mechanical ventilation for dummies

Mechanical Ventilation for DummiesKeep It Simple Stupid• Indications

– Airway– Ventilation failure

(CO2)– Hypoxia– Combination

• Airway obstruction• Inability to protect

airway• Hypoxia (PaO2 < 50)• Hypercapnia (PaCO2

> 50)• Respiratory distress

(RR > 30, use of accessory muscles)

Ventilator ManagementScalar

• CMV• ACV• IMV• SIMV• SIMV + PS• PCV• IRV• PRVC• APRV• CPAP Essentials of Ventilator Graphics ©2000 RespiMedu

Control Mode- Scalars(Volume- Targeted Ventilation)Control Mode- Scalars

(Volume- Targeted Ventilation)

P r e s s u r eP r e s s u r e

V o l u m eV o l u m e

F l o wF l o wPreset Peak FlowPreset Peak Flow

Preset Preset VVtt

Dependent onDependent onCCLL & R& Rawaw

T im e (s e c )T im e (s e c )

(L/min)(L/min)

(cm H(cm H22O)O)

(ml)(ml)

Essentials of Ventilator Graphics ©2000 RespiMedu

Control Mode- Scalars(Volume- Targeted Ventilation)Control Mode- Scalars

(Volume- Targeted Ventilation)

P r e s s u r eP r e s s u r e

V o l u m eV o l u m e

F l o wF l o wPreset Peak FlowPreset Peak Flow

Preset Preset VVtt

Dependent onDependent onCCLL & R& Rawaw

T im e (s e c )T im e (s e c )

(L/min)(L/min)

(cm H(cm H22O)O)

(ml)(ml)

CLINICAL UTILITY OF VENTILATOR GRAPHICSVijay Deshpande, MS, RRT, FAARC

Ventilator ManagementLoops


Pressure-Volume LoopsPressure-Volume Loops

Volume Volume ((mLmL))

Insp

iratio

n

Insp

iratio

n

Expi

ratio

n

Expi

ratio

n

PIPPIP

VVTT

PPawaw (cm H(cm H22O)O)


Pressure-Volume LoopsPressure-Volume Loops

Volume Volume ((mLmL))

Insp

iratio

n

Insp

iratio

n

Expi

ratio

n

Expi

ratio

n

PIPPIP

VVTT



Flow-Volume LoopFlow-Volume Loop

Volume (ml)Volume (ml)

1

2

34

InspirationInspiration

ExpirationExpiration

Flow Flow (L/min)(L/min)

FRC


Flow-Volume LoopFlow-Volume Loop

Volume (ml)Volume (ml)

1

2

34



Flow Flow (L/min)(L/min)

FRC


Ventilator ManagementThis really is all there is to it

• Time (RR)• Volume (Vt)• Pressure (PIP, Pplat)• Flow

Volume vs Time ScalarVolume vs Time Scalar



Time (sec)Time (sec)

Volume Volume (ml)(ml)

Inspiratory Tidal VolumeInspiratory Tidal Volume

TITI

Volume vs Time ScalarVolume vs Time Scalar




Volume Volume (ml)(ml)

Inspiratory Tidal VolumeInspiratory Tidal Volume

TITI

Ventilator ManagementControl Mechanical Ventilation• Time – Set respiratory rate• Volume – Set Vt• Flow – Set to deliver the Vt• Airway Pressure – Dependent on the

interaction of the above and on the respiratory system compliance and airflow resistance

} Independent Variables

Ventilator ManagementPressure Control Ventilation

• Time – Set respiratory rate• Pressure – Set pressure• Flow – Set to deliver pressure• Volume – Dependent on the interaction of

the above and on the respiratory system compliance and airflow resistance


Ventilator ManagementDual Control Modes - PRVC• Time – Set RR• Volume – Set VT

• Flow – Set• Pressure –increases or decreases to

maintain the set VT (Dependent variable), but this is Limited (i.e. controlled)


Airway Pressure Release Ventilation APRV-BILEVEL

SIMV

CPAP is transiently decreased or “released” to a lower level during expiration.

Advantages1. Lower Paw for a given VT2. Lower VE, i.e., less dead space3. Limited adverse effects on cardiac function4. Spontaneous breathing5. Decreased sedationPotential Disadvantages1. Volumes change with changes in compliance and resistance2. New technology3. Limited access to technology4. Limited research and clinical experience

Ventilator Management

• Peak Insp Pressure (PIP) vs.• Plateau airway

pressure (P plat)• Transairway pressure

– PIP-Pplat• Obstruction• Secretions• RAD

Components of Inflation Pressure


Begin InspirationBegin Inspiration Begin ExpirationBegin Expiration

11

22

BBAA

1. PIP 1. PIP 2. 2. PPplatplat/Alveolar Pressure/Alveolar PressureA. Airway ResistanceA. Airway ResistanceB. Distending PressureB. Distending Pressure


PPawaw(cm H(cm H22O)O)



