weaning from mechanical ventilation

WEANING FROM MECHANICAL VENTILATION IN NEUROLOGICAL PATIENTS-AN EVIDENCE BASED

APPROACH

SUCHARITA RAY

PRECEPTOR: DR KARAN MADANDR DEEPA DASH

01/01/2015

THE CHECKLIST DEFINITION OF WEANING THE BRAIN LUNG INTERACTION WEANING ALGORITHM CLASSIFICATION AND PATHOPHYSIOLOGY THE EXECUTION CRITICAL ILLNESS NEUROMUSCULAR

ABNORMALITIES NEWER MODALITIES OF WEANING

DEFINITION OF WEANING

Hall JB et al, JAMA; 1987Slutsky AS, Chest 1993

“Gradual withdrawalof mechanical ventilation and concomitant

resumption ofspontaneous breathing”

• Ventilatory assistance NEED NOT BE DECREASED GRADUALLY in all patients with acute respiratory failure

• “LIBERATION FROM" and “DISCONTINUATION OF“ mechanical ventilation are now preferred

SOME PRELIMINARIES• 30% of patients admitted to ICUs require

mechanical ventilation

• Delayed weaning increases costs, risks of nosocomial pneumonia, cardiac-associated morbidity, and death.

• Early weaning often results in reintubation, and associated complications due to prolonged ventilation

Esteban A, Anzueto A, Frutos F, et al. Characteristics and outcomes in adult patients receiving mechanical ventilation: a 28-day international study. JAMA 2002; 287:345–355.

JAMA 2002, Vol 287, No 3 ( Reprint)

Context of the Research:

To study the outcome of mechanical ventilation in a large number of unselected, heterogeneous patients.

Objectives

1. To determine the survival of patients receiving mechanical ventilation

2. Relative importance of factors influencing survival.

Esteban A et al. Characteristics and Outcomes in Adult Patients Receiving Mechanical Ventilation: A 28-Day International study. JAMA.2002;287(3):345-355.

Design, Setting, and Subjects:

• Prospective cohort of consecutive adult patients• Admitted to 361 ICUs• Received mechanical ventilation for more than

12 hours • March 1, 1998 - March 31, 1998.

Main Outcome Measure:

All-cause mortality during ICU unit stay.

Esteban A et al. Characteristics and Outcomes in Adult Patients Receiving Mechanical Ventilation: A 28-Day International study. JAMA.2002;287(3):345-355.

SOME OF THE NUMBERS INVOLVED:

• Total number of patients admitted in the study period: 15757

MEDICAL/SURGICAL: 77% MEDICAL 19% SURGICAL 4%

• Total number of patients receiving mechanical ventilation for more than 12 hours: 5183 (33%)

• Total number of patients followed up for entire course of mechanical ventilation: 5131 ( 99%)

THE ATTEMPT AT WEANING:

TOTAL NUMBER: 5199 attempts in 3640 (70.2%) patients

• Once-daily weaning trial--- 2833 (77.8%) attempts• Multiple weaning trials--- 510 (14.0%) attempts• Gradual reduction of pressure support--- 752

(20.7%) attempts

WEANING METHODS:

• T-tube------------------1725 (51.6%) attempts• CPAP------------------ 643 (19.2%) attempts• PS of 7 cm H2O---- 943 (28.2%) attempts

FACTORS INDEPENDENTLY ASSOCIATED WITH MORTALITY

AgeSAP II Score at ICU AdmissionPrior functional statusMV initiated due to coma of any causeARDSSepsisInotropic supportMODS

JAMA, January 16,2002; Vol 287, No 3

Lone and Walsh Critical Care 2011, 15:R102

METHODS: Retrospective Cohort Study

STUDY LOCATION: 3 ICU units in a UK region from 2002 to 2006.

