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Difficult Weaning An approach Ram E. Rajagopalan, MBBS, AB (Int Med) AB (Crit Care) Head, Department of Critical Care Medicine SUNDARAM MEDICAL FOUNDATION.

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Presentation on theme: "Difficult Weaning An approach Ram E. Rajagopalan, MBBS, AB (Int Med) AB (Crit Care) Head, Department of Critical Care Medicine SUNDARAM MEDICAL FOUNDATION."— Presentation transcript:

1 Difficult Weaning An approach Ram E. Rajagopalan, MBBS, AB (Int Med) AB (Crit Care) Head, Department of Critical Care Medicine SUNDARAM MEDICAL FOUNDATION Chennai

2 Goals of this talk To define “difficult” wean Evaluate the pathophysiology of ventilator dependence Identify difficult-to-wean groups Consider a systematic approach to minimising reversible causes of ventilator dependence Consider methods to enhance wean Not an evaluation of long-term ventilator dependence

3 What is weaning? “Discontinuation”; the apolitical term It starts when the doctor decides that the disease has resolved & patient is “ready” for  support Objective “readiness” criteria:  Adequate oxygenation (P/F > 200, PEEP<5)  Stable CVS (BP, ’pressors, HR)  Adequate cough reflex  Adequate mentation (GCS>12)  ? Rapid-shallow breathing index <100 Chest 2001; 120:375S–395S

4 Initial Trial of Discontinuation When patients are “ready” to wean, a spontaneous breathing trial (SBT; using a T-piece for 2 hours) is tolerated by most. Re-intubation rates average~15% Abbreviation to a 30-min SBT reduces ICU & Hospital LOS* AJRCCM 1994; 150: N Engl J Med 1995; 332: *AJRCCM 1999;159:

5 All attempts are NOT likely to succeed!!

6 Spanish Collaborative Trial Approach to the failed SBT N Engl J Med 1995;332;

7 Summary Approach The Failed SBT After return to MV, patients should undergo a daily 2-hour T-piece trial PS(7 cm H 2 0) + PEEP is acceptable IMV should NOT be used AJRCCM 1994; 150: N Engl J Med 1995; 332;

8 “Weaning” vs. “Extubation” Success Success with and SBT / RSBI is Neither specific (false +ve; fail extubation) 15% re-intubation rate Nor sensitive (False –ve; prolonged vent) Difficult to study Extrapolate from spontaneous extubation High success even after failed tests

9 Defining “Difficult-to-wean” “Ready to wean” 2/3 extubated (15% reintubation) Initial T-piece SBT 1/3 fail Daily SBT/ Pres. Sup 85-90% weaned in 14 days “Prolonged Ventilation” AJRCCM 2001; 164: * Chest 2005; 128: * Eur Respir J 2007; 29: Consensus Definitions* “Difficult Wean” In acute cases ~25-40 % & need ~ 7days & 3 SBTs “Prolonged Wean” Up to 14 days (~10%) “Prolonged Mechanical Ventilation” (PMV) is the need of MV >21 days for >6 hours /day; 3-7% Mortality / Resource use

10 Weaning Difficulty & Outcome Frequency Re-intubation Mortality AJRCCM; 2013: 187; ■Simple ■Difficult ■Prolonged

11 Pathophysiology N Engl J Med 2001; 344: Chest 2001; 120:375S–395S Rapid shallow breathing ? Response to inadequate drive / breath ? Inappropriate response to increased load

12 Pathophysiology Rapid shallow breathing (  RR  in COPD) Increased respiratory load  Higher PEEPi  Higher Elastance  Higher Resistance Maintained neuromuscular drive (P 0.1 )* Reduced muscle strength (Pdi max )* Imbalance between load & capacity Higher PCO 2 Similar in COPD and post-CTS* Not predictable by baseline mechanics * AJRCCM 2000;161: 1115–23.

