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General Index
The
GALE ENCYCLOPEDIA
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NURSING AND
ALLIED HEALTH
STAFF
Kristine Krapp, Coordinating Senior Editor
Christine B. Jeryan, Managing Editor
Deirdre S. Blanchfield, Associate Editor (Manuscript Coordination)
Melissa C. McDade, Associate Editor (Photos and Illustrations)
Stacey L. Blachford, Associate Editor
Kate Kretschmann, Assistant Editor
Donna Olendorf, Senior Editor
Ryan Thomason, Assistant Editor
Mark Springer, Technical Specialist
Andrea Lopeman, Programmer/Analyst
Barbara Yarrow, Manager,
Imaging and Multimedia Content
Robyn V. Young, Project Manager, Imaging and Multimedia Content
Randy Bassett, Imaging Supervisor
Dan Newell, Imaging Specialist
Pamela A. Reed, Coordinator, Imaging and Multimedia Content
Maria Franklin, Permissions Manager
Margaret A. Chamberlain, Permissions Specialist
Kenn Zorn, Product Manager
Michelle DiMercurio, Senior Art Director
Cynthia Baldwin, Senior Art Director
Mary Beth Trimper, Manager, Composition, and Electronic Prepress
Evi Seoud, Assistant Manager, Composition Purchasing, and Electronic Prepress
Dorothy Maki, Manufacturing Manager
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Since this page cannot legibly accommodate all copyright notices, the acknowledgments constitute an extension of the copyright notice. While every effort has been made to ensure the reliability of the infor-mation presented in this publication, the Gale Group neither guarantees the accuracy of the data contained herein nor assumes any responsibil-ity for errors, omissions or discrepancies. The Gale Group accepts no payment for listing, and inclusion in the publication of any organiza-tion, agency, instituorganiza-tion, publicaorganiza-tion, service, or individual does not imply endorsement of the editor or publisher. Errors brought to the attention of the publisher and verified to the satisfaction of the publish-er will be corrected in future editions.
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This publication is a creative work fully protected by all applicable copyright laws, as well as by misappropriation, trade secret, unfair competition, and other applicable laws. The authors and editor of this work have added value to the underlying factual material herein through one or more of the following: unique and original selec-tion, coordinaselec-tion, expression, arrangement, and classification of the information.
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Copyright © 2002 Gale Group 27500 Drake Road
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All rights reserved including the right of reproduction in whole or in part in any form.
ISBN 0-7876-4934-1 (set) 0-7876-4937-6 (Vol. 3) 0-7876-4935-X (Vol. 1) 0-7876-4938-4 (Vol. 4) 0-7876-4936-8 (Vol. 2) 0-7876-4939-2 (Vol. 5) Printed in Canada
10 9 8 7 6 5 4 3 2 1
Library of Congress Cataloging-in-Publication Data The Gale encyclopedia of nursing and allied health / Kristine Krapp, editor.
p. cm.
Includes bibliographical references and index. ISBN 0-7876-4934-1 (set : hardcover : alk. paper)
ISBN 0-7876-4935-X (v. 1 : alk. paper) — ISBN 0-7876-4936-8 (v.2 : alk. paper) —
ISBN 0-7876-4937-6 (v. 3 : alk. paper) — ISBN0-7876-4938-4 (v. 4 : alk. paper) — ISBN 0-7876-4939-2 (v. 5 : alk. paper) 1. Nursing Care—Encyclopedias—English. 2. Allied Health Personnel—Encyclopedias—English.
3. Nursing—Encyclopedias—English. WY 13 G151 2002] RT21 .G353 2002
610.73'03—dc21
CONTENTS
Introduction
. . . .vii
Advisory Board
. . . .ix
Contributors
. . . .xi
Entries
Volume 1: A-C. . . .1
Volume 2: D-H. . . .
641
Volume 3: I-O. . . .
1237
Volume 4: P-S. . . .
1797
Volume 5: T-Z. . . .
2383
Appendix of Nursing and Allied Health
Organizations
. . . .2663
PLEASE READ—IMPORTANT INFORMATION
The Gale Encyclopedia of Nursing and Allied Health
is a medical reference product designed to inform and educate readers about a wide variety of diseases, treat-ments, tests and procedures, health issues, human biolo-gy, and nursing and allied health professions. The Gale Group believes the product to be comprehensive, but not necessarily definitive. While the Gale Group has made substantial efforts to provide information that is accurate, comprehensive, and up-to-date, the Gale Group makes no
INTRODUCTION
The Gale Encyclopedia of Nursing and Allied Health
is a unique and invaluable source of information for the nursing or allied health student. This collection of over 850 entries provides in-depth coverage of specific dis-eases and disorders, tests and procedures, equipment and tools, body systems, nursing and allied health profes-sions, and current health issues. This book is designed to fill a gap between health information designed for laypeople and that provided for medical professionals, which may be too complicated for the beginning student to understand. The encyclopedia does use medical termi-nology, but explains it in a way that students can under-stand.
SCOPE
The Gale Encyclopedia of Nursing and Allied Health
covers a wide variety of topics relevant to the nursing or allied health student. Subjects covered include those important to students intending to become biomedical equipment technologists, dental hygienists, dieteticians, health care administrators, medical technologists/clinical laboratory sciencists, registered and licensed practical nurses, nurse anesthetists, nurse practitioners, nurse mid-wives, occupational therapists, optometrists, pharmacy technicians, physical therapists, radiologic technologists, and speech-language therapists. The encyclopedia also covers information on related general medical topics, classes of medication, mental health, public health, and human biology. Entries follow a standardized format that provides information at a glance. Rubrics include:
Diseases/Disorders
Definition Description
Causes and symptoms Diagnosis
Treatment Prognosis
Health care team roles Prevention
Resources Key terms
Tests/Procedures
Definition Purpose Precautions Description Preparation Aftercare Complications Results
Health care team roles Resources
Key terms
Equipment/Tools
Definition Purpose Description Operation Maintenance
Health care team roles Training
Resources Key terms
Human biology/Body systems
Definition Description Function
Role in human health
Common diseases and disorders Resources
G A L E E N C Y C L O P E D I A O F N U R S I N G A N D A L L I E D H E A LT H V I I I
Nursing and allied health professions
Definition Description Work settings
Education and training
Advanced education and training Future outlook
Resources Key terms
Current health issues
Definition Description Viewpoints
Professional implications Resources
Key terms
INCLUSION CRITERIA
A preliminary list of topics was compiled from a wide variety of sources, including nursing and allied health textbooks, general medical encyclopedias, and consumer health guides. The advisory board, composed of advanced practice nurses, allied health professionals, health educators, and medical doctors, evaluated the top-ics and made suggestions for inclusion. Final selection of topics to include was made by the advisory board in con-junction with the Gale editor.
ABOUT THE CONTRIBUTORS
The essays were compiled by experienced medical writers, including physicians, pharmacists, nurses, and allied health care professionals. The advisers reviewed the completed essays to ensure that they are appropriate, up-to-date, and medically accurate.
HOW TO USE THIS BOOK
The Gale Encyclopedia of Nursing and Allied Health
has been designed with ready reference in mind.
• Straight alphabetical arrangement of topics allows users to locate information quickly.
• Bold-faced terms within entries direct the reader to related articles.
• Cross-referencesplaced throughout the encyclopedia direct readers from alternate names and related topics to entries.
• A list of Key termsis provided where appropriate to define terms or concepts that may be unfamiliar to the student.
• The Resources section directs readers to additional sources of medical information on a topic.
