b/min)Cycle time

(s)IFRTI (s)TE (s)I:E

L/minL/sml/s

5002060/20 = 360110000.52.51:5

300.5500121:2

Time (sec)

0.500

100

200

300

400

500

600

1.5 2.5 3.5 4.5 5.51 2 3 4 5 6

60 L/min30 L/min

2424

Inspiratory WaveformsInspiratory Waveforms

30

30

60

60

0

Constant Decelerating Accelerating (ramp)

Sinusoidal (reverse ramp)

TI TI TI TI

2525

The Ventilation Cycle

2626

Paw

0 t

PmaxPplat

IF E

ZEEP

IPPV

20

I EP

ause2727

• Duration of ventilation cycle (sec)

• f (60/duration)

• I phase (IF period, IP period)

• E phase

• VT, VM

• TI, TE, I:E

FVPT2828

Inspiratory Phase

During the IF period:Paw depends on:

• The airway resistance (R)

• The total thoracic compliance (C) (V/P)

RC2929

PP PP

P

P

P

PP

PP

P

P

P

Resistance

Flow Rate: FRP3030

Paw

0 t

20

N R F R F

Resistance

3131

Calculation of Airway Resistance (Raw) in a Ventilated Patient

Raw = (PIP – Pplat) / Flow

Example: If in a given situation,PIP = 40 cm H2O,Pplat = 38 cm H2O,flow = 60 L/min (i.e., 1 L/s),Raw will be:= (40 − 38)/1= 2 cm H2O/L/s.

3232

Compliance

C

C

P PVolume

3333

PVolume: VP

P

Compliance

3434

During I pause

• No gas F into or out of the lungs Paw depends only on VI & CT

• Gas redistributes among alveoli

• This improves gas distribution in the lungs of patients with small AWD (BA, smokers).

Pause

3535

Paw

0 t

20

C R

Secretions

Bronchospasm

Kinked ETT

EB intubation

CW rigidity

Pulmonary edema

3636

Compliance = V/P

Dynamic compliance:

= VT/(PIP-PEEP) L/cmH2O Static compliance:

= VT/(Pplat-PEEP) L/cmH2O

3737

Time Constants of the LungTime Constants of the LungIn most diseases, the involvement of the lung is not uniform. Regional differences in C and R occur. Owing to this, alveoli in different parts of the lung behave differently; diseased alveoli take longer to fill and to empty.

The rate of filling of an individual lung unit is referred to as its time constant.

For a particular lung unit

Time Constant = R x C3838

It takes the equivalent of 5 time constants for the lung to completely fill (or to empty).

In the time afforded by one time constant, 63% of the lung will fill (or empty); two time constants allow 86% of the inspiratory or expiratory phase to be completed; three time constants allow for 95%, and four time constants for 98%.

63 86 95 98 10012

34

5

3939

Example:

A lung unit with a normal Raw of 1 cm H2O/L/sand a normal compliance of 0.1 L/cm H2O would have a time constant of:

= 1 × 0.1= 0.1 s

Five times this is 0.5 s, which would be the time required for this unit to fill or empty satisfactorily. This information comes useful while setting a ventilator’s TI and TESince diseased air units take longer to fill, deliberatelyprolonging the TI may enable such units to participatemore meaningfully in gas exchange

4040

Goals of Mechanical Ventilation

4141

Provide appropriate O2 supplementation

Assure adequate alveolar VM

work of breathing (WOB)

patient comfort during respiration

4242

• To provide adequate minute alveolar ventilation

• and to side effects

necessary to maintain the desired PaCO2

PPV ITP

4343

Adequate Ventilation

• PaCO2 of 40 mmHg = 5.3% of 760 mmHg40/760 = 0.053

• Normal resting VCO2= 200 ml/min= 0.2 L/min• This requires VM of 3.8 L

0.2/ ? = 0.0530.2/ 0.053 =

• Add dead space (VD)

Goals

3.8 L/min

4444

• N = 2.2 ml/Kg (1 ml/pound) 150 ml in a 70 Kg (154 pound) adult• = 0.15 x 10 (f) =• Required VM = 3.8 + 1.5 =

