The Dumping Valve and its Clinical Application
An open reservoir for the collection and evacuation of anaesthetic gases permits leakage to room air. The use of a closed reservoir for the removal of overspill gas from anaesthetic circuits is described. Calibrated gas evacuation is carried out through an ejector flowmeter from the anaesthetic circuit or from a closed reservoir, where the gas is collected via a relief valve. In order to eliminate the risk of high or low pressure in the reservoir employed, a relief valve and a dumping valve is included in the system.
Open Scavenging Systems
A mathematical model was developed to cover the dynamic characteristics of open scavenging systems. The performance of such a device depends on the expiratory tidal volume (VT), the scavenging flow (VS) and the mode of exhalational voliimc build‐up. A widely used open scavenging system was tested by using carbon dioxide in oxygen as a marker gas. Capnography revealed gross turbiilence in the expiratory reservoir, which tends to increase the polluted gas volumrs and loads extra requirements onto the scavenging equipment. Increases in the scavenging flow or the expiratory reservoir volume are the aids in obtaining satisfactory safety margins for pollution‐free scavenging of surplus anaesthetic gases. The tliroretical basis of a new method to determine the expiratory time constant of the respiratory system is also presented.
A bacterial filter for an anesthetic circuit.
ACTERIAL contamination of respiratoryB therapy equipment is a serious and perplexing problem. Anesthesia equipment may be less hazardous; however, it can add foreign bacteria to a tracheobronchial tree. Patients with serious respiratory tract disease contaminate anesthesia equipment and may endanger those subsequently exposed to it. “Nonpathogens,” not usually hazardous, may overwhelm debilitated patients or those with inadequate antibody defenses. Thus some patients must be protected from the flora of an anesthetic circuit, and sometimes the circuit must be protected from the pathogens of a patient’s airway.