VENTILATION OF MEDICAL GASES

Abstract: A downdraft system is used for withdrawing and collecting medical gases, fumes, mists and particulates from the vicinity of a patient's face. Two intakes (16) are located on respective sides of the patient's face, at the cheeks. The intakes extend from temple to chin. They are connected through a ducting system (28-46) to a source of vacuum (48) for collecting the medical gases. The ducting system is configured to allow the adjustment of the intake positions. The intakes create a flow of air across the patient's face from above the nose to below the mouth so that gases leaking during administration of gases or exhaled by the patient, and fumes, mists or low velocity particulates generated, for example, in orthodontic procedures, are captured in the flow across the patient's face into the intakes. This leaves the patient's mouth and nose fully exposed and unobstructed by the gas evacuation apparatus so that the administration of gases, dental treatments and any other procedures requiring access to the mouth and nose area may be carried out.

Description: VENTILATION QF MEPICAL GASES FIEIP OF THE INVENTION The present invention is concerned with the collection of gases, especially medical gases, and airborne contaminants, for example fumes, mists and particulates, from the vicinity of the face of a patient. BACKGROUND In the application of anesthetic or analgesic gases by means of a gas delivery mask to medical and dental patients, gas often escapes into the area around the patient's face and eventually dissipates into a wider area, exposing those in the vicinity to the gas. Studies of this problem are reported in Sass-Kortsak et al.: "Exposure of Hospital Operating Room Personnel to Potentially Harmful Environmental Agents". Am. Ind. Hyg. Assoc. J., Vol. 53, No. 3, March 1992, pp. 203-209 and Tran et al.: "Evaluation of Waste Anesthetic Gases Monitoring Strategies, and Correlations Between Nitrous Oxide Levels and Health Symptoms". Am. Ind. Hyg. Assoc. J., Vol. 55, No. 1 , January 1994, pp. 37-41. One aspect of the invention relates to a method of evacuating gases and airborne contaminants from adjacent the face of a patient by creating an area of low pressure adjacent the patient's face and collecting gases flowing into the low pressure area. Another aspect of the invention relates to a medical gas evacuation apparatus for withdrawing gas from adjacent the face of a patient, the apparatus comprising gas intake means, support means for supporting the intake means adjacent the patient's face and suction means for drawing air and the medical gas into the inlet means and collecting the gas so drawn in. A method and an apparatus of the above type are disclosed in US patent 4,895,172, issued 23 January 1990 to Erik A. Lindkvist. This patent discloses a hollow cup that is set over a patient's chin and attached to the patient's head with a harness. Gases are drawn into openings in the front of the cup and thence to a vacuum source. Various other proposals have been made for dealing with this problem. These include auxiliary ventilation, as reported in Mickelsen et al.: "Auxiliary Ventilation for the Control of Nitrous Oxide in a Dental Clinic". Appl. Occp. Environ. Hyg., Vol 8, No. 6, June 1993, pp. 564-570. That study concluded that air flow rates sufficiently high to cause noise problems or a hood relatively close to the patient would be required for adequate control. Neither high noise levels nor a hood close to a patient's face is acceptable in many, if not most, dental and surgical applications. For example, in dentistry full access to the patient's mouth, without obstruction, is required. Other proposals are found in the following: United States patent 5,195,512 issued March 23, 1993, which discloses a suction tube supported in position above the patient's face; United States patent 4,807,617 issued February 28, 1989, which discloses a mask with a scavenging cup on its outer side; United States patent 3,877,691 issued April 15, 1975, which discloses a hollow hood or shield, perforated on one side and connected to a suction line; None of these devices is fully satisfactory. Hoods, shields and masks cover the face at least partially and are not useful in many applications. Suction devices spaced from the face are not exceptionally effective as reported by Mickelsen et al. (supra). A suction arrangement at the chin, as proposed in Lindkvist will not adequately draw in gases leaking from a mask around the nose, because the mask, the hands of a dentist or other obstructions are in the flow path. A chin cup also obstructs access to the mouth for dental and the like treatments. The present invention is concerned with a method and an apparatus for the effective capturing of these medical gases, and fumes, mists and particulates generated during dental and surgical procedures, while allowing