The effect of a heat and moisture exchanger on gas flow in a Mapleson F breathing system during inhalational induction

Mapleson breathing systems are used for delivering oxygen and anaesthetic agents and to eliminate carbon dioxide during anaesthesia. They consist of different components: Fresh gas flow, reservoir bag, breathing tubes, expiratory valve, and patient connection. There are five basic types of Mapleson system: A, B, C, D and E depending upon the different arrangements of these components. Mapleson F was added later. For adults, Mapleson A is the circuit of choice for spontaneous respiration where as Mapleson D and its Bains modifications are best available circuits for controlled ventilation. For neonates and paediatric patients Mapleson E and F (Jackson Rees modification) are the best circuits. In this review article, we will discuss the structure of the circuits and functional analysis of various types of Mapleson systems and their advantages and disadvantages.

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“…So most of the fresh gas will enter expiratory limb leading to wastage of fresh gases and delaying induction by inhalation agents. [242526]…”

Section: Mapleson F Systemmentioning

confidence: 99%

Mapleson′s breathing systems

Kaul

Mittal

2013

Indian J Anaesth

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“…The work of breathing increases when HMEFs are used [113]. The resistance to gas flow of an HMEF added to a Mapleson F breathing system can cause a delay in the induction of anaesthesia [114]. The addition of an HME can cause hypercapnia if the internal volume of the HME is too large [115].…”

Section: Use Of Hmes and Filters With Paediatric Patientsmentioning

confidence: 99%

Heat and moisture exchangers and breathing system filters: their use in anaesthesia and intensive care.  Part 2 – practical use, including problems, and their use with paediatric patients

Wilkes

2010

Anaesthesia

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SummaryHeat and moisture exchangers and breathing system filters are intended to replace the normal warming, humidifying and filtering functions of the upper airways. The first part of this review considered the history, principles of operation and efficiency of these devices. The aim of this part of the review is to summarise recent guidelines on the use of these devices and outline the problems that can occur. In particular, the effect of these devices on gas analysis, dead space, resistance to gas flow and blockage of the breathing system is considered. In children, it is important to consider the addition of dead space and resistance to gas flow. A body weight of 2.5 kg is probably the lower weight limit for use with heat and moisture exchangers, and 3 kg for filters. The resistance to gas flow of a heat-and moisture-exchanging filter added to a Mapleson F breathing system can cause a delay in the induction of anaesthesia.

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“…This gradient is suf®cient to allow diversion of fresh gas down the expiratory limb, resulting in failure or delay in gas induction. Goddard reported dif®culty in performing gas inductions when using an Ayres T piece with a ®lter, and this technique 34 was the cause of concern for Marcus and colleagues. 45 71 Da Fonseca and co-workers recommend that the HME should be removed from the Mapleson F breathing system until inhalation induction is complete, or that the reservoir bag is completely occluded unless an effective seal is obtained with the mask.…”

Section: Delay or Failure Of Gas Inductionmentioning

confidence: 99%

Hidden hazards and dangers associated with the use of HME/filters in breathing circuits. Their effect on toxic metabolite production, pulse oximetry and airway resistance

Lawes¹

2003

British Journal of Anaesthesia

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Current airway dust ®lter technology emanates from the USA mining industry during the 1930s. It was further developed and improved by the USA military during World War II to prevent workers from inhaling very ®ne radioactive particles in the nuclear industry. These later ®lters we now recognize as high ef®ciency particulate air ®lters (HEPA).The ef®ciency of ®lters varies according to the number and size of particles they capture. Filters may be classi®ed commonly as 95, 99.95, and 99.97% ef®cient (95, 99 and 100, respectively). The higher the ef®ciency the higher the classi®cation number used. The ef®ciency of ®lters may also be affected by volatile chemicals which may be inhaled with the particles. Industrial ®lters which are categorized by the above system may also have a pre®x of N, R, or P; N for Not resistant to oil, R for Resistant to oil, and P for oil Proof; thus, a ®lter would be classi®ed as for example a P100. Requirements for military and environmental biohazard ®lters are based on these classi®cations and surprisingly may only achieve 95% ef®ciency.A generally perceived increased threat from biological hazards that may be inhaled, including bioterrorism threats, especially in hospital environments, has increased interest in respiratory ®lters. 94 Protecting personnel from inhaled biological hazards requires a ®lter ef®ciency of several orders of magnitude greater than the industrial dust ®lters used in respirators alluded to above. As few as 10 inhaled smallpox viruses may be suf®cient to infect patients with the disease. 94 This has resulted in the sub-classi®cation of HEPA ®lters into true HEPA ®lters and HEPA type ®lters. A further sub group has also developed. ULPA ®lters (Ultra Low Penetration Air) and`absolute' ®lters are designed for industrial applications such as microelectronic clean rooms, but have too high a resistance for medical breathing apparatus.All HEPA ®lters are manufactured from glass ®bre materials supported on a rigid frame. In order to reduce resistance to air¯ow and increase ef®ciency, the surface area is increased by pleating. Filtration is achieved for larger particles (>0.3 m) by inertial impaction and interception; smaller particles are captured by Brownian diffusion. The size of particles used to test ®lters is measured in microns. Microns are units used for particles that can be seen with a light microscope. A micron is a thousandth of a millimeter, which is in turn a thousandth of a meter (1 m=1000 nm or 0.001 mm). The variation in ®ltration ef®ciency is tested by the British BS3928 Sodium Flame method and the USA Hot DOP method. The most dif®cult particle size to capture by ®ltration is a particle of 0.3 m as at this size the effects of inertial impaction, interception and Brownian motion are least effective. Particles of 0.3 m are also most likely to be deposited in the lungs if inhaled. The di-octyl-phthalate (DOP) test, used for testing the ef®ciency of ®lters, takes advantage of the properties of DOP. In particulate form, DOP has a constant mean diameter of 0.3 ...

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The effect of a heat and moisture exchanger on gas flow in a Mapleson F breathing system during inhalational induction

Cited by 4 publications

References 6 publications

Mapleson′s breathing systems

Mapleson′s breathing systems

Heat and moisture exchangers and breathing system filters: their use in anaesthesia and intensive care.  Part 2 – practical use, including problems, and their use with paediatric patients

Hidden hazards and dangers associated with the use of HME/filters in breathing circuits. Their effect on toxic metabolite production, pulse oximetry and airway resistance

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The effect of a heat and moisture exchanger on gas flow in a Mapleson F breathing system during inhalational induction

Cited by 4 publications

References 6 publications

Mapleson′s breathing systems

Mapleson′s breathing systems

Heat and moisture exchangers and breathing system filters: their use in anaesthesia and intensive care. Part 2 – practical use, including problems, and their use with paediatric patients

Hidden hazards and dangers associated with the use of HME/filters in breathing circuits. Their effect on toxic metabolite production, pulse oximetry and airway resistance

Contact Info

Product

Resources

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Heat and moisture exchangers and breathing system filters: their use in anaesthesia and intensive care.  Part 2 – practical use, including problems, and their use with paediatric patients