Begin InspirationBegin Inspiration Begin ExpirationBegin Expiration

11

22

BBAA

1. PIP 1. PIP 2. 2. PPplatplat/Alveolar Pressure/Alveolar PressureA. Airway ResistanceA. Airway ResistanceB. Distending PressureB. Distending Pressure




Ventilator Management• Compliance

– Relationship of volume to pressure

– Dynamic vs static


Lung Compliance Changes in the P-V Loop


Volume (Volume (mLmL))

PIP levelsPIP levels

VVTT


COMPLIANCENormalIncreasedDecreased


Volume Targeted VentilationVolume Targeted Ventilation






VVTT






History of Mechanical Ventilation

• Poliomyelitis– Negative pressure (iron lung)

• WW II– Positive pressure cycled (Bennett and Bird)

• Volume cycle (Emerson)• VT 6-8 ml/kg, Sigh 12-18 ml/kg• VT 10-15ml/kg without sighs• ARDS & PEEP

– Ashbaugh Bigelow and Petty UCHSC 1967

Ventilator Induced Lung InjuryVILI is due to volume (Overdistension)

Ventilation 45 cm H2O

Baseline 5 min 20 min

Dreyfuss Am. Rev. Respir. Dis. 1998; 137: 1159-1164

ARDS is Not Homogeneous

Gattinoni L. Milan Italy

Inflection PointsPaw increases with little change in the volume






VVTT










VVTT







OverdistensionOverdistension

Pressure (cm HPressure (cm H22O)O)

Paw rises with little or no change in VT



OverdistensionOverdistension

Pressure (cm HPressure (cm H22O)O)

Paw rises with little or no change in VT


Lower Upper

ARDSnetARDSnet

NIH NHLBI ARDS Clinical Trials NetworkNIH NHLBI ARDS Clinical Trials Network

ARDS Network: ARMAARDS Network: ARMARespiratory Management in ARDSRespiratory Management in ARDS6 vs. 12 ml/kg Tidal Volume6 vs. 12 ml/kg Tidal Volume

Mode: Volume Assist / Control

Rate: Set rate < 35; adjust for pH goal = 7.30-7.45

OxygenationPaO2 = 55-80 mmHgSaO2 = 88-95%

PEEP 5 5 8 8 10 10 10 .... 20FiO2 .3 .4 .4 .5 .5 .6 .7 .... 1.0

I:E = 1:1.8-1.3

Weaning by Pressure Support when PEEP/FiO2 < 8/.40

New Eng J Med 2000; 342: 1301

ARDS Network: ARMAARDS Network: ARMARespiratory Management in ARDSRespiratory Management in ARDS6 vs. 12 ml/kg Tidal Volume6 vs. 12 ml/kg Tidal Volume12 ml/kg Group

• Initial Vt = 12 ml/kg IBW• If Pplat > 50 cmH20,

reduce Vt by 1 ml/kg.• Minimum Vt = 4 ml/kg• If Pplat < 45 cmH20 and

Vt < 11 ml/kg, increase Vtby 1 ml/kg.

6 ml/kg Group• Initial Vt = 6 ml/kg IBW.• If Pplat > 30 cmH20,

reduce Vt by 1 ml/kg.• Minimum Vt = 4 ml/kg.• If Pplat < 25 cmH20 and

Vt < 5 ml/kg, increase Vtby 1 ml/kg.

New Eng J Med 2000; 342: 1301


20

25

30

35

40

45

0 1 2 3 4Study Day

cm w

ater

6 ml/kg12 ml/kg

* * * *

New Eng J Med 2000; 342: 1301

Plateau PressurePlateau Pressure

33 + 8

25 + 6


120

140

160

180

200

0 1 2 3 4Study Day

P/F

6 ml/kg12 ml/kg

New Eng J Med 2000; 342: 1301

* * *

0

2

4

6

8

10

0 1 2 3 4 7 14 21Study Day

PEEP (cm water)

6 ml/kg12 ml/kg* *

ARDS Network: ARMAARDS Network: ARMARespiratory Management in ARDSRespiratory Management in ARDS6 vs. 12 ml/kg Tidal Volume6 vs. 12 ml/kg Tidal Volume• Vt 6 vs. 12 ml/kg• Mortality• 31.0 vs 39.8%

New Eng J Med 2000; 342: 1301

ARDS Network: ALVEOLIARDS Network: ALVEOLIHigh vs. Low PEEPHigh vs. Low PEEP

• Ventilator management the same as ARMA except PEEP

Lower – PEEP/ Higher FiO2 Treatment GroupFiO2 30 40 40 50 50 60 70 70 70 80 90 90 90 100

PEEP 5 5 8 8 10 10 10 12 14 14 14 16 18 18-24

Higher - PEEP/Lower FiO2 Treatment GroupFiO2 30 30 30 30 30 40 40 50 50 50-80 80 90 100 100PEEP 5 8 10 12 14 14 16 16 18 20 22 22 22 24

N Engl J Med 351:327, July 22, 2004


N Engl J Med 351:327, July 22, 2004

218181206169220168P/F

12.98.412.98.514.78.9PEEP

HighLowHighLowHighLow

Day 7Day 3Day 1Variable


N Engl J Med 351:327, July 22, 2004

Conclusions•VT goal 6 ml/kg•Pplat limit of 30 cm H2O, •Outcomes are similar whether lower or higher PEEP levels are used.

