Dr. Shelly Zubert FRCPC Emergency Medicine Fellow Critical Care Medicine Jan 17 – Jan 31, 2011 University of Manitoba Canada Liberation from Mechanical Ventilation

Define Liberation terms Review Chest Guidelines for liberation Discuss approach to Liberation decision making ……. In 30 minutes Objectives

Simple Weaning –Proceed from SBT to successful extubation on FIRST attempt –70% Difficult Weaning –Fails initial weaning –Requires 3 or less SBTs or up to 7 days from first SBT to achieve successful weaning Prolonged Weaning Classification of Weaning Patients Brochard 2005 Boles JM et al. Weaning from mechanical ventilation. Eur Respir J 2007; 29: ~5% I CU Mortality 25% ICU Mortality

Vital Capacity > 10 mL/kg Minute ventilation < 10 L/min Maximum voluntary ventilation > 2X V E Maximum inspiratory force > 30 cm H 2 0 Traditional Weaning Criteria Sahn and Lakshminaraayan Chest 1973; 63:1002

VC, Minute Ventilation, MIP Sahn and Lakshminarayan Chest 1973 f/VT (frequency / Tidal Volume (L)) or RSBI (Rapid Shallow Breathing Index) Yang & Tobin NEJM 1991; 324: Most Commonly Used Weaning Parameters

Review Chest 120 (6) Dec 2001, 375S-395S Evidence Based Guidelines Weaning and Discontinuing Ventilation

In all patients requiring > 24 hours of mechanical ventilation –Search for all causes contributing to ventilator dependence –Reversal of all ventilatory and nonventilatory issues preventing successful extubation Recommendation 1

7 Stages of Weaning Boles JM et al. Eur Respir J 2007; 29:

Respiratory Mechanics –Weakness, Muscle atrophy due to inactivity –Muscle damage Ciritical illness neuropathy / myopathy –Toxins NM Blockers, Steroids, Aminoglycosidesd –Dynamic Hyperinflation –Inappropriate ventilator settings Ventilator Dependance

Cardiovascular physiology Physiological changes associated with mechanical ventilation discontinuation: –Increased metabolic demands –Increased venous return from diaphragm contraction –Increased afterload from negative pleural pressure swings Ventilator Dependence

Neurological / Neuromuscular Issues –Structural Abnormalities Stroke –Physiology Abnormalities Central Sleep Apnea –Metabolic (electrolytes, endocrinopathy) –Peripheral nerves (structural / metabolic) –Delerium –Sedatives Ventilator Dependence

Metabolic / Nutritional Factors –Malnutrition – protein catabolism and loss of muscle performance –Overfeeding – excess CO2 production –Electrolyte deficiency Magnesium, Phosphate –Endocrine Hypothyroidism, adrenal insufficiency, insulin Ventilator Dependence

Mechanically ventilated patients should be formally assessed for extubation when: –Underlying cause has improved No distress –PaO2/FiO2 > ; PEEP 7.25 –Hemodynamic stability achieved No Myocardial ischemia Low dose vasopressors –Ability to breathe spontaneously Recommendation 2 Chest 2001; 120(6supp) and Respir Care 2002 (Jan); 47(1): 69-90

SBT (Spontaneous Breathing Trial) –Should be done on spontaneous modes of breathing –A patient that has a successful initial assessment over 1-3 minutes should be considered for a formal SBT –Formal SBT should be 30 – 120 minutes Recommendation 3

SBT (Spontaneous Breathing Trial) –Brief initial assessment 1-3 minutes Measure respiratory rate and Tidal volume Calculate f/VT –F/VT < 106 should be considered for formal SBT –Formal SBT minutes –PSV Pressure 0 and PEEP 0 –PSV Pressure 6 and PEEP 5 –CPAP Pressure 5 –T piece trial –Final Test - Extubation Approach to Extubation Tobin MJ et al. ICM 2006; 32(12):

Assessed by SBT Oxygenation Ventilation Not assessed by SBT Airway protection Secretion Clearance 4 Elements in Respiratory Failure

Screening for Formal SBT –PaO2 / FiO2 > 200 –PEEP < 6 –Adequate cough with suctioning –F/VT < 106 after 60 sec SBT –No vasopressor or sedatives Dopamine 5 mcg/kg/min acceptable Identification of Extubatable patients Ely et al. NEJM 1996; 335:

Termination criteria for SBT –Respiratory Rate > 35 –SaO2 < 90% –HR > 140 or sustained 20% change from baseline –Systolic BP > 180 or < 90 –Increased anxiety –Diaphoresis Identification of Extubatable patients Ely et al. NEJM 1996; 335:

??? Ready to Extubate ???

