Term	Explanation
Adrenergic agonist	A drug that stimulates a response from the adrenergic receptors.
Adrenergic receptors (or adrenoceptors)	A class of G protein‐coupled receptors that are targets of the catecholamines, especially norepinephrine (noradrenaline) and epinephrine (adrenaline). There are three types of adrenergic receptors: alpha, beta 1, and beta 2. Alpha‐receptors are found in the arteries and when they are stimulated by epinephrine or norepinephrine, the arteries constrict. This increases the blood pressure and the blood flow returning to the heart. Beta 1 receptors are located in the heart and when they are stimulated, they increase the heart rate and increase the heart's strength of contraction or contractility. Beta 2 receptors are found in the lungs and the arteries of the skeletal muscles. When these receptors are stimulated, they increase the diameter of the airways to let more air in and out during breathing and they widen the vessels of the skeletal muscles so they can receive the increased blood flow produced by stimulating the alpha and beta 1 receptors.
Afferent	Conducted inwards or towards something.
Anti‐cholinergics	A class of drugs that affects the muscles around the bronchi (large airways). When the lungs are irritated, these bands of muscle can tighten, making the bronchi narrower; anticholinergics work by stopping the muscles from tightening.
Anxiolytic	Used to reduce anxiety.
Bolus	Administration of a discrete amount of medication, drug or other compound in order to raise its concentration in blood to an effective level.
Buccal	Relating to cheek
Chemoreceptor	A sensory nerve cell or sense organ, as of smell or taste, that responds to chemical stimuli.
Corollary discharge	A copy of a motor command that is sent to the muscles to produce a movement; this copy or corollary does not produce any movement itself but instead is directed to other regions of the brain to inform them of the impending movement.
Correlation co‐efficient	This number (between ‐1 & 1) measures the strength of association between two variables.
Cross‐over trial	A type of clinical trial comparing two or more treatments where when participants complete the course of one treatment they are switched to another. For example, in a comparison of treatments A and B, half the participants are randomly allocated to receive them in the order A, B and half to receive them in the order B, A. One problem with this design is that the effects of the first treatment may carry over into the period when the second is given.
Dichotomous data	Data with two possible categories only, e.g. yes/no, male/female, etc.
Dyspnoea	Difficult or laboured breathing.
Efferent	Conducted outwards or away from something.
Forest plot	A forest plot displays effect estimates and confidence intervals for both individual studies and meta‐analyses
Funnel plot	A funnel plot is a simple scatter plot of the intervention effect estimates from individual studies against some measure of each study’s size or precision.
Half‐life	The time required for any specified property (e.g. the concentration of a substance in the body) to decrease by half.
Hypercapnia	Also known as hypercarbia; a condition where there is an increased amount of carbon dioxide, the waste product of breathing, in the blood.
Hypoxia	A deficiency in the amount of oxygen reaching the tissues.
Impute	The process of replacing missing data with substituted values
Palliation	A kind of care that eases symptoms of disease, even though it can't cure them.
Pharmacotherapy	The treatment of diseases with drugs.
Quasi‐RCT	A trial using a method of allocating participants to different treatments that is not truly random, for example, allocation by date of birth, day of the week, medical record number, month of the year, or the order in which participants are included in the study.
Sublingual	Situated or applied under the tongue.