Anesthesia Machine

Everything there is to know about anesthesia machine 

The anesthesia machine is a medical device used to mix the medical gases at constant proportion and generate gas flow. Patients lose temporary sensations during their use and get in the state of unconsciousness, analgesia (relief from pain), paralysis (relaxation of muscles), and amnesia (loss of memory). A patient under the influence of anesthetic drugs, i.e., a mixture of nitrous oxide, Oxygen, and ether vapors, is known as anesthetized. The primary function is to provide proper Oxygen to the patient with anesthetic drugs, remove carbon dioxide from the breathing system in a circulatory way, and provide controlled ventilation. The earliest Boyle's machine had five essential features, which are still present in the modern one. However, there have been many modifications to the current anesthesia machines. These features are a mixture of gasses, pressure gauges on oxygen cylinders, Flowmeter, Vaporizer, and circulatory breathing system.

History of the anesthesia machine

This medical device itself has evolved from a simple pneumatic device to a complex array of mechanical, electrical, and computer-controlled components, which is the basic need of the modern era. Much of the driving force for these changes has been to improve patient safety and user convenience. Hence, in 1846, the Ether anesthesia by WTG Morton was introduced to the public. After this invention, there was no need for change for a long time.

James Gwathmey and William Woosley were US anesthetists who invented an early continuous flow of nitrous oxide, O2, and Ether by this medical device in 1912. These gases passed through two perforated tubes in a glass mixing chamber that contained water. The rate of flow of these gases can be estimated by analyzing the force occurring in the form of bubbles. The same principle is useful in modern devices.

Later, Geoffrey Marshal developed a device during the first world war (1914-1918) based on the Gwathmey machine and presented it before the medical community in 1919. 

In 1917, great scientist Henry Edmund Gaskin Boyle modified the American Gwathmey apparatus of 1912. Ether, which is delivered to the patient at a safe pressure and flow, became the best known continuous flow. He presented it at the royal society of Medicine in London in 1918. As Marshal and Boyle's principle bases on the Gwathmey machine principle, all credit goes to James Taylor Gwathmey.

Boyle's device needed further modifications with time. In 1921, there was the introduction of water to and for the absorption apparatus. In 1927, Flowmeter for carbon dioxide appeared. In 1930, the plunger of a vaporizer and circular absorption system for gases during breathing appeared. In 1933, Dry bobbin flow meter for the gases was introduced. In 1952, the Pin index safety system by Woodbridge connected a high-pressure cylinder containing gasses to a regulator to prevent mistaken use of wrong gases. In 1958, they introduced the Bodok seal, a washer that involves gas-tight between gas supply and gas cylinder.

Basic Principle

The basic principles and specifications remain the same.

  1. The mixture of gasses, i.e., nitrous oxide, Oxygen, and Ether, should be at higher pressure provided to the patient, and the pressure works on this basic principle, F=P×A. If the force is kept constant, then decreeing the regulator's area using a diaphragm, the pressure will increase.
  2. Pressure gauges on the oxygen cylinder are also provided with pressure-reducing valves to supply a limited quantity. 
  3. Flowmeter is used to assess the flow rate of gases that passes through it. 
  4. A metal and glass vaporizer bottle for Ether is useful.
  5. A circulatory breathing system is useful for the exhalation of carbon dioxide and the inhalation of O2.

Indications to use an anesthesia machine

Anesthesia machines are useful in General anesthesia. The Anesthesiologist can utilize it if:

  •  The patient procedure takes many hours.
  •  The procedure affects breathing.
  • The procedure involves the loss of blood.
  • The surgery is of a large body part.
  • The procedure involves body organs like lungs, heart, or brain.

Complications of using an anesthesia machine

This machine triggers several problems, including the delivery of lower oxygen concentration, the supply of high or low volatile liquid concentration to produce vapors, less ventilation, an increase in airway pressures, and misfiling cylinders. It occurs due to the improper adjustment of walls that control the O2 flow. 

Leakage is also a common problem with it. It happens around the tube's connections, valves, and oxygen yokes. 

Another problem is the rise in pressures due to obstruction. Obstructions in pipelines and circuitry to the flow of gas can be due to blood, foreign bodies, secretions. 

As a result of the excessive usage of the anesthesia machine, the patient is marked by hypotension or circulatory failure. In this case, death may result if the patient can't recover quickly, and the patient may have a respiratory or breathing problem and obstructive sleep apnea, which causes them to stop breathing while they sleep. It can be more dangerous for older people because the aging brain does not recover after using an anesthesia machine quickly. 

Hypoxic gas delivery and Hypercarbia is due to problems in the device. In hypercarbia, the retention of carbon dioxide takes place.

The following are some other disadvantages to it:

  • After surgery, a patient may feel sick in the stomach.
  • His or her temperature may rise, and death can also occur.

General specifications 

There are several designs on the market, with different specifications; however, we are going to cite the general specifications, which should be accurate enough.

  • Power Supply: Power input to be 220-240VAC 
  • Oxygen Flush: 35-75 L/min
  • Oxygen supply: At 2000psi 
  • After entering, it is regulated at 45psi 
  • Drawers: 2 in numbers
  • Dual Cascade type flowmeters tube oxygen & N2O range 20ml/min to 10 lit/min.
  • Single tube for air 100 ml to 14 L/min.
  • Vaporize Extended delivery range: 0 to 6 Vol%.
  • Pressure relief valve: 5 to 75 bar
  • Compact Breathing System Volume capacity: 1.7 Lit
  • Ventilator screen size: 6."
  • Ventilator Tidal Volume: 20 to 1400 ml

How they Work

When there is a need to deliver gas to the patient from the anesthesia machine, the O2 supply is provided using a central distribution system for pressure tanks. This connects to the oxygen flow meter, which has a needle to control the flow of Oxygen. Rodent anesthesia machines use the Oxygen of around 0.5-2 liters per minute—vaporizer producers vapors using a volatile liquid anesthetic. Then O2 picks up the anesthetic vapors by passing through the vaporizer. A knob is adjusted to control the precise percentage flow of anesthetic gas from the vaporizer. Modern vaporizers fit it automatically. After mixing with vapors, it flows from the breathing circuit.

This circuit delivers Oxygen and anesthetic to the patient, removes the carbon dioxide from the lungs, and gives assisted ventilation. It flows into the lungs by spontaneous ventilation. While opening the chest cavity, the usage of assisted ventilation is necessary. The respirator can be useful in performing assisted ventilation. Rodent anesthesia machine consists of the non-rebreathing system, which uses very high fresh gas flows. It supplies the anesthetic gas and removes the carbon dioxide from the lungs. This setup consists of a hose that removes excessive gas. To reduce room pollution, it has a scavenging system that absorbs and eliminates excessive unaesthetic gases.

Market Leaders

Famous market leaders who supply it of different brands

  1. Avante 
  2. GE
  3. Drager
  4. Mindray


The anesthesia machine is a useful machine to supply the Oxygen gas mixed with other anesthetic gases to the patients. The basic principle has not changed even evolving from oldest to the modern. Its primary objective is to provide the proper ventilation by removing the exhaled gas in a circulatory way. Modern devices have overcome many issues due to the usage of advanced technology. It is useful during surgery, but some complications can occur like long-lasting numbness, loss of the function of body parts, sickness in the stomach after surgery, or a rise in temperature.

Product filters

$  –  $

  • ‎$10
  • ‎$4000