PROLONGED MECHANICAL VENTILATION: Requiring mechanical ventilation 21 days or more

OUTCOMES: Mortality and Hospital Resource Use

Lone and Walsh Critical Care 2011, 15:R102

Age mean (SD) 349 7,499 59.6 (15.2)

56.9 (18.1)

0.001

CPR in 24 hours before ICU admission n (%)

349 7,499 23 (6.6) 663 (8.8) 0.15

Number of co-morbidities n (%)

340 7,228 <0.001

None 276 (81.2)

5,317(73.6)

1 50 (14.7) 1,211 (16.8)

2 or more 14 (4.1) 700 (9.7)Surgical status n (%) 347 7,463 <0.00

1

Tracheostomy placed during admission n (%)

349 7,499 219 (62.8)

470 (6.3) <0.001

ICU mortality n (%) 317 7,103 83 (26.2) 1,654 (23.3)

0.23

Hospital mortality n (%)

305 6,763 123(40.3)

2,286(33.8)

0.02

Length of ICU stay (days)

Mean no of days

349 7,499

37.2(16.1)

3.8 (4.9)

No of days ventilated

Mean (SD)

349 7,499

33.2 14.7)

2.9 (4.2)

THE BRAIN LUNG INTERACTION ARDS survivors show persistent cognitive deterioration at discharge

Mechanisms of cognitive dysfunction?Hypoxemia

Hypoxia- HIF-1alpha and HIF-2alpha

HYPOXIA INDUCED FACTORS HAVE A ROLE IN:

Angiogenesis, Energy metabolismCell survival/ Neural stem cell growthMiltbrand EB, Angus DC: Potential mechanisms and markers of critical illness-associated cognitive dysfunction. Curr Opin Crit Care 2005, 11:355-359.

There is no such thing as an isolated head injury

Target of MODS.

Progression to ALI

DeliriumDementia Cognitive decline Loss of IQMood disordersMemory disorders

MAN MACHINE MAN

Gonzalvo R, Marti-Sistac O, Blanch L, Lopez- Aguilar J. Bench-to-bedside review: brain-lung interaction in the critically ill–a pending issue revisited. Crit Care. 2007;11(3):216.

(1) improve brain oxygenation

THERAPEUTIC TARGETS OF VENTILATION IN THE NEUROLOGICALLY ILL PATIENT

(2) improve cerebral blood flow.(3) discordant therapeutic targets

Lowe GJ, Ferguson ND. Lung-protective ventilation in neurosurgical patients. Curr Opin Crit Care. 2006;12(1):3

YES / NO? IF YES THEN HOW

THE NEURO ICU GUY ON A VENTILATOR

Cochrane Database of Systematic Reviews 2014, Issue 11. Art. No.: CD006904. DOI: 10.1002/14651858.CD006904.pub3.

OBJECTIVES

1. Comparison of total duration of mechanical ventilation of using protocols versus non-protocolized practice.

2. Differences in outcomes measuring weaning duration, harm (adverse events) and resource use (intensive care unit (ICU) and hospital length of stay, cost)

3. Variations in outcomes by type of ICU, type of protocol and approach to delivering the protocol (professional-led or computer-driven).


SELECTION CRITERIA:

Randomized controlled trials (RCTs) and quasi-RCTs of protocolized weaning versus non-protocolized weaning in critically ill adults.

Main results:17 trials (with 2434 patients)


AUTHORS’ CONCLUSIONSUse of protocols can be said to have:

1. Reduced duration of mechanical ventilation2. Reduced weaning duration3. Reduced length of ICU stay

Protocolized approach brought about these reductions in medical, surgical and mixed ICUs

Protocolized approach did not bring about any effect in neurosurgical ICUs.


JM Boles et al Eur Respir J 2007: 29: 1033-1056A Esteban et al Chest 1994: 106: 1188-1193Tindol GA et al Chest 1994: 105: 1804-1807

Admit

Discharge

Treatment of ARF

Assess readiness to wean

Extubation ? Reintubation

Suspicion SBTSuspicion

Assess readines

s to wean

40- 50% of total duration of mechanical ventilation

Unplanned extubation – 0.3- 16%

~50% do not require re intubation

THE WEANING ALGORITHM

TERMINOLOGY

Extubation & absence of ventilatory support 48hrs post

extubation

Failed SBTReintubation/resumption of ventilatory support post extubationDeath within 48hrs post extubation

SUCCESS

FAILURE

JM Boles et al Eur Respir J 2007: 29: 1033-1056

CLASSIFICATION

SIMPLE

• 70 %• Single SBT

DIFFICULT

• 15 – 20 %• Upto 3 SBT• Upto 7 days

after first SBT

PROLONGED

• 10 - 15%• > 3 SBT• > 7 days after

first SBT


PATHOPHYSIOLOGY

• Neuromuscular - CINMA

• Neuropsychological

• VIDD• Metabolic• Overweight

• Baseline Status

• Demand

• Airway Resistance• Compliance• Settings

Respiratory Cardiac

Neurological

Nutritional and

Metabolic

VIDD : Ventilator Induced Diaph. Dysfunction CINMA : Critical Illness NeuroMusc Abnromalities

