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Ventilating Pressure(driving force)
Elastic Pressure(volume) +
Resistive Pressure(flow)
VE = ------------------------------------VCO2
pCO2 ( 1 - VD / VT)
hypermetabolism
dyspneahypoxemia
anxiety
bronchospasmmucous plugging
V/Q maldistribution
METABOLIC
MECHANICAL
PRS = Pao +(-Pmus) = (VT / CR) + (VT/Ti x RR) + PEEPtotal
Spontaneous breathing = (0 - (-10))Combination breathing = (10 - (-10))PAP breathing = (10 - (0))
Pressure-Volume Relationships
EEP
EEP = CPAP or PEEP
Transpulmonary pressure = (Pao - Ppl)
∆P
TV = Volume or Pressure Gradient
∆V
Mechanical Breaths
• Control Breaths
• Volume Control
• Pressure Control
• Pressure Regulated Volume Control
• Support Breaths
• Pressure Support
• Volume Support
Volume Cycle
FlowTarget
Variable Pressure
Variable Volume
Variable Flow
Pressure Target
Time Cycle
PRS = Pao +(-Pmus) = (VT / CR) + (VT/Ti x RR) + PEEPtotal
Volume Cycle
FlowTarget
Variable Pressure
Variable Volume
Variable Flow
Pressure Target
Time Cycle
PRS = Pao +(-Pmus) = (VT / CR) + (VT/Ti x RR) + PEEPtotal
Control Breaths
VC PC HybridVolume Set Variable
Time Set SetFlow Set Variable
Pressure Variable Set
+ Volume Synchrony- Synchrony Volume
HYBRID PRVC
CONTROL BREATH
TARGET PLATEAU PRESSURE
> CONTROL
↓ Insp Press
MEASURED < CONTROL
↑ Insp Press
Ventilator InitiatedPatient Initiated
Constant PressureDecelerating Flow
Pressure change + 3 cm H2O /br
Maximum change < 5 cm H2O PIP
Control Breaths
VC PC HybridVolume Set Variable Target
Time Set Set SetFlow Set Variable Variable
Pressure Variable Set Variable
+ Volume Synchrony- Synchrony Volume
Mechanical Breaths
• Control Breaths
• Volume Control
• Pressure Control
• Pressure Regulated Volume Control
• Support Breaths
• Pressure Support
• Volume Support
Pressure Triggering• Pressure sensitivity set at -2 cm H2O
• First two patient efforts reach pressure sensitivity; ventilator triggers breath delivery
• Third patient effort does not reach sensitivity; ventilator does not recognize effort
-2 cm H2O
Flow Triggering• Ventilator delivers a low level of continuous flow into the
patient circuit (open system)
Delivered flowReturned flow
No patient effort
Flow Triggering• Patient inspiratory effort begins with contraction of the diaphragm
• As the patient begins to inhale, some of the continuous flow is diverted to the patient
Delivered flowLess flow returned
Mechanical Modes
• Controlled Mechanical Ventilation
• Assist Controlled Mechanical Ventilation
• Intermittent Mandatory Ventilation
• Spontaneous Ventilation
TRIGGER + BREATH
Modes of Ventilation
Trigger Breath Use
CMV TimeVolume
Pressure Hybrid
Sedation/Paralysis
AC Time or PatientVolume
Pressure Hybrid
90+% MV
from NPB 840 Reference Manual
CMV
AC
Modes of Ventilation
Trigger Breath Use
CMV TimeVolume
Pressure Hybrid
Sedation/Paralysis
AC Time or PatientVolume
Pressure Hybrid
90+% MV
IMVTime
Volume Pressure Hybrid MV or
WeanPatient Spontaneous
from NPB 840 Reference Manual
Acute Respiratory Failure
I. CMV /AC
II. Tidal Volume 6-8 ml / kg
III. RR to achieve 80% of required VE
Mechanical Ventilation Breath Characteristics
Inspiration Expiration
Trigger = Time // Pressure // Flow
Cycle- Time- Volume/Time- Flow Pattern
Target-Volume-Pressure
Mechanical Ventilation Cycle Length
Inspiration Expiration
Target-Volume-Pressure
+ Elastic recoil pressure - Airways resistance
Cycle Length = 1/f
Acute Respiratory Failure
I. CMV /AC
II. Tidal Volume 6-8 ml / kg
III. RR to achieve 80% of required VE
IV. PIF adjusted to I:E > 1:2
Ventilating Pressure(driving force)
Elastic Pressure(volume) +
Resistive Pressure(flow)
PRS = Pao +(-Pmus) = (VT / CR) + (VT/Ti x RR) + PEEPtotal
VE = ------------------------------------VCO2
pCO2 ( 1 - VD / VT)
hypermetabolism
dyspneahypoxemia
anxiety
bronchospasmmucous plugging
V/Q maldistribution
METABOLIC
MECHANICAL
Acute Respiratory FailureI. CMV /AC
II. Tidal Volume 6-8 ml / kg
III. RR to achieve 80% of required VE
IV. PIF adjusted to I:E > 1:2 and peak airway pressure below 30
V. Fi02 to achieve sat > 92%
VI. PEEP at 5.0 cm H20
