Ventilator Weaning

See Also

Pathophysiology

Ventilated for less than 2 weeks
1. Respiratory Muscles do not decondition significantly
2. Exceptions
  1. Comorbid condition or
  2. Severe increased VO2 with negative nitrogen balance
Majority of patients do not need Ventilator Weaning
1. Either need the Ventilator or they do not

Indications
Weaning

Prolonged debilitated state, deconditioning or weakness
Chronic Obstructive Pulmonary Disease
Severe Congestive Heart Failure
Catabolic State
1. Results from high dose Corticosteroids
2. Results in weak chest Muscles

Risk Factors
Reintubation after Extubation

Age >65 years
APACHE Score (v2) >12
BMI >30 kg/m2
Inadequate clearance of secretions
Difficult or prolonged Ventilator Weaning
Intubation indication for CHF or COPD
Prolonged Mechanical Ventilation

Management
Preparation for weaning - Nutritional Status

Early nutritionist Consultation
Low Carbohydrate Diet if increased VCo2
Avoid negative nitrogen balance
Use a working GI Tract to provide early nutrition
1. Place Dobbhoff NG tube (check placement with XRay)
2. Select a supplement (e.g. FS Pulmocare)
3. Measure q4 hour Residual Volumes
  1. Consider prokinetic agent for >50 cc residuals
    1. Metoclopramide (Reglan) 10 mg PO qid
    2. Erythromycin 250 to 500 mg PO qid

Management
Preparation for weaning - Pulmonary Status

Maximize bronchodilation if bronchospasm
1. Consider Inhaled Corticosteroids over systemic
Avoid Respiratory Acidosis
1. Adjust pCO2 to premorbid level

Management
Preparation for weaning - Psychosocial Status

Alleviate anxiety
Reassure of support
Encourage optimism. and discourage discouragement
Try not to convey frustration

Management
Preparation for weaning - Cardiac Status

Coronary Artery Disease
1. Consider Anti-Anginal medications (Nitroglycerin)
2. Check Electrocardiogram
  1. Baseline
  2. After a failed weaning trial
Congestive Heart Failure
1. Maximize volume status
2. Reduce Afterload
3. Use inotropic agents as needed (Dopamine, Dobutamine)

Management
Preparation for Weaning - Sedation

Hold benodiazepines (use only prn)
Decrease Propofol and Fentanyl rates every 4 hours
Consider Dexmedetomidine (Precedex)

Management
Spontaneous Breathing Trial (SBT)

Assess readiness for Extubation on a daily basis
1. Daily interruption of continuous sedation (to RASS of 1)
2. "Wake up and breath protocol" for trial of Ventilator Weaning
3. Khan (2014) Crit Care Med 42(12):e791-5 +PMID: 25402299 [PubMed]
Indications: Spontaneous Breathing Trial (SBT) Readiness
1. Are there unstable confounding factors that contraindicate a trial?
  1. Unstable cardiovascular status?
  2. Unstable medical comorbidity?
  3. Has the primary indication for Endotracheal Intubation and ventilation resolved?
  4. Excessive airway secretions?
2. Does patient awaken sufficiently?
  1. Cooperative?
  2. Able to follow commands?
  3. Able to initiate breaths?
  4. Does patient protect their airway?
  5. Adequate Gag Reflex?
  6. Good cough?
3. Is oxygenation adequate?
  1. PaO2/FIO2 >150-200
  2. PEEP <3-5 cm/H2O
4. Is Ventilation adequate based on Rapid Shallow Breathing Index (RSBI)
  1. RSBI calculated on CPAP 5 cmH2O and NO pressure support for 3 minutes
  2. RSBI = RR/Vt
    1. Where RR = Respiratory Rate
    2. Where Vt = Tidal Volume (in Liters)
  3. RSBI Interpretation
    1. RSBI <105 suggests adequate ventilation
Technique: Spontaneous Breathing Trial (SBT)
1. Perform for 30-60 minutes (with ABG obtained at the end of trial)
  1. T Piece
  2. Pressure Support of 6-8 cmH2O
  3. PEEP 5 cmH2O
2. Assessment: Reassuring findings on SBT
  1. PaO2 >60 mmHg (or O2Sat>90% on FIO2 <0.4)
  2. PaCO2 <50 mmHg (and increased PaCO2 <10 mmHg during SBT)
  3. pH decreases <0.10 during SBT
  4. Respiratory Rate <35
  5. Heart Rate <120-140 (or increases <20% above baseline Heart Rate during SBT)
  6. Systolic Blood Pressure 90-180 mmHg (and >20% change from baseline during SBT)
  7. No significant increased work of breathing during SBT
    1. No accessory Muscle use, paradoxical breathing or diaphoresis
    2. No increased Agitation during SBT
  8. Tidal Volume (Vt) >335 ml (or >4 ml/kg Predicted Body Weight)
Failed Spontaneous Breathing Trial approach (15% of cases)
1. Attempt to wean to pressure support
2. Target comfortable Ventilatory support that does not generate respiratory Fatigue
  1. Gradually wean Ventilator rate by 2 bpm
  2. Gradually wean pressure support to 6-8 cmH2O
3. Continue daily Spontaneous Breathing Trials
4. Consider weaning to BiPAP in COPD exacerbations
Precautions
1. Reintubation is required in 15% of patients even after successful SBT prior to Extubation
References
1. (2025) Introduction of Mechanical Ventilation, Hospital Procedures Course
2. McConville (2012) N Engl J Med 367(23):2233-9 +PMID: 23215559 [PubMed]

