Laboratory Testing in the Intensive Care Unit
Section snippets
Scope and cost of laboratory testing
Laboratory testing is ubiquitous among hospitalized patients. Patients in intensive care units (ICUs) are subject to a higher number of blood draws, resulting in greater blood loss per day and greater phlebotomy during the entire hospitalization. Patients with arterial lines; those in teaching rather than nonteaching ICUs; and patients with higher severity of illness and specific diagnoses, such as sepsis, have more frequent laboratory testing and phlebotomy [1], [2]. There is also considerable
Reference intervals and what is “normal”
In most instances, a reference interval is developed from a cohort of individuals without apparent disease. All members of the cohort undergo testing, and the central 95% of the results are determined. Therefore, by definition, 5% of a “normal” population has test results outside of the reference interval. There is an obvious limitation in equating values outside of this range to the presence of disease. In addition, considerations of inherent biologic variation, interindividual differences,
Context of laboratory testing in the intensive care unit
The authors are unaware of an existing exploration of indications for laboratory testing in the ICU. They suggest the framework outlined in Table 3. Indications for testing are classified, based on the pretest probabilities of true abnormalities requiring intervention (for ease of discussion, the authors refer to these abnormalities requiring intervention as “disease”). Screening tests are those performed because a condition occurs within a patient population without any suggestion that the
Screening and homeostatic testing
On the basis of the authors' framework, screening and homeostatic laboratory tests are those performed when the pretest probability of disease for an individual patient is not appreciably different than that for the general population. Because laboratory results in the critically ill are more likely to be outside of a reference interval [21], this raises the pretest probability of abnormal test results in patients in the ICU. Unlike ambulatory patients, many patients in the ICU cannot
Risks of laboratory testing
Considering laboratory testing as part of therapy frames the decision to proceed with testing in the context of the balance between potential benefits and risks. A useful laboratory test should have the potential to alter the management plan for a patient. If a laboratory test can only detect disease for which there are no therapeutic options, the test should not be performed. Therapeutic options need not be curative or disease directed. Confirmation of a fatal disease that may be appropriately
Recommendations for “routine” laboratory testing: screening and homeostatic laboratory tests
It has traditionally been assumed that because they have higher severity of illness, critically ill patients require more frequent determination of laboratory values [17]. Several observations suggest that the current intensity of laboratory testing is excessive, however. When “routine” laboratory tests are canceled by a protocol, clinicians rarely override the cancellation, and when unexpected abnormal values are encountered, they are often ignored [51], [52]. Use of laboratory testing varies
Strategies to reduce unneeded laboratory tests
Multiple strategies have been used in an effort to reduce laboratory testing and to ensure that ordered tests are appropriate for the clinical syndrome under investigation. These have included suggestions by pharmacists on rounds to reduce phlebotomy [63], a laboratory interpretation and consultative service [64], changes in processes of test ordering [17], [19], [65], [66], the use of guidelines for laboratory testing [16], [17], [18], [19], [20], [66], and providing physicians with prices of
Cardiac biomarkers in critical illness: troponin and natriuretic peptides
Assays for troponin isoforms and brain natriuretic peptide (BNP) and variants (eg, N-terminal [NT]–pro-BNP) have received attention as potentially useful diagnostic and prognostic tests in critically ill patients. The increasing popularity of these tests stems from the ease with which they can be obtained as well as their proven utility as diagnostic tests outside of the ICU. In patients presenting with symptoms of myocardial infarction, troponin assays are sensitive and highly specific tests
Point-of-care testing
Caring for critically ill patients involves medical decision making that can be time-sensitive, and information crucial to these decisions may be needed within minutes. As patient acuity increases, the need for rapid collection, processing, and interpretation of laboratory tests becomes more urgent. For these reasons and others, point-of-care (POC) technologies have become a considered alternative for critical care medicine. POC refers to the performance of diagnostic tests at or near the
Suggestions for future research and current practice
As outlined throughout, there are few data to guide clinicians in regard to laboratory testing in critically ill patients. Patients in the ICU have significantly more testing performed than any other single group of patients. This testing is not without risk, ranging from ICU-acquired anemia to misguided decision making. Multiple studies found that the volume of testing can be dramatically reduced without appreciably affecting outcomes. This suggests that at least a portion of the current
Summary
Laboratory testing in critically ill patients represents a large proportion of the cost of caring for these patients. Much of this testing seems to be unsupported by evidence of efficacy and often does not lead to meaningful changes in therapy. The unnecessary risks and costs of excessive laboratory testing in the ICU could be minimized by a carefully developed framework of accepted or suggested laboratory tests for critically ill patients, supplemented by investigations to determine the
References (121)
Frequency of laboratory test utilization in the intensive care unit and its implications for large-scale data collection efforts
J Am Med Inform Assoc
(2005)- et al.
The APACHE III prognostic system. Risk prediction of hospital mortality for critically ill hospitalized adults
Chest
(1991) - et al.