• A larger VM is required for patients who have VD or VCO2

1.5 L/min

5.3 L

Goals, Adequate Ventilation

For VCO2 For VD

VD phys = VD ana + VD alvVD ana = conducting airways = 150 ml in a 70 Kg adultVD alv is created when non-perfused alveoli are ventilated (negligible in health, expands in disease)This 150 ml of VD ana is reduced by ETT and can be cut down to about 60% by tracheostomy

4545

• When VCO2 & VD are stable:

VM 1/ PaCO2

VM x PaCO2 = constant

• e.g., PaCO2 = 50 mmHg with VM = 5 L/min

VM to 7 L/min PaCO2 to 36 mmHg

Goals, Adequate Ventilation

V1 x P1aCO2 = V2 x P2aCO2

4646

VM =VT x f

Manipulation of VT has a different effect on the PaCO2 than does altering f.

Consider the following:A set VT of 500 ml and f of 10 b/min results in a VM of 500 × 10 = 5,000 ml/min. The same VM can be produced by a VT of 250 ml delivered at f of 20 b/min, i.e., 250 × 20 = 5,000 ml/min. If, however, the VD is taken into consideration, the implications of these two settings are vastly different.Assuming a VD phys of 150 ml, the alveolar ventilation (the effective ventilation or the ventilation that takes part in gas exchange) in the first example would be:

(500 – 150) × 10 = 3,500,and in the second example would be:

(250 – 150) × 20 = 2,000.

PaCO2 is inversely proportional not to all of the VM, but to that part of the ventilation that is independent of VD (i.e., the alveolar ventilation VA)

4747

Side effects

Goals

ITP

VR

EDV

CO

PVR RVAPPV

4848

Goals, Side Effects

PPV

ITP PA > PAP VVD

4949

All these effects mean Paw

Therefore, a goal of PPV is to mean Paw while maintaining adequate ventilation and oxygenation

Goals

5050

Effect of IFR on mean Paw

Mean Paw = area under the curve

5151

Modes (examples)Modes (examples)

Volume controlled Volume controlled IPPV (CMV)IPPV (CMV)

Pressure controlled Pressure controlled (PCV) (PLV)(PCV) (PLV)

IRVIRV

CPAPCPAP AA ACAC IMVIMV SIMVSIMV PSVPSV BIPAPBIPAP APRVAPRV Other modesOther modes

Breathing support

5252

Volume Controlled Ventilation Volume Controlled Ventilation (Controlled Mode Ventilation) (CMV) (IPPV)(Controlled Mode Ventilation) (CMV) (IPPV) Initial settings:Initial settings:

ff 10-12 /min10-12 /min VVTT 8-10 ml/Kg 8-10 ml/Kg FFIIOO22 11 I:EI:E 1:2 (1:3 in COPD)1:2 (1:3 in COPD)

AimAim pHpH 7.36 : 7.447.36 : 7.44 PaOPaO22 60: 100 mmHg60: 100 mmHg PaCOPaCO22 36: 44 mmHg36: 44 mmHg

Adjust settings (ABG, SpOAdjust settings (ABG, SpO22 > 92-94%) > 92-94%)5353

IPPVIPPV Preset f & VPreset f & VTT

No patient interaction with ventilatorNo patient interaction with ventilator Advantage: rests muscles of respirationAdvantage: rests muscles of respiration Disadvantages: requires sedation/NMB, Disadvantages: requires sedation/NMB,

potential adverse hemodynamic effects, potential adverse hemodynamic effects, muscle atrophymuscle atrophy

5454

Paw

0 t

PmaxPplat

IF E

ZEEP

IPPV

20

I EP

ause5555

Inspiratory Plateau Pressure (PInspiratory Plateau Pressure (Pplatplat))

PPawaw at end of I with no gas flow present at end of I with no gas flow present

It estimates PIt estimates PA A at end Iat end I Indirect indicator of alveolar distensionIndirect indicator of alveolar distension

5656

I:E RatioI:E Ratio

Spontaneous breathing I:E = 1:2Spontaneous breathing I:E = 1:2 TTII determinants with preset V breaths: determinants with preset V breaths:

VVTT

GFRGFR ff I pauseI pause

TTEE passively determined passively determined

5757

I:E RatioI:E Ratio

TTEE too short for exhalation too short for exhalation Breath stackingBreath stacking Auto-PEEPAuto-PEEP

