(BQ) Part 1 book Egan''s fundamentals of respiratory care has contents: History of respiratory care, delivering evidence based respiratory care, principles of infection prevention and control, pulmonary function testing,... and other contents.
Fundamentals oF Respiratory Care I I KACMAREK STOLLER HEUER ROBERT M JA'M ES K V ALBERT J FR E WITH TEXTBOOK PURCHASE EVOLVE.ELSEVIER.COM ABBREVIATIONS Δ µ µg µm µV A a AARC ABG(s) A/C ACBT ADH AIDS AII ALI ALV ANP AOP APRV ARDS ARF ASV ATC ATM ATPD ATPS auto-PEEP AV AVP B BAC BE bilevel PAP BiPAP BP BPD BSA BTPS BUN C c C′ °C CaO2 C( a − v )O2 CC cc Cc′O2 CD CDC CDH CHF CI CINAHL CL cm cm H2O CMS CMV CNS CO change in micromicrogram micrometer microvolt alveolar arterial American Association for Respiratory Care arterial blood gas(es) assist/control active cycle of breathing technique antidiuretic hormone acquired immunodeficiency syndrome airborne infection isolation acute lung injury adaptive lung ventilation atrial natriuretic peptide apnea of prematurity airway pressure release ventilation acute respiratory distress syndrome acute respiratory failure adaptive support ventilation automatic tube compensation atmospheric pressure ambient temperature and pressure, dry ambient temperature and pressure, saturated with water vapor unintended positive end expiratory pressure arteriovenous arginine vasopressin barometric blood alcohol content base excess bilevel positive airway pressure registered trade name for bilevel PAP device blood pressure bronchopulmonary dysplasia body surface area body temperature and pressure, saturated with water vapor blood urea nitrogen compliance capillary pulmonary-end capillary degrees of Celsius arterial content of oxygen arterial-to-mixed venous oxygen content difference closing capacity cubic centimeter content of oxygen of the ideal alveolar capillary dynamic characteristic or dynamic compliance U.S Centers for Disease Control and Prevention congenital diaphragmatic hernia congestive heart failure cardiac index Cumulative Index to Nursing and Allied Health Literature lung compliance (also CLung) centimeters centimeters of water pressure Centers for Medicare and Medicaid Services controlled (continuous) mandatory or mechanical ventilation central nervous system carbon monoxide CO2 COHb COLD COPD CPAP CPG CPOE CPP CPPB CPPV CPR CPT CPU CQI CRCE Cs CSF CSV CT CT CV CvO2 CvO2 CVP D d DC DC-CMV DC-CSV DIC Dm DO2 DPAP DPPC DVT E EAdi ECCO2R ECG ECLS ECMO EDV EE EEP EHR EIB EMR EPAP ERV ET ETCO2 or etCO2 F °F f FDA FEF FEFmax FEFX FETX FEV1 carbon dioxide carboxyhemoglobin chronic obstructive lung disease chronic obstructive pulmonary disease continuous positive airway pressure Clinical Practice Guideline computerized physician order entry cerebral perfusion pressure continuous positive pressure breathing continuous positive pressure ventilation cardiopulmonary resuscitation chest physical therapy central processing unit continuous quality improvement continuing respiratory care education static compliance cerebrospinal fluid continuous spontaneous ventilation computed tomography tubing compliance (also Ctubing) closing volume venous oxygen content mixed venous oxygen content central venous pressure diffusing capacity diameter discharges, discontinue dual controlled–continuous mandatory ventilation dual controlled–continuous spontaneous ventilation disseminated intravascular coagulation diffusing capacity of the alveolocapillary membrane oxygen delivery demand positive airway pressure dipalmitoyl phosphatidylcholine deep venous thrombosis elastance electrical activity of the diaphragm extracorporeal carbon dioxide removal electrocardiogram extracorporeal life support extracorporeal membrane oxygenation end-diastolic volume energy expenditure end expiratory pressure electronic health record exercise-induced bronchospasm electronic medical record end positive airway pressure expiratory reserve volume endotracheal tube end-tidal CO2 fractional concentration of a gas degrees Fahrenheit respiratory frequency, respiratory rate U.S Food and Drug Administration forced expiratory flow maximal forced expiratory flow achieved during FVC forced expiratory flow, related to some portion of FVC curve forced expiratory time for a specified portion of FVC forced expiratory volume at second FiCO2 FIF FiO2 FIVC FRC FVC FVS f/VT Gaw g/dl [H+] HAP Hb HBO HCAP HCH HCO3− H2CO3 He He/O2 HFFI HFJV HFNC HFO HFOV HFPV HFPPV HFV HHb HMD HME HMEF H2O HR ht Hz IBW I IC ICP ICU ID I:E ILD IMPRV IMV INO IPAP IPPB IPPV IR IRB IRDS IRV IRV IV IVC IVH IVOX kcal kg kg-m kPa KPI L LAP fractional inspired carbon dioxide forced inspiratory flow fractional inspired oxygen forced inspiratory vital capacity functional residual capacity forced vital capacity full ventilatory support rapid shallow breathing index (frequency divided by tidal volume) airway conductance grams per deciliter hydrogen ion concentration hospital-acquired pneumonia hemoglobin hyperbaric oxygen (therapy) health care–associated pneumonia hygroscopic condenser humidifier bicarbonate carbonic acid helium helium/oxygen mixture; heliox high-frequency flow interrupter high-frequency jet ventilation high-flow nasal cannula high-frequency oscillation high-frequency oscillatory ventilation high-frequency percussive ventilation high-frequency positive pressure ventilation high-frequency ventilation reduced or deoxygenated hemoglobin hyaline membrane disease heat and moisture exchanger heat and moisture exchange filter water heart rate height hertz ideal body weight inspired inspiratory capacity intracranial pressure intensive care unit inner diameter inspiratory-to-expiratory ratio interstitial lung disease intermittent mandatory pressure release ventilation intermittent mandatory ventilation inhaled nitric oxide inspiratory positive airway pressure intermittent positive pressure breathing intermittent positive pressure ventilation infrared institutional review board infant respiratory distress syndrome inverse ratio ventilation inspiratory reserve volume intravenous inspiratory vital capacity intraventricular hemorrhage intravascular oxygenator kilocalorie kilogram kilogram-meters kilopascal key performance indicator liter left atrial pressure lb LBW LED LFPPV-ECCO2R LMS LTACH LV LVEDP LVEDV LVSW m2 MABP MAlvP MAP MAS max MDI MDR mEq/L MEP metHb mg mg% mg/dl MI MICP MI-E