The simultaneous measurement of ionized and total calcium and ionized and total magnesium in intensive care unit patients
J Crit Care
(2002) - et al.
Anemia, allogenic blood transfusion, and immunomodulation in the critically ill
Chest
(2005) - et al.
Reduction of blood loss from diagnostic sampling in critically ill patients using a blood-conserving arterial line system
Chest
(1993) - et al.
Effect of anaemia and cardiovascular disease on surgical mortality and morbidity
Lancet
(1996) Blood transfusion in the critically ill patient
Dis Mon
(1999)- et al.
What proportion of common diagnostic tests appear redundant?
Am J Med
(1998) Pulse oximetry in severe carbon monoxide poisoning
Chest
(1998)- et al.
Common causes of troponin elevations in the absence of acute myocardial infarction: incidence and clinical significance
Chest
(2004)
Troponin as a risk factor for mortality in critically ill patients without acute coronary syndromes
J Am Coll Cardiol
Relationship between B-type natriuretic peptides and pulmonary capillary wedge pressure in the intensive care unit
J Am Coll Cardiol
Utility of B-type natriuretic peptide and N-terminal pro B-type natriuretic peptide in evaluation of respiratory failure in critically ill patients
Chest
Comparative accuracy of B-type natriuretic peptide and tissue Doppler echocardiography in the diagnosis of congestive heart failure
Am J Cardiol
D-dimer plasma concentration in various clinical conditions: implication for the use of this test in the diagnostic approach of venous thromboembolism
Thromb Res
D-dimer in patients with clinically suspected pulmonary embolism
Chest
Measurement of D-dimer in plasma as diagnostic aid in suspected pulmonary embolism
Lancet
D-dimer correlates with proinflammatory cytokine levels and outcomes in critically ill patients
Chest
Fever in the ICU
Chest
The influence of inadequate antimicrobial treatment of bloodstream infections on patient outcomes in the ICU setting
Chest
Phlebotomy for diagnostic laboratory tests in adults. Pattern of use and effect on transfusion requirements
N Engl J Med
Evaluating laboratory usage in the intensive care unit: patient and institutional characteristics that influence frequency of blood sampling
Crit Care Med
Physician-attributable differences in intensive care unit costs: a single-center study
Am J Respir Crit Care Med
Effects of price information on test ordering in an intensive care unit
Intensive Care Med
Analysis of cost-effectiveness in intensive care: an overview of methods and review of applications to problems in critical care
Curr Opin Anaesthesiol
[Treatment costs in a medical intensive care unit: a comparison of 1992 and 1997]
Dtsch Med Wochenschr
Laboratory costs in the context of disease
Clin Chem
The trauma panel: laboratory test utilization in the initial evaluation of trauma patients
Emerg Med Rep
Critical care medicine in the United States 1985-2000: an analysis of bed numbers, use, and costs
Crit Care Med
Third Report of the National Cholesterol Education Program (NCEP) Expert Panel on Detection, Evaluation, and Treatment of High Blood Cholesterol in Adults (Adult Treatment Panel III) final report
Circulation
APACHE II: a severity of disease classification system
Crit Care Med
Outcome prediction for individual intensive care patients: useful, misused, or abused?
Intensive Care Med
Learning to not know: results of a program for ancillary cost reduction in surgical critical care
J Trauma
A utilization management intervention to reduce unnecessary testing in the coronary care unit
Arch Intern Med
Eliminating needless testing in intensive care—an information-based team management approach
Crit Care Med
The impact of peer management on test-ordering behavior
Ann Intern Med
Practice guideline for arterial blood gas measurement in the intensive care unit decreases numbers and increases appropriateness of tests
Crit Care Med
Analysis of laboratory critical value reporting at a large academic medical center
Am J Clin Pathol
American College of Chest Physicians/Society of Critical Care Medicine Consensus Conference: definitions for sepsis and organ failure and guidelines for the use of innovative therapies in sepsis
Crit Care Med
Surviving Sepsis Campaign guidelines for management of severe sepsis and septic shock
Crit Care Med
Early goal-directed therapy in the treatment of severe sepsis and septic shock
N Engl J Med
Best practice in therapeutic drug monitoring
Br J Clin Pharmacol
Mistakes in a stat laboratory: types and frequency
Clin Chem
Guidelines for meta-analyses evaluating diagnostic tests
Ann Intern Med
Biochemical profiles. Applications in ambulatory screening and preadmission testing of adults
Ann Intern Med
The CRIT Study: anemia and blood transfusion in the critically ill—current clinical practice in the United States
Crit Care Med
Important role of nondiagnostic blood loss and blunted erythropoietic response in the anemia of medical intensive care patients
Crit Care Med
Complications of critical care: lab testing and iatrogenic anemia
MLO Med Lab Obs
Anemia and blood transfusion in critically ill patients
JAMA
Cited by (0)
This article was supported by NIH/NHLBI grant K23 HL075076 (to J.M. O'Brien).