Dentsleeve passage of catheters News Contact Us  
About Us Products Technical Information Orders Library  
Clinical Catheters Customised Catheters Perfusion Pumps

Library > Further Information > Passage of catheters

Dentsleeve Technical Note 5 Version 2 - Passage of catheters

Strategies for transnasal or oral passage of catheters

Successful introduction and positioning of catheters is an essential requirement for manometric recordings. The manometrist needs to evaluate the best approach for achieving this, especially in patients with motor disorders. In some settings, intubation can only be achieved through the use of catheters with design features that are specially tailored to the situation.

This technical note aims to inform Dentsleeve customers about the options for intubation. We are happy to advise customers on how designs can be best matched to the technical challenges of a specific situation, in order to maximise the chances of success.

Minimisation of discomfort
of intubation

The advantages of a well-tolerated intubation are self-evident. Tolerance of an intubation will be maximised if attention is paid to the following factors:

Use of the smallest possible diameter catheter

Catheter diameter has a major impact on the tolerance of intubation.

The catheter used for any particular measurement should have the smallest diameter consistent with reliable achievement of the measurements required.

It should be noted though, that in some settings, there are significant limitations from the flexibility of narrow diameter extrusions.

Dentsleeve has developed a range of unusually small diameter extrusions: see Section 2 Manometric extrusions (pages 4-16).

For routine oesophageal manometry we recommend our 4.0 mm diameter spec #114 extrusion catheters as the best compromise of properties.

Use of catheters made
of flexible materials

Catheters made of very stiff materials resist flexion around the curvature of the pharynx.

This stiffness results in poor tolerance of the catheter because it causes excessive mechanical stimulation of the pharynx.

Softer and thinner catheters are associated with greater comfort.

Contrary to what might be expected, the smaller diameter and softer catheters made by Dentsleeve still deliver excellent pressure rise rates (see Section 2 Manometric extrusions - pages 4-16).
Minimisation of manometric catheter movement during recording sessions

Repeated manipulation of a recording catheter causes considerable discomfort.

Recordings are best tolerated if they use an approach that minimises the amount of catheter manipulation. The sleeve and multiple side hole recording approach achieve this aim best.

Avoidance of pharyngeal
water infusion

Pharyngeal manometry is a very convenient way of monitoring for swallowing.

Interpretation of oesophageal manometric tracings demands that swallowing be monitored.

Pharyngeal water infusion can however, cause substantial discomfort and stimulation of swallowing.

A non-perfused, water-filled manometric channel can signal the occurrence of pharyngeal pressure waves generated by swallowing, but frequently does this unreliably.

Perfusion of the pharyngeal manometric side hole with air provides the best technical solution to manometric monitoring for swallowing(1). This is a standard feature on Dentsleeve pumps not provided
by others.

An air perfusion rate of between 2 and 4 ml per minute is effective, and the rate of air infused into the manometric channel is controlled by a hydraulic resistor in the same way as water perfusion is controlled.

A specially high value resistor is therefore needed to restrict air flow to the effective range.

Further explanation of pharyngeal air perfusion manometry is given in Section 5 - Perfused gas manometry (page 61).
Use of the transnasal intubation route

Transnasal intubation is generally tolerated better than transoral. This is discussed further immediately below.

Use of mucosal anaesthesia during intubation

Though local anaesthetic sprays are unpalatable, they improve the tolerance of intubation, especially through the nose.

Transnasal versus oral intubation

Oral intubation is used in some laboratories, but the disadvantages of this route substantially outweigh the advantages summarised below.

Positive for oral intubation

Catheters greater than 5mm diameter are easier to pass, and better tolerated

Less initial aesthetic "shock"

Positive for transnasal intubation

Less sensory disturbance over time

Less stimulation of swallowing and salivation

Easier and more secure catheter anchorage

More accurate position control

The smaller the diameter of the catheter the greater are the gains from transnasal intubation.

Methods of introduction of catheters

Catheters can be passed by the following means:

  • primarily pushing on the catheter shaft
  • primarily tugging from the catheter tip.

    These two generic approaches are sometimes used at different stages of a single intubation.


