Faults in expiratory valves

Resistance of Heidbrink-type expiratory valves.

The minimum resistance of expiratory Heidbrink-type value has been assessed by determining the pressure decrease across the values at a flow rate of 30 litre min--1. The average resistance of 70 valves currently in clinical use was 318 Pa at that flow rate and about 44% had resistances greater than the limit of 294 Pa previously suggested. The resistances obtained in new valves were either simi...

Expiratory valves used for home devices: experimental and clinical comparison.

A bench study followed by a clinical trial were performed to evaluate the mechanical characteristics of five (commercially available) expiratory valves used for home ventilators, as well as the potential clinical impact of differences between these valves. In the in vitro study, expiratory valve resistance was evaluated under unvarying conditions, whereas dynamic behaviour was evaluated by calc...

Classifying Faults Locations in Cable Terminations and Investigation of the Faults Reasons

Cable termination faults are problematic in electrical networks almost always. Technology has solved problems somewhat, but there are many annual reports about damaged cable terminations. For analyzing the problems, faults in two regional electricity companies are studied. At first step, damaged cable terminations are analyzed statistically and grouped according to their problems. Then, some of...

Peak Expiratory Flow Rate in Healthy Children from Tehran

Background: Measuring peak expiratory flow rate has been suggested as an important tool in asthma management by all international guidelines.  Objective: Studies on various populations have shown considerable variations in normal values of peak expiratory flow rate. Since reference standards for Iranian children are not available, the present study was performed to establish these standards. Me...

stress echocardiography in prosthetic heart valves