Patent Application
20140275836
Patient safety is one of the most important challenges facing today's healthcare environment, and is a top priority for improvement of the quality of care. Inadvertent esophageal intubation and unsuccessful endotracheal intubation that is not recognized in time continue to cost thousands of lives each year. These events occur regularly in the intensive care unit (ICU), operating room, emergency department, and in many circumstances, at the scene of emergency events by first responders.
Current standards for clinical practice to confirm a successful endotracheal intubation rely on the clinician to evaluate adequate chest rise with each inspiration and airway flow sounds on auscultation of the lungs. However, current practice does not prevent many of the possible human errors that can jeopardize patient safety. The apparent problems with current practice are: 1) a clinician neglects to check on chest rise and breath sounds; 2) a wrong assessment or inadequate experience of the clinician; 3) the time involved in the process may delay resuscitation effort; and 4) the assessment of an endotracheal intubation determination is not always possible in a crowded noisy (frantic) situation.
The use of capnography devices has gained wide popularity by many clinicians. Capnography devices are designed to detect CO2 coming out of the endotracheal tube during expiration. Problems with use of such devices include: 1) the additional time and extra steps need for such confirmation; and 2) the possibility of non-detection of expiratory CO2 in a patient in full cardiac arrest. Furthermore, capnography devices cannot detect conditions such as right main stem intubation and pneumothorax.
A device for use in assessing intubation is disclosed, as is a method for assessing intubation. In one embodiment, a device includes an accelerometer and one or more microphones contained in a housing that can be placed on a subject's chest. The device assesses intubation by 1) chest rise; and 2) airway sounds by auscultation. In one embodiment of the device, the chest rise will be assessed by a tri-axial accelerometer, and airway sounds will be assessed by an acoustic microphone.
Chest rise can be difficult to assess by inexperienced clinicians, in a crowded, busy and distractive setting or environment with inadequate lighting. However, chest rise can be precisely and objectively assessed by an accelerometer. A typical tri-axial accelerometer can detect acceleration and deceleration from all 3 axes at a sensitivity of less than one millimeter (mm).
Disposed within enclosure 110 of device 100 in this embodiment are accelerometer 130, microphone sensor 140, microphone sensor 150, microcontroller unit 140 and button 170. In one embodiment, accelerometer 130 is a tri-axial accelerometer based on the HDK HAAM-372. These accelerometers have the range of ±2 g and ±8 g, and a digital output that minimizes noise. The accelerometers feature programmable threshold detection, such that a microcontroller unit (MCU) can be put to sleep and awakened by motion triggering. In one embodiment, an accelerometer-only, gyroscope-free inertial measurement unit (GF-IMU) will be used for motion tracking (see EcoIMU: A Dual Triaxial-Accelerometer Inertial Measurement Unit for Wearable Application by Yi-Lung Tsai, et al., Proc. International Conference on Body Sensor Networks (BSN 2010), Singapore (Jun. 7-9, 2010), pp. 207-212). Accelerometer 130 is configured to detect motion, specifically, chest motion during at least one of inspiration and expiration. An algorithm for motion detection based on accelerometer data has been developed and tested.
In one embodiment, microphone sensor 140 and microphone sensor 150 are electret or piezo sensors. Microelectromechanical (MEM) sensors can also be used. In one embodiment, microphone sensor 140 is placed in the center of enclosure 110 corresponding to (e.g., sensor facing) the skin contact surface of the device with acoustic diaphragm 120 to augment the respiratory sound. Microphone sensor 150 may be placed at a top surface of the device facing the ambient environment, in order to detect ambient noise. In one embodiment, ambient noise detected by microphone sensor 150 is used for noise subtraction (e.g., subtracted from sound detected by microphone sensor 140) to enhance the respiratory sound signals. In another embodiment, the two microphone sensors of device 100 may be replaced with a single microphone to detect respiratory sounds. In one embodiment including a single microphone sensor, the microphone sensor includes noise subtraction functionality to reduce the presence of non-respiratory sounds (e.g., ambient sounds).
In addition to the sensors (accelerometer and one or more microphones), device 100 also includes microcontroller unit (MCU) 160 for signal processing based on a predetermined algorithm. MCU 160 is communicatively connected to the sensors of device 100. Battery 170 of, for example, a lithium polymer type is also included and is connected to MCU 160 and the sensors to provide power to the device. Lithium polymer batteries have high charge density and good power density, which are needed for burst (peak-power) processing patterns. Such a battery can be made as lightweight as 1.2 grams with a capacity of 90 mAh at 3.7-4.2 V. In one embodiment, battery strength is monitored periodically by MCU 160. Battery 170 can be recharged using conductive (line in) or inductive (wireless) mechanisms.
A representative algorithm includes a set of non-transitory instructions to query and/or receive signals from the sensors and to transmit signals. MCU 160 may also include a memory (e.g., flash memory such as micro-SD card) to record receipt and transmission of sensor signals. In one embodiment, wireless transmitter, based on radiofrequency such as Bluetooth 4.0 protocol, is installed for transmission of chest rise and sound signals to a remote receiver. The transmitted data on monitoring of the endotracheal intubation procedure may be integrated with the patient's electronic medical record (EMR) for recording keeping and documentation, and for offline review as a part of quality assurance and education.
