1. Mechanical ventilation can be associated with significant morbidity and mortality if prolonged. Weaning patients from mechanical ventilation in a timely manner is important. 2. There are seven stages of weaning which include assessing patient readiness, conducting spontaneous breathing trials, and using various ventilator modes like pressure support to gradually reduce support. 3. Spontaneous breathing trials for 30 minutes to 2 hours are generally preferred for weaning but gradual reduction over days may be better in some cases. Daily assessment of readiness and trials are recommended with prompt reintubation if trials fail.

1. Mechanical Ventilation 3
EICU core review 전임의 김태권

2. Mechanical Ventilation
- Weaning -

3.  Proloned MV associated with significant morbidity & mortality
- Ventilator associated pneumonia (VAP)
- Respiratory & general muscle weakness
- Length of stay↑ (ICU & Hospital)
- Long term care facility use↑
Why weaning is important ?

4. Seven stages of weaning

5. Seven stages of weaning

6. Weaning Indication : Preweaning

7. Seven stages of weaning

8.  원인 질환의 급성기에서 호전된 상태인가?
 적절한 기침이 가능한가?
 기관지 분비물이 과다하지는 않은가?
Suspicion : 임상적 평가

9. Lancet 2008; 371: 126–34
Wake Up & Breathe protocol
Spontaneous Awakening Trials (SATs)
+
Spontaneous Breathing Trials (SBTs)
 All sedatives and analgesics used for sedation are interrupted
 Analgesics needed for active pain are continued
 Monitored for up to 4h
[SAT + SBT] [Usual care + SBT]

10. Seven stages of weaning

11. (Vital capacity)
(Minute ventilation)
(Respiratory rate)
(Tidal volume)
(Rapid shallow breathing index)
 RSBI (RR/VT (L)) < 105
(measured without ventilator support)
 얕고 빠른 호흡 일수록 weaning 실패 가능성↑
Weaning Indication : Parameters
 RSBI (RR/VT (L)) = 30/0.2 = 150 > 105
RSBI는 음성예측도가 높음 (105보다 높을 시 실패 확률 높지만, 낮다고 성공 확률이 높은 것은 아님)
CPAP mode
CPAP 5cmH2O or PSV 5~8 cmH2O

12. (Vital capacity)
(Minute ventilation)
(Respiratory rate)
(Tidal volume)
(Rapid shallow breathing index)
Weaning Indication : Parameters
 MIP (Maximal Inspiratory Pressure) ≤ -20 ~ -30 cmH2O
 호흡근의 근력 측정 : 최대한의 Negative Inspiratory Force를 측정함
 호기상태에서 Expiratory hold maneuver로 (-) pressure를 측정

13. 적절한 산소화의 유지
 SaO2 ≥ 90 % (FiO2 ≤ 40 %)
 P/F ratio ≥ 150~ 200
 PEEP ≤ 5 ~ 8 cmH2O
적절한 호흡 능력 (Clinical criteria + Weaning predictor)
 Patient is able to initiate spontaneous breaths
 RR ≤ 35 회/분
 MIP (maximal inspiratory pressure) ≤ -20 ~ -30 cmH2O
: 호흡근의 근력 측정, 호기상태에서 Expiratory hold maneuver로 흡기 노력에 의한 (-)
pressure를 측정
 VT > 4 ~ 6 mL/kg
 VE < 10~15 L/min (정상인 VE 5~ 6 L/min)
 Arterial pH > 7.25 (no significant respiratory acidosis)
 RSBI (RR /VT (L)) < 105 (measured without ventilator support)
: ventilator circuit의 resistance를 cover할 정도의 positive pressure상태에서 spontaneous
breathing으로 측정함. CPAP 5 cmH2O or PSV 3~5 cmH2O 정도를 적용 . RR/Tidal volume
계산
RSBI는 음성예측도가 높음 (105보다 높을시 실패 확률 높지만, 낮다고 성공 확률이 높은 것
은 아님)
Weaning Indication : Readiness to wean
혈역학적 안정성
 HR < 140 회/분
 Cause of respiratory failure has improved
 sBP 90~180 mmHg
 Hemodynamic stable (without myocardial ischemia)
 No or low dose vasopressor medications
(Dopamine ≤ 5 mcg/kg/min, NE ≤ 0.2 mcg/kg/min)
 Core temperature ≤ 38 ~ 38.5 ℃
 Hb ≥ 8 ~ 10mg/dL
적절한 의식상태
 No sedation
 Adequate mentation on sedation
 Awake or alert or easily arousable (ideal for weaning)
 Abnormal mental state (GCS < 8 or inability to
follow simple command) does not appear to be
associated with higher rate of extubation failure
 Stable neurologic patient

14. Seven stages of weaning

15. Weaning Trial : Weaning method
CPAP modePressure Support mode T-Piece trial
Spontaneous Breathing Trial
Gradual reduction weaning method

