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EP-4740987-A2 - FLOW THERAPY SYSTEM

EP4740987A2EP 4740987 A2EP4740987 A2EP 4740987A2EP-4740987-A2

Abstract

There is disclosed system for oxygenating a patient in relation to anaesthesia using high flow gas delivery. The system has a flow source, and a controller for determining oxygenation requirements of the patient before or during anaesthesia. A method of oxygenating a patient in relation to anaesthesia using high flow gas delivery is also disclosed. The method determines oxygenation requirements of the patient before or during anaesthesia.

Inventors

  • PAYTON, MATTHEW JON
  • HARWOOD, JONATHAN DAVID
  • OLDFIELD, Samantha Dale
  • SPENCE, CALLUM JAMES THOMAS
  • ASSI, Milanjot Singh
  • EVANS, Alicia Jerram Hunter
  • BARNES, Thomas, Henrich
  • CHEUNG, DEXTER CHI LUN
  • WHITE, CRAIG KARL
  • WILLIAMS, Anthony Brendan
  • GULLIVER, LAURENCE
  • BARRACLOUGH, Michael
  • CHURCH, JONATHAN MARK

Assignees

  • Fisher & Paykel Healthcare Limited

Dates

Publication Date
20260513
Application Date
20160218

Claims (15)

  1. An apparatus for estimating and/or determining one or more pre-oxygenation parameters for a patient undergoing pre-oxygenation therapy, the apparatus comprising: an unsealed nasal interface; a flow source configured to providing pre-oxygenation therapy to the patient via the unsealed nasal interface, wherein the flow source provides a flow of gases with a flow rate greater than 15 L/min; one or more sensors configured to measure and/or track the concentration of oxygen in the patient's expired gas; wherein the apparatus estimates and/or determines the one or more pre-oxygenation parameters from the sensor measurements.
  2. The apparatus according to claim 1, wherein the one or more pre-oxygenation parameters comprise: a) the time until a patient undergoing a pre-oxygenation procedure has been sufficiently pre-oxygenated, b) the likelihood of a pre-oxygenation procedure achieving a target end-tidal oxygen level for a patient, c) the end-tidal oxygen level for a patient undergoing a pre-oxygenation procedure, d) if a patient has been sufficiently pre-oxygenated during a pre-oxygenation procedure, e) changes in pre-oxygenation level of a patient undergoing a pre-oxygenation procedure.
  3. The apparatus according to claim 1 or claim 2, wherein measurements at or around the initial phase of the pre-oxygenation procedure may be used to predict the time remaining until there is sufficient pre-oxygenation.
  4. The apparatus according to any one of claims 1 to 3, wherein the expired oxygen concentration is monitored throughout the pre-oxygenation process and the predicted time is adjusted as the process continues.
  5. The apparatus according to any one of claims 1 to 4, wherein sufficient pre-oxygenation is indicated by one or both of: a sustained end-tidal oxygen concentration, optionally wherein the sustained end-tidal oxygen concentration is greater than 70%, such as 87% or greater than 90%; and blood oxygen saturation level greater than 90%.
  6. The apparatus according to any one of claims 1 to 5, wherein the measuring and/or tracking of the concentration of oxygen in the patient's expired gas is performed using a mass spectrometer.
  7. The apparatus according to any one of claims 1 to 5, wherein the measuring and/or tracking of the concentration of oxygen in the patient's expired gas is performed using a gas analyser, and optionally wherein the gas analyser is positioned proximal to the flow source.
  8. The apparatus according to any one of claims 1 to 7, wherein the one or more sensors are configured to measure and/or track the concentration of oxygen in the patient's expired gas continuously.
  9. The apparatus according to any one of claims 1 to 8, wherein the apparatus further comprises a processor configured to: a) estimate the rate of change of the patient's expired oxygen concentration; and/or b) fit a rate of change of the patient's expired oxygen concentration to a non-linear model, and/or b) determine a time constant for said model, and optionally c) multiply the time constant with a treatment factor to estimate the time until sufficient pre-oxygenation may be achieved, and/or d) indicate when the patient has been sufficiently pre-oxygenated. wherein the time constant is the time taken for the concentration of oxygen in the expired gas to increase by substantially 63% of the difference between a desired level and the concentration of oxygen in a first measurement of expired gas.
  10. The apparatus according to claim 9, wherein the processor further comprises a countdown timer configured to indicate estimated time remaining until the patient is sufficiently pre-oxygenated; and optionally wherein: the timer has a user interface in the form of coloured lights; and/or there is audio or visual indication when pre-oxygenation is complete.
  11. The apparatus according to any one of claims 1 to 10, wherein the flow rate of gases provided is greater than or equal to about 20 L/min, or wherein the flow rate of gases provided is in a range from 30 L/min to 150 L/min.
  12. The apparatus according to any one of claims 1 to 11, wherein the apparatus further comprises a humidifier to humidify the flow of gases.
  13. The apparatus according to any one of claims 1 to 12, further comprising one or both of: one or more sensors configured to measure and/or track the concentration of one or more respiratory gases in the patient's blood; and wherein the measuring and/or tracking of the concentration of one or more respiratory gases in the patient's blood is performed via pulse oximetry.
  14. The apparatus according to any one of claims 1 to 13, wherein the apparatus is further configured to display the concentration of oxygen in the patient's expired gas to a user.
  15. The apparatus according to any one of claims 1 to 14, wherein the unsealed nasal interface comprises a sensing module comprising the one or more sensors configured to measure and/or track the concentration of oxygen in the patient's expired gas; and optionally wherein the sensing module comprises the gas analyser.

