Current challenges in cardiac intensive care: optimal strategies for mechanical ventilation and timing of extubation

Clinical Outcomes and Risk Factors for In-Hospital Mortality in Neonates with Hypoplastic Left Heart Syndrome

The objective of this study was to identify patient and hospitalization characteristics associated with in-hospital mortality in infants with hypoplastic left heart syndrome (HLHS). We conducted a retrospective analysis of a large administrative database, the National Inpatient Sample dataset of the Healthcare Cost and Utilization Project for the years 2002-2016. Neonates with HLHS were identified by ICD-9 and ICD-10 codes. Hospital and patient factors associated with inpatient mortality were analyzed. Overall, 18,867 neonates met the criteria of inclusion; a total of 3813 patients died during the hospitalization (20.2%). In-hospital mortality decreased over the years of the study (27.0% in 2002 vs. 18.3% in 2016). Extracorporeal membrane oxygenation utilization was 8.1%. Univariate and multivariate logistic regression analyses were used to identify risk factors for in-hospital mortality in infants with hypoplastic left heart syndrome. Independent non-modifiable risk factors for mortality were birth weight < 2500 g (Adjusted odds ratio (aOR) 2.16 [1.74-2.69]), gestational age < 37 weeks (aOR 1.73 [1.42-2.10]), chromosomal abnormalities (aOR 3.07 [2.60-3.64]) and renal anomalies (aOR 1.34 [1.10-1.61]). Independent modifiable risk factors for mortality were being transferred-in from another hospital (aOR 1.15 [1.03-1.29]), use of extracorporeal membrane oxygenation (aOR 12.74 [10.91-14.88]). Receiving care in a teaching hospital is a modifiable variable, and it decreased the odds of mortality (aOR 0. 78 [0.64-0.95]). In conclusion, chromosomal anomalies, Extra Corporeal Membrane Oxygenation, gestational age < 37 weeks or birth weight < 2500 g were associated with increased odds of mortality. Modifiable variables as receiving care at birth center and in a hospital designated as a teaching hospital decreased the odds of mortality.

Outcomes of hypoplastic left heart syndrome: analysis of National Inpatient Sample Database 1998-2004 versus 2005-2014

Neonates with hypoplastic left heart syndrome (HLHS) were identified from the National Inpatient Sample dataset for the years 1998-2014. These patients were stratified into two chronological groups, past group (1998-2005) and recent group (2006-2014). A total of 20,649 neonates with HLHS were identified. Of them, 9179 (44.5%) were born in the past group and 11,470 (55.5%) in the recent group. Median birth weight was significantly less in the recent group (2967 g vs. 3110 g, p = 0.005). The patients in the recent group had more patients with low birth weight ( < 2.5 kg) and prematurity (8.7% vs 7.6% and 12.7% vs. 4.3%., respectively). In addition, recent group had more comorbidities including chromosomal anomalies, total anomalous pulmonary venous return, and kidney anomalies (5.6% vs. 3.6%, 2.3% vs. 1.7%, and 5.6% vs. 3.6%, respectively, p < 0.001); these were associated with a higher rate of extracorporeal membrane oxygenation utilization (9.2% vs. 4.5%, p < 0.001). Consequently, median length of stay was longer in the recent group (8 vs. 6 days, p < 0.001).Conclusion: Despite the higher frequency of comorbidities in recent group, the mortality rates decreased by 20% (from 25.3% to 20.6%, p < 0.001). Balloon atrial septostomy was performed less frequently in the recent group (23.3% vs. 16.1%, p < 0.001).What is known:• Hypoplastic left heart syndrome has the highest mortality among congenital cardiac defects during the first year of life.• Limited studies on patients' comorbidities and mortality rates trends over last two decades.What is new:• The study utilized a national database to compare in-hospital mortality and length of stay between the two time periods 1998-2005 and 2006-2014.• The recent group had more comorbidities (prematurity, chromosomal anomalies, total anomalous pulmonary venous return, and kidney anomalies), and there was higher rate of ECMO and longer length of stay, while mortality rates decreased by 20%.

Extent, risk factors, and outcome of fluid overload after pediatric heart surgery*

OBJECTIVES

Fluid overload is associated with poor PICU outcomes in different populations. Little is known about fluid overload in children undergoing cardiac surgery. We described fluid overload after cardiac surgery, identified risk factors of worse fluid overload and also determined if fluid overload predicts longer length of PICU stay, prolonged mechanical ventilation (length of ventilation) and worse lung function as estimated by the oxygenation index.

DESIGN

Retrospective cohort study.

SETTING

Montreal Children's Hospital PICU, Montreal, Canada.

