Method and apparatus for conducting xenon inhalation studies
First Claim
1. Apparatus for conducting xenon-enhanced inhalation of a patient'"'"'s lungs during neurological studies, including an oxygen source, a xenon source, and a patient breathing mask for transmitting inhalation gas to said patient, the improvement comprising:
- a flexible bag defining a variable volume chamber for receiving said inhalation gas, said bag having an inhalation port and an exhalation port;
conduit means interconnected to said inhalation port, said patient breathing mask, and said exhalation port for series connecting said variable volume chamber and said patient'"'"'s lungs in a closed loop;
a gas discharge port in fluid communication with said conduit means for releasing gas from said closed loop;
oxygen sampling means in fluid communication with said conduit means for detecting oxygen concentration within said closed loop;
xenon sampling means in fluid communication with said conduit means for detecting xenon concentration within said closed loop;
control means for providing preselected oxygen and xenon concentration values;
oxygen input valve means in fluid communication with said conduit means for selectively inputting oxygen from said oxygen source to said closed loop in response to a detected oxygen concentration value from said oxygen sampling means less than said preselected oxygen concentration value from said control means;
xenon input valve means in fluid communication with said conduit means for selectively inputting xenon from said xenon source to said closed loop to response to a detected xenon concentration value from said xenon sampling means less than said preselected xenon concentration value from said control means;
carbon dioxide removal means in fluid communication with said conduit means for removing carbon dioxide from said inhalation gas within said closed loop;
volume indicator means for detecting when said variable volume chamber obtains a predetermined minimum volume; and
first valve means responsive to said volume indicator means for closing said gas discharge port and terminating gas discharge from said closed loop when said variable volume chamber obtains said predetermined minimum value;
wherein substantially all xenon gas is thereafter repeatedly exhaled from said patient'"'"'s lungs to said flexible bag and retained within said closed loop.
1 Assignment
0 Petitions
Accused Products
Abstract
Inhalation methods and apparatus are provided for performing xenon-enhanced studies or tests. The present invention is useful during computed tomography studies to provide neurologists with accurate yet relatively inexpensive measurements of cerebral blood flow. The apparatus includes a variable volume xenon/oxygen chamber for obtaining a closed-loop arrangement with the patient, thereby minimizing xenon gas usage during the study. According to the method of the invention, the volume of the xenon/oxygen chamber is reduced during a first phase of the study, while the patient'"'"'s lung xenon concentration increases. The second phase is initiated when the variable chamber obtains a selected minimum value, after which exhalation returns to the chamber. During the second phase, oxygen and xenon are added to the closed loop system to maintain the desired concentrations, carbon dioxide is removed, and the chamber volume slowly increases. Apart from xenon inhalation studies, the method and apparatus have utility for a wide range of inhalation procedures, especially those involving relatively expensive inhalation gases.
-
Citations
29 Claims
-
1. Apparatus for conducting xenon-enhanced inhalation of a patient'"'"'s lungs during neurological studies, including an oxygen source, a xenon source, and a patient breathing mask for transmitting inhalation gas to said patient, the improvement comprising:
-
a flexible bag defining a variable volume chamber for receiving said inhalation gas, said bag having an inhalation port and an exhalation port; conduit means interconnected to said inhalation port, said patient breathing mask, and said exhalation port for series connecting said variable volume chamber and said patient'"'"'s lungs in a closed loop; a gas discharge port in fluid communication with said conduit means for releasing gas from said closed loop; oxygen sampling means in fluid communication with said conduit means for detecting oxygen concentration within said closed loop; xenon sampling means in fluid communication with said conduit means for detecting xenon concentration within said closed loop; control means for providing preselected oxygen and xenon concentration values; oxygen input valve means in fluid communication with said conduit means for selectively inputting oxygen from said oxygen source to said closed loop in response to a detected oxygen concentration value from said oxygen sampling means less than said preselected oxygen concentration value from said control means; xenon input valve means in fluid communication with said conduit means for selectively inputting xenon from said xenon source to said closed loop to response to a detected xenon concentration value from said xenon sampling means less than said preselected xenon concentration value from said control means; carbon dioxide removal means in fluid communication with said conduit means for removing carbon dioxide from said inhalation gas within said closed loop; volume indicator means for detecting when said variable volume chamber obtains a predetermined minimum volume; and first valve means responsive to said volume indicator means for closing said gas discharge port and terminating gas discharge from said closed loop when said variable volume chamber obtains said predetermined minimum value; wherein substantially all xenon gas is thereafter repeatedly exhaled from said patient'"'"'s lungs to said flexible bag and retained within said closed loop. - View Dependent Claims (2, 3, 4, 5, 6, 7)
-
-
8. The method of conducting enhanced gas inhalation of a patient, comprising:
-
