Process control and apparatus for ventilation procedures with helium and oxygen mixtures

• US 5,429,123 A
• Filed: 12/15/1993
• Issued: 07/04/1995
• Est. Priority Date: 12/15/1993
• Status: Expired due to Term

• Current Assignee: Temple University of The Commonwealth System of Higher Education
• Original Assignee: Temple University of The Commonwealth System of Higher Education
• Inventors: Wolfson, Marla R., Shaffer, Thomas H.
• Primary Examiner(s): Asher, Kimberly L.
• Application Number:
  US08/167,680
• Time in Patent Office: 566 Days
• Field of Search: 128/204.18, 128/204.21-204.23, 128/205.11, 128/205.23, 128/205.24, 128/207.18, 128/205.26, 128/205.25
• 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 16/0627 with sealing means on a part of the body other than the face, e.g. helmets, hoods or domes
• CPC Class Codes: A61M 16/1065 in the expiratory path
• CPC Class Codes: A61M 16/12 by mixing different gases
• CPC Class Codes: A61M 16/16 Devices to humidify the respiration air A61M16/1045 takes precedence
• CPC Class Codes: A61M 16/161 with means for measuring the humidity
• CPC Class Codes: A61M 16/22 Carbon dioxide-absorbing devices ; Other means for removing carbon dioxidecartridges with absorbing substances for respiratory apparatus A62B19/00
• CPC Class Codes: A61M 2016/0036 in the breathing tube and used in both inspiratory and expiratory phase
• CPC Class Codes: A61M 2016/102 Measuring a parameter of the content of the delivered gas
• CPC Class Codes: A61M 2016/1025 the O2 concentration
• CPC Class Codes: A61M 2205/3368 Temperature
• CPC Class Codes: A61M 2205/36 related to heating or cooling
• CPC Class Codes: A61M 2230/432 partial CO2 pressure (P-CO2)
• CPC Class Codes: A61M 2230/435 partial O2 pressure (P-O2)
• CPC Class Codes: A61M 2230/50 Temperature

Abstract

A process is provided for controlling a ventilation procedure wherein a heliox ventilation system passes a breathing medium through at least a portion of a patient'"'"'s pulmonary pathways. In this process, desired ranges for certain process parameters associated with the heliox ventilation system are established. These desired ranges are input into a signal processor. Initial settings for the heliox ventilation system are then made such that the actual conditions which will initially occur during the heliox ventilation procedure fall within their respective desired ranges. Thereafter, the heliox ventilation procedure is commenced. During the heliox ventilation procedure, conditions which relate to the established ranges are continually monitored by appropriate sensors. The monitored information is also input into the signal processor. The signal processor is designed to compare the actually-occurring monitored conditions to their respective desired ranges and determine if there is a difference therebetween. If there is a difference, the signal processor generates signals which are designed to correct the discrepancy. These signals can be designed to trigger alarms which instruct an operator to make the appropriate adjustments and/or to activate a servo-controlled valving network. By practicing this invention, it is possible to maintain proper oxygenation levels in a patient ventilated with a heliox ventilation system while minimizing lung compliance and lung resistance levels.

Claims

1. A process for guiding, monitoring and regulating a heliox ventilation system wherein said ventilation system is designed to circulate a breathing medium comprising gaseous helium and gaseous oxygen through at least a portion of a patient'"'"'s pulmonary pathways, and wherein said heliox ventilation system includes a gas mechanics circuit component, a gas concentration circuit component and a temperature/humidification circuit component, said process comprising the steps of:

(a) establishing a set of desired ranges for process parameters associated with the gas mechanics circuit, the gas concentration circuit and the temperature/humidification circuit components of said heliox ventilation system, said set of established desired ranges are represented by a first set of signals;

(b) inputting the first set of signals in to a signal processor,

(c) making initial adjustments to the gas mechanics circuit, the gas concentration circuit and the temperature/humidification circuit components of said heliox ventilation system, said initial adjustments are such that actual conditions of said heliox ventilation system'"'"'s gas mechanics circuit, gas concentration circuit and temperature/humidification circuit components, which occur while a breathing medium circulates through at least a portion of the patient'"'"'s pulmonary pathways, fall within the purview of their corresponding established desired ranges, said initial adjustments establish the patient'"'"'s initial ventilatory profile;