Auto-PEEP by Auto-PEEP by T TII

GFRGFR VVTT

ff

5858

During the expiratory phaseDuring the expiratory phase

VT

FRC

FRC

EI

FRCIA contents•Pulmonary edema•ARDS

PEEPPaO2 PaO2

5959

Paw

0 t

PEEP

IPPV + PEEP

6060

PEEPPEEP

PEEP, When?PEEP, When?PaOPaO22 < 60 mmHg (FIO < 60 mmHg (FIO22 >> 0.5) 0.5)

ActionAction

Expansion of collapsed perfused alveoliExpansion of collapsed perfused alveoli PaOPaO22

CCLL

FRCFRC Prevention of absorption atelectasisPrevention of absorption atelectasis

Improvement of V/Q QS/QT

6161

PEEP, HowPEEP, How??2.5-5 cmH2.5-5 cmH22O O incrementsincrements until PaO until PaO22 > 60 > 60

(FIO(FIO22 << 0.5) 0.5)

Goal:Goal: PEEP with maximum improvement of PaOPEEP with maximum improvement of PaO2 2

without hazardswithout hazards HazardsHazards

• COP (VR, PVR, left septal displacement)• Barotrauma (Pnx, Pnp, SC emphysema) abrupt PaO2 & COP

PEEPPEEP

6262

Best PEEP

Best PEEP

O2 transport

Static CL

Don’t give PEEP > 15 cmH2OHow to avoid COP

IVFVInotropicsPA catheter

PEEPPEEP

6363

Paw

0Sigh phase

Pmax

Int PEEP

PEEP

Intermittent PEEP(Expiratory Sigh)

t

6464

Auto-PEEPAuto-PEEP Can be measured on some ventilatorsCan be measured on some ventilators peak, plateau, and mean Pawpeak, plateau, and mean Paw Potential harmful physiologic effectsPotential harmful physiologic effects

PEEPPEEP

6565

Paw

t

Pressure-limited ventilation (PLV) (PCV)

Pmax

Pplat

0

6666

PCVPCV

Used to limit inflationary pressuresUsed to limit inflationary pressures Allows setting of TAllows setting of TII

Complexity of interacting ventilatory variablesComplexity of interacting ventilatory variables

6767

Paw

0

20

t I E

Inverse Ratio Ventilation (IRV)

Improves oxygenationNeonatesARDS

Alveolar recruitment by creating auto PEEP

No advantage over 1:1 (+PEEP) at f < 15

IRVHypoxemic RF

Optimize PEEP

FIO2 requirements > 0.6 or SaO2 < 90%

Consider IRV

VC- IRV PC- IRV

IFR I pause I:E with decelerating flows

Most effective

Indications of IRVIndications of IRV

ARDS with severe hypoxemic RF (especially ARDS with severe hypoxemic RF (especially with with FIOFIO22 requirements and PEEP) requirements and PEEP)

No uniformly accepted criteria. Proposed No uniformly accepted criteria. Proposed criteria:criteria: VC-IRV:VC-IRV:

FIOFIO22 > 0.6 or PEEP >10 cmH > 0.6 or PEEP >10 cmH22O to maintain SaOO to maintain SaO22

>90%>90% PC-IRV:PC-IRV:

Above parameters + PIP Above parameters + PIP >> 45 cmH 45 cmH22OO7070

Point of Reference:Spontaneous Breathing (SB)

Breathing Support

7171

Paw

0 t

SB

-ve

+ve

7272

Paw

0 t

CPAP

CPAP

7373

CPAP No machine breaths delivered Allows SB at elevated baseline P

Patient controls f & VT

7474

Assisted Ventilation (A)Paw

0

A

t

S

Patient f and timingHazard: hypoventilation

If or No S

No A

7575

Paw

0

A+CProvides a minimum f below which C

Assist-Control (AC)

7676

AC

Preset VPreset VTT & minimal f & minimal f

Additional patient-initiated breaths receive preset VAdditional patient-initiated breaths receive preset VTT

Advantages: Advantages: WOB; allows pt. to modify V WOB; allows pt. to modify VM

Disadvantages: potential adverse hemodynamic Disadvantages: potential adverse hemodynamic effects or inappropriate hyperventilationeffects or inappropriate hyperventilation