• Valuable contact informationfor medical, nursing, and allied health organizations is included with each entry. An Appendix of Nursing and Allied Health organizations in the back matter contains an extensive list of organizations arranged by subject.
• A comprehensive general indexguides readers to sig-nificant topics mentioned in the text.
GRAPHICS
The Gale Encyclopedia of Nursing and Allied Health
is enhanced by over 400 black and white photos and illus-trations, as well as over 50 tables.
ACKNOWLEDGMENTS
The editor would like to express appreciation to all of the nursing and allied health professionals who wrote, reviewed, and copyedited entries for the Gale Encyclopedia of Nursing and Allied Health.
Cover photos were reproduced by the permission of Delmar Publishers, Inc., Custom Medical Photos, and the Gale Group.
ADVISORY BOARD
Dr. Isaac Bankman Principal Scientist
Imaging and Laser Systems Section Johns Hopkins Applied Physics Laboratory Laurel, Maryland
Martha G. Bountress, M.S., CCC-SLP/A Clinical Instructor
Speech-Language Pathology and Audiology Old Dominion University
Norfolk, Virginia
Michele Leonardi Darby
Eminent Scholar, University Professor Graduate Program Director
School of Dental Hygiene Old Dominion University Norfolk, Virginia
Dr. Susan J. Gromacki
Lecturer in Ophthalmology and Visual Sciences University of Michigan Medical School Ann Arbor, Michigan
Dr. John E. Hall
Guyton Professor and Chair
Department of Physiology and Biophysics University of Mississippi Medical Center Jackson, Mississippi
Lisa F. Harper, B.S.D.H., M.P.H., R.D., L.D. Assistant Professor
Baylor College of Dentistry Dallas, Texas
Robert Harr, M.S. MT (ASCP) Associate Professor and Chair
Department of Public and Allied Health Bowling Green State University Bowling Green, Ohio
Dr. Gregory M. Karst Associate Professor
Division of Physical Therapy Education University of Nebraska Medical Center Omaha, Nebraska
Debra A. Kosko, R.N., M.N., FNP-C Instructor, Faculty Practice
School of Nursing, Department of Medicine Johns Hopkins University
Baltimore, Maryland
Timothy E. Moore, Ph.D., C Psych Professor of Psychology
Glendon College York University
Toronto, Ontario, Canada
Anne Nichols, C.R.N.P.
Coordinator, Family Nurse Practitioner Program School of Nursing
Widener University Chester, Pennsylvania
Judith B. Paquet, R.N.
Medical Communications Specialist Paquet Associates
Clementon, New Jersey
Lee A. Shratter, M.D. Radiologist
Healthcare Safety and Medical Consultant Kentfield, California
Linda Wheeler, C.N.M., Ed.D. Associate Professor
School of Nursing
Oregon Health and Science University Portland, Oregon
CONTRIBUTORS
Lisa Maria Andres, M.S., C.G.C San Jose, California
Greg Annussek New York, New York
Maia Appleby
Boynton Beach, Florida
Bill Asenjo, M.S., C.R.C. Iowa City, Iowa
Lori Ann Beck, R.N., M.S.N., F.N.P.-C. Berkley, Michigan
Mary Bekker
Willow Grove, Pennsylvania
Linda K. Bennington, R.N.C., M.S.N., C.N.S. Virginia Beach, Virginia
Kenneth J. Berniker, M.D. El Cerrio, California
Mark A. Best
Cleveland Heights, Ohio
Dean Andrew Bielanowski, R.N., B.Nurs.(QUT) Rochedale S., Brisbane, Australia
Carole Birdsall, R.N. A.N.P. Ed.D. New York, New York
Bethanne Black Buford, Georgia
Maggie Boleyn, R.N., B.S.N. Oak Park, Michigan
Barbara Boughton El Cerrito, California
Patricia L. Bounds, Ph.D. Zurich, Switzerland
Mary Boyle, Ph.D., C.C.C.-S.L.P., B.C.-N.C.D. Lincoln Park, New Jersey
Rachael Tripi Brandt, M.S. Gettysburg, Pennsylvania
Peggy Elaine Browning Olney, Texas
Susan Joanne Cadwallader Cedarburg, Wisconsin
Barbara M. Chandler Sacramento, California
Linda Chrisman Oakland, California
Rhonda Cloos, R.N. Austin, Texas
L. Lee Culvert Alna, Massachusetts
Tish Davidson Fremont, California
Lori De Milto
Sicklerville, New Jersey
Victoria E. DeMoranville Lakeville, Massachusetts
Janine Diebel, R.N. Gaylord, Michigan
Stéphanie Islane Dionne Ann Arbor, Michigan
J. Paul Dow, Jr. Kansas City, Missouri
Douglas Dupler Boulder, Colorado
Lorraine K. Ehresman Northfield, Quebec, Canada
G A L E E N C Y C L O P E D I A O F N U R S I N G A N D A L L I E D H E A LT H X I I
Diane Fanucchi-Faulkner, C.M.T., C.C.R.A. Oceano, California
Janis O. Flores Sebastopol, Florida
Paula Ford-Martin Chaplin, Minnesota
Janie F. Franz
Grand Forks, North Dakota
Sallie Boineau Freeman, Ph.D. Atlanta, Georgia
Rebecca Frey, Ph.D. New Haven, Connecticut
Lisa M. Gourley Bowling Green, Ohio
Meghan M. Gourley Germantown, Maryland
Jill Ilene Granger, M.S. Ann Arbor, Michigan
Elliot Greene, M.A. Silver Spring, Maryland
Stephen John Hage, A.A.A.S., R.T.(R), F.A.H.R.A. Chatsworth, California
Clare Hanrahan
Asheville, North Carolina
Robert Harr
Bowling Green, Ohio
Daniel J. Harvey Wilmington, Delaware
Katherine Hauswirth, A.P.R.N. Deep River, Connecticut
David L. Helwig
London, Ontario, Canada
Lisette Hilton Boca Raton, Florida
René A. Jackson, R.N. Port Charlotte, Florida
Nadine M. Jacobson, R.N. Takoma Park, Maryland
Randi B. Jenkins New York, New York
Michelle L. Johnson, M.S., J.D. Portland, Oregon
Paul A. Johnson San Marcos, California
Linda D. Jones, B.A., P.B.T.(A.S.C.P.) Asheboro, New York
Crystal Heather Kaczkowski, M.Sc. Dorval, Quebec, Canada
Beth Kapes Bay Village, Ohio
Monique Laberge, Ph.D. Philadelphia, Pennsylvania
Aliene S. Linwood, B.S.N., R.N., D.P.A., F.A.C.H.E. Athens, Ohio
Jennifer Lee Losey, R.N. Madison Heights, Michigan
Liz Marshall Columbus, Ohio
Mary Elizabeth Martelli, R.N., B.S. Sebastian, Florida
Jacqueline N. Martin, M.S. Albrightsville, Pennsylvania
Sally C. McFarlane-Parrott Mason, Michigan
Beverly G. Miller, M.T.(A.S.C.P.) Charlotte, North Carolina
Christine Miner Minderovic, B.S., R.T., R.D.M.S. Ann Arbor, Michigan
Mark A. Mitchell, M.D. Bothell, Washington
Susan M. Mockus, Ph.D. Seattle, Washington
Timothy E. Moore, Ph.D. Toronto, Ontario, Canada
Nancy J. Nordenson Minneapolis, Minnesota
Erika J. Norris
Oak Harbor, Washington
Debra Novograd, B.S., R.T.(R)(M) Royal Oak, Michigan
Marianne F. O’Connor, M.T., M.P.H. Farmington Hills, Michigan
Carole Osborne-Sheets Poway, California
Cindy F. Ovard, R.D.A Spring Valley, California
Patience Paradox
Bainbridge Island, Washington
Deborah Eileen Parker, R.N. Lakewood, Washington
Genevieve Pham-Kanter Chicago, Illinois
Jane E. Phillips, Ph.D. Chapel Hill, North Carolina
Pamella A. Phillips Bowling Green, Ohio
Elaine R. Proseus, M.B.A./T.M., B.S.R.T., R.T.(R) Farmington Hills, Michigan
Ann Quigley
New York, New York
Esther Csapo Rastegari, R.N., B.S.N., Ed.M. Holbrook, Massachusetts
Anastasia Marie Raymer, Ph.D. Norfolk, Virginia
Martha S. Reilly, O.D. Madison, Wisconsin
Linda Richards, R.D., C.H.E.S. Flagstaff, Arizona
Toni Rizzo
