Chest UpdateChest UpdateWeaning from Mechanical VentilationWeaning from Mechanical Ventilation

Statement of the Sixth International Consensus Conference on Intensive CarStatement of the Sixth International Consensus Conference on Intensive Care Medicinee Medicine

Organised jointly by the European Respiratory Society (ERS), the American Organised jointly by the European Respiratory Society (ERS), the American Thoracic Society (ATS), the European Society of Intensive Care Medicine Thoracic Society (ATS), the European Society of Intensive Care Medicine

(ESICM), the Society of Critical Care Medicine (SCCM) and the Soci(ESICM), the Society of Critical Care Medicine (SCCM) and the Sociééttéé de de RRééanimation de Langue Frananimation de Langue Franççaise (SRLF), and approved by the ERS Execuaise (SRLF), and approved by the ERS Execu

tive Committee, February 2007tive Committee, February 2007

15 October, 200715 October, 2007

The Jury Answered the Following The Jury Answered the Following Five Specific QuestionsFive Specific Questions

1)1) What is known about the epidemiology of weaning What is known about the epidemiology of weaning problems? problems?

2)2) What is the pathophysiology of weaning failure?What is the pathophysiology of weaning failure?

3)3) What is the usual process of initial weaning from thWhat is the usual process of initial weaning from the ventilator? e ventilator?

4)4) Is there a role for different ventilator modes in more Is there a role for different ventilator modes in more difficult weaning? difficult weaning?

5)5) How should patients with prolonged weaning failurHow should patients with prolonged weaning failure be managed?e be managed?

Question 1: What is Known About the Question 1: What is Known About the Epidemiology of Weaning Problems?Epidemiology of Weaning Problems?

Schematic Representation of the Different Stages Occurring in aSchematic Representation of the Different Stages Occurring in aMechanically Ventilated PatientMechanically Ventilated Patient

Definition of the different stages, from initiation to mechanical ventilation to weaningDefinition of the different stages, from initiation to mechanical ventilation to weaning

StagesStages DefinitionsDefinitions

Treatment of ARFTreatment of ARF Period of care and resolution of the disorder that caused respiratory failure and prompted Period of care and resolution of the disorder that caused respiratory failure and prompted mechanical ventilationmechanical ventilation

SuspicionSuspicion The point at which the clinician suspects the patient may be ready to begin the weaning The point at which the clinician suspects the patient may be ready to begin the weaning process process

Assessing readiness to weanAssessing readiness to wean Daily testing of physiological measures of readiness for weaning (MIP, fR/VT) to determine pDaily testing of physiological measures of readiness for weaning (MIP, fR/VT) to determine probability of weaning successrobability of weaning success

Spontaneous breathing trialSpontaneous breathing trial Assessment of the patient’s ability to breathe spontaneouslyAssessment of the patient’s ability to breathe spontaneously

ExtubationExtubation Removal of the endotracheal tubeRemoval of the endotracheal tube

ReintubationReintubation Replacement of the endotracheal tube for patients who are unable to sustain spontaneous Replacement of the endotracheal tube for patients who are unable to sustain spontaneous ventilation ventilation

ARF: acute respiratory failure, MIP: maximal inspiratory pressure, fR/VT: respiratory frequency to tidal volume ratio (rapid shallow breARF: acute respiratory failure, MIP: maximal inspiratory pressure, fR/VT: respiratory frequency to tidal volume ratio (rapid shallow breathing index).athing index).

Martin J. TobinMartin J. Tobin

Weaning Process – 1Weaning Process – 1

Weaning tends to be delayed, Weaning tends to be delayed, – exposing the patient to unnecessary discomfort and exposing the patient to unnecessary discomfort and – increased risk of complications, and increased risk of complications, and – increasing the cost of care.increasing the cost of care.

Time spent in the weaning process Time spent in the weaning process – represents represents 40–50%40–50% of the total duration of mechanical of the total duration of mechanical

ventilationventilation

Mortality increasesMortality increases with with increasing duration of increasing duration of mechanical ventilationmechanical ventilation, in part because of , in part because of – complications of prolonged mechanical ventilation, complications of prolonged mechanical ventilation,

especially especially ventilator-associated pneumoniaventilator-associated pneumonia and and airway traumaairway trauma

Weaning Process – 2Weaning Process – 2

The incidence of unplanned extubation ranges The incidence of unplanned extubation ranges 0.3–160.3–16%%– In most cases (83%)In most cases (83%), the unplanned extubation is , the unplanned extubation is initiated initiated

by the patientby the patient, while , while 17%17% are are accidentalaccidental

Almost half of patientsAlmost half of patients with self-extubation during th with self-extubation during the weaning period do e weaning period do not require reintubationnot require reintubationIncrease in the extubation delay between readiness daIncrease in the extubation delay between readiness day and effective extubation significantly y and effective extubation significantly increases morincreases mortalitytality..– mortality was mortality was 12%12% if there was if there was no delay in extubationno delay in extubation and and

27%27% when extubation was when extubation was delayeddelayed..

