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Introduction
The Rapid RhinoTM pneumatic nasal tampon (Applied Therapeutics Ltd, Glenfield, United Kingdom) consists of an inflatable nasal cuff (balloon) with a haemostatic coating (Gel Knit(TM) fabric; Acordis Speciality Fibres, Coventry, United Kingdom), a valve and a pilot cuff. With the exception of one case of an ingested Rapid Rhino nasal pack,1 these devices have been demonstrated to be safe, comfortable and effective in achieving haemostasis in the nasal cavity.2-4 The balloon is inflated with air, as this provides more gentle compression of the nasal mucosa than the larger pressures that can be generated using liquids. Epistat and Brighton balloons spontaneously deflate after air insufflation,5 as do Teflon(TM)- and silicone-coated Foley catheters when used for nasal packing.6 The balloon in the Rapid Rhino nasal pack is manufactured by Applied Therapeutics Ltd from medical grade polyvinylchloride, and the valve is assembled using an 'O' ring and a stainless steel spring so that the product is leak-proof even at very low pressures.
However, the authors noticed that, when used in vivo, the pressure in the pilot cuff could diminish with time (as assessed by tactile feeling); ward patients had also suggested that depressurisation may be occurring. On occasion, we observed that further inflation was necessary to control epistaxis after the pack has been in situ for a while.
We wished to study the in vivo behaviour of Rapid Rhino packs and to characterise the rate of depressurisation and/or leakage, so that we could anticipate when further monitoring and possibly inflation of the Rapid Rhino pack may be necessary. Unfortunately, assessment of the pressures and volumes of Rapid Rhino packs is challenging because the pack holds only a small volume of air. Any air lost when connecting the measuring apparatus would therefore be significant. Investigating the in vivo behaviour of Rapid Rhino packs therefore required assessment of any potential air loss due to the measurement apparatus, in addition to studying air pressures and volumes within the packs themselves.
Materials and methods
Air pressure in 7.5 cm Rapid Rhino nasal packs was measured using a low reading Portex pressure gauge (Applied Therapeutics Ltd, Glenfield, United Kingdom) and a Y piece connector with a removable one-way...