    Blind push intubation as far as the stomach

    This method relies on the rigidity of the catheter.

    Under normal circumstances, a relatively small amount of push is needed for oesophageal intubation, since motor mechanisms aid passage of the catheter across the sphincters and along the oesophageal body.

    It is easier to pass small diameter catheters (2.5 to 1.8 mm) by pushing in children and infants compared to adults, since the smaller diameter oesophageal and nasal lumina help prevent buckling and turning back of the catheter when it is pushed.

    The force of "push" intubation can be greatly increased and directed more effectively by passing a catheter over a previously positioned guidewire - see below - "principles of push intubation by passage of catheters over a guidewire", and Dentsleeve Technical Note 6 - Guidewire assisted passage of catheters.

    The force of "push" intubation that can be applied with a particular type of catheter can also be increased by stiffening it - see below - "stiffening of manometric catheters".


    Gravity tug intubation

    With this intubation approach, forward movement of the catheter depends on the development of forces at the catheter tip itself.

    The modest gravitational tug of a weighted tip is sufficient to pull a soft, medium to small diameter (3.5 to 1.8 mm) catheter through the nasal cavity, pharynx, oesophagus and stomach. The effect of gravitational tug can be maximised by:

    Posturing of the patient to maximise the effect of gravity

    When the weight is being passed through the nose, the head is held back, and then when it is traversing the pharynx, oesophagus and upper two-thirds of the stomach, the patient sits or stands.

    Passage of the weighted tip into the distal antrum under the influence of gravity is assisted by positioning the patient in the right lateral position.

    Controlled introduction of the catheter at the nostril

    Sufficient length needs to be available for the weighted tip to move freely, so that the catheter needs to be introduced in a stepwise manner at the nostril.


    Freeing of the tip weight from entrapment

    The relatively modest tug of a weighted tip may lead to its failure to advance by merely being caught up in a mucosal fold.

    This can be minimised by the use of vibration and by maximisation of the gravitational tug - see immediately below.

    Augmentation of gravitational tug of the tip weight

    This can be done by having the patient make rapid body movements against gravity during intubation.

    Most importantly, passage of the tip weight into the proximal antrum can be greatly assisted by having the subject jump on the spot.

    Once the tip has reached this position, its further passage can be aided by gentle shaking of the abdomen with the patient in the right lateral position.

    Other methods of applying tug to catheter tips

    Tug can also be applied to the tip of an catheter by inflation of a small (10 to 15 mm) diameter tip balloon (see pages 49-50).

    Balloon-aided intubation has only been evaluated for the small intestine, and in this setting is a very valuable aid to the achievement of deep small intestinal or colonic intubation via the nose or mouth.(2,3)

    Balloon and gravity tug intubation depends substantially on normal sphincter relaxation and existence of some propulsive motor activity in non-sphincteric regions.

    The greatest levels of tip tug are achieved by towing an catheter tip with an endoscope - see below - "tug intubation by endoscopic towing".


    Push intubation by passage of catheters over a guidewire


    Catheters can be pushed into place over a guidewire that has been placed endoscopically or fluoroscopically.

    Endoscopic placement of a guidewire has the disadvantage of requiring the re-routing of the wire through the nose if the studies are to benefit from the transnasal route.

    The success of push intubation over a guidewire depends mainly on the use of a slip tube and specially chosen and designed Dentsleeve catheters.
    The use of a slip tube is explained in Dentsleeve Technical Note 6.
    The guidewire needs to be sufficiently stiff to guide the catheter during its passage. Excessive bowing of the guidewire can readily lead to backwards displacement of the guidewire tip.

    For adults, transpyloric intubation requires a stiff guidewire, at least 1mm in diameter.

    We have insufficient experience of this mode of intubation to make any comment on the smallest suitable guidewire for use in this way in children.

    When guidewires are used for this application they must be placed and manipulated by adequately qualified people who are alert to the potential for perforation.

    Catheters need to be designed specifically for passage over a guidewire, with an opening for the guidewire channel at the end of the catheter.

