The Inadequate Oxygen Delivery Index and Low Cardiac Output Syndrome Score As Predictors of Adverse Events Associated With Low Cardiac Output Syndrome Early After Cardiac Bypass.

OBJECTIVES: To evaluate the effectiveness of two scoring systems, the inadequate oxygen delivery index, a risk analytics algorithm (Etiometry, Boston, MA) and the Low Cardiac Output Syndrome Score, in predicting adverse events recognized as indicative of low cardiac output syndrome within 72 hours of surgery. DESIGN: A retrospective observational pair-matched study. SETTING: Tertiary pediatric cardiac ICU. PATIENTS: Children undergoing cardiac bypass for congenital heart defects. Cases experienced an adverse event linked to low cardiac output syndrome in the 72 hours following surgery (extracorporeal membrane oxygenation, renal replacement therapy, cardiopulmonary resuscitation, and necrotizing enterocolitis) and were matched with a control patient on criteria of procedure, diagnosis, and age who experienced no such event. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Of a total 536 bypass operations in the study period, 38 patients experienced one of the defined events. Twenty-eight cases were included in the study after removing patients who suffered an event after 72 hours or who had insufficient data. Clinical and laboratory data were collected to derive scores for the first 12 hours after surgery. The inadequate oxygen delivery index was calculated by Etiometry using vital signs and laboratory data. A modified Low Cardiac Output Syndrome Score was calculated from clinical and therapeutic markers. The mean inadequate oxygen delivery and modified Low Cardiac Output Syndrome Score were compared within each matched pair using the Wilcoxon signed-rank test. Inadequate oxygen delivery correctly differentiated adverse events in 13 of 28 matched pairs, with no evidence of inadequate oxygen delivery being higher in cases (p = 0.71). Modified Low Cardiac Output Syndrome Score correctly differentiated adverse events in 23 of 28 matched pairs, with strong evidence of a raised score in low cardiac output syndrome cases (p < 0.01). CONCLUSIONS: Although inadequate oxygen delivery is an Food and Drug Administration approved indicator of risk for low mixed venous oxygen saturation, early postoperative average values were not linked with medium-term adverse events. The indicators included in the modified Low Cardiac Output Syndrome Score had a much stronger association with the specified adverse events.

Interventional treatments and risk factors in patients born with hypoplastic left heart syndrome in England and Wales from 2000 to 2015.

OBJECTIVE: To describe the long-term outcomes, treatment pathways and risk factors for patients diagnosed with hypoplastic left heart syndrome (HLHS) in England and Wales. METHODS: The UK's national audit database captures every procedure undertaken for congenital heart disease and updated life status for resident patients in England and Wales. Patients with HLHS born between 2000 and 2015 were identified using codes from the International Paediatric and Congenital Cardiac Code. RESULTS: There were 976 patients with HLHS. Of these, 9.6% had a prepathway intervention, 89.5% underwent a traditional pathway of staged palliation and 6.4% of infants underwent a hybrid pathway. Patients undergoing prepathway procedures or the hybrid pathway were more complex, exhibiting higher rates of prematurity and acquired comorbidity. Prepathway intervention was associated with the highest in-hospital mortality (34.0%).44.6% of patients had an off-pathway procedure after their primary procedure, most frequently stenting or dilation of residual or recoarctation and most commonly occurring between stage 1 and stage 2.The survival rate at 1 year and 5 years was 60.7% (95% CI 57.5 to 63.7) and 56.3% (95% CI 53.0 to 59.5), respectively. Patients with an antenatal diagnosis (multivariable HR (MHR) 1.63 (95% CI 1.12 to 2.38)), low weight (<2.5 kg) (MHR 1.49 (95% CI 1.05 to 2.11)) or the presence of an acquired comorbidity (MHR 2.04 (95% CI 1.30 to 3.19)) were less likely to survive. CONCLUSION: Treatment pathways among patients with HLHS are complex and variable. It is essential that the long-term outcomes of conditions like HLHS that require serial interventions are studied to provide a fuller picture and to inform quality assurance and improvement.

The Effect of Acetaminophen on Temperature in Critically Ill Children: A Retrospective Analysis of Over 50,000 Doses.

OBJECTIVES: Acetaminophen is widely used in PICUs. Although randomized controlled trials suggest that acetaminophen significantly reduces body temperature in adults, the effect of acetaminophen on temperature in critically ill children has not been previously quantified. DESIGN: Retrospective observational cohort study. SETTING: Single-center general and cardiac PICU in a specialist children's hospital. PATIENTS: All children who received acetaminophen or had a fever (temperature ≥ 38°C) while on the ICU over a 40-month period (September 2012 to December 2015). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: In total, 58,177 doses of acetaminophen were administered, with temperature data available for analysis for 54,084 doses. Temperature decreased by 0.11°C (95% CI, 0.09-0.14°C) 4 hours post acetaminophen dose, after adjustment for weight and illness severity. In children who had a fever and were given acetaminophen, temperature decreased by 0.78°C (95% CI, 0.74-0.82°C). Temperature decreased by 0.88°C (95% CI, 0.85-0.92°C) in children who had fever but did not receive acetaminophen. The change in temperature associated with fever was significantly different between those who did and did not receive acetaminophen (likelihood ratio statistic 246.06; p < 2.2 × 10(-16)). CONCLUSIONS: Acetaminophen is associated with a significant decrease in temperature in children with fever. However, temperature may decrease following fever without acetaminophen in the PICU. The threshold to use acetaminophen must be understood to determine the true effect on temperature in any future trials.

Improving Risk Adjustment for Mortality After Pediatric Cardiac Surgery: The UK PRAiS2 Model.