Definitions of Weaning Success and FailureDefinitions of Weaning Success and Failure

Weaning failure is defined as Weaning failure is defined as – either the either the failure of SBTfailure of SBT or the need for or the need for reintubation within 48 h following extreintubation within 48 h following ext

ubationubationFailure of SBT is defined by: Failure of SBT is defined by: – objective indices of failure, such as objective indices of failure, such as tachypnoeatachypnoea, , tachycardiatachycardia, , hypertensionhypertension, , hyphyp

otensionotension, , hypoxaemiahypoxaemia or or acidosisacidosis, , arrhythmiaarrhythmia; and ; and – subjective indices, such as subjective indices, such as agitationagitation or or distressdistress, , depressed mental statusdepressed mental status, , diaphodiapho

resisresis and and evidence of increasing effortevidence of increasing effortFailure of a SBT is often related to Failure of a SBT is often related to – cardiovascular dysfunctioncardiovascular dysfunction or or inability of the respiratory pumpinability of the respiratory pump to support the l to support the l

oad of breathing.oad of breathing.Extubation failure may be related to Extubation failure may be related to – the same causes, in addition to the same causes, in addition to – upper airway obstructionupper airway obstruction or or excessive secretionsexcessive secretions..

Failure of extubation is associated with Failure of extubation is associated with high mortality ratehigh mortality rate, , – either by selecting for high-risk patients or either by selecting for high-risk patients or – by inducing deleterious effects such as aspiration, atelectasis and pneumoniaby inducing deleterious effects such as aspiration, atelectasis and pneumonia

Incidence of Weaning Success and FailureIncidence of Weaning Success and Failure

First authorFirst author YrYr SubjectsSubjects Failed initialFailed initial

SBTSBT

Passed InitialPassed Initial

SBTSBT

Re-intubatedRe-intubated Total failedTotal failed

weaningweaning

SuccessfulSuccessful

weaningweaning

FARIASFARIAS 20012001 257257 56 (22)56 (22) 201201 28 (14)28 (14) 84 (32.7)84 (32.7) 173173

ESTEBANESTEBAN 19991999 526526 73 (14)73 (14) 453453 61 (13)61 (13) 134 134 (25.5)(25.5) 392392

VALLVERDUVALLVERDU 19981998 217217 69 (32)69 (32) 148148 23 (16)23 (16) 92 92 (42.4)(42.4) 125125

ESTEBANESTEBAN 19971997 484484 87 (18)87 (18) 397397 74 (19)74 (19) 161 (33.3)161 (33.3) 323323

ESTEBANESTEBAN 19951995 546546 130 (24)130 (24) 416416 58 (14)58 (14) 188 (34.4)188 (34.4) 358358

BROCHARDBROCHARD 19941994 456456 109 (24)109 (24) 347347 8 (3)8 (3) 117 (25.6)117 (25.6) 339339

TotalTotal 24862486 524/24 86 (21%)524/24 86 (21%) 1962/2486 1962/2486 (79%)(79%)

252/1962 252/1962 (13%)(13%) 776 776 (31.2%)(31.2%) 1710/2486 (68.8%)1710/2486 (68.8%)

Data are presented as n or n (%), unless otherwise stated. SBT: spontaneous breathing trialData are presented as n or n (%), unless otherwise stated. SBT: spontaneous breathing trial

N Engl J Med 1995; 332: 345–350N Engl J Med 1995; 332: 345–350Am J Respir Crit Care Med 1998; 158: 1855–1862Am J Respir Crit Care Med 1998; 158: 1855–1862Am J Respir Crit Care Med 1994; 150: 896–903Am J Respir Crit Care Med 1994; 150: 896–903Am J Respir Crit Care Med 1999; 159: 512–518Am J Respir Crit Care Med 1999; 159: 512–518Intensive Care Med 2001; 27: 1649–1654Intensive Care Med 2001; 27: 1649–1654Am J Respir Crit Care Med 1997; 156: 459–465Am J Respir Crit Care Med 1997; 156: 459–465

The increased use of NIV raises the question of The increased use of NIV raises the question of how to define weaning success or failure.how to define weaning success or failure.

Weaning success is defined as Weaning success is defined as – extubation and extubation and

– the absence of ventilatory support 48 h following the extubthe absence of ventilatory support 48 h following the extubation. ation.

Weaning failure is defined as one of the following:Weaning failure is defined as one of the following:– 1) failed SBT; 1) failed SBT;

– 2) reintubation and/or resumption of ventilatory support fol2) reintubation and/or resumption of ventilatory support following successful extubation; or lowing successful extubation; or

– 3) death within 48 h following extubation.3) death within 48 h following extubation.