MIF MIGET MIP ml mm MMAD mm Hg mmol MMV mo MOV mPaw − Paw MRI msec MV MVV NaBr NaCl NAVA NBRC NEEP nHFOV NICU NIF NIH NIV nM nm NMBA nM/L NO NO2 NP NPO NPV NPPV NSAIDs nSIMV pound low birth weight light emitting diode low-frequency positive pressure ventilation with extracorporeal carbon dioxide removal learning management system long term acute care hospital left ventricle left ventricular end-diastolic pressure left ventricular end-diastolic volume left ventricular stroke work meters squared mean arterial blood pressure mean alveolar pressure mean arterial pressure or mean airway pressure meconium aspiration syndrome maximal metered dose inhaler multidrug resistant milliequivalents per liter maximum expiratory pressure methemoglobin milligram milligram percent milligrams per deciliter myocardial infarction mobile intensive care paramedic mechanical insufflation-exsufflation maximum inspiratory force multiple inert gas elimination technique minute maximum inspiratory pressure milliliter millimeter median mass aerodynamic diameter millimeters of mercury millimole mandatory minute ventilation month minimal occluding volume mean airway pressure magnetic resonance imaging millisecond mechanical ventilation maximum voluntary ventilation sodium bromide sodium chloride neurally adjusted ventilatory assist National Board of Respiratory Care negative end expiratory pressure nasal high-frequency oscillatory ventilation neonatal intensive care unit negative inspiratory force (also see MIP and MIF) National Institutes of Health noninvasive ventilation nanomole nanometer neuromuscular blocking agent nanomole per liter nitric oxide nitrous oxide nasopharyngeal nothing by mouth negative pressure ventilation noninvasive positive pressure ventilation nonsteroidal antiinflammatory drugs nasal synchronized intermittent mandatory ventilation EGAN’S Fundamentals OF Respiratory Care YOU’VE JUST PURCHASED MORE THAN A TEXTBOOK! 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Go to evolve.elsevier.com/html/shop-promo.html to search and browse for products EGAN’S Fundamentals OF Respiratory Care Robert M Kacmarek, PhD, RRT EDITION Professor of Anesthesiology Department of Anesthesia, Critical Care and Pain Medicine Harvard Medical School; Director of Respiratory Care Respiratory Care Services Massachusetts General Hospital Boston, Massachusetts James K Stoller, MD, MS, FAARC, FCCP Jean Wall Bennett Professor of Medicine Cleveland Clinic Lerner College of Medicine; Chair, Education Institute Cleveland Clinic Cleveland, Ohio Albert J Heuer, PhD, MBA, RRT, RPFT Program Director and Professor Masters of Science in Health Care Management & Respiratory Care Program Rutgers, School of Health Related Professions Newark, New Jersey Consulting Editors Robert L Chatburn, Richard H Kallet, MHHS, RRT-NPS, FAARC Adjunct Professor Department of Medicine Cleveland Clinic Lerner College of Medicine; Clinical Research Manager Department of Respiratory Therapy Cleveland Clinic Cleveland, Ohio MS, RRT Director of Quality Assurance Respiratory Care Division Department of Anesthesia University of California, San Francisco; San Francisco General Hospital San Francisco, California 11 3251 Riverport Lane St Louis, Missouri 63043 EGAN’S FUNDAMENTALS OF RESPIRATORY CARE, ELEVENTH EDITION ISBN: 978-0-323-34136-3 Copyright © 2017 by Elsevier, Inc All rights reserved No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher Details on how to seek permission, further information about the Publisher’s permissions policies and our arrangements with organizations such as the Copyright Clearance Center and the Copyright Licensing Agency, can be found at our website: www.elsevier.com/permissions This book and the individual contributions contained in it are protected under copyright by the Publisher (other than as may be noted herein) Notices Knowledge and best practice in this field are constantly changing As new research and experience broaden our understanding, changes in research methods, professional practices, or medical treatment may become necessary Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds, or experiments described herein In using such information or methods they should be mindful of their own safety and the safety of others, including parties for whom they have a professional responsibility With respect to any drug or pharmaceutical products identified, readers are advised to check the most current information provided (i) on procedures featured or (ii) by the manufacturer of each product to be administered, to verify the recommended dose or formula, the method and duration of administration, and contraindications It is the responsibility of practitioners, relying on their own experience and knowledge of their patients, to make diagnoses, to determine dosages and the best treatment for each individual patient, and to take all appropriate safety precautions To the fullest extent of the law, neither the Publisher nor the authors, contributors, or editors, assume any liability for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in the material herein Previous editions copyrighted 2013, 2009, 2003, 1999, 1995, 1990, 1982, 1977, 1973, and 1969 Library of Congress Cataloging-in-Publication Data Egan’s fundamentals of respiratory care / [edited by] Robert M Kacmarek, James K Stoller, Albert J Heuer ; consulting editors, Robert L Chatburn, Richard H Kallet.—Eleventh edition p ; cm Fundamentals of respiratory care Includes bibliographical references and index ISBN 978-0-323-34136-3 (hardcover : alk paper) I. Kacmarek, Robert M., editor. II. Stoller, James K., editor. III. Heuer, Albert J., editor. IV. Chatburn, Robert L., editor. V. Kallet, Richard H., editor. VI. Title: Fundamentals of respiratory care [DNLM: 1. Respiratory Therapy–methods. 