WO2025088384A1 - Rapid detection system for tracheal and esophageal intubation - Google Patents

Abstract

The present disclosure describes systems and methods that utilize an ultra-sensitive pressure indicating module that responds rapidly to any changes in the air column inside an Endotracheal Tube. The system includes conventional Endotracheal Tube whose air column is sealed using a flexible tube in conjunction with the ultra-sensitive pressure transducer coupled to a signal generating system. The pressure is represented graphically, and the system activates an alarm unit in case of excessive pressure build up.

Description

Title: Rapid Detection System for Tracheal and esophageal Intubation

Reference: Patents

US5095888A

US5498231A

CN212187391 U

CN216824408U

US9259542B2

CN215135323U

CN213491303

Other patents

Sri Lanka patent Application LK / P / 1 / 22891 (Dare - 23.10.2023) Rapid Intubation Detector (RID).

Disclosure to be disregarded for prior art purposes.

Sri Lanka patent Application LK / P / 1 / 22891 (Dare - 23.10.2023) Rapid Intubation Detector (RID).

References: Other:

Schwartz DE, Matthay MA, Cohen NH. Death and other complications of emergency airway management in critically ill patients: a prospective investigation of 297 tracheal intubations. Anaesthesiology 1995;82:367-376.

Jaber S, Amraoui J, Lefrant JY. Clinical practice and risk factors for immediate complications of endotracheal intubation in intensive care unit: A prospective multiple-center study. Critical Care Medicine 2006;34:2355-2361 .

Jaber S et al. An intervention to decrease complications related to endotracheal intubation in the intensive care unit: a prospective, multiple-center study. Intensive Care Medicine 2010;36:248-255. Mort TC. Emergency tracheal intubation: complications associated with repeated laryngoscopic attempts. Anesthesia & Analgesia. 2004;99:607-613.

Mort TC. Esophageal intubation with indirect clinical tests during emergency tracheal intubation: a report on patient morbidity. Journal of Clinical Anesthesia 2005;17:255-262.

Mort TC. Unplanned extubations outside the operating room: A quality improvement audit of hemodynamic and tracheal airway complications associated with emergency tracheal reintubation. Anesthesia & Analgesia. 1998;86:1171-1176.

Technical Problem

The insertion of an endotracheal tube to the trachea during general anesthesia is essential for ensuring the supply of oxygen to the lungs. This process is done by an anesthetist taking care to avoid oesophageal intubation. Rapid detection of oesophageal intubation is necessary to prevent life threatening situations. The available devices for this detection takes a substantial time and hence the need for a rapid detection technique.

Technical Solution

The present disclosure relates generally to systems and methods to intubate a patient, and more particularly to systems and methods to recognize and rapidly act in case of oesophageal intubation.

IPC Classification (Intubation)

A61 M 16/00 Devicesfor influencing the respiratory system of patients by gas treatment, e.g. mouth-to-mouth respiration; Tracheal tubes (stimulating the respiratory movement by mechanical, pneumatic or electrical means, iron lungs combined with gas breathing means A61 H 31/00) [2006.01],

Background of the invention

The present disclosure relates to medical apparatus used in the field of anesthesiology and to methods to ensure mistake-free tracheal intubation. It is common practice to use an Endotracheal Tube (ETT) to give mechanical breathing I artificial ventilation during general anesthesia. The ETT comprises a rigid air conduit constructed of medical grade plastics that is to be placed in the patient's trachea. The distal end of the ETT used in general applications has a side hole thatenables the air flow in case of an obstruction in the main passage.The proximal end of the ETT has a standard fitting that allows the connection to an external source of pressurized gas such as oxygen, air and anesthetic gases by the breathing system.

The ETT could be correctly placed in the trachea under direct visualization using a laryngoscope. The popularly used conventional laryngoscope is considered as the most successful durable instrument in the history of anesthesia. There exists a vast number of patents based on this design. US patents US5095888A & US5498231A are two such examples.