Preferred initial mode in most situations

7777

IMV

0

Paw

St

Preset VT and f

SB is allowedMuscle atrophy is less likely

IMV PaCOPaCO2 < apneic threshold no SB IMV = IPPV

7878

Indications of IMVIndications of IMV

Drug overdoseDrug overdose Intermittent heavy sedationIntermittent heavy sedation Unstable ventilatory driveUnstable ventilatory drive Weaning (may be combined with PSV)Weaning (may be combined with PSV)

7979

Paw

0 tTriggering

window

Mandatory

S

Synch. Mandatory

NO

Preset VT and fSIMV

8080

SIMV•Preset VT at a preset f

•Additional SBs at VT & f determined by patient

•Often used with PSV

•Indications:•1ry means of MV if adequate VE is delivered

•Severe respiratory alkalosis•To prevent auto PEEP•Weaning

SIMV

Potential advantagesPotential advantages Better patient-ventilator interactionBetter patient-ventilator interaction Less hemodynamic effectsLess hemodynamic effects

Potential disadvantages Potential disadvantages Higher WOB > CMV, ACHigher WOB > CMV, AC

8282

Pressure Support Ventilation (PSV)(Inspiratory Pressure Support = IPS)

(Assisted Spontaneous Breathing = ASB)

0

Paw

Spont.

PSV

Trig. Sensitivity

t

8383

Paw

0

CPAP

t

PSV

8484

PSV Pressure assist during SB (= ASB)Pressure assist during SB (= ASB) P assist continues until inspiratory effort P assist continues until inspiratory effort Delivered Delivered VVTT dependent on I effort & R/C of dependent on I effort & R/C of

lung/thoraxlung/thorax

8585

PSV

Potential advantagesPotential advantages Patient comfort Patient comfort WOB < SBWOB < SB May enhance patient-ventilator synchronyMay enhance patient-ventilator synchrony Used with SIMV to support SBUsed with SIMV to support SB

Indications:Indications: Stable patients receiving long-term MV (Stable patients receiving long-term MV (WOB)WOB) WeaningWeaning

8686

PSV

Potential disadvantages

–Variable VT if pulmonary R/C changes rapidly

–If sole mode of ventilation, apnea alarm is only backup

–Gas leak from circuit may interfere with cycling

8787

Paw

0 t

CPAP

Apnea alarm

15 s

IPPV

Apnea time

15-60 s

Apnea Ventilation

8888

Paw

0 t

Biphasic Intermittent Positive Airway Pressure

BIPAP (PCV+)

Spont.

Spont.

PCV

P1

P2

T high T low

P & T can be independently set

8989

SB superimposed on standard PCV

9090

PCV: closed

BIPAP: controlled

E valve

9191

Auto Flow

Auto flow Auto flow application of the "open application of the "open breathing system" even to Volume Controlled breathing system" even to Volume Controlled ventilation modesventilation modes

Can be used + any Volume oriented mode like Can be used + any Volume oriented mode like IPPVIPPV SIMVSIMV MMVMMV

BIPAP

9292

CPAP

SIMV-BIPAP

IPPV-BIPAP

Genuine BIPAP

No SB

SB only at P level

Continuous SB at 2 P levels

Continuous SB, both P levels are equal

Mode Contribution of SB

9393

SB possible at all times (open breathing system) Patient comfort

Patient is never locked out No fighting against the ventilator Can cough and clear his airways at any time

Sedation/MR required Improved SB Proph. & ttt of atelectasis No barotrauma or CVS Full ventilatory support, No switching between Full ventilatory support, No switching between

modes is requiredmodes is required

BIPAP

9494

Airway Pressure Release Ventilation (APRV)

P high PAO2

P low CO2

SB on 2 CPAP levels

E

MV is achieved by MV is achieved by instead of instead of Paw Paw If no SB, APRV = PC-IRVIf no SB, APRV = PC-IRV Barotrauma (Barotrauma ( Pp Pp –– Pmean) Pmean) CVSCVS Indications: (not clear)Indications: (not clear)

Mild ALIMild ALI Alveolar hypoventilation states with minimal Alveolar hypoventilation states with minimal

airflow obstructionairflow obstruction

APRV

9696

Bilevel Positive Airway Pressure (BiPAP) System

A home care device PSV to augment patient ventilation

A non-invasive alternative to traditional management in non life support applications