Salt Lake City, Utah
Nancy Ross-Flanigan Belleville, Michigan
Mark Damian Rossi, Ph.D, P.T., C.S.C.S. Pembroke Pines, Florida
Kausalya Santhanam Branford, Connecticut
Denise L. Schmutte, Ph.D. Shoreline, Washington
Joan M. Schonbeck
Marlborough, Massachusetts
Kathleen Scogna Baltimore, Maryland
Cathy Hester Seckman, R.D.H. Calcutta, Ohio
Jennifer E. Sisk, M.A. Havertown, Pennsylvania
Patricia Skinner Amman, Jordan
Genevieve Slomski New Britain, Connecticut
Bryan Ronain Smith Cincinnati, Ohio
Allison Joan Spiwak, B.S., C.C.P. Gahanna, Ohio
Lorraine T. Steefel Morganville, New Jersey
Margaret A. Stockley, R.G.N. Boxborough, Massachusetts
Amy Loerch Strumolo Bloomfield Hills, Michigan
Liz Swain
San Diego, California
Deanna M. Swartout-Corbeil, R.N. Thompsons Station, Tennessee
Peggy Campbell Torpey, M.P.T. Royal Oak, Michigan
Mai Tran, Pharm.D. Troy, Michigan
Carol A. Turkington Lancaster, Pennsylvania
Judith Turner, D.V.M. Sandy, Utah
Samuel D. Uretsky, Pharm.D. Wantagh, New York
Michele R. Webb Overland Park, Kansas
Ken R. Wells
Laguna Hills, California
Barbara Wexler, M.P.H. Chatsworth, California
Gayle G. Wilkins, R.N., B.S.N., O.C.N. Willow Park, Texas
Jennifer F. Wilson Haddonfield, New Jersey
Angela Woodward Madison, Wisconsin
Jennifer Wurges
Rochester Hills, Michigan
A
Abdominal thrust
see
Heimlich maneuver
Abdominal ultrasound
DefinitionAbdominal ultrasound uses high frequency sound waves to produce two-dimensional images of the body’s soft tissues, which are used for a variety of clinical appli-cations, including diagnosis and guidance of treatment procedures. Ultrasound does not use ionizing radiation to produce images, and in comparison to other diag-nostic imaging modalities, it is low cost, safe, fast, and versatile.
Purpose
Abdominal ultrasound is used in the hospital radiol-ogy department and emergency department, as well as in physician offices for a number of clinical applications. Ultrasound has a great advantage over x-ray imaging technologies in that it does not damage tissues with ion-izing radiation. Ultrasound is also generally far better than plain x-rays at distinguishing the subtle variations of soft tissue structures, and can be used in any of several modes, depending on the area of interest.
As an imaging tool, abdominal ultrasound generally is indicated for patients afflicted with chronic or acute abdominal pain; abdominal trauma; an obvious or sus-pected abdominal mass; symptoms of liverdisease, pan-creatic disease, gallstones, spleen disease, kidney disease and urinary blockage; or symptoms of an abdominal aor-tic aneurysm.
Specifically:
• Abdominal pain. Whether acute or chronic, pain can signal a serious problem—from organ malfunction or injury to the presence of malignant growths.
Ultrasound scanning can help doctors quickly sort through potential causes when presented with general or ambiguous symptoms. All of the major abdominal organs can be studied for signs of disease that appear as changes in size, shape, and internal structure.
• Abdominal trauma. After a serious accident, such as a car crash or a fall, internal bleeding from injured abdominal organs is often the most serious threat to survival. Neither the injuries nor the bleeding may be immediately apparent. Ultrasound is very useful as an initial scan when abdominal trauma is suspected, and it can be used to pinpoint the location, cause, and severi-ty of hemorrhaging. In the case of puncture wounds, from a bullet for example, ultrasound can locate the foreign object and provide a preliminary survey of the damage. (CT scansare sometimes used in trauma settings.)
• Abdominal mass. Abnormal growths—tumors, cysts, abscesses, scar tissue, and accessory organs—can be located and tentatively identified with ultrasound. In particular, potentially malignant solid tumors can be distinguished from benign fluid-filled cysts. Masses and malformations in any organ or part of the abdomen can be found.
• Liver disease. The types and underlying causes of liver disease are numerous, though jaundice tends to be a general symptom. Ultrasound can differentiate between many of the types and causes of liver malfunction, and is particularly good at identifying obstruction of the bile ducts and cirrhosis, which is characterized by abnormal fibrous growths and reduced bloodflow. • Pancreatic disease. Inflammation and malformation of
the pancreas are readily identified by ultrasound, as are pancreatic stones (calculi), which can disrupt prop-er functioning.
gall-G A L E E N C Y C L O P E D I A O F N U R S I N gall-G A N D A L L I E D H E A LT H 2
bladder and liver to the intestines. Gallstones are read-ily identifiable with ultrasound.
• Spleen disease. The spleen is particularly prone to injury during abdominal trauma. It may also become painfully inflamed when infected or cancerous.
• Kidney disease. The kidneysare also prone to traumat-ic injury and are the organs most likely to form calculi, which can block the flow of urine and cause further systemic problems. A variety of diseases causing dis-tinct changes in kidney morphology can also lead to complete kidney failure. Ultrasound imaging has proven extremely useful in diagnosing kidney disor-ders, including blockage or obstruction.
• Abdominal aortic aneurysm. This is a bulging weak spot in the abdominal aorta, which supplies blood directly from the heartto the entire lower body. A rup-tured aortic aneurysm is imminently life-threatening. However, it can be readily identified and monitored with ultrasound before acute complications result.
•Appendicitis. Ultrasound is useful in diagnosing appendicitis, which causes abdominal pain.
Ultrasound technology can also be used for treat-ment purposes, most frequently as a visual aid during surgical procedures—such as guiding needle placement to drain fluid from a cyst, or to guide biopsies.
Precautions
Ultrasound waves of appropriate frequency and intensity are not known to cause or aggravate any med-ical condition.
The value of ultrasound imaging as a medical tool, however, depends greatly on the quality of the equipment used and the skill of the medical personnel operating it. More accurate results are obtained when ultrasound is performed by a clinician skilled in sonography. Basic ultrasound equipment is relatively inexpensive to obtain, and any physician with the equipment can perform the procedure whether specifically trained in ultrasound scanning and interpretation or not. Patients should not hesitate to verify the credentials of technologists and physicians performing ultrasound scanning, as well as the quality of the equipment used and the benefits of the proposed procedure.
