Influence of posture on routine hemostasis testing.
Author(s): Lippi G, Salvagno GL, Lima-Oliveira G, Danese E, Favaloro EJ, Guidi GC
Publication: Blood Coagul Fibrinolysis, 2015, Vol. 26, Page 716-9
PubMed ID: 26083987 PubMed Review Paper? No
Purpose of Paper
The purpose of this paper was to determine the effects of patient posture (supine, sitting or standing) on clotting test results.
Conclusion of Paper
Changes in the patient’s posture (supine, sitting or standing) during blood collection statistically altered prothrombin time (PT), activated partial thromboplastin time (APTT), fibrinogen, hemoglobin, hematocrit levels and plasma volume. However, clinically relevant differences were limited to fibrinogen levels between supine and sitting or standing, and PT between supine and standing.
Studies
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Study Purpose
The purpose of this study was to determine the effects of patient posture (supine, sitting or standing) on clotting test results. Venous blood was acquired, without a tourniquet, from 19 healthy fasting patients after 25 minutes in a supine position, after 20 min of sitting, and again after 20 min of standing within a 0.5 m area. Blood was collected in K2EDTA (hemoglobin, and hematocrit) and sodium citrate (coagulation testing) tubes for each patient posture tested.
Summary of Findings:
The plasma volume from specimens obtained while the patient was sitting or standing were 3.4% and 14.1% lower, respectively, than those obtained while the patient was supine. Further, when the patient went from supine to sitting position the PT decreased (11.9 versus 11.7 s, p<0.001), fibrinogen increased (2.20 versus 2.27 g/L, p=0.001), hemoglobin increased (131 versus 134 g/L, p<0.001), and hematocrit increased (0.41 versus 0.42, p=0.009), but APTT remained comparable. Similarly, specimens obtained after standing for 20 min had elevated fibrinogen (2.20 versus 2.41 g/L), prolonged APTT (30.9 s versus 31.6 s, p<0.001), and significant decreases in PT (11.9 s versus 11.4 s, p<0.001), hemoglobin (131 versus 141 g/L, p<0.001) and hematocrit (0.41 versus 0.44, p<0.001) compared to specimens obtained after the patient was supine for 25 min. Importantly, the biases in fibrinogen between supine and sitting or standing, and in PT between supine and standing were considered clinically significant.
Biospecimens
Preservative Types
- None (Fresh)
Diagnoses:
- Normal
Platform:
Analyte Technology Platform Glycoprotein Hematology/ auto analyzer Protein Spectrophotometry Cell count/volume Hematology/ auto analyzer Morphology Hematology/ auto analyzer Pre-analytical Factors:
Classification Pre-analytical Factor Value(s) Biospecimen Acquisition Patient posture Sitting
Standing
Supine