Extubation should be sought providing the following 2 criteria can be met: –Airway patency expected post extubation –Airway protection expected Recommendation 4

Cough Strength –Peak cough flow –White card test Amount of endotracheal secretions –Frequency of suctioning –Volume of secretions Mental status PCO2 prior to extubation Clinically Predicting Extubation Failure

Leak Test –Identifies patients at risk for stridor Chest 1996; 110: Peak cough flows>160 L/min –Neuromuscular or Spinal Cord injured patients Bach et al. Chest 1996; 110: SBT –Successful extubation in Brain injury patients Coplin et al. Am J Respir CCM 200; 161:1530 Am J Respir CCM 2001; 163:658 Evidence Based Extubation Failure Evidence Grade C

Replacement of Endotracheal tube –Within 48 hours –Approximately 10-20% of extubations Mechanisms of Failure –Imbalance between muscle capacity and mechanical load –Upper airway obstruction –Inability to clear secretions Complications: –Increased mortality, Length of stay, pneumonia Failed Extubation

Prediction Rule for Extubation Failure Mokhlesi et al. Respir Care 2007; 52(12); 1710

Patients that fail a SBT –Identify and treat reversible causes –Patients should be on controlled mode of ventilation until reversib le causes addressed –Then repeat SBTs every 24 hours with goal of extubation as early as possible Recommendation 5

Search for reversible causes before attempting to wean again: –Pain control –Sedation appropriateness –Fluid status –Control of myocardial ischemia –Bronchodilator needs –Presence of other disease process Failed SBT Evidence Grade A

For the failed SBT patient –Should receive a stable, non-fatiguing and comfortable form of ventilatory support Goals for the next 24 hours: –Maintain adequate muscle unloading Assisted modes of ventilation preferred –Optimize comfort and sedation needs –Avoid complications –Do Not aggressively reduce ventilatory support Recommendation 6

546 Patients Large Randomized Control Trial SBT vs PSV vs (S)IMV SBT every day results in shorter times to extubation SBT versus Traditional Methods Esteban et al. NEJM 1995; 332:

Extubation protocols should be developed –Robertson et al. Critical Care Medicine 2008: 35; 2753 Recommendation 7

A Daily Approach

Studies –Girault et al. Noninvasive ventilation as a systematic extubation and weaning technique in acute-on –chronic respiratory failure. Am J Respir CCM 1999; 160(1); 1645 –Nava et al. Noninvasive mechanical ventilation in the weaning of patients with respiratory failure due to COPD. Ann Intern Med 1998; 128(9): –Ferrer et al. Noninvasive ventilation during persistent weaning failure. Am J respir CCM 2003; 168: 70 –Esteban et al. Noninvasive Positive Pressure Ventilation for Respiratory Failure after extubation. NEJM 2004 Weaning with NPPV

Manthous et al. Liberation from mechanical venilation. Chest 1998; 114: Esteban et al. Clinical management of weaning from mechanical ventilation. Int Care Med 1998; 24(10); 991 Tobin MJ. Remembrance of weaning past: the seminal papers. Int Care Med 2006; ;Oct 32(10): Classic Review Articles

Tobin, Mark and Jubran, Amal et al. Weaning from mechanical Ventilation Ch 58 Tobin’s textbook. Boles et al. Weaning from mechanical ventilation. Eur Respir J 2007; 29: Epstein SK et al. Weaning from ventilatory support. Curr Opin Crit Care 2009; 15:36-43 Recent Review Articles

Questions?