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Publication numberUS2225201 A
Publication typeGrant
Publication dateDec 17, 1940
Filing dateMay 26, 1938
Priority dateMay 31, 1937
Also published asDE758616C
Publication numberUS 2225201 A, US 2225201A, US-A-2225201, US2225201 A, US2225201A
InventorsWilhelm Anderson Emil Einar
Original AssigneeSvenska Aktiebolaget Gassaccum
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Apparatus for administering anesthesia
US 2225201 A
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Description  (OCR text may contain errors)

17, 1940- E. E. w. ANDERSON Filed May 26, 1938 43 is fl liiwlllil xxxx u 5Q 1" 55 VP/Izzy... 44 45 a6 25 27 a y i 55 34 E L 47 i K 55 5 55 45 E E Z 42 54 W Z- 7%, ENTER E. E. W. ANDERSON APPARATUS FOR ADMINISTERING ANESTHESIA Dec. 17, 1940..

Filed May 26, 1938 3 Sheets-Sheet 2 M ATTORNEY Dec. 17, 1940. w ANDERSON 2,225,201

APPARATUS FOR ADMINISTERING ANESTHESIA Filed May 26, 1938 5 Sheets-Sheet 3 W 1 [W VE TOR Patented Dec. 17, 1940 APPARATUS FOR ADMINISTEBING ANESTHESIA Emil Einar Wilhelm Anderson, Lidingo, Sweden,

assignor to Svenska Aktiebolaget Gassaccumulator, Stockholm, Sweden, a corporation of Sweden Application May 26, 1938, Serial No. 210,120 In Sweden May 31, 1937' 13 Claims. (Cl. 128-488) My invention relates to apparatus for administering a gaseous anesthetic, such as nitrous oxide, and especially to an apparatus particularly adapted for administering an anesthetic for the relief of labor pains. For relieving labor pains it is desirable to maintain a weak narcosis, or socalled analgesic state, without permitting the patient to reach the excitation state or the absolute narcotic state. In the analgesic state the sensation of pain is removed, whereas the senses and the organs of the body are otherwise practically unaffected by the anesthesia. Most important, there is practically no decrease in the functions of the muscles.

In order to produce a short analgesic state it is necessary to administer a limited quantity of anesthetic. Heretofore this has been done by a physician or trained nurse and consequently it requires the constant attendance of such a person. Inasmuch as labor may continue for several hours, or in extreme cases for several days, it has been necessary for the physician, or nurse, to remain in attendance for such lengths of time.

One of the objects of my invention is to provide an apparatus which may be adjusted by the physician so as to administer a predetermined quantity of anesthetic, but which apparatus is under the control of the patient to the extent that she may determine when the anesthetic is to be administered. Thus, at the beginning of each labor pain, the patient is able to obtain a limited and predetermined amount of anesthetic which is suflicient to relieve the pain, but which is insufllcient to produce an absolute narcotic state. Thereafter no more anesthetic may be obtained by the patient until a predetermined minimum period of time has elapsed.

A further object of my invention is to provide, in an apparatus of this type, means whereby the physician or nurse may administer, in an emergency, larger quantities of anesthetic.

Further objects and advantages of my invention will be apparent from they following description considered in connection with the accompany drawings, which-form a part of this anesthetic under pressure. Container i0 is provided with a valve II for controlling flow therefrom into a conduit l2 which is provided with a pressure gauge l3, Conduit l2 communicates with a pressure governor l4. Governor l4 consists of a casing 15 within which is mounted a diaphragm IS, the upper surface of which is subjected toatmospheric pressure through openings II in the cover of the casing. A spring I8 is mounted within the casing and is arranged to press against 'a bolt 19 carried by diaphragm l6. Bolt I9 engages an angular member 20 which is pivoted on a fulcrum 2! carried by the casing. Pivotally engaging member 20 is a valve stem 22 which is held in contact with member 20 by a passage 25 to which conduit I2 is connected. A

plate spring 26 is stressed between the casing and one end of angular member 20. Casing I5 is provided with an outlet opening 21 which is connected to a conduit 28.

The wall of casing I5 is provided with a bypass channel 29 which communicates with the inlet opening 25 ahead of nipple 24. A valve 30 is arranged to control flow between passage 29 and a chamber 3| to which is connected a conduit 32. Valve 30 is mounted on a stem 33 which extends outside of the casing and is provided with a button 34. A spring 35 tends to hold valve 30 in closed position.