In cases where ultrasound is used as a treatment tool, patients should educate themselves about the proposed procedure with the help of their doctors—as is appropri-ate before any surgical procedure. Also, any abdominal ultrasound procedure, diagnostic or therapeutic, may be hampered by a patient’s body type or other factors, such as the presence of excessive bowel gas (which is opaque
to ultrasound). In particular, very obese people are often not good candidates for abdominal ultrasound.
Description
Ultrasound includes all sound waves above the fre-quency of human hearing—about 20 thousand hertz, or cycles per second. Medical ultrasound generally uses fre-quencies between one and 10 megahertz (1-10 MHz). Higher frequency ultrasound waves produce more detailed images, but are also more readily absorbed and so cannot penetrate as deeply into the body. Abdominal ultrasound imaging is generally performed at frequencies between 2-5 MHz.
An ultrasound scanner consists of two parts: the trans-ducer and the data processing unit. The transtrans-ducer both produces the sound waves that penetrate the body and receives the reflected echoes. Transducers are built around piezoelectric ceramic chips. (Piezoelectric refers to elec-tricity that is produced when you put pressure on certain crystals such as quartz.) These ceramic chips react to elec-tric pulses by producing sound waves (they are transmit-ting waves) and react to sound waves by producing elec-tric pulses (receiving). Bursts of high-frequency elecelec-tric pulses supplied to the transducer cause it to produce the scanning sound waves. The transducer then receives the returning echoes, translates them back into electric pulses, and sends them to the data processing unit—a computer that organizes the data into an image on a television screen.
Because sound waves travel through all the body’s tissues at nearly the same speed—about 3,400 miles per hour—the microseconds it takes for each echo to be received can be plotted on the screen as a distance into the body. The relative strength of each echo, a function of the specific tissue or organ boundary that produced it, can be plotted as a point of varying brightness. In this way, the echoes are translated into an image.
Four different modes of ultrasound are used in med-ical imaging:
• A-mode. This is the simplest type of ultrasound in which a single transducer scans a line through the body with the echoes plotted on screen as a function of depth. This method is used to measure distances within the body and the size of internal organs.
• B-mode. In B-mode ultrasound, a linear array of trans-ducers simultaneously scans a plane through the body that can be viewed as a two-dimensional image on screen.
• M-Mode. The M stands for motion. A rapid sequence of B-mode scans whose images follow each other in sequence on screen enables doctors to see and measure range of motion, as the organ boundaries that produce reflections move relative to the probe. M-mode
sound has been put to particular use in studying heart motion.
• Doppler mode. Doppler ultrasonographyincludes the capability of accurately measuring velocities of moving
material, such as blood in arteries and veins. The prin-ciple is the same as that used in radar guns that measure the speed of a car on the highway. Doppler capability is most often combined with B-mode scanning to produce
Abdominal ultrasound
Doppler—The Doppler effect refers to the apparent change in frequency of sound wave echoes return-ing to a stationary source from a movreturn-ing target. If the object is moving toward the source, the fre-quency increases; if the object is moving away, the frequency decreases. The size of this frequency shift can be used to compute the object’s speed— be it a car on the road or blood in an artery. The Doppler effect holds true for all types of radiation, not just sound.
Frequency—Sound, whether traveling through air or the human body, produces vibrations—mole-cules bouncing into each other—as the shock wave travels along. The frequency of a sound is the num-ber of vibrations per second. Within the audible range, frequency means pitch—the higher the fre-quency, the higher a sound’s pitch.
Ionizing radiation—Radiation that can damage liv-ing tissue by disruptliv-ing and destroyliv-ing individual cells at the molecular level. All types of nuclear radiation—x rays, gamma rays and beta rays—are potentially ionizing. Sound waves physically vibrate the material through which they pass, but do not ionize it.
Jaundice—A condition that results in a yellow tint to the skin, eyes and body fluids. Bile retention in the liver, gallbladder and pancreas is the immediate cause, but the underlying cause could be as simple as obstruction of the common bile duct by a gall-stone or as serious as pancreatic cancer. Ultra-sound can distinguish between these conditions.
Malignant—The term literally means growing worse and resisting treatment. It is used as a syn-onym for cancerous and connotes a harmful condi-tion that generally is life-threatening.
Morphology—Literally, the study of form. In medi-cine, morphology refers to the size, shape, and structure rather than the function of a given organ. As a diagnostic imaging technique, ultrasound facilitates the recognition of abnormal morpholo-gies as symptoms of underlying conditions. Accessory organ—A lump of tissue adjacent to an
organ that is similar to it, but which serves no important purpose, if functional at all. While not necessarily harmful, such organs can cause prob-lems if they grow too large or become cancerous. Benign—In medical usage, benign is the opposite of malignant. It describes an abnormal growth that is stable, treatable, and generally not life-threatening.
Biopsy—The surgical removal and analysis of a tis-sue sample for diagnostic purposes. Usually, the term refers to the collection and analysis of tissue from a suspected tumor to establish malignancy. Calculus—Any type of hard concretion (stone) in the body, but usually found in the gallbladder, pan-creas, and kidneys. Calculi (pl.) are formed by the accumulation of excess mineral salts and other organic material such as blood or mucous. They can cause problems by lodging in and obstructing the proper flow of fluids, such as bile to the intes-tines or urine to the bladder.
Cirrhosis—A chronic liver disease characterized by the degeneration of proper functioning—jaundice is often an accompanying symptom. Causes of cir-rhosis include alcoholism, metabolic diseases, syphilis, and congestive heart disease.
Common bile duct—The branching passage through which bile—a necessary digestive enzyme—travels from the liver and gallbladder into the small intestine. Digestive enzymes from the pancreas also enter the intestines through the com-mon bile duct.
Computed tomography scan (CT scan)—A special-ized type of x-ray imaging that uses highly focused and relatively low energy radiation to produce detailed two-dimensional images of soft tissue structures, particularly the brain. CT scans are the chief competitor to ultrasound and can yield high-er quality images not disrupted by bone or gas. They are, however, more cumbersome, time con-suming and expensive to perform, and they use ionizing radiation.
G A L E E N C Y C L O P E D I A O F N U R S I N G A N D A L L I E D H E A LT H 4
images of blood vesselsfrom which blood flow can be directly measured. This technique is used extensively to investigate valve defects, arteriosclerosis, and hyper-tension, particularly in the heart, but also in the abdom-inal aorta and the portal vein of the liver.
The actual procedure for a patient undergoing an abdominal ultrasound is relatively simple, regardless of the type of scan or its purpose. Fasting for at least eight hours prior to the procedure ensures that the stomachis empty and as small as possible, and that the intestines and bowels are relatively inactive. This also helps the gallbladder become more visible. Prior to scanning, an acoustic gel is applied to the skin of the patient’s abdomen to allow the ultrasound probe to glide easily across the skin and also to better transmit and receive ultrasonic pulses. The probe is moved around the abdomen’s surface to obtain different views of the target areas. The patient will likely be asked to change posi-tions from side to side and to hold the breath as necessary to obtain the desired views. Usually, a scan will take from 20 to 45 minutes, depending on the patient’s condi-tion and anatomical area being scanned.
Ultrasound scanners are available in different con-figurations, with different scanning features. Portable units, which weigh only a few pounds and can be carried by hand, are available for bedside use, office use, or use outside the hospital, such as at sporting events and in ambulances. Portable scanners range in cost from $10,000 to $50,000. Mobile ultrasound scanners, which can be pushed to the patient bedside and between hospi-tal departments, are the most common comfiguration and range in cost from $100,000 to over $250,000, depend-ing on the scanndepend-ing features purchased.
