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Perfused gas manometry


  • Pharyngeal manometry is useful for monitoring of swallowing, but pharyngeal water infusion can cause irritation and so swallowing, as well as have effects on oesophageal sphincter pressure.

  • Dentsleeve has developed the use of air as a perfusate for pharyngeal manometric channels used for monitoring of swallowing.

  • Dentsleeve MK II and MK III manometric perfusion pumps provide for one air perfusion circuit. The information in this section relates primarily to Dentsleeve manometric infusion pumps.

  • Air perfusion rate can be controlled with the same type of hydraulic resistor as is used for water perfusion but this needs to have a high resistance to flow or the air flow rate will be excessive.

  • For a particular hydraulic resistor, air flow rates are 100 times its water flow rate at the same driving pressure.

  • Air perfusion is especially useful for monitoring of swallowing in neonates and small children in whom the possibility of reflex stimulation and aspiration of infused water is especially high.

  • The air perfusion channel of Dentsleeve Mark II and III pumps is supplied with compressed air via a sidearm from the regulated pressure supply to the perfusate reservoir, which is normally set to 15 psi or 100 kpa.

    Performance data

    The diameter of the manometric channel influences the pressure rise rate achieved with air perfusion, but the volume of the pressure transducer chamber is the most important factor. The smaller the volume the better.

    Pressure transducer chamber volumes can vary widely amongst different transducers, but nearly all modern pressure transducers are acceptable.

    Pressure rise rates with gas perfusion are summarised in the table below. More detail is given for Dentsleeve manometric extrusions in the performance data for each extrusion (see Section 2, Manometric extrusions, pages 4-16).

    Pressure rise rates sufficient for adequate swallow monitoring are usually achieved with gas infusion rates of from 2-8 ml/min dependent on the diameter of the manometric channel, its length and pressure transducer design.

    Accordingly, Dentsleeve hydraulic resistors with a high resistance value are required, ranging from an HRE/ST/2 or HRE/CO/2 resistor (2 ml/min) to an HRE/ST/8 or HRE/CO/8 resistor (8 ml/min). As can be seen from the above, the resistor product number actually gives the air perfusion rate in ml/min.

    Dentsleeve Mark II and III manometric perfusion pumps have a special air perfusion manifold and red colour-coded pinch clamp or white and red pinch valve.

    To avoid any possibility of reduction of inspired oxygen levels by pharyngeal nitrogen infusion, we recommend that compressed air be used as the gas for perfusion and so also for pressurisation of the perfusate reservoir.


    Although air perfusion can achieve remarkably high pressure rise rates, this is only recommended for pharyngeal manometry specifically for monitoring of swallowing.

    Gas perfusion of manometric channels in any place other than the pharynx is not recommended as it will cause delivery of significant amounts of gas over time.

    * These data are for a 140 cm long assembly with an air perfusion pressure of 15psi or 100 kpa, measured with a transducer with a chamber volume of 0.2 ml


    An hydraulic resistor of the correct value must be connected between the air perfusion manifold tap and the pressure transducer to limit air flow to the required rate. In no circumstances should the air perfusion manifold be connected directly to the manometric assembly as this will deliver an excessive volume of air down the manometric assembly. The air perfusion pressure must be the same as the perfusate reservoir driving pressure.The design of Dentsleeve manometric infusion pumps ensures that this is the case.

    Gas perfusion is intended solely for pharyngeal swallow monitoring.


    Dentsleeve International Ltd


    Products and techniques for perfused manometry