Classification of Patients According to the Classification of Patients According to the Weaning ProcessWeaning Process

Group/categoryGroup/category DefinitionDefinition

Simple weaningSimple weaning Patients who proceed from initiation of weaning to successful extubatiPatients who proceed from initiation of weaning to successful extubation on the first attempt without difficultyon on the first attempt without difficulty

Difficult weaningDifficult weaning Patients who fail initial weaning and require Patients who fail initial weaning and require up to three SBTup to three SBT or or as long as long as 7 days from the first SBTas 7 days from the first SBT to achieve successful weaning to achieve successful weaning

Prolonged weaningProlonged weaning Patients who Patients who fail at least three weaning attemptsfail at least three weaning attempts or or require require 7 days of 7 days of weaning after the first SBTweaning after the first SBT

SBT: spontaneous breathing trial.SBT: spontaneous breathing trial.

Laurent Brochard

Classification of PatientsClassification of Patients

Simple weaning groupSimple weaning group, represents , represents 69%69% of weaning of weaning patients. patients. – Prognosis in this group is Prognosis in this group is goodgood, with an , with an ICU mortality of ICU mortality of

5%5% and an and an in-hospital mortality of in-hospital mortality of 12%12%..

The remaining patients (The remaining patients (31%31%) represent difficult ) represent difficult weaning and prolonged weaning groups. weaning and prolonged weaning groups. – In this population, In this population, ICU mortality is ICU mortality is 25%25%..

– about about half of the patientshalf of the patients who failed initial SBT ( who failed initial SBT (difficult difficult weaning groupweaning group) still required mechanical ventilation at day 7 ) still required mechanical ventilation at day 7

15% of patients15% of patients would be in the would be in the prolonged weaning groupprolonged weaning group

Question 2: What is the PathophysioloQuestion 2: What is the Pathophysiology of Weaning Failure?gy of Weaning Failure?

Common Pathophysiologies and their Incidence, which may Impact on the AbCommon Pathophysiologies and their Incidence, which may Impact on the Ability to Wean a Patient from Mechanical Ventilationility to Wean a Patient from Mechanical Ventilation

PathophysiologyPathophysiology ConsiderConsider

Respiratory loadRespiratory load Increased work of breathing: inappropriate ventilator settingsIncreased work of breathing: inappropriate ventilator settings

Reduced compliance: pneumonia (ventilator-acquired); cardiogenic or noncardiogenic oedema; pulmonary fibrosis; pulReduced compliance: pneumonia (ventilator-acquired); cardiogenic or noncardiogenic oedema; pulmonary fibrosis; pulmonary haemorrhage; diffuse pulmonary infiltratesmonary haemorrhage; diffuse pulmonary infiltrates

Airway bronchoconstrictionAirway bronchoconstriction

Increased resistive loadIncreased resistive load

During SBT: endotracheal tubeDuring SBT: endotracheal tube

Post-extubation: glottic oedema; increased airway secretions; sputum retentionPost-extubation: glottic oedema; increased airway secretions; sputum retention

Cardiac loadCardiac load Cardiac dysfunction prior to critical illnessCardiac dysfunction prior to critical illness

Increased cardiac workload leading to myocardial dysfunction: dynamic hyperinflation; increased metabolic demand; Increased cardiac workload leading to myocardial dysfunction: dynamic hyperinflation; increased metabolic demand; unresolved sepsisunresolved sepsis

NeuromuscularNeuromuscular Depressed central drive: metabolic alkalosis; mechanical ventilation; sedative/hynotic medicationsDepressed central drive: metabolic alkalosis; mechanical ventilation; sedative/hynotic medications

Central ventilatory command: failure of the neuromuscular respiratory systemCentral ventilatory command: failure of the neuromuscular respiratory system

Peripheral dysfunction: primary causes of neuromuscular weakness; CINMAPeripheral dysfunction: primary causes of neuromuscular weakness; CINMA

NeuropsychologicalNeuropsychological DeliriumDelirium

Anxiety, depressionAnxiety, depression

MetabolicMetabolic Metabolic disturbancesMetabolic disturbances

Role of corticosteroidsRole of corticosteroids

HyperglycaemiaHyperglycaemia

NutritionNutrition OverweightOverweight

MalnutritionMalnutrition

Ventilator-induced diaphragm dysfunctionVentilator-induced diaphragm dysfunction

AnaemiaAnaemia

SBT: spontaneous breathing trial; CINMA: critical illness neuromuscular abnormalities.SBT: spontaneous breathing trial; CINMA: critical illness neuromuscular abnormalities.

Common Pathophysiologies and their Incidence, which may ImpCommon Pathophysiologies and their Incidence, which may Impact on the Ability to Wean a Patient from act on the Ability to Wean a Patient from

Mechanical Ventilation (1)Mechanical Ventilation (1)

Respiratory loadRespiratory load– Increased work of breathing: inappropriate ventilator settingsIncreased work of breathing: inappropriate ventilator settings– Reduced compliance: pneumonia (ventilator-acquired); cardiogenic or Reduced compliance: pneumonia (ventilator-acquired); cardiogenic or

noncardiogenic oedema; pulmonary fibrosis; pulmonary haemorrhage; noncardiogenic oedema; pulmonary fibrosis; pulmonary haemorrhage; diffuse pulmonary infiltratesdiffuse pulmonary infiltrates

