Abstract:
Systems and methods are provided for inserting an endoscope through an anatomical cavity to a target site. A speaker is positioned externally proximate to a patient and the endoscope is inserted into the anatomical cavity. A signal is received from at least one sensor positioned near the distal end of the endoscope. The signal is indicative of vibrations induced in internal cavity tissue by the externally positioned speaker. A first anatomical structure in contact with the distal end of the endoscope is identified based on the signal indicative of vibrations induced in the internal cavity tissue by the externally positioned speaker. As the distal end of the endoscope moves from the first anatomical structure into contact with other anatomical structures along a path to the target site, the received signal indicative of induced vibrations changes correspondingly and is used to guide the endoscope to the target site.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Patent Application No. 62/066,020, filed Oct. 20, 2014, and entitled “INTUBATION WITH AUDIOVIBRATORY GUIDANCE,” the entire contents of which are incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    The present invention relates to systems and methods for placement of a flexible breathing tube into the trachea to maintain an open airway and/or to serve as a conduit through with to administer certain medical therapies (e.g., drugs)—also known as tracheal intubation. 
       SUMMARY 
       [0003]    With nearly 25 million intubations performed each year in the U.S., and roughly 2% ending in failure, there is a need, with that many lives at stake, for improved technology. Various systems and methods described herein provide robotic-based solutions that intubate persons with greater accuracy than is humanly possible and thereby reduces or eliminates the number of failures and other problems in airway management. Furthermore, by being autonomously controlled, the systems can be used by first responders and military personnel for medical emergencies thereby saving additional lives outside the operating room. 
         [0004]    In one embodiment, the invention provides an endoscope-type robotic device that is propelled by an electric motor. The motor is controlled by a computer-based controller that receives information about the location of the tip of the endoscope through signals from various sensors—including one or more magnetometers and one or more accelerometers—located near the tip of the endoscope. These sensors generate signals that are responsive to a transponder (i.e., a small loudspeaker) positioned on the subject&#39;s neck near the Adam&#39;s apple. Vibrations caused by sound waves from the loudspeaker are conducted at varying amplitudes by different anatomical structures. These vibrations are detected by the accelerometer and monitors by the controller. The magnetometers monitor a magnetic field generated by a magnet of the loudspeaker (or, in some constructions, a separate permanent or electro-magnet). The controller controls the insertion and turning direction of the endoscope based on the monitored vibrations and magnetic field. Once the tip of the endoscope has passed through the vocal folds (i.e., the vocal chords) and into the larynx, the endoscope becomes a mechanical guide for an endotracheal tube that is inserted around the endoscope to complete intubation. 
         [0005]    In some embodiments, the invention provides a method of robotically guided intubation. A loudspeaker is positioned proximal to the neck of a subject and activated to generate audio vibration of the anatomic structures. A controller causes a motor to advance a controlled endoscope into the airway of the subject. The controller receives a signal from an accelerometer positioned at a distal end of the endoscope and compares the signal to a threshold. When the signal exceeds a first threshold, the controller determines that the distal end of the endoscope is in contact with the epiglottis of the subject and controllably turns the distal end of the endoscope downward. When the signal subsequently exceeds a second, higher threshold, then the controller determines that the distal end of the endoscope is in contact with the laryngeal inlet. The controller then stops insertion of the endoscope. 
         [0006]    In some such embodiments, a flexible tube is then extended around the endoscope and inserted through the trachea to the larynx of the subject. In some embodiments, the loudspeaker includes a magnet that generates a magnetic field. The controller continually monitors a signal from a magnetometer positioned in the distal end of the endoscope to determine whether the endoscope tip is centered and, if not, the controller moves the tip of the endoscope laterally. 
         [0007]    In some embodiment, the controller monitors whether the signal from the accelerometer falls below the first threshold after contact with the epiglottis is detected. When the signal from the accelerometer falls below the first threshold, the controller determines that contact between the distal tip of the endoscope and the epiglottis has been lost and controllably turns the distal end of the endoscope downward until contact between the distal tip of the endoscope and the epiglottis is reestablished (i.e., the signal from the accelerometer again exceeds the first threshold). 
