pco ( 1 - vd / vt · pco 2 ( 1 - v d / v t) hypermetabolism dyspnea hypoxemia anxiety bronchospasm...

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