– Airway bronchoconstrictionAirway bronchoconstriction– Increased resistive loadIncreased resistive load

During SBT: endotracheal tubeDuring SBT: endotracheal tubePost-extubation: glottic oedema; increased airway secretions; sputum retenPost-extubation: glottic oedema; increased airway secretions; sputum retentiontion

Cardiac loadCardiac load– Cardiac dysfunction prior to critical illnessCardiac dysfunction prior to critical illness– Increased cardiac workload leading to myocardial dysfunction: dynamiIncreased cardiac workload leading to myocardial dysfunction: dynami

c hyperinflation; increased metabolic demand; unresolved sepsisc hyperinflation; increased metabolic demand; unresolved sepsis

Common Pathophysiologies and their Incidence, which may ImpCommon Pathophysiologies and their Incidence, which may Impact on the Ability to Wean a Patient from act on the Ability to Wean a Patient from

Mechanical Ventilation (2)Mechanical Ventilation (2)

NeuromuscularNeuromuscular– Depressed central drive: metabolic alkalosis; mechanical ventilation; sedative/hynotic meDepressed central drive: metabolic alkalosis; mechanical ventilation; sedative/hynotic me

dicationsdications– Central ventilatory command: failure of the neuromuscular respiratory systemCentral ventilatory command: failure of the neuromuscular respiratory system– Peripheral dysfunction: primary causes of neuromuscular weakness; CINMAPeripheral dysfunction: primary causes of neuromuscular weakness; CINMA

NeuropsychologicalNeuropsychological– DeliriumDelirium– Anxiety, depressionAnxiety, depression

MetabolicMetabolic– Metabolic disturbancesMetabolic disturbances– Role of corticosteroidsRole of corticosteroids– HyperglycaemiaHyperglycaemia

NutritionNutrition– OverweightOverweight– MalnutritionMalnutrition– Ventilator-induced diaphragm dysfunctionVentilator-induced diaphragm dysfunction

AnaemiaAnaemia

SBT: spontaneous breathing trial; CINMA: critical illness neuromuscular abnormalitiesSBT: spontaneous breathing trial; CINMA: critical illness neuromuscular abnormalities.

A thorough and systematic search for potentially reversible pathoA thorough and systematic search for potentially reversible pathologies should be conducted in all patients who did not fulfil simpllogies should be conducted in all patients who did not fulfil simpl

e weaning e weaning as previously defined.as previously defined.

Using the definitions put forth in this statement, this places Using the definitions put forth in this statement, this places the the patient in group 2patient in group 2, and , and reversible aetiologiesreversible aetiologies for weaning failu for weaning failure may be categorised as follows: re may be categorised as follows: – respiratory loadrespiratory load, , – cardiac loadcardiac load, , – neuromuscular competenceneuromuscular competence (central and peripheral), (central and peripheral), – critical illness neuromuscular abnormalitiescritical illness neuromuscular abnormalities (CINMA), (CINMA), – neuropsychological factorsneuropsychological factors, and , and – metabolicmetabolic and and endocrine disordersendocrine disorders..

These same factors should be sought in These same factors should be sought in group 3 patientsgroup 3 patients, who , who have required mechanical ventilation for 7 days. have required mechanical ventilation for 7 days. – The pathophysiology of weaning failure in group 3 may be The pathophysiology of weaning failure in group 3 may be complexcomplex an an

d d multifactorialmultifactorial..

Critical Illness Neuromuscular AbnormalitiesCritical Illness Neuromuscular Abnormalities

the most common peripheral neuromuscular disordersthe most common peripheral neuromuscular disorders encountered in the ICU settin encountered in the ICU setting and usually g and usually involve both muscle and nerveinvolve both muscle and nerveThe reported prevalence of CINMA in the literature has varied The reported prevalence of CINMA in the literature has varied 50–100%50–100%

– associated with associated with severity of illnessseverity of illness, , multiple organ dysfunctionmultiple organ dysfunction, , exposure to corticosteroidexposure to corticosteroidss, , presence of hyperglycaemiapresence of hyperglycaemia and and prolonged ICU stayprolonged ICU stay..

CINMA presents as a CINMA presents as a motor deficitmotor deficit where muscle weakness is where muscle weakness is bilateralbilateral, , symmetricasymmetricall and most marked in the and most marked in the proximal musclesproximal muscles..Electroneuromyographic studies of the limbs show Electroneuromyographic studies of the limbs show sensorimotor axonopathy with psensorimotor axonopathy with preserved velocitiesreserved velocities and and decreased amplitude of compound action potentialsdecreased amplitude of compound action potentials..Neuromuscular transmissionNeuromuscular transmission is is normalnormal except in the case of prolonged neuromusucl except in the case of prolonged neuromusuclar blocade.ar blocade.Myopathy may be confirmed on muscle biopsy and Myopathy may be confirmed on muscle biopsy and type II fibre drop-outtype II fibre drop-out with a with a losloss of myosin filamentss of myosin filaments is a consistent finding. is a consistent finding.The contribution of CINMA to prolonged mechanical ventilationThe contribution of CINMA to prolonged mechanical ventilation

– an association between CINMA and an an association between CINMA and an increased duration of weaningincreased duration of weaning or or weaning failureweaning failure– CINMA was an CINMA was an independent risk factorindependent risk factor for duration of mechanical ventilation and weani for duration of mechanical ventilation and weani

ng failure, including the need for tracheostomy.ng failure, including the need for tracheostomy.

