Abstract:
Apparatus for the supply of breathable gas cyclically at an inspiratory pressure and the lower expiratory pressure substantially in synchronism with a patient's (16) respiration is disclosed. A flow generator (10) is coupled to a gas delivery system (12) to deliver the breathable gas to the patient's airways. A motor controller (23) receives a signal (36) representing respiratory flow. A motor controller (23) outputs a control signal (24) has control over the electric motor (25) and thus the turbine (22) to generate the required inspiratory and expiratory pressures. The controller (23) detects transitions between inspiration and expiration from the flow signal (36) to discriminate between patient inspiration and expiration. A counter (58) counts a first time duration commenced from the last transition to inspiration, whereby if the first time duration elapses before a transition to expiration, the controller (23) causes the supply of the expiration pressure. Furthermore, another counter (62) counts a second time duration commenced from the last transition to inspiration that forces the turbine (22) to supply the inspiratory pressure until the second time duration elapses even if during the second time duration there is a transition to expiration by the patient.
Abstract:
The pressure of breathable gas exiting a flow generator (10) is controlled by adjusting the efficiency of the flow generator. In one embodiment, a baffle plate (44) of a control element (40) can restrict the open entry area of a motor (16) driven turbine (18) of the flow generator. In another form, the degree of opening of the mouth of the flow generator inlet (20), and hence the pneumatic impedance, can be controlled, as in a similar manner can the impedance outlet (22).
Abstract:
The use of diagnostic processing of signals derived from a respiratory analysis mattress (2) to determine the occurence of central apneas is disclosed. A plurality of sensor strips (5) supply electrical signals arising from localised displacement by a patient's body. The individual body effort (displacement) signals are converted into digital form and provided to a processor (104). The occurence of a central apnea is determined by a relative dimunition of the digitised body effort signals. In one form, dimunition is determined by a reduction in amplitude in excess of a predetermined threshold amount. Alternatively, dimunition is determined by forming a ratio of a reference average movement effort value and a contemporaneous movement effort value, and comparing the ratio against a threshold reference value. Advantageously, a further condition can be that there is also a predominant cyclic signal within the range of respiratory origin present.
Abstract:
The occurrence of an arousal in a patient associated with an apneic or hypopneic episode can be determined. Sensors (10) are placed on a patient to obtain signals representative of at least two physiological variables, for example skin conductance, heart rate and blood oxygen concentration. The signals are conditioned by conditioning circuitry (12), then processed by a processor (18) to correlate at least two thereof. A coincident change in at least two of the processed signals is indicative of the occurrence of an arousal, that in turn indicates an apneic or hypopneic episode has occurred. A patient thus can be diagnosed as suffering conditions such as obstructive sleep apnea.
Abstract:
A pair of nasal prongs (15), suitable for insertion into the lower portion of the nares, join together via a small plenum chamber (16) to form a single tube (17) conveying the nasal pressure towards an electrical pressure transducer (19). Another prong (20) is held in proximity with the patient's mouth. A baffle element (25) extends downwards from a location above the open end of the prong (20) to redirect a portion of oral airflow. The oral tube (21) extends towards the electrical pressure transducer (19), and conjoins with the nasal tube (17) at a junction (22) to form a common tube (18) connected to the pressure transducer (19). The relative lengths and/or diameters of the nasal tube (17) and the oral tube (21) are arranged so that the respective pneumatic impedances are different, so that the contributions of respiratory airflow from each of said tubes (17, 21) are substantially equal.
Abstract:
A method for analysing an electro-encephalogram (EEG) and apparatus for implementing the method are described. Preferably EEG's from the left and right sides of the head are analysed together. An EEG is analysed by detecting the bursts of activity having amplitudes which exceed a threshold voltage and each burst of activity in the EEG is determined to have ended when it is followed by a quiescent period below the threshold voltage having a duration of, say, at least 6 seconds. The total time of all quiescent periods occurring within an epoch, for example, 10 minutes is then calculated and displayed. The apparatus may include a digital computer for effecting statistical analysis of the total times for many consecutive epochs. The computer may also be used in generating the total times. A graphical output representing the total times may be produced enabling the progress of a patient to be assessed rapidly.
Abstract:
Apparatus (40) for monitoring oro-nasal respiratory flow is disclosed. The apparatus (40) is formed of a curved plate (42) to which is substantially perpendicularly arranged a planar member (44), the plate (42) and the member (44) are connected by a neck portion (46). Mounted in an upstanding fashion from the planar member (44) are two nasal prongs (48, 50). Two PVDF sensors (60) are mounted from, and lie in, the plane of the planar member (44), co-operating with a respective nasal prong (48, 50). A further PVDF sensor (80) in planar form is arranged to be downwardly directed and perpendicular to the planar member (44) so as to be located in the vicinity of the mouth when the apparatus (40) is being worn by a patient. The PVDF sensors (60, 80) deflect respectively under the influence of nasal and oral airflow, and generate electrical charge having a determined relationship with the airflow.
Abstract:
An external fixator for use in the treatment of bone fractures comprises a pair of rigid body member 1a and 1b, each of the body members being provided with a plurality of mountings (24) for holding bone pins (25) securely relative to the associated body member after the bone pins have been inserted into a bone part, the body members being so interconnected as to permit only rectilinear relative movement between them, means (12) for applying, in use, a substantially constant force tending to urge the body members towards each other and means (19) for temporarily increasing the applied force above the constant value.