inputting an initial volume of gas having a desired enhanced-gas concentration to a mixture of oxygen with a variable volume chamber; forming a closed loop between said variable volume chamber and said patient; detecting oxygen concentration in said closed loop; detecting enhanced gas concentration in said closed loop; inputting oxygen to said closed loop in response to said detected oxygen concentration to maintain a desired oxygen concentration; inputting enhanced gas to said closed loop in response to said detected enhanced gas concentration to maintain a desired enhanced gas concentration; removing carbon dioxide from said gas within said closed loop; discharging said gas having said desired enhanced-gas concentration from said variable volume chamber to said patient; releasing exhalation gas from said closed loop while reducing the volume of said variable volume chabmer during a first time period sufficient to substantially increase the enhanced gas concentration of said exhalation gas; generating a first signal indicative of said variable chamber obtaining a selected minimum volume; and thereafter terminating release of said exhalation gas from said closed loop in response to said first signal and recirculating gas within said closed loop while adding enhanced gas to said closed loop in response to said detected enhanced gas concentration and increasing the volume of said variable volume chamber. - View Dependent Claims (9, 10, 11, 12, 13, 14)
-
-
15. Apparatus for conducting enhanced gas inhalation of a patient, comprising:
-
an oxygen source; an enhanced gas source; a flexible bag defining a variable volume chamber for receiving said inhalation gas; conduit means for series interconnecting said variable volume chamber and said patient in a closed loop; a gas discharge port in fluid communication with said conduit means for releasing gas from said closed loop; oxygen sampling means in fluid communication with said conduit means for detecting oxygen concentration within said closed loop; enhanced gas sampling means in fluid communication with said conduit means for detecting enhanced gas concentration within said closed loop; control means for providing preselected oxygen and enhanced gas concentration values; oxygen input valve means in fluid communication with said conduit means for selectively inputting oxygen from said oxygen source to said closed loop in response to a detected oxygen concentration value from said oxygen sampling means less than said preselected oxygen concentration value from said control means; enhanced gas input valve means in fluid communication with said conduit means for selectively inputting enhanced gas from said enhanced gas source to said closed loop in response to a detected enhanced gas concentration value from said enhanced gas sampling means less than said preselected enhanced gas concentration value from said control means; carbon dioxide removal means in fluid communication with said conduit means for removing carbon dioxide from said closed loop; volume indicator means for detecting when said variable volume chamber obtains a predetermined minimum volume; and first valve means responsive to said volume indicator means for closing said gas discharge port and terminating gas discharge from said closed loop when said variable valve chamber obtains said predetermined minimum value. - View Dependent Claims (16, 17, 18, 19, 20)
-
-
21. The method of conducting enhanced gas inhalation of a patient, comprising:
-
inputting an initial volume of gas having a mixture of oxygen with a desired enhanced-gas concentration to a variable volume chamber; forming a closed loop between said variable volume chamber and said patient; detecting oxygen concentration in said closed loop; detecting enhanced gas concentration in said closed loop; inputting oxygen to said closed loop in response to said detected oxygen concentration to maintain a desired oxygen concentration; inputting enhanced gas to said closed loop in response to said detected enhanced gas concentration to maintain a desired enhanced gas concentration; removing carbon dioxide from said gas within said closed loop; generating an initial volume signal indicative of said variable volume chamber obtaining said initial volume of a selected value; initiating discharge of said gas having said enhanced-gas concentration from said variable volume chamber to said patient in response to said initial volume signal; releasing exhalation gas from said closed loop while reducing the volume of said variable volume chamber during a first time period sufficient to substantially increase the enhanced gas concentration of said exhalation gas; thereafter terminating release of said exhalation gas from said closed loop and recirculating gas within said closed loop while adding enhanced gas to said closed loop in response to said detected enhanced gas concentration and increasing the volume of said variable volume chamber. - View Dependent Claims (22, 23, 24)
-
-
25. Apparatus for conducting enhanced gas inhalation of a patient, comprising:
-
an oxygen source; an enhanced gas source; a flexible bag defining a variable volume chamber for receiving said inhalation gas; conduit means for series interconnecting said variable volume chamber and said patient in a closed loop; a gas discharge port in fluid communication with said conduit means for releasing gas from said closed loop; oxygen sampling means in fluid communication with said conduit means for detecting oxygen concentration within said closed loop; enhanced gas sampling means in fluid communication with said conduit means for detecting enhanced gas concentration within said closed loop; control means for providing preselected oxygen and enhanced gas concentration values; oxygen input valve means in fluid communication with said conduit means for selectively inputting oxygen from said oxygen source to said closed loop in response to a detected oxygen concentration value from said oxygen sampling means less than said preselected oxygen concentration value from said control means; enhanced gas input valve means in fluid communication with said conduit means for selectively inputting enhanced gas from said enhanced gas source to said closed loop in response to a detected enhanced gas concentration value from said enhanced gas sampling means less than said preselected enhance gas concentration value from said control means; carbon dioxide removal means in fluid communication with said conduit means for removing carbon dioxide from said closed loop; volume indicator means for detecting when said variable volume chamber obtains an initial volume of a selected value; valve means responsive to the detection of said selected value by the volume indicator means for automatically opening to initiate fluid communication between said flexible bag and said patient. - View Dependent Claims (26, 27, 28, 29)
-
Specification