Blood Gases and Critical Care Testing : Physiology, Clinical Interpretations, and Laboratory Applications

Blood gas tests are a group of tests that are widely used and essential for the evaluation and management of a patient’s ventilation, oxygenation, and acid-base balance, often in emergent situations, and along with blood gases are other critical care analytes measured on blood: calcium, magnesium, phosphate, and lactate. __Blood Gases and Critical Care Testing: Clinical Interpretations and Laboratory Applications, Third Edition__, serves as your single most important reference for understanding blood gases and critical care testing and interpretation. The third edition of this classic book is a complete revision and provides the fundamentals of blood gas (pH, pCO2, pO2) and other critical care tests (calcium, magnesium, phosphate, and lactate), including the history, the definitions, the physiology, and practical information on sample handling, quality control and reference intervals. Case examples with clear clinical interpretations of critical care tests have been included to all chapters. This book will serve as a valuable and convenient resource for clinical laboratory scientists in understanding the physiology and clinical use of these critical care tests and for providing practical guidelines for successful routine testing and quality monitoring of these tests. Blood Gases and Critical Care Testing Copyright About the authors Preface to third edition 1. Introduction to blood-gas tests and blood-gas physiology Introduction and history of blood gases Explanations of blood gas, acid–base, and cooximetry terms Anion gap Delta gap and delta ratio Strong ion difference Hemoglobin and derivatives sO2 and %O2Hb COHb and metHb DO2 and VO2 Physiology of acid and base production Buffer systems Acid–base regulation Hemoglobin function Reference intervals for blood gases Self-assessment and mastery Answer Key: References 2. Physiologic mechanisms and diagnostic approach to acid–base disorders Metabolic acidosis Metabolic alkalosis Respiratory acidosis Respiratory alkalosis Detecting mixed acid–base disorders Does the expected compensation occur? Diagnostic approach to acid–base disorders Reference intervals Stepwise approach to evaluating acid–base status Step 1. Evaluate the patient's clinical history and status to anticipate possible acid–base disorders Step 2. Evaluate the pH Step 3. Evaluate the ventilatory and metabolic status Step 4. Evaluate laboratory and clinical data for a possible mixed disorder Step 4a. Is the compensation appropriate for the primary disorder? Step 4b. Do other laboratory results suggest an additional acid–base disorder is present? Step 4c. Does the patient have other conditions associated with an acid–base disorder? Summary of acid–base (pH, pCO2, and HCO3−) interpretations Complex acid–base case example (9) Self-assessment and mastery Case examples References 3. Interpreting blood gas results on venous, capillary, and umbilical cord blood Physiologic differences between arterial and venous blood for blood gas and acid–base measurements Interpretation of venous blood gas values Capillary blood gases (neonatal) How much are capillary blood gas results compromised? Umbilical cord blood gases Blood circulation in the fetus and placenta Acid–base physiology in the fetus Clinical uses of umbilical cord blood gas results Clinical uses of umbilical cord blood lactate results Reference intervals for umbilical arterial and venous cord blood Collecting umbilical cord blood specimens References 4. Disorders of oxygenation: hypoxemia and tissue hypoxia Introduction Parameters in oxygen monitoring Structure and function of hemoglobin Processes in oxygen transport and delivery to tissues and mitochondria Evaluation of hypoxemia Measured and calculated parameters for evaluating arterial oxygenation Methodology of oxygen measurements Self-assessment and mastery Self-assessment questions Self-assessment questions answer key Self-assessment cases and discussion References 5. Calcium physiology and clinical evaluation Introduction and history Calcium physiology Regulation in the blood Hormonal regulation of calcium Distribution in cells and blood Hypocalcemia Signs and symptoms of hypocalcemia Causes of hypocalcemia Laboratory evaluation of hypocalcemia Total calcium, “corrected” total calcium, and ionized calcium Treatment of hypocalcemia Hypercalcemia Signs and symptoms of hypercalcemia Causes of hypercalcemia Treatment of hypercalcemia Interpretation of calcium and PTH measurements Proper collection and handling of samples Reference intervals for calcium Self-assessment Self-assessment questions Answer Key: Self-assessment cases Self-assessment and mastery discussion References 6. Magnesium physiology and clinical evaluation Introduction Magnesium distribution and regulation in the blood Physiology Hypomagnesemia Causes and clinical conditions associated with hypomagnesemia Critical illness Cardiac disorders Drugs Diabetes Dietary deficiency Alcoholism Cellular hypoxia Preeclampsia of pregnancy Diarrhea Burns PTH deficiency Other diseases Biochemical manifestations of hypomagnesemia Evaluation of magnesium status in patients Treatment of hypomagnesemia Hypermagnesemia Causes of hypermagnesemia Symptoms of hypermagnesemia Treatment of hypermagnesemia Proper collection and handling of samples Diagnosis of magnesium abnormalities Ionized Mg versus total Mg Reference intervals for magnesium Self-assessment and mastery Self-assessment questions Answer Key: Self-assessment cases Self-assessment and mastery discussion References 7. Phosphate physiology and clinical evaluation Introduction Distribution in cells and blood Physiology and regulation Cellular transport Factors that affect renal absorption of PO4 Hypophosphatemia Causes of hypophosphatemia Symptoms of hypophosphatemia Evaluation of hypophosphatemia Treatment of hypophosphatemia Hyperphosphatemia Causes of hyperphosphatemia Symptoms of hyperphosphatemia Evaluation of hyperphosphatemia Treatment of hyperphosphatemia Reference intervals Self-assessment and mastery Self-assessment questions Self-assessment cases Self-assessment and mastery discussion References 8. Osmolality, sodium, potassium, chloride, and