Anesthesia Key

A direct current (DC) is the unidirectional flow of electrons. The current flow may vary and fall towards zero, but as long as the direction of electron flow does not…

Carbonic acid is formed by the reaction between carbon dioxide and water. 2. Carbonic acid reacts with sodium hydroxide to form sodium carbonate. This step also produces water and heat….

The logarithmic scale produces a 10-fold change in hydrogen ion concentration per unit change in pH. Modern blood gas machines rapidly measure several variables including pH, pCO2, PO2, oxyhaemoglobin concentration…

Oxygen molecules diffuse across the membrane from the sample gas into the sensor, and are reduced to hydroxyl ions at the cathode. The hydroxyl ions then migrate to and oxidise…

Absorbance is a dimensionless number; 0 indicates no absorbance of light, while 1 indicates 90% of light has been absorbed. Absorbance >1 is uncommon, as Beer–Lambert’s law ceases to be…

Venturi systems utilise the Bernoulli principle to create a negative pressure. They are driven by compressed gas, but are limited by weak flow rates and loud noise. Applied science What…

Cardiac impulses begin in the right atrium at the sino-atrial node. The wave of depolarisation spreads through both atria to the atrioventricular node. Here it travels via the bundle of…

At room temperature and one atmosphere pressure, most anaesthetic agents exist in their liquid form. The vaporising chamber is fully saturated with anaesthetic vapour. Wicks help to increase the surface…

The highest energy level is the most unstable state, and electrons quickly decay by releasing energy in the form of heat to a slightly lower energy level called the metastable…

Wavelength is the distance between two points of maximum compression or rarefaction. The frequency of a wave is the number of wavelengths per second expressed as hertz (Hz). High-frequency sounds…