Weaning form Mechanical

ventilation: Recent Updates

Gamal Rabie Agmy, MD, FCCP Professor of Chest Diseases , Assiut University

Definition of Weaning

The transition process from

total ventilatory support

to spontaneous breathing.

This period may take many forms

ranging from abrupt withdrawal to

gradual withdrawal from ventilatory

support.

Gamal Agmy

• 75% of mechanically ventilated patients are easy to be weaned off the ventilator with simple process

• 10-15% of patients require a use of a weaning protocol over a 24-72 hours

• 5-10% require a gradual weaning over longer time

• 1% of patients become chronically dependent on MV

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• Simple weaning (group 1) includes

patients who succeed the first weaning trial

and are extubated without difficulty

• Difficult weaning (group 2) includes

patients who fail the first weaning trial and

require up to 3 spontaneous breathing

trials or 7 days to achieve successful

weaning, and

• Prolonged weaning (group 3) includes patients who require more than 7

days of weaning after the first weaning

trial. Gamal Agmy

Readiness To Wean

• Improvement of respiratory failure

• Absence of major organ system failure

• Appropriate level of oxygenation

• Adequate ventilatory status

• Intact airway protective mechanism

(needed for extubation)

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Oxygenation Status

• PaO2 ≥ 60 mm Hg

• FiO2 ≤ 0.40

• PEEP ≤ 5 cm H2O

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Ventilation Status

• Intact ventilatory drive: ability to control

their own level of ventilation

• Respiratory rate < 30

• Minute ventilation of < 12 L to maintain

PaCO2 in normal range

• VD/VT < 60%

• Functional respiratory muscles

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Intact Airway Protective Mechanism

• Appropriate level of consciousness

• Cooperation

• Intact cough reflex

• Intact gag reflex

• Functional respiratory muscles with ability

to support a strong and effective cough

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Function of Other Organ Systems • Optimized cardiovascular function

– Arrhythmias

– Fluid overload

– Myocardial contractility

• Body temperature

– 1◦ degree increases CO2 production and O2 consumption by 5%

• Normal electrolytes

– Potassium, magnesium, phosphate and calcium

• Adequate nutritional status

– Under- or over-feeding

• Optimized renal, Acid-base, liver and GI functions

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• Several indexes have been employed to assess the

patient's ability to recover spontaneous breathing.

• Variables such as minute ventilation (Ve), maximum

inspiratory pressure (PImax), breathing frequency,

rapid shallow breathing index (RSBI, i.e., respiratory

frequency/tidal volume), tracheal airway occlusion

pressure 0.1 s (P 0.1), P0.1/ PImax >0.3,

P0.1Xf/VT<300 , a combined index named CROP

(compliance, rate, O2, pressure index) >13, IWI>25

and CORE >8 have been used in common clinical

practice

Predictors of Weaning Outcome

Gamal Agmy

• P0.1/PImax > 0.3

— P0.1 is pressure at the airway opening

0.1 s after start of inspiratory flow

— Correlates with central respiratory drive

• P0.1 x f/VT <300

• CROP index (dynamic compliance,

respiratory rate, oxygenation, maximum

inspiratory pressure index) >13

— Cdyn x PImax x (PaO2/PAO2)/f

— >13 good

— Cdyn = dynamic compliance

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• IWI (integrative weaning index) >25

— (CRS x SaO2)/(f/VT)

— CRS = static compliance of the

respiratory system

• CORE index (dynamic compliance,

oxygenation, rate, effort) >8

— Cdyn x (PImax/P0.1) x (PaO2/PAO2)/f

Gamal Agmy

• Among the numerous parameters used

in clinical practice, the rapid shallow

breathing index is one of the most

accurate.

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Spontaneous Breathing Trials

SBT to assess extubation readiness

– T-piece ,PS 5-8 cm H2O or CPAP 5 cm H2O

– 30-120 minutes trials

– If tolerated, patient can be extubated

SBT as a weaning method

– Increasing length of SBT trials

– Periods of rest between trials and at night

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Daily SBT

<100

Mechanical Ventilation

RR > 35/min

Spo2 < 90%

HR > 140/min

Sustained 20% increase in HR

SBP > 180 mm Hg, DBP > 90 mm Hg

Anxiety

Diaphoresis

30-120 min

PaO2/FiO2 ≥ 200 mm Hg

PEEP ≤ 5 cm H2O

Intact airway reflexes

No need for continuous infusions of vasopressors or inotrops

RSBI

Extubation No

> 100

Rest 24 hrs

Yes

Stable Support Strategy

Assisted/PSV

24 hours

Low level CPAP (5 cm H2O),

Low levels of pressure support (5 to 7 cm H2O)