PATIENTS

Patients 18 years or younger undergoing cardiac surgery (2005-2007).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Cumulative fluid overload % was calculated as [(total fluid in - out in L)/admission weight (kg) × 100] and expressed as PICU peak cumulative fluid overload % throughout admission and PICU day 2 cumulative fluid overload %. Primary outcomes were length of stay and length of ventilation. The secondary outcome was oxygenation index. Fluid overload risk factors were evaluated using stepwise linear regression. Fluid overload-outcome relations were evaluated using stepwise Cox regression (length of stay, length of ventilation) and generalized estimating equations (daily PICU cumulative fluid overload % and oxygenation index repeated measures). There were 193 eligible surgeries. Peak cumulative fluid overload % was 7.4% ± 11.2%. Fluid overload peaked on PICU day 2. Lack of past cardiac surgery (p = 0.04), cyanotic heart disease (p = 0.03), and early postoperative fluids (p = 0.0001) was independently associated with higher day 2 fluid overload %. Day 2 fluid overload % predicted longer length of stay (adjusted hazard ratio, 0.95; 95% CI, 0.92-0.99; p = 0.009) and length of ventilation (adjusted hazard ratio, 0.97; 95% CI, 0.94-0.99; p = 0.03). In patients without cyanotic heart disease, worse daily fluid overload % predicted worse daily oxygenation index.

CONCLUSION

Fluid overload occurs early after cardiac surgery and is associated with prolonged PICU length of stay and ventilation. Future fluid overload avoidance trials may confirm or refute a true fluid overload-outcome causative association.

Noninvasive positive pressure ventilation in critically ill children with cardiac disease

Noninvasive ventilation is effective in respiratory failure from various etiologies. This study aimed to analyze the efficacy of noninvasive positive pressure ventilation (NPPV) in pediatric cardiac patients. NPPV was used (1) as an alternative means of respiratory support in patients with hypoxemic or hypercarbic respiratory failure or with signs of respiratory distress that were considered to require intubation; or (2) as a preventive measure in patients with high risk for extubation failure. Between 2008 and 2011, there were 107 episodes of NPPV use in 82 patients. Their median age was 57 days (range 1 day to 18 years), and weight was 4.1 kg (range 1.7-68). Within the first hour of NPPV, partial pressure of carbon dioxide/fraction of inspired oxygen (PaO2/FiO2) was significantly increased, and arterial pCO2, and respiratory rate were decreased. This decrease in respiratory rate and increase in PaO 2/FiO2 continued during the first 24 h of therapy, and pCO2 was decreased during the first 6 h. In 59.8% of cases, NPPV was successfully used without the need for tracheal intubation. The Aristotle Basic Complexity score, presence of infection, residual cardiac defect, and pH <7.36 in the first hour were independent predictors of NPPV failure. We conclude that NPPV improved oxygenation and decreased respiratory effort in pediatric cardiac patients, 59.8% of whom eventually did not receive intubation. A high-complexity surgical score, presence of infection, residual cardiac defect, and pH <7.36 in the first hour are predictors of NPPV failure, which occurs in most patients >24 h after the onset of therapy.

The relationship between in-house attending coverage and nighttime extubation following congenital heart surgery*

OBJECTIVES

Many cardiac ICUs have instituted 24/7 attending physician in-house coverage, which theoretically may allow for more expeditious weaning from ventilation and extubation. We aimed to determine whether this staffing strategy impacts rates of nighttime extubation and duration of mechanical ventilation.

DESIGN

National data were obtained from the Virtual PICU System database for all patients admitted to the cardiac ICU following congenital heart surgery in 2011 who required postoperative mechanical ventilation. Contemporaneous data from our local institution were collected in addition to the Virtual PICU System data. The combined dataset (n = 2,429) was divided based on the type of nighttime staffing model in order to compare rates of nighttime extubation and duration of mechanical ventilation between units that used an in-house attending staffing strategy and those that employed nighttime residents, fellows, or midlevel providers only.

MEASUREMENTS AND MAIN RESULTS

Institutions that currently use 24/7 in-house attending coverage did not demonstrate statistically significant differences in rates of nighttime extubation or the duration of mechanical ventilation in comparison to units without in-house attendings. Younger patients cared for in non-in-house attending units were more likely to require reintubation.

CONCLUSIONS

Pediatric patients who have undergone congenital heart surgery can be safely and effectively extubated without the routine presence of an attending physician. The utilization of nighttime in-house attending coverage does not appear to have significant benefits on the rate of nighttime extubation and may not reduce the duration of mechanical ventilation in units that already use in-house residents, fellows, or other midlevel providers.