         [0008]    Other aspects of the invention will become apparent by consideration of the detailed description and accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]      FIG. 1  is a block diagram of an autonomous robotic intubation system according to one embodiment. 
           [0010]      FIG. 2  is a perspective view of an external transducer of the system of  FIG. 1 . 
           [0011]      FIG. 3  is a perspective view of two endoscopes of the system of  FIG. 1  and an intubation tube. 
           [0012]      FIG. 4  is a perspective view of an auger-type tip for the endoscope in one embodiment of the system of  FIG. 1 . 
           [0013]      FIG. 5A  is a perspective view of an insertion motor mask of the system of  FIG. 1 . 
           [0014]      FIG. 5B  is a close-up view of the insertion mechanism of the insertion motor mask of  FIG. 5A . 
           [0015]      FIG. 6A  is a perspective view of the lateral movement drive mechanism for the endoscope of the system of  FIG. 1 . 
           [0016]      FIG. 6B  is a close-up view of the controllable tip of the endoscope of the system of  FIG. 1  that is driven by the drive mechanism of  FIG. 6A . 
           [0017]      FIG. 7  is a perspective view of an example of a handheld endoscope insertion control system according to  FIG. 1 . 
           [0018]      FIG. 8  is a cross-sectional view of a human airway. 
           [0019]      FIG. 9  is a graph of the output of an acceleration sensor in contact with various anatomic structures in response to audiovibratory stimulus generated by the loudspeaker of the system of  FIG. 1 . 
           [0020]      FIG. 10  is a graph of the output of the magnetic field sensor of the system of  FIG. 1  at various locations in response to the magnetic field generated by the loudspeaker of the system of  FIG. 1 . 
           [0021]      FIG. 11  is a three-dimensional graph of the magnetic field generated by the loudspeaker of the system of  FIG. 1 . 
           [0022]      FIG. 12  is a flowchart of a method of controlled insertion of the robotic endoscope device of  FIG. 1  for autonomous robotic intubation. 
       
    
    
     DETAILED DESCRIPTION 
       [0023]    Before any embodiments of the invention are explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. 
         [0024]    Successful intubation on a trauma patient requires the placement of an endotracheal tube within the trachea to facilitate external oxygen delivery. Navigating the endotracheal tube is a skill learned through intensive training and only mastered with experience. When dealing with robotic navigation through biological systems, rapidly changing and unique environments must be accounted for. The systems and methods described below utilize magnetic localizing to place an absolute reference of the tip of an endoscopic robot inserted through the trachea of a patient. Sonic excitation is also used to identify key biological landmarks that will guide the insertion process. 
         [0025]      FIG. 1  illustrates an example of a system  100  that takes advantage of audio conductivity of various anatomical structures to autonomously guide an endoscopic robot to facilitate the intubation process. A controller  101  includes a processor  102  and memory  103 . In this example, the memory  103  is a non-transient, physical computer-readable memory device such as, for example, one or more flash memory modules or a hard drive. In other embodiments, the memory  103  may be replaced with other non-transient, physical computer-readable memory devices such as, for example, RAM or ROM. The memory  103  stores instructions that are executed by the processor  102  to control the operation of the system  100 . 
         [0026]    The controller  101  receives output signals from a number of sensors positioned at the distal end of an endoscope  105 . These sensors include a magnetometer  107  that detects magnetic fields acting on the distal tip of the endoscope and an accelerometer  109  that is configured to detect vibrations. In some constructions, a gyroscopic sensor is positioned at the distal end of the endoscope in addition to or instead of the accelerometer and/or the magnetometer. The controller  101  provides output signals to control the operation of a loudspeaker  111 . The loudspeaker in this example includes a magnet  113  and an audio output  115 . The controller  101  also provides output signals to provide robotic control  117  of the robotic endoscope. In particular, the controller  101  controls an insertion motor  119  that advances the endoscope into the anatomy and a turning motor  121  that controls lateral movement of the endoscope tip and provides for steering of the endoscope tip. 