Conduit 28 communicates with an throttle valve of suitable type. valve includes-a needle 31 formed with screw threads which engage similar threads in the casing and which may be adjusted with relation to a valve seat 38 so as to control flow through the valve.

A conduit 39 connects the outlet side of valve 36 with a valve chamber 40 formed in a casing 4|. Conduit 32 also communicates with chamber 40. Mounted within the casing is a diaphragm 42, one side of which is subjected to atmospheric pressure through an opening 43 formed in the cover 44 of the casing. Rigidly connected to the center of the diaphragm by means of an arm 45 is a member 46 which is pivoted at 41 to the casing. Member 46 carries a valve 48 disposed in valve chamber 40 and a valve 49 arranged .to control communication between the interior of diaphragm chamber 50 and a chamber 5|. Member 46 is made of magnetic maadjustable As shown, this 3 terial and its end opposite from valves 48 and 49 velocity of flow of gas therethrough.

3 and with the lower end oimember 4 in contact with the pole 53 oi themagnet. ,Whengasis introduced through conduit II and valve 48 to is arranged to move betwee'nthe poles 5i and I! of a permanent magnet H.

A spring-loaded valve SI regulates communication between chamber II and a space II which is connected by means oi'a flexible tube 51 with an inhalation mask II. [A spring-loaded valve SI regulates communication between space I and the atmosphere. The loading of valve 5! with respect tothat of valve Ills such that valve- 55 opens under the influence oie smaller pres- The above described apparatus operates as follows: i a a Gas under pressure is supplied from container ll through valve Ii to conduit l2 and to the pressure regulator II. The construction of this regulator is such that it maintains a constant pressure within the casing ii. If the pressure within :the casing tends to rise, it. moves the diaphragm upwardly against the force of spring ll and against the .iorce of atmospheric pressure. This causes the angular member III to.

pivot in a counterclockwise direction about iul-i crum 2i which forces valve stem 22 to theright against the force of springs 23 and 26, thus restricting the opening through nipple 2| and hence reducing flow of gas into the chamber. A

drop in pressure within the chamber causes the diaphragm tomo've infthe opposite direction and thus increases the opening. The pressure regulator is adjusted toamaintain a desired pressure, for instance,,in the neighborhood of 5 mmrof water. I g

The gas under-this pressure leaves the regulator through conduit and passes through throttle conduit ll tohthe valve chamber III, thus byvalve 38, which maybeadiusted to regulate the When the apparatus is first started,latmos.- pheric pressure acting on. diaphragm holds it in a position opposite to that shown in Fig. 1; that is, with valve 0 opened and valve 4! closed the diaphragm chamber ".fliis gas flows into bulb and, as thepressure increases,causes the bulbto e pand until it strikes the plates I and 62.

Inasmuchas the position oi. the latter plate i may be adjusted by means of a set screw 88, the

volume of gas which the bulb is able to accommodate maybe regulated. After the bulb has i been fully e panded against the plates, the introduction of further gas causes the pressure in the diaphragm chamber to increase and henceto exert a force against the diaphragm tending to,

move it to the left, as viewed in Fig. i, which in turn tends to pivot member 48 in acounterclockwiseldirection. This is resistedby the attraction of the pole II of the magnet for the member ll and when the pressure increases sumciently to overcome this attraction the member I is? suddenly pivoted to the position shown in Fig. 1, that is with valve 48 closed and valve 4! open and member I in contact with the pole" oi the magnet. The pressure within the diaphragm chamber In is that determined by the pressure regulator ll, for instance 5mm. of water. 1 This pressure consequently tends. :to open valve il.

passes through the valve.

However, the loading oi this valve is such that a higheripressure. oi" for instance 10 mm. of water is required to open it. Consequently, no gas However. should the patient desire to be supplied with anesthetic she places themaskrllover her mouth and nose and inhales.= This reduces the pressure within the space llsuiilciently so that valve II is opened and thus permits the anesthetic to flow through the space II, tube 51 and mask I! to the patient.

