Final answer:
The application of an ice pack to a client's leg leads to Decreased pain perception as a result of cold-induced vasoconstriction. This reduces blood flow and inflammation, thus decreasing pressure on local pain receptors. C) Decreased pain perception
Step-by-step explanation:
Physiological Effects of Cold Therapy
When a nurse applies an ice pack to a client's leg for a total of 20 minutes, the physiological effect that would occur because of applying cold therapy is C) Decreased pain perception. Cold therapy causes vasoconstriction (narrowing of the blood vessels), which reduces blood flow to the injured area, and in turn, decreases inflammation and swelling. This can lead to a reduction in pain sensation, as the pressure on the local pain receptors is decreased.
Contrary to the effects of cold therapy, vasodilation is a process that happens in response to inflammation and involves the widening of blood vessels. Inflammatory mediators such as histamine cause vasodilation, which increases blood flow to the site of injury, resulting in heat and redness. This process is part of the body's natural response to tissue injury, where increased vascular permeability and blood flow facilitate the recruitment of white blood cells to assist in the healing process. However, during cold therapy, the aim is to dampen this response temporarily to alleviate pain and reduce swelling.
The hunting response is a process of alternating vasoconstriction and vasodilation in extremities exposed to cold, but it typically occurs over a longer period than the application of an ice pack for 20 minutes. Therefore, the immediate response to the cold application is more likely to involve the reduction of blood flow and pain perception rather than vasodilation or increased blood flow.