Management
Concept of Respiratory Muscle training

Methods
1. Pressure Support (favored by some pulmonologists)
2. T-Tube trials
3. CPAP
4. SIMV is no longer recommended for weaning
Principles
1. Give respiratory Muscles a nightly rest
  1. "Marathon runners do not train around the clock"
  2. Full Ventilatory support at night
  3. Maximize sleep at night
    1. Give Sedative at bedtime (e.g. Ativan, Ambien)
    2. Sleep orders: do not disturb, lights out
2. Use Daily standard screening assessment tool
  1. Completed by Respiratory Therapist
  2. Reduces intubation time (4.5 versus 6 days)
  3. Fewer complications (20% versus 41%)
  4. Ely (1996) N Engl J Med 335:1864-9 [PubMed]

Management
Extubation

Extubation Criteria
1. Are weaning parameters in an acceptable range?
  1. Respiratory Rate <25 breaths per minute
  2. Blood Pressure
  3. Pulse
  4. FIO2 <0.4 to 0.5
  5. PEEP <10 cmH2O
  6. Ventilator Parameters
    1. Minute Ventilation <10 L/min
    2. Tidal Volume > 5 ml/kg
    3. Vital Capacity >10 ml/kg
2. Are secretions controlled?
3. Can the patient protect their airway?
4. Is cough reflex adequate?
5. Is the patient alert?
Extubation Technique
1. Patient is placed in reverse Trendelenburg
  1. Head up
  2. Legs up
2. Monitoring prior to Extubation
  1. Vital Signs
  2. Arterial Blood Gas
Consider Prophylactic Corticosteroids for prevention of Post-Extubation Laryngeal Edema (PLE)
1. Indications: High Risk for Post-Extubation Laryngeal Edema (PLE)
  1. Female Gender
  2. Prolonged Mechanical Ventilation
  3. Endotracheal Tube (ETT) size >8.0
  4. High ETT cuff pressure >25 cmH2O
  5. Failed cuff leak test (cuff leak volume <110 ml or <20% of Tidal Volume)
2. Prophylaxis: Dexamethasone Protocol for prophylaxis
  1. Dexamethasone 0.1 mg/kg (up to 10 mg maximum) IV every 6 hours for 4 doses
  2. Start at least 4 hours before Extubation
3. Management or Post-Extubation Laryngeal Edema (e.g. post-intubation Stridor)
  1. Nebulized Epinephrine immediately (may repeat every 2 hours)
  2. Nebulized Budesonide
  3. Start Dexamethasone protocol if not already initiated
4. PLE Prophylaxis Efficacy
  1. Prophylaxis decreases Post-Extubation Laryngeal Edema (PLE) and reintubation by 50-60%
5. References
  1. Pluijms (2015) Crit Care 19(1):295 +PMID: 26395175 [PubMed]
Post Extubation support
1. Consider High Flow Nasal Cannula (or BiPAP) started immediately after Extubation
  1. Patients transitioned off Ventilator to High Flow Nasal Cannula have lower rates of reintubation
  2. Start at highest tolerable flow rates 50-60 L/min for the first day post-Extubation
2. Pressure Support from 0800 - 2230
  1. PEEP: 5,
  2. Pressure support: begin at 15 and wean
  3. Weaning parameters
    1. Respiratory Rate <30
    2. Tidal Volume > 250 cc
    3. Patient comfortable
    4. Arterial Blood Gas when Pressure Support 3 for 1h
3. AC from 2230-0800
  1. PEEP: 5
  2. AC: 12
  3. Maximize sleep and respiratory rest as above
4. Intermittent Rest throughout the day as needed
  1. PEEP: 5
  2. AC: 12

Reference

(2025) Introduction of Mechanical Ventilation, Hospital Procedures Course
Davies (1986) Acute Respiratory Failure, Cyberlog
Mickman (1995) Lecture, Fairview-Riverside, Minneapolis