Anatomical and physiological aspects of intubation

Anatomically, the esophagus is a muscular tube whose size ranges from 18 to 26 cm in length and it serves as a passageway for food and liquids to travel from the mouth to the stomach. It is usually an airless, self-collapsing tube that resembles an organ that naturally collapses when at rest. Meanwhile the trachea, also known as windpipe, is a hollow conduit which permits inhaled and exhaled air to pass from upper airway to both bronchi. The trachea is in the upper anterior part of the chest and oesophagus lies behind it. As shown in Fig. 3. The trachea shown in Fig.3, consists of a series of C-shaped cartilage rings (209), numbering between 16 &22. The cavity (208) of the tracheawill maintain its hollow shape even after the patient is subjected to general anesthesia. In contrast, esophagus(201 ) collapses (202)when the patient is in the supine position under general anesthesia as shown in Fig. 3.

The vocal cords (205) of the patient needs to stay open to enable the insertion of the ETT. Fig. 2 shows the open vocal cord condition as opposed to its closed condition. Under general anesthesia, muscular paralysis takes place. Hence the vocal cords are subjected to paralysis and remain open position.

Under general anesthesia, the lungs are at their functional residual capacity (FRC) and the patient is unable to breathe due to muscle paralysis. As a result, the environment and lung alveoli will continue to retain the same air column with no air flow. It means that the air contained in the lung (alveoli) isconnected withthe atmospheric pressure via the trachea. So internal pressure of the trachea is equal to the atmospheric pressure. The patient has to be externally supplied with Oxygen, air and other gasses during general anesthesia, to provide ventilation and to maintain anesthesia. This is achieved by performing mechanical ventilation via the Endotracheal Tube (ETT)placed in the trachea.

The insertion of the ETT is a skilled procedure performed by an experienced clinician such as anesthetist. The major challenge is to ensure that the ETT is placed in the trachea and not in the esophagus. The placement of an ETT in the esophagus, which is termed as oesophageal intubation, can be catastrophic within minutes. It is important to detect esophageal intubation at the earliest possible instance as any delay can lead to a life-threatening clinical condition including death.

Complications that arise from oesophageal intubation are well documented in research literature. A few selected studies are given here.

In a research publication by Schwartz et al. in “Death and other complications of emergency airway management in critically ill patients: a prospective investigation of 297 tracheal Intubations” published in Anaesthesiology 1995, 82 reports that out of 297 emergency intubations in an intensive care unit, there was an initial failure rate of 11 % due to oesophageal intubation.

Another multi-centre study conducted by Jaber et al. published in CritCare Med 2006, 34, says that out of 253 ICU intubations, 28% of the patients experienced severe life-threatening consequences due to wrong placement of the Endotracheal tube (ETT).

Mort TC. in AnesthAnalg 2004, 99 states that, in a study of more than 10,000 emergency intubations, multiple attempts at laryngoscopy were associated with increased risks of complications. More than two laryngoscopy attempts experienced a seven-fold increase in hypoxia, a six-fold increase in oesophageal intubation, a seven-fold increase in regurgitation, a four-fold increase in aspiration, and seven-fold increase in cardiac arrest as compared to those requiring just one or two laryngoscopes.

Proper intubation requires positioning the distal end (100) of the ETT within the trachea, below the vocal cords (205).As will be appreciated from the foregoing statements, a need exists for an apparatus and methods for facilitating safer and the rapiddetection of endotracheal intubation. The Rapid Tracheal Esophageal Intubation Detector disclosed herein will satisfy this dire need.

In this context, any technique for the rapid detection of incorrect intubation, namely oesophageal intubation, will be a welcome move. The present inventive technique disclosed will help to alleviate this situation by identifying oesophageal intubation in a very short time span.

Introduction to Rapid Tracheal & esophageal Intubation Detector

Intubation process requires the insertion of an artificial airway such as ETT to the trachea using laryngoscopy. Orotracheal tube is more common than the nasotracheal tube. There are both clinical and technical tests that have been developed to determine the endotracheal tube position. There are different esophageal detector devices in the prior art, that can differentiate oesophageal intubation from tracheal intubation.

Prior Art

Some of the methods adopted presently for the identification of oesophageal intubation are mentioned here.

1 . Visual confirmation during intubation:

After intubation, the ability to see the tube passing between the vocal cords and anterior to the arytenoids should be assessed before withdrawing the laryngoscope blade.

2. Sustained continuous Capnography monitoring:

In the medical world, capnography is considered as the gold standard technique to differentiate tracheal intubation from oesophageal intubation. Capnography is the monitoring of the concentration or partial pressure of carbon dioxide (CO₂) in the exhaled air. Its main development has been as a monitoring tool for use during anesthesia and intensive care. The observed values are presented as a graph of carbon dioxide (CO₂) plotted against time.