    The largest possible diameter guidewire channel should be used by careful selection of the extrusion type for the catheter, to make passage on a guidewire, and its removal as easy as possible (see below).

    Tip weights are incompatible with the design of most catheters intended for passage over a guidewire, but tip balloons are technically feasible in such catheters.

    Push intubation of
    stiffened catheters

    The rigidity, and so the push that can be transmitted to the tip of the catheter can be greatly increased by incorporation of a stiffener along the length of the catheter.

    Catheters can be stiffened permanently by installation of a length of nickel-titanium wire within one manometric channel.

    Alternatively, a closed channel can be used to insert a removable guidewire for situations when stiffening is required. If the guidewire is to be removed during measurement, a slip tube will usually be necessary for all but oesophageal catheters - see Dentsleeve Technical Note 6.

    Stiffening of catheters is especially useful in some measurement settings in which small diameter (2.5 to 1.8mm) catheters are usedsee commentary on intubation of individual sphincters below.

    When catheters are stiffened, they must be used in the knowledge that they can apply substantial force to the tip of the catheter thereby increasing the risk of perforation.

    Difficult intubations with stiffened catheters should always be approached with great caution, and whenever possible, be done with concurrent fluoroscopy.


    Tug intubation by
    endoscopic towing

    Endoscopes can be used to tug catheters into the duodenum.

    The tip of the catheter is equipped with a loop of strong black silk which can be grasped by endoscopic grasping forceps.

    The loop should be long enough to allow the forceps holding the loop, to be withdrawn into the endoscope, without the tip of the catheter being pulled up against the lens of the endoscope.

    It is recommended that the catheter be passed firstly into the stomach via the nose.

    The endoscope is then passed through the mouth into the stomach, and the suture loop at the tip of the catheter is located and grasped with the forceps.

    The endoscope and the catheter are then directed into the duodenum after the grasping forceps have been withdrawn safely into the endoscope channel.

    The catheter is driven as far as possible into the duodenum with the endoscope.

    The endoscope is then withdrawn, but friction between the catheter and the endoscope is a major limitation of this method. This friction tends to lead to withdrawal of the catheter with the endoscope unless special precautions are taken to minimise this friction, and to break the adhesion between the endoscope and the catheter with each withdrawal.

    The catheter can be made more resistant to unwanted withdrawal through friction with the endoscope by being stiffened with a guidewire positioned within a sealed channel of the catheter. This guidewire needs to be relatively stout.

    Other measures are usually also necessary to minimise or overcome the friction between the endoscope and the catheter.

    Upper oesophageal and oesophageal body intubation

    This usually poses no difficulty, apart from patients who have a cricopharyngeal bar or a Zencker's diverticulum.

    In these patients, the upper oesophageal sphincter opens poorly and is very sensitive.

    In patients with Zencker's diverticulum, there is the added hazard of the tip of the catheter passing into the diverticulum and then rupturing it.

    The hazards and mechanical resistance of passage of a catheter across the upper oesophageal sphincter in patients with cricopharyngeal bars and Zencker's diverticulum can be minimised by passage of the catheter over a guidewire that has been carefully placed previously with the aid of fluoroscopic control.(4)

    Catheters need to be specifically designed for passage in this manner, and should only be passed under fluoroscopic control.

    Lower oesophageal sphincter (LOS)

    When the LOS relaxes normally, it is rare to encounter any difficulty with passage of even a very flexible and soft catheter across the LOS.

    In a non-dilated, but poorly relaxing oesophagus, catheter passage depends significantly on development of an effective push force across the lower oesophageal sphincter. This can be achieved by:

  • use of an inherently stiff catheter

  • stiffening of an catheter with a fixed or removable stiffener

  • passage over a guidewire placed fluoroscopically or endoscopically

    The LOS relaxes poorly not only in patients with achalasia or a tight fundoplication, but also during anaesthesia in normal humans and animals. In these settings, successful passage of catheters may require that they be stiffened.

    Oesophageal dilatation or deformity can make LOS intubation difficult, because the catheter tip may not engage effectively with the lumen at the upper end of the sphincter.

