II. Pathophysiology
- Ventilated for less than 2 weeks
- Respiratory Muscles do not decondition significantly
- Exceptions
- Comorbid condition or
- Severe increased VO2 with negative nitrogen balance
- Majority of patients do not need Ventilator Weaning
- Either need the Ventilator or they do not
III. Indications: Weaning
- Prolonged debilitated state, deconditioning or weakness
- Chronic Obstructive Pulmonary Disease
- Severe Congestive Heart Failure
- Catabolic State
- Results from high dose Corticosteroids
- Results in weak chest Muscles
IV. 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
- Place Dobbhoff NG tube (check placement with XRay)
- Select a supplement (e.g. FS Pulmocare)
- Measure q4 hour Residual Volumes
- Consider prokinetic agent for >50 cc residuals
- Metoclopramide (Reglan) 10 mg PO qid
- Erythromycin 250 to 500 mg PO qid
- Consider prokinetic agent for >50 cc residuals
V. Management: Preparation for weaning - Pulmonary Status
- Maximize bronchodilation if bronchospasm
- Consider Inhaled Corticosteroids over systemic
- Avoid Respiratory Acidosis
- Adjust pCO2 to premorbid level
VI. Management: Preparation for weaning - Psychosocial Status
- Alleviate anxiety
- Reassure of support
- Encourage optimism. and discourage discouragement
- Try not to convey frustration
VII. Management: Preparation for weaning - Cardiac Status
-
Coronary Artery Disease
- Consider Anti-Anginal medications (Nitroglycerin)
- Check Electrocardiogram
- Baseline
- After a failed weaning trial
-
Congestive Heart Failure
- Maximize volume status
- Reduce Afterload
- Use inotropic agents as needed (Dopamine, Dobutamine)
VIII. Management: Preparation for Weaning - Sedation
- Hold benodiazepines (use only prn)
- Decrease Propofol and Fentanyl rates every 4 hours
- Consider Dexmedetomidine (Precedex)
IX. Management: Concept of Respiratory Muscle training
- Methods
- IMV
- Pressure Support (favored by some pulmonologists)
- T-Tube trials
- CPAP
- Principles
- Give respiratory Muscles a nightly rest
- "Marathon runners do not train around the clock"
- Full Ventilatory support at night
- Maximize sleep at night
- Use Daily standard screening assessment tool
- Completed by Respiratory Therapist
- Reduces intubation time (4.5 versus 6 days)
- Fewer complications (20% versus 41%)
- Ely (1996) N Engl J Med 335:1864-9 [PubMed]
- Give respiratory Muscles a nightly rest
X. Management: Extubation
- Extubation Criteria
- Are weaning parameters in an acceptable range?
- Respiratory Rate <25 breaths per minute
- Blood Pressure
- Pulse
- FIO2 <0.4 to 0.5
- PEEP <10 cmH2O
- Ventilator Parameters
- Minute Ventilation <10 L/min
- Tidal Volume > 5 ml/kg
- Vital Capacity >10 ml/kg
- Are secretions controlled?
- Can the patient protect their airway?
- Is cough reflex adequate?
- Is the patient alert?
- Are weaning parameters in an acceptable range?
- Extubation Technique
- Patient is placed in reverse Trendelenburg
- Head up
- Legs up
- Monitoring prior to Extubation
- Patient is placed in reverse Trendelenburg
- Post Extubation support
- Consider High Flow Nasal Cannula started immediately after Extubation
- Patients transitioned off Ventilator to High Flow Nasal Cannula have lower rates of reintubation
- Start at highest tolerable flow rates 50-60 L/min for the first day post-Extubation
- Pressure Support from 0800 - 2230
- PEEP: 5,
- Pressure support: begin at 15 and wean
- Weaning parameters
- Respiratory Rate <30
- Tidal Volume > 250 cc
- Patient comfortable
- Arterial Blood Gas when Pressure Support 3 for 1h
- AC from 2230-0800
- PEEP: 5
- AC: 12
- Maximize sleep and respiratory rest as above
- Intermittent Rest throughout the day as needed
- PEEP: 5
- AC: 12
- Consider High Flow Nasal Cannula started immediately after Extubation
XI. Reference
- Davies (1986) Acute Respiratory Failure, Cyberlog
- Mickman (1995) Lecture, Fairview-Riverside, Minneapolis