The patient is able to inhale anesthetic until suincient. gas. has been removed from the diaphragm chamber II and thebulb II to reduce the pressure in the diaphragm chamber slightly below atmospheric whereupon atmospheric pressure 1 acting on the left side of the diaphragm moves it and the member I to a position in which valve 40 is closedand valve 48 is open. Thereafter, ii.

the patient continues to inhale through the mask II, the valve II is openedand she is supplied with atmospheric air.

The patient is not able to obtainiurther anesthetic immediately. butmustwait until the diaphragm chamber "and bulb I. has been filled again. The time required for. filling is deter? mined by the now through the throttle valve 36, which hencemay be setby the physician so as to determine a the minimum time between periods -"when anesthetic is available; However, the patient herself controls when. :aiter the minimum time has. expired, the next period of supply is to occur. Thephysician is also able to regulate the quantity of anesthetic which the patient receives each time by adjusting the setscrew 63 which regulates the volume of bulb 6| when fully expanded.

In .theevent that it becomes necessary to administer. large quantities of anestheticas in an emergency, this may be done by the physician ornursedepressing the button :34 which opens valve It and permits gas to flow directly from the passing the pressure regulator 14 and the throttle valve 36 and hence supplying gas continuously to the valve chamber 40..

In therembodiment shown in Fig. 2,. the container, ll isconnectedby meansoi' conduit I! with a. pressureregulator III. This regulator is similar toregulator I I shown in Fig. 1,. with the exception that the valve Ill establishes communication between theinterior oi the regulator casing and the conduit 82, instead or between the conduit l2. and conduit". Inotherwcrds, valve ll merely byrmthe throttle valve 36 and not ment oi. the arm" in a clockwise direction is .limited'by means oi a iixed member It, The opposite end of arm 11 ielormed 881811 electric cotztteirit l. which cooperates with a'flxed eon- A valve "controls communication between valve chamber "II and the space II to which is connected the tube 81. Valve II is mounted on a valve stem II which extends outside the valve chamber 13 and is provided with an armature I4 of an electro-magnet 88. Valve 82 is loaded in any suitable manner, as by a spring, so that a certain pressure differential is required to open it. A loaded valve 59 is provided for establishing a communication between space 66 and the atmosphere, as was the case in Fig. 1.

Pivoted arm 11 which carries contact 89 is connected by means of an electric conductor 86 with a suitable source of electric current, such as battery 81. The other terminal of the battery is connected by mans of a conductor 88 with one terminal of electro-magnet 85, a variable resistance 89 being connected in series in the circuit. The other terminal of the electro-magnet is connected by means of a conductor 99 with the contact 8|. A large capacity condenser 9| is connected between conductors 88 and 99. A circuit 92 is connected across the terminals of the electro-maget and includes -\a fixed contact 93 29 and a pivoted arm 94, the latter beingmovable with the button 34 of the valve 39 so as to close the circuit 92 and thus short-circuit the electromagnet.

The above described apparatus operates as 25 follows:

Gas under pressure is supplied from the container I9 to the conduit I2 to the pressure regulator 19, which is adjusted to maintain a pressure as for instance 5 mm. of water. The gas 0 flows from the regulator through throttle valve 36 and conduit 39 to conduit 1|. The bulb 12 being deflated, the weight 69 maintains the arm 11 in a position with the contacts 89 and 8| closed. The circuit including the battery 81 and 35 the electro-magnet 85 is thereby closed and the magnet is energized, thus attracting the arma-- the magnet de-energized, the valve 82 may be' opened by the patient inhaling through the mask 58, which serves to reduce the pressure acting 50 on the upper side of the valve sufliciently so that,

' in conjunction with the gas pressure acting on the lower side of the valve,'the latter opens against the force of the spring or other loading means. Thereafter, the patient may inhale 55 anesthetic until the supply contained in the bulb 12 has been depleted to such an extent, that, due to collapse of the bulb, the contacts 89 and 8| are again closed. Throttle valve 36 restricts the flow of gas to conduit 1| to such an extent that 60 the patient exhausts gas from the bulb 12 faster than it is supplied through valve 36. The closing of contacts 89 and BI causes the electromagnet to be energized and to close the valve 82. Thereafter if the patient continues to inhale 65ml! the mask she obtains fresh air through the valve 59, in the same manner as described in connection with Fig. 1.