16. Best ventilator mode to wean on ?
 Evidence would suggest :
PSV ≈ Intermittent T-piece trial > SIMV
 T-piece trial : 30min trial ≈ 2 hour trial
SBT (Spontaneous Breathing Trial)
Weaning method
 SBT or Gradual reduction (= decreasing level of pressure support, 2~ 4 cmH2O per day)
 SBT is generally preferred, but gradual reduction may be better in certain situation
(장기간의 기계 호흡 사용을 사용으로 호흡근 약화가 예상되는 환자는 gradual reduction를 고려할 수 있음)
 SIMV alone not be used for weaning (not recommend for weaning mode)
 적절한 모니터링과 감시로 weaning failure를 일찍 감지하고 full MV support로 복귀시킨다면 complication은 발생하지 않음
 Weaning 실패시 원인을 파악하고 교정해야 함 & Daily assess for readiness to wean + SBT (Once daily, Not multiple times)

17. Daily SBT
1. Spontaneous breathing with T-piece
2. Spontaneous breathing with PS Mode 5 ~ 7 cmH2O (If ET tube size #7, use PS of 8 -10 cmH2O)
3. Spontaneous breathing with Tube compensation Mode
4. Spontaneous breathing with CPAP (PEEP 5 cmH2O)
 Duration : 30min ~ 2hrs
SBT (Spontaneous Breathing Trial)
SBT with T-piece SBT with PS or TC or CPAP

18. SBT with monitoring

19. SBT failure
 RR > 35 회/분 for 5 min
 SaO2 < 90% for 30sec
 HR > 140 회/분 (or change of ±20% of baseline) for 5 min
 sBP > 180 or < 90 mmHg (sBP 30mmHg↑or 20mmHg↓) for 5 min
 Agitation, Anxiety, Diaphoresis
 Chest pain or SOB (shortness of breath)
SBT (Spontaneous Breathing Trial)
 적절한 모니터링과 감시로 weaning failure를 일찍 감지하고 full MV support로 복귀시킨다면 complication은 발생하지 않음
 Weaning 실패시 원인을 파악하고 교정해야 함
 Daily assess for readiness to wean + SBT (Once daily, Not multiple times)
Sudden onset of PVC (> 4~6 회/min)

20. SBT (Spontaneous Breathing Trial)
 적절한 모니터링과 감시로 weaning failure를 일찍 감지하고 종료 후
full MV support (이전 mode)로 복귀시킨다면 complication은 발생하지 않음
 Daily assess for readiness to wean + SBT (Once daily, Not multiple times)
 Weaning 실패시 원인을 파악하고 교정해야 함

21.  Simple wean : 첫 SBT에 성공한 경우 (약 50~66%)
 Difficult to wean : 첫 SBT 실패 + SBT 성공에 최대 3회 or 7일까지의 시간이 소요되는 경우 (약 26~40%)
 Prolonged weaning : 최소 3번 SBT 실패 or SBT 성공에 8일 이상이 소요 (약 6~14%)
Difficult to wean
Difficult to wean의 원인 (기계 호흡을 적용하게 한 원인을 완전히 치료하지 못한 상태 or 추가적인 새로운 문제의 발생)
- Respiratory/Ventilatory causes : Ventilator demand↓, Reistive load↓, Compliance↓, Neuromuscular capacity↓, Ventilatory drive↓,
Auto-PEEP(COPD), Overventilation (COPD),
- Cardiac causes : Weaning induced myocardial ischemia (or HF), Pulmonary edema with HF (or ischemia), Fluid overload in normal heart
- Psychological causes : Depression, Anxiety, Delirium, Pain, Over-sedation
- Ventilator causes : Equipment dead space, ET tube luminal narrowing, Circuit compliance, Exhalation valve dysfx
- Nutritional causes : Underfeeding & protein catabolism → Respiratory m weakness, Overfeeding CO2 → production & Ventilatory load ↑

22. Extubation screening
+
(Cuff leak test)

23. Extubation Screening
 Is patient awake & responsive to verbal command ? (consider sedation interruption, SAT)
 Can patient protect airway ? (Cough reflex intact ? Voluntary cough (strength) adequate to clear secretion ?)
 Suction frequency ? (check documentation in the prior 6~8 hrs, < q2h)
 Quantity & Quality of secretions ? (< 2.5 cc/h)
 Concerns about the patency of upper airway ? Perform standard cuff-leak test
 If NMD, Can patient sustain head life maneuver against resistance ?
 If patient failed repeatedly (to Weaning trial or Extubation screening), consider tracheostomy if intubated > 2 weeks
 Tracheostomy : WOB↓, Patient comfort↑, Need for sedation↓
 Early tracheostomy (<4days) : No proven benefit (mortality, VAP, aspiration pneumonia, duration of MV)
Extubation screening

24. Approach to cuff leak test & laryngeal edema

26. Post-Extubation & NIV
 Weaning Adjuncts : NIV, HFNO → WOB ↓ (support)
 Extubation → COPD, HFNO (Not alternative to re-intubation)
 NIV (Non-invasive ventilation) : Bilevel respiratory support or CPAP
- Mortality↓(esp. COPD), VAP↓, LOS↓(ICU & Hospital), Reintubation↓, Tracheostomy insertion↓
- COPD & Hypercapnic respiratory failure 환자는 SBT failure에도 weaning 후 NIV 적용을 고려해 볼 수 있음
 Patients at increased risk for extubation failure → preemptive NIPPV in the immediate postextubation period
 HFNO (High flow nasal oxygen) : low level continuous positive airway pressure
- Higher P/F ratio, Ventilator free days↑, Re-intubation↓
- No difference in LOS & mortality
- Needs further evaluation