2. Respiratory Tract Diseases–therapy. WF 145] RM161 615.8′36–dc23 2015036692 Content Strategist: Sonya Seigafuse Content Development Manager: Billie Sharp Content Development Specialist: Heather Yocum Publishing Services Manager: Catherine Jackson Senior Project Manager: Rachel E McMullen Design Direction: Renee Duenow Printed in Canada Last digit is the print number: 9 8 7 6 5 4 3 2 For Robert, Julia, Katie, and Callie, who all make it worthwhile, and for Cristina who has made me whole again RMK I dedicate this work to the memory of my parents, Norma and Alfred Stoller, who instilled the values of rigor and commitment that inform this book; to my wife, Terry Stoller, whose love and support have been the foundation upon which my contribution to this book is possible; to our son, Jake Fox Stoller, whose shining promise gives purpose and illuminates the world; and to generations of Respiratory Therapists, whose daily activities and commitment better our health and give hope JKS To my mother, who is long gone from this earth, but continues to be the most dominant, positive influence in my life Mom taught me many lessons, including that failure is to be expected on the way to success, and excellence can only be achieved through hard work, sacrifice, and perseverance These lessons have proven invaluable and, hence, my work on this text is dedicated to my mother, Edith; as well as my wife, Laurel; my faculty and students; fellow respiratory therapists; and the patients we tirelessly serve AJH Contributors Loutfi S Aboussouan, MD Thomas A Barnes, EdD, RRT, FAARC Staff Respiratory Institute Cleveland Clinic Cleveland, Ohio Professor Emeritus of Cardiopulmonary Sciences Master of Science in Respiratory Care Leadership Program Northeastern University Boston, Massachusetts Neila Altobelli, BA, RRT Will Beachey, PhD, RRT, FAARC Respiratory Therapist, Clinical Scholar, Clinical Educator Department of Respiratory Care Massachusetts General Hospital Boston, Massachusetts Professor and Chair Department of Respiratory Therapy University of Mary/CHI St Alexius Health Bismarck, North Dakota Arzu Ari, PhD, RRT, PT, CPFT, FAARC Jason Bordelon, MHA, RRT Associate Professor Department of Respiratory Therapy Georgia State University Atlanta, Georgia Director Department of Respiratory & Clinical Diagnostics Cleveland Clinic Abu Dhabi Abu Dhabi, United Arab Emirates Rendell W Ashton, MD Jeffrey T Chapman, MD Pulmonary and Critical Care Fellowship Program Director Department of Critical Care Medicine Cleveland Clinic Cleveland, Ohio Chief Respiratory & Critical Care Institute Cleveland Clinic Abu Dhabi Abu Dhabi, United Arab Emirates Joseph T Azok, MD Robert L Chatburn, MHHS, RRT-NPS, FAARC Staff Radiologist Section of Thoracic Imaging, Imaging Institute Cleveland Clinic Cleveland, Ohio Adjunct Professor Department of Medicine Cleveland Clinic Lerner College of Medicine; Clinical Research Manager Department of Respiratory Therapy Cleveland Clinic Cleveland, Ohio Jami E Baltz, RD, CNSC Clinical Dietitian Department of Clinical Nutrition Stanford Health Care Stanford, California Lorenzo Berra, MD Assistant Professor of Anesthesia Department of Anesthesia Harvard Medical School; Anesthesiologist and Intensivist Department of Anesthesia, Critical Care and Pain Medicine Massachusetts General Hospital Boston, Massachusetts vi Daniel W Chipman, BS, RRT Assistant Director Respiratory Care Massachusetts General Hospital Boston, Massachusetts Zaza Cohen, MD, FCCP Medical Director, Respiratory Care Program—North Rutgers School of Health Related Professions Newark, New Jersey; Director, Intensive Care Unit Hackensack University Medical Center—Mountainside Montclair, New Jersey Contributors Douglas D Deming, MD Daniel F Fisher, MS, RRT Professor and Chief Division of Neonatology Department of Pediatrics Loma Linda University School of Medicine Loma Linda, California Assistant Director Respiratory Care Services Massachusetts General Hospital Boston, Massachusetts Anthony L DeWitt, RRT, CRT, BHA, JD Partner Bartimus, Frickleton, Robertson & Goza, PC Jefferson City, Missouri Faculty Instructor Respiratory Care Program Rutgers School of Health Related Professions Newark, New Jersey Enrique Diaz-Guzman, MD Thomas G Fraser, MD Associate Professor of Medicine Division of Pulmonary, Critical Care and Sleep Medicine University of Alabama at Birmingham Birmingham, Alabama Vice Chairman Department of Infectious Disease Cleveland Clinic Cleveland, Ohio Patrick J Dunne, MEd, RRT, FAARC Douglas S Gardenhire, EdD, RRT-NPS, FAARC President/CEP HealthCare Productions, Inc Fullerton, California Chair and Clinical Associate Professor Department of Respiratory Therapy Georgia State University Atlanta, Georgia Raed A Dweik, MD, FACP, FRCP(C), FCCP, FCCM, FAHA Professor of Medicine Cleveland Clinic Lerner College of Medicine; Director, Pulmonary Vascular Program Departments of Pulmonary and Critical Care Medicine/ Respiratory Institute Cleveland Clinic Cleveland, Ohio Patricia English, MS, RRT ECMO Program Coordinator Department of Respiratory Care Massachusetts General Hospital Boston, Massachusetts Matthew C Exline, MD, MPH Assistant Professor; Medical Director, Medical Intensive Care Unit Division of Pulmonary, Allergy, Critical Care, and Sleep Medicine The Ohio State University Columbus, Ohio James B Fink, RRT, NPS, PhD, FAARC, FCCP Adjunct Professor Division of Respiratory Therapy Georgia State University Atlanta, Georgia vii Crystal L Fishman, BS, RRT Donna D Gardner, Dr(c)PH, RRT, FAARC Chair, Department of Respiratory Care Interim Chair, Department of Clinical Laboratory Sciences University of Texas Health Science Center at San Antonio San Antonio, Texas Michael A Gentile, RRT, FAARC, FCCM Associate in Research Department of Critical Care Medicine Duke University Medical Center Durham, North Carolina Umur Hatipoğlu, MD Quality Improvement Officer Respiratory Institute Cleveland Clinic Cleveland, Ohio Albert J Heuer, PhD, MBA, RRT, RPFT Program Director and Professor Masters of Science in Health Care Management & Respiratory Care Program Rutgers, School of Health Related Professions Newark, New Jersey 478 SECTION III • Assessment of Respiratory Disorders based on gender and height, with reference values of approximately 18 mg/kg body weight per day for women and approximately 23 mg/kg body weight per day for men.7 Factors that influence creatinine excretion and complicate its interpretation include age, diet, exercise, stress, trauma, fever, and sepsis.17 Nitrogen Balance (Protein Catabolism) Approximately 16% of protein is nitrogen, and nitrogen is a major by-product of protein catabolism Therefore measuring nitrogen balance is an important aspect of nutritional assessment The urinary excretion rate of nitrogen is used to assess protein adequacy Nitrogen balance is calculated as follows: TABLE 23-2 Physical Signs of Malnutrition Normal Abnormal Demeanor Alert, responsive