The role of regional anaesthesia in patient outcome: thoracic and abdominal surgeries

ANSYS-MATLAB co-simulation of mucus flow distribution and clearance effectiveness of a new simulated cough device

Coughing is an irritable reaction that protects the respiratory system from infection and improves mucus clearance. However, for the patients who cannot cough autonomously, an assisted cough device is essential for mucus clearance. Considering the low efficiency of current assisted cough devices, a new simulated cough device based on the pneumatic system is proposed in this paper. Given the uncertainty of airflow rates necessary to clear mucus from airways, the computational fluid dynamics Eulerian wall film model and cough efficiency (CE) were used in this study to simulate the cough process and evaluate cough effectiveness. The Ansys-Matlab co-simulation model was set up and verified through experimental studies using Newtonian fluids. Next, model simulations were performed using non-Newtonian fluids, and peak cough flow (PCF) and PCF duration time were analyzed to determine their influence on mucus clearance. CE growth rate (λ) was calculated to reflect the CE variation trend. From the numerical simulation results, we find that CE rises as PCF increases while the growth rate trends to slow as PCF increases; when PCF changes from 60 to 360 L/min, CE changes from 3.2% to 51.5% which is approximately 16 times the initial value. Meanwhile, keeping a long PCF duration time could greatly improve CE under the same cough expired volume and PCF. The results indicated that increasing the PCF and PCF duration time can improve the efficiency of mucus clearance. This paper provides a new approach and a research direction for control strategy in simulated cough devices for airway mucus clearance.

Perioperative management of a patient undergoing a novel mini-invasive percutaneous transcatheter left ventricular reconstruction procedure

Survivors of myocardial infarction might have residual damage and higher risks of developing heart failure. This increasing complication encompasses up to 45% of all infarcts. As anesthesiologists we will have to perform anesthesia more frequently in patients with such challenging medical history schedule to undergo mini-invasive surgical procedures. We present the case of a 51-year-old man with severe heart failure post-myocardial infarction with multiple sclerosis undergoing a novel percutaneous transcatheter ventricular reconstruction via a left mini-thoracotomy. To guide the surgeon during the intervention we used a real-time 3D echocardiography, enlightening the fact that guidance is crucial for that kind of procedure. To lower postoperative pain and the inflammatory response we have administered successfully intravenous lidocaine, indicating that it is possible to avoid regional anesthesia in patients with multiple sclerosis scheduled for mini-invasive left ventricular reconstruction requiring a mini-thoracotomy.

DIMENSIONLESS OPTIMIZATION STUDY ON A VENTILATOR WITH SECRETION CLEARANCE FUNCTION

To improve the efficiency and safety of secretion clearance, a novel ventilator (SC ventilator) with an automatic secretion clearance function is proposed. To lay a foundation for the optimization of the SC ventilator, the basic mathematical model of the ventilation system is derived. By selecting the appropriate reference values, the basic mathematical model is transformed to a dimensionless expression for simulation. Through the experimental and simulation study on the SC ventilation system, it can be concluded that: firstly, the mathematical model is proved to be authentic and reliable. Secondly, the influences of the three key parameters on the dynamics of the SC ventilation system are carried out. Last, to guarantee the pressure in the lung is higher than the expiratory positive airway pressure, the dimensionless minimum pressure in the flexible tube should be set higher than 0.9164, the dimensionless suction pressure should be set higher than 0.79.