Nitrous Oxide (N2O) can be a valuable addition to the dental office analgesia armamentarium. Having a patient that is relaxed can lead to more successful outcomes. 

N2O is delivered to the patient via a nosepiece or hood. Various equipment manufacturers have their own designs of hoods that are designed to be used either with or without a scavenger system. 

A scavenger system is designed to evacuate exhaled gases to minimize contamination of the ambient air within the operatory. The scavenger is connected to your vacuum system (via the HVE) to pull the gas away and vent it to the outside atmosphere (along with your main central vacuum vent). 

To prevent the vacuum from pulling all of the gas before the patient can aspirate (and receive the benefits), all scavenging systems have a vacuum valve and gauge incorporated into the system. This valve controls the level of vacuum so the excess gas can be safely evacuated while the patient still receives an appropriate dose of N2O. 

The gauge pictured below is typical of such devices. It has inlet and outlet connectors for the vacuum line, a control valve to adjust the flow, and a gauge to indicate the current flow setting. Note the green “safe” area indicated on the face of the gauge. Most systems incorporate clear labeling like this to make it easy to set the gauge correctly. 

As the scavenger connects to a HVE valve, there is typically a 7/16” o.d. fitting at the end of the scavenger circuit. All HVE’s sold in the US are designed to take a standard 7/16” tip. This is also the size of the various aspirator tips on the market. These are standardized sizes. 

The hood, however, will vary considerably from manufacturer to manufacturer. Most hoods will have two “inlet” connections for gas to flow to the patient’s nose from the flowmeter. If using a scavenger, there will also be one or more “outlet” hoses pulling the excess (and exhaled) gas away from the patient (and operatory). As an additional means of limiting flow (in addition to the vacuum valve and gauge already discussed) these “outlet” hoses are typically smaller in diameter than the “inlet” hoses. As these hoses fit over connectors, they are measured by inside diameter (i.d.). Whenever you need to replace one of these hoses, always measure the inside diameter to be sure of the proper size. Unlike HVE tips, there can be some variance here so it’s important to know what you have. 

The Accutron scavenger circuit and hood has four connections. This system is also used on Belmed nitrous units. It uses two inlet hoses of 3/8” i.d. (these hoses connect to the side of the hood) and two outlet hoses of ¼” i.d. (these hoses connect to the scavenger “hub” that snaps onto the front of the hood). 

The use of nitrous oxide in your practice can be an important tool in offering your patients a relaxing experience, enhancing recall rates, and resulting in more successful procedures. The scavenging circuit plays an important role in your anesthetic system, allowing you to safely deliver a controlled flow of nitrous oxide and oxygen to your patient, while keeping staff protected. 

Nitrous systems are not a necessary component of your dental practice, but they can be beneficial. The use of nitrous oxide in your practice can be an important tool in offering your patients a relaxing experience. A relaxed patient will result in more successful procedures enhancing recall rates. The scavenging circuit plays a crucial role in the use of nitrous oxide, allowing you to safely deliver a controlled flow of nitrous oxide and oxygen to your patient while keeping staff protected.