Perioperative care of the immunocompromised patient

AORN Journal,  March, 2007  by Janice A. Neil

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The immune system defends the body against invading organisms and toxins. It consists of many interdependent cell types that protect the body from bacteria, fungi, parasites, viruses, and tumor cells. The term immunocompromised refers to an immune system in which the ability to resist or fight infections and tumors is subnormal--in other words, a condition in which the immune system is not functioning normally. Immunosuppression is a condition brought about by disease or chemotherapy that leaves an individual highly susceptible to infection. Immunosuppressed patients are immunocompromised.

A patient whose immune system is impaired may be at higher risk for untoward perioperative events; Perioperative nurses must have a basic knowledge of the immune system and understand the root of immune deficiencies in order to institute strategies to protect immunocompromised surgical patients from hypothermia, contamination, and infection. This article provides a basic overview of the immune system, a discussion of common disorders and diseases of the immune system, and a guide for perioperative nurses to use when they care for a patient who is immunocompromised.

ORGANS AND TISSUES OF THE IMMUNE SYSTEM

The term lymphoid refers to the organs and tissues of the immune system that are involved in the growth, development, and dissemination of leukocytes (ie, a type of white blood cell [WBC]). Immune system cells and blood are closely related; both are produced in the bone marrow and both use the bloodstream for transportation. (1) The major components of the immune system are the bone marrow, thymus, peripheral lymphoid organs and tissues, and accessory lymphoid organs and tissues. Each plays a role in the development of B cells and T cells, the two major types of lymphocytes.

BONE MARROW. Bone marrow contains stem cells that use the process of hematopoiesis to develop into two types of cells--lymphocytes and phagocytes. Lymphocytes become either B cells that mature in the bone marrow or T cells that travel to the thymus to mature. Mature cells then are distributed throughout the lymphoid organs, especially the lymph nodes and spleen. Both types of cells have special receptors that respond to different antigens (ie, foreign proteins). The B-cell receptor is an immunoglobin or antibody that either attacks cells directly or directs phagocytes to attack cells. (1)

THYMUS. In the thymus, T cells undergo "education," a process in which they learn to recognize other cells. There are several types of T cells with specific functions. Cytotoxic T cells are capable of killing infected somatic or tumor cells. They kill cells that are infected with viruses or other pathogens or those that are damaged or dysfunctional. Helper T cells (ie, T4 cells) play an important role in establishing and maximizing the capabilities of the immune system. These cells are unusual in that they have no cytotoxic or phagocytic activity. They cannot kill infected host cells or pathogens. These cells are involved in activating and directing other immune cells. Suppressor cells (ie, T8 cells) suppress activation of the immune system and thereby maintain immune system homeostasis and tolerance to itself (ie, preventing the immune system from attacking the body's own cells and tissues). (1)

PERIPHERAL LYMPHOID ORGANS AND TISSUES. Peripheral lymphoid organs and tissues consist of several structures--lymph nodes, lymphatic vessels, and the spleen. Lymph nodes are small, oval-shaped structures located along a network of lymph channels that are most abundant in the neck, axilla, pelvis, and groin. These nodes help remove antigens that circulate in the blood and lymph fluid. Lymphatic vessels contain lymph fluid, consisting of lymphocytes, macrophages, and antigens, that is collected from body tissues as it seeps into the lymphatic vessels. Lymph fluid is transported to the lymph nodes where antigens are processed and killed. The lymph fluid then leaves the node through efferent lymphatic vessels, moves to larger lymph vessels, and finally empties into the superior vena cava. Lymph fluid usually travels through several chains of nodes that prevent organisms in peripheral areas from getting into the central areas. (1)

The spleen is an immunological filter of the blood. It is made up of B cells, T cells, macrophages, dendritic cells, natural killer cells, and red blood cells. It has several functions. Phagocytes within the spleen engulf and break down worn out or damaged red blood cells. The spleen also filters and removes bacteria and other antigens. Interactions of splenic phagocytes with lymphocytes serve to initiate immune responses. The spleen also stores blood and platelets. (1)

ACCESSORY LYMPHOID ORGANS AND TISSUES. The accessory lymphoid organs and tissues include the tonsils; adenoids; appendix; and Peyer's patches (ie, collections of lymphatic tissue within submucosa of the small intestine). The accessory lymphoid organs and tissues are located in areas that come in contact with food and air where microbial numbers may be high,and they remove foreign debris in the same manner as lymph nodes. (1)