“T-piece” breathing

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Failure to Wean

Weaning to exhaustion

Auto-PEEP

Excessive work of breathing

Poor nutritional status

Overfeeding

Left heart failure

Decreased magnesium and phosphate leves

Infection/fever

Major organ failure

Technical limitation

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Weaning to Exhaustion

RR > 35/min

Spo2 < 90%

HR > 140/min

Sustained 20% increase in HR

SBP > 180 mm Hg, DBP > 90 mm Hg

Anxiety

Diaphoresis

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Gamal Agmy

First Recommendation

For acutely hospitalized patients

ventilated more than 24 h, we suggest

that the initial SBT be conducted with

inspiratory pressure augmentation (5-

8 cm H2O) rather than without (T-piece

or CPAP)

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Second Recommendation

For acutely hospitalized patients

ventilated for more than 24 h, we

suggest protocols attempting to

minimize sedation

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Third Recommendation

For patients at high risk for extubation

failure who have been receiving

mechanical ventilation for more than

24 h and who have passed an SBT, we

recommend extubation to preventive

NIV

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Third Recommendation

Patients at high risk for failure of

extubation may include those

patients with hypercapnia, COPD,

congestive heart failure, or other

serious comorbidities

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Noninvasive ventilation as a weaning strategy for

mechanical ventilation in adults with respiratory

failure: a Cochrane systematic review Karen E.A. Burns et al CMAJ 2014. DOI:10.1503

Noninvasive weaning reduces rates of

death and pneumonia without increasing

the risk of weaning failure or reintubation.

In subgroup analyses, mortality benefits

were significantly greater in patients with

COPD Gamal Agmy

Noninvasive ventilation as a weaning strategy for

mechanical ventilation in adults with respiratory

failure: a Cochrane systematic review Karen E.A. Burns et al CMAJ 2014. DOI:10.1503

26. Rabie Agmy GM, Metwally MM. Noninvasive ventilation

in the weaning of patients with acute-on-chronic respiratory

failure due to COPD. Egyptian J Chest Dis

Tuberculosis2012;61:84–91

30. Rabie Agmy GM, Mohamed AZ, Mohamed

RN. Noninvasive ventilation in the weaning of patients with

acute-on-chronic respiratory failure due to

COPD. Chest 2004;126(Suppl 4):755. Gamal Agmy

Official ERS/ATS clinical practice

guidelines: noninvasive ventilation

for acute respiratory failure

134-Gamal MR, Ashraf ZM, Rania NM

. Noninvasive ventilation in the weaning of

patients with acute-on-chronic respiratory failure

due to COPD. Chest 2004; 126: Suppl. 4,755S

136-Agmy GM, Metwally MM. Noninvasive

ventilation in the weaning of patients with acute-

on-chronic respiratory failure due to

COPD. Egyptian Chest Dis &TB 2012; 61: 84–91

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Fourth Recommendation

For acutely hospitalized adults who have

been mechanically ventilated for > 24 h,

we suggest protocolized rehabilitation

directed toward early mobilization

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Fifth Recommendation

We suggest managing acutely

hospitalized adults who have been

mechanically ventilated for > 24 h with a

ventilator liberation protocol

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Sixth Recommendation

We suggest performing a CLT in

mechanically ventilated adults who meet

extubation criteria and are deemed high

risk for PES

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Seventh Recommendation

For adults who have failed a CLT but are

otherwise ready for extubation, we

suggest administering systemic steroids

at least 4 h before extubation; a repeated

CLT is not required

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Diaphragm Ultrasound as a

Novel Guide of Weaning from

Invasive Ventilation

Gamal Agmy , MD , FCCP Professor of Chest Diseases and respiratory ICU,

Assiut University, Assiut , Egypt

Diaphragm Ultrasound as a

Novel Guide of Weaning from

Invasive Ventilation

Gamal Agmy , MD , FCCP Professor of Chest Diseases and respiratory ICU,

Assiut University, Assiut , Egypt

Gamal Agmy

• DT was calculated as percentage

from the following formula:

T end-inspiration − T end-expiration

T end-expiration

• It was recorded at total lung

capacity (TLC) and residual volume

(RV).

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• DT was significantly different between

patients who failed and patients who

succeeded SBT.

• A cutoff value of a DT >40% was

associated with a successful SBT with a

sensitivity of 88%, a specificity of 92%, a

positive predictive value (PPV) of 95%,

and a negative predictive value (NPV) of

82%. Gamal Agmy