CMV Mode Workshop

Objectives:

Know the difference between controlled ventilation and assist/control

Controlled variables: PC-CMV vs VC-CMV Phase variables: trigger/limit/cycle Know the breath types Know the breath sequence Settings and adjustment Indications, advantages and

disadvantages

Continuous Mandatory Ventilation

All breaths are mandatory and can be volume or pressure targeted

Controlled Ventilation – when mandatory breaths are time triggered

Assist/Control Ventilation – when mandatory breaths are either time triggered or patient triggered

Mandatory Modes of VentilationCMV

Control Trigger Limit Target Cycle

PressureOr

Volume

Time Pressure or Volume

Time or Volume

Time Triggered Time Cycled Ventilation

Controlled Ventilation: Breath Types

All breaths are mandatory breaths Ventilator determines the start time

(time triggered) Ventilator delivers the set control

(volume or pressure target) Te ventilator ends the breath (time- or

volume-cycled)

Controlled Ventilation: Breath Sequence

All breaths are mandatory breaths

Controlled Ventilation: Indications

Appropriate when a patient can make no effort to breathe or when ventilation must be completely controlled Drugs Cerebral malfunctions Spinal cord injury Phrenic nerve injury Motor nerve paralysis

Controlled Ventilation: Indications

In other types of patients, controlled ventilation is difficult to use unless the patient is sedated or paralyzed with medications Seizure activity Tetanic contractions Inverses I:E ratio ventilation Patient is fighting (bucking) the ventilator Crushed chest injury – stabilizes the chest Complete rest for the patient

Controlled Ventilation: Settings

Adequate alarms must be set to safeguard the patient E.g., disconnection

Sensitivity should be set so that when the patient begins to respond, they can receive gas flow from the patient

Do not lock the patient out of the ventilator!

Flow(L/m)

Pressure(cm H2O)

Volume(mL)

Time Triggered, Pressure Limited, Time Cycled Ventilation Time (sec)

Time CyclingSet PC Level

Control Mode (Pressure-Targeted Ventilation)

Flow(L/m)

Pressure(cm H2O)

Volume(mL)

Time Triggered, Flow Limited, Volume Cycled Ventilation Time (sec)

Preset VT

Volume Cycling

Time Cycling

Dependent onCL & Raw

Control Mode(Volume-Targeted Ventilation)

Pressure Or Volume-Targeted Ventilation

ADVANTAGES

Decreases the work of breathing (WOB)

Helps maintain a normal PaCO2

DISADVANTAGES

Not able to assist the ventilator

Hybrid Modes of VentilationA/C

Control Trigger Limit Target Cycle

PressureOr

Volume

Time Or

Patient

Pressure or Volume

Time or Volume

Time or PatientTriggered Time Cycled Ventilation

Assist/Control Ventilation A time or patient triggered CMV mode in which

the operator sets a minimum rate, sensitivity level, type of breath (volume or pressure)

The patient can trigger breaths at a faster rate than the set minimum, but only the set volume or pressure is delivered with each breath

Volume Controlled-CMV

Time or patient triggered, volume targeted, volume cycled ventilation

Graphic (VC-CMV) Time-triggered,

constant flow, volume-targeted ventilation

Volume Controlled-CMV

Time or patient triggered, volume targeted, volume cycled ventilation

Graphic (VC-CMV) Time-triggered,

descending-flow, volume-targeted ventilation

Pressure Controlled-CMV

PC – CMV (AKA – Pressure control ventilation - PCV)

Time or patient triggered, pressure targeted (limited), time cycled ventilation

The operator set the length of inspiration (Ti), the pressure level, and the backup rate of ventilation

VT is based on the compliance and resistance of the patient’s lungs, patient effort, and the set pressure

Pressure Controlled-CMV

Airway pressure is limited, which may help guard against barotrauma or volume-associated lung injury Maximum inspiratory pressure set at 30 – 35 cm H2O Especially helpful in patients with ALI and ARDS

Allows application of extended inspiratory time, which may benefit patients with severe oxygenation problems

Usually reserved for patient who have poor results with a conventional ventilation strategy of volume ventilation

Flow(L/m)

Pressure(cm H2O)

Volume(mL)

Patient Triggered, Flow limited, Volume Cycled Ventilation

Time (sec)

Preset peak Flow

Time Cycling

Assisted Mode(Volume-Targeted Ventilation)

Flow(L/m)

Pressure(cm H2O)

Volume(mL)

Patient Triggered, Pressure Limited, Time Cycled Ventilation

Time (sec)

Time CyclingSet PC Level

Assisted Mode (Pressure-Targeted Ventilation)

Assist/Control Ventilation Indications

Patients requiring full ventilatory support Patients with stable respiratory drive

Advantages Decreases the work of breathing (WOB) Allows patients to regulate respiratory rate Helps maintain a normal PaCO2

Complications Alveolar hyperventilation

Thank You