This current gold standard method is based on measuring the carbon dioxide (CO₂) waveform using Capnography. However, the drawback of this method is the initial delay in producing the wave form. Thus any case of incorrect intubation is detected only after the lapse of this delay. Successful placement of the ETT in the trachea takes more than 30 seconds by the adoption using the present techniques. This duration will depend on the clinician’s experience and skills. If a faulty placement is indicated, the ETT has to be removed and repositioned immediately before the patient suffers serious consequences. Another complication in the present process is that, sometimes oesophageal intubation can also produce carbon dioxide (CO₂) wave form due to the presence of some exhaled CO2 which has entered the oesophagus during bag-mask ventilation which leads to mis-interpretation about the placement of ETT. This is another drawback of the capnography. Many devices and techniques have been introduced to help the detection of oesophageal intubation. Some such patents are given here.

The Chinese patent CN212187391 II discloses a pressure monitorable endotracheal tube ETT comprising an air pressure sensor and a pilot indicator. It uses a tracheal catheter to obtain the pressure.

CN216824408U also discloses a tracheal catheter capable of quickly judging the position of the ETT using the colour change of a carbon dioxide test paper placed at the inner wall of the transparent annular joint.

The device disclosed in US8998798B2 utilizes a multi-lumen tube with an integral visualization apparatus, such as a camera. It is an extended visualization device. In US9259542B2, a differential ultra-sensitive pressure transducer determines and monitors the pressure differentials between the breathing track and the ambient. It does not indicate the pressure in the esophagus.

An End-tidal carbon dioxide guide intubation tube capable of monitoring carbon dioxide content is disclosed in CN215135323U. It measures the flow of carbon dioxide from the lungs and has visual tools to help make sure the tube is in the right place.

In the Relay Trachea Cannula disclosed in CN213491303 the airflow is monitored using a microphone airflow sensor. The sensor is activated by pressing the abdominal area of the patient.

Detailed Description of the Invention

Description of components

The preferred embodiment of the device disclosed here is based on a conventional Endotracheal Tube (ETT) (102) of prior art and consists of a flexible tube extending from the distal end (100) to the connector at the proximal end (114) as shown in Fig 4. It is used to assist the breathing process during a surgery or to support breathing in case of a lung malfunction, chest trauma orairway obstruction. The cuff (101) disposed at the distal end (100) is inflated using the pilot balloon (103) disposed close to the proximal end (114) of the ETT. Once inflated, the cuff provides a seal within the airway preventing the passage of air around the ETT (102)and prevents mouth secretions entering the lung. The standard 15mm connector (104) at the proximal end (114) is the same used in the prior art applications. The present device is plugged into this standard 15mm connector (104) via the female adapter (105) which carries a non-elastic minimal flexible tube (106). The minimal flexible tube (106) carrying the vital signals is connected to the ultra-sensitive pressure transducer (108) of monitoring device of this disclosure via the connector (107).

During the passage of the ETT through the trachea and esophagus, mechanical stress is generated. This stress will in turn generate a pressure change in the air column inside the ETT (102). Due to differences in the tissue structure in the trachea and the esophagus the mechanical stress produced and hence the pressure values are different in two cases. This pressure change in the ETT air column and the flexible tube (106) is conveyed to the ultra-sensitive pressure transducer (108) via the connector (107). The ultra-sensitive pressure transducer (108) is directly connected to motherboard (112) using the connector wire 1 (109). The motherboard (112) sends signals to the Bluetooth and the Wi-Fi module (111) via the connecting wire 2(110). The power required for the system is supplied through the external AC or DC power supply unit (113).

Signal from the Bluetooth and the Wi-Fi module (111 ) can be received by any Android and Apple device installed with the custom designed App.

This forms the basis of the Rapid Detection System for Tracheal and Esophageal Intubation Disclosed.

Supplementary equipment in the preferred embodiment of the present disclosure:

Ultra-sensitive pressure transducer

The ultra-sensitive pressure transducer (108) is used to convert mechanical pressure in the air column to a signal in the form of an electrical signal. The motherboard (112) receiving the signal identifies and amplifies it. It produces a corresponding waveform, which can be transmitted via the connected Bluetooth and Wi-Fi modules (111 ). In general, Android and Apple devices can receive this transmitted data and produce a graph according the pressure change while advancing the ETT.