Preparation
A patient undergoing abdominal ultrasound will be advised by the physician about what to expect and how to prepare. As mentioned above, preparations generally include fasting.
Aftercare
In general, no aftercare related to the abdominal ultrasound procedure itself is required. Discomfort dur-ing the procedure is minimal.
Complications
Properly performed, ultrasound imaging is virtually without risk or side effects. Some patients report feeling a slight tingling and/or warmth while being scanned, but most feel nothing at all.
Results
As a diagnostic imaging technique, a normal abdom-inal ultrasound is one that indicates the absence of the sus-pected condition that prompted the scan. For example, symptoms such as abdominal pain radiating to the back suggest the possibility of, among other things, an abdom-inal aortic aneurysm. An ultrasound scan that indicates the absence of an aneurysm would rule out this life-threaten-ing condition and point to other, less serious causes.
Because abdominal ultrasound imaging is generally undertaken to confirm a suspected condition, the results of a scan often will confirm the diagnosis, be it kidney stones, cirrhosis of the liver, or an aortic aneurysm. At that point, appropriate medical treatment as prescribed by a patient’s physician is in order.
Health care team roles
Ultrasound scanning should be performed by a reg-istered and trained ultrasonographer, either a technologist and/or a physician (radiologist, obstetrician/gynecolo-gist). Ultrasound scanning in the emergency department may be performed by an emergency medicine physician, who should have appropriate training and experience in ultrasonography.
Resources BOOKS
Dendy, P.P., Heaton, B. Physics for Diagnostic Radiology.2nd ed. Philadelphia: Institute of Physics Publishing, 1999. Hall, Rebecca. The Ultrasonic Handbook: Clinical, etiologic
and pathologic implications of sonographic findings. Philadelphia: Lippincott, 1993.
Abdominal ultrasound
An ultrasound screen shows a patient’s kidney.
Kevles, Bettyann Holtzmann. Naked to the Bone: Medical imaging in the twentieth century.New Brunswick, New Jersey: Rutgers University Press, 1997.
Zaret, Barry L., ed. The Patient’s Guide to Medical Tests. Boston: Houghton Mifflin Company, 1997.
PERIODICALS
Freundlich, Naomi. “Ultrasound: What’s Wrong with this Picture?” Business Week(15 September 1997): 84-85. Kuhn, M., Bonnin, R.L.L., Davey, M.J., Rowland, J.L.,
Langlois, S. “Emergency Department Ultrasound Scanning for Abdodminal Aortic Aneurysm: Accessible, Accurate, Advantageous. Annals of Emergency Medicine. (September 2000) 36(3):219-223.
Sisk, Jennifer. “Ultrasound in the Emergency Department: Toward a Standard of Care.” Radiology Today(June 4, 2001) 2(1):8-10.
ORGANIZATIONS
American College of Radiology. 1891 Preston White Drive, Reston, VA 20191-4397. (800)227-5463.
<http://www.acr.org>.
American Institute of Ultrasound in Medicine. 14750 Sweitzer Lane, Suite 100, Laurel, MD 20707-5906. (301) 498-4100. <http://www.aium.org>.
American Registry of Diagnostic Medical Sonographers. 600 Jefferson Plaza, Suite 360, Rockville, MD 20852-1150. (800) 541-9754. <http://www.ardms.org>.
American Society of Radiologic Technologists (ASRT). 15000 Central Avenue SE, Albuquerque, NM 87123-2778. (800) 444-2778. <http://www.asrt.org>.
Radiological Society of North America. 820 Jorie Boulevard, Oak Brook, IL 60523-2251. (630) 571-2670.
<http://www.rsna.org>.
Society of Diagnostic Medical Sonography. 12770 Coit Road, Suite 708, Dallas, TX 75251-1319. (972) 239-7367. <http://www.sdms.org>.
Jennifer E. Sisk, M.A.
ABO blood typing
see
Type and screen
Abrasions
see
Wounds
Abruptio placentae
see
Placental abruption
Abscess
DefinitionAn abscess is an enclosed collection of liquefied tis-sue, known as pus, somewhere in the body. It is the result of the body’s defensive reaction to foreign material.
Description
There are two types of abscesses, septic and sterile. Most abscesses are septic, which means that they are the result of an infection. Septic abscesses can occur any-where in the body. Only bacteria and the body’s immune responseare required. In response to the invad-ing bacteria, white bloodcells gather at the infected site and begin producing chemicals called enzymes that attack the bacteria by first marking and then digesting it. These enzymes kill the bacteria and break them down into small pieces that can travel in the circulatory system prior to being eliminated from the body. Unfortunately, these chemicals also digest body tissues. In most cases, bacteria produce similar chemicals. The result is a thick, yellow liquid—pus—containing dead bacteria, digested tissue, white blood cells, and enzymes.
An abscess is the last stage of a tissue infection that begins with a process called inflammation. Initially, as invading bacteria activate the body’s immune system, several events occur:
• Blood flow to the area increases.
• The temperature of the area increases due to the increased blood supply.
• The area swells due to the accumulation of water, blood, and other liquids.
• It turns red.
• It hurts, due to irritation from the swelling and the chemical activity.
These four signs—heat, swelling, redness, and pain—characterize inflammation.
As the process progresses, the tissue begins to turn to liquid, and an abscess forms. It is the nature of an abscess to spread as the chemical digestion liquefies more and more tissue. Furthermore, the spreading follows the path of least resistance, commonly, the tissue that is most eas-ily digested. A good example is an abscess just beneath the skin. It most easily continues along immediately beneath the surface rather than traveling up through the outermost layer or down through deeper structures where it could drain its toxic contents. The contents of an abscess can also leak into the general circulation and pro-duce symptoms just like any other infection. These include chills, fever, aching, and general discomfort.
Sterile abscesses are sometimes a milder form of the same process caused not by bacteria but by non-living irritants such as drugs. If an injected drug such as peni-cillin is not absorbed, it stays where it is injected and may cause enough irritation to generate a sterile abscess. Such an abscess is sterile because there is no infection involved. Sterile abscesses are quite likely to turn into
G A L E E N C Y C L O P E D I A O F N U R S I N G A N D A L L I E D H E A LT H 6
hard, solid lumps as they scar, rather than remaining pockets of pus.
Causes and symptoms
Many different agents cause abscesses. The most common are the pus-forming (pyogenic) bacteria such as
Staphylococcus aureus, which is a very common cause of abscesses under the skin. Abscesses near the large bowel, particularly around the anus, may be caused by any of the numerous bacteria found within the large bowel. Brain abscesses and liver abscesses can be caused by any organism that can travel there through the blood stream. Bacteria, amoebae, and certain fungi can travel in this fashion. Abscesses in other parts of the body are caused by organisms that normally inhabit nearby structures or that infect them. Some common causes of specific abscesses are:
• skin abscesses by normal skin flora
• dental and throat abscesses by mouth flora
• lung abscesses by normal airway flora, bacteria that cause pneumoniaor tuberculosis
• abdominal and anal abscesses by normal bowel flora
Specific types of abscesses
Listed below are some of the more common and important abscesses.
• Carbuncles and other boils. Skin oil glands (sebaceous glands) on the back or the back of the neck are the ones usually infected. The most commonly involved bacteria is Staphylococcus aureus. Acne is a similar condition involving sebaceous glands on the face and back.
• Pilonidal cyst. Many people have as a birth defect a tiny opening in the skin just above the anus. Fecal bacteria can enter this opening, causing an infection and subse-quent abscess.
• Retropharyngeal, parapharyngeal, peritonsillar abscess. As a result of throat infections such as strep throatand tonsillitis, bacteria can invade the deeper tissues of the throat and cause an abscess. These abscesses can com-promise swallowing and even breathing.