13 Effect of weaning on CV Spontaneous breathing  intrathoracic pressure ( insp. Swings) Venous return Unmasks LV Diastolic Dysfunction Pulmonary edema Venous desaturation Hypoxia Pulmonary hypertension RV Failure Anesthesiology 1988; 69:171–179 AJRCCM 1998;158:1763–1769. Chest 2001; 120:375S–395S

14 Reversible Factors Improve neuromuscular competence Treat Sepsis Nutritional support without overfeeding Replace K, Mg, P to normal Assure periods of respiratory muscle rest; avoid exhausting breathing trials Limit use of neuromuscular blocking drugs Consider stopping aminoglycoside therapy Consider Neurological disease Hypothyroidism Over sedation Critical illness myopathy / polyneuropathy Steroid myopathy Investigational / unproven Anabolic Steroids Growth Hormone Aminophylline Reduce respiratory load ResistanceBronchodilators Corticosteroids Removal of airway secretions Treatment of upper airway/ET obstruction ComplianceTreat Pneumonia Treat pulmonary oedema Reduce intrinsic PEEP Drain large pleural effusions Evacuate pneumothoraces Treat Ileus Decompress abdominal distension VeTreat sepsis Antipyretics Avoid overfeeding Correct Metabolic acidosis Reduce intrinsic PEEP Bronchodilators Maintain least PEEP possible Resuscitate shock and hypovolemia Identify and treat pulmonary embolism A (c)heck list !! From: Chest 1998; 114: I think you are stupid if you still want to read the whole list!

15 Risk Factors: Influence of Aetiology f/Vt <100; MIP < hour T-piece trial COPD 39% weaned AJRCCM 1998; 158: % weaned NEURO 62% weaned Ac. Resp. Failure

16 Influence of Aetiology f/Vt <100; MIP < hour T-piece trial COPD 39% weaned 36% re-intubated Low GCS 9% re-intubated 59% weaned NEURO 62% weaned Ac. Resp. Failure AJRCCM 1998; 158:

17 Weaning Risk; Co-morbidity AJRCCM 2003; 167: A458 Chest 2005; 128: >1400 patients in 23 LTC facilities Mean age =72 years High frequency of associated co-morbidity COPD, CAD & Neurological Dx Renal failure; 1.9X probability of failed wean GCS <8 ; 6.5X probability of weaning failure

18 Other Risk Factors Age >65; comorbidity APACHE Score Neurological failure COPD / Secretions / Feeding (CO 2 retention at SBT) Respiratory failure of Cardiac Origin ( BNP /  ScvO2 at wean) Critical Illness Polyneuropathy Nutrition

19 Neurological Function Neurological drive is well preserved in most difficult-to-wean patients Drive may be suppressed by  CVA  Non-convulsive seizures  Electrolyte disturbance (Low Na)  Medication (sedatives)  Hypothyroidism (+ impairs muscle fn.)

20 Sedation: Daily Discontinuation Routine Sedation Daily d/c RCT; 128 adults on ventilation N Engl J Med 2000;342: “Wake-up” call

21 PMV & Hypothyroidism 140 patients with PMV (routine screen) 1 old hypothyroid TSH  in 16 (12.1%) TSH  +  T 3 / T 4 = 4 (3%) Clinical suspicion, BMI are poor correlates. Hypothyroidism is a rare but treatable cause of PMV Chest 2004; 126:

22 Predictors of Wean Aetiology matters COPD / ARF  Duration of ventilation  Age  f / Vt ratio  P 0.1  MIP Neurology  MIP  MEP  f / Vt. P 0.1 AJRCCM 1998; 158:

23 Cardiovascular Reserve Weaning causes significant changes in LV & RV function Consider occult coronary disease  Beta blockade? Optimise function  Weight loss associated with diuresis correlates with wean in PMV*  My bias towards nitrates  Dobutamine unlikely to be beneficial  Inodilators (enoximone) used effectively in CVTS * AJRCCM 1992; 145: A522