         [0027]      FIG. 2  illustrates an example of the loudspeaker  111  that acts as a transducer which causes vibration of anatomical structures of the patient. In this example, the loudspeaker  111  is a 100 hz speaker with a 1 inch diameter that is capable of battery-powered operation. However, in other constructions, speakers of other sizes and operating characteristics may be used. As described in detail below, this audiovibratory response allows the controller to detect contact with specific anatomical structures as the endoscope is inserted towards the larynx. In the example of  FIG. 2 , the loudspeaker  111  is coupled to the controller by an audio cable  201 . However, in other implementations, the loudspeaker  111  may or may not require a wired audio cable. 
         [0028]      FIG. 3  illustrates the tip of the endoscope  105  in further detail. As noted above, the endoscope tip is equipped with an accelerometer  109  that produces a signal responsive to vibrations caused by the loudspeaker  111  and a magnetometer  107  that produces a signal indicative of a magnetic field acting upon the distal tip of the endoscope. This endoscope is capable of 6 Degree-of-Freedom (DOF) control using both vibration and magnetic tracking.  FIG. 3  also illustrates an alternative construction of the endoscope tip  105  where the tip is equipped with an acceleration sensor  109 . However, instead of positioning a magnetometer in the distal tip of the endoscope  105 A, a permanent magnet  301  is positioned to generate a magnetic field internally. In such constructions, a magnetic field sensor/magnetometer is placed external to the patient to monitor absolute location of the distal tip of the endoscope  105 A. In still other constructions, the system can provide one DOF control by omitting the magnetic sensor and operating based only on vibratory tracking. 
         [0029]      FIG. 3  also illustrates a flexible plastic intubation tube  303 . As described further below, after insertion of the endoscope is complete, the proximal end of the endoscope can be placed inside of the intubation tube  303  so that the intubation tube  303  can be rapidly inserted to the larynx. The endoscope is then removed leaving only the properly placed intubation tube  303 . Alternatively, the intubation tube  303  can be placed around the endoscope before insertion begins such that the intubation tube  303  is inserted along with the endoscope. 
         [0030]    As illustrated in  FIG. 4 , the distal tip of the endoscope  309  may be equipped with a soft auger  311 . The soft material of the auger  311  minimizes trauma that might otherwise occur when the endoscope comes into contact with tissue within the oral cavity and airway. The spiral (e.g., “screw”) shape of the auger  311  also helps pull the endoscope forward should it become obstructed or stuck against a fleshy part of the oral cavity and airway. Thus, it is possible to move the endoscope forward with a combined push force (provided by the external actuator (described below)) and pull force (provided by rotation of the auger  311 ). 
         [0031]      FIG. 5A  illustrates a motorized insertion mask  400  that is placed over the mouth of a patient to control advancement of the endoscope through the trachea. The mask  400  includes a patient contact rest  401  that is placed in contact with the patient&#39;s face and provides stabilized support for the insertion device  400 . The motor  119  causes opposite rotation of two pinch rollers  403  that push the endoscope forward or backward.  FIG. 5B  shows the insertion rollers  403 A and  403 B in further detail. As shown in  FIG. 5B , the motor  119  is coupled to both the first roller  403 A and the second roller  403 B by a series of gears or belts  405 . As the first roller  403 A moves in a clockwise fashion, the second roller  403 B moves counterclockwise to push the endoscope through an opening  407  in the mask. 
         [0032]      FIG. 6A  illustrates an example of a drive mechanism  121  that controls lateral movement of the distal tip of the endoscope  105 .  FIG. 6B  shows the controllable tip of the endoscope  105  in further detail. The drive mechanism  121  is capable of steering the distal tip of the endoscope  105  in any radial direction (i.e., up, down, left, and right). 