bicarbonate Osmolality and volume regulation Introduction Calculation of osmolality Regulation of osmolality Regulation of blood volume Reference interval Sodium Physiology of sodium balance Frequency of hyponatremia and hypernatremia Hyponatremia Causes of hyponatremia Laboratory evaluation of hyponatremia Clinical diagnosis of hyponatremia Treatment of hyponatremia Hypernatremia Causes of hypernatremia Laboratory and clinical evaluation of hypernatremia Treatment of hypernatremia Potassium Physiology Regulation Hypokalemia Causes of hypokalemia Symptoms of hypokalemia Laboratory evaluation of hypokalemia Treatment of hypokalemia Hyperkalemia Causes of hyperkalemia Clinical effects of hyperkalemia Laboratory evaluation of hyperkalemia Treatment of hyperkalemia Proper collection and handling of samples Chloride Physiology and regulation Causes of hypochloremia and hyperchloremia Bicarbonate Physiology and regulation Causes of decreased and increased bicarbonate Self-assessment and mastery Self-assessment and mastery discussion References 9. Lactate physiology and diagnostic evaluation Introduction Physiology and metabolism Causes of hyperlactatemia Blood lactate in sepsis Clinical approach to monitoring blood lactate Basic treatment strategies for elevated blood lactate Proper collection and handling of specimens for lactate testing Reference intervals for blood lactate Self-assessment Self-assessment questions Answer Key: Case examples References 10. Collection and handling of samples: effects on blood gases, Na, K, ionized Ca, Mg, lactate, and phosphate analyses Sources of preanalytical errors in blood gas and electrolyte testing Introduction Hemolysis Proper collection and handling of samples Blood gases Collection and transport of blood for oxygen measurements Sodium Potassium Ionized calcium Effects of anticoagulants and clotting on ionized calcium concentrations Physiological and preanalytical changes to ionized calcium concentrations Lactate Phosphate Magnesium Self-assessment questions Answer Key: References 11. Quality control in blood gas and critical care testing Routine daily quality control on blood gas instruments Individualized Quality Control Plan Between-lab and between-instrument QC Detection of hemolysis in whole blood specimens References 12. Models for point-of-care testing of critical care analytes Introduction Importance of POCT in answering clinical needs Types of POCT analyzers Selecting an analyzer for POCT Analyzer quality for POCT Information connectivity and data management Cost analysis for handheld versus hybrid analyzers Quality control techniques for POC testing Meeting compliance requirements by regulatory agencies Training and continuing compliance Case example: decisions in implementing a POCT system What needs are not met by central lab testing? What will be improved by implementing POCT? What are the training needs and additional staffing needs of both the POC users and the laboratory? End-user acceptability of responsibilities. Is there buy-in not only from the managers of the care units, but from those wh ... Continual communication with users and having a supportive point person What are the start-up and operating costs? How complex and technically difficult is the device for POC testing? Does the sy ... What are the space needs, including electrical and informatics connections? Who will do maintenance and troubleshooting? References Blood gas tests are a group of tests that are widely used and essential for the evaluation and management of a patient's ventilation, oxygenation, and acid-base balance, often in emergent situations, and along with blood gases are other critical care analytes measured on blood: calcium, magnesium, phosphate, and lactate. Blood Gases and Critical Care Testing: Clinical Interpretations and Laboratory Applications, Third Edition, serves as your single most important reference for understanding blood gases and critical care testing and interpretation. The third edition of this classic book is a complete revision and provides the fundamentals of blood gas (pH, pCO2, pO2) and other critical care tests (calcium, magnesium, phosphate, and lactate), including the history, the definitions, the physiology, and practical information on sample handling, quality control and reference intervals. Case examples with clear clinical interpretations of critical care tests have been included to all chapters. This book will serve as a valuable and convenient resource for clinical laboratory scientists in understanding the physiology and clinical use of these critical care tests and for providing practical guidelines for successful routine testing and quality monitoring of these tests. Provides a step-by-step approach for organizing and evaluating clinical blood gas and critical care test results Describes several calculated parameters that are used by clinicians for evaluating a patient's pulmonary function and oxygenation status and discusses clinical examples of their use This new edition includes more detailed information about reference intervals, not only for arterial blood, but for venous blood and umbilical cord blood, and for pH in body fluids Covers practical information on sample handling and quality control issues for blood gas testing This is now the third edition of my book that was titled Blood Gases andElectrolytes. The dramatic changes in the world of critical care testing were theimpetus for a new edition with a new title. Indeed, the first edition of the bookseems from a different universe. As I recall, the main topic was how to measurephlogiston on a Van Slyke apparatus and how to treat hypophlogistonemia. Thesecond edition was better, but critical care testing has continued to change in thepast 12 years since, so this third edition is a thoroughly updated versiondeserving a new title. In addition to updated chapters on clinical interpretationsof blood gases and electrolytes (Ca, Mg, Na, K, and PO4), it includes entirelynew chapters on blood gas testing on venous, capillary and umbilical cord blood,the evolving role of blood lactate testing in critical care, proper sample collectionand handling to avoid preanalytical variation, and chapters on point-of-caretesting and quality control for these tests.