24 Fluid Restriction (FACTT) N Engl J Med 2006;354: Achieved 7-day fluid balance of ml (conservative) vs ml  Pplat & oxygenation index ________________________________________ Expected  in ’lytes __________________________________________ 2 day vent-free & ICU-free days (p <0.001) ______________________________________________ No  in mortality

25 S v O 2 monitoring in wean AJRCCM 1998; 158: Venous desaturation was significantly  in patients who fail weaning (SBT) AROC: 0.70 ± 0.08 PaOP and plasma protein conc. have value? AROC= 0.93 ± 0.04 Critical Care 2010; 14: 211

26 Weaning Failure Basal measurement of E/E’ has been validated as a marker of weaning failure in multiple studies; Lamia; E/E’ >8.5 with E/A.0.95; Sens 82% Spec 91% Papanickolaou E/E’ >7.8 Sens 79% Spec 100% ICM 2011; 37: CCM 2009; 37:

27 Weaning Failure & Diastolic Dysfunction Moschietto et al. Critical Care 2012, 16:R81 68 unselected pts. 28 fail wean Weaning failure if: Basal E/E’ >12.6 (AUC.75) 10min SBT E/E’ >14.5 (AUC.86) Or E’ <8 at baseline Basal E/E’ 10 min E/E’ 1-specificity Sensitivity

28 Implications on Weaning Identification prior to / early in SBT gives room for preventive care If identified; attention to fluid management may enhance weanability May identify a role for NIV / CPAP after extubation

29 BNP- directed wean RCT of BNP to guide fluid Rx (n=304) 15% CAD 25% COPD 60% neither Avg. P/F = 210 Larger -ve balance (-2.3L vs -0.1 L) Wean time  ; 42 hr. vs. 58 hr. AJRCCM 2012: 186; *Critical Care 2010; 14: 211 BNP with failed SBT (AROC ) Cut-off of 275 pg/ml Questionable incremental value*

30 Respiratory Load Remember: rapid shallow breathing is effective for energy utilisation but affects lung mechanics Increased resistance and elasatance occurs in most difficult weans Minimising load is useful: Lower Ve  Sepsis  Fever  Overfeeding

31 OVERFEEDING CHO:FAT VCO 2 LUNG DISEASE COPD PCO 2 WEAN FROM VENTILATOR Nutrition & Respiratory Load

32 Overfeeding & Respiratory Load VCO 2 is affected more by hypercaloric feeding than by the carbohydrate: fat ratio Chest 1992;102:551-5

33 ARDSnet:  -3 Fatty Acids JAMA 2011; 306:

34 Motor Function Muscle weakness may be a reversible contributor to ventilator dependence Identify & Rx: Electrolyte problems:  Deficiency of K, Mg, P Identify: Critical Illness Polyneuropathy Stop: neuromuscular blocking agents Stop: aminoglycosides Stop: steroids?

35 Hypophosphatemia Causes are multifactorial Refeeding Syndrome (associated hypo K and hypo Mg) Respiratory Alkalosis / correction of respiratory acidosis Met. alkalosis causes smaller change Sucralfate Used for stress ulcer prophylaxis CCM 1989; 17: CC Clin 1991; 7: P repletion improves Pdi

36 Critical Illness Polyneuropathy In one study 96% of patients ventilated >7 days Had EMG/ Biopsy evidence of neuro/myopathy 62% with similar findings in PMV Sepsis may contribute to CIPN Use of steroids, NMB agents of importance in myopathy…..

