although our understanding of the pathophysiology of sepsis and of subsequently derived therapeutic approaches has advanced significantly in the past , mortality of sepsis still remains unacceptably high . to improve this dilemma , diagnostic laboratory tests are urgently required that possess a high degree of accuracy and for which the results can be obtained in a very short time . for patients after cardiopulmonary bypass surgery , a recent publication demonstrated that an activated partial thromboplastin time biphasic waveform ( bpw ) analysis was able to discriminate between sepsis and nonseptic systemic inflammatory response syndrome ( sirs ) with a sensitivity of 100% and a specificity of 93% . in all patients , the specificity and sensitivity of c - reactive protein ( crp ) and procalcitonin ( pct ) were inferior with respect to pneumonia prediction . delannoy and colleagues showed that perioperative complications such as haemorrhage , tamponade or reoperation were all associated with the emergence of postoperative sirs and sepsis . for cardiac surgical patients , those observations are in line with the commonly accepted hypothesis that a large tissue trauma or prolonged states of shock initially lead to an increased inflammatory response that is followed by a state of immunosuppression , thereby increasing the susceptibility to infectious complications . in these patients if an infectious focus becomes clinically evident , it will usually be too late to prevent the beginning of the septic vicious circle ( for example , by initiating specific therapies such as antibiotics or surgical interventions ) . physicians caring for patients in intensive care units ( icus ) usually have a thorough knowledge of common infectious and noninfectious mechanisms that may cause fever in their patients . many patients who are actually suffering from a septic focus , however , do not become febrile at the same time ( for example , elderly patients or patients with uraemia ) . in those septic patients , the absence of secondary fever or of a general acute - phase response can not be regarded as a favourable prognostic sign , but rather reflects the immunosuppressive phase of sepsis being associated with a high mortality . other early manifestations of sepsis include a minor increase or decrease in the white - cell count or neutrophil percentage , a subtle change of mental status , or an elevated blood glucose level . early recognition of a septic state and of the septic focus is essential for successful treatment . the time to diagnosis , however , is often prolonged because key indicators ( fever ) are either missing , or have low specificity and sensitivity ( leukocyte count ) , or can be only registered with a significant time delay ( results from microbiological cultures ) . because of these weaknesses , the availability of new biomarkers ( pct and il-6 ) raised high hopes for all those caring for septic patients . throughout the past years , the accuracy , predictive power and clinical utility of those biomarkers has been studied extensively . a meta - analysis of 33 studies concluded that pct constitutes an excellent laboratory marker for the discrimination between sirs and sepsis . when assessing the risk of patients with sirs to develop sepsis , these authors found a global odds ratio of 15.6 when pct concentrations were elevated , whereas the odds ratio was only 5.4 with increased crp levels . the optimal decisional cut - off point varied between 0.6 and 5 ng / l when pct was analysed , whereas corresponding variations were clearly wider for crp ( 39 to 180 mg / l ) . a similar superiority with respect to postoperative risk prediction was also found exclusively in surgical patients , where the accuracy of pct even surmounted that of il-6 . in selected patient populations , however , including immunosuppressed or very old patients , the diagnostic performance of pct seems to vary . in our own patient population , we made similar observations . some patients had a normal pct concentration after solid organ transplantation , although there was unequivocal evidence for a serious infection . this disease - specific pct reaction may be one of the reasons for the inconclusive results from another systematic review published recently . it should be noted that the use of crp as a diagnostic tool is not completely unhelpful . studies focusing selectively on crp attested acceptable reliability , with a sensitivity of 85% and a specificity of about 70% . downey and colleagues were the first to discover an abnormality of the optical transmission waveform obtained during measurement of the activated partial thromboplastin time ( reviewed in ) . this abnormality , a bpw , is caused by in vitro formation of calcium - induced complexes between very - low - density lipo proteins and crp . waveform analysis is a rapid and inexpensive method , being part of the routine activated partial thromboplastin time measurement . subsequent studies identified bpw analysis as an indicator of a systemic inflammatory response , as observed in sepsis . the present study by delannoy and colleagues demonstrated that bpw analysis was able to discriminate between sepsis and non septic sirs patients with a sensitivity of 100% and a specificity of 93% ( threshold value of 0.456%t / second ) . only 32 cardiac surgery patients , however , were included . an earlier investigation by chopin and colleagues studied 187 patients with 217 episodes of sirs , of which 34 patients were classified with sepsis , 26 patients with severe sepsis , and 50 patients with septic shock . the diagnostic sensitivity and specificity of bpw analysis for the combined group of severe sepsis and septic shock were 92% and 67% , respectively . in another recent study in icu patients , the sensitivity of bpw analysis for sepsis was 81% , with a specificity of 76% . the combination of bpw analysis with pct measurement did not increase the sensitivity but raised the specificity to 94% . smith and colleagues found that non - icu patients are more likely to have positive blood cultures when waveform analysis yields abnormal results . bpw analysis therefore appears to be a promising parameter for the discrimination between sirs and sepsis . to corroborate the use of bpw analysis , only if the precise diagnostic significance is established in relation to the underlying disease will bpw analysis become an important component in the routine panel of sepsis markers currently used . bpw : biphasic waveform ; crp : c - reactive protein ; icu : intensive care unit ; il : interleukin ; pct : procalcitonin ; sirs : systemic inflammatory response syndrome .
throughout the last years , several new diagnostic biomarkers have been introduced into clinical routine to identify a systemic inflammatory response syndrome ( sirs ) or a septic state and to discriminate between these two entities . 
 according to studies in selected patients , measurement of these biomarkers may be advantageous under certain clinical conditions . on an individual basis , however , these sepsis markers usually lack an adequate negative or positive predictive power . 
 therefore , physicians in charge still have to rely on a combination of personal experience and results from clinical or laboratory tests when deciding on a patient 's therapy . for surgical patients , a key problem consists of the time delay which is associated with the diagnosis of serious postoperative infections and which may negatively affect outcome . 
 it is in this context where the activated partial thromboplastin time waveform analysis may represent a promising new method to discriminate between sirs and sepsis , thereby shortening the time to therapy . 
 nevertheless , studies involving large patient populations will be necessary to prove the efficacy of this new diagnostic concept either as a single tool or in combination with the measurement of other biomarkers .