Title of Invention

"A MINIATURE ONE-WAY BREATHING VALVE ASSEMBLY FOR LABORATORY ANIMALS"

Abstract

This invention relates to a miniature one way breathing valve assembly for laboratory animals comprising an open ended tubular breathing chamber (2) with openings (3) and (4) at opposite ends and having a tracheal tube hole (5), a tracheal tube (1) having one end inserted in said tracheal tube hole (5) of breathing chamber (2), a pair of one way breathing valves (6) and (7) separately attached to a pair of rubber seats (8) provided on either sides of said tracheal tube hole (5) inside said breathing chamber (2), a pair of sample ports (9) and (10) provided outside on either side of the said breathing chamber (2) for simultaneous sampling of inhaled and exhaled-breath separately.

Full Text

Field of the invention: This invention relates to a device, which can be connected to the trachea of laboratory animals, particularly small laboratory animals for supporting breathing and or for carrying out physiological/pharmacological experiments. Prior Art: In many physiological, pharmacological and toxicokinatic investigations, direct repetitive sampling of breath and monitoring of respiratory function is mandatory during exposure to test gases/volatile chemicals. These studies require continuous sampling of inhaled and exhaled breath separately to determine alveolar concentration and elimination of test gases/volatile chemicals in order to monitor and control the inhaled exposures. For carrying out such studies, a one way-breathing valve is a must for sampling of inhaled and exhaled breath separately. Such breathing devices are commercially available for carrying out respiratory function studies in human subjects exposed to test gases/volatile chemicals. However, studies in humans are not always possible due to ethical considerations as one cannot administer high levels of solvents or evaluate the kinetics of potentially toxic or carcinogenic chemicals. Alternatively, some large animals like monkeys and dogs have been used in such studies by conditioning them to breathe through the non-breathing valves similar to those utilized for humans. However, such studies are very much limited in small laboratory animals like mice or rats due to non-availability of suitable breathing devices. Previous studies regarding the characterisation of uptake and elimination of test gases/organic solvents in mice and rats necessitated sacrifice of a large number of animals at each point of time or restraining them in the dynamic exposure apparatus. Although these methods are useful for determination of study state uptake of solvents, technical limitations apparently do not allow accurate determination of uptake and elimination profile. Therefore, there is a definite need for development of a suitable device for direct, repetitive sampling of inhaled and exhaled breath separately during exposure of small animals to test gases/ volatile chemicals. The one-way breathing valve assembly of the present invention overcomes the disadvantages of the prior art. Objects of the invention: The main object of the invention is to provide a miniature one-way breathing valve assembly for laboratory animals, particularly small laboratory animals like frogs etc. Another object of the invention is to provide a miniature one-way breathing valve assembly for laboratory animals, which is capable of performing repetitive sampling of breath and monitoring respiratory function is small laboratory animals such as fogs etc. Still another object of the invention is to provide a miniature one-way breathing valve assembly, which can carefully monitor and control key physiological functions during exposure to test gases/volatile chemicals. Yet another object of the invention is to provide a miniature one-way breathing valve assembly, which can administer desired doses of test gases/volatile chemicals accurately to the laboratory animals. Yet further object of the invention is to provide a miniature one-way breathing valve assembly, which can sample the inhaled and exhaled breath of the laboratory animals separately to determine alveolar concentrations, systemic uptake and elimination of gases accurately. Still further object of the invention is to provide a miniature one-way breathing valve assembly, which has a very minimal dead space to reduce burden on the respiration of the experimental animals. Yet further object of the invention is to provide a miniature one-way breathing valve assembly device, which is extremely simpler, cheap and very easy to use. STATEMENT OF INVENTION According to this invention there is provided a miniature one way breathing valve assembly for laboratory animals comprising: an open ended tubular breathing chamber (2) with openings (3) and (4) at opposite ends and having a tracheal tube hole (5), a tracheal tube (1) having one end inserted in said tracheal tube hole (5) of breathing chamber (2), a pair of one way breathing valves (6) and (7) separately attached to a pair of rubber seats (8) provided on either sides of said tracheal tube hole (5) inside said breathing chamber (2), a pair of sample ports (9) and (10) provided outside on either side of the said breathing chamber (2) for simultaneous sampling of inhaled and exhaled breath separately. DESCRIPTION OF INVENTION WITH REFERENCE TO ACCOMPANYING DRAWINGS Figure 1 shows a detailed view of the one-way breathing valve assembly. Figure.2:shows the breathing valve assembly of the present invention connected to trachea of the animal. Figure.3:shows Blood p02, pC02, Sa02 levels and respiratory rate before and. after fixing the breathing valve as well as during hypoxic exposure Figure.4:shows concentration 02 In inspiratory and expiratory air samples ,before and after hypoxic exposure. Referring to Figure 1, the breathing valve assembly of the present invention comprises of a 2 cm long tracheal tube (1) with an outer diameter of 2 mm and inner diameter of 1.7 mm. It is made up of a rigid tissue compatible material, which can be easily placed inside the tracheg of the anesthetised animals. The breathing chamber (2) is made up of an about 5 cm long rigid medical grade polythene tube with an internal diameter of 5.0 mm and the outer diameter of 7 mm. The chamber is open from both the ends (3 & 4) and has a hole (5) at the middle through which the tracheal tube is inserted. The opening at one end (3) of the chamber serves as inlet for the administration of test gases into the lung through the tracheal tube; whereas the exhaled air is eliminated outside through opening (4) on the opposite end. A pair of breathing valve made up of thin