Average volume ventilation

• US 6,920,875 B1
• Filed: 06/02/2000
• Issued: 07/26/2005
• Est. Priority Date: 06/15/1999
• Status: Expired due to Term

• Current Assignee: RIC INVESTMENTS LLC (Respironics Incorporated)
• Original Assignee: Respironics Incorporated
• Inventors: Hill, Peter D., Kissel, Michael H., Frank, John
• Primary Examiner(s): Dawson, Glenn K.
• Assistant Examiner(s): Erezo, Darwin P.
• Application Number:
  US09/586,054
• Time in Patent Office: 1,880 Days
• Field of Search: 128/204.26, 128/204.18, 128/204.21, 128/204.23, 128/204.22
• US Class Current: 128/204.18
• CPC Class Codes: A61M 16/026 specially adapted for predicting, e.g. for determining an information representative of a flow limitation during a ventilation cycle by using a root square technique or a regression analysis
• CPC Class Codes: A61M 2016/0021 with a proportional output signal, e.g. from a thermistor
• CPC Class Codes: A61M 2016/0027 pressure meter
• CPC Class Codes: A61M 2016/0039 in the inspiratory circuit
• CPC Class Codes: A61M 2205/15 Detection of leaks
• CPC Class Codes: A61M 2230/60 Muscle strain, i.e. measured on the user

Abstract

A ventilator supplies a plurality of volumes of fluid to a patient during a like plurality of inhalations by the patient. Each volume of fluid is supplied at an inspiratory positive airway pressure during a corresponding inhalation by the patient. A volume of fluid received by the patient is determined for each of the plurality of inhalations by the patient and an average volume of fluid received by the patient during each of the plurality of inhalations is determined. The average volume of fluid received by the patient during each inhalation is compared to a predetermined target volume and the inspiratory positive airway pressure each volume of fluid is supplied to the patient is adjusted as a function of the comparison.

Claims

1. A method of adjusting a volume of a fluid supplied to a patient, the method comprising the steps of:

(a) supplying a plurality of volumes of fluid to a patient during a like plurality of inspiratory phases of a respiratory cycle of such a patient, each volume of fluid being supplied at an inspiratory positive airway pressure during a corresponding inspiratory phase;

(b) determining, for each inspiratory phase, a tidal volume of fluid received by such a patient;

(c) determining an average tidal volume of fluid received by such a patient from the volumes of fluid received by such a patient during the plurality of inspiratory phases, wherein the average tidal volume is determined irrespective of a period of time during which the plurality of inspiratory phases occur;

(d) comparing the average tidal volume to a predetermined target tidal volume;

(e) adjusting the inspiratory positive airway pressure based on the comparison;

(f) comparing a current inspiratory positive airway pressure to a maximum inspiratory positive airway pressure and a minimum inspiratory positive airway pressure; and

(g) preventing adjusting of the inspiratory positive airway pressure in step (e) if one of (1) the current inspiratory positive airway pressure is greater than the maximum inspiratory positive airway pressure and (2) the current inspiratory positive airway pressure is less than the minimum inspiratory positive airway pressure.

2. An apparatus for supplying fluid to a patient, the apparatus comprising:

a pressure generating system adapted to provide a flow of fluid at one of a variable pressure and a variable flow;

a patient circuit operatively coupled to the pressure generating system to deliver the flow of fluid to a patient;

an interface device operatively coupled to the patient circuit to communicate the flow of fluid to an airway of a patient;

at least one sensor operatively coupled to one of the pressure generating system, the patient circuit, and the interface device to detect a parameter indicative of a volume of fluid delivered to such a patient; and

a controller operatively coupled to the sensor and the pressure generating system, wherein the controller;

(a) determines, for each inspiratory phase of a respiratory cycle of such a patient, a tidal volume of fluid received by such a patient based on the parameter indicative of a volume of fluid delivered to such a patient provided by the sensor;

(b) determines an average tidal volume of fluid received by such a patient over a plurality of inspiratory phases, wherein the average tidal volume is determined irrespective of a period of time during which the plurality of inspiratory phases occur;

(c) compares the average tidal volume of fluid received by such a patient to a predetermined target tidal volume;

(d) causes the pressure generating system to adjust pressure, a rate of flow of fluid output thereby, or both based on the comparison; and

(e) prevents adjusting of the pressure or the rate of flow of fluid output by the pressure generating system if (1) the current pressure is greater than a predetermined maximum pressure or (2) the current pressure is less than a predetermined minimum pressure.