Positive outlook Reasonable for build Lethargic Negative attitude Underweight Overweight, obese Dull, sparse; easily, painlessly plucked Pale conjunctiva Redness, dryness Chapped, red, swollen Bright red, purple Swollen or shrunken Several longitudinal furrows Caries, painful, mottled, or missing Spongy, bleeding, receding Rashes, swelling Light or dark spots Dry, cracked Spoon-shaped or ridged Spongy bases Muscle wasting Skeletal deformities Loss of balance Weight Hair Eyes Glossy, full, firmly rooted Uniform color Bright, clear, shiny Lips Tongue Smooth Deep red Slightly rough One longitudinal furrow Teeth Bright, painless Gums Pink, firm The dietary protein conversion factor is 6.25 g of nitrogen per 1 g of protein The amount of nitrogen excretion in the urine is typically measured as the 24-hour urinary urea nitrogen Between 3 g/day and 5 g/day is added to the 24-hour urinary urea nitrogen to estimate the average daily unmeasured nitrogen lost through other sources (skin and gastrointestinal [GI] sloughing, hair loss, sweat, feces) Theoretically, increasing exogenous protein, reduces endogenous protein loss However, the accuracy of 24-hour urine collection is limited by alterations in renal or liver function, large insensible losses (burns, high-output fistulas, wounds, or ostomies), and inflammatory conditions.20 Skin Clear, smooth, firm, slightly moist Nails Pink, firm Mobility Erect posture Good muscle tone Walks without pain or difficulty Immune Status Impaired immunity (anergy) is common in malnutrition, especially the kwashiorkor type Two laboratory values, white blood cell count and percentage of lymphocytes, are indices of compromised immunity The result is often a reduction in the total lymphocyte count Many nonnutrition variables, including disease states and drugs, influence these laboratory values, so their usefulness in assessing nutrition status is questioned.21 mouth and gums, skin and nails), so incorporating the appearance of these features into the physical examination can alert the clinician to signs of nutrient deficiencies (see Table 23-2 for physical signs of nutrition status) In addition to malnutrition, other causes of these abnormalities include medical therapies, anemia, allergies, sunburn, medications, poor hygiene practices, aging, or various pathologic processes.24 Patients with persistent malnutrition often appear very thin When the bony structures of the chest are conspicuously visible, a patient is said to be cachexic Special attention should be given to fluid retention because this can mask weight loss.25 Other physical findings such as skeletal muscle depletion can be clinical indicators of inflammation or signs of systemic inflammatory response Nitrogen balance = Nitrogen intake − Nitrogen losses Protein intake Nitrogen intake = 6.25 Nitrogen losses = UUN excretion in grams + 3-5 g (for insensible losses) Pulmonary Function Pulmonary function test results may change with malnutrition Respiratory muscle weakness reduces both maximal inspiratory and expiratory pressures and reduced vital capacity These limitations in turn reduce the ability to maintain sufficient lung volumes to prevent atelectasis and produce an effective cough to clear secretions Diminished strength and endurance of respiratory muscles increases the susceptibility to respiratory muscle fatigue and the inability to maintain effective spontaneous breathing The negative effects of malnutrition on both respiratory muscle function and immunologic function increase the risk for respiratory infections and pneumonia.22 Nutrition-Focused Physical Findings The physical signs of malnutrition often appear first in specific tissues where high cell turnover occurs23 (e.g., hair, eyes, lips, From Lutz C, Przytulski K: Nutrition and diet therapy, ed 5, Jackson Community College; Jackson, MS, 2011, FA Davis OUTCOMES OF NUTRITION ASSESSMENT With nutrition intervention, patients improve their nutrient intake and reduce mortality and morbidity Improved nutrition status increases the patient’s tolerance of therapeutic regimens in the treatment of disease and decreases recovery time The resulting economic benefits are multifaceted and include shorter and less frequent hospital stays, reduced need for medication or medical care or extended care, and increased years of productivity.26 Nutrition Assessment • CHAPTER 23 MACRONUTRIENTS AND ENERGY REQUIREMENTS The nutrition assessment determines a nutrition care plan for the patient Calorie or energy needs are fundamental to these recommendations Several means are available to determine calorie needs These include calculating total calories using a mathematical formula or predictive equation Macronutrients supply the energy requirements of the body The three macronutrients are protein, carbohydrate, and fat Each contributes to calorie intake with 4, 4, and calories (kcal) per gram Alcohol is the only other calorie source, with approximately 7 kcal/g Box 23-2 outlines the factors influencing energy and macronutrient needs Estimating Energy Requirements An individual’s energy requirement represents the ratio of energy intake to energy expenditure relative to body weight, activity level, and stressors The classic measure of energy expenditure is the basal metabolic rate (BMR) Obtained after 10 hours of fasting, the BMR measures the number of calories (kcal) expended at rest per square meter of body surface per hour (kcal/m2/hr) BMR varies by body size, age, and sex Caloric needs for energy expenditure increase beyond the BMR based on activity level, stage of growth (pregnancy, lactation), and extent of injury In clinical practice, interest is focused on a patient’s daily energy requirements (kilocalories per day) Multiple methods are available for estimating daily energy needs The “quick method,” based on a 1997 equation provided by the American College of Chest Physicians, estimates daily energy needs based on a simple body weight factor of 20 to 35 kcal/kg.27 Alter natively, predictive equations (Box 23-3) such as the classic 479 Harris-Benedict equation estimate daily resting energy expenditure (REE) Several other predictive equations focus on specific patient populations and medical conditions Additional data such as injury-stress, activity, medications received, and obesity have been added to improve accuracy The Mifflin-St