A Respiratory Mechanical Parameters Estimation Technology Based on Extended Least Squares

Abstract

Respiratory mechanical parameters of ventilated patients are usually referred in the respiratory diagnosis and treatment. However, the effectiveness of the modern estimation methods is limited. To estimate the overall breathing resistance, overall respiratory compliance, and residual volume simultaneously, a new mathematical model of mechanical ventilation system was proposed. Furthermore, to improve the estimation accuracy, the noise model of mechanical ventilation system was taken into consideration. Based on the mathematical model, a respiratory mechanical parameters estimation method based on extended least squares (ELS) algorithm was derived. Finally, to test the respiratory mechanical parameters estimation method, it was studied experimentally and numerically, and it was approved that the proposed method is effective to estimate the three respiratory mechanical parameters simultaneously and precisely. The estimated values of the parameters can be adopted in the clinical practice. The study provides a new method to estimate respiratory mechanical parameters.

Dimensionless simulation study on mechanical in-exsufflation secretion clearance systems with a volume-controlled ventilation function

“…As shown in Figures 19 and 34, strength of secretion clearance has little impact on the pressure in lung both in the PCS system and in the VCS system. As shown in Figures 20,22,35, and 36, when strength of secretion clearance increases, negative bottom pressure in tract declines, a 25% decrease of dimensionless pressure of secretion clearance (from 0.9378 to 0.9474) in the PCS brings about a nearly 13% decrease of dimensionless bottom pressure in tract, while a 20% increase of dimensionless volume flow of secretion clearance (from 1.0 to 1.2) in the VCS system leads to a nearly 52% decrease of dimensionless bottom pressure in tract. It is obvious that strength of secretion clearance has more effect on bottom pressure in tract in the VCS system.…”

“…As shown in Figures 12 and 29, effective area of lung has an little impact on pressure in lung both in the PCS system and in the VCS system. As shown in Figures 13,15,[16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32], when effective area of lung becomes lower, peak pressure in tract gets higher and bottom pressure gets lower; meanwhile, pressure in the plateau time keeps fixed. In addition, bottom pressure declines more rapidly in the VCS system than that in the PCS system; in the VCS system, a 42% decrease of dimensionless effective area (from 0.454 to 0.647) leads to a nearly 52% decrease of dimensionless negative bottom pressure in tract, while in the PCS system, a 42% decrease of dimensionless effective area (from 0.454 to 0.647) leads to a nearly 35% decrease of dimensionless negative bottom pressure in tract.…”

“…Initially, bacteria breeds easily in patients' respiratory system with accumulation of secretions, which may bring about pulmonary infection. [10][11][12][13][14][15][16][17][18][19][20][21][22] Furthermore, hypoventilation, 1 respiratory failure, and other relevant diseases may be caused by secretion in airway. [23][24][25][26][27] What is more, the most common disease is ventilator-associated pneumonia (VAP) in mechanical ventilation, whose incidence rate is about 68% and mortality rate is 50%-70%, [28][29][30][31][32] respectively.…”

“…33,34 In-line inexsufflation (IL-IE) verified to reduce risk of VAP effectively is widely applied clinically. [15][16][17][18][19][20][21][22][35][36][37] However, because of the device cannot connect with ventilator, persistent airway collapse may be caused by the IL-IE. 38,39 In this article, aiming at the disadvantages of existing secretion clearance technologies, pressure-controlled secretion clearance (PCS) system and volume-controlled secretion clearance (VCS) system, two MI-E secretion clearance systems with a volume-controlled ventilation (VCV) function, had been proposed.…”