US2891542A - Infant anesthetic machine - Google Patents

Description

June 23, 1959 5, PENTECOST 2,891,542

INFANT ANESTHETIC MACHINE Filed Oct. 25, 1956 FIG-.3

INVENTOR. F3404 RF/YTECOS 7' A T 70 Emma United States Patent INFANT ANESTHETIC MACHINE Paul S. Pentecost, San Diego, Calif.

Application October 25, 1956, Serial No. 618,260

4 Claims. (Cl. 128-188) My invention comprises an anesthesior and more specifically a device for giving anesthetic to extremely young infants.

In administering anesthetic to extremely small infants, there is one serious difliculty and danger. The tidal volume (number of cc. of gas inhaled or exhaled during normal breathing) of an infant may be very small (9 to 17 cc.). The mechanical dead space may be several times this volume. As a result, the infant rebreathes gases from this mechanical dead space. The carbondioxide content of the gases increases, the oxygen content diminishesleading to respiratory acidosis and hyoxia respectively.

It is, therefore, the purpose of my invention to reduce the mechanical dead space to as small a volume as possible (7.5 cc.).

It is another object of my invention to provide an anesthesior which prevents accumulation of exhaled gases in the mechanical dead space no matter the size of the patient upon which the machine is used.

Other advantages of my invention will be apparent from the following disclosure of the preferred embodiments thereof.

In the drawings:

Figure 1 is an elevation of my anesthesior.

Figure 2 is a schematic view in cross section of the valve arrangements.

An anesthesior constructed in accordance with my invention has an inlet 1, for the admission of anesthetic agents and oxygen. From the inlet 1, the gases pass through a venturi nozzle 2, and blow into a venturi tube 3, then through the passage 4, past a flutter valve 5 and into the chamber 6, through outlet 7, connected to an endotracheal tube to the patient.

During the exhalation cycle, the gases pass from the endotracheal tube into the chamber 6, through flutter valve 8, through the passage 9, through soda lime canister 10, through soda lime 11 where carbon dioxide is removed. From the canister 10, the gases pass into tube 12. Tube 13, which is the entraining tube connected to the venturi tube, extends through tube 16 into tube 12, the exhalation side of the system. The gases which enter through inlet 1, venturi nozzle 2 into the venturi tube 3 create negative pressure in tube 13. The negative pressure thus produced pullls the exhaled gases from the chamber 6, thus preventing accumulation of carbondioxide in this ordinarily dead space. From tube 12 part of the gases enter the entraining tube 13, part flows through tube 16, around tube 13 into tube 4. Part continues on into rebreathing bag 15 and the excess blows out exhalation valve 14.

In prior anesthesiors for infants, the chamber 6 comprises a mechanical dead space. The volume of this ice 2 chamber 6 exceeded the tidal volume of the infant. As a result, the infant rebreathes the gases. As a result,

the CO accumulation caused respiratory acidoses. Also, the partial pressure of oxygen was gradually reduced, resulting in partial, if not complete, asphyxia over a period of time.

The rebreathing bag has a tail pipe 17, which can be connected by means of rubber tubing to a pressure manometer. Thus, a careful check can be made continuously of positive pressure in the anesthesior.

I claim:

1. In an anesthetic machine for infant patients, a gas inlet, a venturi connected to said inlet, a chamber having a volume smaller than the tidal volume of the infant patient, a passage from said venturi to said chamber, an outlet from said chamber to means for delivery to a patient, a backflow preventing valve between said chamber and said passage, a canister to hold carbon dioxide removing chemicals, a passage from said chamber to said canister, a backfiow preventing valve between said canister and said chamber, a breathing bag, a tube connecting said canister and said breathing bag, and a passage to port gases from said tube through said venturi.

2. An anesthetic machine for use with infant patients comprising a chamber, said chamber having means to connect a delivery device to said patient, means for porting an anesthetic gas to said chamber, a venturi in said means, a valve between said means and said chamber to prevent backflow, exhaust means for porting the exhaust gases from said chamber, a valve in said exhaust means to prevent backfiow, means connecting said exhaust means with said venturi whereby circulation is maintained in said exhaust means, said chamber having a volume smaller than the tidal volume of the infant patient.

3. An anesthetic machine for use with infant patients comprising a chamber, said chamber having means to connect a delivery device to said patient, means for porting an anesthetic gas to said chamber, a venturi in said means, a valve between said means and said chamber to prevent backflow, exhaust means for porting the exhaust gases from said chamber, a valve in said exhaust means to prevent backfiow, means connecting said ex haust means with said venturi whereby circulation is maintained in said exhaust means, said chamber having a volume of 7.5 cc.

4. In an anesthetic machine for infant patients, a gas inlet, a venturi connected to said inlet, a chamber having a volume of 7.5 cc., a passage from said venturi to said chamber, an outlet from said chamber to means for delivery to a patient, a backflow preventing valve between said chamber and said passage, a canister to hold carbon dioxide removing chemicals, a passage from said chamber to said canister, a backfiow preventing valve between said canister and said chamber, a breathing bag, a tube connecting said canister and said breathing bag, and a passage to port gases from said tube through said venturi.

References Cited in the file of this patent UNITED STATES PATENTS 2,216,183 Connell Oct. 1, 1940 FOREIGN PATENTS 429,276 Great Britain May 28, 1935 1,068,330 France Feb. 3, 1954

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