Jeor equation is the most reliable in both nonobese and obese ill patients.28 Other equations, such as the Ireton-Jones and Penn State equations are used specifically in intubated patients to account for temperature and ventilation parameters Although the predicted REE averages approximately 10% higher than the BMR, predictive equations may still tend to overestimate or underestimate actual energy need.29 Box 23-3 Predictive Equations HARRIS-BENEDICT EQUATIONS Men: Resting metabolic rate (RMR) = 66.47 + 13.75(W) + 5(H) − 6.76 (A) Women: RMR = 655.1 + 9.56 (W) + 1.7 (H) − 4.7 (A) Equation uses weight (W) in kilograms (kg), height (H) in centimeters (cm), and age (A) in years IRETON-JONES ENERGY EQUATIONS (IJEE) 1992 Spontaneously breathing IJEE (s) = 629 − 11 (A) + 25 (W) − 609 (O) Ventilator dependent IJEE (v) = 1925 − 10 (A) + (W) + 281 (S) + 292 (T) + 851 (B) Equations uses age (A) in years, body weight (W) in kilograms, sex (S, male = 1, female = 0), diagnosis of trauma (T, present = 1, absent = 0), diagnosis of burn (B, present = 1, absent = 0), obesity more than 30% above initial body weight from 1959 Metropolitan Life Insurance tables or body mass index (BMI) more than 27 kg/m2 (present = 1, absent = 0) MIFFLIN-ST JEOR EQUATIONS Box 23-2 Factors Influencing Energy and Macronutrient Needs ENERGY NEEDS • • • • • • • Height and weight Activity level Growth state: Infants through teens, pregnancy, and lactation Presence of infection or fever Surgery Trauma and fractures Presence of infection or inflammation PROTEIN NEEDS • • • • • State of growth Surgery, trauma, fractures, and infection Renal (kidney) function Liver function Corticosteroid administration FAT NEEDS • • • • Total energy needs Hyperlipidemia, and diabetes mellitus Liver, gallbladder, and pancreatic disorders Cardiovascular disease Men: RMR = (9.99 × weight) + (6.25 × height) − (4.92 × age) + Women: RMR = (9.99 × weight) + (6.25 × height) − (4.92 × age) − 161 Equations use weight in kilograms and height in centimeters PENN STATE EQUATIONS (PSU) Also known as PSU 2010 (Modified Penn State Equation) RMR = Mifflin ( 0.71) + VE ( 64 ) + Tmax ( 85 ) − 3085 Used for patients with BMI over 30 and older than 60 years old Validated in 2010 by the ADA Evidence Analysis Library (EAL) PSU 2003b (Penn State Equation) RMR = Mifflin ( 0.96 ) + VE ( 31) + Tmax (167) − 6212 Used for patient of any age with BMI below 30 or patients who are younger than 60 years with BMI over 30 This equation was validated in 2009 by the EAL and is also referred to as the Penn State equation PSU 2003a (Penn State 2003a) Invalidated in 2007 and 2009 by EAL RMR = HBE ( 0.85 ) + VE ( 33 ) + Tmax (175 ) − 6433 (Use actual weight in all patients.) From Academy of Nutrition and Dietetics Evidence analysis library, 2014 Available http://www.andeal.org Accessed September 2014 480 SECTION III • Assessment of Respiratory Disorders To overcome the limitations of estimating formulas, energy needs can be measured using O2 consumption and carbon dioxide production From these data, an actual REE can be quickly computed Indirect calorimetry is described in more detail later Energy needs vary according to activity level and state of health Energy needs of sick patients can be significantly greater than predicted normal values Energy needs for obese individuals are less because adipose tissue uses less energy than muscle Energy needs should be reevaluated and adjusted whenever weight changes more than 10 lb RULE OF THUMB To estimate the energy needs of an average adult in kilocalories per day, identify the goal and multiply the individual’s actual body weight in kilograms times the factor listed as follows27: Goal Energy Needs (kcal/kg) Weight maintenance Weight gain Weight loss 25-30 30-35 20-25 Indirect Calorimetry Indirect calorimetry is the estimation of energy expenditure by measurement of O2 consumption and CO2 production Data obtained can be used to assess a patient’s metabolic state, to determine nutrition needs, or to assess response to nutritional therapy.30 To guide practitioners in using indirect calorimetry, the American Association for Respiratory Care (AARC) has published the Clinical Practice Guideline: Metabolic Measurement Using Indirect Calorimetry During Mechanical Ventilation Excerpts appear in Clinical Practice Guideline 23-1.31 In regard to the indications for indirect calorimetry, the determination of energy and protein needs by an empiric formula is sufficient for most patients However, the use of indirect calorimetry improves nutritional care and reduces complications associated with underfeeding and overfeeding.30 Specific clinical conditions supporting the need for indirect calorimetry as a tool in nutrition assessment are listed in Box 23-4.30 Box 23-4 • • • • • • • Patients Patients Patients Patients Patients Patients Patients Clinical Situations in Which Indirect Calorimetry May Be Indicated with morbid obesity who are difficult to wean from ventilatory support for whom weight estimates are unclear with severe malnutrition with high level of stress at the extremes of weight or age failing to respond to nutrition support Equipment and Technique Good calorimetry results require extensive preparation Box 23-5 outlines the key preparatory steps to be taken before testing.32 Indirect calorimetry can be performed with a Douglas bag, a Tissot spirometer, and CO2 and O2 gas analyzers The patient’s expired gas is collected in the Douglas bag, where it is sampled for O2 and CO2 concentrations; the Tissot spirometer measures expired volume Commercially available metabolic carts are much easier to use These automated systems either use a mixing chamber or perform breath-by-breath analysis The breath-by-breath method provides real-time data, which may aid in ensuring optimal measurement conditions, particularly in mechanically ventilated patients.33 Figure 23-1 shows the basic configuration for open-circuit indirect calorimetry during mechanical ventilation using a metabolic cart with mixing chamber Gas sampled from the inspiratory limb of the ventilator circuit is assessed for fractional inspired oxygen (FiO2) using a paramagnetic or zirconium oxide O2 analyzer Volume exhaled by the patient is measured using a flow transducer The patient’s exhaled gas enters a mixing chamber, from which a sample is drawn to measure fractional