latex rubber flaps (6 & 7) having negligible resistance to the air passage are attached to rubber seats (8) on either side of the tracheal tube hole inside the chamber (5). The valves are placed in such a way that the inhaled air is allowed to pass through one side opening (3) and exhaled air is directed through the opening (4) on the opposite side of the breathing chamber. A pair of sample ports (9 & 10) made up of thin Teflon tube (2.0 mm OD) is fixed outside on either side of the breathing chamber immediately adjacent to the one way breathing valve for continuous sampling of breaths. Figure 2, shows the placement of breathing valve assembly in the trachea (11) of the anesthetised animal. The tracheal tube is inserted directly into the trachea of anesthetised animals and fixed firmly by placing a ligature (12) at the point of insertion. The one,way breathing valves are positioned in such a way that the negative pressure generated by inhalation of the animal pulls the inhalation valve open and the exhalation valve is closed against its seat. Upon exhalation, positive pressure generated within the device pushes the exhalation valve open and the inhalation valve is closed, thereby establishing separate and distinct airways for the inhaled and exhaled breath. The inhalation and exhalation valves offer very minimal resistance to air flow, as they are made up of thin flexible latex rubber and attached only at the bottom of the seat. Inhalation and exhalation sampling ports are located immediately adjacent to the breathing valve for continuous sampling of breath. Major advantage of this device is presence of nagligible dead space (0.1 ml), which does not put much burden on the respiration of the animal. Referring to Figure 3 & 4, the performance of the device was evaluated in male rats exposed to hypoxic gas mixture (10% 02 & 90% N2) through the breathing device. The inhaled and exhaled breath samples were collected repeatedly for analysis of gases. Blood pO2, pC02 and SaO2 were also monitored by collecting arterial blood samples before and during hypoxic exposure under anaerobic conditions. The results from the study, as shown in these figures clearly indicate that the miniature valve assembly of the present invention could be used for delivering hypoxic gas mixtures to small laboratory animals for creating alveolar hypoxia. The present embodiment of the invention, which has been set forth above, was for the purpose of illustration and is not intended to limit the scope of the invention. It is to be understood that various changes, adaptations and modifications can be made in the invention described above by those skilled in the art without departing from the scope of the invention, which has been defined by following claims FjeBd of the invention: This invention relates to a device, which can be connected to the trachea of laboratory animals, particularly small laboratory animals for supporting breathing and or for carrying out physiological/pharmacological experiments. Prior Art: In many physiological, pharmacological and toxicokinatic investigations, direct repetitive sampling of breath and monitoring of respiratory function is mandatory during exposure to test gases/volatile chemicals. These studies require continuous sampling of inhaled and exhaled breath separately to determine alveolar concentration and elimination of test gases/volatile chemicals in order to monitor and control the inhaled exposures. For carrying out such studies, a one way-breathing valve is a must for sampling of inhaled and exhaled breath separately. Such breathing devices are commercially available for carrying out respiratory function studies in human subjects exposed to test gases/volatile chemicals. However, studies in humans are not always possible due to ethical considerations as one cannot administer high levels of solvents or evaluate the kinetics of potentially toxic or carcinogenic chemicals. Alternatively, some large animals like monkeys and dogs have been used in such studies by conditioning them to breathe through the non-breathing valves similar to those utilized for humans. However, such studies are very much limited in small laboratory animals like mice or rats due to non-availability of suitable breathing devices. Previous studies regarding the characterisation of uptake and elimination of test gases/organic solvents in mice and rats necessitated sacrifice of a large number of animals at each point of time or restraining them in the dynamic exposure apparatus. Although these methods are useful for determination of study state uptake of solvents, technical limitations apparently do not allow accurate determination of uptake and elimination profile. Therefore, there is a definite need for development of a suitable device for direct, repetitive sampling of inhaled and exhaled breath separately during exposure of small animals to test gases/ volatile chemicals. The one-way breathing valve assembly of the present invention overcomes the disadvantages of the prior art. Objects of the invention: The main object of the invention is to provide a miniature one-way breathing valve assembly for laboratory animals, particularly small laboratory animals like frogs etc. Another object of the invention is to provide a miniature one-way breathing valve assembly for laboratory animals, which is capable of performing repetitive sampling of breath and monitoring respiratory function in small laboratory animals such as fogs etc Still another object of the invention is to provide a miniature one-way breathing valve assembly, which can carefully monitor and control key physiological functions during exposure to test gases/volatile chemicals. Yet another object of the invention is to provide a miniature one-way breathing valve assembly, which can administer desired doses of test gases/volatile chemicals accurately to the laboratory animals. Yet further object of the invention is to provide a miniature one-way breathing valve assembly, which can sample the inhaled and exhaled breath of the laboratory animals separately to determine alveolar concentrations, systemic uptake and elimination of gases accurately. Still further object of the invention is to provide a miniature one-way breathing valve assembly, which has a very minimal dead space to reduce burden on the respiration of the experimental animals. Yet further object of the invention is to provide a miniature one-way breathing valve assembly device, which is extremely simpler, cheap and very easy to use. DETAILED DESCRIPTION OF INVENTION According to this invention there is provided a miniature one way breathing valve