cardiovascular
The blood circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. It includes the cardiovascular system, or vascular system, tha ...
test performed by immersing the hand into an ice water container, usually for one minute, and measuring changes in blood pressure and
heart rate
Heart rate (or pulse rate) is the frequency of the heartbeat measured by the number of contractions (beats) of the heart per minute (bpm). The heart rate can vary according to the body's physical needs, including the need to absorb oxygen and excr ...
. These changes relate to
vascular
The blood vessels are the components of the circulatory system that transport blood throughout the human body. These vessels transport blood cells, nutrients, and oxygen to the tissues of the body. They also take waste and carbon dioxide away f ...
response and
pulse
In medicine, a pulse represents the tactile arterial palpation of the cardiac cycle (heartbeat) by trained fingertips. The pulse may be palpated in any place that allows an artery to be compressed near the surface of the body, such as at the n ...
excitability. Some research suggests that the outcome of the cold pressor test can help to predict hypertension in patients; however other studies have failed to confirm this.
Other measures can also be obtained from the cold pressor such as
pain threshold
The threshold of pain or pain threshold is the point along a curve of increasing perception of a stimulus at which pain begins to be felt. It is an entirely subjective phenomenon. A distinction must be maintained between the stimulus (an external ...
and
pain tolerance
Pain tolerance is the maximum level of pain that a person is able to tolerate. Pain tolerance is distinct from pain threshold (the point at which pain begins to be felt). This is done by requiring a participant to place their hand in the cold pressor for as long as they can. Once
pain
Pain is a distressing feeling often caused by intense or damaging stimuli. The International Association for the Study of Pain defines pain as "an unpleasant sensory and emotional experience associated with, or resembling that associated with, ...
is present, they let the researcher know. Once the pain is unbearable, the participant removes his/her hand. This provides a measure of threshold (first feeling pain) and tolerance (total time minus threshold). This method is the most frequently used application of the cold pressor task. Comparable in terms of pain elicitation is the hot water immersion test, the equivalent to the cold pressor using hot water. The hot water immersion test (HIT) is equally capable of triggering a pain response without the confounding of baroreflex activation.
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Physiology
Sensory afferent nerves trigger a systemic sympathetic activation leading to marked
vasoconstriction
Vasoconstriction is the narrowing of the blood vessels resulting from contraction of the muscular wall of the vessels, in particular the large arteries and small arterioles. The process is the opposite of vasodilation, the widening of blood vess ...
. The result is an elevated
pulse pressure
Pulse pressure is the difference between systolic and diastolic blood pressure. It is measured in millimeters of mercury (mmHg). It represents the force that the heart generates each time it contracts. Resting blood pressure is normally appro ...
(normal is 40mm Hg), due to
catecholamine
A catecholamine (; abbreviated CA) is a monoamine neurotransmitter, an organic compound that has a catechol (benzene with two hydroxyl side groups next to each other) and a side-chain amine.
Catechol can be either a free molecule or a su ...
release. This increased pressure fills the ventricle to a greater extent, but
stroke volume
In cardiovascular physiology, stroke volume (SV) is the volume of blood pumped from the left ventricle per beat. Stroke volume is calculated using measurements of ventricle volumes from an echocardiogram and subtracting the volume of the blood i ...