In this embodiment the volume of the gas which thepatient may obtain at any one time 70 may be predetermined by the setting of the set screw 16, which determines the maximum volume of the bulb 12. The minimum lapse of time required between administrations of .the anesthetic may be determined'by the setting of the 75 variable resistance 89; as this determines the minimum length of time which the valve 82 remains closed under the influence of the electro-magnet.

In the event the physican desires to administer large quantities of anesthetic the button 34 is j depressed, which causes gas to be admitted to the conduit 1| at a faster rate inasmuch as throttle valve 36 is by-passed. Also, depression of the button 34 closes the circuit 92 and thus shortcircuits the electro-magnet, thereby rendering it 19- ineflective to maintain the valve 82 closed, regardless of whether or not contacts 89 and 8| are closed.

In the embodiment shown in Fig. 3, the container I9 is connected by means of a conduit I2 1 with a pressure regulator I4, of the type shown in Fig. 1. Conduit 28 connects the outlet of the pressure regulator with throttle valve 36 and conduit 39 connects the throttle valve with the valve chamber 49 formed within casing 4|.

The diaphragm 42 is mounted within casing 4| and is connected by means of arm 45 with the member 46 which is pivoted at 41 to the casing 4|. Member 46 carries valves 48 and 49 adjacent to one end and has its other end disposed between the poles 52 and 53 of the permanent magnet 54.

An electro-magnet 95 is arranged so as to magnetically attract member 46. Magnet 95 includes an energizing winding 96 and a shortcircuited winding 91. One terminal of the winding 96 is connected to a fixed contact 98 which cooperates with a pivoted switch arm 99 arranged in magnetic relation to the electromagnet so as to be moved away from contact 99, against the action of a spring I99,'under the magnet effect of the electro-magnet. Switch arm 99 is connected by means of a conductor I9| with one terminal of a battery I92. The other terminal of the battery is connected by means of a conductor I93 with a pivoted arm I94 which carries a contact I95 at one end. The other end of arm I94 is connected by means of a link I96 with the diaphragm 42. Contact I 95 cooperates with a fixed contact I91 which is connected by means of a conductor I98 with the other terminal of the winding 96, a variable resistance 99 being interposed in conductor I98. A condenser N9 of large capacity is connected across the terminals of the winding 96 and in series with the resistance I99.

The diaphragm chamber 59 is connected to a rubberbulb III, or the like, expansion of which in this embodiment is not restrained by means of fixed or adjustable plates. between chamber 5| and space 56 is controlled by the loaded valve 55, which is similar to the valve shown in Fig. 1. Space 561s connected by means of a tube 51 with the inhalation mask 58. The loaded valve 59 controls communica- 69 tion between space 56 and the atmosphere.

The operation of the above described device is as follows:

When the apparatus is first started the mem ber 46 is in the opposite position from that shown in Fig. 3, namely, with the valve 48 opened and the valve 49 closed and the opposite end of the member in contact with the pole 53 of the permanent magnet 54. Also, contacts I95 and I91 are closed due to the position of diaphragm 42 79 and contacts 98 and 99 are also closed, due to the fact that the electromagnet 95 has not been energized. Consequently, the circuit to the magnet is closed and the winding 96 is supplied with current. However, the short-circuited winding 91 Communication 55 delays the energizatlon of the electro-magnet' a suilicient length of time topermit the condenser ill to be charged. When the electro-magnet is 3 fully energized, it attracts switch arm 89 away from contactll thus opening. the battery circuit. However, the 'electro-magnet remains energized due to the discharge from the condenser llli, and consequently continues to attract the member 46. p p In the meantime gas isbeing supplied through conduit, l2, pressure regulator ll; conduit 28, throttle valve "and conduit 39 to the valve chamber II. The valve ll being open, the gas passes into diaphragm chamber SI and into bulb I ll. p

After a predetermined period of time, which may be regulated by the setting of the variable resistance m, thecondenser m becomes dis-, charged and hence electro-magnet ll becomes de-energized. When this happens the pressure acting on diaphragm 42 causes the latter to move to the left, asviewed in Fig. 3, thereby closing valve 48 and opening valve 4!, and also opening contacts llii and Ill. Upon the, de-energiza tion of the electro-magnet, the contacts 08 and, 89 are closed under the influence of spring A", p but the electro-magnet circuit remains open due to the open contacts I05 and I01. r

