Abstract:
A ventilator for respiratory care, intended for connection to a patient, avoids needless alarms, caused by a patient&#39;s attempts to speak and needless suffering because of the patient&#39;s inability to trigger an alarm, by having a sound detector arranged to detect and identify sounds made by the patient, preferably intentionally. A control unit is operatively connected to the sound detector acts on at least one function in the ventilator on the basis of sounds identified by the sound detector.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention is directed to a ventilator of the type having a tube adapted for communication with a patient&#39;s airways for exchanging gas with the patient in an inspiration phase and an expiration phase of a breathing cycle.  
           [0003]    2. Description of the Prior Art  
           [0004]    In respiratory care, particularly when a tracheal tube is used for connecting a patient to the ventilator, the patient sometimes finds it hard to communicate with others. Even if the patient succeeds in speaking some words, the ventilator often interprets this as a difference between the volume of inspired and expired breathing gas. This triggers an alarm that effectively drowns out any words spoken by the patient.  
           [0005]    Corresponding problems can arise with ventilators with limited adaptability or inappropriate settings for the respiratory treatment. If the patient attempts to communicate the discomfort of struggling against the ventilator, this might not be noticed by anyone. When a staff member finally arrives (e.g. because a volume alarm is sounded), the patient may not be able to reveal her/his discomfort. No alarm might be triggered if the influence of the volumes is less pronounced.  
           [0006]    Another problem exists with regard to patients who are conscious but too weak (or paralyzed) to be able to use the alarm button to attract the staff&#39;s attention. Therefore, these patients may experience pain or general discomfort without being able to summon help.  
         SUMMARY OF THE INVENTION  
         [0007]    An object of the present invention is to provide a ventilator that solves the aforementioned problems, at least in part.  
           [0008]    The above object is achieved in accordance with the principles of the present invention in a ventilator for respiratory care having a tube adapted for connection to a patient, and having a sound detector which detects and identifies sounds made by the patient, and a control unit operatively connected to the sound detector for influencing at least one function in the ventilator on the basis of sounds from the patient identified by the sound detector.  
           [0009]    One or a number of new special functions can be added and performed by the ventilator with the use of a sound detector devised to detect sounds made by the patient, especially when the detected sounds can be interpreted as having been intentionally made by the patient.  
           [0010]    Needless alarms (which would otherwise prevent the patient&#39;s voice from being heard) in particular can be inhibited and necessary alarms generated (e.g. summoning staff with an optical signal or some form of remote signal). The latter is especially advantageous when the patient makes unintentional sounds caused by e.g. pain.  
           [0011]    Inhibition of alarms can be limited to certain types of discrepancies, e.g. a difference between inspired and expired volumes, and even limited to a certain sound magnitude, e.g. with specific upper and lower limits.  
           [0012]    Other functions in the ventilator that could be affected on the basis of sounds from the patient are the volume of gas delivered in inspiratory phases (increase/decrease), the duration of inspiratory and expiratory phases (shorter/longer), changes in the respiratory mode (from controlled respiration to assisted respiration, from assisted respiration to spontaneous respiration or between different kinds of controlled, supported and spontaneous respiration).  
       
    
    
     DESCRIPTION OF THE DRAWINGS  
       [0013]    [0013]FIG. 1 shows a first embodiment of a ventilator according to the invention.  
         [0014]    [0014]FIGS. 2 and 3 show alternative placements for a sensor means for detecting sound waves in the inventive ventilator.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0015]    One embodiment of a ventilator  2  according to the invention is shown in FIG. 1. In this context, the term “ventilator” refers to all devices capable of providing respiratory assistance, i.e. respirators (high end and low end), resuscitators and anaesthetic machines are all regarded as ventilators in this context.  
         [0016]    The ventilator  2  is connected to a patient  4  in order to provide some form of respiratory support. The ventilator  2  has an inspiratory line  6 , a Y-piece  8 , a tracheal tube  10  and an expiratory line  12 . Other configurations for connecting components are possible.  
         [0017]    A breathing gas can be prepared from gases delivered to the ventilator  2  through a first gas connection  14 A and a second gas connection  14 B. The gas is prepared in a mixer section  16  which contains e.g. valves etc. according to known prior art machines.  
         [0018]    At the inspiratory side, the breathing gas passes a first flow meter  18  and a first manometer  20 . These components can be integrated with the mixer section  16 .  
