Inspiration oxygen saver

• US 4,932,402 A
• Filed: 10/16/1987
• Issued: 06/12/1990
• Est. Priority Date: 04/11/1986
• Status: Expired due to Term

• Current Assignee: Puritan Bennett Corp. (Medtronic Plc)
• Original Assignee: Puritan Bennett Corp. (Medtronic Plc)
• Inventors: Wyble, Marilyn S., Snook, James A., Nelson, Thomas W., Trimble, Russell L.
• Primary Examiner(s): Jaworski, Francis
• Assistant Examiner(s): MANUEL, GEORGE C
• Application Number:
  US07/108,948
• Time in Patent Office: 970 Days
• Field of Search: 128/204.23, 128/205.11, 128/204.26, 128/205.14, 364/413.01, 364/413.02, 364/413.03, 364/413.3
• US Class Current: 128/204.23
• CPC Class Codes: A61M 16/0051 with alarm devices
• CPC Class Codes: A61M 16/024 including calculation means, e.g. using a processor
• CPC Class Codes: A61M 16/0677 Gas-saving devices therefor
• CPC Class Codes: A61M 16/101 using an oxygen concentrator
• CPC Class Codes: A61M 16/107 in the inspiratory path
• CPC Class Codes: A61M 2016/0021 with a proportional output signal, e.g. from a thermistor
• CPC Class Codes: A61M 2016/0039 in the inspiratory circuit

Abstract

A reliable, pulse-flow supplemental oxygen apparatus for alleviating respiratory ailments is provided which yields substantial savings in oxygen while giving the patient the physiological equivalent of a prescribed continuous stream of oxygen. The apparatus preferably includes a demand oxygen valve operated in a pulse mode by means of electronic control circuitry which, through an appropriate sensor, monitors the patient'"'"'s breathing efforts and gives a variable "custom tailored" pulse volume of oxygen to the patient during the very initial stages of each inspiration. Pulse volume variability is based upon a measured parameter characterizing at least a part of one and preferably a plurality of the patient'"'"'s preceding breaths; advantageously, the elapsed time interval of the patient'"'"'s three preceding breath cycles is measured to effectively measure breath rate. These breath-characterizing parameters, together with data characterizing the prescribed continuous oxygen flow to be matched, enable the apparatus to give the desired "on the go" dose variability. The apparatus is also designed to revert to conventional, continuous-flow operation upon a power failure or circuit malfunction, and for this purpose a specialized dual flow control restrictor valve is provided in the form of the invention designed for hospital use. In the event of abnormally low or high breath rates on the part of the patient, the device automatically delivers a relatively long continuous pulse, then stops to again sample the breath rate. If the rate is normal, the usual pulse flow operation is resumed; if the rate remains abnormal, the long pulse volume-rate sampling is repeated. Actual tests with the apparatus hereof demonstrate an oxygen saving of over 50% as compared with continuous flow regimens.

Claims

1. A pulse translation apparatus for translating a series of input signals occurring at variable time intervals into a series of corresponding output signals such that each of the output signals commences in predetermined time relationship to the occurrence of a corresponding input signal and represents a time duration correlated in predetermined manner with the time intervals corresponding to a predetermined plurality if preceding input signals, said apparatus comprising:

input means for receiving said input signals;

output means for delivering said output signals;

a plurality of timer means greater in number than said predetermined plurality of preceding input signals, and each operable for measuring a time interval between events characterizing the occurrence of the first and last signals of said predetermined plurality of preceding input signals, and for generating an output signal representative of a time duration correlated in predetermined manner with said time interval;

means for sequentially coupling each of said timer means with said input means in response to a successive one of said input signals; and

means for sequentially decoupling each of said timer means from said input means, and for sequentially coupling each of said timer means with said output means in response to the last signal of said predetermined plurality of input signals.

2. The apparatus as set forth in claim 1, including means for delivering clock signals at regular intervals to each of said timer means,

each of said timer means including means for receiving and counting said clock signals for said time interval to produce a total count of said clock signals received during said time interval,

said output signals being representative of said total count.

3. The apparatus as set forth in claim 2, said input, output and clock signals being electrical digital signals.

4. The apparatus as set forth in claim 2, said apparatus including four timer means.

5. In an apparatus for delivering medicinal gas to a patient, said apparatus having means for tracking the breathing efforts of the patient and for producing a plurality of breath cycle signals corresponding to a predetermined event in each of a plurality of patient breathing cycles, a method of using said apparatus for determining the breathing rate of the patient comprising the steps of:

(a) starting one of a plurality of timers upon the occurrence of a first one of a plurality of said breath cycle signals;

(b) stopping said one time upon the occurrence of a subsequent breath cycle signal, said subsequent breath cycle signal being at least the second signal after said first signal,

(c) producing an output signal representative of the time interval between said first one and said subsequent breathing cycle signals, said output signal being correlated with and representative of the patient'"'"'s breathing rate,

(d) continuously repeating steps (a), (b), and (c) for each of said plurality of timers upon the occurrence of successive breath cycle signals respectively.

6. The method as set forth in claim 5, wherein said first one of said breath cycle signals corresponding to each of said timers are consecutive breath cycle signals.

7. The method as set forth in claim 5, said plurality of timers including at least three timers, said subsequent breathing cycle signal being the sequentially subsequent signal equal to the number of said timers less one.

8. An apparatus for translating a series of input signals occurring at variable time intervals into a series of corresponding output signals wherein the series input signals presents a plurality of sets of input signals with each set having a predetermined plurality of input signals included therein, and in which each output signal is associated with an input signal set and represents the time interval between the first and the last input signals of an associated set, said apparatus comprising:

a plurality of selectively activatable and deactivatable timer means greater in number than said predetermined plurality,

each of said timer means including means for producing an output signal representative of the time interval between activation and deactivation thereof; and

input means operably coupled with said timer means for receiving the input signals and for activating each timer means in response to the first input signal of the set respectively associated therewith, and for deactivating each timer means in response to the last input signal of the set respectively associated therewith whereby each of said timer means produces a respective output signal representative of the time interval between the first and last input signal of an associated set of input signals and thereby representative of an average of variable time intervals between input signals included in the associated set.

9. The apparatus as set forth in claim 8, the respective first input signals of the sets being sequential input signals and said timer means being one greater in number than said predetermined plurality wherein said timer means produce respective sequential output signals representative of the respective time intervals between the first and last input signals of the respectively associated sets and thereby representative of a moving average of the variable time intervals of the predetermined plurality of input signals.

10. The apparatus as set forth in claim 9, including four of said timer means.

11. The apparatus as set forth in claim 8, said timer means including solid state digital timers.