• Lung abscess. During or after pneumonia, whether it’s due to bacteria [common pneumonia], tuberculosis, fungi, parasites, or other bacteria, abscesses can devel-op as a complication.
• Liver abscess. Bacteria or amoeba from the intestines can spread through the blood to the liver and cause abscesses.
• Psoas abscess. Deep in the back of the abdomen, on either side of the lumbar spine, lie the psoas muscles. They flex the hips. An abscess can develop in one of these muscles, usually when it spreads from the appen-dix, the large bowel, or the fallopian tubes.
Diagnosis
The common findings of inflammation—heat, red-ness, swelling, and pain—easily identify superficial abscesses. Abscesses in other places may produce only generalized symptoms such as fever and discomfort. If an individual’s symptoms and the results of a physical examinationdo not help, a physician may have to resort to a battery of tests to locate the site of an abscess. Usually something in the initial evaluation directs the search. Recent or chronic disease in an organ suggests it may be the site of an abscess. Dysfunction of an organ or system, for instance seizures or altered bowel function, may provide the clue. Painand tenderness on physical examination are common findings. Sometimes a deep abscess will eat a small channel (sinus) to the surface and begin leaking pus. A sterile abscess may cause only a painful lump deep in the buttock where a shot was given.
Abscess
K E Y T E R M S
Cellulitis—Inflammation of tissue due to infection.
Enzyme—Any of a number of protein chemicals that can initiate chemical reactions at body tem-perature.
Fallopian tubes—Part of the internal female anatomy that carries eggs from the ovaries to the uterus.
Flora—Living inhabitants of a region or area. Pyogenic—Capable of generating pus.
Strep-tococcus, Staphocococcus, and bowel bacteria
are the primary pyogenic organisms.
Sebaceous glands—Tiny structures in the skin that produce oil (sebum). If they become plugged, sebum collects inside and forms a nurturing place for germs to grow.
Septicemia—The spread of an infectious agent throughout the body by means of the blood stream.
Treatment
Since skin is very resistant to the spread of infection, it acts as a barrier, often keeping the toxic chemicals of an abscess from escaping the body on their own. Thus, the pus must be drained from the abscess by a physician. The surgeon determines when the abscess is ready for drainage and opens a path to the outside, allowing the pus to escape. Ordinarily, the body handles the remaining infection, sometimes with the help of antibiotics or other drugs. The surgeon may leave a drain (a piece of cloth or rubber) in the abscess cavity to prevent it from closing before all the pus has drained out.
Alternative treatment
If an abscess is directly beneath the skin, it will be slowly working its way through the skin as it is more rap-idly working its way elsewhere. Since chemicals work faster at higher temperatures, applications of hot com-presses to the skin over the abscess will hasten the diges-tion of the skin and eventually result in its break down and spontaneous release of pus. This treatment is best reserved for smaller abscesses in less sensitive areas of the body such as limbs, trunk, and back of the neck. It is also useful for all superficial abscesses in their very early stages. It will “ripen” them.
Contrast hydrotherapy, alternating hot and cold compresses, can also help assist the body in resorption of the abscess. There are two homeopathic remedies that work to rebalance the body in relation to abscess forma-tion, Silica and Hepar sulphuris. In cases of septic abscesses, bentonite clay packs (bentonite clay and a small amount of Hydrastispowder) can be used to draw an infection from the area.
Prognosis
Once an abscess is properly drained, the prognosis is excellent for the condition itself. The reason for the abscess (other diseases an individual has) will determine the overall outcome. If, on the other hand, an abscess ruptures into neighboring areas or permits the infectious agent to spill into the bloodstream, serious or fatal con-sequences are likely. Abscesses in and around the nasal sinuses, face, ears, and scalp may work their way into the brain. Abscesses within an abdominal organ such as the liver may rupture into the abdominal cavity. In either case, the result is life threatening. Blood poisoningis a term commonly used to describe an infection that has spilled into the blood stream and spread throughout the body from a localized origin. Blood poisoning, known to physicians as septicemia, is also life threatening.
Of special note, abscesses in the hand are more seri-ous than they might appear. Due to the intricate structure and the overriding importance of the hand, any hand infection must be treated promptly and competently.
Health care team roles
First aid providers may unknowingly initiate an abscess by using inappropriate or incorrect techniques. A physician, surgeon, physician’s assistant, or nurse practi-tioner usually diagnoses the presence of an abscess. Radiologists and laboratory personnel may assist in the process of establishing a diagnosis. A physician, surgeon, physician’s assistant, or nurse practitioner usually drains an abscess. Nurses provide supportive care, dress the wound, and educate patients about caring for the result-ing wound. Occasionally, a physical therapist may be needed to recover lost function.
Prevention
Infections that are treated early with heat (if superfi-cial) or antibiotics will often resolve without the forma-tion of an abscess. It is even better to avoid infecforma-tions altogether by taking prompt care of open injuries, partic-ularly puncture wounds. Bites are the most dangerous of all, even more so because they often occur on the hand.
Resources BOOKS
Balistreri, William. “Liver abscess.” In Nelson Textbook of Pediatrics, 16th ed., edited by Richard E. Behrman et al., Philadelphia, Saunders, 2000, 1212.
Chesney, Russell W. “Brain abscess.” In Nelson Textbook of Pediatrics, 16th ed., edited by Richard E. Behrman et al., Philadelphia, Saunders, 2000, 1857-1858.
Abscess
An amoebic abscess caused by Entameoba histolytica.
G A L E E N C Y C L O P E D I A O F N U R S I N G A N D A L L I E D H E A LT H 8
Finegold, Sydney M. “Lung abscess.” In Cecil Textbook of Medicine, 21st ed.,edited by Goldman, Lee and Bennett, J. Claude. Philadelphia: W.B. Saunders, 2000, 439-442. Herendeen, Neil E and Szilagy, Peter G. “Peritonsillar
abscess.” In Nelson Textbook of Pediatrics, 16th ed., edit-ed by Richard E. Behrman et al., Philadelphia, Saunders, 2000, 1266-1267.
Scheld, W. Michael. “Bacterial meningitis, brain abscess, and other suppurative intracranial infections.” In Harrison’s Principles of Internal Medicine, 14th ed.,edited by Anthony S. Fauci, et al. New York: McGraw-Hill, 1998, 2419-2434.
Schwartz, Seymour, Shires, Tom and Spencer, Frank
C.Principles of Surgery, 7th ed. New York, McGraw Hill, 1998.
Stern, Robert C. “Pulmonary abscess.” In Nelson Textbook of Pediatrics, 16th ed., edited by Richard E. Behrman et al., Philadelphia, Saunders, 2000, 1309-1310.
Townsend, Courtney M. Sabiston Textbook of Surgery: The Biological Basis of Modern Surgical Practice, 16th ed. Philadelphia, Saunders, 2001.
PERIODICALS
Balatsouras DG, Kloutsos GM, Protopapas D, Korres S, Economou C. “Submasseteric abscess.” Journal of Laryngology and Otology115, no. 1 (2001): 68-70. Chua, F. “Clinical picture: paravertebral abscess.” Lancet357,
no. 9251 (2001): 168-70.
Rockwell PG. “Acute and chronic paronychia.” American Family Physician63, no. 6 (2001): 1113-6.
Struk DW, Munk PL, Lee MJ, Ho SG, Worsley DF. “Imaging of soft tissue infections.” Radiology Clinics of North America39, no. 2 (2001): 277-303.