assembly for laboratory animals comprising : an open ended tubular breathing chamber (2) with openings (3) and (4) at opposite ends and having a tracheal tube hole (5), a trachea! tube (1) having one end inserted in said tracheal tube hole (5) of breathing chamber (2), a pair of one way breathing valves (6) and (7) separately attached to a pair of rubber seats (8) provided on either sides of said tracheal tube hole (5) inside said breathing chamber (2), a pair of sample ports (9) and (10) provided outside on either side of the said breathing chamber (2) for simultaneous sampling of inhaled and exhaled breath separately. DESCRIPTION OF INVENTION WITH REFERENCE TO ACCOMPANYING DRAWINGS Figure 1 shows a detailed view of the one-way breathing valve assembly. Figure.2:shows the breathing valve assembly of the present invention connected to trachea of the animal. Figure.3:shows Blood p02, pC02, Sa02 levels and respiratory rate before and. after fixing the breathing valve as well as during hypoxic exposure Figure.4:shows concentration 02 In inspiratory and expiratory air samples ,before and after hypoxic exposure. Referring to Figure 1, the breathing valve assembly of the present invention comprises of a 2 cm long tracheal tube (1) with an outer diameter of 2 mm and inner diameter of 1.7 mm. It is made up of a rigid tissue compatible material, which can be easily placed inside the tracheg of the anesthetised animals. The breathing chamber (2) is made up of an about 5 cm long rigid medical grade polythene tube with an internal diameter of 5.0 mm and the outer diameter of 7 mm. The chamber is open from both the ends (3 & 4) and has a hole (5) at the middle through which the tracheal tube is inserted. The opening at one end (3) of the chamber serves as inlet for the administration of test gases into the lung through the tracheal tube; whereas the exhaled air is eliminated outside through opening (4) on the opposite end. A pair of breathing valve made up of thin latex rubber flaps (6 & 7) having negligible resistance to the air passage are attached to rubber seats (8) on either side of the tracheal tube hole inside the chamber (5). The valves are placed in such a way that the inhaled air is allowed to pass through one side opening (3) and exhaled air is directed through the opening (4) on the opposite side of the breathing chamber. A pair of sample ports (9 & 10) made up of thin Teflon tube (2.0 mm OD) is fixed outside on either side of the breathing chamber immediately adjacent to the one way breathing valve for continuous sampling of breaths. Figure 2, shows the placement of breathing valve assembly in the trachea (11) of the anesthetised animal. The tracheal tube is inserted directly into the trachea of anesthetised animals and fixed firmly by placing a ligature (12) at the point of insertion. The one,way breathing valves are positioned in such a way that the negative pressure generated by inhalation of the animal pulls the inhalation valve open and the exhalation valve is closed against its seat. Upon exhalation, positive pressure generated within the device pushes the exhalation valve open and the inhalation valve is closed, thereby establishing separate and distinct airways for the inhaled and exhaled breath. The inhalation and exhalation valves offer very minimal resistance to air flow, as they are made up of thin flexible latex rubber and attached only at the bottom of the seat. Inhalation and exhalation sampling ports are located immediately adjacent to the breathing valve for continuous sampling of breath. Major advantage of this device is presence of nagligible dead space (0.1 ml), which does not put much burden on the respiration of the animal. Referring to Figure 3 & 4, the performance of the device was evaluated in male rats exposed to hypoxic gas mixture (10% 02 & 90% N2) through the breathing device. The inhaled and exhaled breath samples were collected repeatedly for analysis of gases. Blood pO2, pC02 and SaO2 were also monitored by collecting arterial blood samples before and during hypoxic exposure under anaerobic conditions. The results from the study, as shown in these figures clearly indicate that the miniature valve assembly of the present invention could be used for delivering hypoxic gas mixtures to small laboratory animals for creating alveolar hypoxia. The present embodiment of the invention, which has been set forth above, was for the purpose of illustration and is not intended to limit the scope of the invention. It is to be understood that various changes, adaptations and modifications can be made in the invention described above by those skilled in the art without departing from the scope of the invention, which has been defined by following claims I CLAIM: 1. A miniature one way breathing valve assembly for laboratory animals comprising: an open ended tubular breathing chamber (2) with openings (3) and (4) at opposite ends and having a tracheal tube hole (5), a tracheal tube (1) having one end inserted in said tracheal tube hole (5) of breathing chamber (2), a pair of one way breathing valves (6) and (7) separately attached to a pair of rubber seats (8) provided on either sides of said tracheal tube hole (5) inside said breathing chamber (2), a pair of sample ports (9) and (10) provided outside on either side of the said breathing chamber (2) for simultaneous sampling of inhaled and exhaled breath separately. 2. A miniature one way breathing valve assembly for laboratory animals as claimed in claim 1 wherein said tracheal tube (1) is made of a rigid tissue compatible material. 3. A miniature one way breathing valve assembly for laboratory animals as claimed in claim 1 wherein said breathing chamber (2) is made of medical grade polythene tube. 4. A miniature one way breathing valve assembly for laboratory animals as claimed in claim 1 wherein said opening (3) at one end of the said breathing chamber (2) serves as an inlet for the administration of test gases into the lung of a laboratory animal through the said tracheal tube (1) and whereas the exhaled air is sent outside through the said opening (4) on the opposite end of the said breathing chamber (2). 5. A miniature one way breathing valve assembly for laboratory animals as claimed in claim 1 wherein said one-way breathing valves (6) and (7) are made of thin flexible latex rubber flaps 6. A miniature one way breathing valve assembly for laboratory animals as claimed in claim I wherein said pair of sample ports (9) and (10) are made up of thin Teflon tube 7. A miniature one way breathing valve assembly for laboratory animals substantially as described and illustrated herein.

