What is the medical anesthesia device and how does it work? Exclusive for 2023



The anesthesia devices give breathing gases (oxygen and air) and nitrous (funny gas) in addition to anesthetic gas (halothane - isofluran - sulvofluran ...) to the patient. Air, oxygen and nitrous enter the device from the gas network or from the cylinders at a pressure ranging between (5-2.5) bar, and these pressures appear on the hours of measuring the pressures on the network or cylinders or the device is equipped with them. The throughput units (air - oxygen - nitrous) receive these gases and through this throughput unit the amount of air flow per minute is controlled to be given to the patient. The throughput unit is usually included from (0-10 liters), in advanced devices there is a throughput unit for the parts of the liter for both oxygen, nitrous and possibly air. 

A branch from the entrance of the oxygen line in order to give 100% oxygen to the patient in resuscitation cases. These gases come out of the throughput unit to the evaporator responsible for giving a specific and controlled percentage of anesthesia gas and this percentage ranges between (0.2-5) % of the value of the gases given to the patient, and from the evaporator the gases go to safety units such as second pressure reducers for safety to ensure that high pressure does not enter the patient's chest in the event of any error in the network pressure reducers or cylinders or in the throughput unit or any error from the medical staff The anesthesia device must be equipped with safety factors to use only one evaporator if there is more than one evaporator installed on the device. A safety system must also be in place to prevent the passage of nitrous.

Testingt :

It is to put the patient in a state of loss of consciousness during the operation to enable the surgeon and staff to perform the operation without the patient feeling pain. It is considered an adjunct to treatment, not a cure. There are two types of anesthesia: the first: local anesthesia and the second: general anesthesia Some anesthetics: Oxygen : 

symbolized by O2 Its presence is necessary because it is a key factor to keep the patient alive Nowruz oxide : N2Ois symbolized by a gas used for loss of consciousness and anesthesia when mixed with oxygen, as this mixture leads to pain relief. Ether: It is in a liquid state and needs to be converted to a gaseous state to enable the patient to inhale the goddess of the idol: it also needs to be converted to a gaseous state through the device.

Anesthesia device: 

  1. Power key.
  2. Evaporator.
  3. Bellows.
  4. Monitor screen.
  5.  Control the patient's oxygen processing.
  6. The key to oxygen saturation in the event of a decrease in the percentage of oxygen sick.
  7. A switch to withdraw fluid through a tube placed in the patient's mouth.Air entry and exit indicators inside the device.

Figure 1)Components of the anesthesia device The most important patterns used in breathing:  

  • Volume controlled ventilation ( vcv ) :

The process of sending a certain fixed volume of air (tidal volume) and specified in a certain amount by the doctor, so the volume is constant with the change of pressure inside the lung, in addition to the needto determine the number of respiratory cycles during one minute, as the patient depends entirely on the device during the surgery.

  • pressure controlled ventilation ( pcv ): 

The process of sending a certain pressure of air (inspired pressure ) and specified in a certain amount by the doctor, so the pressure is constant and the volume is variable, in addition to the need to determine the rate, as the patient depends entirely on the device because he is under the influence of anesthesia. 

  • Synchronized intermittent mandatory ( simv ): 

This method depends on the compatibility between the patient and the device, where it is necessary to determine the tidal volume, but in this method, where the device gives the patient an opportunity to breathe automatically, and in the event of its failure, the device completes the respiratory process.

  • cpap: 

This method depends on supplying the patient with air under a certain pressure while allowing air to enter the air connections, which helps to exchange gases and increase lung efficiency and is used before disconnecting the patient from the device.

  • Pressure support ventilation ( psv ):

It is used for patients who have the ability to breathe but not in sufficient quantity and this method is used to help the patient complete the breathing process.

Patient breathing circuits: 

❖Patient Circuit :

These circuits are divided into four types:

  1.  Open circuit.
  2. Half-open circuit.
  3.  Closed circuit. 
  4. Semi-closedcircuit.

❖Open Circuit :

It is the method of the metal mask, where a metal mask is used, and it is required in this method that the exhaled air is thrown into the air without the patient inhaling at all, the method is old, where the anesthesiologist drips the narcotic substance in the form of drops over a napkin placed near the nose and mouth of the patient, and the drip rate increases by increasing the concentration of narcotic substances, then we replace the napkin with an open mask placed over the patient's nose

and mouth area and a number of layers of gauze to drip over it that method by drip exposed. This method is called open drip.

❖The circuit is half open: 

The most important circuits used in it: 

  • magill:

  1. It is used in anesthesia for children from 5-21 years and for adults as well.
  2. The gaseous mixing between inhalation and exhalation gases is large.
  3. Ghazi Ali Stream.
  4. Mixing gases by excess gas valve.
Its working principle:

The gaseous mixture enters the Inlet and passes through a tube of the inlet to the mask placed on the patient's face, the patient inhales the anesthetic gases and then exhales them as the pressure within the circuit rises, which leads to the opening of the overflow gas valve and the exit of exhaled gases.

  •  Yesterday T l circuit:


  1. This method is considered one of the good ways to anesthetize children up to three years due to the small position in the valve.
  2. The overflow gas valve is canceled.
  3. Ghazi Ali Stream.
  4. There is no opening of any valve to release gases.
  5. The gaseous mixing between inhalation and exhalation gases is less.

❖Semi-closed circuit:

Shown in Figure 4, this circuit does justice that part of the exhaled air is thrown out by the exhalation valve with a little erection, while the other section passes into the breathing bag where the old gas mixes, so the prerequisite for this method is the presence of absorbents to get rid of the accumulation of CO2 gas , so the soda calc circuit is used in this system.


  1. No thermal loss from the patient.
  2. Lack of significant consumption of N2O + O2 gases.
  3. The presence of a little water vapor to moisten the gaseous mixture.
  4. Contains excess gas valve.

❖Closed circuit : 

It has similar features to the semi-suspended circuit and differs from it in that the circuit is semi-suspended when the overflow gas valve is closed.

Circuit of sodily lime:

Absorber Assembly absorbs the absorber of carbon oxide discharged within the breathing circuit of the anesthesia device.

The soda calc circuit consists of two absorption vessels filled with carbon dioxide absorbent, two single-way valves, two pressure system gauges, a connection with the new gas Fresh, manual or automatic line selection valve The Absorber system also allows three types of breathing for the patient: automatic breathing, manual breathing, Automatic breathing.

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