What is Anaesthetic Gas?
Anaesthetic gas is a gas that is used to induce anesthesia, which is a state of unconsciousness or partial loss of feeling. Anaesthetic gases are typically inhaled through a mask or breathing tube. They work by depressing the central nervous system, which slows down the heart rate, breathing, and brain activity.
The most common anaesthetic gases are nitrous oxide, halothane, isoflurane, sevoflurane, and desflurane. Nitrous oxide is the simplest and least expensive anaesthetic gas, and it is often used in combination with other gases. Halothane was the first widely used volatile anaesthetic gas, but it has been largely replaced by newer agents due to its potential to cause liver damage. Isoflurane, sevoflurane, and desflurane are all newer volatile anaesthetic gases that are more potent and have a faster onset and offset of action than halothane.
Other anaesthetic gases that are sometimes used include methoxyflurane, enflurane, and xenon. Methoxyflurane is no longer used in the United States due to its potential to cause kidney damage. Enflurane is similar to isoflurane, but it has a longer onset and offset of action. Xenon is a noble gas that is very expensive, but it is also very safe and has a very fast onset and offset of action.
Anesthetic gases are generally safe when used properly, but they can have some side effects, such as nausea, vomiting, and headache. In rare cases, they can also cause more serious side effects, such as malignant hyperthermia, which is a life-threatening condition.
Here is a table of some of the most common anaesthetic gases:
| Gas | Chemical Formula | Onset | Offset |
|---|---|---|---|
| Nitrous oxide | N2O | Rapid | Very rapid |
| Halothane | CH3BrClF | Slow | Slow |
| Isoflurane | CH3CF3CHF2 | Rapid | Moderate |
| Sevoflurane | CH3CHF2OCH2F | Very rapid | Moderate |
| Desflurane | CH2FCF3 | Very rapid | Very rapid |
Anaesthetic Gas CO2 Impact
Anaesthetic gases are greenhouse gases, and their impact is measured by their Global Warming Potential (GWP). GWP is a measure of how effective each gas is at trapping heat in the atmosphere over time compared with carbon dioxide (CO2).
The GWPs of some common anaesthetic gases are as follows:
- Nitrous oxide: 310
- Halothane: 1,140
- Isoflurane: 1,720
- Sevoflurane: 1,300
- Desflurane: 2,540
This means that nitrous oxide is 310 times more effective at trapping heat than CO2, while desflurane is 2,540 times more effective.
The amount of CO2 emitted by anaesthetic gases depends on the type of gas used, the duration of the surgery, and the ventilation system used in the operating theatre. However, it is estimated that anaesthetic gases account for about 5% of the carbon footprint of hospitals.
There are a number of ways to reduce the CO2 emissions from anaesthetic gases. These include:
- Using less potent gases, such as nitrous oxide.
- Using closed-circuit anaesthetic machines, which recycle the gases.
- Using scavenging systems to collect and remove the gases from the operating theatre.
By taking these steps, hospitals can reduce their carbon footprint and help to mitigate the effects of climate change.
Here are some additional information about the CO2 emissions from anaesthetic gases:
- The CO2 emissions from anaesthetic gases are equivalent to the emissions from driving a car for a certain distance. For example, one hour of desflurane use is equivalent to driving 320 kilometers.
- The CO2 emissions from anaesthetic gases are increasing. This is because more and more surgeries are being performed, and the use of potent gases is increasing.
- There is a growing awareness of the environmental impact of anaesthetic gases. This is leading to the development of new, more environmentally friendly gases.