PSP Exam 2 chp. 11

Preanalytical Variables

Variables that occur before the analysis of a specimen, affecting test results.

Analytic Variables

Variables that occur during the analysis phase of laboratory testing.

Postanalytical Variables

Variables that occur after the analysis of a specimen, impacting result interpretation.

Syncope

A temporary loss of consciousness caused by a fall in blood pressure, often linked to fainting.

Hematoma

A localized collection of blood outside blood vessels, often due to a puncture or injury.

Hemolysis

The destruction of red blood cells, resulting in the release of hemoglobin into the plasma.

Compartment Syndrome

A condition where pressure within tissue prevents adequate blood flow, leading to tissue damage.

Intravenous (IV) Lines

Medical devices placed in a vein to

Patient Pre-analytical Variables

Conditions like fasting status, hydration, stress, recent exercise, medication, and time of day that can affect test results

Factors affecting Venipuncture Access

Physical limitations, presence of IV lines, burns, scars, mastectomy, edema, obesity, and uncooperative patient behavior.

Factors Affecting Patient Communication

Language barriers, hearing impairment, altered mental status, high anxiety levels, significant pain, and age.

Common Complications During Blood Collection

Syncope, hematoma, hemolysis, nerve damage, petechiae, excessive bleeding, and infection.

Factors Affecting Sample Integrity

Hemolysis, lipemia, icterus, incorrect anticoagulant use, insufficient volume (QNS), delayed processing, and improper temperature during transport/storage

Causes of Hemolysis During Collection

Vigorous mixing of tubes, using a needle with too small a gauge, aspirating blood too quickly, prolonged tourniquet application, incorrect venipuncture site, and vigorous shaking or rough handling of the tube.

Tests Significantly Affected by Hemolysis

Potassium (K), Lactate Dehydrogenase (LDH), Aspartate Aminotransferase (AST), complete blood count (CBC) parameters, and bilirubin levels. These tests can yield falsely elevated results due to the release of intracellular contents from lysed red blood cells.

Tests Affected by Patient Position

Albumin, enzymes, calcium, total protein, cholesterol, blood pressure, and certain drug levels (e.g., digoxin) can vary with changes in patient posture

Long-Term Complications of Venipuncture

Persistent nerve damage, arterial puncture with complications, chronic infection, phlebitis (vein inflammation), and thrombosis (blood clot formation).

Reasons for Specimen Rejection/Recollection

Hemolysis, clotted samples (when anticoagulated blood is required), incorrect tube type, quantity not sufficient (QNS), mislabeling or unlabeled specimens, and contamination.

Clinical Laboratory Testing Process

Involves physician order, specimen collection, transport, processing, analysis, result reporting, and clinical interpretation.