Applicator for pulsoxymetric sensor with torque limiter

Details Applicator for pulsoxymetric sensor with torque limiter Applicator for pulsoxymetric sensor with torque limiter

1999-03-26

2001-03-13

Winakur, Eric F. (Department: 3736)

Surgery

Diagnostic testing

Measuring or detecting nonradioactive constituent of body...

C600S376000

Reexamination Certificate

active

06201978

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to an applicator for sensors used in the field of medicine.
2. Description of the Related Art
In the field of medicine it is known to insert sensors, especially spiral sensors, into the skin of the patient by rotation, i.e., to screw a spiral sensor with its usually very sharp front end into the skin of the patient in a spiral type motion consisting of application-pressure and torque.
This is the case for example with the wide-spread fetal scalp electrodes which are used to anchor a sensor in the scalp of an unborn child in order to measure the ECG of the unborn child after membranes are ruptured.
Optical sensors can be housed in the tip of such spiral sensors, too, for example for fetal pulse oximetry, with the help of which a direct monitoring of the oxygen saturation in the blood of the unborn child can be established.
Such a sensor is disclosed in the DE-C 3810 008. C1
Since the spiral sensors are applied at a location which is out of view, that is to say behind the vagina of the mother within the uterus, it is a problem for the user to apply these spiral sensors with the correct amount of torque. If too much of a torque is applied, injuries of the fetal scalp are possible as well as a damage of the sensor and the applicator respectively or the perfusion at the site of the application can be restricted by too high an axial pressure of the sensor relative to the patient.
If too small of a torque is applied, the sensor is only poorly anchored in the skin of the patient and it comes loose due to the dynamic stresses occurring during the delivery and the vaginal examinations during the delivery respectively. Moreover too weak an application results in distortions of the signals derived from the sensor.
The application of the correct torque gets even more difficult because the sensor is located at the front end of a thin, long plastic rod or plastic tube respectively and because the user is able to turn only the rear end of this rod-like applicator. With a 20 cm long but just 2 or 3 mm thick rod the bending and the torsion of this rod-like applicator limits the user's feeling for the correct torque.
It is therefor the object of the present invention to provide an applicator which limits the torque during the insertion of the sensor into the tissue of the patient at least in respect to a maximal torque on the one hand, but on the other hand guarantees a necessary minimal torque during the application as well.
Thus the minimal torque guaranteed by the torque limiter may coincide with maximal torque to form a threshold value, that is to say, the very threshold value at which the torque limiter slips.
SUMMARY OF THE INVENTION
By providing the torque limiter in or on the applicator it is guaranteed that during the insertion no torque higher than the one the torque limiter is adjusted to can be applied.
In addition it is important that there is a perceptibility of the slipping through phenomenon of the torque limiter, that is to say, a device that allows to see the slip through phenomenon or at least to sense it with the operating hand.
A torque limiter of this type can be set to both a maximum and a minimum torque so that the torque limitation towards the minimal value avoids too soft an application and thus likewise too poor a fixation of the sensor in the tissue of the patient.
An especially simple embodiment of a torque limiter is represented by a sliding clutch which can be either mechanical, i.e. a force fitting or form-fitting operating by friction, as well as a magnetic, especially an electromagnetic, sliding clutch. The upper and lower limits of the torque can be easily adjusted, easily controlled and can be quickly deactivated in an easy manner too, by electrically influencing the magnetic forces of the sliding clutch.
At a first glance it would seem to be useful to position the torque limiter, for example the sliding clutch, as close as possible to the sensor, that is to say, at the front or the sensor end of the applicator, between the applicator and the sensor, in order to exclude the influence of the twistable applicator on the torque applied to the patient.
The drawback of this solution lies in the fact that the torque limiter is, during the fetal application, within the maternal body and thus under the influence of body fluids and mechanical pressure of the surrounding vagina, which could undesirably influence the function of the torque limiter.
If the torque limiter is positioned at the rear handling end of the applicator rod which is positioned outside of the body of the mother during the application, those interfering influences by body fluids and so on are avoided. In order to avoid a disturbance on the torque at the sensor caused by the twistable applicator rod which is positioned between torque limiter and sensor, the maximal torque applicable by the torque limiter must be lower than the torque by which the applicator rod collapses. A slight torsion of the applicator rod is harmless, since this torsion just causes an angle deviation between the handling end and the sensor end of the applicator rod but does not change the level of the torque having an influence on the patient, as long as this torque is the maximal applicable torque to which the torque limiter is preadjusted.
Such a fixed, preadjusted torque based on the torque limitation has a variety of advantages:
The evaluating devices linked to the sensor provide meaningful values since both the electric and the optic coupling to the tissue is more reliable, the influence on tissue perfusion of the patient remains minimal, its tissue physiology remains undisturbed and the traumatization of the tissue remains minimal. In addition the probability of tissue injuries of the patient becomes minimal so that all this can be used as a legal argument during a dispute with the patient since this torque limiter excludes the application of too high a torque and at the same time too low a torque. Further, the destruction of the sensor due to overstraining is avoided as well as a need for a reapplication after a too superficial fixation due to too small an application-torque. Also, less experienced users can feel safe beginning with the first experience with application.
When positioning the torque limiter in the handle of the applicator, especially a mating with a handle end is recommended since it can be disconnected from the single-use-applicator and is reusable.
Also the torque limiter can be positioned at the transition between the applicator rod and the grip part or between two parts of the handling part which are moveable relative to each other that is to say the applicator flange to which the handling end of the applicator rod can be attached and the handle which the user holds in his hand.
Further it is important, that the handle has a diameter which resembles the common applicators without a torque limiter attached thereto, in order not to change the accustomed subjective feeling for the torque to which the torque limiter is preset by a different handle diameter. This may cause the users to lose confidence in the torque limiter.
If the torque limiter is positioned at the front end of the applicator i.e. for example between the applicator rod and the sensor, then due to the single use concept of the applicator just a mechanically simple, easily and inexpensively producible form can be considered. This could be for example a concept where the front end of the applicator and the part which directly carries the sensor interact as a mechanical sliding clutch so that one of the parts has a non-round exterior shape, e.g. an ellipse or a polygonal shape, and is surrounded by another part which has an analog interior shape.
If one of the components, especially the surrounding component, shows a relatively high material-elasticity, and if there is enough play between the inner and outer outlines, the inner part will slip through relative to the exterior part at a maximum applicable torque, which creates the maximum torque limitation. After th

Affiliated with

Also associated with

Rating

Applicator for pulsoxymetric sensor with torque limiter does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Applicator for pulsoxymetric sensor with torque limiter, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Applicator for pulsoxymetric sensor with torque limiter will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2539927