Objective Under noninvasive positive pressure ventilation, in view of inconvenient operations in human airway, and avoiding the interference of spontaneous breathing and the necessary leakage flow, the method for dynamic online monitoring of the respiratory resistance (R) and compliance (C) was studied.Methods At the end of expiration, when the exhaled flow was 0, relative to the expiration positive airway pressure (EPAP), a step-dropped pressure was produced with the amplitude Δp and hold time Δt. Under this dropped pressure, a short-time discharged flow was generated from the lung, and the discharged flow was applied to calculate the R and C. In addition, a respiratory model was developed in MATLAB to simulate the breaths of normal adult, acute respiratory distress syndrome (ARDS) patient and chronic obstructive pulmonary disease (COPD) patient. A serial of simulation experiments were carried out for obtaining data and verification.Results The calculated R and C from simulation for normal adult, ARDS patient, COPD patient, deviated from the actual value by 1.60% and -1.60%, 1.21% and -1.19%, -12.53% and 14.32%, respectively.Conclusions The proposed algorithm is practicable and feasible for calculating the R and C. The simulation results are beneficial for studying and realizing the intelligent ventilation and proportional assist ventilation in respirator.

Objective To compare biomechanical properties between the anatomical clavicle plate and the reconstructed clavicle plate, and investigate the influence of pre-bending or repeated bending process on biomechanical properties of the reconstructed clavicle plate, so as to provide biomechanical evidence for treating midshaft clavicle fracture in clinic. Methods The reconstructed clavicle plate was bent by 1, 2, 3, 5 times respectively based on shape of the anatomical clavicle plate. The biomechanical differences in anatomical plate group, reconstructed plate group and pre-bending plate group were compared by static compression test. Results The fixation stiffness and strength of the anatomical plate were better than those of the reconstructed plate. There was no significant difference in stiffness and strength between the anatomical plate group and one-time bending group. Pre-bending had a great effect on mechanical properties of the clavicle plate, and stiffness and strength of the clavicle plate were obviously improved after one-time bending. The mechanical properties of the clavicle plate were obviously reduced by bending of the clavicle plate after one-time bending. Conclusions The stiffness and strength of the anatomical plate and one-time bending plate are higher than those of the normal reconstructed plate. It is recommended that surgeons should perform bending appropriately according to the patient’s clavicle anatomy when using the reconstructed clavicle plate for fracture fixation, and minimize the number of repeated bending to maintain stiffness and strength of the clavicle plate.