RESPIRATORY LOAD

Increased WOB

Inappropriate ventilator settingsPatient ventilator

dyssynchrony

Compliance

PneumoniaPulmonary edema

Fibrosis Chest wall

Resistance

BronchospasmDHI

ET tubeGlottic edema



Admit

? Discharg

e

Treatment of ARF


SuspicionSuspicion

Assess readines

s to wean

Identifying Candidates for a Trial of Spontaneous Breathing

MacIntyre NR. Evidence-based assessments in the ventilator discontinuation process. Respir Care 2012; 57:1611–1618.

Respiratory Criteria:PaO2 ≥ 60 mm Hg on FiO2 ≤ 0.4;PEEP ≤ 5–10 cm H2O; PaO2/FiO2 ≥ 150–300)PaCO2 at normal or baseline levelsAble to initiate a respiratory effort ( PI max > - 30 cm H20)

Cardiovascular CriteriaStable CV System ( HR ≤ 140; stable BP; no (or minimal) pressors)

Identifying Candidates for a Trial of Spontaneous Breathing

MacIntyre NR. Evidence-based assessments in the ventilator discont process. Respir Care 2012; 57:1611–1618.

Appropriate Mental StatusAdequate mentation(Arousable, GCS ≥ 13, no continuous sedative infusions)

Absence of Correctible Comorbid Conditions

Afebrile (temperature 38°C)Adequate hemoglobin (Hb 8–10 g/dL)Stable metabolic status (Acceptable electrolytes)

Physician believes in possibility of discontinuation

READINESS ASSESSMENT“The Wean Screen”Subjective

Adequate cough

Absence of excessive

tracheobronchial secretion

Resolution of disease acute phase

Objective

Hemodynamic stability

Stable metabolic status

Adequate oxygenation

Adequate mentation

Adequate pulmonary function


Measurements Used to Predict a Successful Trial of Spontaneous Breathing

Measurement Threshold for Success

Range of likelihood

RatiosTidal Volume (Vt) 4-6 ml/kg 0.7-3.8

Respiratory Rate (RR)

30-38 bpm 1.0-3.8

RR/Vt Ratio 60-105 bpm/L 0.8-4.7

Maximum Inspiratory

Pressure ( P I max)

-15 to -30 cm of H2O

1.0-3.0

MacIntyre NR. Evidence-based assessments in the ventilator discontinuation process. Respir Care 2012; 57:1611–1618.


Admit

? Discharge

Treatment of ARF


Suspicion SBT

THE SPONTANEOUS BREATHING TRIAL

THE TRADITIONAL APPROACH:

Gradual reduction in ventilatory support over hours to days

Put patients back on a ventilator at night to “rest them”

Spontaneous breathing trials (SBTs) are conducted with no ventilatory support

(To help identify patients capable of unassisted breathing)

Using the Ventilator

CircuitPressure Support

Disconnecting the Ventilator

METHODS OF SPONTANEOUS BREATHING TRIALS

FORMS OF SPONTANEOUS BREATHING TRIALS

Low level of CPAP (5 cm

H2O)

Low levels of PSV (5-8 cm

H2O)

Flow-triggering

with no pressure support

T- piece breathing

Esteban A et al Am J Respir Crit Care Med 1997

I-Using the Ventilator Circuit Often conducted while the patient breathes

through the ventilator circuit. Advantage: Can monitor the tidal volume (VT)

and respiratory rate (RR), Rapid, shallow breathing (indicated by an

increase in the RR/VT ratio) is a common breathing pattern in patients who fail the SBT.

Drawback: Resistance to breathing through the ventilator circuit Increased work of breathing

II-Pressure Support Low levels of pressure support (5 cm H2O) are

used.

To counteract the resistance to breathing through the ventilator circuit,

What is the benefit?

No PSV PSV 1 Hr Post Extubn

5040

90

Work of Breathing during SBT with/out PSV

Number of Patients

Wor

k of

bre

athi

ng J/

L

Mehta S, Nelson DL, Klinger JR, et al. Prediction of post-extubation work ofbreathing. Crit Care Med 2000; 28:1341–1346.