         [0033]      FIG. 7  illustrates another example of a device  700  for advancing an endoscope into the oral cavity of a patient. In the handheld device of  FIG. 7 , a handle portion  701  is coupled to a patient mask  703  by a curved body  705 . The patient mask  703  is constructed of a soft plastic material and is designed to rest against the face of the patient as the endoscope is inserted orally. An electronic motor  707  is positioned near the mask  703  on the curved body  705  and drives a pair of pinch rollers  709  (as discussed above) to advance an endoscope  711 A &amp;  711 B into the oral cavity of the patient. Excess length of the endoscope  711 B is drawn from a proximal side of the pinch roller  709  as the endoscope  711 A is extended into the oral cavity of the patient. 
         [0034]    During use, an operator holds the device  700  by the handle portion  701  and inserts a fixed endoscope stage  713  into the mouth of the patient until the mask  703  rests against the patient&#39;s face. The operator then activates a control  715  positioned on the handle portion  701  which causes the motor  707  to advance the endoscope  711 A from the fixed endoscope stage  713  and into the airway of the patient. At the same time, a rotational mechanism mounted inside the handle portion  701  rotates the endoscope  711 B. Rotation of the endoscope  711 B causes corresponding rotation of a soft auger  717  positioned on the distal tip of the endoscope  711 B. Rotation of the soft auger  717  pulls the endoscope  711 A into the airway of the patient for a combined push and pull force. 
         [0035]    In the example of  FIG. 7 , the controller is housed within the handle portion  701  and coupled to the motor  707  by one or more cables  719 . Although these cables  719  are shown as exposed in the example of  FIG. 7 , in other implementations, the cables  719  may be housed within the curved body  705  of the device  700 . 
         [0036]      FIG. 8  illustrates the anatomical pathway that the endoscope must follow during the intubation process. The tube is inserted through the mouth of the patient to the back of the oral cavity where the epiglottis is located. At the posterior of the epiglottis, the tube must be directed downward until it reaches the laryngeal hood. The tube is then moved forward to enter through the vocal folds and into the larynx. 
         [0037]    The vibratory conductivity of these various anatomical structures varies. The epiglottis will sympathetically vibrate in response to a moving magnetic coil. When the transducer  111  vibrating at 100 Hz is placed anterolateral to the thyroid cartilage, a bridge is formed via the thyroid cartilage and epiglottis cartilage attachment. This close coupling allows for more efficient transfer of excitation frequency to the epiglottis than to the surrounding tissue. 
         [0038]      FIG. 9  illustrates the relative output signal of the accelerometer when the distal tip of the endoscope is in contact with various different anatomical structures. Contact with the epiglottis is shown to have a marked increase in the accelerometers response relative to a distal tip located in the mouth, resting on the tongue, or positioned near, but not in contact with, the epiglottis. Due to this difference in signal conduction between soft tissue, cartilage, and the airway in close proximity to the transducer, the output signal of the accelerometer can be monitored to maintain contact with the posterior of the epiglottis and to guide the endotracheal tube towards the larynx for insertion into the vocal folds. Furthermore, if contact with the epiglottis is lost, the output signal of the accelerometer will drop. 
         [0039]      FIG. 9  also illustrates another notable increase in the output signal of the acceleration when the distal tip of the endoscope is in contact with the anatomical structures above the vocal chords and the laryngeal inlet. This second increase can be detected and used as a second guidepost to indicate when insertion into the larynx is appropriate and insertion is completed. 
         [0040]    Medial alignment of the endoscopic device is sensed in the magnetic domain. The same 6 DOF receiver detects the magnetic signature of the vibrating coil of the loudspeaker  111 . Averaged 3-axis voltages are used to determine not only medial alignment, but also radial distance between the transducer and the distal tip of the endoscope. Quantification of the magnetic field with the endotracheal tube electronics assures location of the endotracheal tube relative to the vibrating transducer. 
         [0041]      FIG. 10  illustrates the live stream output data from 3-axis magnetometer. The graph follows the insertion and removal of the device from the epiglottis, larynx, and vocal membranes. As illustrated by this graph, the magnetometer data can be used to track both extension and rotation of the distal tip of the endoscope throughout the entire range of motion. 