Documents:

502-DEL-2004-Abstract (24.OCT.2007).pdf

502-DEL-2004-Abstract-(11-09-2008).pdf

502-DEL-2004-Abstract-(24-06-2008).pdf

502-del-2004-abstract.pdf

502-del-2004-claims-11-09-2008.pdf

502-del-2004-claims-24-06-2008.pdf

502-del-2004-claims.pdf

502-DEL-2004-Correspondence-Others(24.OCT.2007).pdf

502-DEL-2004-Correspondence-Others-(11-09-2008).pdf

502-DEL-2004-Correspondence-Others-(24-06-2008).pdf

502-del-2004-correspondence-po.pdf

502-del-2004-correspondence.pdf

502-DEL-2004-Description (Complete)-(24-06-2008.pdf

502-DEL-2004-Description (Complete)-(24-10-2007).pdf

502-DEL-2004-Description (Complete)-11-09-2008.pdf

502-del-2004-description.pdf

502-DEL-2004-Drawings-(18-03-2004).pdf

502-DEL-2004-Drawings-(24-06-2008).pdf

502-del-2004-drawings.pdf

502-DEL-2004-Form-2-(11-09-2008).pdf

502-DEL-2004-Form-2-(18-03-2004).pdf

502-DEL-2004-Form-2-(24-06-2008).pdf

502-DEL-2004-Form-26-(24-06-2008).pdf

502-DEL-2004-Form-3-(24-10-2007).pdf

502-del-2004-form1.pdf

502-del-2004-form2.pdf

502-DEL-2004-GPA-(11-09-2008).pdf

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