Simple breathing circuit for spontaneous breathing trials that are independent of the ventilator.

The T-shaped adapter in the circuit is responsible for thepopular term T-piece that is used for this circuit

The T-piece

The theoretical advantages of the T-piece

The work of breathing is lower when breathing through a T-piece circuit compared to a ventilator circuit (although this is unproven).

The major disadvantage of the T-piece circuit is the inability to monitor the respiratory rate and

tidal volume.

RSBI – Rapid Shallow Breathing Index

• 1 min after spontaneous breathing• < 105 breaths/min/l

Yang KL, TobinMJ, N Engl J Med 1991

RSBI = Respiratory rate (per min) Tidal volume (L)

SEARCH PERIOD: 1971 to 1998

DATABASES SEARCHED: MEDLINE, EMBASE, HealthSTAR, CINAHL, the Cochrane Controlled Trials Register and the Cochrane Database of Systematic Reviews.

Weaning interventions: ‘For stepwise reductions in mechanical support, PSV/multiple daily T-piece trials could be superior to SIMV.’

‘For trials of unassisted breathing, low levels of pressure support could be beneficial.’

These thresholds are not completely based on objective data and appear to be related

to physician judgement.


Admit

Discharge

Treatment of ARF


Extubation ? Reintubation

Suspicion SBT

(CHEST 2006; 130:1664–1671)

“ To assess the factors associated with reintubation in patients who had successfully passed a SBT.”

Methods:Prospectively collected clinical data from adults admitted to ICUs of 37 hospitals in eight countries

Readiness-to-wean criteria: (1)Improvement in the underlying condition that led to

ARF(2)Alert/able to communicate(3)Core temperature not > 38°C(4)No therapy with vasoactive drugs (5) Adequate gas exchange, as indicated by a Po2 of at least 60

Undergone invasive mechanical ventilation for > 48 h Deemed ready for extubation.

Success vs. Failure1. Signs of respiratory distress: Agitation,

diaphoresis, rapid breathing, and use of accessory muscles of respiration.

2. Signs of respiratory muscle weakness: Paradoxical inward movement of the abdominal wall during inspiration.

3. Adequacy of gas exchange in the lungs: PaO2, PaO2/FIO2 ratio, arterial PCO2, and gradient between end-tidal and arterial PCO2.

4. Adequacy of systemic oxygenation: Central venous O2 saturation.

SBT FAILURE - SUBJECTIVE

Agitation and anxiety

Depressed mental status

Diaphoresis

Cyanosis

Increased accessory muscle activity

Facial signs of distress

Thoraco-abdominal paradox

Esteban A et alN Engl J Med 1995 Ely EW et al, Am J Respir Crit Care Med 1999

SBT FAILURE - OBJECTIVE

PaO2 < 50–60 mmHg or SaO2 < 90% on FIO2 > 0.5 PaCO2 >50 mmHg or an increase in PaCO2 >8 mmHgpH < 7.32 or a decrease in pH > 0.07 pH units

fR/VT > 105 breaths/min/LfR > 35 breaths/min or increased by >50%

ABG

VENTILATOR

Esteban A et alN Engl J Med 1995: Ely EW et al, Am J Respir Crit Care Med 1999

CARDIOVASCULAR

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

Cardiac arrhythmias

Systolic BP > 180 mm Hg or increased by >20%Systolic BP <90 mm Hg

• A majority of patients (∼80%) who tolerate SBTs for 2 hours can be permanently extubated

• Longer periods of SBTS for patients

with prolonged periods of ventilator dependence (≥3 weeks)

• For patients who fail initial attempts at unassisted breathing daily SBTs.

MacIntyre NR, Cook DJ, Ely EW Jr, et al. Evidence-based guidelines for weaning and discontinuing ventilatory support: a collective task force facilitated by the ACCP, the AARC, and the ACCCM. Chest 2001; 120(Suppl):375S–395S.

