	US 12,274,827 B2
	Method and apparatus for determining a regional compliance of a lung during spontaneous respiration
Peter Kremeier, Karlsruhe (DE)
Assigned to LOEWENSTEIN MEDICAL TECHNOLOGY S.A, Luxembourg (LU)
Filed by Loewenstein Medical Technology S.A., Luxembourg (LU)
Filed on Feb. 5, 2021, as Appl. No. 17/168,268.
Claims priority of application No. 102020103145.9 (DE), filed on Feb. 7, 2020.
Prior Publication US 2021/0244901 A1, Aug. 12, 2021
Int. Cl. A61M 16/00 (2006.01); A61B 5/0536 (2021.01); A61B 5/085 (2006.01)

CPC A61M 16/024 (2017.08) [A61B 5/0536 (2013.01); A61B 5/085 (2013.01); A61M 16/0057 (2013.01); A61M 2205/502 (2013.01); A61M 2230/65 (2013.01)]

20 Claims

1. A method for determining a regional compliance C.REG_iof a lung, wherein the method comprises:

capturing an electrical impedance distribution along at least one two-dimensional section through a human thorax by a device for electrical impedance tomography (EIT),

triggering a ventilation maneuver and determining the electrical impedance distribution from a start of inspiration to an end of expiration and measuring a compliance of the entire lung or measuring a surrogate for the compliance of the entire lung,

wherein the compliance corresponds to the highest impedance (pixel density) of the EIT, and

determining the regional compliance by dividing an ascertained impedance among a number of lung regions and assigning the impedance to the lung regions;

or comprises, in case of determining a regional compliance C.REG; of a lung during spontaneous respiration:

determining a lung compliance value C.M by triggering an inspiration maneuver and either measuring a compliance of the entire lung or a surrogate for the compliance of the entire lung,

capturing an electrical impedance distribution along at least one two-dimensional section through a human thorax by a device for electrical impedance tomography,

dividing a captured electrical impedance distribution at different times into a multiplicity of EIT pixels,

determining an end-expiratory electrical impedance Z.EXSP for each EIT pixel and an end-inspiratory electrical impedance Z.INSP for each EIT pixel,

determining an impedance difference ΔZ for each EIT pixel by virtue of calculating a difference between Z.INSP and Z.EXSP,

providing a plurality of impedance value ranges and assigning the EIT pixels to the impedance value ranges based on a respective impedance difference ΔZ of the EIT pixels,

determining the regional compliance C.REG_ifor specific EIT pixels, which are assigned to an impedance value range i, based on a frequency distribution of all EIT pixels among the impedance value ranges and based on the lung compliance value C.M,

and wherein the regional compliance C.REG_iis determined as per

wherein the EIT pixels are assigned to m impedance value ranges, NPX_nis a number of EIT pixels which are assigned to an n-th impedance value range of the m impedance value ranges, W_i.UB is an upper bound of the impedance value range i and W_n.UB is an upper bound of the n-th impedance value range of the m impedance value ranges.