2 levels of PP

PCycling between the 2 levels is in response to patient F

If the patient fails to initiate P change a timed phase9797

Useful in (home care):Useful in (home care): Obstructive sleep apneaObstructive sleep apnea COPDCOPD Musculoskeletal disordersMusculoskeletal disorders

BiPAP

9898

BIPAP = PCV + SB at all timesBIPAP = PCV + SB at all times APRV = similar + extended times at higher PsAPRV = similar + extended times at higher Ps BiPAP system = a non continuous form of BiPAP system = a non continuous form of

breathing support breathing support

9999

Advantages of different modesCMVCMVRests muscles of respirationRests muscles of respiration

ACACPatient determines amount of ventilatory supportPatient determines amount of ventilatory supportWOBWOB

SIMVSIMVImproved patient-ventilator interactionImproved patient-ventilator interactionInterference with normal CV functionInterference with normal CV function

PSVPSVPatient comfortPatient comfortImproved patient-ventilator interactionImproved patient-ventilator interactionWOBWOB

PCVPCVAllows limitation of PIPAllows limitation of PIPControl of I:EControl of I:E

100100

Disadvantages of different modesCMVCMVNo patient-ventilator interactionNo patient-ventilator interaction

Requires sedation/NMBRequires sedation/NMBMuscle atrophyMuscle atrophyPotential adverse hemodynamic effectsPotential adverse hemodynamic effects

ACACPotential adverse hemodynamic effectsPotential adverse hemodynamic effectsMay lead to inappropriate hyperventilationMay lead to inappropriate hyperventilation

SIMVSIMVWOB compared to ACWOB compared to AC

PSVPSVApnea alarm is only backupApnea alarm is only backupVariable effect on patient toleranceVariable effect on patient tolerance

PCVPCVPotential hyper- or hypoventilation with R/C Potential hyper- or hypoventilation with R/C changeschanges

High Frequency Ventilation (HFV) What is it? What is it? VVT T (1-3 ml/kg)(1-3 ml/kg) , , ff Types:Types:

Applied to chest wall:Applied to chest wall:

HF body surface oscillationsHF body surface oscillations Applied at air openings:Applied at air openings:

HFPPVHFPPV 60-110 b/min60-110 b/min (60-100)(60-100) HFJVHFJV 110-400 b/min110-400 b/min (100-600)(100-600) HFOHFO 400-2400 b/min400-2400 b/min (300-3000)(300-3000)

102102

AdvantagesAdvantages:: Raw and CRaw and CLL don don’’t affect efficacy of t affect efficacy of

ventilationventilation Paw Paw no no COP, no barotrauma COP, no barotrauma Reflex suppression of SB Reflex suppression of SB no need for no need for

sedatives/MRsedatives/MR

HFV

103103

IndicationsIndications BP fistulaBP fistula Bronchoscopy, upper AW proceduresBronchoscopy, upper AW procedures ARDSARDS Patients at Patients at risk for barotrauma (stiff L + risk for barotrauma (stiff L + Paw)Paw) Patients who cannot be intubatedPatients who cannot be intubated ICPICP ShockShock Thoracic surgery (e.g., descending A. Aneurysm)Thoracic surgery (e.g., descending A. Aneurysm) LithotripsyLithotripsy

HFV

104104

Permissive Hypercapnia

Acceptance of Acceptance of Pa PaCOCO22, e.g., , e.g., V VTT to to peak peak

PawPaw

Contraindicated with Contraindicated with ICP ICP

Consider in severe asthma and ARDS Consider in severe asthma and ARDS

105105

Pediatric Considerations

Infants (< 5 kg)

–Time-cycled, PLV

–PIP initiated at 18–20 cm H2O

–Adjust to adequate chest movement or exhaled VT 10–15 mL/kg

–Low level of PEEP (2–4 cm H2O) to prevent alveolar collapse

106106

ChildrenChildren SIMV modeSIMV mode VVTT 10 mL/kg 10 mL/kg

Flow rate adjusted to yield desired TFlow rate adjusted to yield desired TII

Infants 0.6Infants 0.6––0.7 secs0.7 secs Toddlers 0.8 secsToddlers 0.8 secs Older 0.9Older 0.9––1.0 secs1.0 secs

f <18-20 /minf <18-20 /min PEEP 2-4 cm HPEEP 2-4 cm H22OO 107107

108108