Neuromuscular dysfunction related to CINMA Neuromuscular dysfunction related to CINMA usually improves over weeksusually improves over weeks but so but some disability may persist over months and interfere with activities of daily living.me disability may persist over months and interfere with activities of daily living.

Psychological dysfunctionPsychological dysfunctionDeliriumDelirium

– Delirium, or acute brain dysfunction, is a disturbance of the level of cognition and arousaDelirium, or acute brain dysfunction, is a disturbance of the level of cognition and arousal and, in ICU patients,l and, in ICU patients,

has been associated with many modifiable risk factors, including: has been associated with many modifiable risk factors, including: use of psychoactive drugsuse of psychoactive drugs; ; ununtreated paintreated pain; ; prolonged immobilisationprolonged immobilisation; ; hypoxaemiahypoxaemia; ; anaemiaanaemia; ; sepsissepsis; and ; and sleep deprivationsleep deprivation..

– The The prevalence of deliriumprevalence of delirium has been reported to range has been reported to range 22–80%22–80%..– It is associated with It is associated with prolonged ICU stayprolonged ICU stay and is and is a predictor of higher mortalitya predictor of higher mortality up to 6 mo up to 6 mo

nths after discharge from the ICU.nths after discharge from the ICU.

Anxiety and depressionAnxiety and depression– The The prevalence of anxietyprevalence of anxiety during ICU is reported to be during ICU is reported to be 30–75%30–75%..– Patients report the following as important contributors to anxiety: Patients report the following as important contributors to anxiety: dyspnoeadyspnoea; ; inability to cinability to c

ommunicateommunicate; and ; and sleep disruptionsleep disruption..– Sleep studiesSleep studies have shown that patients are have shown that patients are unable to rest or sleepunable to rest or sleep, and , and 25% report nightm25% report nightm

aresares..– Polysomnographic studiesPolysomnographic studies show that ICU patients suffer from show that ICU patients suffer from frequent arousalsfrequent arousals and and sleep sleep

fragmentationfragmentation..– Depression may occur as a discrete disorder or in association with ICU delirium.Depression may occur as a discrete disorder or in association with ICU delirium.– Several strategies have been reported to minimise anxiety during mechanical ventilation.Several strategies have been reported to minimise anxiety during mechanical ventilation.

These include: These include: improvement of speech by increasing inspiratory time and PEEPimprovement of speech by increasing inspiratory time and PEEP, or , or ventilating ventilating with bi-level PSVwith bi-level PSV; ; improvement of sleep by minimising noise, light and nursing interventions aimprovement of sleep by minimising noise, light and nursing interventions at nightt night; and ; and the use of relaxation techniquesthe use of relaxation techniques, such as biofeedback., such as biofeedback.

NutritionNutritionOverweightOverweight– The mechanical effects of obesity (overweight is defined as The mechanical effects of obesity (overweight is defined as body mass body mass

index index 25 kg/m 25 kg/m22) with ) with decreased respiratory compliancedecreased respiratory compliance, , high closing high closing volume/functional residual capacity ratiovolume/functional residual capacity ratio and and elevated WOBelevated WOB might be might be expected to impact on expected to impact on the duration of mechanical ventilationthe duration of mechanical ventilation..

– the ARDS Network trials of mechanical ventilation (6 versus 12 mL/kg the ARDS Network trials of mechanical ventilation (6 versus 12 mL/kg VT), the VT), the duration of mechanical ventilationduration of mechanical ventilation was was similarsimilar for overweight for overweight and obese patients compared with the normal body weight group (18.5and obese patients compared with the normal body weight group (18.5–24.9 kg/m–24.9 kg/m22))

– the effect of obesity on the effect of obesity on length of ICU staylength of ICU stay, which was , which was increasedincreased, but th, but the e duration of mechanical ventilationduration of mechanical ventilation was was notnot

MalnutritionMalnutrition– Although malnutrition has been reported in as high as Although malnutrition has been reported in as high as 40%40% of critically of critically

ill patients, data linking it to weaning difficulty are ill patients, data linking it to weaning difficulty are limitedlimited..– Underweight patients, defined as those with a body mass index Underweight patients, defined as those with a body mass index 20 kg 20 kg

/m/m22, may suffer , may suffer depressed ventilatory drivedepressed ventilatory drive, , limited muscle masslimited muscle mass and and wweaning difficultyeaning difficulty..

Question 3: What is the Usual Process Question 3: What is the Usual Process of Initial Weaning from the Ventilator?of Initial Weaning from the Ventilator?