NEUROMUSCULAR COMPETENCE

CINMA : Critical Illness NeuroMuscular Abnormalities

CoplinWM, Am J Respir Crit Care Med 2000

Depressed central drive

Encephalitis/ ischemiaMetabolic alkalosis

Sedatives and hypnotics

Peripheral dysfunctionGBS, MG, MND

CINMAVIDD

Drug induced

Critical Illness Neuromuscular Abnormalities (CINMA)

• Most frequent acute polyneuropathy in ICUs• Incidence 30- 58% (80% in MODS, 100% in septic

shock)• Bilateral symmetrical proximal motor deficit• Sensorimotor axonopathy• Limb and respiratory muscle weakness• Strongly associated with failed weaning• Lasts months to years after discharge

Severity of illnessDuration of multiple (≥ 2) organ dysfunction Duration of vasopressor and catecholamine

supportDuration of ICU stay

Hyperglycaemia Female sex

Renal failure and renal replacement therapyHyperosmolality

Parenteral nutritionLow serum albuminNeurological failureAminoglycosides NMB and steroids

Nicola L. Lancet Neurol 2011; 10: 931–41

CINMA BUNDLE

Nicola L. Lancet Neurol 2011; 10: 931–41

ABCDE

Awakening

Breathing

Coordination of awakening/ breathing

Delirium assessment

Early exercise

CRITICAL ILLNESS NEUROMUSCULAR ABNORMALITIESFirst described in Canada and France in 1984.

The reported prevalence of CINMA : 50–100%

Most common peripheral neuromuscular disorders encountered in the ICU setting & usually involve both muscle and nerve.

CINMA is a function of :Severity of illness,Multiple organ dysfunction,Exposure to corticosteroids, Hyperglycemia Prolonged ICU stay

Ventilator Induced Diaphragmatic Damage (VIDD)

Loss of diaphragmatic force-generating capacity related to the use of mech. ventilation

Rapid onset (<18 hrs in animal studies)

Other causes to be ruled out Mechanism

Muscle atrophy Muscle fibre remodelling Oxidative stress Structural injury

Jubran A; Respir Care; 2006Vassilakopoulos T, Petrof BJ; Am J Respir Crit Care Med, 2004

MV 3 d

MV 47 d

• Avoid CMV if possible• Patient Ventilator Synchrony• Adequate nutrition• Avoid steroids if possible –

catabolic effect

“ NAVA : Neurally Adjust Ventilatory Assist”

ORIGINAL ARTICLENeuromuscular dysfunction associated with

delayed weaning from mechanical ventilation in patients with respiratory failure

Yehia Khalil a, Emad El Din Mustafa a, Ahmed Youssef a, Mohamed Hassan Imam b,*, Amni Fathy El Behiry

THE AIM OF THE STUDY:To evaluate the role of the neuromuscular factors responsible for difficult weaning from mechanical ventilation.

Methods: Total of 59 patients with 31 patients having PMV

*Prolonged mechanical ventilation duration ≥ 14 days

Successful weaning: 18 (58%) Failed weaning ( & subsequent death): 13 (42%)

Study period: May 2009 - May 2010.

American Journal of Medicine (2012) 48, 223–232

American Journal of Medicine (2012) 48, 223–232

Corticosteroids intake and neuromuscular dysfunction.

EMG / NCV findings with the outcome and duration of mechanical ventilation

PI max and neuromuscular dysfunctions.

Albumin, Mg, Ca, Ph & neuromuscular dysfunctions.

NUTRITIONAL AND METABOLIC FACTORS

Steroids Myopathy

Glycemic controlInfections

NutritionOverweightMalnutrition

Anemia

Trace elements


ROLE OF ELECTROLYTES

K Mg Ca PO4+ 2+2+ 3-

* Benotti PN, Bistrian B. Metabolic and nutritional aspects of weaning from mechanical ventilation. Crit Care Med 1989; 17:181–185.

** Malloy DW, Dhingra S, Solren F, et al. Hypomagnesemia and respiratory muscle power. Am Rev Respir Dis 1984; 129:427–431

• DAILY T PIECE TRIALS

• PSV SLOW

WEANING • SUCCESSFUL

WEANING

EXTUBATE AND POST

EXTUBATION CARE

• ROLE OF NIV

RE INTUBATION

WHEN REQUIRED

• DAILY SBT• PRESSURE SUPPORT

WEANING

PSV : Pressure Support Ventilation NIV : Non Invasive Ventilation SBT : Spontaneous Breathing Trial