BACKGROUND: Partial Risk Adjustment in Surgery (PRAiS), a risk model for 30-day mortality after children's heart surgery, has been used by the UK National Congenital Heart Disease Audit to report expected risk-adjusted survival since 2013. This study aimed to improve the model by incorporating additional comorbidity and diagnostic information. METHODS: The model development dataset was all procedures performed between 2009 and 2014 in all UK and Ireland congenital cardiac centers. The outcome measure was death within each 30-day surgical episode. Model development followed an iterative process of clinical discussion and development and assessment of models using logistic regression under 25 × 5 cross-validation. Performance was measured using Akaike information criterion, the area under the receiver-operating characteristic curve (AUC), and calibration. The final model was assessed in an external 2014 to 2015 validation dataset. RESULTS: The development dataset comprised 21,838 30-day surgical episodes, with 539 deaths (mortality, 2.5%). The validation dataset comprised 4,207 episodes, with 97 deaths (mortality, 2.3%). The updated risk model included 15 procedural, 11 diagnostic, and 4 comorbidity groupings, and nonlinear functions of age and weight. Performance under cross-validation was: median AUC of 0.83 (range, 0.82 to 0.83), median calibration slope and intercept of 0.92 (range, 0.64 to 1.25) and -0.23 (range, -1.08 to 0.85) respectively. In the validation dataset, the AUC was 0.86 (95% confidence interval [CI], 0.82 to 0.89), and the calibration slope and intercept were 1.01 (95% CI, 0.83 to 1.18) and 0.11 (95% CI, -0.45 to 0.67), respectively, showing excellent performance. CONCLUSIONS: A more sophisticated PRAiS2 risk model for UK use was developed with additional comorbidity and diagnostic information, alongside age and weight as nonlinear variables.

Incorporating Comorbidity Within Risk Adjustment for UK Pediatric Cardiac Surgery.

BACKGROUND: When considering early survival rates after pediatric cardiac surgery it is essential to adjust for risk linked to case complexity. An important but previously less well understood component of case mix complexity is comorbidity. METHODS: The National Congenital Heart Disease Audit data representing all pediatric cardiac surgery procedures undertaken in the United Kingdom and Ireland between 2009 and 2014 was used to develop and test groupings for comorbidity and additional non-procedure-based risk factors within a risk adjustment model for 30-day mortality. A mixture of expert consensus based opinion and empiric statistical analyses were used to define and test the new comorbidity groups. RESULTS: The study dataset consisted of 21,838 pediatric cardiac surgical procedure episodes in 18,834 patients with 539 deaths (raw 30-day mortality rate, 2.5%). In addition to surgical procedure type, primary cardiac diagnosis, univentricular status, age, weight, procedure type (bypass, nonbypass, or hybrid), and era, the new risk factor groups of non-Down congenital anomalies, acquired comorbidities, increased severity of illness indicators (eg, preoperative mechanical ventilation or circulatory support) and additional cardiac risk factors (eg, heart muscle conditions and raised pulmonary arterial pressure) all independently increased the risk of operative mortality. CONCLUSIONS: In an era of low mortality rates across a wide range of operations, non-procedure-based risk factors form a vital element of risk adjustment and their presence leads to wide variations in the predicted risk of a given operation.

PaO2/FIO2 Ratio Derived From the SpO2/FIO2 Ratio to Improve Mortality Prediction Using the Pediatric Index of Mortality-3 Score in Transported Intensive Care Admissions.

OBJECTIVES: To derive a relationship between the SpO2/FIO2 ratio and PaO2/FIO2 ratio across the entire range of SpO2 values (0-100%) and to evaluate whether mortality prediction using the Pediatric Index of Mortality-3 can be improved by the use of PaO2/FIO2 values derived from SpO2/FIO2. DESIGN: Retrospective analysis of prospectively collected data. SETTING: A regional PICU transport service. PATIENTS: Children transported to a PICU. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The relationship between SpO2/FIO2 and PaO2/FIO2 across the entire range of SpO2 values was first studied using several mathematical models in a derivation cohort (n = 1,235) and then validated in a separate cohort (n = 306). The best SpO2/FIO2-PaO2/FIO2 relationship was chosen according to the ability to detect respiratory failure (PaO2/FIO2 ≤ 200). The discrimination of the original Pediatric Index of Mortality-3 score and a derived Pediatric Index of Mortality-3 score (where SpO2/FIO2-derived PaO2/FIO2 values were used in place of missing PaO2/FIO2 values) were compared in a different cohort (n = 1,205). The best SpO2/FIO2-PaO2/FIO2 relationship in 1,703 SpO2/FIO2-to-PaO2/FIO2 data pairs was a linear regression equation of ln[PF] regressed on ln[SF]. This equation identified children with a PaO2/FIO2 less than or equal to 200 with a specificity of 73% and sensitivity of 61% in children with SpO2 less than 97% (92% and 33%, respectively, when SpO2 ≥ 97%) in the validation cohort. PaO2/FIO2 derived from SpO2/FIO2 (derived PaO2/FIO2) was better at predicting PICU mortality (area under receiver operating characteristic curve, 0.64; 95% CI, 0.55-0.73) compared with the original PaO2/FIO2 (area under receiver operating characteristic curve, 0.54; 95% CI, 0.49-0.59; p = 0.02). However, there was no difference in the original and derived Pediatric Index of Mortality-3 scores and their discriminatory ability for mortality. CONCLUSIONS: SpO2-based metrics perform no worse than arterial blood gas-based metrics in mortality prediction models. Future Pediatric Index of Mortality score versions may be improved by the inclusion of risk factors based on oxygen saturation values, especially in settings where PaO2 values are missing in a significant proportion of cases.