Prognostic value of shock index in children with septic shock.

OBJECTIVES: Septic shock is frequent in children and is associated with high mortality and morbidity rates. Early recognition of severe sepsis improve outcome. Shock index (SI), ratio of heart rate (HR) and systolic blood pressure (SBP), may be a good noninvasive measure of hemodynamic instability that has been poorly studied in children. The aim of the study was to explore the usefulness of SI as an early index of prognosis for septic shock in children. METHODS: The study was retrospective and performed in 1 pediatric intensive care unit at a university hospital. The following specific data were collected at 0, 1, 2, 4, and 6 hours after admission: HR and SBP for SI calculation and lactate concentration. Patients were divided into 2 groups according to their outcome (death/survival). RESULTS: A total of 146 children admitted with septic shock between January 2000 and April 2010 were included. Shock index was significantly different between survivors and nonsurvivors at 0, 4, and 6 hours after admission (P = 0.02, P = 0.03, and P = 0.008, respectively). Age-adjusted SIs were different between survivors and nonsurvivors at 0 and 6 hours, with a relative risk of death at these time points of 1.85 (1.04-3.26) (P = 0.03) and 2.17 (1.18-3.96) (P = 0.01), respectively. Moreover, an abnormal SI both at admission and at 6 hours was predictive of death with relative risk of 1.36 (1.05-1.76). CONCLUSIONS: In our population of children with septic shock, SI was a clinically relevant and easily calculated predictor of mortality. It could be a better measure of hemodynamic status than HR and SBP alone, allowing for the early recognition of severe sepsis.

Assessment of the Pediatric Index of Mortality 2 with the Pao2/Fio2 ratio derived from the Spo2/Fio2 ratio: a prospective pilot study in a French pediatric intensive care unit.

OBJECTIVE: The Pediatric Index of Mortality 2 is a mortality prediction tool used in pediatric intensive care units. Arterial blood gas sampling that is required to calculate the Pao2/Fio2 ratio is often unavailable. Several authors have proposed mathematical relations between the Pao2/Fio2 and Spo2/Fio2 ratios. The main objective of this study was to assess the validity of the Pediatric Index of Mortality 2 score and three modified Pediatric Index of Mortality 2 scores with the Pao2/Fio2 ratio calculated from the Spo2/Fio2 ratio. DESIGN: Prospective observational study of consecutive patients admitted during a 23-month period. SETTING: A multidisciplinary French pediatric intensive care unit. PATIENTS: One thousand forty-three patients, 80 of whom died (7.7%). INTERVENTIONS: None. MEASUREMENTS AND MAINS RESULTS: Only 15 of 1043 patients had a Pao2 measurement. Spo2/Fio2 ratio was determined for 338 patients (33%) for whom Fio2 was known and Spo2 was ≤ 97%. However, for mathematical reasons, Pao2/FIo2 ratio could be calculated from the three Spo2/Fio2 equations for 328 (31%), 295 (28%), and 100 (10%) patients, respectively. Discrimination assessed by the area under the receiver operating characteristic curve was 0.86 for Pediatric Index of Mortality 2 and the modified scores. Calibration assessed by the Hosmer-Lemeshow goodness-of-fit test was poor for Pediatric Index of Mortality 2 (p = .04) and one modified score (p = .03) and good for two other modified scores (p = .06, p = .09). CONCLUSION: This study suggests that the Spo2/Fio2 ratio could be used in place of Pao2/Fio2 for calculating Pediatric Index of Mortality 2. This must nonetheless be confirmed by a larger prospective multicenter study.

Does taking endurance into account improve the prediction of weaning outcome in mechanically ventilated children?

INTRODUCTION: We conducted the present study to determine whether a combination of the mechanical ventilation weaning predictors proposed by the collective Task Force of the American College of Chest Physicians (TF) and weaning endurance indices enhance prediction of weaning success. METHOD: Conducted in a tertiary paediatric intensive care unit at a university hospital, this prospective study included 54 children receiving mechanical ventilation (> or = 6 hours) who underwent 57 episodes of weaning. We calculated the indices proposed by the TF (spontaneous respiratory rate, paediatric rapid shallow breathing, rapid shallow breathing occlusion pressure [ROP] and maximal inspiratory pressure during an occlusion test [Pimax]) and weaning endurance indices (pressure-time index, tension-time index obtained from P(0.1) [TTI1] and from airway pressure [TTI2]) during spontaneous breathing. Performances of each TF index and combinations of them were calculated, and the best single index and combination were identified. Weaning endurance parameters (TTI1 and TTI2) were calculated and the best index was determined using a logistic regression model. Regression coefficients were estimated using the maximum likelihood ratio (LR) method. Hosmer-Lemeshow test was used to estimate goodness-of-fit of the model. An equation was constructed to predict weaning success. Finally, we calculated the performances of combinations of best TF indices and best endurance index. RESULTS: The best single TF index was ROP, the best TF combination was represented by the expression (0.66 x ROP) + (0.34 x Pimax), and the best endurance index was the TTI2, although their performance was poor. The best model resulting from the combination of these indices was defined by the following expression: (0.6 x ROP) - (0.1 x Pimax) + (0.5 x TTI2). This integrated index was a good weaning predictor (P < 0.01), with a LR+ of 6.4 and LR+/LR- ratio of 12.5. However, at a threshold value < 1.3 it was only predictive of weaning success (LR- = 0.5). CONCLUSION: The proposed combined index, incorporating endurance, was of modest value in predicting weaning outcome. This is the first report of the value of endurance parameters in predicting weaning success in children. Currently, clinical judgement associated with spontaneous breathing trials apparently remain superior.