Logistic early warning scores to predict death, cardiac arrest or unplanned intensive care unit re-admission after cardiac surgery.

NHS England recently mandated that the National Early Warning Score of vital signs be used in all acute hospital trusts in the UK despite limited validation in the postoperative setting. We undertook a multicentre UK study of 13,631 patients discharged from intensive care after risk-stratified cardiac surgery in four centres, all of which used VitalPACTM to electronically collect postoperative National Early Warning Score vital signs. We analysed 540,127 sets of vital signs to generate a logistic score, the discrimination of which we compared with the national additive score for the composite outcome of: in-hospital death; cardiac arrest; or unplanned intensive care admission. There were 578 patients (4.2%) with an outcome that followed 4300 sets of observations (0.8%) in the preceding 24 h: 499 out of 578 (86%) patients had unplanned re-admissions to intensive care. Discrimination by the logistic score was significantly better than the additive score. Respective areas (95%CI) under the receiver-operating characteristic curve with 24-h and 6-h vital signs were: 0.779 (0.771-0.786) vs. 0.754 (0.746-0.761), p < 0.001; and 0.841 (0.829-0.853) vs. 0.813 (0.800-0.825), p < 0.001, respectively. Our proposed logistic Early Warning Score was better than the current National Early Warning Score at discriminating patients who had an event after cardiac surgery from those who did not.

Functional iron deficiency, infection and systemic inflammatory response syndrome in critical illness.

To investigate the prevalence and clinical relevance of functional iron deficiency in the critically ill, we performed a prospective observational study in a university hospital general intensive care unit. We collected patient demographics, severity of illness data, haematological and biochemical variables in 51 consecutive admissions. We recorded episodes of culture-positive infection. Functional iron deficiency (FID), measured by red cell hypochromasia on flow cytometry, was present in 35% of patients at admission to intensive care. FID patients were of similar age, diagnosis, APACHE score, sequential organ failure assessment (SOFA) score, haemoglobin, serum B12, folate and ferritin to patients without FID. However, patients with FID had a prolonged intensive care stay compared with non-FID patients (P<0.001) and increased time to hospital discharge (P=0.09). Duration of intensive care stay correlated with severity of FID (r=0.33, P<0.02). Systemic inflammatory response syndrome (SIRS) was present for longer in those with FID (P<0.02). Overall mortality did not differ between groups. No difference was seen in the incidence of positive cultures between those with FID (9/18 patients) and those without FID (15/33 patients). FID was independently associated only with abnormal white blood cell count (WBC < 4 or > 11 x 10(9) x l(-1)) at admission to ICU, P=0.007, but not with positive cultures. There is a high prevalence of FID in intensive care, associated with an increased duration of stay and duration of SIRS. We have been unable to demonstrate a link with infection, either as a predisposing factor or as an acute response.