         [0042]      FIG. 11  illustrates the integration of the magnetic sensor input data in the magnetic domain. As shown in this graph, the data is both unique to each point in the trajectory and replicable. With proper calibration, the magnetometer has sensitivity to displacements as small as a millimeter and produces reliable measurements to the nearest half centimeter. 
         [0043]    Based on the output of the accelerometer in response to audio vibrations and the output of the magnetometer in response to the magnetic field applied by the loudspeaker  111 , the system  100  can accurately track movement of the distal tip of the endoscope as it is inserted through the trachea towards the larynx.  FIG. 12  illustrates a method of autonomously controlled insertion based on these signals. 
         [0044]    After the mask is placed on the subject, the loudspeaker magnet is activated, but no sound is initially emitted (step  1001 ). This allows the magnetic sensor positioned at the distal end of the endoscope to calibrate the magnetic field generated by the loudspeaker magnet. After the reference magnetic field is calibrated, the insertion motors are activated and the endoscope is advanced orally into the subject (step  1003 ). Sound output through the loudspeaker is then activated (step  1005 ). 
         [0045]    Throughout the entire insertion process, the magnetic field generated by the loudspeaker magnet is monitored by the magnetic field sensor positioned at the distal end of the endoscope (step  1027 ). If a change in the observed magnetic field indicates that the distal end of the endoscope is no longer centered (step  1029 ), the endoscope tip is moved laterally (step  1031 ) so that medial alignment is properly maintained. 
         [0046]    As the endoscope is inserted, vibrations generated by the loudspeaker are monitored by the accelerometer positioned at the distal end of the endoscope (step  1007 ). As discussed above, the accelerometer signal will increase notably when the tip of the endoscope makes initial contact with the epiglottis. Therefore, linear advancement of the endoscope continues until the accelerometer signal exceeds a first threshold (step  1009 ) indicative of contact with the epiglottis (step  1011 ). Once contact with the epiglottis is detected (step  1011 ), the tip of the endoscope is turned downward (step  1013 ) to follow the anatomical path towards the larynx. 
         [0047]    The accelerometer signal is continually monitored to ensure that the tip of the endoscope remains in contact with the posterior of the epiglottis (step  1015 ). If the accelerometer signal drops below the threshold (step  1017 ), the system determines that contact with the epiglottis has been lost and the tip of the endoscope is turned further downward (step  1019 ) to reestablish contact between the endoscope tip and the posterior of the epiglottis. 
         [0048]    At this point, the accelerometer signal is also compared to a second, higher threshold indicative of contact with the laryngeal inlet (step  1021 ). As long as the signal is greater than the first threshold and less than the second threshold, the system concludes that the tip of the endoscope is in contact with the epiglottis and insertion continues. However, once the accelerometer signal increases above the second threshold (step  1021 ), the system concludes that the endoscope tip is now in contact with the laryngeal inlet (step  1023 ). The endoscope is advanced into the larynx and the insertion motors are stopped (step  1025 ). A tube is then extended over the endoscope, the endoscope is removed, and intubation is complete. 
         [0049]    As noted above, in some constructions, a gyroscopic sensor is positioned in the distal end of the endoscope. The output of the gyroscopic sensor provides a second reference to verify that intubation is on the proper medial track and also ensures that any instrument or drug delivery system is positioned at a correct orientation before administering the drug or operating the instrument. Also, because the intubation tube itself may have a natural curvature, in some constructions the gyroscopic sensor aids in placement of the intubation tube without the need for magnetic fields or a magnetometer, since the tube would tend to follow the natural bend in the throat. 
         [0050]    Thus, the invention provides, among other things, a system and method for autonomous robotic-controlled intubation. By using feedback from accelerometers and magnetic field sensors, the system is able to accurately track movement of the device and detect contact with various specific anatomical structures to control insertion and steering of the intubation device. Various features and advantages of the invention are set forth in the following claims.