What types of ventilation are available?
The type of ventilation determines how and when a breath is delivered to your child. Two types of ventilation are available:
- pressure ventilation
- volume ventilation.
Your healthcare team will carefully assess which type of ventilation your child needs and may recommend changing it as your child’s condition changes.
Pressure ventilation
With pressure ventilation, the ventilator delivers air with pre-set pressures with every breath your child takes. The volume of air delivered to your child may vary from breath to breath. Pressure ventilation is the most common type of ventilation for children.
Volume ventilation
With volume ventilation, the ventilator delivers a pre-set volume of air to the lungs with each breath. The pressures delivered to the lungs may vary from breath to breath.
What types of breath are delivered by the ventilator?
The types of breath delivered by the ventilator depend on how much control your child has over their breathing. There are three main types of breath:
- spontaneous
- mandatory
- assisted.
Spontaneous
A spontaneous breath is one that is started by your child when they breathe in. The amount of air delivered by the ventilator depends on the current pressure or volume setting. Depending on the mode selected on the ventilator, a spontaneous breath ends according to the ventilator settings or when your child breathes out.
Mandatory
A mandatory breath (or mechanical breath) is completely controlled by the ventilator, from the beginning to end. The ventilator controls both the beginning (triggering) and end (cycling) of the breath. The ventilator delivers breaths based on the current pressure or volume setting.
Assisted
An assisted breath is controlled by both your child and the ventilator. Your child starts the breath when they breathe in. The pressure or volume setting controls the delivery of air.
- Volume-assisted breaths will deliver a set tidal volume (volume of air) within a set inspiratory time (time it takes for your child to breathe in).
- Pressure-assisted breaths will deliver the set inspiratory pressure (air pressure when breathing in) for the set inspiratory time.
Breaths end when the set inspiratory time is reached.
What are the modes of ventilation?
Ventilators offer a wide variety of modes that determine how and when a breath is delivered to your child. These modes combine the types of ventilation and types of breaths in different ways, depending on your child’s needs. The mode could change as your child’s condition changes.
Trilogy 200 therapy modes
The Trilogy ventilator offers a wide variety of modes. The most common modes are:
Other common modes include:
- assist/control (A/C)
- continuous positive airway pressure (CPAP)
- spontaneous (S)
- timed (T)
- pressure control (PC)
- control ventilation (CV)
- synchronized intermittent mandatory ventilation (SIMV).
Assist/control (A/C)
In this mode, the ventilator is set up to deliver a certain number of breaths per minute to your child. The child can make an effort to breathe and the ventilator will respond by delivering a mandatory breath. The sensitivity setting needs to be set properly so that the ventilator knows that the child is making an effort to breathe.
Continuous positive airway pressure (CPAP) ventilation
With CPAP, the ventilator will deliver the same pre-set pressure level throughout inspiration and expiration. This helps with oxygenation (see information on PEEP below). Your child starts and sustains their breathing. The ventilator delivers no mandatory breaths.
The ventilator can be set so that your child receives additional pressure support, which helps decrease the work needed to breathe.
Spontaneous (S)
In spontaneous mode, the ventilator provides a constant pressure of air once it senses that your child has made an effort to breathe. This helps your child take a bigger breath and decreases the work needed to breathe. Your child controls the size of each breath and how many breaths they would like to take in one minute.
Timed (T)
In timed mode, the ventilator provides a set number of mandatory breaths, regardless of patient effort, based on the ventilator rate that is set. The length of the mandatory breath depends on the inspiratory time setting on the mechanical ventilator.
Spontaneous/timed (S/T)
The ventilator delivers both spontaneous and mandatory breaths. A mandatory breath is delivered if your child does not spontaneously breathe within a set period of time. This makes sure that your child receives a minimum number of breaths per minute.
- The length of the spontaneous breath depends on your child’s effort.
- The length of the mandatory breath depends on the inspiratory time setting on the mechanical ventilator.
Pressure control (PCV or PC)
In this mode, the ventilator delivers air to your child until the air reaches the set pressure level. The breath is held at that pressure for the set inspiratory time (breathing-in time) before the child can then breathe out on their own.
Control ventilation (CV)
With control ventilation, your child receives a mandatory breath with a pre-set tidal volume. The length of time that the breath should be delivered is also set carefully. In this mode, the ventilator does not respond to your child’s efforts. PEEP is delivered when your child breathes out.
PEEP is positive end expiratory pressure. Most ventilators provide this extra pressure to hold the lungs open so the air sacs do not collapse. Children who have tracheostomies, and are ventilated, need PEEP to be set on the ventilator to make sure their lungs receive enough oxygen.
Synchronized intermittent mandatory ventilation (SIMV)
SIMV allows the ventilator to deliver a set number of mandatory breaths per minute. Between these mandatory breaths, your child can breathe on their own, controlling the size and number of spontaneous breaths.
This mode of ventilation is synchronized because the ventilator senses when your child is making an effort to breathe. If it is close to the time to deliver a mandatory breath, the ventilator will adjust the timing so that the breath is delivered when the child is trying to breathe in. This helps to keep the child comfortable on the ventilator.
SIMV can be combined with pressure support ventilation (PSV). In that case, the ventilator delivers a set number of mandatory breaths per minute. Between those mandatory breaths, your child can take spontaneous breaths and the ventilator will provide pressure support.
SIMV can also be combined with pressure control ventilation (PCV). In that case, the mode is called PC-SIMV and the ventilator delivers a variety of breaths (spontaneous, mandatory and assisted) depending on your child’s breathing pattern.
Pressure support ventilation (PSV or PS)
PS is a feature that can be added to PC mode or SIMV mode. The ventilator provides a constant pressure of air once it senses that your child has made an effort to breathe. This helps your child take a bigger breath and reduces the work needed to breathe. Your child controls the size of each breath and how many breaths they would like to take in one minute.