Considerations for Assessing Readiness to WeanConsiderations for Assessing Readiness to WeanClinical assessmentClinical assessment Adequate coughAdequate cough

Absence of excessive tracheobronchial secretionAbsence of excessive tracheobronchial secretion

Resolution of disease acute phase for which the patient was intubatedResolution of disease acute phase for which the patient was intubated

Objective measurementsObjective measurements Clinical stabilityClinical stability

Stable cardiovascular status (i.e. fC Stable cardiovascular status (i.e. fC 140 beats/min, systolic BP 90–160 140 beats/min, systolic BP 90–160 mmHg, no or minimal vasopressors) mmHg, no or minimal vasopressors)

Stable metabolic statusStable metabolic status

Adequate oxygenationAdequate oxygenation

SaOSaO22 90% on 90% on FIO FIO22 0.4 (or PaO 0.4 (or PaO22/FIO/FIO22 150 mmHg) 150 mmHg)

PEEP PEEP 8 cmH 8 cmH22OO

Adequate pulmonary functionAdequate pulmonary function

fR fR 35 breaths/min 35 breaths/min

MIP MIP -20– -25 cmH -20– -25 cmH22OO

VT VT 5 mL/kg 5 mL/kg

VC VC 10 mL/kg 10 mL/kg

fR/VT fR/VT 105 breaths/min/L 105 breaths/min/L

No significant respiratory acidosisNo significant respiratory acidosis

Adequate mentationAdequate mentation

No sedation or adequate mentation on sedation (or stable neurologic patient)No sedation or adequate mentation on sedation (or stable neurologic patient)

fC: cardiac frequency; BP: blood pressure; SaOfC: cardiac frequency; BP: blood pressure; SaO22: arterial oxygen saturation; F: arterial oxygen saturation; FIIOO22: inspiratory oxygen fraction; PaO: inspiratory oxygen fraction; PaO22::

arterial oxygen tension; PEEP: positive end-expiratory pressure; fR: respiratory frequency; MIP: maximal inspirato arterial oxygen tension; PEEP: positive end-expiratory pressure; fR: respiratory frequency; MIP: maximal inspiratory pressure; VT: tidal volume; VC: vital capacity. 1 mmHg ry pressure; VT: tidal volume; VC: vital capacity. 1 mmHg 0.133 kPa. 0.133 kPa.

Failure Criteria of Spontaneous Breathing TrialsFailure Criteria of Spontaneous Breathing Trials

Clinical assessment andClinical assessment and

subjective indicessubjective indices

Agitation and anxietyAgitation and anxiety

Depressed mental statusDepressed mental status

DiaphoresisDiaphoresis

CyanosisCyanosis

Evidence of increasing effortEvidence of increasing effort

Increased accessory muscle activityIncreased accessory muscle activity

Facial signs of distressFacial signs of distress

DyspnoeaDyspnoea

Objective measurementsObjective measurements PaOPaO22 50–60 mmHg on FIO 50–60 mmHg on FIO22 0.5 or SaO 0.5 or SaO22 90% 90%

PaCOPaCO22 50 mmHg or an increase in PaCO 50 mmHg or an increase in PaCO22 8 mmHg 8 mmHg

pH pH 7.32 or a decrease in pH 7.32 or a decrease in pH 0.07 pH units 0.07 pH units

fR/VT fR/VT 105 breaths/min/L 105 breaths/min/L

fR fR 35 breaths/min or increased by 35 breaths/min or increased by 50% 50%

fC fC 140 beats/min or increased by 140 beats/min or increased by 20% 20%

Systolic BP Systolic BP 180 mmHg or increased by 180 mmHg or increased by 20% 20%

Systolic BP Systolic BP 90 mmHg 90 mmHg

Cardiac arrhythmiasCardiac arrhythmias

PaOPaO22: arterial oxygen tension; FIO: arterial oxygen tension; FIO22: inspiratory oxygen fraction; SaO: inspiratory oxygen fraction; SaO22: arterial oxygen saturation; PaCO: arterial oxygen saturation; PaCO22: arteri: arteri

al carbon dioxide tension; fR: respiratory frequency; VT: tidal volume; fC: cardiac frequency; BP: blood pressual carbon dioxide tension; fR: respiratory frequency; VT: tidal volume; fC: cardiac frequency; BP: blood pressure. 1 mmHg re. 1 mmHg 0.133 kPa. 0.133 kPa.

