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An Evidence-Based Approach

Ventilator Liberation

Dean Hess

Disclosures

• Philips Respironics

• Ventec Life Support

• Daedalus Enterprises

• Jones and Bartlett

• McGraw-Hill

• UpToDate

• American Board of Internal Medicine

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Balance Between Conservative and Aggressive

Weaning

Prolonged ventilation

• Infection

• Lung/laryngeal injury

• Deconditioning

• Cost

Premature extubation/reintubation

• Prolonged ICU stay

• Upper airway injury

• Infection

• Mortality

A reasonable re-intubation rate is 10-20%

Comparison of Weaning Methods

• Brochard (Am J Respir Crit Care Med 1994; 150:896)

– Patients screened for weaning readiness

– T-piece trial for 2 hrs; ≈75% tolerated and extubated

– Greatest weaning success for PSV (worst for SIMV)

• Esteban (N Engl J Med 1995; 332:345)

– Patients screened for weaning readiness

– T-piece trial for 2 hrs; ≈75% tolerated and extubated

– Greatest weaning success for T-piece (worst for SIMV)

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Commonsense Criteria for SBT

• Evidence for some reversal of the underlying cause for

respiratory failure

• Adequate gas exchange

• Hemodynamic stability

• Capability to initiate an inspiratory effort (pass SAT)

“Weaning” Parameters

• Mechanics

– Spontaneous tidal volume and respiratory rate

– Rapid shallow breathing index

– Vital capacity

– Maximal inspiratory pressure

– Work-of-breathing

• Gas exchange

– PaO2/FIO2, PaO2/PAO2, P(A-a)O2

– Minute ventilation

– Dead spaceWeaning parameters are not predictive!Meade et al, Chest 2001;120:400S

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To RSBI or Not?

• Control: f/VT measured but not used

• Experimental: f/VT was measured and used (threshold of 105

breaths/min/L)

• Weaning time significantly shorter in the group where f/VT was

not used (2 vs 3 days)

• No difference in extubation failure, hospital mortality rate,

tracheostomy, or unplanned extubation.

Tanios, Crit Care Med 2006; 34:2530

• Sedation per usual care + daily SBT compared to daily SAT

followed by SBT

• PaEents in the SAT → SBT group (wake up and breathe) had

more ventilator free days, were discharged from the ICU and

the hospital earlier, and had a lower mortality.

Girard, Lancet 2008;371:126

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ABCDEF Bundle

A. Assess, prevent, and manage pain

B. Both spontaneous awakening trials and spontaneous

breathing trials

C. Choice of analgesia and sedation

D. Delirium: assess, prevent, manage

E. Early mobility and exercise

F. Family engagement and empowerment

Spontaneous Breathing Trials

• Slight benefit for PS or TC over T-piece? (Burns, Crit Care 2017;21:127)

• SBT can be applied on ventilator (0/0 or 5/0)

• 30 min is adequate for spontaneous breathing trial (Esteban et al,

Am J Respir Crit Care Med 1999; 159:512)

• CPAP with 5 cm H2O can produce false positive trials with

COPD and CHF

The Best Weaning Parameter is a Spontaneous Breathing Trial

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Ventilator Approaches to Weaning:

Low Level Evidence• Modes

– Smartcare

– Adaptive support ventilation

– Adaptive pressure control (volume support)

• Aids to SBT

– Pressure support

– Tube compensation

– Proportional assist ventilation

Tobin, AJRCCM 2012

Full or partial ventilatory support

Assess Readiness

Spontaneous breathing trial

Evaluate for extubation

success

fail

comfort

determinecause offailure

Disease resolutionAdequate gas exchangeHemodynamic stabilityAbility to breathe

Upper airway patent (leak test)?Aspiration risk?Able to clear secretions?

Extubate or try again or trach

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Hess and MacIntyre, Am J Respir Crit Care Med 2011;184:392

BMJ 2011;342:c7237

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Failed Spontaneous Breathing Trial

• Auto-PEEP and hyperinflation

• Cardiac disease

• Muscle weakness

• Iatrogenic causes

<Pre-existing (ALS, MG, MD, SCI, GBS)Acquired (CI weakness, diaphragm paralysis)

} Altered respiratory mechanics

The Heart and Weaning Failure

• Myocardial ischemia

Hurford, Anesthesiology 1991; 74:1007

Hurford, Crit Care Med 1995; 23:1475

Chatila, Chest 1996; 109:1577

• Increased preload/afterload with change in intra-thoracic

pressure from positive to negative

Lemaire, Anesthesiology 1988; 69:171

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Lemaire, Anesthesiology 1988;69:171

Acquired Respiratory Muscle Weakness in the ICU

• VIDD: respiratory muscle weakness in a ventilated patient with

no other explanation for the weakness.

– Diaphragm atrophy unusual unless diaphragm activity is completely

suppressed (paralysis)

– Assess with ultrasound?

• Critical illness myopathy and polyneuropathy

– Occurs in 25% - 50% of ventilated patients

• Some respiratory muscle activity good: occasional patient

triggers, mild forms of asynchrony

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Am J Respir Crit Care Med 2014;190:282

Post-Extubation NIV

• Earlier extubation: use with caution

• Prevent extubation failure: recommended in patients at risk

• Rescue failed extubation: use with caution

• Do not use routinely

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Chest 2001;120:375S

ACCP/AARC/SCCM Guidelines

Chest 2001;120:375S

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Chest 2001;120:375S

ACCP/AARC/SCCM Guidelines

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Eur Respir J 2007; 29:1033

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Am J Respir Crit Care Med 2017;195:1477

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Summary

• Weaning parameters are not predictive.

• The best predictor of extubation readiness is a spontaneous

breathing trial.

• The role of ventilator modes to facilitate weaning has not been

established.

• Post-extubation HFNC and NIV useful in selected patients.

• Protocol approaches to weaning have been successful.