The pressure regulator I4 is set to maintain a pressure which is slightlylower than that required to open valve 55. However, as soon as the patient inhales, through themaskil, this reduces the pressure inthe space 56 suiliciently so that valve 55 is opened and 'gaspasses therefrom to the mask. 7 Flow of gas in this manner continues until the pressure has been reduced sufllciently inthef'diaphragm chamber to cause diaphragm 42 to move member 46 so as to close valve and open valve 48. This movement of the diaphragm also lcloses contacts Hi5 and I 01 p and the apparatus is in condition to repeat the above described cycle. p p

In this embodiment, as was the case in Fig.1, the minimum length of time between the periods I 5 in which the apparatus is capable oi supplying gas to the mask is determined by therate of flow through the throttle ,valve I6, and this may be adjusted by the. physician. In this. embodiment the volumeof gas available is determinedby the r setting of the variableresistance I09, inasmuch as thisdetermines the length of time; which the electro-magnet is energized,-and hence the length of time: which the valve ll is open. Obviously the longerthis valve is openthe moregaswill 86 flow into the expansible bulb Ill. Inasmuch as expansion of the bulb is not restrained by fixed or adjustable plates, the volume of gaswhich. will flow thereinto, at least within the limits of elasticity of the material of the bulb; is detere do mined by the length oi'time during which ilow is permitted, which, as above describedyis regulatedby thesetting'of the variable resistance I". If, in an emergency, .the physician wishes to administer larger ainountsof anesthetic, this may be done .by depressing button 34, thus opening valve 3| and permitting gas to flow directly from conduit I! to the valve chamber ,iis was thecaseinFlg. 1. Q

It will thusbe seen that in each oi! the three embodiments,herein disclosed, by way of example, the apparatus may be set bya physician or other skilled person so as to be capable oi SUDQ plying a predetermined maximum amount ofgas periodically, and the" minimum time betweenperiods may be similarly regulated. However, the

myinvention this hasbeen illustration only x not to be'considered as limiting the. scope of vention. r v

, chamber ,to said whenever said first valve is connecting said conduit with the the lastmentioned valve patient herself, determina the length 0! time,

above this minimum, between the periods.

While I have shown severalembodiments of done (or purposes 0! 1. In anapparatus, for administering a gaseous anaesthetic to a patient, an" expansible chamber, means for-supplying gas to said chamber, an;inhalation mask, conduit means tor convevingaas i'rom saidchamber to said mask, and

means automatically (operatingindependently of .thea'ction, offthe patient tor; interrupting the supply of gas to said mask for a predeterminable and appreciable minimum length or time when- I ever the expansible chamber wemptied oi gas.

2. Inan apparatus m administering a gaseous anestheticto a patient, an expansible chamber,gmeans for supply ng I8 tosaid chamber, meanstor automatically interrupting the flow or gas to, said. ;chamber when ;a predetermined amount has been supplied, aninhalation mask. conduit means i 'or conveying gas from said chamber to said mask,and means automatically operating independently of the actionoi' the patient for interruptinglthe supply or gas to said mask foran appreciable minimum length at time whenever the expansible chamber is? emptied of 3. In an apparatus for administering a gas- .eousanesthetic, an expansible chamber, means for suppLving gas to said chamber, an inhalation mask, a conduit for conveying as from said chamber to said mask, .a first valvein said conduit, means for maintaining said: valve closed for a predetermined lengthoi' time after said chamber has been emptied, and a second valve insaid conduit 1operab1e under the control of the patient. l

4. In an apparatus for ldministering a gaseous anesthetic, an expansible chamber, means for supplying gas tosaid chamber, an inhalation mask, a conduit for, conveyinggas irom said mask, a first valvein said conduit, means for maintaining :said valve closed for a predetermined length of :time ai'ter said chamber haslbeen emptied, a second valve in said conduit operable 1 under control of the patient open, and a valve atmosphere and operable under control; oi the. patient whenever said first valve is closed. a,

5. In. an apparatusior administering a gaseous anesthetic, an expansible chamber, means for supplying gas tosaid chamber at an adjustable rate and under a predetermined pressure, an inhalation mask, va conduit for conveying gas from said chamber to said mask, a first valve in said conduit, means for opening saidvalve when said pressure is attained in said chamber, a'second valve in'said conduit, means forloa'ding said second valveisoathat it remains closed under said pressure and opens under the increased pressure differential: resulting from the patient inhaling through saidmask, a valve connectlngsaid conduitwith the atmosphereqand meansftor loading so that a greater pressure differential is required to open it than is required .to opensaid second valve.