The spontaneous breathing trialThe spontaneous breathing trial

There appears to be There appears to be no differenceno difference in either the percentage of patients who pass the SBT or the in either the percentage of patients who pass the SBT or the percentage of patients successfully extubated when a T-tube trial is compared with the use of lpercentage of patients successfully extubated when a T-tube trial is compared with the use of low levels of pressure support (PS), such as 7 cmHow levels of pressure support (PS), such as 7 cmH22O or 8 cmHO or 8 cmH22O in adults or 10 cmHO in adults or 10 cmH22O in paO in paediatric patients, or the use of CPAP.ediatric patients, or the use of CPAP.patients who fail an SBT do so patients who fail an SBT do so within the first within the first 20 min20 min, so the success rate for an initial SBT , so the success rate for an initial SBT is is similarsimilar for a 30-min compared with a 120-min trial. for a 30-min compared with a 120-min trial.Criteria for passing SBT include Criteria for passing SBT include respiratory patternrespiratory pattern, , adequate gas exchangeadequate gas exchange, , haemodynamic sthaemodynamic stabilityability and and subject comfortsubject comfort..only only 13%13% of patients who successfully passed the SBT and were extubated required reintubati of patients who successfully passed the SBT and were extubated required reintubationonIn patients who do not receive an SBT and are extubated, the failure rate is In patients who do not receive an SBT and are extubated, the failure rate is 40%40%..Patients who successfully pass the SBT Patients who successfully pass the SBT should be extubatedshould be extubated if neurological status, excessive s if neurological status, excessive secretions and airway obstruction are not issues.ecretions and airway obstruction are not issues.Although depressed mentation is frequently considered a contra-indication to extubation,Although depressed mentation is frequently considered a contra-indication to extubation,

– a a low reintubation rate (9%)low reintubation rate (9%) in stable brain-injured patients with a in stable brain-injured patients with a Glasgow coma score Glasgow coma score 44..

Poor cough strengthPoor cough strength and and excessive endotracheal secretionsexcessive endotracheal secretions were more common in patients wh were more common in patients who failed extubation following a successful SBT. o failed extubation following a successful SBT.

– In patients with neuromuscular ventilatory failure, a In patients with neuromuscular ventilatory failure, a peak cough flow of 160 L/minpeak cough flow of 160 L/min correlated with ex correlated with extubation success. tubation success.

When upper airway obstruction due to oedema is a potential concern, a When upper airway obstruction due to oedema is a potential concern, a positive leak testpositive leak test is ad is adequate before proceeding with extubation.equate before proceeding with extubation.

Question 4: Is there a Role for Question 4: Is there a Role for Different Ventilator Modes in More Different Ventilator Modes in More

Difficult Weaning?Difficult Weaning?

Criteria for Extubation FailureCriteria for Extubation Failure

fR fR 25 breaths/min for 2 h 25 breaths/min for 2 hfC fC 140 beats/min or sustained increase or decrease of 140 beats/min or sustained increase or decrease of 20% 20%Clinical signs of respiratory muscle fatigue or increased work Clinical signs of respiratory muscle fatigue or increased work of breathing SaOof breathing SaO22 90%; PaO 90%; PaO22 80 mmHg on FIO 80 mmHg on FIO22 0.50 0.50

Hypercapnia (PaCOHypercapnia (PaCO22 45 mmHg or 45 mmHg or 20% from pre-extubati 20% from pre-extubation), pH on), pH 7.33 7.33

fR: respiratory frequency; fC: cardiac frequency; SaOfR: respiratory frequency; fC: cardiac frequency; SaO22: arterial o: arterial oxygen saturation; PaOxygen saturation; PaO22: arterial oxygen tension; FIO: arterial oxygen tension; FIO22: inspirat: inspiratory oxygen fraction; PaCOory oxygen fraction; PaCO22: arterial carbon dioxide tension. 1 : arterial carbon dioxide tension. 1 mmHg mmHg 0.133 kPa 0.133 kPa

Pressure support ventilationPressure support ventilationPSVPSV is commonly utilised and is the sole mode of me is commonly utilised and is the sole mode of mechanical ventilation used during the weaning process chanical ventilation used during the weaning process in in 21%21% of patients. of patients.Overall, there is consensus from the group and Overall, there is consensus from the group and strong strong supportsupport from the literature for the use of PSV as a we from the literature for the use of PSV as a weaning mode aning mode after initial failed SBTafter initial failed SBT (for (for group 2group 2))The use of PSV may also be helpful in liberating patiThe use of PSV may also be helpful in liberating patients from mechanical ventilation ents from mechanical ventilation after several failed aafter several failed attempts at spontaneous breathingttempts at spontaneous breathing ( (group 3group 3).).The literature does The literature does not supportnot support the use of the use of SIMV aloneSIMV alone as a weaning mode and as a weaning mode and little data existlittle data exist for the use of for the use of SIMV and PSV combinedSIMV and PSV combined..

Noninvasive ventilationNoninvasive ventilation

Alternative weaning technique for patients who failed Alternative weaning technique for patients who failed conventional weaningconventional weaning– 1) might be useful as a bridge to total withdrawal of ventila1) might be useful as a bridge to total withdrawal of ventila

tory support; and tory support; and – 2) would lower ICU morbidity.2) would lower ICU morbidity.

Although NIV is useful in very selected populations, iAlthough NIV is useful in very selected populations, its use ts use cannot be recommended for all patients failing cannot be recommended for all patients failing a SBTa SBTpatients who are extubated to NIV patients who are extubated to NIV should not be consshould not be considered a weaning successidered a weaning success until they are completely lib until they are completely liberated from NIV as a form of therapy for ARFerated from NIV as a form of therapy for ARF

Question 5: How should Patients with Question 5: How should Patients with Prolonged Weaning Failure be Prolonged Weaning Failure be

Managed?Managed?