expired carbon dioxide (FeCO2) by infrared analysis and fractional expired oxygen (FeO2) Exhaled gas is returned to the ventilator after volume and gas concentration measurements After all measurements are obtained, O2 consumption, CO2 production, and respiratory quotient (RQ) are computed using the equations shown in Box 23-6 All measurements must be corrected to standard temperature and pressure and dry conditions (STPD) before computation.31 The values are used in the abbreviated Weir equation to determine REE: REE = [(O2 × 3.9) + (CO2 × 1.1)] × 1.44 Box 23-5 Preparation for Indirect Calorimetry 30 HOURS BEFORE TEST • 24-Hour urine urea nitrogen collection (with sufficient time to receive result) if determination of carbohydrate, fat, and protein use desired 10 HOURS BEFORE TEST • Patient fasting if measuring energy requirements; if feeding is continued, results will reflect the patient’s energy expenditure in response to feeding (may be spuriously high if patient is being overfed) HOURS BEFORE TEST • Patient resting and avoiding physical activity, physical therapy, dressing changes HOURS BEFORE TEST • Endotracheal tube suctioned for the last time before test; further ventilator changes or suctioning avoided HOUR BEFORE TEST • Supine position, complete rest; analgesic or sedative administered if needed Nutrition Assessment • CHAPTER 23 23-1 481 Metabolic Measurement Using Indirect Calorimetry During Mechanical Ventilation AARC Clinical Practice Guideline (Excerpts)* ■ INDICATIONS Metabolic measurements may be indicated: • In patients with known nutrition deficits or derangements • When patients fail attempts at weaning from mechanical ventilation to measure the O2 cost of breathing in mechanically ventilated patients • When the need exists to assess the V/Q2 to evaluate the hemodynamic support of mechanically ventilated patients ■ CONTRAINDICATIONS When a specific indication is present, there are no contraindications to performing a metabolic measurement using indirect calorimetry, unless short-term disconnection of ventilatory support for connection of measurement lines results in hypoxemia, bradycardia, or other adverse effects ■ HAZARDS AND COMPLICATIONS Performing metabolic measurements using an indirect calorimeter is a safe, noninvasive procedure with few hazards or complications Under certain circumstances and with particular equipment, the following hazards or complications may be seen: • Closed-circuit calorimeters may cause a reduction in alveolar ventilation secondary to increased compressible volume of the breathing circuit • Closed-circuit calorimeters may decrease the trigger sensitivity of the ventilator and result in increased patient work of breathing • Short-term disconnection of the patient from the ventilator for connection of the indirect calorimetry apparatus may result in hypoxemia, bradycardia, and patient discomfort • Inappropriate calibration or system setup may result in erroneous results causing incorrect patient management ■ ASSESSMENT OF NEED Metabolic measurements should be performed only on the order of a physician after review of indications (see earlier) and objectives ■ ASSESSMENT OF TEST QUALITY Test quality can be evaluated by determining whether: • Respiratory quotient is consistent with the patient’s nutrition intake • Respiratory quotient is in the normal physiologic range (0.67 to 1.3) • Variability of the measurements of VO2 and VCO2 should be 5% or less for a 5-minute data collection • The measurement is of sufficient length to account for variability in VO2 and VCO2 if these conditions are not met • Outcome may be assessed by comparing the measurement results with the patient’s condition and nutrition intake Outcome also may be assessed by observation of the patient before and during the measurement to determine if the patient is at steady state ■ MONITORING The following should be evaluated during the metabolic measurement to ascertain the validity of the results: • Clinical observation of the resting state • Patient comfort and movement during testing • Values in concert with the clinical situation • Equipment function • Results within the specifications of test quality (see earlier) • FiO2 stability Measurement data should include a statement of test quality and list the current nutrition support, ventilator settings, FiO2 stability, and vital signs *For the complete guidelines, see American Association of Respiratory Care: Clinical practice guideline Respir Care 49:1073, 2004 http://www.rcjournal.com/ contents/09.04/09.04.1073.pdf Accessed June 1, 2014 Box 23-6 Equations Used to Calculate VO2 and VCO2 Using the Gas-Exchange Method VO2 = VE × ( FiO2 ) − ( VE × FeO2 ) VCO2 = VE × FeCO2 RQ = VCO2 /VO2 Indirect calorimetry is more difficult to perform on spontaneously breathing patients, especially patients breathing supplemental O2 Although a mouthpiece with nose clips or a mask can be used to collect expired gas, these items tend to alter the patient’s steady state and invalidate results.33 Instead, most clinicians recommend using a plastic canopy that covers the patient’s head Expired gases are cleared from the canopy by a preset flow of air; expired gas concentrations are sampled and corrected for the air dilution Because standard modes of O2 therapy not deliver a consistent FiO2 to spontaneously breathing patients, special delivery systems must be used To overcome this problem, the clinician can substitute a precise O2 mixture for the gas used to clear the canopy Alternatively, a large gas reservoir (e.g., a Douglas bag) can be placed between an O2 flow source and the subject33 to ensure a stable FiO2 throughout the test procedure Problems and Limitations Indirect calorimetry is a technically complex procedure requiring rigorous attention to both instrument and procedure quality 482 SECTION III • Assessment of Respiratory Disorders 180 FiO2 Ventilator O2 Analyzer CO2 Analyzer Patient FeO2 FeCO2 VE Volume monitor Mixing Resting Energy Expenditure (% Normal) Blender Chamber FIGURE 23-1 Open-circuit indirect calorimetry in a mechanically ventilated patient Inspiratory gas is sampled for determination of FiO2, volume is measured in the expiratory limb of the ventilator circuit, and mixed exhaled gas is drawn from the mixing chamber for analysis of FeO2 and FeCO2 Arrows indicate direction of gas flow (Modified from Witte MK: Metabolic measurements during mechanical ventilation in the pediatric intensive care unit Respir Care Clin N Am 2:573, 1996.) 