         [0019]    At the expiratory side, the breathing gas passes a second flow meter  22  and a second manometer  24  before the breathing gas is discharged through an expiratory valve  26 .  
         [0020]    All the functions in the ventilator are regulated by a control unit  28 . The control unit  28  receives measurement signals from the available sensors and sends control signals to regulated components, e.g. in the mixer section  16 . As known from prior art systems, the control unit  28  can include one or several processors, ROM, RAM, PROM, etc. the control unit  28  need further not be one single unit, but can be diversified into several smaller units with specialized functions.  
         [0021]    The control unit  28  also includes an alarm unit  30 . The alarm unit  30  can monitor a number of functions in the ventilator  2  and the patient  4 . An alarm is generated when a fault occurs. An indication displayed on a screen (not shown in FIG. 1) is sufficient for some types of alarms, but an acoustic alarm should be sounded for most alarms. The alarm is sounded by a speaker  32 .  
         [0022]    The ventilator described thus far (with certain modifications) could be formed by virtually any known medical breathing apparatus.  
         [0023]    A distinguishing feature of the ventilator according to the invention, which can be added to or designed into any known breathing apparatus, is a sound sensor  34  for detecting sounds and a sound analyzer  36  for identifying the voice of the patient  4  or sounds made by the patient  4  (preferably intentionally). The sound sensor  34  and the sound analyzer  36  jointly constitute a sound detector for detecting and identifying sounds.  
         [0024]    The sound analyzer  36  is connected to the control unit  28  in order to perform sound analyses. The control unit  26  is modified to influence at least one function in the ventilator  2  based on the sounds made by the patient  4 .  
         [0025]    One possible function is for the sound analyzer&#39;s  36  identification of groans or corresponding sounds indicating that the patient is feeling pain or discomfort. The control unit  28  can then control the alarm unit  30  to generate an alarm for summoning staff.  
         [0026]    The volume alarm is another alarm-related function that can be actuated. Most ventilators  2  monitor the volume of inspired and expired breathing gas. An alarm is generated when the discrepancy between these two volumes becomes excessive. This is because the cause may be leakage or some other defect requiring attention. However, the patient may be causing the discrepancy by expelling gas around the sides of the tracheal tube  10  to enable her/him to speak. No alarm is desirable in this situation, and if this fault arises at the same time as the patient speaks (as identified by the sound analyzer&#39;s  36 ), the control unit  28  can act on the alarm unit  30  to prevent the triggering of an alarm. Such an event should be logged (registered) to give the staff a better picture of the condition of the patient  4  and the operation and function of the ventilator  2 .  
         [0027]    In addition to inhibiting an alarm, the control unit  28  also can regulate the mixer section  16  and the expiratory valve  26  so gas flows during inspiration and expiration are adapted to (and facilitate) the attempts at speaking by the patient  4 . Alternately, or as a complement, the control unit  28  can control the duration of inspiration and/or expiration.  
         [0028]    The sound sensor  34  in the embodiment according to FIG. 1 is arranged near the patient  4  (on the exterior of the Y-piece  10 ). Other placements are possible. For example, FIG. 2 shows a tracheal tube  38  with a sound sensor  40  at the exterior thereof arranged and connectable by a signal line  42  to the sound analyzer  36 .  
         [0029]    [0029]FIG. 3, which depicts a Y-piece  44 , shows another example of an alternative location. A sound sensor  46  is arranged inside the Y piece  44  and is connected by a signal line  48  to the sound analyzer  36 .  
         [0030]    Other placements are immediately evident, such as on the patient (especially on her/his neck, near the vocal cords), etc.  
         [0031]    The sound sensor can be a microphone, pressure-sensitive sensor, vibration-sensitive sensor or any kind of known sound-detecting sensor, depending on its placement.  
         [0032]    As shown in FIG. 1, the sound analyzer  36  can be provided with a memory  50  to facilitate identification of sounds made by a patient  4 . In an initial stage, samples of the voice of the patient  4  are stored in the memory  50 . Sound subsequently detected by the sound sensor  34  can then be compared (spectrally or in some other way) to the stored sound. The sound analyzer  36  can advantageously include or be a frequency analyzer for analysis of the frequencies in the detected sound. Sounds from the patient  4  can then be identified from this analysis.  
         [0033]    Although modifications and changes may be suggested by those skilled in the art, it is the intention of the inventors to embody within the patent warranted hereon all changes and modifications as reasonably and properly come within the scope of their contribution to the art.