TYPES OF BREATHS/MODES:

2 (TYPES) –

(1)    VOLUME CONTROLLED  (VC) BREATH.

The tidal volume is preset and constant, but the pressure varies. The vent will push set volume of gas into the lungs and will use whatever pressure it takes to deliver it, as long as the pressure required does not exceed the alarm limit.

Advantages: guaranteed volume of breath delivery; Disadvantages: high pressures causing leak around uncuffed trach.

Volume Controlled Modes include: Control Mode [CV], Assist Control Mode [AC], and Synchronized Intermittent Mandatory Ventilation [SIMV].

(2)    PRESSURE CONTROLLED (PC) BREATH

The pressure is preset and constant, but now the volume varies. The vent pushes gas into the lungs until a preset pressure is reached. It then holds and maintains that pressure until the "Inspiratory Time" is reached, then the Pt. passively exhales.

Advantages: compensation for leaks & controlled airway pressures; Disadvantages: variable tidal volume delivery.

Pressure Controlled Modes include: Spontaneous Mode [S], Spontaneous Timed Mode [S/T], Timed Mode [T], Pressure Control Mode [PC], and Pressure Control SIMV Mode [PC-SIMV].

 

RSVP currently only uses Spontaneous Mode [S] & Pressure Control-SIMV Mode [PC-SIMV]…

 

Spontaneous Mode [S] – All breaths are “spontaneous” and completely controlled by Pt. "Inspiratory Positive Airway Pressure" or IPAP can be added to assist. IPAP support gives a preset inspiratory push, to make spontaneous breaths deeper.

Pressure Control-SIMV Mode [PC-SIMV] – Vent controls some of the breaths, guaranteeing a minimum minute volume, but allows Pt. to do some breathing on their own. When Pt. makes an inspiratory effort, the vent notices that some of flow has been drawn out of circuit. The set Flow Trigger sensitivity determines how hard Pt. needs to breathe in for vent to sense an extra breath is needed.

 

TERMS TO KNOW:

Tidal Volume (Vt): Volume of inspired gas in mL per breath.

Exhaled Vt (Vte): Vt delivered is close to what is being exhaled. If Vte is significantly less than Vt, may indicate a leak in the circuit or around the trach.

Breath Rate (Set Rate or Backup Rate): Minimum # of vent-controlled breaths delivered per minute.

Respiratory Rate (RR): Total respiratory rate—both backup and Pt. triggered breaths

Inspiratory Time (measured in seconds): If vent in volume control mode – speed of gas going into Pt. (how fast Vt delivered);
If vent in pressure controlled mode – length of time breath stays in the lungs before exhalation.

Minute Volume (MinVent): Amount of gas moved in & out of lungs (measured in Liters) per minute (Total RR x Vt).

Peak Inspiratory Pressure (PIP): The pressure required to push the breath into the Pt. High airway pressures can damage lungs or may indicate obstruction (see alarms).

Positive End Expiratory Pressure (PEEP): The setting that holds pressure in the lungs after exhalation. This helps keep the lungs open, prevent collapse, and oxygenate the blood. Higher the PEEP, the more pressure/ inflation held in lungs after exhalation.

Leak: Amount of gas flow lost from circuit. Some is allowed.

 

ALARMS:

A disconnect can cause a disconnect alarm, a low pressure alarm, a low tidal volume alarm, a low minute volume alarm, low circuit leak.

All vents must have an alarm that signals if there is too much pressure in the circuit, too little pressure in the circuit, or too little tidal volume or minute volume being delivered to the Pt., so the caregiver knows if there is something blocking or impeding gas flow (high pressure) or if there is a leak or disconnect (low pressure and/or low volume).

 

ALARM TYPE

POSSIBLE CAUSE & SOLUTION

Low Exhaled Tidal Volume [Low Vte] and Low Exhaled Minute Volume

(Alarms when pt. breathes less/ slower) (If in PC Mode and Vt decreases).

Same as Low Pressure Limit alarm.

 

Possible airflow obstruction - SOLUTION: If mucus obstruction – suction;
If bronchospasm - bronchodilator per orders.

Low Inspiratory Pressure

(In PC-SIMV mode, the low pressure limit is set at 5cm H2O below the mandatory breath). Pressure should build as a breath is delivered. If there’s a leak or disconnect and pressure drops below preset alarm limit, the vent will sound the alarm.

Leak around the trach - SOLUTION: Reposition head. May need eval for bigger trach.

Disconnected from the vent - SOLUTION: Find disconnect & reconnect the circuit.

Hole in the circuit or cracked water chamber - SOLUTION: Replace.

Loose connection - SOLUTION: Find and tighten the loose connection. Look at all circuit components (temp probe ports, connection to the water chamber and vent outlet port, flex tube, artificial nose, O2 ring, swivel adapter, flow sensor or exhalation lines).

Alarm limit inadvertently changed - SOLUTION: Verify proper setting and adjust.

 

High Pressure Limit

(In PC-SIMV mode, the high pressure limit is set at 5 cmH20 above pressure setting). Vent will stop delivering breath to prevent further pressure build.

Mucus in the airway (volume breaths only) - SOLUTION: Suction.

Bronchospasm (volume breaths only) - SOLUTION: Breathing Tx /Bronchodilator per orders.

Coughing - SOLUTION: N/A

Alarm limit accidently changed - SOLUTION: Verify setting (not adjustable on Trilogy).

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