3. An apparatus for supplying fluid to a patient, the apparatus comprising:

pressure generating means for providing a flow of fluid at one of a variable pressure and a variable flow rate;

delivering means for delivering the flow of fluid to a patient;

interfacing means for communicating the flow of fluid to an airway of a patient;

sensing means for sensing a parameter indicative of a volume of fluid delivered to such a patient; and

processing means for;

(a) determining, for each inspiratory phase of a respiratory cycle of such a patient, a tidal volume of fluid received by such a patient based on the parameter indicative of a volume of fluid delivered to such a patient provided by the sensing means;

(b) determining an average tidal volume of fluid received by such a patient over a plurality of inspiratory phases, wherein the average tidal volume is determined irrespective of a period of time during which the plurality of inspiratory phases occur;

(c) comparing the average tidal volume of fluid received by such a patient to a predetermined target tidal volume;

(d) causing the pressure generating means to adjust a pressure, a rate of flow of fluid output thereby, or both based on the comparison; and

(e) preventing adjusting of the pressure or the rate of flow of fluid output by the pressure generating system if (1) the current pressure is greater than a predetermined maximum pressure or (2) the current pressure is less than a predetermined minimum pressure.

4. An apparatus for adjusting a volume of a fluid supplied to a patient, the apparatus comprising:

supplying means for supplying a plurality of volumes of fluid to a patient during a like plurality of inhalations by such a patient, with each volume of fluid supplied at an inspiratory positive airway pressure during a corresponding inspiratory phase;

tidal volume determining means for determining, for each inspiratory phase, a tidal volume of fluid received by such a patient;

average tidal volume determining means for determining an average tidal volume of fluid received by such a patient from the tidal volumes of fluid received by such a patient during the plurality of inspiratory phases, wherein the average tidal volume is determined irrespective of a period of time during which the plurality of inspiratory phases occur;

comparing means for comparing the average tidal volume to a predetermined target tidal volume;

adjusting means for adjusting the inspiratory positive airway pressure based on the comparison;

comparing means for comparing a current inspiratory positive airway pressure to a maximum inspiratory positive airway pressure and a minimum inspiratory positive airway pressure; and

preventing means for preventing adjusting of the inspiratory positive airway pressure if (1) the current inspiratory positive airway pressure is greater than the maximum inspiratory positive airway pressure or (2) the current inspiratory positive airway pressure is less than the minimum inspiratory positive airway pressure.

5. An apparatus for supplying a desired volume of a fluid to a patient, the apparatus comprising:

supplying means for supplying a first volume of fluid to a patient at a first inspiratory positive airway pressure;

determining means for determining, for the first volume of fluid supplied to such a patient, a first tidal volume of fluid received by such a patient, wherein the supplying means supplies a second volume of fluid to such a patient at the first inspiratory positive airway pressure, and wherein the determining means determines, for the second volume of fluid supplied to such a patient, a second tidal volume of fluid received by such a patient;

averaging means for determining, based on the first and the second tidal volumes of fluid received by such a patient, a first average tidal volume of fluid received by such a patient, wherein the first average tidal volume is determined irrespective of a period of time during which the plurality of inspiratory phases occur;

comparing means for comparing the first average tidal volume to a predetermined target tidal volume;

adjusting means for adjusting the first inspiratory positive airway pressure to a second inspiratory positive airway pressure based on the comparison of the first average volume to the predetermined target volume;

comparing means for comparing a current inspiratory positive airway pressure to a maximum inspiratory positive airway pressure and a minimum inspiratory positive airway pressure; and

preventing means for preventing adjusting of the inspiratory positive airway pressure if (1) the current inspiratory positive airway pressure is greater than the maximum inspiratory positive airway pressure or (2) the current inspiratory positive airway pressure is less than the minimum inspiratory positive airway pressure.