Weaning Process

LIBERATIONJudgement CallDr Ikhwan bin Wan Mohd Rubi, MD (UKM)

Supervisor:Dr Mohd Ridhwan Mohd NoorOutlineIntroductionWeaning and its evolutionClassification of weaningPrinciples, Assessment; Clinical and ObjectivesSpontaneous Breathing TrialApproach, protocol, criteria to passExtubation, failed extubationRole of NIV & also tracheostomyCauses of failed SBTAlgorithm of weaning

IntroductionMV is the defining event in ICU mxA life saving intervention in acute resp failure and other disease entitiesThe aim of ventilatory support is to unload the patients respiratory pump

Why Wean early ??? Increased risk of VAPIncreased ICU length of stayIncreased hospital length of stayIncreased morbidity & mortalityIncreased costDecreases the availability of ICU bedsCan adversely affect the patient outcomeMajor goal is actually to LIBERATE pts from MV as early as possible while AVOIDING premature weaningComplication of prolonged MV

Premature weaning carries its own set of problems, including difficulty in re-establishing artificial airway, compromised gas exchange, high incidence of nosocomial pneumonia and 6 to 12 fold increased mortality risk.

4WeaningDef: A process of transition/gradual withdrawal of MV support that transfers the WOB from ventilator to the patientRemoval of a necessary (short term) but potentially damaging (prolonged) intervention as early as feasible

This period may take many forms ranging from abrupt to gradual withdrawal from ventilatory support

Goal is to facilitate effective spontaneous breathing while reducing ventilatory support

BALANCE between reducing ventilatory support without increasing pts WOB to the point of fatigue and failure

The process of reloading the respiratory pump

Weaning

Adequate ventilatory support(minimizing respiratory fatigue)Minimizing support (increasing pts resp autonomy)Not over assisting, but not to cause fatigueEvolution of Weaning>than a decade ago, weaning from PPV was often a slow gradual process of reduction in ventilatory support (IMV)Introduction of SIMV mode and later PSVNumerous studies have investigated methods and tools for identifying readiness of mechanically ventilated pts for successful liberation from MV Facts75% of mechanically ventilated patients are easy to be weaned off the ventilator with simple process;Hall JB, Wood LDH: Liberation of the patient from mechanical ventilation, JAMA 1987, 257: 1621-1628

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

5-10% require a gradual weaning over longer time

1% of patients become chronically dependent on ventilator

Hall and Wood ultimate purpose is not wean but rather liberation9Classification of Weaning

Group/ categoryDefinitionSimple weaning Patients who proceed from initiation of weaning to successful extubation on the first attempt without difficulty

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

Prolonged weaning Patients who fail at least three weaning attempts or require >7 days of weaningafter the first SBT

Classification of Patients According to the Weaning ProcessGroupDefinitionFrequencyICU mortalityHospital mortality(1)Simple weaningPatients who proceed from initiation of weaning to successful extubation on the first attempt without difficulty

69%5%12%(2) Difficult weaningPatients who fail initial weaning and require up to three SBT or as long as 7 days from the first SBT to achieve successful weaning

16%25%(3) Prolonged weaningPatients who fail at least three weaning attempts or require 7 days of weaning after the first SBT

15%Boles, et al. Eur Respir J 2007Principles

In ShortConsider weaning ASAPConsider weaning once underlying causes resolved/improvedEvaluate early & at least dailyCNS/CVS/Resp(patency/protection) must intact before extubationMinimize/discontinue sedation for daytime SBTUNLESS in irreversible underlying disease

When to begin the weaning process?Numerous trials performed to develop criteria for success weaning, however, not useful to predict when to begin the weaning Physicians must rely on clinical judgementConsider when the reason for IPPV is stabilised and the patient is improving and haemodynamically stableDaily screening may reduce the duration of MV and ICU costSchematic Representation of the Different Stages Occurring in aMechanically Ventilated Patient

Definition of the different stages, from initiation to mechanical ventilation to weaningStagesDefinitionsTreatment of ARFPeriod of care and resolution of the disorder that caused respiratory failure and prompted mechanical ventilationSuspicionThe point at which the clinician suspects the patient may be ready to begin the weaning processAssessing readiness to weanDaily testing of physiological measures of readiness for weaning (NIF, fR/VT) to determine probability of weaning successSpontaneous breathing trialAssessment of the patients ability to breathe spontaneouslyExtubationRemoval of the endotracheal tubeReintubation

Replacement of the endotracheal tube for patients who are unable to sustain spontaneous ventilationMartin J. Tobin2001

Protocol Weaning is More Effective than No Protocol

Numerous studies have demonstrated that protocol weaning decreases mechanical ventilation days.Vitacca AJRCCM 2001;164:225-30 Henneman CCM 2001;29:297-03 Kollef New Horizons 1998;6:52-60 Kollef CCM 1997;25:567-74 All studies utilized a daily screening and subsequent spontaneous breathing trial to test the patients potential for discontinuing mechanical ventilation. Compared with usual care, use of weaning protocols can reduce the duration of mechanical ventilation by 25% weaning duration by 78% length of stay in intensive care unit by 10%

Assessment of readiness to weanA Daily routine follow up should be done in every patient receiving mechanical ventilation and exploring the following condition

Clinical assessmentObjective measuresRespiratory criteriaCardiovascular criteriaNeurological criteria

Clinical AssessmentResolution of acute phase of disease for which patient was intubated; indication of mechanical ventilation is reversedAdequate cough (subjective)Absence of excessive tracheobronchial secretion; frequency of trachea suctioning; characteristic of secretioncough-white card test to assess adequate cough objectivelyFrequent if hourly or less suctioningCharacteristic- loose or thick19Objective measuresRespiratory criteria (O2 and ventilation)Adequate O2; PaO260mmHg on FiO20.5 & PEEP8cmH2ONo significant respiratory acidosis; pH and PaCO2 appropriate for patients baseline respiratory statusRR 5mls/kgMV