    In addition oesophageal dilatation can make it difficult to transfer push effectively to the catheter tip, because of bowing or even turning back of the catheter within the oesophageal lumen.

    Usually, Dentsleeve oesophageal catheters designed for passage over a guidewire do not require a slip tube.

    The strategies for intubation outlined above should be considered on a case-by-case basis, always in the light of a careful assessment of the risks of intubation associated with each approach.


    Gastric and pyloric intubation

    Passage of a catheter into the distal antrum can be achieved relatively easily with push or tug methods, regardless of the presence or absence of a motor abnormality.

    In individuals with normal gastric motility, transpyloric passage of an catheter is also usually easily achieved with tug from a weighted tip as outlined in the section that deals with tug intubation above.

    Tip weight tug intubation has a substantial failure rate in individuals with gastroparesis.

    Blind push intubation is a relatively poor option for traversing the pylorus for the following reasons:

  • the catheter tip cannot be steered effectively to engage in the pylorus

  • push is transferred fairly poorly to the catheter tip.

    When a radiologist expert in fluoroscopically controlled pyloric intubation is available, this is a very efficient option, provided an appropriately stiffened catheter is used.

    Push intubation is impossible with standard catheters that have pyloric sleeves incorporated into them, since these catheters have a specially designed maximally flexible segment just distal to the sleeve.

    The flexibility of this segment allows the catheter to traverse the acute curvature of the proximal duodenum without applying leverage forces to the sleeve when it is correctly positioned in the pylorus, but makes it impossible for push to be transmitted to the tip of an unstiffened catheter.

    Consistently successful passage of catheters into the distal duodenum of patients with significant gastroparesis requires close attention to detail and special tailoring of catheter design to the method of intubation used. Options to be considered are:

  • push intubation with a specially stiffened catheter with subsequent withdrawal of the stiffener if a pyloric sleeve is to be used - a slip tube is required.

  • push intubation over a previously positioned guidewire - a slip tube is required.

  • endoscopic tug intubation.

    The options listed are dealt with in more detail in sections of this commentary above.

    Dentsleeve Technical Note 6 deals with slip tubes and their use.

    Small intestinal and colonic intubation

    Push intubation of any type is relatively ineffective beyond the ligament of Treitz.

    Tug intubation with tip weights is also a relatively ineffective approach beyond the ligament of Treitz.

    The best option is the use of a tip balloon to provide tug on the end of the catheter by stimulation of propulsive motor patterns(2,3).

    It is unclear whether it is best to wait for the balloon to pass into the duodenum before it is inflated, but this is the usual practice and so is recommended.

    Colonic manometric catheters may also be tugged retrogradely by colonoscopy. There is no reported experience with push intubation over a guidewire, using a slip tube.


    1. Omari et al. Gut (1997) 40:370-375
    2. Fone et al. Gastroenterology (1990);98:568-575
    3. Kerlin et al. Aust NZ J Med (1983);13:591-593
    4. Cook et al. Gastroenterology (1992);103:1229-1335



    Intubation of the upper gastrointestinal tract can sometimes pose a very significant challenge. The various strategies outlined above all carry significant risks if they are used inadvisedly, or in an unskilled manner. The clinician responsible for the intubation must assume total responsibility for the safety of the use of the methods outlined above.

    Potential Application and Technical Challenges

    This Technical Note provides more detailed guidance on methods of "push" intubation. For general information, please see our Technical Note 5 Version 2 - Passage of catheters.

    Users of catheters sometimes wish to stiffen catheters with removable guidewires, or to pass catheters over guidewires that have already been placed radiologically or endoscopically.

    Once a catheter has been correctly positioned, there may be a need to remove the guidewire.

    Passage over a guidewire or removal of a guidewire is frequently difficult or impossible for catheters for use in the distal stomach, duodenum or small intestine because friction between the catheter material and the guidewire is too high. This is a major limitation even when a channel is large enough to easily accommodate the diameter of a guidewire.

    Excessive friction results when the catheter is curved around bends in the gut, even though it will be possible to insert and remove a guidewire from a manometric catheter channel when it is held straight prior to insertion.
    Slip coatings on guidewires are not usually sufficiently effective to overcome these frictional problems.