Description

TECHNICAL FIELD The present disclosure generally relates to respiratory gas therapy. More particularly, the present disclosure relates to respiratory gas therapy systems, apparatuses, kits and methods for treating patients undergoing anaesthetic or anaesthesia related procedures. DESCRIPTION OF THE RELATED ART Intubation is often practiced on patients who are unable to spontaneously breathe. The inability to breathe may be the result of one or several factors, including severe illness, injury, or deep sedation through the use of a general anaesthetic agent. A challenge for anaesthesiologists, including emergency, intensive care and surgical physicians, is to secure a tracheal tube (i.e., intubate) rapidly without causing hypoxia. In the best case intubation may take 45-60 seconds; however, in other cases, particularly if the patient's airway is difficult to traverse (for example, due to cancer, obesity, or severe injury), intubation can take much longer. Patients who are breathing room air will desaturate within this time between sedative/paralytic administration and achieving a secured airway. A patient desaturates when the oxygen concentration in their blood reduces. To prevent hypoxemia during intubation, a medical professional performing the intubation will often pre-oxygenate the patient to be intubated by applying a face mask and delivering oxygen for a period of time until the patient's blood oxygen saturation level (measured using, for example, near infrared spectroscopy, pulse oximetry, or any other suitable process and equipment) reaches approximately 100%. Pre-oxygenation can provide a buffer against undesirable declines in oxygen saturation, but for long intubation procedures, it is often necessary to interrupt the intubation process and reapply the face mask to again increase the patient's oxygen saturation level to adequate levels. The interruption of the intubation process, which can happen several times for a difficult intubation process, can be frustrating to the medical professional. Additionally, the patient can experience rises in blood carbon dioxide due to the poor management of physiological dead space. Similar difficulties can be encountered with sedated spontaneously breathing patients undergoing, for example, upper endoscopies. Pre-oxygenation with 100% oxygen or almost 100%, (for example 90% or higher) has been shown to markedly increase the duration of safe apnea - defined as the time until a patient reaches a blood oxygen saturation level of 88-90%. Saturations below this level can rapidly deteriorate to critical levels (<70%) on the oxyhemoglobin dissociation curve posing significant risk to the patient. Ideally patients should continue to receive pre-oxygenation until they achieve greater than 90% end-tidal oxygen levels, showing the lungs have been denitrogenised and an oxygen reservoir established in the functional residual capacity of the lungs. Denitrogenation of the lungs creates an alveolar oxygen reservoir that serves to maintain oxygen saturation levels for a small post-ventilatory window. Patients may lose respiratory function during anaesthesia, or sedation, or more generally during certain medical procedures. Prior to a medical procedure a patient may be pre-oxygenated by a medical professional to provide a reservoir of oxygen saturation, and this pre-oxygenation is generally carried out with a bag and a face mask. Once under general anaesthesia, patients must be intubated to ventilate the patient. In some cases, intubation is completed in 30 to 60 seconds, but in other cases, particularly if the patient's airway is difficult to traverse (for example, due to cancer, severe injury, obesity or spasm of the neck muscles), intubation will take significantly longer. While pre-oxygenation provides a buffer against declines in oxygen saturation, for long intubation procedures, it is necessary to interrupt the intubation process and reapply the face mask to increase the patient's oxygen saturation to adequate levels. The interruption of the intubation process may happen several times for difficult intubation processes, which is time consuming and puts the patient at severe health risk. After approximately three attempts at intubation the medical procedure will be abandoned. Patients require oxygenation and/or CO2 removal during medical procedures such as anaesthesia. It is difficult to provide the right level of oxygenation and/or CO2 removal. The time to pre-oxygenate and the highest achievable end-tidal oxygen level vary considerably between patients, application method and who is applying it. SUMMARY In accordance with a first aspect of the disclosure, there is provided a system for oxygenating a patient in relation to anaesthesia using high flow gas delivery comprising: a flow source, and a controller for determining oxygenation requirements of the patient before or during anaesthesia. The controller may be adapted to control the flow and/or oxygen concentration of the