substantially full access to the patient's face, including mouth and nose, for dental treatment, the administration of the gases or substantially any other purpose desired. SUMMARY According to the present invention there is provided a method of the type described above that is characterised in that low pressure areas are produced on opposite sides of the patient's face, beside the patient's cheeks. The low pressure areas are created by placing gas intakes bilaterally at the cheeks of the patient. This withdraws gas across the face and down into the inlets. Gases escaping from any area around a mask or nose cup or from a patient's mouth or nose during exhalation will be captured. The bilateral arrangement ensures that there are no dead zones around the mouth and nose area. The intakes, being at the cheeks, are well clear of the mouth and nose, so that gases may be administered in the usual ways and there will be minimal interference with such things as dental procedures. According to another aspect of the present invention there is provided an evacuation apparatus as described above , characterised in that: the gas intake means comprise two gas intakes; and the support means support the respective gas intakes on respective opposite sides of the patient's face, at the cheeks. The gas collected will include escaping medical gases as well as ambient air and any airborne contaminants from a location as close as possible to the source from which they are emitted. Medical gases generally are denser than air and will naturally sink in air. The apparatus thus augments the natural flow of these gases when the patient is in the supine position normally adopted for dental and surgical procedures. This contrasts with the withdrawal of gases against their natural flow and from some considerable spacing with overhead suction devices. The intakes are preferably flat, flaring ducts with open inner sides facing the patient's cheeks, and open front ends facing forwards. The open front ends preferably extend from the temple to the chin of the patient. It has been found that a front end width of 1 Vi inches (3.8 cm) will draw a sufficient volume of air at a velocity low enough to minimize the noise produced. The intakes may be mounted for adjustment relative to the patient. This may be done by mounting the intakes for rotation on telescopic suction ducts that allow adjustment of the intakes laterally, towards and away from one another. It is also preferred that the intakes are made from a relatively soft material that is at least slightly deformable to allow the intakes to be shaped to conform closely with the patient's face. This reduces the intake of air from locations other than along the patient's cheeks and thus improves efficiency. ln some applications, the apparatus may be installed permanently, for example on a dental chair. In other applications, the apparatus may be portable. BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings, which illustrate an exemplary embodiment of the present invention: Figure 1 is a front view of an apparatus according to the present invention; Figure 2 is a back view of the apparatus; Figure 3 is a top view of the apparatus; Figure 4 is a side view of the apparatus; and Figure 5 is an inside view of an intake. DETAILED DESCRIPTION The terms "front", "back", "top" and "side" are all used relative to a patient's head since the absolute orientation of the apparatus is dependent on the actual orientation of the patient at the time of use. Referring to the accompanying drawings, there is illustrated a gas evacuation apparatus 10 shown associated with the head rest of an existing dental chair 12, partially illustrated in broken lines. Figures 1 and 3 of the drawings also show a patient's head 14 associated with the apparatus. The evacuation apparatus includes two inlet intakes 16 that are, in use, positioned on opposite sides of the patient's head, adjacent the cheeks. Each intake has an open inner side 18 confronting the adjacent cheek of the wearer, an open front end 20 and an opposite exhaust end 22. Each intake is generally rectangular in cross section and flares in height from the exhaust end 22 to the front end 20. The intakes are made from a resilient rubber material that is somewhat deformable so that its shape can be altered to match that of the patient's face. The exhaust end 22 of each intake is connected to a duct 24. The duct has a transition section 26 with a rectangular section front end 28 connected to the exhaust end 22 of the intake and a circular cross section back end 30. The duct has a rear cylindrical section 32 that slides telescopicallγ, front to back, in an adjustment sleeve 34 so that the fore and aft position of the intake can be adjusted. The cylindrical section 32 also rotates in the sleeve 34 so that the intake can be arranged parallel to the adjacent cheek of a patient. The