37 Glycemic Control (Crit Care Med 2003; 31: ) The dose-response relationship: k

38 Chest 2007; 132: Cochr Databa of Sys. Rev. 2014, DOI: / CD pub3. Despite recent controversy on the value of strict glycaemic control in medical patients Effect on CIPN seems consistent…. Meta-analysis RR: 0.65 (95% CI; )

39 NIV: To Hasten Wean p <0.01 p 0.02 Ann Int Med 1998; 128: In COPD patients; 60-day mortality & nosocomial pneumonia show improving trends Strategy #1

40 COPD: NIV weaning p 0.10 p 0.06 NIV wean is NOT an established strategy in ventilated patients with other aetiologies Ann Int Med 1998; 128: Chest 2001; 120: 438S-44S Ferrer; AJRCCM 2003;168:70–76

41 NIV: To prevent Re-intubation Effective when used prophylactically in selected cases post-extubation;  COPD  Elderly >65  High APACHE  APE as cause  PCO 2 at SBT Sampath S, ESICM abstract 2007 The use of NIV in patients extubated after failing SBT has no value. AJRCCM 2011; 184:

42 PS vs. T-piece in SBT p = 0.02 The “spurious”* belief that work of breathing with an ETT and  consistently on extubation No difference in LOS, mortality. 63% of T-pieced and 70% of PS patients remained extubated (NS) AJRCCM 1997; 156: *AJRCCM 2012; 185: Strategy #2

43 PS vs. T-Piece in SBT Wean with low PS may result in false +ve SBT pass In COPD & LVF where extubation is to NIV prefer SBT on CPAP alone (over low PS); may perform better In all other cases T-piece is preferred to estimate success more accurately

44 Tracheostomy? Chest 2001; 120:477S–481S Improved comfort of caregiver (Doctor / nurse vs. patient) Airway mechanics  Less Resistance  Increased turbulence ? benefit on wean duration Strategy #3

45 Is there evidence? 5 RCT studies identified 406 patientsDefn. Bouderka 2004, n=625-6 d Dunham 1984, n=743-4 d Rodriguez 1990, n= d Rumbak 2004, n=120<2 d Saffle 2002, n=44ASAP BMJ 2005; 330: 1243

46 Weaning From Ventilation BMJ 2005; 330: fewer days on ventilator No VAP or mortality difference

47 Recent Tracheostomy RCTs *JAMA 2010; 303: **JAMA 2013;309: Italian* TRACMAN** (Terragni et al) Early LateEarly Late N Day of trache % trached69% 57% 92% 45% MortalityNo differenceNo difference VAPHR: 0.66; NSN/A ICU LOS  ; HR: 0.73 ( )13 days; NS Ventilation duration  ; HR: 0.70 ( )N/A

48 Tracheostomy in India Context-specific differences: High rates of VAP  compliance oral antisepsis with ETT Trache may  VAP more than in the west Very poor patient mobilization with ETT Trache facilitates physiotherapy…….

49 Physical Therapy in ICU Strategy #4 104 patients <72 hours since ICU admit Expected ventilation >24 hrs Control: 55; Sedation interrupt Activity per doctor’s order 35% 21 days 49; Treatment Sedation interrupt Planned graded PT/OT 59% 23.5 days Independent at discharge OR: 2.7 ( ) p=0.05 Ventilator-free days

50 Protocols: ( C)lean, Mean Guarantees of Success? Does the application of nurse/ respiratory care professional directed weaning trial improve outcome? Removes uncertainty and delays involved with physician-centred decisions. Strategy #5

51 Simple Wean by Protocol N Engl J Med 1996; 335: patients randomised Adjusted RR of extubation with Protocol was 2.13 (95% CI = ) Re-intubation was less frequent: 4% vs. 10% (p 0.04) Cost of ICU care was lower (p 0.03) Similar outcomes reported by Kollef et al. (Crit Care Med 1997; 25: )

52 Protocols in difficult wean COPD >15 days ventilation 55 “protocol” weans vs. 62 historical controls Low quality evidence AJRCCM 2001;164: Weaned

53 Summary Chest 2001; 120: 425S-437S Care of the difficult-to-wean patient consumes resources Identification of high-risk groups can allow better allocation of these resources Identification and correction of reversible co-morbidity is essential to enhance wean Logical ventilatory strategies may improve success


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