Taiwo B. “Psoas abscess: a primer for the internist.” Southern Medical Journal94, no. 1 (2001): 2-5.
ORGANIZATIONS
American Academy of Family Physicians, 11400 Tomahawk Creek Parkway, Leawood, KS 66211-2672. (913) 906-6000. <http://www.aafp.org/>. fp@aafp.org.
American Society of Clinical Pathologists, 2100 West Harrison Street, Chicago IL 60612. (312) 738-1336. <http://www.ascp.org/index.asp>. info@ascp.org. College of American Pathologists, 325 Waukegan Road,
Northfield, IL 60093. (800) 323-4040. <http://www.cap.org/>.
OTHER
American Society of Colon and Rectal Surgeons. <http://www.fascrs.org/brochures/anal-abscess.html>. Merck Manual. <http://www.merck.com/pubs/mmanual/
section3/chapter35/35d.htm>.
South Bank University. <http://www.sbu.ac.uk/~dirt/ museum/p6-216.html>.
Tuberculosis.Net. <http://www.tuberculosis.net/imagesof/ rulcavity.htm>.
University of Bristol. <http://www.brisbio.ac.uk/ROADS/ subject-listing/abcess.html>.
University of California-San Diego:
<http://burn.ucsd.edu/remedies/abcess.html>. University of Kansas Medical Center.
<http://www.kumc.edu/instruction/medicine/pathology/ed /ch_28/c28_s24.html>.
L. Fleming Fallon, Jr., MD, DrPH
Achromatopsia
see
Color blindness
Acid-base balance
DefinitionAcid-base balance can be defined as homeostasis of the body fluids at a normal arterial blood pH ranging between 7.37 and 7.43.
Description
An acid is a substance that acts as a proton donor. In contrast, a base, also known as an alkali, is frequently defined as a substance that combines with a proton to form a chemical bond. Acid solutions have a sour taste and produce a burning sensation with skin contact. A base is any chemical compound that produces hydroxide ions when dissolved in water. Base solutions have a bitter taste and a slippery feel. Despite variations in metabo-lism, diet, and environmental factors, the body’s acid-base balance, fluid volume, and electrolyte concentration are maintained within a narrow range.
Function
Many naturally occurring acids are necessary for life. For example, hydrochloric acid is secreted by the stomachto assist with digestion. The chemical composi-tion of food in the diet can have an effect on the body’s acid-base production. Components that affect acid-base balance include protein, chloride, phosphorus, sodium, potassium, calcium, and magnesium. In addition, the rate at which nutrients are absorbed in the intestine will alter acid-base balance.
Cells and body fluids contain acid-base buffers, which help prevent rapid changes in body fluid pH over short periods of time, until the kidneyspulmonary sys-tems can make appropriate adjustments. The kidneys and pulmonary system then work to maintain acid-base bal-ance through excretion in the urine or respiration. The partial pressure of carbon dioxide gas (PCO2) in the pul-monary system can be measured with a blood sample and
correlates with blood carbon dioxide (CO2) levels. PCO2 can then be used as an indicator of the concentration of acid in the body. The concentration of base in the body can be determined by measuring plasma bicarbonate (HCO3-) concentration. When the acid-base balance is disturbed, the respiratory systemcan alter PCO2 quick-ly, thus changing the blood pH and correcting imbal-ances. Excess acid or base is then excreted in the urine by the renal system to control plasma bicarbonate concen-tration. Changes in respiration occur primarily in minutes to hours, while renal function works to alter blood pH within several days.
Role in human health
Production of CO2is a result of normal body metab-olism. Exercise or serious infections will increase the production of CO2through increased respiration in the lungs. When oxygen (O2) is inhaled and CO2is exhaled, the blood transports these gases to the lungs and body tis-sues. The body’s metabolism produces acids that are buffered and then excreted by the lungs and kidneys to maintain body fluids at a neutral pH. Disruptions in CO2 levels and HCO3- create acid-base imbalances. When acid-base imbalances occur, the disturbances can be broadly divided into either acidosis (excess acid) or alka-losis (excess base/alkali).
Common diseases and disorders
Acid-base metabolism imbalances are often charac-terized in terms of the HCO3-/CO2buffer system. Acid-base imbalances result primarily from metabolic or res-piratory failures. An increase in HCO3- is called meta-bolic alkalosis, while a decrease in the same substance is called metabolic acidosis. An increase in PCO2, on the other hand, is known as respiratory acidosis, and a decrease in the same substance is called respiratory alka-losis.
Acidosis
Acidosis is a condition resulting from higher than normal acid levels in the body fluids. It is not a disease, but may be an indicator of disease. Metabolic acidosis is related to processes that transform food into energy and body tissues. Conditions such as diabetes, kidney failure, severe diarrhea, and poisoningcan result in metabolic acidosis. Mild acidosis is often compensated by the body in a number of ways. However, prolonged acidosis can result in heavy or rapid breathing, weakness, and headache. Acidemia (arterial pH < 7.35) is an accumula-tion of acids in the bloodstream that may occur with severe acidosis when the acid load exceeds respiratory capacity. This condition can sometimes result in coma
and, if the pH falls below 6.80, it will lead to death. Diabetic ketoacidosis is a condition where excessive glucagon and a lack of insulin contribute to the produc-tion of ketoacids in the liver. This condiproduc-tion can be caused by chronic alcoholism and poor carbohydrate utilization.
Respiratory acidosis is caused by the lungs’s failure to remove excess carbon dioxide from the body, reducing
Acid-base balance
K E Y T E R M S
Acid—(a) Any ionic or molecular substance that can act as a proton donor; (b) A sour-tasting sub-stance, like vinegar; (c) A chemical compound that can react with a base to form a salt.
Acidosis—A dangerous condition where the blood and body tissues are less alkaline (or more acidic) than normal.
Alkalosis—Excessive alkalinity of the blood and body tissue.
Alkalemia—Abnormal blood alkalinity.
Base—(a) Any ionic or molecular substance that can act as a proton acceptor; (b) A bitter-tasting substance which has a soapy feel; (c) A chemical compound that can react with an acid to form a salt. A base can also be called an alkali.
Bicarbonate—A salt of carbonic acid produced by neutralizing a hydrogen ion.
Diabetic ketoacidosis—A condition characterized by excessive thirst and urination. Other symptoms may include appetite loss, nausea, vomiting, and rapid deep breathing.
Diuretic—An agent or drug that eliminates exces-sive water in the body by increasing the flow of urine.
Electrolyte—A substance such as an acid, bases, or salt. An electrolyte’s water solution will con-duct an electric current and ionizes. Acids, bases, and salts are electrolytes.
Homeostasis—An organism’s regulation of body processes to maintain internal equilibrium in tem-perature and fluid content.
Hypochloremic alkalosis—A large loss of chloride.
G A L E E N C Y C L O P E D I A O F N U R S I N G A N D A L L I E D H E A LT H 1 0
the pH in the body. Several conditions, including chest injury, blockage of the upper air passages, and severe lung disease, may lead to respiratory acidosis. Blockage of the air passages may be caused by bronchitis, asthma, or airway obstruction, resulting in mild or severe acido-sis. Regular, consistent retention of carbon dioxide in the lungs is referred to as chronic respiratory acidosis. This disorder results in only mild acidosis because it is bal-anced by increased bicarbonate production.