Data processing and analysis system in the preferred embodiment

The HX-710B pressure sensor and transducer is a unit that can sense pressure and convert mechanical stress to an electrical signal.

Data processing unit, the motherboard (112) is an Arduino mega board.

The Bluetooth Module HS-06 is a Bluetooth 2.0 protocol-based device enabling short-range wireless data communication between microcontrollers or systems and the Wi-Fi module is a ESP-8266 Wi-Fi Module which is a versatile short-range wireless data communication solution, enabling high-speed connectivity between microcontrollers or systems operating at a 2.4 GHz frequency.

The signal from the Bluetooth module can be received by Android tablet, phone, or any Bluetooth device and anyWi-Fidevice can accessWi-Fi data in a remote manner.

Analysis and the plot of the data is done by MIT App Inventor 2, an intuitive web-based application. This specially designed App is compatible with Android and Apple devices. The App helps to magnify signal and produce a highly sensitive signal with a good magnification.

Description of the mechanism

The non-elastic minimal flexible tube (106) of the present device is fitted to the conventional ETT (102) using standard 15mm connector (104) and the female adapter (105). The Bluetooth And Wi-Fi module (111 ) should be kept in the active mode.

The patient undergoing general anesthesia is now laid down on the theater table in the supine posture. The recommended dose of anesthetics is now administered. After a lapse of 3-4 minutes of face-mask ventilation, the patient achieves sufficient paralysis. The Anesthetist now inserts the ETT (102) in to the patient through the open vocal cord (205). The ETT (102) gradually passes in and should get landed in the trachea (200) and not the oesophagus (201).

If it lands in the trachea as expected, it gets positioned there comfortably. Now the cuff (101 ) is inflated using the pilot balloon (103). And the system will perform as expected. The patient will be able to be supplied with breathing air, Oxygen and other gases to maintain anesthesia. Ideally the ETT should be placed correctly in trachea (204). Incorrectly placed ETT is (203) leads to complications.

The principle of the present invention is explained here.

Main addition of the present disclosure is the adapter and the associated system. New device has a female adapter to connect to proximal end of the ETT. So, it will seal the air column in the ETT. This adapter, together with the associated system should be connected to ETT before intubation.

Trachea is an open cartilaginous stiff structure whereas the esophagus is muscular in composition. The cavity of trachea remains open due to the C-shaped rings (209) which are stiff in structure. The cavity in trachea is ready to accept the ETT without any resistance. Once the ETT goes into the trachea, the pressure inside the ETT equalizes with that in the ambient as excess air in the system will escape through the gap surrounding the ETT.

On the other hand, the esophagus is in a collapsed state when the patient is under anesthesia. The ETT has to be pushed into the collapsed esophagus by the anesthetist administering the system. This situation is illustrated stepwise in the figures 5-8. This can be explained as follows.

Fig. 5 illustrates the position A of the ETT when it is about to touch the esophagus. Fig. 6 shows the ETT at position B, when the ETT almost touches the esophagus. At this position, the distal end (100) of the ETT traps a small amount of air from the air present in the free space around it. This small pocket of air (211 ) is connected to the air column inside the ETT. The pushing action causes a slight fluctuation in the pressure in the air column. This does not happen when the ETT is in the trachea and can be termed as tissue resistance. This distinction is used to detect oesophagus intubation in the present disclosure.

The points A and B shown in the pressure graph refer to the positions A & B in Fig. 5 and Fig. 6 respectively. Once the ETT enters the esophagus the pressure increases further. This position C is illustrated in Fig. 7 and the corresponding pressure in the pocket of air (212) is shown at C in Fig. 9. When the ETT is pushed further into the esophagus to position D of ETT shown in Fig. 8, the pressure in the small pocket of air (213) will increase further (point D in the graph). Once the ETT is removed from the esophagus, the pressure signal returns to the base value (point E in the graph). It is clear that there is no pressure peak in the case of trachea (Fig.10) compared to oesophagus intubation (Fig. 9).

Fig. 9 & Fig. 10 show the pressure signal produced via the custom designed App for Android and Apple device, when the ETT is inserted into the esophagus and trachea respectively. As shown in Fig. 9 & Fig. 10, the maximum pressure obtained in oesophageal intubation is 3.0-5.0 cmH20 and the maximum pressure obtained in tracheal intubation is 0.1 -1.0 cmH20.

