Abstract: Z maps combined with a standardized stimulus in the form of a targeted arterial partial pressures of carbon dioxide provide suprisingly enhanced images for the assessment of pathological CVR. For example, the z-map assessment of patients with known steno-occlusive diseases of the cervico-cerebral vasculature showed an enhanced resolution of the presence, localization, and severity of the pathological CVR. Z-map have been found to be useful to reduce the confounding effects of test-to-test, subject-to-subject, and platform-to-platform variability for comparison of CVR images showing the importance of combining this analysis with the standardized stimulus.

Abstract: Z maps combined with a standardized stimulus in the form of a targeted arterial partial pressures of carbon dioxide provide surprisingly enhanced images for the assessment of pathological CVR. For example, the z-map assessment of patients with known steno-occlusive diseases of the cervico-cerebral vasculature showed an enhanced resolution of the presence, localization, and severity of the pathological CVR. Z-map have been found to be useful to reduce the confounding effects of test-to-test, subject-to-subject, and platform-to-platform variability for comparison of CVR images showing the importance of combining this analysis with the standardized stimulus.

Abstract: Conventionally, the arterial input function is determined by administering a contrast agent and measuring the responsive magnetic signal in a reference voxel located in a large artery such as the middle cerebral artery. By instead measuring the signal in a voxel of the choroid plexus, a more accurate profile for the arterial input function may be obtained. The metabolic activity in the choroid plexus is negligible, which provides greater certainty for signal sampling.

Abstract: Deoxyhemoglobin in a subject may be modulated to act as a contrast agent for use in magnetic resonance imaging. Sequential gas delivery may be applied to adjust the level of deoxyhemoglobin in the subject. A suitable magnetic resonance imaging (MRI) pulse sequence that is sensitive to magnetic field inhomogeneities, such as a blood-oxygen-level dependent (BOLD) sequence, may be used to detect deoxyhemoglobin as a contrast agent.

Abstract: Alveolar dead space of a subject is determined by measuring an end tidal partial pressure of carbon dioxide during a sequence of normal breaths of the subject and, during a sequence of deep breaths by the subject, delivering a first volume of a first gas to the subject over a first portion of each inspiration by the subject. The first volume is less than or equal to an expected alveolar volume of the subject when the subject is breathing normally. A second volume of a second gas is delivered to the subject over a second portion of each inspiration. The second gas includes a neutral gas. An end tidal partial pressure of carbon dioxide is measured during the sequence of deep breaths. The alveolar dead space is computed using the end tidal partial pressures of carbon dioxide measured during the sequence of normal breaths and the sequence of deep breaths.

Abstract: A method of controlling a gas delivery apparatus including an apparatus controllable variable using an iterative algorithm to deliver a test gas (TG) for non-invasively determining a subject's pulmonary blood flow comprising iteratively generating and evaluating test values of a iterated variable based on an iterative algorithm in order output a test value of the iterated variable that meets a test criterion wherein iterative algorithm is characterized in that it defines a test mathematical relationship between the at least one apparatus controllable variable, the iterated variable and an end tidal concentration of test gas attained by setting the apparatus controllable variable, such that the iterative algorithm is determinative of whether iteration on the test value satisfies a test criterion or iteratively generates a progressively refined test value.

Abstract: An apparatus and method for controlling the end tidal partial pressure of a gas X in a subject's lung, and to the use of such an apparatus and method for research, diagnostic and therapeutic purposes, wherein the method consists of: -obtaining input of a series of logistically attainable PetX values for a series of respective breaths: -determining an amount of gas X required to be inspired by the subject in an inspired gas to target the PetX for each of said respective breaths; and controlling a gas delivery device to deliver the amount of gas in a volume of gas delivered to the subject in each of said respective breaths to target the respective PetX for that breath.

