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Introduction to Dental Nitrous Gas delivery system

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Introduction to Dental Nitrous Gas delivery system

A Nitrous Oxide delivery unit is a medical device for measuring, controlling and delivering medical gases in critical treatment procedures.  Nitrous Gas is widely accepted and a recognized conscious sedation technique to allow medical professionals performing invasive treatment procedures by producing maximum comfort to the patients since 1800s. Also known as “relative analgesia” or “oxygen-nitrous analgesia”, according to ADA survey concluded that over 70% of all dentistry clinics following Nitrous Gas sedation technique.  Considering the fact that Nitrous Gas Delivery System is a class 3 medical device, it is critical to follow a regular maintenance procedure to ensure that safety and efficacy are not compromised.

Generally, Nitrous Delivery devices can be branched into two main families: analog and digital. Following this article, there will be a concentration on analog type as a pioneer in Nitrous Flowmeter industry.

Areas and Conditions of Application of the Nitrous Gas Delivery Systems:
Nitrous conscious sedation method recommended itself as one of the most reliable sedation techniques in dentistry against various conditions. As a result, wide spectrum healthcare industries included the aforementioned regimen into their practice. Indications include but not limited:

Chest pain secondary to angina;
Acute myocardial infarction;
Kidney Stones, urinary retention, burns;
Fractures or traumas.
Anxiety or fear before the treatment procedures;
Various invasive dental procedures.

Following all the indications, there is a number of contraindications:

Altered mental status;
Intoxication or drug use;
Maxillofacial abnormalities;
Respiratory distress;

The principle of action

Nitrous oxide possesses important features like colorless, odorless and nicely-smelling inorganic substance that allowing conscious sedation with minimum side effects. The gas delivery journey starts from inhalation through an upper respiratory tract proceeding to the lungs where absorption takes place. Nitrous oxide main features like low solubility and rapid redistribution allow the sedation agent to enter BBB (Blood-Brain Barrier) and positively affect certain parts of the brain. During the bloodstream circulation, a nitrous agent doesn’t interact with Hb proteins and maintains a non-alteration state. The elimination process follows the same route as absorption; all nitrous oxide particles exhaled through an upper respiratory tract.

The architecture of the General Analog Nitrous Oxide System

Flow meter and Patient Circuit consists of:

Nitrous and oxygen flow meter tubes

  • Mixture dial
  • Flow control knob
  • Oxygen flush button
  • Air inlet valve
  • Pressure regulator and fail-safe
  • Bag mount and breathing bag
  • Breathing tube connector and non-re-breathing check valve
  • Breathing tube
  • Connector, tubing, and inhaler

Flow-meter back view:

  • Nitrous male connector
  • Oxygen male connector
  • Standard pipe plug

 Scavenging assembly:

  • Vacuum Shut-Off valve
  • Fresh gas connector
  • Scavenger

Preventative Maintenance and Troubleshooting protocols from TRH Services.

A TRH Services highly skilled biomedical technologists provide wide spectrum maintenance and testing procedures by using specialized equipment to ensure the device passes all safety standards. The most commonly used diagnostic devices are electrical safety analyzer, oxygen analyzer, and flow meter. TRH Services developed a unique on the market certification reports that provide confident and conclusive inspection results convenient for customers and technologists.

Visual or Physical Inspection

Firstly, the technician examines the device and accessories for signs of wear, damage or other types of defects. Another common issue is observed during a visual inspection is missing parts that could cause unit malfunction. Our team usually document the following concerns: patient circuit or scavenging tubing cracked, breathing bag is worn out, flow-meter tube damaged or even loose connections. All of these and more issues could have a significant impact on the treatment quality and safety of the patient.

Functional Tests

Following the visual inspection, the TRH Services team ensures that the unit receives the gases with no interruption. The technician starts the unit by allowing oxygen to flow under the maximum rate; the same repeated with nitrous. Functionality test most commonly indicates: noisy operation (may be linked to check-valves, o-rings, loose connections, worn out tubing or breathing bag), some knobs or/and buttons are not responsive; sticky oxygen flush button.

Concentration and Flow Rate

Lastly, the gas concentration and flow rate must be evaluated to permit safety usage. The minimum oxygen concentration allowed is 30%, therefore, maximum nitrous is 70%. Oxygen analyzer helps us to determine exact oxygen concentration during three steps of adjustments: 100%, 50%, and 30%. The same pattern is followed by nitrous oxide: 0%, 50%, and 70%. If gas concentration is out of range, it’s indicative of major leakage or calibration related problem. Flow rate measurements are done along with oxygen concentration readings. The goal is to obtain accurate gases flow at 3, 6 and 9 LPM (liters per minute) with minimum tolerance.

Finalizing the inspection, the failsafe feature must pass the testing protocol. A failsafe block is responsible for uninterrupted oxygen delivery even if nitrous is not present. On another hand, it interrupts nitrous delivery if oxygen is not present. Generally speaking, no nitrous without oxygen and oxygen even if there is no nitrous.


The nitrous gas delivery system is a gold standard class 3 device for conscious sedation in the medical field that requires an exceptional approach for maintenance and service. Our team recommends following the Canadian Standards Association (CSA) guideline to minimize risks of harmful gases accumulation and staff-patient injury.

Please follow this link to see common Nitrous Gas Delivery Systems.

Here is a list of some of the Nitrous Gas delivery systems we can test:

ManufacturerModel Number
Accutron Inc.Ultra PC
Accutron Inc.Digital Ultra
Belmed Inc.5000
Fraser Sweatman Inc.MDM
Fraser Sweatman Inc.N/A
Fraser Sweatman Inc.RA
MDS Matrx94500011
MDS MatrxDigital MDM
MDS MatrxMatrx
MDS MatrxMDM Digital
Modular Driven Technologies Corp. (MDT)70-3500-30
OhmedaFraser MDM
Ormco CorporationN/A
Parker Hannifin Corporation40151617
Parker Hannifin CorporationDigital MDM
Parker Hannifin CorporationDigital-MDM
Porter Instruments Co.02000
Porter Instruments Co.2000
Porter Instruments Co.2045-2
Porter Instruments Co.91500167
Porter Instruments Co.C2000
Porter Instruments Co.C-2000
Porter Instruments Co.C300
Porter Instruments Co.C3000
Porter Instruments Co.MDM
Porter Instruments Co.MXR
Porter Instruments Co.MXR-1
RA Medical Services LtdMDM
RA Medical Services LtdRA

Written By: Jan Kara

Edited By: Tyler Hasenpflug CET