1 pre-icu training chest mechanical ventilatory support 2008/6/20
TRANSCRIPT
1
Pre-ICU TrainingCHEST
Mechanical Ventilatory Support
2008/6/20
2
What is Mechanical Ventilator?
• Specially designed pumps that can support the ventilatory function system and improve oxygenation through application of high oxygen content gas and positive pressure.
3
Indications for Mechanical Ventilator
• Hypoxemic respiratory failure: PaO2 < 60mmHg with the FiO2 > 60%
• Hypercapnic respiratory failure: pH < 7.35 with PaCO2 > 50mmHg
• Respiratory rate > 35/min
• Others
4
Types of Mechanical Ventilator
• Positive pressure vs. Negative pressure
• Invasive vs. Non-invasive
5
Definition
• Mode: manner in which ventilator breaths are triggered, cycled, and limited
• Trigger: what the ventilator senses to initiate an assisted breath
• Cycle: factors that determine the end of inspiration
• Limit: operator-specified values
• Flow: Liters/min
6
Positive end-expiratory pressure (PEEP)
• Prevent collapse of alveoli
• Improve oxygenation
• Intrinsic and Extrinsic PEEP
7
8
Ventilator Modes
• Assist control mode ventilation (ACMV)
• Pressure-Control ventilation (PCV)
• Synchronized intermittent mandatory ventilation (SIMV)
• Continuous Positive Airway Pressure (CPAP)
• Pressure-support ventilation (PSV)
9
Mode Independent Variables (Set by User)
Dependent Variables (Monitored by User)
Trigger/Cycle Limit
ACMV
1. FIO2
2. Tidal volume3. Ventilator rate4. Level of PEEP5. Inspiratory flow pattern6. Peak inspiratory flow7. Pressure limit
1. Peak airway pressure, PaO2, PaCO2
2. Mean airway pressure3. I/E ratio
Patient/timer
Pressure limit
ACMV
From Harrison’s principles of internal medicine, table 252-1
10
Advantages Disadvantages Initial Settings
1. Timer backup2. Patient-vent
synchrony3. Patient controls
minute ventilation
1. Not useful for weaning2. Potential for dangerou
s respiratory alkalosis(Tachypnea)
1. FIO2 = 1.02. Vt = 10–15 mL/k
g3. f= 12–15/min4. PEEP = 0–5 cmH
2O5. Inspiratory flow
= 60 L/min
ACMV
From Harrison’s principles of internal medicine, table 252-1
11
ACMV
12
Mode
Independent Variables (Set by User)
Dependent Variables (Monitored by User)
Trigger/Cycle Limit
PCV 1. FIO2
2. Inspiratory pressure level
3. Ventilator rate4. Level of PEEP5. Pressure limit6. I/E ratio
1.Tidal volume2. Flow rate,
pattern3. Minute
ventilation4. PaO2, PaCO2
Timer/patient
Timer/pressure limit
PCV
From Harrison’s principles of internal medicine, table 252-1
13
Advantages Disadvantages Initial Settings
1. System pressures regulated
2. Useful for barotrauma treatment
3. Timer backup
1. Requires heavy sedation
(inverse I/E ratio when severe hypoxemia)
2. Not useful for weaning
FIO2= 1.0PC = 20–40 cmH2OPEEP = 5–10 cmH2Of= 12–15/minI/E = 0.7/1–4/1
PCV
From Harrison’s principles of internal medicine, table 252-1
14
PCV
15
Mode Independent Variables (Set by User)
Dependent Variables (Monitored by User)
Trigger/Cycle Limit
CPAP FIO2
Level of CPAP
Tidal volume
Rate, flow pattern
Airway pressure
PaO2, PaCO2
I/E ratio
No trigger
Pressure limit
CPAP
From Harrison’s principles of internal medicine, table 252-1
16
Advantages Disadvantages
Initial Settings
Allows assessment of spontaneous function
Helps prevent atelectasis
No backup FIO2= 0.5–1.0b
CPAP = 5–15 cmH2O
CPAP
From Harrison’s principles of internal medicine, table 252-1
17
CPAP
18
Mode
Independent Variables (Set by User)
Dependent Variables (Monitored by User)
Trigger/Cycle Limit
PSV FIO2
Inspiratory pressure level
PEEPPressure limit
Same as for PCV + I/E ratio
Inspiratory flowPressure limit
PSV
From Harrison’s principles of internal medicine, table 252-1
19
Advantages Disadvantages Initial Settings
Assures synchrony
Good for weaning
No timer backup FIO2= 0.5–1.0PS = 10–30 cmH2O5 cmH2O usually the level use
dPEEP = 0–5 cmH2O
PSV
From Harrison’s principles of internal medicine, table 252-1
20
PSV
21
Weaning from Mechanical Ventilator
• Discontinuation of mechanical ventilatory support
22
Modes for Weaning
• SIMV
• PSV (8-10cmH2O)
• Spontaneous T-piece trial
23
Factors in the weaning process
• Weaning parameters• Endotracheal tube• Arterial blood gases• Nutrition• Secretions• Neuromuscular factors• Obstruction of airways• Wakefulness
From Washington’s Manual, table 8-3
24
Guidelines for assessing withdrawal of mechanical ventilation
• Patient’s mental status• PaO2 > 60mmHg with an FiO2 < 50%• PEEP < 5cmH2O• PaCO2 and pH acceptable• Spontaneous tidal volume > 5ml/kg• Vital capacity > 10ml/kg• MV < 10L/min
From Washington’s Manual, table 8-4
25
Guidelines for assessing withdrawal of mechanical ventilation
• Pimax < -25cmH2O• Respiratory rate < 30/min• Static compliance > 30ml/ cmH2O
– Tidal Volume/ (plateau pressure – PEEP)– Static compliance reflects elasticity
• Rapid shallow breathing index (RSI) < 105 breaths/min/L– Ratio of Breathing frequency to Tidal volume
• Stable vital signs after one 1- to 2-hr spontaneous breathing trial
26
THE END
Thanks for your attentions!