Infection Control Guide to Care of Inhalation Sedation Flowmeters and Scavenger Breathing System Components

Infection Control procedures for use and care of this type of equipment are frequently misunderstood and the intention of this article is to guide and assist with provision of a suitable Infection Control Protocol.

Section 1. Inhalation Sedation Flowmeters

As defined in ‘A Conscious Decision’ published by the Department of Health in 2003 the section for Equipment for Conscious Sedation states:
“Of the various reports since 1967, the Poswillo Report made the most specific recommendation for the equipment and drugs which dental practices should have to support the practice of sedation. This included the availability and use of dedicated inhalational sedation machines capable of delivering a fixed maximum level of nitrous oxide and a fixed minimum level of oxygen when providing relative analgesia (a particular sedation technique using inhalation); the use of indwelling cannullae for intravenous sedation; and additional equipment for the resuscitation of patients who had received sedation. It is essential that all machines used for conscious sedation meet the above guidelines bearing in mind the potential for general anaesthetic machines to be used for conscious sedation. The Group recommends that all inhalation sedation machines should be regularly maintained and equipped to the British or European Standard applicable at the time of their purchase.” (ref 1)

The most commonly found types of Inhalation Sedation Flowmeters are currently:

• Cyprane or Matrx Analogue MDM (also referred to as Quantiflex)
• Quantiflex Mark II
• Matrx Digital MDM
• Porter C2000 & C3000 MXR
• McKesson 882 / 883 & Mc1
• Accutron Ultra & Newport

These are dedicated Inhalation Sedation machines. Units still in production are:

• MDM / DMDM / C3000 MXR – all manufactured by Porter Instruments Inc, USA
• McKesson Mc1 – manufactured by McKesson/Cestradent, UK
• Ultra / Newport – manufactured by Accutron Inc, USA

All of the above units have dedicated one-way valving on the fresh gas outlets. These valves also incorporate bag tees which direct some of the titrated gas flow into a reservoir bag. In units which are correctly maintained, this valving is preserved and effectively means that the inside of the IS unit and bag will never become contaminated by human breath. This protection is usually assisted by the breathing system used to deliver titrated gas mix to the patient. By the same token, use of bacterial filters, as with G A circuits – is not necessary or desirable.

External cleaning of the flowmeter body varies according to Manufacturer/type; The Matrx MDM and DMDM can be wiped over externally by using a germicide containing glutaraldehyde, following the manufacturer’s directions for use. Care must be taken with the touch screen face of the DMDM, alternatively a disposable barrier shield can be used. In the case of the C3000 MXR, the recommendation is to use an approved disinfectant for the dental environment – again, following the disinfectant manufacturer’s directions (and cautions) for use. Similar procedures would be recommended for other types of flowmeter. The DMDM and C3000 MXR are part of the ‘new generation’ of sedation flowmeters designed with infection control in mind.

Please note: Flowmeters must never be immersed in liquid. If this happens, please quarantine and contact the service provider.

Reservoir bags

Reservoir bags are usually composed of a grey non-latex material. These are protected from internal contamination by the non-return valving of the flowmeter outlet. If required, they can be externally cleaned with a mild detergent such as Tri-Sodium Phosphate or a neutral liquid soap. The product can also be autoclaved providing the maximum temperature does not exceed 137 degrees Celsius. Lower sterilisation temperature will extend product life. It is not necessary to change the reservoir bag between patients or use disposable (green).

Section 2. Scavenger Breathing Systems

Cleaning and sterilisation of these will vary considerably with regard to manufacturer instructions. The most frequently seen types on the UK marketplace are:

• Porter brown double mask breathing System
• Matrx ANS (Autoclavable Nitrous Scavenger) System
• Matrx Passive Scavenger System
• Accutron Scavenging System

Porter brown System

This system is composed of mostly autoclavable components, the exceptions being the white corrugated fresh gas hose and the grey bodied plastic vacuum control block. However, the system can be supplied with an autoclavable (cream) fresh gas hose if requested at time of ordering. All latex free.

