Derivation and Validation of an Objective Effort of Breathing Score in Critically Ill Children

A 30-Minute Spontaneous Breathing Trial Misses Many Children Who Go On to Fail a 120-Minute Spontaneous Breathing Trial

BACKGROUND

The optimal length of spontaneous breathing trials (SBTs) in children is unknown.

RESEARCH QUESTIONS

What are the most common reasons for SBT failure in children, and when do they occur? Can clinical parameters at the 30-min mark of a 120-min SBT predict outcome?

STUDY DESIGN AND METHODS

We performed a secondary analysis of a clinical trial in pediatric ARDS, in which 2-h SBTs are conducted daily. SBT failure is based on objective criteria, including esophageal manometry for effort of breathing, categorized as passage, early failure (≤ 30 min), or late failure (30-120 min). Spirometry was used to calculate respiratory rate (RR), tidal volume (Vt), and rapid shallow breathing index (RSBI), in addition to pulse oximetry and capnography. Predictive models evaluated parameters at 30 min against SBT outcome, using receiver operating characteristic plots and area under the curve.

RESULTS

We included 100 children and 305 SBTs, with 42% of SBTs being successful, 32% failing within 30 min, and 25% failing between 30 and 120 min. Of the patients passing SBTs at 30 min, 40% went on to fail by 120 min. High respiratory effort (esophageal manometry) was present in > 80% of failed SBTs. At the 30-min mark, there were no clear thresholds for RR, Vt, RSBI, Fio2, oxygen saturation, or capnography that could reliably predict SBT outcome. Multivariable modeling identified RR (P < .001) and RSBI > 7 (P = .034) at 30 min, pre-SBT inspiratory pressure level (P = .009), and pre-SBT retractions (P = .042) as predictors for SBT failure, but this model performed poorly in an independent validation set with the receiver operating characteristic plot crossing the reference line (area under the curve, 0.67).

INTERPRETATION

A 30-min SBT may be too short in children recovering from pediatric ARDS because many go on to fail between 30 and 120 min. Reassuring values of Vt, RR, and gas exchange at 30 min do not reliably predict SBT passage at 2 h, likely because they do not capture the effort of breathing.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov; No.: NCT03266016; URL: www.

CLINICALTRIALS

gov.

Predicting High-Flow Nasal Cannula Therapy Outcomes Using the ROX-HR Index in the Pediatric ICU

BACKGROUND

High-flow nasal cannula (HFNC) use is increasing in pediatric patients. Objective measures that predict HFNC outcomes are lacking. The respiratory rate-oxygenation (ROX) and ROX heart rate (ROX-HR) indices are validated to predict HFNC therapy failure in adults. This study examined the performance of both indices in predicting HFNC therapy failure in children admitted to the pediatric ICU (PICU).

METHODS

This retrospective, longitudinal, observational cohort study was completed in a 24-bed PICU in a quaternary care children's hospital. All subjects ≤ 24 months of age initiated on HFNC in the PICU from January 1, 2018-August 31, 2020, were included. The ROX and ROX-HR indices were collected at standardized time points during HFNC therapy. Performance in predicting HFNC failure was evaluated using area under the receiver operating characteristic curve (AUROC) and Kaplan-Meier survival analysis. Failure was defined as escalation of respiratory support to either noninvasive ventilation or endotracheal intubation.

RESULTS

Among 446 subject encounters, 111 (24.9%) failed HFNC therapy. HFNC failure was associated with lower ROX and ROX-HR indices at termination compared to HFNC liberation (P < .001). A ROX-HR index < 3 was significantly associated with a higher risk of HFNC failure at 1 (AUROC 0.76, P = .01) and 6 (AUROC 0.81, P = .02) h.

CONCLUSIONS

ROX-HR may be a useful tool for early identification of patients ≤ 24 months at risk for HFNC failure and allow for earlier intervention. Larger prospective studies are necessary to validate the utility of the ROX-HR index in pediatric patients.

Diaphragm Ultrasonography to Predict Noninvasive Respiratory Treatment Failure in Infants With Severe Bronchiolitis

BACKGROUND

Noninvasive respiratory support is commonly used in treatment of bronchiolitis. Determinants of failure are needed to prevent delayed intubation.