WEANING PROCESS

NEGATIVE TO POSITIVE TRIAD

EXCESSIVE SEDATION

EXCESSIVE ASSIST

PATIENT-VENTILATO

RASYNCHRO

NYPROLONGED MECHANICAL VENTILATION

PATIENT-VENTILATORSYNCHRONY

SPONTANEOUSBREATHING

SEDATIONMANAGEMENT

EARLYWEANING –

3 S

EXTUBATION

Removal of the artificial airway once the mechanical ventilation is not deemed to be necessary

The basics of extubation*• It should never be performed to

reduce the work of breathing

• The work of breathing can actually increase after extubation

* Khamiees M, Raju P, DeGirolamo A, et al. Predictors of extubation outcome in patients who have successfully completed a spontaneous breathing trial. Chest 2001; 120:1262–1270.

The basics of extubation*The increased work of breathing is due to an increased respiratory rate or breathing through a narrowed glottis

The considerations that must be addressed prior to extubation: (a) the patient’s ability to clear secretions from the airways(b) the risk of symptomatic laryngeal edema following extubation.

* Khamiees M, Raju P, DeGirolamo A, et al. Predictors of extubation outcome in patients who have successfully completed a SBT. Chest 2001; 120:1262–1270.

Criteria to define patients at high risk for extubation failure

Nava et al. * Ferrer et al. **Chronic heart failure Age >65 yearsMore than one consecutivefailed weaning trial

Cardiac failureMore than one comorbidity Apache II score >12 at

time of extubationPaCO2 >45mmHg afterextubationWeak cough* Nava SG, Gregoretti C, Fanfulla F, et al. Noninvasive ventilation to prevent respiratory failure after extubation in high-risk patients. Crit Care Med 2005; 33:2465–2470.

** Ferrer M, Valencia M, Nicolas JM, et al. Early non-invasive ventilation averts extubation failure in patients at risk. a randomized trial. Am J Respir Crit Care Med 2006; 173:164–170.

ASSESSMENT BEFORE EXTUBATION• Alertness and muscle function - Ability to

lift the head off of the bed for 5 seconds • Adequate cough reflex (must not require

suctioning more than every 2 hours)• Adequate airway patency - CUFF LEAK

TEST

MacIntyre NR. Evidence-based guidelines for weaning and discontinuing ventilatory support: a collective task force. Chest 2001; 120(Suppl): 375S–395S

Airway Protective Reflexes Protection determined by the strength of the gag

and cough reflexes.

Cough strength: “ Hold a piece of paper 1–2 cm from the end of the endotracheal tube and asking the patient to cough. If wetness appears on the paper, the cough strength is considered adequate.”

*Diminished strength/absence of cough/gag reflexes will not necessarily prevent extubation, but identifies patients who need prevention from aspiration.

Bach JR, Saporito LR. Criteria for extubation and tracheostomy tube removal for patients with ventilatory failure: a different approach to weaning. Chest 1996; 110:1566 –1571

Post Extubation Laryngeal Edema (PELE)

• Upper airway obstruction from laryngeal edema is the major cause of failed extubation

• Reported in 5–22% of patients who have been intubated for longer than 36 hours.

• Contributing factors include difficult & prolonged intubation, endotracheal tube diameter, and self-extubation.

*Jaber S, Chanques G, Matecki S, et al. Post-extubation stridor in intensive care unit patients. Risk factors evaluation and importance of the cuff test. Intensive Care Med 2003; 29:63–74.

The Cuff-Leak Test

The volume of inhaled gas that escapes through the larynx when the cuff on the ET tube is deflated.

Designed to determine the risk of symptomatic upper airway obstruction from laryngeal edema after the endotracheal tube is removed.

Absence of air leak: High risk of upper airway obstruction following

Extubation

INTERPRETATION• An air leak does not indicate a low risk of

upper airway obstruction following extubation, regardless of the volume of leak.

• Leak of less than 110 mL or 10 – 15% ?• The test is not universally accepted. Results

of a cuff leak test do not alter patient management

• Clinical relevance of the test is unproven.

REINTUBATION PARAMETERS• RR > 25 breaths/min for 2 hrs• HR > 140 beats/min or sustained increase or

decrease of >20%• Clinical signs of respiratory muscle fatigue or

increased work of breathing• SaO2 < 90%; PaO2 <60 mmHg on FIO2 >0.50• Hypercapnia (PaCO2 >45 mmHg or >20% from pre-

extubation), pH <7.32

Fernando Frutos-Vivar,et al Chest 2006

Pretreatment with Steroids?

