GB2328512A

GB2328512A - Monitoring respiration while simultaneously delivering oxygen to a person

Info

Publication number: GB2328512A
Application number: GB9815469A
Authority: GB
Inventors: Graham Cameron Grant
Original assignee: Individual
Current assignee: Individual
Priority date: 1997-07-22
Filing date: 1998-07-17
Publication date: 1999-02-24
Also published as: GB9815469D0

Abstract

To monitor respiration whilst simultaneously delivering oxygen to a person, oxygen from a pressurised source (10) is delivered directly into one nasal passage (14) of the person by way of a first tube (13) and gas that is exhaled during normal rhythmic breathing by the person is sampled by way of a second tube (15) that is projected directly into the other nasal passage (16). Successive samples of the exhaled gas are conveyed to an analyser (19, 20) by way of the second tube (15), and respiration is monitored by reference to cyclic exhalation of the gas through the second tube (15) and into the analyser (19, 20).

Description

METHOD OF AND APPARATUS FOR MONITORING RESPIRATION WHILST DELIVERING OXYGEN TO A PATIENT FIELD OF THE INVENTION This invention relates to a method of monitoring respiration whilst simultaneously delivering oxygen to a person, and to an apparatus for use in implementing the method.

BACKGROUND OF THE INVENTION It is desirable, if not necessary, in various medical procedures that respiration of a patient be monitored during the time that oxygen is being administered to the patient. This is required, for example, during surgical procedures that require intravenous sedation anaesthesia or neuroleptanalgesia. It is also required in some intensive care situations.

Simultaneous oxygen delivery and respiration monitoring may be achieved when a facemask is used as a vehicle for delivering the oxygen, typically by inserting a sampling tube into one side of the mask and by sampling expired carbon dioxide that is exhaled through the sampling tube. However, there are circumstances in which a facemask cannot conveniently be used, for example when performing procedures such a gastroscopy and during the performance of surgical procedures on a patient's head, neck or face under combined intravenous sedation anaesthesia and local analgesia. In these procedures the facemask and associated gas delivery/sampling tubing may impede surgery or, in any event, be found obtrusive by surgeons.

Alternative oxygen delivering systems that are not so obtrusive are available, for example, nasal catheters and nasal prongs. However, these systems as they currently exist do not permit respiration monitoring of expired gases.

SUMMARY OF THE INVENTION The present invention obviates the above mentioned difficulties by providing a method of and apparatus for delivering oxygen to a patient in an unobtrusive way whilst, at the same time, providing for respiration monitoring.

Broadly defined, the method of the present invention comprises delivering oxygen from a pressurised source directly into one only of the nasal passages of a person by way of a first tube. Also, exhaled gas is sampled by (ie, breathed into) a second tube that is projected directly into the other nasal passage of the person. Successive samples of the exhaled gas are conveyed to an analyser by way of the second tube, and respiration is monitored by reference to the cyclic exhalation of the gas through the second tube and into the analyser.

The invention as defined in the preceding paragraph has been developed from an understanding gained by the inventor, that oxygen that is delivered to one of the nasal passages of a person does not materially influence the flow of exhaled gas through the other nasal passage. As a consequence, the exhaled gas that passes through the second tube may be analysed to provide a sufficient indication as to the respiration of the person during administration of the oxygen.

The apparatus that has been developed in accordance with the present invention may be defined as providing first and second tubes which have end portions that are shaped and sized to project into respective nasal passages of a person. The first tube is arranged in use to be connected to a source of pressurised oxygen and the second tube is arranged in use to be connected to apparatus that is adapted to analyse gas for the presence of exhaled respiratory gas and to provide indication of the presence of exhaled respiratory gas.

PREFERRED FEATURES OF THE INVENTION The two (first and second) tubes preferably are connected together side-by-side over a portion of their lengths, so that they may conveniently be positioned along the mid-line of a person's face and be held in place on the person's nose. This results in a compact, minimally obtrusive arrangement. At least one support pad preferably is connected to the tubes so as to permit convenient positioning of the two tubes on the person's face.

The analyser preferably is one which detects for the presence of carbon dioxide and which provides a display that is representative of the presence of carbon dioxide.

The invention will be more fully understood from the following description of a preferred embodiment of an apparatus that may be employed in the context of the invention. The description is provided with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings Figure 1 shows a diagrammatic representation of an implementation of the invention, Figure 2 shows an apparatus that may be employed in implementation of the invention, Figure 3 shows the apparatus of Figure 2 when secured to a patient in a first manner, and Figure 4 shows the apparatus of Figure 2 when secured to the patient in a second manner.

DETAILED DESCRIPTION OF THE INVENTION As shown in Figure 1, the complete system that embodies the invention comprises a source of pressure regulated oxygen 10, an oxygen delivery line 11, a first coupling 12 and a first tube 13 which is arranged to deliver the oxygen to one nasal passage 14 of a patient.