(d) preparing a breathing medium comprising gaseous helium and gaseous oxygen;

(e) circulating the breathing medium through at least a portion of the patient'"'"'s pulmonary pathways in accordance with said initial adjustments made to the gas mechanics circuit, the gas concentration circuit and the temperature/humidification circuit components of said heliox ventilation system;

(f) monitoring a set of actual conditions of said heliox ventilation system'"'"'s gas mechanics circuit, gas concentration circuit and temperature/humidification circuit components which occur while said breathing medium is circulating through at least a portion of the patient'"'"'s pulmonary pathways, said monitored set of actual conditions correspond with said set of established desired ranges, and said set of monitored actual conditions being represented by a second set of signals;

(g) inputting the second set of signals into said processor;

(h) implementing said signal processor to determine whether said second set of signals fall within the purview of their corresponding ranges represented by said first set of signals, instances wherein said second set of signals fall outside of said first set of signals are represented by a third set of signals; and

(i) implementing said third set of signals to manipulate said initial adjustments such that said second set of signals fall within the purview of their corresponding ranges represented by said first set of signals.

2. A process in accordance with claim 1 wherein the gas mechanics circuit component of said heliox ventilation system is designed to regulate the circulation of said breathing medium through at least a portion of the patient'"'"'s pulmonary pathways by utilizing information gained from an on-line assessment of the breathing medium'"'"'s pressures, flow rates and volumes.

3. A process in accordance with claim 2 wherein the gas mechanics circuit component of said heliox ventilation system utilizes information gained from an assessment of respiratory gas levels contained in samples of said breathing medium before it is inspired by said patient and after it is expired by the patient.

4. A process in accordance with claim 1 wherein the gas concentration circuit component of said heliox ventilation system is designed to regulate the partial pressures, tensions and concentrations of gases in the heliox ventilation system'"'"'s gas concentration circuit component and gas mechanics circuit component, as well as in the patient, by utilizing information gained from an on-line assessment of inspiratory and expiratory gas levels contained in at least the following areas:

in samples of gases before being blended to form the breathing liquid, in samples of the breathing medium prior to it being inspired by the patient, in samples of the breathing medium after being expired by the patient, and in samples of the blood taken from the patient'"'"'s circulatory, system while said breathing medium is circulating through at least a portion of the patient'"'"'s pulmonary pathways.

5. A process in accordance with claim 4 wherein tracer gases are blended with said breathing medium prior to it being inspired by the patient, and wherein the gas concentration circuit component of said heliox ventilation system utilizes information gained from an on-line assessment of said tracer gases to determine at least one physiological parameter selected from the group consisting of:

oxygen consumption, carbon dioxide production, respiratory quotient, cardiac output, effective pulmonary blood flow, diffusional dead space, anatomic dead space, intrapulmonary and extrapulmonary shunts, diffusion capacity and lung tissue water.

6. A process in accordance with claim 1 wherein the temperature/humidification circuit component of said heliox ventilation system is designed to regulate at least a portion of the patient'"'"'s internal and external body temperatures while said breathing medium is being circulated through at least a portion of the patient'"'"'s pulmonary pathways by utilizing information gained from temperature sensing means in or on appropriate body parts, organs and regions of the patient.

7. A process in accordance with claim 1 wherein the temperature/humidification circuit component of said heliox ventilation system is designed to regulate the humidity level of the breathing medium prior to it being inspired by the patient by utilizing information gained from an on-line assessment of the breathing medium.