Porter Instruments recommend removing the inner liner from the outside mask and washing both masks in soap and water. Thermal washer disinfectors are fine for the preliminary wash. Use of chemicals used in cold sterilisation techniques is not recommended. Whilst they do not degrade (no ph sensitivity) the silicone of the mask, they can leave a residue on the mask that can irritate or even chemically ‘burn’ the patient’s skin if the mask is not properly rinsed, an example of this is Microzid. Prolonged use of these can also cause discoloration of the mask from grey to a ‘mushroom brown’. Ultrasonic cleaners can be used if required. The grey coaxial hose has an opening of 9mm. The manufacturers do not describe this as a ‘lumen’ and state that steam penetration is possible and adequate.

Steam sterilisers with the following cycle times are acceptable:

• 134 degrees Celsius for 3.25 mins @ sterilisation temp
• 121 degrees Celsius for 15.5 mins @ sterilisation temp

Matrx ANS) Autoclavable Nitrous Scavenger System

The manual states that ‘Most A.N.S. components are autoclavable. CAUTION: When autoclaving A.N.S. components, Matrx recommends following the specific protocol of the using service or the steriliser manufacturer. Temperatures consistent with silicone, Ultem (polyetherimide) and polysulfone, in the range of 120 degrees Celsius to 134 degrees Celsius can be used.’

The system should be disassembled, each tube and the scavenging cone system washed with a mild alkali detergent and all parts not precluded, autoclaved. Precluded parts include: white single-use nasal hoods and the scavenger control valve.
Note: This system can be used with blue (autoclavable) nasal hoods and white (Dynomite single patient use) nasal Hoods. All latex free.

Matrx Passive System

This system has been on the marketplace for approximately 40 years and is the only one designed to scavenge ‘passively’ i.e. air flow rate at the nasal mask of no more than 0.5 L/min, even when connected to an AGS System -
(w/air-brake in-line). It also had infection control issues, as the only component capable of being autoclaved was the blue nasal hood. Therefore, a decision was made by the manufacturer to withdraw this system in September 2009.

Accutron Scavenger System

This system is similar in appearance to the Porter brown except the tubing is white, not grey. However, the main differences are with the nasal hood arrangement and the vacuum control block is placed in-line with the vacuum hose. This system uses single nasal hoods , with a clear collector cap arrangement. The manufacturer states “ The scavenging system is shipped non-sterile. The white high-density tubing, clear scavenging hub and white fittings are autoclavable. Do not exceed 250 degrees Fahrenheit for 15 minutes.
CAUTION: Detach large corrugated tube and spiral vacuum tube before autoclaving. Do not autoclave the spiral vacuum tube containing the vacuum flow control valve.”

These instructions effectively mean that Accutron are recommending a temperature of 121.11 degrees Celsius. There have been reported problems with autoclaving of the nasal hoods and clear collector caps, resulting in distortion after several autoclave sessions
This system can also be used with the Accutron brightly coloured, scented single patient use nasal hoods and these are not autoclavable. All latex free.

Section 3. General Observations

The new HTM 01-05 Decontamination in primary care dental practices does not mention R A (or I.S.) Sedation equipment at all. However, the Audit Tool; ‘Assessing Implementation of HTM 01-05: Decontamination in Primary Care Dental Practices and related infection prevention and control issues’ will.

Section 5 Management of Dental Medical Devices – equipment and dental instruments Heading Inhalation Sedation Machines (ISM) (ref 2) contains the following questions:

27) Are IS Flowmeters used and maintained in accordance with OEM (Original Equipment Manufacturer) or Suppliers instructions?

28) Are IS breathing systems (mask and tubing’s) used in accordance with Manufacturer’s or Suppliers instructions (Also please refer to Q14).

Q14 comes under the sub-heading of Other Medical Devices and asks: ‘Are single-use items only used for single treatment episode and disposed of following use?.

Comment on Disposable: Most breathing systems are designed to be autoclaved, but with the option of disposable, single patient use components. These range from nasal hoods and liners to coaxial hose. At the present time, no fully disposable active breathing system is available, however, an R & D programme is underway to develop one.

• Ref 1; ‘A Conscious Decision’ Department of Health 2003
• Ref 2; Local Self-Assessment Audit for Assessing Implementation of HTM 01-05. I.P.S. 2009

Mrs J E Pickles
Issue 1 10/09 Tel: 01535 652444