Elsevier

Critical Care Clinics

Volume 23, Issue 3, July 2007, Pages 435-465
Critical Care Clinics

Laboratory Testing in the Intensive Care Unit

https://doi.org/10.1016/j.ccc.2007.07.005Get rights and content

Laboratory testing is ubiquitous among hospitalized patients and is more common among patients in the intensive care unit (ICU). Despite its high cost and prevalence, there are few data to support the current practice of laboratory testing in most ICUs. Although testing offers considerable potential benefits, it is not without risk, including misleading results, iatrogenic anemia, and therapeutic actions of uncertain benefit. Laboratory testing should be conducted as part of a therapeutic approach to a clinical problem, mindful of pretest probability of disease, the performance of the selected test, and the relative benefits and risks of testing. Considering the indication for a particular test can lead to a more rational approach to laboratory testing and better use of available tests.

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)

  • P. Ammann et al.

    Troponin as a risk factor for mortality in critically ill patients without acute coronary syndromes

    J Am Coll Cardiol

    (2003)
  • P.R. Forfia et al.

    Relationship between B-type natriuretic peptides and pulmonary capillary wedge pressure in the intensive care unit

    J Am Coll Cardiol

    (2005)
  • D. Jefic et al.

    Utility of B-type natriuretic peptide and N-terminal pro B-type natriuretic peptide in evaluation of respiratory failure in critically ill patients

    Chest

    (2005)
  • H. Dokainish et al.

    Comparative accuracy of B-type natriuretic peptide and tissue Doppler echocardiography in the diagnosis of congestive heart failure

    Am J Cardiol

    (2004)
  • P. Raimondi et al.

    D-dimer plasma concentration in various clinical conditions: implication for the use of this test in the diagnostic approach of venous thromboembolism

    Thromb Res

    (1993)
  • J.S. Ginsberg et al.

    D-dimer in patients with clinically suspected pulmonary embolism

    Chest

    (1993)
  • H. Bounameaux et al.

    Measurement of D-dimer in plasma as diagnostic aid in suspected pulmonary embolism

    Lancet

    (1991)
  • A.F. Shorr et al.

    D-dimer correlates with proinflammatory cytokine levels and outcomes in critically ill patients

    Chest

    (2002)
  • P.E. Marik

    Fever in the ICU

    Chest

    (2000)
  • E.H. Ibrahim et al.

    The influence of inadequate antimicrobial treatment of bloodstream infections on patient outcomes in the ICU setting

    Chest

    (2000)
  • B.R. Smoller et al.

    Phlebotomy for diagnostic laboratory tests in adults. Pattern of use and effect on transfusion requirements

    N Engl J Med

    (1986)
  • J.E. Zimmerman et al.

    Evaluating laboratory usage in the intensive care unit: patient and institutional characteristics that influence frequency of blood sampling

    Crit Care Med

    (1997)
  • A. Garland et al.

    Physician-attributable differences in intensive care unit costs: a single-center study

    Am J Respir Crit Care Med

    (2006)
  • P. Seguin et al.

    Effects of price information on test ordering in an intensive care unit

    Intensive Care Med

    (2002)
  • D.B. Chalfin

    Analysis of cost-effectiveness in intensive care: an overview of methods and review of applications to problems in critical care

    Curr Opin Anaesthesiol

    (1996)
  • H. Klepzig et al.

    [Treatment costs in a medical intensive care unit: a comparison of 1992 and 1997]

    Dtsch Med Wochenschr

    (1998)
  • D.S. Young et al.

    Laboratory costs in the context of disease

    Clin Chem

    (2000)
  • A. Asimos

    The trauma panel: laboratory test utilization in the initial evaluation of trauma patients

    Emerg Med Rep

    (1997)
  • N.A. Halpern et al.

    Critical care medicine in the United States 1985-2000: an analysis of bed numbers, use, and costs

    Crit Care Med

    (2004)
  • National Center for Health Statistics. National Health and Nutrition Examination Survey (NHANES). Centers for Disease...
  • 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

    (2002)
  • W.A. Knaus et al.

    APACHE II: a severity of disease classification system

    Crit Care Med

    (1985)
  • S. Lemeshow et al.

    Outcome prediction for individual intensive care patients: useful, misused, or abused?

    Intensive Care Med

    (1995)
  • P.S. Barie et al.

    Learning to not know: results of a program for ancillary cost reduction in surgical critical care

    J Trauma

    (1996)
  • T.J. Wang et al.

    A utilization management intervention to reduce unnecessary testing in the coronary care unit

    Arch Intern Med

    (2002)
  • D.E. Roberts et al.

    Eliminating needless testing in intensive care—an information-based team management approach

    Crit Care Med

    (1993)
  • E.G. Neilson et al.

    The impact of peer management on test-ordering behavior

    Ann Intern Med

    (2004)
  • C.S. Pilon et al.

    Practice guideline for arterial blood gas measurement in the intensive care unit decreases numbers and increases appropriateness of tests

    Crit Care Med

    (1997)
  • A.S. Dighe et al.

    Analysis of laboratory critical value reporting at a large academic medical center

    Am J Clin Pathol

    (2006)
  • 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

    (1992)
  • R.P. Dellinger et al.

    Surviving Sepsis Campaign guidelines for management of severe sepsis and septic shock

    Crit Care Med

    (2004)
  • E. Rivers et al.

    Early goal-directed therapy in the treatment of severe sepsis and septic shock

    N Engl J Med

    (2001)
  • A.S. Gross

    Best practice in therapeutic drug monitoring

    Br J Clin Pharmacol

    (1998)
  • M. Plebani et al.

    Mistakes in a stat laboratory: types and frequency

    Clin Chem

    (1997)
  • L. Irwig et al.

    Guidelines for meta-analyses evaluating diagnostic tests

    Ann Intern Med

    (1994)
  • R.D. Cebul et al.

    Biochemical profiles. Applications in ambulatory screening and preadmission testing of adults

    Ann Intern Med

    (1987)
  • H.L. Corwin et al.

    The CRIT Study: anemia and blood transfusion in the critically ill—current clinical practice in the United States

    Crit Care Med

    (2004)
  • N. von Ahsen et al.

    Important role of nondiagnostic blood loss and blunted erythropoietic response in the anemia of medical intensive care patients

    Crit Care Med

    (1999)
  • S. Woodhouse

    Complications of critical care: lab testing and iatrogenic anemia

    MLO Med Lab Obs

    (2001)
  • J.L. Vincent et al.

    Anemia and blood transfusion in critically ill patients

    JAMA

    (2002)
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    This article was supported by NIH/NHLBI grant K23 HL075076 (to J.M. O'Brien).

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