    Silicone rubber especially has a high "grippiness" to guidewire stiffeners, but this limitation can be overcome by simple strategies outlined below.
    Do Not Use Lubricants!

    It is of paramount importance that silicone rubber catheters do not contact silicon oil or grease. This is absorbed by silicone rubber, causing it to swell and weaken, making the catheter unserviceable and potentially dangerous.

    Other lubricants may attack the catheter materials and are fairly ineffective, and so are best avoided.

    Passage Over a Guidewire For Oesophageal Manometry

    This is usually only needed in patients who have moderate to severe oesophageal dilatation or a diverticulum.

    Because of the straightness of the oesophagus, and the relative shortness of the catheter, intubation is usually possible over a previously placed guidewire without a slip tube. The catheter used must have a large channel that opens at the tip.

    Passage Over a Guidewire For Manometry In Regions Other Than the Oesophagus

    Users of Dentsleeve silicone rubber catheters must use a slip tube insert for this procedure.

    A slip tube is a thin-walled Teflon tube just small enough to fit snugly within a manometric catheter channel large enough for a guidewire. The slip tube is inserted into the catheter before each intubation and retained within the guidewire channel of the catheter throughout the measurement. It is removed from the catheter after extubation, and before the catheter is cleaned and autoclaved.

    The natural low friction of the slip tube allows the guidewire to move freely within it, despite quite tight curvature of the catheter, whether it is being pushed into place over a guidewire or if the guidewire is being withdrawn from a positioned catheter.
    Choice of Catheter Extrusion Suitable for Use With a Slip Tube

    A catheter with a large channel of at least 1.5mm diameter should be selected. Our 12+1 E56 and our 20+2+1 E55 are best suited, as they allow for the largest guidewire diameters. The slip tube supplied is tailored to the specific extrusion.

    Catheters to be used for passage over a guidewire with a slip tube must be made for this purpose, and have three main features:

    1) The large channel opens at the catheter tip

    2) The diameter of the large channel is stepped down at the tip to retain the slip tube within the catheter, yet allow free movement of the guidewire into the channel through the catheter tip

    3) The single lumen tube connected to the guidewire channel at the junction between the multi-lumen extrusion and the single lumen connector tubes is made only 20cm long.

    Naturally, a large channel assigned for use with a slip tube is not available for another purpose, except for use as an infusion/aspiration channel at its tip, if the guidewire is removed.

    Infection Control

    Slip tubes will be supplied for specific catheters to a length equal to the total length of the guidewire channel.

    Dentsleeve has not validated any disinfection process for the slip tubes. These are therefore offered as single use items.
    Slip Tube Installation

    For greatest ease of use, the following sequence of steps is recommended:

    1) Insert a guidewire into the slip tube

    2) Inject 1-2mL of isopropyl alcohol into the catheter guidewire channel. Do not flush. This briefly makes the silicone rubber slippery.

    3) Pass the guidewire-stiffened slip tube down the catheter guidewire channel, with the catheter held straight on a bench. Pass the slip tube until it reaches the reduced diameter portion of the guidewire channel at the catheter tip. Pass the final centimetre or so of slip tube by milking the connector tube, so that the slip tube is fully within the guidewire channel.

    4) Remove the guidewire.

    5) Flush the guidewire channel gently with 20mL of water, then 20mL of air to remove all traces of isopropyl alcohol.

    The catheter is now ready for passage over the guidewire.

    Slip Tube Removal

    This must be done directly after extubation. Lay the catheter out straight on a bench. Milk the slip tube out of the connector tube fitting by stretching and pinching the connector tube. Once the slip tube protrudes from the connector tube fitting, gently withdraw it from the catheter. This is easier if an assistant holds the tip of the catheter.


    Intubation with processes described above requires specialised training and judgement about the specific procedure being performed and individual patient characteristics. Choice of guidewire will influence the safety and efficacy of the procedure. Dentsleeve cannot be held responsible for any injury resulting from the use of slip tubes and guidewires.


    Dentsleeve International Ltd


    Technical Notes