8. A process in accordance with claim 1 wherein at least the following initial adjustments are made to the gas mechanics circuit, gas concentration circuit and temperature/humidification circuit components of the heliox ventilation system prior to the breathing medium being circulated through at least a portion of the patient'"'"'s pulmonary pathways:

a starting lung volume, the breathing medium'"'"'s initial pressure, initial tidal lung volume, the breathing medium'"'"'s initial flow rate, an initial concentration of oxygen in a specific volume of said breathing medium prior to said breathing medium being inspired by the patient, a resting lung volume, a peak inspiratory air way pressure, a peak expiratory air way pressure, a peak alveolar pressure, a peak esophageal pressure, an initial breathing frequency, a timing ratio of inspiratory-to-expiratory gas flow, the patient'"'"'s core body temperature, and the temperature of the breathing medium prior to it being inspired by the patient.

9. A process in accordance with claim 1 wherein establishing a set of desired ranges for process parameters associated with the gas mechanics circuit component of said heliox ventilation system includes establishing minimum and maximum values for at least the following:

the breathing medium'"'"'s pressure for when it is being circulated through at least a portion of the patient'"'"'s pulmonary pathways, the breathing medium'"'"'s tidal lung volume for when it is being circulated through at least a portion of said patient'"'"'s pulmonary pathways, the breathing medium'"'"'s resting lung volume for when it is being circulated through at least a portion of the patient'"'"'s pulmonary pathways, the breathing medium'"'"'s flow rate for when it is being circulated through at least a portion of the patient'"'"'s pulmonary pathways, an amount of oxygen to be absorbed by the patient from a specific volume of said breathing medium as said breathing medium is being circulated through at least a portion of the patient'"'"'s pulmonary pathways, and an amount of carbon dioxide to be carried from the patient by a specific volume of said breathing medium as said breathing medium is being circulated through at least a portion of the patient'"'"'s pulmonary pathways.

10. A process in accordance with claim 1 wherein establishing a set of desired ranges for process parameters associated with the gas concentration circuit component of said heliox ventilation system includes establishing minimum and maximum values for at least the following:

a concentration of oxygen in a specific volume of gas being blended to form said breathing medium, a concentration of oxygen in a specific volume of said breathing medium prior to said breathing medium being inspired by the patient, a concentration of oxygen in a specific volume of said breathing medium after said breathing medium is expired by the patient, a concentration of carbon dioxide in a specific volume of said breathing medium after said breathing medium is expired by the patient, and a concentration of oxygen in the patient'"'"'s circulatory system while said breathing medium is being circulated through at least a portion of the patient'"'"'s pulmonary pathways.

11. A process in accordance with claim 1 wherein establishing a set of desired ranges for process parameters associated with the temperature/humidification circuit component of said heliox ventilation system includes establishing minimum and maximum values for at least the following:

the breathing medium'"'"'s temperature prior to said breathing medium being inspired by the patient, the breathing medium'"'"'s humidity prior to said breathing medium being inspired by the patient, the patient'"'"'s internal body temperature while said breathing medium is being circulated through at least a portion of the patient'"'"'s pulmonary pathways, and the patient'"'"'s external body temperature of while said breathing medium is being circulated through at least a portion of the patient'"'"'s pulmonary pathways.

12. A ventilator system for blending a mixture of at least gaseous helium and gaseous oxygen to form a helium-oxygen blend and for automatically controlling the administration of the helium-oxygen blend into at least a portion of a patient'"'"'s pulmonary air pathways such that physiological homeostasis is maintained, at reduced lung pressures and resistances, within the patient with respect to helium-oxygen blend gas flows, gas volumes and gas pressures, with respect to helium and oxygen concentrations in the helium-oxygen blend, with respect to heat exchange and humidification means between the helium-oxygen blend and the patient, and with respect to the patient'"'"'s body temperature during ventilation, said ventilation system comprising:

(a) gaseous helium pressure control means for providing a pressure regulated source of gaseous helium;

(b) gaseous oxygen pressure control means for providing a pressure regulated source of gaseous oxygen;

(c) blending means designed to blend gaseous helium and gaseous oxygen together to form a gaseous helium-oxygen blend;

(d) helium flow control means for controlling the rate at which gaseous helium flows into said blending means, said helium flow control means being in gaseous communication with said helium source and said blending means;

