AUTOMATIC VENTILATOR CHALLENGE TO INDUCE SPONTANEOUS BREATHING EFFORTS
This disclosure describes systems and methods for configuring a ventilator for providing automatic, periodic ventilator adjustments to stimulate non-triggering patients to begin initiating spontaneous breathing efforts. Based on studies of respiration, a neural signal stimulating spontaneous breathing efforts is initiated when a patient's arterial partial pressure of carbon dioxide (PaCO 2 ) reaches a certain threshold level, which threshold level may vary from individual to individual. Accordingly, an automatic, periodic ventilator challenge to stimulate spontaneous breathing efforts in a non-triggering patient is provided. An automatic, periodic ventilator challenge refers to an automatic, periodic reduction in the ventilation of a non-triggering patient intended to increase PaCO 2 levels within a clinically-acceptable range. By periodically increasing PaCO 2 levels, the systems and methods disclosed herein seek to achieve the patient's individual PaCO 2 threshold level and, consequently, to evoke a neural signal stimulating spontaneous breathing efforts.
1 . A ventilator-implemented method for stimulating spontaneous breathing efforts when carbon dioxide monitoring is available, the method comprising:
collecting ventilatory data associated with PaCO 2 or a surrogate for PaCO 2 ;
processing the ventilatory data to determine a first target PaCO 2 level;
determining a first reduction in ventilation projected to achieve the first target PaCO 2 level;
providing a first ventilator challenge based on the first reduction in ventilation;
determining whether spontaneous breathing efforts are detected in response to the first ventilator challenge; and
when spontaneous breathing efforts are detected, identifying a successful PaCO 2 level associated with the first ventilator challenge.
2 . The method of claim 1 , wherein the first ventilator challenge is provided until a first period of time expires or a threshold condition is detected.
3 . The method of claim 1 , wherein the first reduction in ventilation comprises a first reduction in minute ventilation, {dot over (V)} E , and wherein the first reduction in {dot over (V)} E comprises a reduction of at least one of: respiratory rate (RR) and tidal volume (V T ).
4 . The method of claim 1 , wherein when spontaneous breathing efforts are not detected, the method further comprises:
identifying the first target PaCO 2 level as an unsuccessful PaCO 2 level; and
determining a second target PaCO 2 level higher than the unsuccessful PaCO 2 level.
5 . The method of claim 4 , further comprising determining a second reduction in ventilation projected to achieve the second target PaCO 2 level.
6 . The method of claim 5 , further comprising determining whether a set interval after the first ventilator challenge has expired.
7 . The method of claim 6 , further comprising:
when the set interval after the first ventilator challenge has expired, providing a second ventilator challenge based on the second reduction in ventilation.
8 . The method of claim 7 , further comprising:
determining whether spontaneous breathing efforts are detected in response to the second ventilator challenge; and
when spontaneous breathing efforts are detected, identifying a successful PaCO 2 level associated with the second ventilator challenge.
9 . A ventilator-implemented method for stimulating spontaneous breathing efforts when carbon dioxide monitoring is not available, the method comprising:
determining a first test percentage for reducing ventilation;
providing a first ventilator challenge based on the first test percentage for reducing ventilation;
determining whether spontaneous breathing efforts are detected in response to the first ventilator challenge; and
when spontaneous breathing efforts are detected, identifying a successful test percentage associated with the first ventilator challenge.
10 . The method of claim 9 , wherein providing the first ventilator challenge comprises reducing minute ventilation, {dot over (V)} E , by the first test percentage, wherein reducing {dot over (V)} E by the first test percentage comprises reducing one of respiratory rate (RR) and tidal volume (V T ) by the first test percentage.
11 . The method of claim 9 , wherein when spontaneous breathing efforts are not detected, the method further comprises:
identifying the first test percentage as an unsuccessful test percentage; and
determining a second test percentage greater than the unsuccessful test percentage for reducing ventilation in a second ventilator challenge.
12 . The method of claim 11 , further comprising:
determining that a set interval after the first ventilator challenge has expired; and
providing a second ventilator challenge by reducing ventilation by the second test percentage.
13 . The method of claim 12 , further comprising:
determining whether spontaneous breathing efforts are detected in response to the second ventilator challenge; and
when spontaneous breathing efforts are detected, identifying a successful test percentage associated with the second ventilator challenge.
14 . The method of claim 9 , wherein the first ventilator challenge is provided for a first period of time.
15 . The method of claim 12 , wherein the second ventilator challenge is provided for a second period of time.
16 . The method of claim 15 , wherein the first period of time and the second period of time are different.
17 . A ventilator processing interface for stimulating spontaneous breathing efforts, comprising:
means for determining a first test percentage for reducing ventilation to stimulate spontaneous breathing efforts;
means for providing a first ventilator challenge based on the first test percentage for reducing ventilation;
means for determining whether spontaneous breathing efforts are detected in response to the first ventilator challenge; and
when spontaneous breathing efforts are detected, means for identifying a successful test percentage associated with the first ventilator challenge.
18 . The ventilator processing interface of claim 17 , wherein the first ventilator challenge is provided for a first period of time.
19 . The ventilator processing interface of claim 17 , wherein the means for providing the first ventilator challenge comprises means for reducing minute ventilation, {dot over (V)} E , by the first test percentage, wherein the means for reducing {dot over (V)} E by the first test percentage comprises means for reducing one of respiratory rate (RR) and tidal volume (V T ) by the first test percentage.
20 . The ventilator processing interface of claim 19 , wherein when spontaneous breathing efforts are not detected, the method further comprises:
means for identifying the first test percentage as an unsuccessful test percentage;
means for determining a second test percentage greater than the unsuccessful test percentage for reducing ventilation in a second ventilator challenge; and
means for providing a second ventilator challenge based on the second test percentage for reducing ventilation.