The system further comprises a second tube 15 which is arranged to receive exhaled gases from the other nasal passage 16 of the patient during normal rhythmic breathing, a second coupling 17, a sample gas delivery line 18, a carbon dioxide analyser 19 and a display monitor 20 which is associated with the analyser 19. The analyser/monitor 19, 20 may comprise a conventional form of infra-red CO2 monitoring apparatus, for example of the type that is manufactured by Datex Engstrom of Finland and sold as a Datex Model AS/3 analyser unit.

As indicated previously, the present invention has been developed from the inventor's recognition that oxygen may be supplied to one (first) nasal passage only, to be inhaled by the patient, and that the concentration of exhaled gases when taken from the other (second) nasal passage will not for practical purposes be affected significantly by oxygen that is delivered to the first nasal passage. This recognition has enabled an approach to be taken which is different from the past practice of delivering oxygen to both nasal passages for inhalation and then sampling gases that are exhaled from both nasal passages for respiration monitoring purposes.

The portion of the delivery/sampling system that is connected directly to the patient is shown in more detail in Figures 2 to 4. This portion comprises the first and second tubes 13 and 15.

Both of the tubes 13 and 15 are joined or connected together side-by-side along a major portion of their lengths and both of the tubes are fitted at one end with respective U-tube fittings 21. Each of the fittings 21 has one leg 22 which is arranged to project into a respective one of the nasal passages 14 and 16 of the patient, and the free end of each fitting is shaped and sized to minimise discomfort to the patient when located in place.

A support pad 23 is secured to both of the tubes 13 and 15 and is provided for resting on and/or for attachment to the patient's nose as shown in Figures 3 and 4. The tubing may be held in place by attaching it to the forehead of the patient, using a strip of medical adhesive tape 24 as shown in Figure 3, or the two tubes 13 and 15 may be divided and formed into a headband 25 and be secured to the patient in the manner shown in Figure 4.

Claims

1. A method of monitoring respiration of a person whilst delivering oxygen to the person, the method comprising the steps of: delivering the oxygen from a pressurised source directly into one only of the nasal passages of the person by way of a first tube, sampling exhaled gas from the person by way of a second tube, the second tube being projected directly into the other nasal passage of the person, conveying successive samples of the exhaled gas to an analyser by way of the second tube, and monitoring the respiration of the person by reference to cyclic exhalation of the gas through the second tube and into the analyser.

2. The method as claimed in claim 1 wherein the first and second tubes are located side-by-side over a portion of their length and are positioned to extend along the midline of the person's face.

3. A method as claimed in claim 1 or claim 2 wherein the exhaled gas is analysed for the presence of carbon dioxide and the analyser functions to provide a display that is representative of the presence of carbon dioxide in the exhaled gas.

4. The method of monitoring respiration of a person whilst delivering oxygen to the person, substantially as hereinbefore described with reference to the accompanying drawings.

5. An apparatus for use in monitoring respiration of a person and for simultaneously delivering oxygen to the person, the apparatus comprising first and second tubes which are arranged to be positioned to lie along the midline of the face of a person to whom the apparatus is in use fitted, each of the tubes being formed from a flexible, plastics material and having an end portion that is shaped and sized to project into a respective one of the nasal passages of the person, the first tube in use being connected to a source of pressurised oxygen, and the second tube in use being connected to an analyser that is arranged to analyse gas for the presence of exhaled respiratory gas and to provide indication of the presence of respiratory gas that is exhaled cyclically by the person to whom the apparatus is fitted.

6. The apparatus as claimed in claim 5 wherein the first and second tubes are connected side-by-side over a portion of their length, whereby the tubes may conveniently be positioned along the mid-line on the person's face and be held in place on the person's nose.

7. The apparatus as claimed in claim 5 or claim 6 wherein each of the tubes is fitted at one end with a U-tube which has one leg which is shaped and adapted to locate within a respective nasal passage of the person.

8. The apparatus as claimed in claim 6 or claim 7 wherein the two tubes are carried by a pad which is itself shaped and arranged to overfit the nose of the person to whom the apparatus is fitted.

9. The apparatus as claimed in any one of claims 5 to 8 wherein the first and second tubes are arranged in use to be held in place by taping them to the forehead of the person.

10. The apparatus as claimed in any one of claims 6 to 8 wherein the first and second tubes are divided over a further portion of their length and wherein the divided portions are formed into a headband which is arranged in use to encircle the head of the person to whom the apparatus is fitted.

11. The apparatus for monitoring respiration of a patient whilst simultaneously delivering oxygen to the person, substantially as shown in the accompanying drawings and substantially as hereinbefore described with reference thereto.