METHODS

We conducted a prospective observational pilot study in infants admitted to a pediatric ICU. Diaphragmatic excursion (dExc), diaphragmatic inspiratory/expiratory time, and diaphragmatic thickening fraction (dTF) were recorded at admission, 24 h, and 48 h in both hemidiaphragms.

RESULTS

Twenty-six subjects were included (14 on HFNC and 12 on NIV) with a total of 56 ultrasonographic evaluations. Three subjects required invasive ventilation. Sixty-four percent of the subjects on HFNC required NIV as rescue therapy and 2/14 invasive ventilation (14.2%). In the HFNC group there were no differences in dExc between those who required escalation to NIV or invasive ventilation and those who didn't. Left dTF was higher in subjects on HFNC requiring invasive ventilation versus those needing NIV (left dTF 47% vs 22% [13-30]; P = .046, r = 0.7). Diaphragmatic I:E ratios were higher in infants on HFNC requiring invasive ventilation and diaphragmatic expiratory time was shorter (left P = .038; right P = .02). In the NIV group there were no differences in dExc, I:E ratios, or dTF between subjects needing escalation to invasive ventilation and those who didn't. We found no correlation between a clinical work of breathing score and echographic dTF.

CONCLUSIONS

In infants with moderate or severe bronchiolitis receiving HFNC, the use of ultrasonographic left dTF could help predict respiratory treatment failure and need for invasive ventilation. The use of ultrasonographic dExc is of little help to predict both.

Implementation of a High-Flow Nasal Cannula Management Protocol in the Pediatric ICU

BACKGROUND

High-flow nasal cannula (HFNC) therapy is a respiratory modality that has been adopted to support pediatric patients with bronchiolitis. There is no standardized protocol for initiation, escalation, or weaning of HFNC in the pediatric ICU. The aim of this respiratory therapist (RT)-driven quality improvement management protocol was to decrease duration of HFNC.

METHODS

An RT-driven HFNC management protocol based on an objective respiratory score was implemented in 2017 at a quaternary care children's hospital. Subjects included children less than 2 y old admitted to the pediatric ICU with bronchiolitis. All subjects needing HFNC were scored and placed within the protocol as appropriate for age, then weaned or escalated per the scoring tool. Comparison to a pre-intervention control group was performed. Average HFNC duration per subject was used as the primary outcome measure. Protocol compliance was used as a process measure. Noninvasive ventilation use, intubation rate, and 30-d pediatric ICU readmission rate were used as balancing measures. RT satisfaction with HFNC management before and after protocol implementation were measured.

RESULTS

Protocol compliance was sustainable and above the goal of 80% after 4 months of protocol implementation. HFNC duration decreased from 2.5 d to 2 days for each subject during planning and then to 1.8 d after protocol implementation. Length of stay (LOS) in the pediatric ICU and hospital LOS decreased from 2.6 d to 2.1 d and from 5.7 d to 4.7 d after protocol implementation, respectively. The use of noninvasive ventilation and the rate of intubation did not change significantly. RTs reported increased involvement in HFNC management decisions and appropriateness on how quickly the team weaned HFNC.

CONCLUSIONS

An RT-driven HFNC management protocol was safely implemented in a pediatric ICU and decreased HFNC duration, pediatric ICU LOS, and hospital LOS. It allows the RT to work independently to the highest extent of their scope of practice, leading to improvement in RT job satisfaction.

Interobserver Agreement on Clinical Judgment of Work of Breathing in Spontaneously Breathing Children in the Pediatric Intensive Care Unit

Clinical assessment of the work of breathing (WOB) remains a cornerstone in respiratory support decision-making in the pediatric intensive care unit (PICU). In this study, we determined the interobserver agreement of 30 observers (PICU physicians and nurses) on WOB and multiple signs of effort of breathing in 10 spontaneously breathing children admitted to the PICU. By reliability analysis, the agreement on overall WOB was poor to moderate, and only three separate signs of effort of breathing (breathing rate, stridor, and grunting) showed moderate-to-good interobserver reliability. We conclude that the interobserver agreement on the clinical WOB judgment among PICU physicians and nurses is low.