170 160 150 140 130 120 110 100 90 Interpretation and Use of Results Results obtained from indirect calorimetry are used to assess metabolic status and plan nutrition support Energy expenditure varies during illness and injury (Figure 23-2),34 which occurs in three phases: the stress response, the catabolic phase and the anabolic phase Because of the changing metabolic rate, it is important to reassess metabolic needs when there is a 15 Days Moderate/Severe Burn Minor Surgery 20 25 30 Skeletal Trauma Normal (Baseline) FIGURE 23-2 Resting energy expenditure variation during illness and injury Box 23-7 control Regarding instrumentation, small errors in measurements can result in large errors in calculated O2, CO2, and therefore energy expenditure For this reason, the calorimeter’s gas analyzers and volume measurement device must be properly calibrated before each patient use Gas analyzers should be accurate to the hundredth percent and linear over the clinical range of O2 concentrations.32 Regarding procedure quality control, it is essential that measurements be made during steady-state conditions Although proper patient preparation (see Box 23-5) is helpful in this regard, steady-state conditions can be confirmed only during the test procedure itself A common standard for ensuring steady-state conditions is five consecutive 1-minute averages with a variability of 5% or less.33 Perhaps the most significant problem in performing indirect calorimetry on mechanically ventilated patients is the presence of leaks (circuit, tracheal tube cuff, chest tubes).31 Because any leak invalidates test results, no procedure should begin until a leak-free patient-ventilator-calorimeter system is confirmed Other sources of error during open-circuit indirect calorimetry of mechanically ventilated patients are listed in Box 23-7.31 10 • • • • • • • • • Sources of Error During OpenCircuit Indirect Calorimetry of Mechanically Ventilated Patients Instability of FiO2 because of changes in source gas pressure or ventilator or blender variability Delivery of high FiO2 levels (>0.60) Inability to separate inspired and expired gases because of bias flow from flow-triggering systems, intermittent mandatory ventilation systems, or specific ventilator characteristics Presence of anesthetic gases or gases other than O2, CO2, and nitrogen in the ventilation system Presence of water vapor resulting in sensor malfunction Inappropriate calibration Adverse effect on functions of some ventilators (triggering, expiratory resistance, pressure measurement) Total circuit flow exceeding internal calorimeter flow (if using dilutional principle) Concurrent peritoneal dialysis or hemodialysis change in clinical status Indirect calorimetry is an important tool because it can demonstrate these changes in energy expenditure Energy expenditure can vary on a daily basis by 15% to 30%.33 In regard to assessing metabolic status, the first step is to compare the REE obtained by calorimetry with the REE predicted by predictive equations If the calorimetry REE is within 10% of the predicted value, the patient is considered normometabolic Measured REEs greater than 10% above predicted values indicate a hypermetabolic state, whereas values less than 90% of predicted indicate hypometabolism Nutrition Assessment • CHAPTER 23 should be used only as a measure of test validity If the RQ is outside its physiologic range of 0.67 to 1.3, this should alert the clinician to assess the validity of the study TABLE 23-3 Traditional Interpretation and Use of the Respiratory Quotient Value Interpretation General Nutrition Strategy >1.00 0.9-1.00 Overfeeding Carbohydrate oxidation 0.8-0.9 Fat, protein, and carbohydrate oxidation Fat and protein oxidation Starvation Decrease total kilocalories Decrease carbohydrates or increase lipids Target range for mixed substrate Increase total kilocalories 0.7-0.8 483 NOTE: Acute hyperventilation or acute metabolic acidosis increases the respiratory quotient (RQ) and can lead to misinterpretation Metabolism of ketones or ethyl alcohol decreases RQ to less than 0.7 The second step in metabolic assessment is to interpret the RQ The RQ is the ratio of moles of CO2 expired to moles of O2 consumed Traditionally, the RQ has been used to determine substrate use, where carbohydrates have an RQ of 1.0, protein has an RQ of 0.82, and fat has an RQ of 0.7 Table 23-3 outlines the basic significance of the RQ relative to substrate use and traditional nutrition strategies.33 RQ has been shown to have low sensitivity and reduced specificity in critically ill patients.35,36 This finding limits the RQ as an indicator for substrate use and RULE OF THUMB RQ 0.67 to 1.3 Ideal range for test validity Alternative Resting Energy Expenditure Measures In patients with pulmonary artery catheters, REE can be measured using a modification of the Fick equation37: REE (kcal day ) = Cardiac output × Hemoglobin × (SaO2 − SvO2 ) × 95.18 In a patient with cardiac output of 4.2 L, hemoglobin of 11 g/ dl, SaO2 of 89%, and SVO2 of 69%, the REE would be computed as follows: REE = 4.2 × 11 × (0.89 − 0.69) × 95.18 REE = 4.2 × 11 × (0.20) × 95.18 REE = 879 kcal day M I N I CLINI Comparison of Resting Energy Expenditure from Predictive Equations and Indirect Calorimetry PROBLEM: A 57-year-old male construction worker fell three stories and after being intubated and mechanical ventilation initiated was admitted to the intensive care unit for multiple orthopedic injuries, several rib fractures, and a pulmonary contusion On hospital day 2, after the patient was stabilized, a nasogastric feeding tube was placed and a nutrition consult was requested for enteral nutrition recommendations Anthropometrics: Height: ft, inches; measured body weight: 127.3 kg; BMI: 43.8 kg/m2 The dietitian used and compared the follow predictive equations to determine the patient’s energy expenditure: Predictive Equation: Harris-Benedict × 1.3-1.6* Mifflin-St Joer × 1.3 Ireton-Jones Penn State kcal/day 2269-2792 2718 3081 2137 *Factor to correct for stress and/or activity levels The initial goal recommended by the dietitian for the tube feeding would provide 2280 calories An indirect calorimetry study was also requested by the