ARDS Network: FACTTARDS Network: FACTTFluids and Catheter Treatment TrialFluids and Catheter Treatment TrialPAC vs. CVP

N Engl J Med 354:2213, May 25, 2006

ARDS Network: FACTTARDS Network: FACTTConservative vs. Liberal Fluid

N Engl J Med 354:2564, June 15, 2006


N Engl J Med 354:2564, June 15, 2006

7

6

5

4

3

2

1

D

130458314332163226363912751

-144508331633343159378215858

-226483344433583201382516473

-165563360631883430375215480

-408936379730603390399716665

-3761642396628243590446715772

11862529304325014230502914874

ConserveLiberalConserveLiberalConserveLiberalConserveLiberal

Balance ml/dOutput ml/dIntake ml/dFurosemide mg/d

7 day fluid balance 7 day fluid balance 69926992++502 502 --136136++491491


N Engl J Med 354:2564, June 15, 2006


N Engl J Med 354:2564, June 15, 2006

.061014Dialysis (60d)

.00113.411.2ICU-FD (28d)

.00114.612.1VFD (28d)

0.3025.5%28.4%Death (60d)

PConserveLiberalOutcome

ARDS Network: LASRSARDS Network: LASRSLate ARDS Steroid Rescue Study

28.6 v 29.2%Methylprednisolone•2 mg/kg load •0.5 mg / kg q 6 for 14d, •0.5 mg / kg q 12 for 7d, •Taper over 4 days•Taper over a 2 days if

septic shock•Intensive infection surveillance

New Eng J Med Volume 2006; 354:1671-1684

ARDS Network: LASRSARDS Network: LASRSLate ARDS Steroid Rescue Study

Placebo (91) MP (89) pMortality (60d) 28.6% 29.2% 1.0VFD (28d) 6.8 + 8.5 11.2 + 9.4 .001ICU FD (28d) 6.2 + 7.8 8.9 + 8.2 .02Myopathy (no.) 0 9 .001Infections / pts 43/30 25/20 .14Amylase (D7) 73 +50 125 + 131 .003Glucose (D7) 144.0 + 61.8 158.7 + 64.4 .14

New Eng J Med Volume 2006; 354:1671-1684

Institute for Healthcare Improvement (IHI)Ventilator Bundle

• HOB > 30o

• DVT prophylaxis• PUD Prophylaxis• Daily sedative vacation and assessment of

readiness to extubate

http://www.ihi.org/IHI/

Mechanical VentilationWeaning• What was the reason for intubation?• Has that reason been resolved?• Can patient protect airway?• Can patient handle secretions?• Oxygenation?• Ventilation? (CO2)• Others: Cardiac function, acid base, abdomen,

renal function• 35% prediction

– “You will never find a fever if you do not measure a temperature?”

Nonphysicain Directed Weaning

Ely AmJRCCM 1999; 159: 439 Kollef CCM 1997; 25: 567

Protocol

Ordered

Daily Sedative Vacation

Kress New Eng J Med 2000

Vacation

Control

Mechanical VentilationWeaning

– Pressure Support• Gradual reduction in

ventilator work is assumed by the patient

– SIMV + PS• Some breaths are

ventilator work and some are patient work

– T-piece• Discontinuation of

ventilator work is assumed by patient.

Brochard AJRCCM 1994; 150: 896

Esteban NEJM 1995; 332: 345

PSV

SBT q d

Mechanical VentilationFailure to Wean

• Increase in demands– Abnormal respiratory mechanics

• RAD• Decrease C

– Unresolved infection• Fever = Me = work

• Decrease in patient capability

– Sedation– Weakness

• Malnutrition• Neuro- or Myo-pathy

– Chest wall mechanics

Total Support Ventilator Independence

Demands Capability

Deleterious work Tolerable load

Weaning Guidelines

• Daily assessment of potential• Spontaneous breathing trials (30-120 min)• Stable support between SBTs• Ability to protect airway• Reverse causes of failure• Weaning protocols for nonphysician• Prolonged ventilation=slow gradual

lengthening of SBTs

Chest 2001; 120: 375S

Mechanical VentilationWeaning• Withdrawl of the ventilator• Test for successful extubation

– Vt 5-7 ml/kg– RR < 30– Me < 15 L– RR/Vt < 105– NIF < 20– FVC 10-15 ml/kg

10% Failure

Questions?KISS

mechanical ventilation for dummies

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