(e) oxygen flow control means for controlling the rate at which gaseous oxygen flows into said blending means, said oxygen flow control means being in gaseous communication with said oxygen source and said blending means;

(f) respiration receptacle in gaseous communication with said blending means and at least a portion of a patient'"'"'s pulmonary air pathways;

(g) temperature adjusting means for controlling the temperature level of the helium-oxygen blend within said respiration receptacle;

(h) humidification adjusting means for controlling the humidity level of the helium-oxygen blend within said respiration receptacle;

(i) helium-oxygen blend flow control means for controlling the rate at which the helium-oxygen blend flows into said respiration receptacle;

(j) inspiration volume control means for controlling the volume of said helium-oxygen blend inspired during the inspiratory portion of a patient'"'"'s breathing cycle;

(k) expiration volume control means for controlling the volume of gas expired during the expiratory portion of a patient'"'"'s breathing cycle;

(l) first means for selecting a desired concentration of gaseous helium in said helium-oxygen blend as said helium-oxygen blend is in said respiration receptacle and generating a first signal having a value indicative of said desired helium concentration in said helium-oxygen blend;

(m) second means for selecting a desired concentration of gaseous oxygen in said helium-oxygen blend as said helium-oxygen blend is in said respiration receptacle and generating a second signal having a value indicative of said desired oxygen concentration in said helium-oxygen blend;

(n) third means for selecting a desired helium-oxygen blend flow rate from said respiration receptacle into at least a portion of the patient'"'"'s pulmonary pathways and generating a third signal having a value indicative of said helium-oxygen blend desired flow rate;

(o) forth means for selecting a desired temperature level of said helium-oxygen blend prior to said helium-oxygen blend being inspired by the patient and a fifth means for selecting a desired temperature level of said gas being expired by the patient, said forth means generates a forth signal having a value indicative of said helium-oxygen blend desired temperature level and said fifth means generates a fifth signal having a value indicative of said expired gas desired temperature level;

(p) sixth means for selecting a desired humidification level of said helium-oxygen blend prior to said helium-oxygen blend being inspired by the patient, said sixth means generates a sixth signal having a value indicative of said helium-oxygen blend desired humidification level;

(q) seventh means for selecting a desired temperature level of at least a portion of a patient'"'"'s pulmonary pathways as the patient is being ventilated with said helium-oxygen blend and generating a seventh signal having a value indicative of the patient'"'"'s pulmonary pathways desired temperature level;

(r) eighth means for selecting a desired pressure level of said helium-oxygen blend as said helium-oxygen blend is passing from said respiration receptacle to the patient'"'"'s pulmonary pathways and a ninth means for selecting a desired pressure level of said gas being expired by the patient, said eighth means generates an eighth signal having a value indicative of said helium-oxygen blend desired pressure level and said ninth means generates a ninth signal having a value indicative of said expired gas desired pressure level;

(s) tenth means for selecting a desired volume of said helium-oxygen blend to be inspired by the patient and an eleventh means for selecting a desired volume of said gas being expired by the patient, said tenth means generates a tenth signal having a value indicative of said helium-oxygen blend desired volume and said eleventh means generates an eleventh signal having a value indicative of said expired gas desired volume;

(t) twelfth means for selecting a desired concentration of gaseous oxygen in said expired gas and generating a twelfth signal having a value indicative of said desired oxygen concentration in said expired gas;

(u) thirteenth means for selecting a desired concentration of oxygen in a preselected portion of the patient'"'"'s circulatory system while the patient is ventilated with said helium-oxygen blend and generating a thirteenth signal having a value indicative of said desired oxygen concentration in the patient;

(v) fourteenth means for detecting the actual concentration of gaseous helium in said helium-oxygen blend as said helium-oxygen blend is in said respiration receptacle and generating a fourteenth signal having a value indicative of said actual helium concentration in said helium-oxygen blend;

(w) fifteenth means for detecting the actual concentration of gaseous oxygen in said helium-oxygen blend as said helium-oxygen blend is in said respiration receptacle and generating a fifteenth signal having a value indicative of said actual oxygen concentration in said helium-oxygen blend;