Abstract: An apparatus and method for controlling the end tidal partial pressure of a gas X in a subject's lung, and to the use of such an apparatus and method for research, diagnostic and therapeutic purposes, wherein the method consists of: —obtaining input of a series of logistically attainable PetX values for a series of respective breaths: —determining an amount of gas X required to be inspired by the subject in an inspired gas to target the PetX for each of said respective breaths: and—controlling a gas delivery device to deliver the amount of gas in a volume of gas delivered to the subject in each of said respective breaths to target the respective PetX for that breath.

Abstract: An apparatus and method for assessing vascular compliance in subjects with multiple sclerosis using sequential gas delivery is provided. The apparatus includes a gas delivery device and a processor. The processor controls the gas delivery device to deliver a first and second gas during a single inspiration. The first gas contains a mixture of oxygen and carbon dioxide necessary to target an end-tidal concentration of the two gases. The second gas includes a concentration of carbon dioxide equal to the target end-tidal concentration of carbon dioxide.

Abstract: A processor obtains input of a logistically attainable end tidal partial pressure of gas X (PetX[i]T) for one or more respective breaths [i] and input of a prospective computation of an amount of gas X required to be inspired by the subject in an inspired gas to target the PetX[i]T for a respective breath [i] using inputs required to utilize a mass balance relationship, wherein one or more values required to control the amount of gas X in a volume of gas delivered to the subject is output from an expression of the mass balance relationship. The mass balance relationship is expressed in a form which takes into account (prospectively), for a respective breath [i], the amount of gas X in the capillaries surrounding the alveoli and the amount of gas X in the alveoli, optionally based on a model of the lung which accounts for those sub-volumes of gas in the lung which substantially affect the alveolar gas X concentration affecting mass transfer.

Abstract: A system for detecting an abnormality in a subject's cerebrovascular response to a vasoactive stimulus in at least one region of interest (ROI) of the subject's brain The system comprises a system for generating the vasoactive stimulus (SVS), the SVS including a gas delivery device and a control system operable to deliver controlled amounts of carbon dioxide effective to attain at least one of a series of targeted increments or decrements in the subject's PetCO2, for a series of respective intervals; an imaging system comprising an MRI scanner for generating response signals corresponding to the subject's vasoactive response to the vasoactive stimulus; and a computer for analyzing the response signals, the computer including program code for computing at least one value representing a quantitative measure of the subject's cerebrovascular reactivity for the ROI, wherein the at least one value is obtained for a specific portion of the subject's vasoactive response in the ROI, the specific portion of the subject

Abstract: A method of controlling a gas delivery apparatus including an apparatus controllable variable using an iterative algorithm to deliver a test gas (TG) for non-invasively determining a subject's pulmonary blood flow comprising iteratively generating and evaluating test values of a iterated variable based on an iterative algorithm in order output a test value of the iterated variable that meets a test criterion wherein iterative algorithm is characterized in that it defines a test mathematical relationship between the at least one apparatus controllable variable, the iterated variable and an end tidal concentration of test gas attained by setting the apparatus controllable variable, such that the iterative algorithm is determinative of whether iteration on the test value satisfies a test criterion or iteratively generates a progressively refined test value.

Abstract: A method of controlling a gas delivery apparatus including an apparatus controllable variable using an iterative algorithm to deliver a test gas (TG) for non-invasively determining a subject's pulmonary blood flow comprising iteratively generating and evaluating test values of a iterated variable based on an iterative algorithm in order output a test value of the iterated variable that meets a test criterion wherein iterative algorithm is characterized in that it defines a test mathematical relationship between the at least one apparatus controllable variable, the iterated variable and an end tidal concentration of test gas attained by setting the apparatus controllable variable, such that the iterative algorithm is determinative of whether iteration on the test value satisfies a test criterion or iteratively generates a progressively refined test value.