dietitian because the patient is a perfect candidate for the indirect calorimetry because of his BMI and clinical status The indirect calorimetry study was conducted on a weekly basis and the results were as follows: Hospital Day 10 17 Measured Metabolic Rate (kcal/day) RQ 1980 3150 2700 1.1 0.83 0.85 Interpret the results and compare to the predictive equations Based on the results, suggest what changes would be made DISCUSSION: The following conclusions can be made based on retrospective data review Overall, the predictive equations estimations vary widely Initially the Penn State equation was the most accurate equation compared to the indirect calorimetry study results The RQ is within physiologic range of 0.67 to 1.3, suggesting a valid study; however, it further indicates the patient is possibly being overfed As a result the tube feed goal was adjusted to provide 1980 calories to match the patient’s current metabolic phase However, as the patient moved into the catabolic phase, if the patient continued to receive 2280 calories as initially recommended by the dietitian (or the adjusted level of 1980 calories) and subsequent indirect calorimetry was not done on day 10, resulting in a tube feed increase to 3150 calories, the patient would be significantly underfed Finally, entering into the anabolic phase, the patient’s energy expenditure begins to decrease, as shown by the indirect calorimetry on day 17 As a result, the tube feed regimen should be further adjusted (decreased) to match the measured metabolic rate Modified from Wooley JA, Frankenfield D: Energy In: Mueller CM, Merritt RJ, McClave S, et al, editors: The ASPEN adult nutrition support core curriculum, ed 2, Silver Spring, MD, 2012, American Society for Parenteral and Enteral Nutrition 484 SECTION III • Assessment of Respiratory Disorders RULE OF THUMB Although predictive equations are highly useful tools in calculating a patient’s energy expenditure needs, they not always replace the need for performing indirect calorimetry, which is generally more accurate and provides additional information, including calculation of the RQ GENERAL ASPECTS OF NUTRITION SUPPORT The primary goal of nutrition support is the maintenance or restoration of lean body (skeletal muscle) mass This goal is accomplished by (1) meeting the patient’s overall energy needs and (2) providing the appropriate combination of substrates to so The route of administration used to provide the support is also important Meeting Overall Energy Needs When the patient’s REE is derived, it needs to be adjusted to account for variations in activity and stress levels If using a predictive equation, such as the Harris-Benedict or Mifflin-St Joer equations, the predicted REE should be corrected for stress, activity levels, or both.20 When the REE is derived from the Penn State equations or indirect calorimetry, a stress or activity factor should not be used Insufficient Energy Consumed Malnutrition from undernutrition results from insufficient energy (calorie) intake over time This insufficient intake leads to a state of impaired metabolism in which the intake of essential nutrients falls short of the body’s needs Certain factors may place a patient at risk for malnutrition (Box 23-8) Protein-Energy Malnutrition Protein-energy malnutrition (PEM) has adverse effects on respiratory musculature and the immune response.24 PEM may Box 23-8 • • • • • • Patients at High Risk for Malnutrition Underweight (BMI 100 mg/dl).14 Too much protein is harmful, especially for patients with limited pulmonary reserves Excess protein can increase O2 consumption, REE, minute ventilation, and central ventilatory drive.43 In addition, overzealous protein feeding may lead to symptoms such as dyspnea Box 23-12 Carbohydrate Carbohydrates are the main source of fuel for the body Adequate amounts of carbohydrates and fat help prevent protein catabolism Glucose (dextrose) is the most commonly administered intravenous carbohydrate Total calories per day from carbohydrates can range from 45% to 65% In an averagesized patient, daily glucose provision is generally estimated at 200 g/day.44 For patients with pulmonary disease or patients requiring mechanical ventilation, high carbohydrate loads were initially blamed for increased CO2 production and the RQ, resulting in increased ventilatory demand, O2 consumption, and work of breathing.45 More recent evidence indicates that this problem is probably more closely related to total calorie load (overfeeding) than to the proportion of carbohydrate in the diet.46,47 Therefore overfeeding should be carefully avoided in patients with pulmonary disease and patients requiring mechanical ventilation • Fat The remaining calories (20% to 30%) should be provided from fat.48 A minimum of 2% to 4% is needed to prevent essential fatty acid deficiency Fat intakes greater than 50% of energy needs are associated with fever, impaired immune function, liver dysfunction, and hypotension.14 The initiation of nutrition support is determined by the patient’s nutrition status and the estimated length of time the patient will be unable to consume a diet by mouth to meet nutrition needs To ensure satisfactory nutrition and metabolic response, early enteral nutrition begun within 24 to 48 hours provides significant benefits to critically ill patients, including reduced infectious complications and lengths of stay.49 RULE OF THUMB Begin enteral nutrition within 24 to 48 hours of intubation ROUTES OF ADMINISTRATION The two primary routes for supplying nutrients to patients are enteral (oral and tube feeding) and parenteral (peripheral or central venous alimentation) Box 23-12 provides guidelines for Guidelines for Initiation of Nutrition Support CLINICAL SETTINGS IN WHICH ENTERAL NUTRITION SHOULD BE PART OF ROUTINE CARE • • • • • • Protein-calorie malnutrition (>10% loss of usual weight) with inadequate oral intake of nutrients for previous to days Normal nutritional status with less than 50% of required nutrient intake orally for previous to 10 days Severe dysphagia Moderate to severe pancreatitis (bowel rest anticipated beyond to days) Burns of greater than 15% total BSA in infants and children and greater than 25% total BSA in older children and adults Massive small bowel resection in combination with administration of total parenteral nutrition Low output (