| What does "Ventilator" mean? |
Vent = an opening allowing gas to pass into or out of.
Ventilator = a device that assists the passing of gas into
and out of the lungs |
| What does it do? |
The ventilator forces a mixture of air and oxygen into the
lungs periodically to enable and assist in the vital transfer
of gases into and out of the blood via the lungs when the patient
is unable to breathe correctly on their own. |
| Physiology |
All living cells in the body use oxygen (O2) and
produce carbon dioxide (CO2). Oxygen is delivered
to the cells and carbon dioxide is transferred away from the
cells via the circulating blood. The oxygen consumed by the
cells needs to be replaced and the carbon dioxide needs to be
removed from the blood. This occurs in the lungs: oxygen in
the air inhaled into the lugs is transferred into the blood
and carbon dioxide is transferred from the blood into the lungs
and is expired. Inspired air contains 79% Nitrogen, 20.96% Oxygen, 0.04% Carbon Dioxide. Expired air contains 79% Nitrogen, 17% Oxygen, 4% Carbon Dioxide. |
| How it works |
A ventilator mixes oxygen and air to required levels and then
delivers it to the patient via special tubing called a “breathing
circuit”. The gas from the ventilator is humidified and
heated in the breathing circuit before it goes to the patient.
The ventilator increases the pressure in the breathing circuit
so that the air is pushed into the lungs for inspiration. The
ventilator reduces the pressure so that the air in the lungs
can be expired and the expired air is vented to atmosphere.
Numerous ventilator parameters are adjustable and are determined by the doctor prior to attachment and during operation on the patient, some of these include: Mode of ventilation - CMV (controlled mandatory ventilation), SIMV (synchronised intermittent mandatory ventilation), CPAP (constant positive airway pressure). Tidal Volume – the volume of air inspired with each breath Respiratory rate – how many breaths per minute (BPM) O2 concentration Flow rate Airway pressure Minute volume – the volume inspired and expired in one minute All of the above are monitored and have various alarm adjustable
limits |
| Units of measurement |
Pressure: cmH20, mbar. Volume: millilitres. Oxygen:
%. Flow: litre/min. |
| Typical values |
Adults: tidal volume, 600 - 1200ml, flow 30-50 litre/min,
resp rate 12 BPM |
| Picture of equipment |
|
 Dräger Microvent |
|