Ventilator Modes and Troubleshooting

Complete mechanical ventilation (CMV)

Mode of ventilation where patient does 0 work, machine does 100% of the work of breathing

Requires heavy sedation and sometimes paralysis

Machine controls every single aspect of patient's breathing

When is complete mechanical ventilation usually used?

Rarely used today except for when patient has no spontaneous drive to breathe

High C-spine fracture

Certain neuromuscular conditions

Neurological disorders who have high intracranial pressure --> Need tight regulation of CO2 levels to prevent further increases in ICP

Why is heavy sedation and paralysis necessary for patients on complete mechanical ventilation?

Critical that patient is not taking any spontaneous breaths on their own

Ventilator will not sense respiratory effort and will not provide airflow into the lungs during inspiration

Can lead to respiratory distress

Assist control ventilation (A/C)

One of most common modes of ventilation in ICU

Can be done either with volume-cycling or pressure-cycling

Patient does about 20% of the work!

Machine is doing about 80% of the work --> Patient may take their own initiated breaths --> Machine will assist patient by delivering a full breath at the set tidal volume

Assist control ventilation sensitivity setting

Determines how much effort the patient needs to make before the machine senses they are trying to take a breath

Decreasing sensitivity --> Patient will have to do more work before machine senses they are trying to breathe

Increasing sensitivity --> Patient has to do less work before machine senses they are trying to breathe

When is assist control ventilation used?

Often initial mode of breathing when a patient goes on the ventilator

Helpful in many lung conditions like ARDS, severe asthma, COPD

Patients recovering from surgery who cannot breathe on their own in the immediate post-op period

Patients who have respiratory arrest following drug overdose

States of shock

What to look out for with assist control ventilation

Patient's respiratory rate

The machine will respond to those breathes --> If breathing too fast it can cause respiratory alkalosis

Synchronized intermittent mandatory ventilation (SIMV)

Hybrid ventilation mode

Patient does about 60% of the work!

Machine will not assist the patient's spontaneous breathing

Respiratory rate is set with tidal volume for the "mandatory breaths" --> In-between these breaths the patient can breathe on their own, with varying tidal volumes based on patient's work

When is synchronized intermittent mandatory ventilation used?

Excellent mode when the patient is being weaned off the ventilator --> When used as a weaning mode, usually set at about 4-6 breathes per minute

Encourages patient to breathe spontaneously and to work their respiratory muscles

Pressure support ventilation

Patient does 100% of the work of breathing!

Ventilator does provide a slight positive pressure airflow into the patient during spontaneous inspiration, making it easier for them to breath and overcome resistance of ET tube

Used during daily spontaneous breathing trials to determine readiness for extubation

Has an apnea monitor --> If patient stops breathing, machine will kick in and provide full support

Pressure support ventilator precautions

Must monitor patient closely to assure they aren't hyperventilating or hypoventilating

What to do when a ventilated patient becomes acutely hypoxic or is struggling to breathe

DOPE Mneomonic

Displacement

Obstruction

Pneumothorax

Equipment failure

If cannot find any source of why --> Remove from ventilator and bagged with 100% O2 through ambu bag at 1 breath every 6 seconds

Displacement of ET tube

Check ET tube to make sure is has not become dislodged

Make sure at same position of insertion depth

Obstruction to airflow into and out of lungs

Is the pt biting on the ET tube?

Is there a kink in the tubing?

Is there a blocked inflow or outflow area on the tubing?

Is there a mucous plug?

Pneumothorax ventilator

Listen to chest and see if there are bilateral breath sounds

Equipment failure

If there are no waveforms on the ventilator

If the ventilator is flashing 'ventilator failure'

Immediately remove pt from ventilator --> Begin bagging the pt through ETT at a rate of 1 breath every 6 seconds --> Call for help

Ventilator safety precautions

Make sure it is plugged into a red emergency outlet

If ventilator is unplugged, it has a backup battery --> It will function but alarm loudly, plug back in immediately ASAP

High pressure alarms

Set to go off when airway pressure is 10-20 cm H2O above the patient's peak airway pressure

Ventilator is meeting too much opposition when trying to deliver a breath

Major causes is increased airway resistance and decreased airway expansion

Increased airway resistance causes

Occurs when airways becomes narrower

Thick secretions in the airway

Bronchospasm

Bronchoconstriction

Kinking of the ventilator tubing

Displacement of the ET tube

Pt coughing and biting the ET tube

Interventions for high pressure alarm caused by increasing airway resistance

Suctioning the patient

Checking ventilator tubing for kinks

Assessing breath sounds --> If wheezing, then pt may need bronchodilator

If pt is biting tube --> Assess RASS score and determine whether sedation is necessary

Decreased airway expansion causes

Airways become stiffer

Airways become filled with fluid or debris --> Making it harder for alveoli to expand

Pulmonary edema

Pneumonia

Atelectasis

ARDS

Sudden pneumothorax

Interventions for a high pressure alarm caused by decreased airway expansion

Assessing breath sounds

Treating underlying problem

Diuretics for pulmonary edema

Chest tube for pneumothorax

Other interventions for ARDS and pneumonia (may need to be placed on pressure-controlled ventilation while being treated)

Low pressure alarms

Occur when the ventilator detects a low exhaled tidal volume compared to the amount of air being delivered to the patient --> For example, receives 600 mL of tidal volume during inspiration and only 400 mL is returned during exhalation

Can also happen if machine senses very low pressure while delivering a breath

Major causes of low-pressure alarms

Tubing disconnection from ETT or ventilator

Leak around the balloon on the ET tube

A leak in the tubing circuit from the patient to the ventilator

Patient is over breathing the ventilator, causing machine to sense very low airway pressure

Low-pressure alarm interventions

Check all tubing connections from the ETT to the machine and back to ensure no disconnections or leaks

If patient is over breathing and their RASS score is high, may need sedation

Apnea alarm

Occurs when the machine detects that the patient is not breathing (doesn't sound in CMV bc machine does all the work anyway)

Most ventilators will begin to deliver breaths to the patient to prevent respiratory compromise

Apnea alarm common causes

Patient fatigue

Overmedication with sedation

Decreased level of consciousness

Apnea alarm interventions

Assess vital signs for signs of fatigue (high HR, high BP, decreased O2)

Assess RASS score to check for over sedation