OBJECTIVE: An abnormality of the optical transmission waveform obtained during measurement of the activated partial thromboplastin time (aPTT) has been described in association with overt disseminated intravascular coagulation. This abnormality, a biphasic waveform, is caused by the in vitro formation of Ca2+-induced complexes between very low density lipoprotein and C-reactive protein. We have evaluated the diagnostic utility of aPTT waveform analysis for identifying patients with overt disseminated intravascular coagulation and sepsis.
DESIGN: Observational study investigating the predictive value of biphasic waveform for the diagnosis of sepsis and overt disseminated intravascular coagulation.
SETTING: Surgical intensive care unit of a university hospital.
SUBJECTS: We studied 331 consecutive patients admitted to the intensive care unit during a period of 6 months.
INTERVENTIONS: Laboratory analyses, including prothrombin time, aPTT, aPTT waveform analysis, fibrinogen, D-dimer antigen, and platelet count.
MEASUREMENTS AND MAIN RESULTS: At the most sensitive threshold value of the waveform variable for detection of the biphasic waveform (slope_1 = -0.05 %T/sec), this abnormality was detected in 54 of 331 patients (16.3%) at admission and 95 of 331 patients (28.7%) during the entire course of intensive care unit treatment. At this threshold, 59.3% of patients with a biphasic waveform on admission and 45.3% with a biphasic waveform during the total intensive care unit course were diagnosed with sepsis. Depending on the threshold value of slope_1, the sensitivity of aPTT waveform analysis for detection of sepsis varied between 22% and 55% at admission and between 48% and 74% during the entire intensive care unit stay. The specificity for sepsis varied between 92% and 98% and between 81% and 94%, for admission and total intensive care unit course, respectively. Biphasic waveform showed a comparable specificity for the diagnosis of overt disseminated intravascular coagulation, albeit at a lower sensitivity.
CONCLUSIONS: As an adjunct to routine coagulation testing in intensive care unit patients, aPTT waveform analysis is an elegant means for the rapid and highly specific identification of patients with sepsis.