adjustment sleeve 34 is connected to an elbow 36 which in turn is connected to an upright duct section 38. The connections of the adjustment sleeve 34 to the intake and the elbow are effected by rubber seals that allow the lateral adjustment of the intake against the face of a patient. The two duct sections 38 connect to inlets at the opposite ends of a lateral manifold 40. The manifold has a center outlet 44 connected to an exhaust duct 46 leading to a vacuum source 48 that creates a low pressure in the complete evacuation system, thus creating low pressure zones in the intakes, at the patient's cheeks. In use, the intakes are located on opposite sides of the patient's head, at the cheeks. The intakes are sufficiently wide that the low pressure area in them will create a flow of air across the patient's face from above the nose to the chin and following the contours of the face. Medical gases escaping from a nose cup, a face mask or exhaled by the patient, fumes, mists and particulates will thus be drawn across the patient's face and into the intakes, which are positioned to take advantage of their natural downward flow. The open inner side of the intake effectively uses the patient's face itself as the inner wall of the intake so as to provide a very large intake area and to minimize the opportunity for gas to escape along the patient's face. With the use of this apparatus, the patient's face is minimally obstructed so that the mouth and nose are accessible for the application of gas in a conventional way or for such other procedures as dental treatment. It has been found that the apparatus is also useful in evacuating the mists, fumes and low velocity particulates generated in surgical and dental procedures. While one embodiment of the present invention has been described in the foregoing, it is to be understood that other embodiments are possible within the scope of the invention. For example, the illustrated embodiment is shown as attached to a chair such as used in a dental clinic. In other applications, for example in operating theaters, other physical arrangements of the evacuation ducting may be employed. Both permanent and portable installations are possible. The invention is therefore not to be considered limited to the exemplary embodiment described above, but only by the scope of the appended claims.

Claims: CLAIMS 1. A method of evacuating gases and airborne contaminants from adjacent the face of a patient, said method comprising creating an area of low pressure adjacent the patient's face and collecting gases flowing into the low pressure area, characterised in that low pressure areas are produced on opposite sides of the patient's face, beside the patient's cheeks. 2. A method according to Claim 1 comprising creating the low pressure areas by placing gas intakes on respective opposite sides of the patient's head, and applying a suction to said intakes. 3. A method according to Claim 1 or 2 wherein the low pressure areas extend from temple to chin on the patient's face. 4. A medical gas evacuation apparatus for withdrawing gas from adjacent the face of a patient, said apparatus comprising gas intake means, support means for supporting the intake means adjacent the patient's face and suction means for drawing air and the medical gas into the inlet means and collecting the gas so drawn in, characterised in that: the gas intake means comprise two gas intakes; the support means support the respective gas intakes on respective opposite sides of the patient's face, at the cheeks. 5. Apparatus according to Claim 4 wherein each gas intake means comprises an intake with an open end and an open side and the suction means comprise a duct secured to an exhaust end of the intake, opposite the open end. 6. Apparatus according to Claim 4 or 5 wherein the support means comprise means mounting the intake for selective movement with respect to the patient's face. 7. Apparatus according to Claim 6 wherein the support means comprise means mounting the intakes for movement laterally of the patient's face. 8. Apparatus according to Claim 6 or 7 wherein the support means comprise means mounting each intake for rotation of the intake . 9. Apparatus according to Claim 6, 7 or 8 wherein the support means comprise means for moving each intake fore and aft beside the patient's head. 10. Apparatus according to any one of Claims 5 to 9 wherein each intake is generally rectangular in cross section and flares in height from the exhaust end to the open end. 1 1. Apparatus according to any one of Claims 5 to 10 wherein each intake is made from a deformable material.

Inventors: KORCZYNSKI RITA, NEPON MARK, SABESKY IVAN, KORCZYNSKI, RITA, NEPON, MARK, SABESKY, IVAN
Applicants: KORCZYNSKI RITA, NEPON MARK, SABESKY IVAN, KORCZYNSKI, RITA, NEPON, MARK, SABESKY, IVAN
Application year: 1995
Main classification: A61M16
IPC codes: A61M16