Since the oesophageal intubation is detected rapidly, it can be corrected immediately. This is a great advantage for the medical professionals and to the patients.

The device in the present disclosure is to recognise the point of entry of the ETT into the oesophagus. The time delay between the point of entry and the indication by the device is less than 1 second. The sudden increase in pressure is set to activate a visible and an audible signal.

Thus this device qualifies as the Rapid Tracheal Esophageal Intubation Detector. Its functionality is far superior to any other detection technique in prior art. Brief description of the Drawings

Fig. 1 (a) shows the case when the ETT is in the esophagus. This situation can lead to life-threatening complications in the patient and has to be avoided.

Fig. 1 (b) shows when the ETT is correctly inserted in the trachea. This is the required status of the ETT.

Fig. 2 is the entry point of the ETT. The ETT has to pass through the opening of the vocal cord.

Fig. 3 shows a detailed view of the trachea anterior and the esophagus posterior in the collapsed status.

Fig. 4 is a skeletal representation of the system in disclosure attached to the proximal end of the ETT.

Fig. 5 - Fig. 8 show the critical positions of the distal end of the ETT required to understand the principle of the inventive method.

Fig. 5 shows the position A of the ETT when it is close to the collapsed esophagus. There is no effect on the air column at this point.The pressure is at the base value.

Fig. 6 shows the position B of the ETT when the distal end (tip) touched the collapsed oesophagus. The pressure in the air pocket trapped at the tip will start to increase.

Fig. 7 shows the position C of the ETT when the distal end (tip) after it enters the collapsed esophagus. The pressure in the air pocket will remain elevated beyond this point.

Fig. 8 shows the position D of the ETT when the distal end (tip) is inside the collapsed esophagus. The pressure in the air pocket will remain elevated. Fig. 9 is the graph of pressure inside the ETT as sensed by the Ultra-sensitive pressure sensor when the ETT goes through oesophageal intubation, is shown in the android and apple devices with specially designed App.

Fig. 10 is the graph of pressure inside the ETT as sensed by the Ultra-sensitive pressure sensor when the ETT goes through tracheal intubation, is shown in the android and apple devices with specially designed App.

Claims

Title: Rapid Detection System for Tracheal and Esophageal Intubation

Claim 1

A system and a process to detect esophageal Intubation by monitoring the pressure pattern in the endotracheal tube during the movement of the endotracheal tube in the trachea & esophagus comprising, an endotracheal tube a minimal flexible tube and a pressure sensing module

Claim 2

A system and a process to detect esophageal Intubation in claim 1 using the differential pressure in the endotracheal tube sensed by the tissue resistance created at the oesophagus.

Claim 3

A system and a process to detect esophageal Intubation in claim 1 using the differential pressure in the endotracheal tube sensed by the tissue resistance created at the trachea.

Claim 4

A system and a process to detect esophageal Intubation in claim 1as opposed to tracheal intubation using the differential pressure in the endotracheal tube comprising an ultra-sensitive pressure transducer.

Claim 5

A system and a process to detect esophageal Intubation in claim 1 using the differential pressure in the endotracheal tube comprising, a processing system for real time information from an ultra-sensitive pressure transducer a signal amplification system and an automated data transmission system using a Bluetooth module and a Wi-Fi module Claim 6

A system and a process to detect esophageal Intubation in claim 1 using the differential pressure in the endotracheal tube, comprising an automatic alarm system.

Claim 7

A system and a process to detect esophageal Intubation in claim 1 using the differential pressure in the endotracheal tube generated by the tissue resistance present at the esophagus as opposed to tissue resistance present at the trachea.

Claim 8

Rapid Tracheal & Oesophageal Intubation Detector comprising, an endotracheal tube a female adapter a minimal flexible tube and a pressure sensing module.

Claim 9

Rapid Tracheal & Oesophageal Intubation Detector in claim 8 wherein, a minimal flexible tube is disposed to convey the pressure in the endotracheal tube to the ultra-sensitive pressure transducer.

Claim 10

Rapid Tracheal & Oesophageal Intubation Detector in claim 8 wherein, a complete sensor and detector unit comprises an ultra-sensitive pressure transducer, an electronic motherboard a Bluetooth module and a Wi-Fi module