On and optionally protruding from a surface of enclosure 110 opposite diaphragm 120 are power button 175, indicator light 180, and dial 185, as shown in
Device 100 can be used by emergency first responders, paramedics, emergency room physicians, nurses, respiratory therapist, intensivists, anesthesiologists, and clinicians in any of the settings that endotracheal intubation takes place. Device 100 can be bundled with a laryngoscope in an intubation tray; or as a standalone device to be kept in stock in a crash cart, in the operating room, or in the ambulance. In addition, this can also be a pocket device a clinician who is frequently involved in intubation procedures (e.g., anesthesiologists, respiratory therapists) carries on a daily basis.
Device 100 is to be placed on the patient's left chest, to the left of sternum at 4th intercostal space (medial to the left nipple). The unconscious patient should be supine, with chest exposed, and without movement interference (chest compression). In one embodiment, the user presses power button 175 first, then firmly places device 100 on the left chest and attaches the device using suction or disposable adhesive surface 120. The user proceeds with intubation by placing an endotracheal tube while the indicator light flashes red once per second. The sensors of device 100 continue to monitor the charges (presence and absence of chest rise and airway sounds). In one embodiment, once the user thinks the endotracheal tube is in place, a self-inflatable bag-valve device is connected to the endotracheal tube for ventilation. Once the sensors detect definitive signals indicating three consecutive respiratory cycles of chest rise and inspiration/expiration, the indicator light will change to a solid green.
Table 1 summarizes the algorithms for detection of different clinical conditions, including esophageal intubation, right main stem intubation, and possible pneumothorax.
Where the sensors do not indicate three respiratory cycles of chest movements and corresponding inspiratory/expiratory breath sounds, MCU analyzes the sensor signals for conditions other than successful intubation (block 270). In one embodiment, MCU 160 analyzes for conditions of right main stem intubation, esophageal intubation, blocked endotracheal tube, pneumothorax, or chest movement artifacts (e.g., chest movement associated with an extraneous action such as chest compressions) (block 275). If any of the conditions are detected, MCU 160 directs indicator 180 to illuminate an indicator light of red (or, in one embodiment, amber in the case of right main stem intubation) (block 280). MCU 160 will continue monitoring the sensors and directing indicator 180 until device 100 is powered off.
In another embodiment of a device, a display screen such as a liquid crystal display (LCD) or light emitting diode (LED) screen is placed on the top surface of device 100. In addition to the indicator light, display screen 190 can visually display the results of accelerometer and microphone airway sounds, and the interpretation of the sensor inputs listed in Table 1. In one embodiment, MCU 160 can direct screen to display the condition detected by analysis of the sensor data in text form in display screen 190. The interpretations of the results displayed on the display screen may assist clinicians with assessment and decision making in the events of possible right main stem intubation, blocked endotracheal tube or pneumothorax.
In some settings, such as pre-hospital care by paramedics, supraglottic (or extra-glottic) airway (SGA) devices are used. Examples of SGA devices include laryngeal mask airway (LMA), Combi-tube, and King LT airways. In these devices, a tube is placed in the esophagus or in the oropharynx instead of the trachea. However, successful placement of SGA devices (successful intubation) and effective ventilation can be assessed by the same method of combined input using chest movement and air movement sounds. Therefore, the proposed device, method and algorithm will be as effective for detecting SGA placement and ventilation as they do for endotracheal intubation.
Advantages of a device such as described for assessing intubation include that the device requires no skill or training to use (operator independent and fool proof); results are clearly presented by indicator light; saves time repeated assessments of the chest rise and auscultation; detects right main stem intubation, and possibly pneumothorax; standardizing intubation assessment procedure; and easy documentation (a check box on paper or in EMR), the device can be easily integrated with the Quality Improvement protocols in the operating room, emergency department, or ICU to reduce rate of unintended and unrecognized esophageal or right main stem intubation.
In the description above, for the purposes of explanation, numerous specific details have been set forth in order to provide a thorough understanding of the embodiments. It will be apparent however, to one skilled in the art, that one or more other embodiments may be practiced without some of these specific details. The particular embodiments described are not provided to limit the invention but to illustrate it. The scope of the invention is not to be determined by the specific examples provided above but only by the claims below. In other instances, well-known structures, devices, and operations have been shown in block diagram form or without detail in order to avoid obscuring the understanding of the description. Where considered appropriate, reference numerals or terminal portions of reference numerals have been repeated among the figures to indicate corresponding or analogous elements, which may optionally have similar characteristics.
It should also be appreciated that reference throughout this specification to “one embodiment”, “an embodiment”, “one or more embodiments”, or “different embodiments”, for example, means that a particular feature may be included in the practice of the invention. Similarly, it should be appreciated that in the description various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure and aiding in the understanding of various inventive aspects. This method of disclosure, however, is not to be interpreted as reflecting an intention that the invention requires more features than are expressly recited in each claim. Rather, as the following claims reflect, inventive aspects may lie in less than all features of a single disclosed embodiment. Thus, the claims following the Detailed Description are hereby expressly incorporated into this Detailed Description, with each claim standing on its own as a separate embodiment of the invention.
The application claims the benefit of the earlier filing date of co-pending U.S. Provisional Patent Application No. 61/788,616, filed Mar. 15, 2013 and incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61788616 | Mar 2013 | US |