(x) sixteenth means for detecting the actual rate at which said helium-oxygen flows from said respiration receptacle into at least a portion of the patient'"'"'s pulmonary pathways and generating a sixteenth signal having a value indicative of said helium-oxygen blend actual flow rate;

(y) seventeenth means for detecting the actual temperature of said helium-oxygen blend prior to said helium-oxygen blend being inspired by the patient and an eighteenth means for detecting the actual temperature of said gas being expired by the patient, said seventeenth means generates a seventeenth signal having a value indicative of said helium-oxygen blend actual temperature and said eighteenth means generates an eighteenth signal having a value indicative of said expired gas actual temperature;

(z) nineteenth means for detecting the actual humidity of said helium-oxygen blend prior to said helium-oxygen blend being inspired by the patient and generating a nineteenth signal having a value indicative of said helium-oxygen blend actual humidity;

(aa) twentieth means for detecting the actual temperature of at least a portion of a patient'"'"'s pulmonary pathways as the patient is being ventilated with said helium-oxygen blend and generating a twentieth signal having a value indicative of the patient'"'"'s pulmonary pathways actual temperature;

(bb) twenty-first means for detecting the actual pressure of said helium-oxygen blend as said helium-oxygen blend is passing from said respiration receptacle to the patient'"'"'s pulmonary pathways and a twenty-second means for detecting the actual pressure of said gas being expired by the patient, said twenty-first means generates a twenty-first signal having a value indicative of said helium-oxygen blend actual pressure and said twenty-second means generates a twenty-second signal having a value indicative of said expired gas actual pressure;

(cc) twenty-third means for detecting the actual volume of said helium-oxygen blend being inspired by the patient and a twenty-forth means for detecting the actual volume of said gas being expired by the patient, said twenty-third means generates a twenty-third signal having a value indicative of said helium-oxygen blend actual volume and said twenty-forth means generates a twenty-forth signal having a value indicative of said expired gas actual volume;

(dd) twenty-fifth means for detecting the actual concentration of gaseous oxygen in said expired gas and generating a twenty-fifth signal having a value indicative of said actual oxygen concentration in said expired gas;

(ee) twenty-sixth means for detecting the actual concentration of oxygen in a preselected portion of the patient'"'"'s circulatory system while the patient is ventilated with said helium-oxygen blend and generating a twenty-sixth signal having a value indicative of said actual oxygen concentration in the patient;

(ff) twenty-seventh means for comparing the first signal to the fourteenth signal and generating a twenty-seventh signal having a value indicative of the difference therebetween;

(gg) twenty-eighth means for comparing the second signal to the fifteenth signal and generating a twenty-eighth signal having a value indicative of the difference therebetween;

(hh) twenty-ninth means for comparing the third signal to the sixteenth signal and generating a twenty-ninth signal having a value indicative of the difference therebetween;

(ii) thirtieth means for comparing the forth signal to the seventeenth signal and generating a thirtieth signal having a value indicative of the difference therebetween;

(jj) thirty-first means for comparing the fifth signal to the eighteenth signal and generating a thirty-first signal having a value indicative of the difference therebetween;

(kk) thirty-second means for comparing the sixth signal to the nineteenth signal and generating a thirty-second signal having a value indicative of the difference therebetween;

(ll) thirty-third means for comparing the seventh signal to the twentieth signal and generating a thirty-third signal having a value indicative of the difference therebetween;

(mm) thirty-forth means for comparing the eighth signal to the twenty-first signal and generating a thirty-forth signal having a value indicative of the difference therebetween;

(nn) thirty-fifth means for comparing the ninth signal to the twenty-second signal and generating a thirty-fifth signal having a value indicative of the difference therebetween;

(oo) thirty-sixth means for comparing the tenth signal to the twenty-third signal and generating a thirty-sixth signal having a value indicative of the difference therebetween;