Abstract: An anesthetic delivery system for use in conjunction with an anesthetic return system for reutilizing anesthetic exhaled by a subject, the system including a measurement system operatively connected to a breathing circuit for continuously measuring at least one flow parameter and anesthetic content of a gas stream reaching the subject and a control system for receiving input from the measurement system and controlling the amount of anesthetic entering the system, the control system including an input device for inputting a setting that corresponds to a desired amount of anesthetic in the gas stream reaching the subject, and utilizing a control algorithm for controlling the amount of anesthetic entering the system based on said desired amount of anesthetic, and flow and anesthetic content parameters as determined by the measurement system, such that the control algorithm is adapted to supplement anesthetic already in gas stream flowing to the subject to attain a level of anesthetic reaching the subject that co

Abstract: An apparatus and method for controlling the end tidal partial pressure of a gas X in a subject's lung, and to the use of such an apparatus and method for research, diagnostic and therapeutic purposes, wherein the method consists of: obtaining input of a series of logistically attainable PetX values for a series of respective breaths: determining an amount of gas X required to be inspired by the subject in an inspired gas to target the PetX for each of said respective breaths: and controlling a gas delivery device to deliver the amount of gas in a volume of gas delivered to the subject in each of said respective breaths to target the respective PetX for that breath.

Abstract: An electronic click wrench comprises a handle for applying torque through a shaft to a working head. The shaft includes torque sensing means for calculating the torque applied to a workpiece by the working head, and a trigger mechanism for sending a haptic feedback to a user by triggering a small movement of the handle relative to the working head when a set point torque is reached. The trigger mechanism comprises a permanent magnet that is normally anchored by magnetic attraction to a pole piece so as to resist separation when a force is applied through the handle, and an electromagnetic means actuable to reduce or cancel that magnetic attraction so as to permit separation of the pole piece and permanent magnet, thus generating the haptic feedback. Operation of the electromagnet may oppose the flux of the permanent magnet through the pole piece. Alternatively operation of the electromagnet may divert the flux of the permanent magnet away from the pole piece.

Abstract: A processor obtains input of a logistically attainable end tidal partial pressure of gas X (PetX[i]T) for one or more respective breaths [i] and input of a prospective computation of an amount of gas X required to be inspired by the subject in an inspired gas to target the PetX[i]T for a respective breath [i] using inputs required to utilize a mass balance relationship, wherein one or more values required to control the amount of gas X in a volume of gas delivered to the subject is output from an expression of the mass balance relationship. The mass balance relationship is expressed in a form which takes into account (prospectively), for a respective breath [i], the amount of gas X in the capillaries surrounding the alveoli and the amount of gas X in the alveoli, optionally based on a model of the lung which accounts for those sub-volumes of gas in the lung which substantially affect the alveolar gas X concentration affecting mass transfer.

Abstract: Z maps combined with a standardized stimulus in the form of a targeted arterial partial pressures of carbon dioxide provide suprisingly enhanced images for the assessment of pathological CVR. For example, the z-map assessment of patients with known steno-occlusive diseases of the cervico-cerebral vasculature showed an enhanced resolution of the presence, localization, and severity of the pathological CVR. Z-map have been found to be useful to reduce the confounding effects of test-to-test, subject-to-subject, and platform-to-platform variability for comparison of CVR images showing the importance of combining this analysis with the standardized stimulus.

Abstract: A breathing circuit for use in conjunction with a ventilator serving a mechanically-ventilated patient includes an expiratory gas airflow pathway; an inspiratory gas airflow pathway; and a gas mixing mechanism operable to mix inspiratory gas and expiratory gas in an amount sufficient to equilibrate the patient's PETCO2 and arterial PCO2 such that the patient's PETCO2 is a clinically reliable approximation of the patient's PaCO2.

Abstract: A method of controlling a gas delivery apparatus including an apparatus controllable variable using an iterative algorithm to deliver a test gas (TG) for non-invasively determining a subject's pulmonary blood flow comprising iteratively generating and evaluating test values of a iterated variable based on an iterative algorithm in order output a test value of the iterated variable that meets a test criterion wherein iterative algorithm is characterized in that it defines a test mathematical relationship between the at least one apparatus controllable variable, the iterated variable and an end tidal concentration of test gas attained by setting the apparatus controllable variable, such that the iterative algorithm is determinative of whether iteration on the test value satisfies a test criterion or iteratively generates a progressively refined test value.