Mechanical Ventilation in Special Conditions
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Transcript of Mechanical Ventilation in Special Conditions
Mechanical Ventilation in Special Conditions
Mechanical Ventilation: Outline
• Head injury• Chest Trauma• Bronchopleural Fistula
Traumatic Brain Injury
Prevalence of extracerebral organ dysfunction in TBI
Cerebral Compliance Curve
Intracranial volume
Intracranial pressureCPP
CPP= MAP-ICP
Cerebral Compliance Curve
50
Cerebral Blood Flow CPP
PaO2
PaCO2
100 150
Head Injury: MV Monitoring
• Peak alveolar pressure, airway pressure, auto-PEEP
• PaCo2 end tidal PCO2• Intracranial pressure• Jugular venous oxygen saturation• Pulse oximetry• Heart rate and systemic blood pressure
Hyperventilation in Traumatic Brain Injury
1. Causes cerebral vasoconstriction 2. Decreases cerebral blood flow3. Decreases cerebral blood volume4. Increases ICP5. Has been proven to be of benefit in head
injuries
Head Trauma
• Cerebral physiology– ICP– CBF– Cerebral oxygenation : SJO2, PbrO2
• Hyperventilation• Lung protective strategy• PEEP• Extubation
Hyperventilation in TBI
• Chronic hyperventilation (PCO2 < 25) should be avoided
• Prophylactic hyperventilation (PCO2 < 35) in the first 24 h should be avoided
• May be necessary for a brief period with acute neurologic deterioration
Head Trauma• Lung protective strategy
– Hypoventilation PCO2 ICP – No evidence of detrimental effect– Use protective ventilation– Observe ICP and CPP if PCO2▲
• PEEP– ICP – MAP – Depends on compliance
• Extubation– LOC– Cough– Tracheal secretions
+
Head Trauma
• Lung protective strategy– Hypoventilation PCO2 ICP – No evidence of detrimental effect– Use protective ventilation– Observe ICP and CPP if PCO2▲
• PEEP– ICP – MAP – Depends on compliance
+
Head Trauma
• Extubation– LOC– Cough– Tracheal secretions
Hyperventilation & CBF
Head TraumaCBF and ICP with hyperventilation
▼ICP
►CBF◄
Head Trauma
• Extubation– LOC– Cough– Tracheal secretions
Intrathoracic Pressure (-3 cm H2O)
CPP = MAP – ICP
MAP (90)= CO X SVRVenous Return
ICP= 10
ICP =30
Maintain adequate MAP• Adequate CO• Use inotropic Agents• Adequate filling pressures• Avoid hypotensive agents• Treat infection abruptly
Avoid ↑ Intrathoracic Pressure• Suppress Valsalva
maneuvers• Suppress cough• ↓ Mean airway pressure• Minimize use of PEEP• Treat distended abdomen
CSF Drainage• HOB > 30 degree• Head in neutral
position• Vetriculostomy
Decrease Oxygen Demand• Prevent seizure• Sedation• Treat pain• Barbiturate coma• Avoid hyperthermia• ? hypothermia
Decrease Brain Water• Mannitol• Avoid D5%• Diuretics
VasoconstrictionPa co2 25-30
Decompressive Craniotomy
Underlying lungdisease
Titrate FiO2 for SpO2 ≥ 92%
no ↓ rate
yes
↓ VT
yes
ICP <20
no↑ FiO2
70-100
FiO2 >0.6
↑ rate
<20
>20
ICP
More aggressiveMedical therapy
Slowly ↓ rate to initial setting
no
ICP
yes
↑ PEEP
CMV (A/C), PCV or VC, VT 4-8 mL/kg, FiO2 1, rate20/min TI1s, PEEP 5 cm H2O
yesCMV (A/C), PCV or VC, VT 4-8 mL/kg, FiO2 1, rate15/min TI1s, PEEP 5 cm H2O
no
>45↑ rate PCO2
↓ FiO2>100
>20
yes
FiO2 > 0.6
<70
MaintainVentilator
Setting
<20
no
Pplat > 30<35
PaO2
35-45
Chest traumaWho Gets Admitted?
• Sternal fractures mediastinal injury• Any 1th, 2nd, 3rd Rib fractures• > 1 Rib fracture in any region• Pulmonary contusion• Subcutaneous emphysema• Traumatic asphyxia• Flail segment• Arrhythmia or myocardial injury
Flail Chest
Flail chest
Flail Chest
BPF
BPF
BPF
Adverse effects of BPF in the ventilated patient
Incomplete lung
expansionLoss of TV
Inability to remove
CO2Loss of PEEP
Pleural space
infection
Factitious ventilator cycling
Guidelines for ventilator management in the patient with BPF
Reduce MAP & RR• Wean patient completely if possible• Partial ventilatory support
– low-rate SIMV or PSV• Minimize minute ventilation• Use of permissive hypercapnia• Avoid patient positions that increase
the leak • Treat bronchospasm• Consider unconventional measures
– Bronchoscopic techniques– HFV– ILV
Independent lung ventilation
Independent Lung Ventilation