Activated partial thyomboplastin time waveform analysis:: A new tool to detect infection?

Objective: An abnormality of the optical transmission waveform obtained during measurement of the activated partial thromboplastin time (aPTT) has been described to identify a high-risk intensive care unit population consisting of patients with sepsis or with higher mortality rates than patients with normal aPTT waveforms. We investigated the abnormal aPTT biphasic waveform as a diagnostic and prognostic marker of infection. Design: Prospective, observational study investigating the predictive value of aPTT waveform analysis for the diagnosis and prognosis of sepsis. Setting. Surgical intensive care unit of a university hospital. Patients. We studied 187 consecutive patients who fulfilled at least two or more criteria of the systemic inflammatory response syndrome at admission or during intensive care stay and classified as having systemic inflammatory response syndrome, sepsis, severe sepsis, or septic shock during an 8-month period. Interventions. Laboratory analyses including aPTT waveform analysis and procalcitonin and C-reactive protein concentrations were measured at days 1-3. Measurements and Main Results: The final diagnoses were systemic inflammatory response syndrome in 49%, sepsis in 16%, severe sepsis in 12%, and septic shock in 23% of patients. On day 1, the biphasic waveform was significantly more abnormal in patients with severe sepsis or septic shock than in patients with systemic inflammatory response syndrome or sepsis. The biphasic waveform was more accurate than procalcitonin and C-reactive protein for differentiating patients with severe sepsis and septic shock, with 90% sensitivity and 92% negative predictive value. Biphasic waveform values were significantly more abnormal during days 1-3 in septic nonsurvivors than in survivors and nonseptic nonsurvivors. The biphasic waveform exhibited the best specificity (91%) and negative predictive value (98%) for the prognosis of sepsis-related mortality on day 3. Conclusions. In intensive care units, when the analyzer is available, aPTT waveform analysis is an inexpensive, rapid, effective, and readily available tool providing information for the diagnosis of severe sepsis and the prognosis of septic patients.