The predominant symptoms of acidosis are some-times difficult to distinguish from symptoms of an under-lying disease or disorder. Mild conditions of acidosis may be asymptomatic or may be accompanied by weakness or listlessness, nausea, and vomiting. Most often, severe metabolic acidosis (pH < 7.20) is associated with increased respiration to compensate for a shortage of HCO3-. This is followed by a secondary decrease in PCO2 that occurs as part of respiratory compensation process. Treatment options for acidosis typically require correc-tion of the underlying condicorrec-tion by venous administracorrec-tion of sodium bicarbonate or another alkaline substance.
Alkalosis
Alkalosis is a condition resulting from a higher than normal level of base/alkali in the body fluids. An exces-sive loss of HCO3- in the blood causes metabolic alkalo-sis. The body can compensate for mild alkalinity, but prolonged alkalosis can result in convulsions, muscular weakness, and even death if the pH rises above 7.80. Alkalosis can be caused by drugs or disorders that upset the normal acid-base balance. Prolonged vomiting and hyperventilation (abnormally fast, deep breathing) can result in alkalosis.
The predominant symptoms of alkalosis are neuro-muscular hyperexcitability and irritability. Alkalemia (abnormal blood alkalinity) increases protein binding of ionized calcium even though plasma total calcium does not change. Severe cases may induce hypocalcemia (a
low level of plasma calcium). Low plasma potassium leads to a condition called hypokalemic alkalosis. It is frequently accompanied by metabolic alkalosis, resulting in cramping, muscle weakness, polyuria, and ileus (obstruction of the intestines). Diuretic medications may cause hypokalemic alkalosis. Prolonged vomiting may induce hypochloremic alkalosis (a large loss of chloride). The kidneys may conserve bicarbonate in order to com-pensate for the chloride reduction. Comcom-pensated alkalo-sis results when the body has partially compensated for alkalosis, and has restored normal acid-base balances. However, in compensated alkalosis, abnormal bicarbon-ate and carbon dioxide levels persist.
Alkalosis requires correction of the underlying con-dition and may involve venous administration of a weak acid to restore normal balance. If the source of alkalosis is excessive drug intake, it may be appropriate to reduce intake to restore the normal acid-base balance.
Respiratory alkalosis results from decreased CO2 levels caused by conditions such as hyperventilation (a faster breathing rate), anxiety, and fever. The pH is ele-vated in the body. Hyperventilation causes the body to lose excess carbon dioxide in expired air and can be trig-gered by altitude or a disease that reduces the amount of oxygen in the blood. Symptoms of respiratory alkalosis may include dizziness, lightheadedness, and numbing of the hands and feet. Treatments include breathing into a paper bag or a mask that induces rebreathing of carbon dioxide.
Resources BOOKS
Shaw, Patricia, ed. Fluids & Electrolytes Made Incredibly Easy!Springhouse, PA: Springhouse Publishing Co., 1997.
PERIODICALS
Remer, T. “Influence of diet on acid-base balance.” Seminars in Dialysis13, no. 4 (2000): 221–226.
Acid-base balance
Respiratory acidosis Respiratory depression (drugs, central nervous system
trauma)
Pulmonary disease (pneumonia, chronic obstructive pul-monary disease, respiratory underventilation)
Kidneys will retain increased amounts of HCO3–to increase pH
Acid-base disturbances, causes, and compensatory mechanisms
Acid-base disturbance Common cause Mode of compensation
Respiratory alkalosis Hyperventilation (emotions, pain, respirator
overventilation)
Kidneys will excrete increased amounts of HCO3–to lower pH
Metabolic acidosis Diabetes, shock, renal failure, intestinal fistula Lungs “blow off” CO2to raise pH
Metabolic alkalosis Sodium bicarbonate overdose, prolonged vomiting,
nasogastric drainage
Lungs retain CO2to lower pH
OTHER
Bookallil, Michael. “pH of the blood: acid-base balance.” <http://www.usyd.edu.au/su/anaes/lectures/acidbase_mjb/ frameversion.html>.
Grogono, Alan. “Acid-base tutorial.” <http://www.acid-base.com>.
Crystal Heather Kaczkowski, MSc.
Acid-fast culture
DefinitionThe term acid-fast refers to a type of organism not readily decolorized by acid after staining. An acid-fast culture is the microbiological analysis of such an organ-ism. An acid-fast culture refers to the process of detec-tion, growth, isoladetec-tion, identificadetec-tion, and antibiotic sus-ceptibility testing of mycobacteria that cause pulmonary tuberculosisand other infections such as skin, abdomi-nal, and disseminated (widely spread throughout many organs).
Purpose
The acid-fast culture is used to isolate Mycobacteri-um tuberculosis when tuberculosis (TB) is suspected. More recently the test has become important for the iden-tification of other acid-fast organisms including
Mycobacterium aviumcomplex (MAC), Mycobacterium bovis, and Mycobacterium africanum responsible for causing tuberculosis in AIDSpatients and other immuno-suppressed persons. Antibiotic sensitivity testing per-formed when cultures are positive or when patients are known to have tuberculosis determines the appropriate drugs for treatment. This is essential because of the emergence of tuberculosis strains that are resistant to many of the antibioticsthat were once effective in treat-ing this disease. The test is also used to differentiate tuberculosis from carcinoma and bronchiectasis that may appear similar on x ray.
Precautions
Antibiotics and some sulfonamides may interfere with test results, causing the results to be falsely nega-tive. Sufficient organisms may not be recovered to diag-nose infectionwhen a single culture sample is collected. Therefore, sputum cultures should be collected on three consecutive mornings.
Special safety precautions
Health care workers involved with collection and handling of specimens from patients suspected of having tuberculosis or other mycobacterial infections should observe universal precautions for the prevention of transmission of bloodborne pathogens. In addition, health care personnel working with patients and handling specimens from patients suspected of having tuberculosis must be given a skin test (e.g. Mantoux or PPD test) on a regular basis. Precautions must be followed closely when handling mycobacterial specimens. The laboratory per-sonnel who process and handle the infectious material from the patient are at greatest risk (about three times higher than other laboratory personnel) for tuberculosis infection or skin test positivity. The hazard of working in a laboratory that handles mycobacterial specimens is greatly reduced if the personnel follow proper procedures when handling and processing the specimens. All pro-cessing should take place in a biologic safety cabinet (BSC). The biologic safety cabinets used in the clinical mycobacterial laboratory are of two types: Class I, or negative-pressure cabinets, and Class II, or vertical-lam-inar-flow cabinets. Correct operation of these safety devices along with proper maintenance and testing of the air flow are essential to their performance. Yearly inspec-tion of the cabinets by trained individuals is required.
Processing specimens, testing organisms, and trans-ferring viable cultures must be carried out within the BSC. After processing specimens or working under the BSC, the area inside the cabinet is disinfected and a UV (ultraviolet) light located within the cabinet is turned on to kill any organisms on the surface of the work area as well as any airborne bacteria. After performing a proce-dure, the work area must be decontaminated with a dis-infectant solution (e.g., the use of a phenol-soap mixture containing orthophenol or phenolic derivitives with an effective contact time of 10-30 minutes).
Protective clothing including gloves, fluid-proof gowns, goggles, and face mask or respirator is recom-mended for laboratory personnel working in the mycobac-terial laboratory. Incinerators (no bunsen burners) are used within the BSC to reduce aerosoling of bacteria from infectious material while processing and culturing.
Description
Tuberculosis is an infection caused by Mycobac-terium tuberculosis, a disease which is a major health problem worldwide. Mycobacterium tuberculosis is a rod-shaped bacterium characterized by acid-fastness. It is commonly transmitted via the air to the lungs, where it thrives, causing fever, cough, and hemoptysis (coughing up blood-tainted secretions). Tuberculosis is highly