(pp) thirty-seventh means for comparing the eleventh signal to the twenty-forth signal and generating a thirty-seventh signal having a value indicative of the difference therebetween;

(qq) thirty-eighth means for comparing the twelfth signal to the twenty-fifth signal and generating a thirty-eighth signal having a value indicative of the difference therebetween;

(rr) thirty-ninth means for comparing the thirteenth signal to the twenty-sixth signal and generating a thirty-ninth signal having a value indicative of the difference therebetween;

(ss) fortieth means responsive to said twenty-seventh signal, said fortieth means being designed to manipulate the helium flow control means until there is no significant difference between the first signal and the fourteenth signal;

(tt) forty-first means responsive to said twenty-eighth signal, said forty-first means being designed to manipulate the oxygen flow control means until there is no significant difference between the second signal and the fifteenth signal;

(uu) forty-second means responsive to said twenty-ninth signal, said forty-second means being designed to manipulate the helium-oxygen blend flow control means until there is no significant difference between the third signal and the sixteenth signal;

(vv) forty-third means responsive to said thirtieth signal, said forty-third means being designed to manipulate the temperature adjusting means until there is no significant difference between the forth signal and the seventeenth signal;

(ww) forty-forth means responsive to said thirty-first signal, said forty-forth means being designed to manipulate the temperature adjusting means until there is no significant difference between the fifth signal and the eighteenth signal;

(xx) forty-fifth means responsive to said thirty-second signal, said forty-fifth means being designed to manipulate the humidification adjusting means until there is no significant difference between the sixth signal and the nineteenth signal;

(yy) forty-sixth means responsive to said thirty-third signal, said forty-sixth means being designed to manipulate the temperature adjusting means until there is no significant difference between the seventh signal and the twentieth signal;

(zz) forty-seventh means responsive to said thirty-forth signal, said forty-third means designed to manipulate at least one of the following;

gaseous helium pressure control means, gaseous oxygen pressure control means, oxygen flow control means, helium flow control means, helium-oxygen blend flow control means, inspiratory gas volume control means and expiratory gas volume control means until there is no significant difference between the eighth signal and the twenty-first signal;

(aaa) forty-eighth means responsive to said thirty-fifth signal, said forty-eighth means designed to manipulate at least one of the following;

gaseous helium pressure control means, gaseous oxygen pressure control means, oxygen flow control means, helium flow control means, helium-oxygen blend flow control means, inspiratory gas volume control means and expiratory gas volume control means until there is no significant difference between the ninth signal and the twenty-second signal;

(bbb) forty-ninth means responsive to said thirty-sixth signal, said forty-ninth means being designed to manipulate at least one of the following;

gaseous helium pressure control means, gaseous oxygen pressure control means, oxygen flow control means, helium flow control means, helium-oxygen blend flow control means, inspiratory gas volume control means and expiratory gas volume control means until there is no significant difference between the tenth signal and the twenty-third signal;

(ccc) fiftieth means responsive to said thirty-seventh signal, said fiftieth means being designed to manipulate at least one of the following;

gaseous helium pressure control means, gaseous oxygen pressure control means, oxygen flow control means, helium flow control means, helium-oxygen blend flow control means, inspiratory gas volume control means and expiratory gas volume control means until there is no significant difference between the eleventh signal and the twenty-fourth signal;

(ddd) fifty-first means responsive to said thirty-eighth signal, said fifty-first means being designed to manipulate at least one of the following;

gaseous helium pressure control means, gaseous oxygen pressure control means, oxygen flow control means, helium flow control means, helium-oxygen blend flow control means, inspiratory gas volume control means and expiratory gas volume control means until there is no significant difference between the twelfth signal and the twenty-fifth signal; and

(eee) fifty-second means responsive to said thirty-ninth signal, said fifty-second means being designed to manipulate at least one of the following;

gaseous helium pressure control means, gaseous oxygen pressure control means, oxygen flow control means, helium flow control means, helium-oxygen blend flow control means, inspiratory gas volume control means and expiratory gas volume control means until there is no significant difference between the thirteenth signal and the twenty-sixth signal.