Pretreatment with intravenous corticosteroids :

IV methylprednisolone, 20–40 mg every 4–6 hrs

Duration: 12 to 24 hours prior to extubation

Khamiees M, Raju P, DeGirolamo A, et al. Predictors of extubation outcome in patients who have successfully completed a spontaneous breathing trial. Chest 2001; 120:1262–1270.

• Brief period (12 to 24 hrs) of steroid therapy prior to planned extubations, (in patients with high risk of post-extubation laryngeal edema)

• A single dose of methylprednisolone (40 mg IV) given 1 hour prior to extubation did not reduce the incidence of post-extubation laryngeal edema

• Thus there is no reason to administer steroids only at the time of extubation.

Postextubation Stridor

The first sign of a significant laryngeal obstruction

High-pitched and wheezy, inspiratory prominence

Reintubation is not always required

No proven method for reducing laryngeal edema after extubation.

Aerosolized Epinephrine• Inhalation of aerosolised epinephrine (2.5 mL

of 1% epinephrine) • Practice is unproven in adults. • Found to be effective in children• No advantage with racemic epinephrine over

standard (l-isomer) epinephrine

Noninvasive Ventilation

• Effective in reducing the rate of reintubation when used immediately after extubation in patients with a high risk of laryngeal edema

• No benefit in patients who develop post-extubation respiratory failure.

• Benefit of NIV ventilation occurs when it is used as a preventive measure early after extubation.

OTHER MODES OF VENTILATION

• NAVA (Neurally Adjusted Ventilatory Assist )

• Automatic Tube Compensation

• Proportional Assist Ventilation

• Adaptive Support Ventilation

Neurally Adjust Ventilatory Assist (NAVA)

CNS

Phrenic nerve

Diaphragm excitation

Diaphragm contraction

Chest wall, lung & esophageal response

Airway pressure, flow, volumeCURREN

T

IDEAL

NAVA

NAVA Electrical activity of the diaphragm - Eadi

Represents the patient's breathing effort Normal healthy adults EAdi < 10 uV Can assess : Respiratory drive Synchrony Unloading of respiratory muscles

Sinderby C, Nat Med 1999

ADAPTIVE SUPPORT VENTILATION (ASV)

Advantages Provides Automated weaning Fewer human resources are needed at bedside

No triggerPCV Spont < Target

PS/SIMV

Spont> TargetPSV

Respiratory Rate

ROLE OF NIV

• Early weaning – failed SBT• After conventional weaning

to prevent post extubation failure

• Respiratory failure post extubation

R Chawla et al: Ind J Crit Care Med 2006

ROLE OF TRACHEOSTOMY

ADVANTAGESImproved pt comfort

Effective airway suctioning

Dec. airway resistance

Reduced dead spaceEnhanced pt mobility

Improved speechAbility to eat orally

DISADVANTAGES

Perioperative complications

Late tracheal stenosisObstruction

Impaired swallowing

JE Heffner : Chest 2001; 120:477S– 481S

COMMON MISCONCEPTIONS ABOUT TRACHEOSTOMY

Early tracheostomy does not reduce the incidence of VAP

Early tracheostomy does not reduce mortality rate.

Early tracheostomy reduces sedative requirements and promote early mobilization

BEST TIME FOR TRACHEOSTOMY 7-14 DAYSTerragni et al. Early vs. late tracheotomy for prevention of pneumonia in mechanically ventilated adult ICU patients. JAMA 2010; 303:1483– 1489

Liberate from ventilation

SBT in any form Sedation,synchrony,

spontaneous breathing Daily SBT and PSV

equally effective, SIMV least efficient for weaning

Mechanical ventilation for > 2 weeks : early tracheostomy

TAKE HOME MESSAGE

Special thanks to:

Dr Gyaninder Pal Singh, Asst ProfessorDepartment of Neuroanaesthesia

Dr Karan Madan, Asst Professor,Department of Pulmonary Medicine

Dr Kavitha, Senior Resident Department of Pulmonary Medicine

Dr Sryma Punjadath, Junior ResidentDepartment of Internal Medicine

HAPPY NEW YEAR

weaning from mechanical ventilation

Health & Medicine