Assessment of a hygroscopic heat and moisture exchanger for paediatric use

Wilkinson, K. A.; Cranston, A.; Hatch, D. J.; Fletcher, M. E.

doi:10.1111/j.1365-2044.1991.tb11502.x

Cited by 11 publications

(8 citation statements)

References 13 publications

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“…Wilkinson and co-workers investigated the resistance to¯ow for 12 hygroscopic HME in order to determine the possible effects on the work of breathing during steady state anaesthesia. 114 They found the dead space to be equal to standard catheter mounts (12 ml), and they comment that resistance to breathing was`low, compared to other anaesthetic equipment'. The use of some HMEFs in paediatrics has been restricted by the dead space of the devices.…”

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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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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“…8 11 A modern paediatric HME adds little deadspace or resistance to flow even when fully saturated. 117 Recently, more sophisticated devices have become available that not only have heat and moisture exchanging qualities but that also act as an effective barrier to bacteria and viruses. These heat and moisture exchanging filters (HMEF) use a hydrophobic membrane composed of coated ceramic fibres, which is deeply pleated to maximize surface area and absorption surface.…”

Section: Humidification Of Inspired Gasesmentioning

confidence: 99%

Equipment and monitoring in paediatric anaesthesia

Booker

1999

British Journal of Anaesthesia

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“…It has been demonstrated that the endotracheal tube is the individual component with the highest contribution to airway resistance . Also, breathing circuit filters were shown to contribute—to a lesser extent—to the artificial resistance . However, research on other components of the breathing circuit is lacking or outdated considering the continuously growing product range.…”

Section: Introductionmentioning

confidence: 99%

Pressure‐flow characteristics of breathing systems and their components for pediatric and adult patients

Wenzel

Schumann

Spaeth

2017

Pediatric Anesthesia

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Summary Background Breathing circuits connect the ventilator to the patients’ respiratory system. Breathing tubes, connectors, and sensors contribute to artificial airway resistance to a varying extent. We hypothesized that the flow‐dependent resistance is higher in pediatric breathing systems and their components compared to respective types for adults. Aims We aimed to characterize the resistance of representative breathing systems and their components used in pediatric patients (including devices for adults) by their nonlinear pressure‐flow relationship. Methods We used a physical model to measure the flow‐dependent pressure gradient (∆P) across breathing tubes, breathing tube extensions, 90°‐ and Y‐connectors, flow‐ and carbon dioxide sensors, water traps and reusable, disposable and coaxial breathing systems for pediatric and for adult patients. ∆P was analyzed for usual flow ranges and statistically compared at a representative flow rate of 300 mL∙s−1 (∆P300). Results ∆P across pediatric devices always exceeded ∆P across the corresponding devices for adult patients (all P < .001 [no 95% CI includes 0]). ∆P300 across breathing system components for adults was always below 0.2 cmH2O but reached up to 4.6 cmH2O in a flow sensor for pediatric patients. ∆P300 was considerably higher across the reusable compared to the disposable pediatric breathing systems (1.9 vs 0.3 cmH2O, P < .001, [95% CI −1.59 to −1.56]). Conclusion The resistances of pediatric breathing systems and their components result in pressure gradients exceeding those for adults several fold. Considering the resistance of individual components is crucial for composing a breathing system matching the patient's needs. Compensation of the additional resistance should be considered if a large composed resistance is unavoidable.

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Assessment of a hygroscopic heat and moisture exchanger for paediatric use

Cited by 11 publications

References 13 publications

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

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

Equipment and monitoring in paediatric anaesthesia

Pressure‐flow characteristics of breathing systems and their components for pediatric and adult patients

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