8. In an apparatusi'or administering agaseous: anesthetic, an expansible chamber, a conduit for supplying gas to said chamber, means for regulating the rate oi i low of gas through said conduit, an inhalation mask, cnnduitmeans for conveying gas from said chamber to said mask, and means responsive to the rate of flow of gas through said firstmentioned conduit for interrupting the supply of gas to said mask for a minimum length of time.

7 In an apparatus for administering a gaseous anesthetic, an expansible chamber, means for supplying gas to said chamber, an inhalation mask, conduit means for conveyin gas from said chamber to said mask, a diaphragm subjected to .the pressure of the gas in said chamber, a valve for controlling the supply of gas to said chamber operable by said diaphragm so as to be closed upon an increase in pressure, a valve for controlling the flow of gas from said chamber to said mask operable -by said diaphragm so as to be closed upon a decrease in pressure, and means for regulating the rate at which gas is supplied to said chamber when the first mentioned valve is open to thereby determine the length of time the second mentioned valve is maintained closed.

8. In an apparatus for administering a gaseous anesthetic, an expansible chamber, means for supplying gas to said chamber, an inhalation mask, a conduit for conducting gas from said chamber to said mask, a valve in said conduit, and means for maintaining said valve closed when said chamber is deflated and for a minimum length of time after said chamber is expanded.

9. In an apparatus for administering a gaseous anesthetic, an expansible chamber, means for supply g gas to said chamber under a predetermined pressure, an inhalation mask, a conduit for conducting gas from said chamber to said mask,

a valve in said conduit, means for maintaining said valve closed when said chamber is deflated and for a minimum length of time after said chamber is expanded, and means for permanently applying a force to said valve tending to maintain it closed, said force being greater than the force exerted on the valve by the gas under said pressure and less than the force exerted on the valve caused by the pressure difierential resulting from the patient inhaling through said mask.

10. In an apparatus for administering a gaseou-s anesthetic, an expansible chamber, means for supplying gas to said chamber, an inhalation mask, a conduit for conducting gas from said chamber to said mask, a valve in said conduit, an electro-magnet for maintaining said valve'closed, means for energizing said electro-magnet when saidchamber is deflated, and an electric condenser for maintaining said electro-magnet energized for a predetermined length of time after said chamber is expanded.

11. In an apparatus for administering a gaseous anesthetic, an expansible chamber, a conduit for supplying gas to said chamber, an adjustable throttle valve for regulating the rate of flow of gas through said conduit, an inhalation mask, conduit means for conveying gas from said chamber to said mask, means responsive to the rate of flow of gas through said first mentioned conduit for interrupting the supply of gas to said mask for a minimum length of time, and means for by-passing said throttle valve to supply gas at an increased rate to said chamber.

12. In an apparatus for administering a gaseous anesthetic, an expansible chamber, a conduit for supplying gas ,to said chamber, an adjustable throttle valve in said conduit, an inhalation mask, a conduit for conducting gas from said chamber to said mask, a valve in the last mentioned conduit, means for maintaining the last mentioned valve closed when said chamber is deflated and for a minimum length of time after said chamber is expanded, and means for by-passing said throttle valve and for rendering the last mentioned means inoperative, whereby an increased quantity of gas is supplied continuously to said mask.

13. In an apparatus for administering a gaseous anesthetic, an expansible chamber, a conduit for supplying gas to said chamber, an adjustable throttle valve in said conduit, an inhalation mask, a conduit for conducting gas from said chamber to said mask, a valve in the last mentioned conduit, an electro-magnet for maintaining the last mentioned valve closed, means for energizing said electro-magnet when said chamber is deflated, an electric condenser for maintaining said electro-magnet energized for a predetermined length of time after said chamber is expanded, and means for by-passing said throttle valve and for maintaining said electromagnet deenergized, whereby an increased quantity of gas is supplied continuously to said mask.

EMlL EINAR WILHELM ANDERSON.

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Classifications
U.S. Classification128/204.21, 128/203.13, 128/205.14
International ClassificationA61M16/10
Cooperative ClassificationA61M16/104
European ClassificationA61M16/10B