APPARATUS FOR RESPIRATORY SUPPORT AND NON-INVASIVE DETECTION OF ALVEOLAR DERECRUITMENT FOR PATIENTS SUFFERING FROM RESPIRATORY FAILURE

• US 20090272381A1
• Filed: 09/11/2007
• Published: 11/05/2009
• Est. Priority Date: 09/14/2006
• Status: Active Grant

• Current Assignee: Politecnico di Milano
• Original Assignee: Politecnico di Milano
• Inventors: Dellaca, Raffaele, Pedotti, Antonio, Aliverti, Andrea
• Granted Patent: US 8,689,787 B2
• Time in Patent Office: Days
• US Class Current: 128/204.230
• CPC Class Codes: A61B 5/085 Measuring impedance of respiratory organs or lung elasticity
• CPC Class Codes: A61M 16/0006 with means for creating vibrations in patients' airways
• CPC Class Codes: A61M 16/0051 with alarm devices
• CPC Class Codes: A61M 16/024 including calculation means, e.g. using a processor
• 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 2016/0036 in the breathing tube and used in both inspiratory and expiratory phase
• CPC Class Codes: A61M 2230/005 Parameter used as control input for the apparatus
• CPC Class Codes: A61M 2230/65 Impedance, e.g. conductivity, capacity

Abstract

There is described an apparatus (1) for respiratory support and non-invasive detection of alveolar derecruitment for patients suffering from respiratory failure. Such an apparatus (1) generally comprises a mechanical ventilator (3) for inspiration/expiration functions and means (15) allowing to impose an additional periodic pressure component (Pstim) having a higher frequency than the spectral content of the inspiration/expiration pressure component (Presp). There are provided computing means (12) to obtain the inspiratory average reactance (Xrs) of the respiratory system of the patient (2) as the positive end-expiratory pressure (PEEP) varies, in order to detect the presence of alveolar derecruitment. There is also described a procedure allowing to obtain an optimal positive end-expiratory pressure.

Claims

1. An apparatus (1) for respiratory support and non-invasive detection of alveolar derecruitment for patients (2) suffering from respiratory failure, said apparatus (1) comprising means (3) for carrying out respiratory functions and comprising conduits (5, 6, 7, 20, 21) for the passage of air from and to the airways of a patient (2), and further comprising transducers of pressure (9, 10) to electric signals, transducers of flow (8) to electric signals and computing means (12, 412) for processing said electric signals so as to obtain a value of the inspiratory reactance (Xrs) indicative of the state of pulmonary derecruitment, which corresponds to a point of maximum respiratory reactance.

2. An apparatus according to claim 1, wherein said means (3) for carrying out respiratory functions comprise a mechanical ventilator (3) allowing imposition of inspiration/expiration functions, a settable positive end-expiratory pressure (PEEP) being provided.

3. An apparatus according to claim 2, wherein said pressure component (P^stim) has at least a frequency and amplitude harmonic suitable to-obtain said inspiratory reactance (Xrs) which is periodic with a period longer than the harmonic content of the respiratory frequency of said patient (2), said apparatus ventilating said patient by inspiration/expiration.

4. An apparatus according to claim 1, wherein said means (3) allowing carrying out the respiratory functions comprise a high frequency oscillating ventilator allowing imposition of a periodic pressure having a frequency and an amplitude suitable to allow obtaining said inspiratory reactance.

5. An apparatus according to claim 4, wherein the continuous distension pressure of said high frequency ventilator is settable.

6. An apparatus according to claim 1 wherein said computing means (12) automatically controls the settings of said means (3) allowing carrying out the respiratory functions, said computing means (12) being provided with algorithms adapted to determine the maximum value of inspiratory reactance (Xrs).

7. An apparatus according claim 1 wherein said means (15) allowing imposition of said additional pressure component (P^stim) comprise a speaker (15) fitted to at least one of said conduits (5).

8. An apparatus according to claim 1 which comprises a low pass filter obtained by means of a narrow and long tube (16).

9. An apparatus according to claim 7 wherein said computing means (12) are connected, by means of an amplifier (14), to said speaker (15) so as to control the inspiration/expiration pressure component (P^resp).

10. An apparatus according to claim 1 wherein said means (15) allowing imposition of said additional pressure component (P^stim) comprise a modulating valve fitted to at least one of said conduits (5).

11-15. -15. (canceled)

16. A procedure for the detection of the optimal ventilation parameters in the course of artificial respiration by means (3) adapted to carry out the respiratory functions, comprising the following phases setting the positive end-expiratory pressure parameters to a value near zero CmH2O (100), pressure (P) and flow (Flow) sampling and computing of the inspiratory reactance (Xrs) for increasing values of positive end-expiratory pressure SEEP) pressure (P) and flow (Flow) sampling and computing of the inspiratory reactance (Xrs) for decreasing values of positive end-expiratory pressure (PEEP), verifying derecruitment, identifying a positive end-expiratory pressure (PEEP) (110) corresponding to a desired point of respiratory reactance.

17. A procedure according to claim 16, wherein said desired point of respiratory reactance is the point of maximum respiratory reactance.

24. The procedure of claim 16, wherein said desired point of respiratory reactance is the point of maximum inspiratory reactance.

25. The procedure according to claim 16, which comprises repeating previous phases and identifying a positive end-expiratory pressure (PEEP) (110) corresponding to a desired point of respiratory reactance.

18-23. -23. (canceled)