Ultrasound assessment of diaphragm thickness, contractility, and strain in healthy pediatric patients.

BACKGROUND: Ultrasound-based diaphragmatic assessments are becoming more common in pediatric acute care, but baseline pediatric diaphragm thickness and contractility values remain unknown. METHODS: We conducted a prospective, observational study of healthy children aged <18 years undergoing elective surgery. Diaphragm thickness at end-expiration (Tdi-exp), thickening fraction (DTF) and excursion were measured by ultrasound during spontaneous breathing and during mechanical ventilation. Diaphragm strain and peak strain rate were ascertained post hoc. Measurements were compared across a priori specified age groups (<1 year, 1 to <3, 3 to <6, 6 to <12, and 12 to <18 years) and with versus without mechanical ventilation. RESULTS: Fifty subjects were evaluated (n = 10 per age group). Baseline mean Tdi-exp was 0.19 ± 0.04 cm, DTF 0.19 ± 0.09, excursion 1.69 ± 0.97 cm, strain -10.3 ± 4.9, peak strain rate -0.48 ± 0.21 s-1 . No significant difference in Tdi-exp or DTF was observed across age groups (p > .05). Diaphragm excursion increased with age (p < .0001). Diaphragm strain was significantly greater in the 12-17-year age group (-14.3 ± 6.4), p = .048, but there were no age-related differences in peak strain rate (p = .08). During mechanical ventilation, there were significant decreases in DTF 0.12 ± 0.04 (p < .0001), excursion 1.08 ± 0.31 cm (p < .0001), strain -4.60 ± 1.93 (p < .0001), and peak strain rate -0.20 ± 0.10 s-1 (p < .0001) while there was no change in Tdi-exp 0.18 ± 0.03 cm (p = .25) when compared to baseline values. CONCLUSION: Pediatric Tdi-exp, DTF, and diaphragm peak strain rate were similar across age groups. Diaphragm excursion and strain varied across age groups. All measures of diaphragm contractility were diminished during mechanical ventilation.

Noninvasive Positive Pressure Ventilation Use and In-Hospital Cardiac Arrest in Bronchiolitis.

IMPORTANCE: A recent study showed an association between high hospital-level noninvasive positive pressure ventilation (NIPPV) use and in-hospital cardiac arrest (IHCA) in children with bronchiolitis. OBJECTIVES: We aimed to determine if patient-level exposure to NIPPV in children with bronchiolitis was associated with IHCA. DESIGN, SETTING AND PARTICIPANTS: Retrospective cohort study at a single-center quaternary PICU in North America including children with International Classification of Diseases primary or secondary diagnoses of bronchiolitis in the Virtual Pediatric Systems database. MAIN OUTCOMES AND MEASURES: The primary exposure was NIPPV and the primary outcome was IHCA. MEASUREMENTS AND MAIN RESULTS: Of 4698 eligible ICU admissions with bronchiolitis diagnoses, IHCA occurred in 1.2% (57/4698). At IHCA onset, invasive mechanical ventilation (IMV) was the most frequent level of respiratory support (65%, 37/57), with 12% (7/57) receiving NIPPV. Patients with IHCA had higher Pediatric Risk of Mortality-III scores (3 [0-8] vs. 0 [0-2]; p < 0.001), more frequently had a complex chronic condition (94.7% vs. 46.2%; p < 0.001), and had higher mortality (21.1% vs. 1.0%; p < 0.001) compared with patients without IHCA. Return of spontaneous circulation (ROSC) was achieved in 93% (53/57) of IHCAs; 79% (45/57) survived to hospital discharge. All seven children without chronic medical conditions and with active bronchiolitis symptoms at the time of IHCA achieved ROSC, and 86% (6/7) survived to discharge. In multivariable analysis restricted to patients receiving NIPPV or IMV, NIPPV exposure was associated with lower odds of IHCA (adjusted odds ratio [aOR], 0.07; 95% CI, 0.03-0.18) compared with IMV. In secondary analysis evaluating categorical respiratory support in all patients, compared with IMV, NIPPV was associated with lower odds of IHCA (aOR, 0.35; 95% CI, 0.14-0.87), whereas no difference was found for minimal respiratory support (none/nasal cannula/humidified high-flow nasal cannula [aOR, 0.56; 95% CI, 0.23-1.36]). CONCLUSIONS AND RELEVANCE: Cardiac arrest in children with bronchiolitis is uncommon, occurring in 1.2% of bronchiolitis ICU admissions. NIPPV use in children with bronchiolitis was associated with lower odds of IHCA.

Pediatric in-hospital cardiac arrest: Respiratory failure characteristics and association with outcomes.

AIMS: To characterize respiratory failure prior to pediatric in-hospital cardiac arrest (IHCA) and to associate pre-arrest respiratory failure characteristics with survival outcomes. METHODS: This is a single-center, retrospective cohort study from a prospectively identified cohort of children <18 years in intensive care units (ICUs) who received cardiopulmonary resuscitation (CPR) for ≥1 minute between January 1, 2017 and June 30, 2021, and were receiving invasive mechanical ventilation (IMV) in the hour prior to IHCA. Patient characteristics, ventilatory support and gas exchange immediately pre-arrest were described and their association with the return of spontaneous circulation (ROSC) was measured. RESULTS: In the 187 events among 154 individual patients, the median age was 0.9 [0.2, 2.4] years, and CPR duration was 7.5 [3, 29] minutes. Respiratory failure was acute prior to 106/187 (56.7%) events, and the primary indication for IMV was respiratory in nature in 107/187 (57.2%) events. Immediately pre-arrest, the median positive end-expiratory pressure was 8 [5, 10] cmH2O; mean airway pressure was 13 [10,18] cmH2O; peak inspiratory pressure was 28 [24, 35] cmH2O; and fraction of inhaled oxygen (FiO2) was 0.40 [0.25, 0.80]. Pre-arrest FiO2 was lower in patients with ROSC vs. without ROSC (0.30 vs. 0.99; p < 0.001). Patients without ROSC had greater severity of pre-arrest oxygenation failure (p < 0.001) as defined by oxygenation index, oxygen saturation index, P/F ratio or S/F ratio. CONCLUSIONS: There was substantial heterogeneity in respiratory failure characteristics and ventilatory requirements pre-arrest. Higher pre-arrest oxygen requirement and greater degree of oxygenation failure were associated with worse survival outcomes.