The Role of TracheostomyThe Role of TracheostomyProposed advantages for tracheostomy include Proposed advantages for tracheostomy include – easier airway management, easier airway management, – improved patient comfort and communication,improved patient comfort and communication,– reduction in sedative use, reduction in sedative use, – earlier weaning from respiratory support, earlier weaning from respiratory support, – improved respiratory mechanics, improved respiratory mechanics, – earlier transition to oral feeding, earlier transition to oral feeding, – reduced oropharyngeal trauma and reduced oropharyngeal trauma and – prevention of ventilator-acquired pneumonia.prevention of ventilator-acquired pneumonia.

Adverse effects include Adverse effects include – misplacement, misplacement, – haemorrhage, haemorrhage, – obstruction, obstruction, – displacement,displacement,– impairment of swallowing reflexes and impairment of swallowing reflexes and – late tracheal stenosis.late tracheal stenosis.

The Role of Tracheostomy – The Role of Tracheostomy – Technical, mechanical and safety aspectsTechnical, mechanical and safety aspects

offer a offer a more secure airwaymore secure airway than a translaryngeal tube than a translaryngeal tube with fewer accidental extubationswith fewer accidental extubations

reduce WOBreduce WOB by improving some aspects of pulmonar by improving some aspects of pulmonary mechanicsy mechanics

no evidenceno evidence that this is linked to reductions in that this is linked to reductions in weaninweaning timeg time or or length of staylength of stay

reduced ventilator-acquired pneumonia rates in patienreduced ventilator-acquired pneumonia rates in patients with a tracheostomy compared with orotracheal tubts with a tracheostomy compared with orotracheal tubes, es, this effect is inconsistentthis effect is inconsistent

The Role of Tracheostomy –The Role of Tracheostomy –Timing of tracheostomyTiming of tracheostomy

prolonged translaryngeal intubation causes prolonged translaryngeal intubation causes – tissue trauma, tissue trauma, – promotes bacterial translocation and infection, and promotes bacterial translocation and infection, and – usually requires sedation to reduce patient discomfusually requires sedation to reduce patient discomf

ort, ort,

there is there is little evidence to guide optimal timing little evidence to guide optimal timing for a tracheostomyfor a tracheostomy

Mortality and Weaning Process in Patients with Mortality and Weaning Process in Patients with Prolonged Weaning FailureProlonged Weaning Failure

Patients subjected to SBT

FailSBT

Group 1:“simple wean”

Extubated respiratory failure 48 h21% (6.337%)

Weaned Group 2: “difficult weaning” Died447%

Three weaning trial failures, or 7 days since SBT

Group 3: “prolonged weaning”

3392%survive

3189%weaned

Long-termventilation

2375% alive at 1 yr 2252% alive at 5 yrs

Chest 1989; 96: 1120–1124Chest 1989; 96: 1120–1124Anaesthesia 2003; 58: 161–Anaesthesia 2003; 58: 161–165165Mayo Clin Proc 1997; 72: 1Mayo Clin Proc 1997; 72: 13–193–19Am J Respir Crit Care Med Am J Respir Crit Care Med 1999; 159: 1568–15731999; 159: 1568–1573Chest 1995; 108: 226–232Chest 1995; 108: 226–232Intensive Care Med 2002; 2Intensive Care Med 2002; 28: 908–9168: 908–916

The Main RecommendationsThe Main Recommendations

1)1) Patients should be categorised into three groups based on the Patients should be categorised into three groups based on the difficulty and duration of the weaning process. difficulty and duration of the weaning process.

2)2) Weaning should be considered Weaning should be considered as early as possibleas early as possible. . 3)3) A A spontaneous breathing trialspontaneous breathing trial is the major diagnostic test to is the major diagnostic test to

determine whether patients can be successfully extubated. determine whether patients can be successfully extubated. 4)4) The initial trial The initial trial should last 30 minshould last 30 min and consist of either T-tu and consist of either T-tu

be breathing or low levels of pressure support.be breathing or low levels of pressure support.5)5) Pressure supportPressure support or or assist–control ventilation modesassist–control ventilation modes should should

be favoured in patients failing an initial trial/trials. be favoured in patients failing an initial trial/trials. 6)6) Noninvasive ventilation techniquesNoninvasive ventilation techniques should be considered in should be considered in

selected patients to shorten the duration of intubation but selected patients to shorten the duration of intubation but shshould not be routinely used as a tool for extubation failureould not be routinely used as a tool for extubation failure..

Neil MacIntyre Neil MacIntyre Chest Chest 2007;132;1049-10562007;132;1049-1056

Protocolized flow chart for ventilator discontinuationProtocolized flow chart for ventilator discontinuation

Neil MacIntyrNeil MacIntyre e Chest Chest 2007; 2007; 132;1049-1056132;1049-1056