Elsevier

The Journal of Pediatrics

Volume 189, October 2017, Pages 66-71.e3
The Journal of Pediatrics

Original Articles
The Relationship between High Flow Nasal Cannula Flow Rate and Effort of Breathing in Children

https://doi.org/10.1016/j.jpeds.2017.06.006Get rights and content

Objective

To use an objective metric of effort of breathing to determine optimal high flow nasal cannula (HFNC) flow rates in children <3 years of age.

Study design

Single-center prospective trial in a 24-bed pediatric intensive care unit of children <3 years of age on HFNC. We measured the percent change in pressure∙rate product (PRP) (an objective measure of effort of breathing) as a function of weight-indexed flow rates of 0.5, 1.0, 1.5, and 2.0 L/kg/minute. For a subgroup of patients, 2 different HFNC delivery systems (Fisher & Paykel [Auckland, New Zealand] and Vapotherm [Exeter, New Hampshire]) were compared.

Results

Twenty-one patients (49 titration episodes) were studied. The most common diagnoses were bronchiolitis and pneumonia. Overall, there was a significant difference in the percent change in PRP from baseline (of 0.5 L/kg/minute) with increasing flow rates for the entire cohort (P < .001) with largest change at 2.0 L/kg/min (−21%). Subgroup analyses showed no significant difference in percent change in PRP from baseline when comparing the 2 different HFNC delivery systems (P = .12). Patients ≤8 kg experienced a larger percent change in PRP as HFNC flow rates were increased (P = .001) than patients >8 kg.

Conclusions

The optimal HFNC flow rate to reduce effort of breathing in infants and young children is approximately 1.5-2.0 L/kg/minute with more benefit seen in children ≤8 kg.

Section snippets

Methods

We performed a single-center prospective trial in the 24-bed multidisciplinary medical-surgical pediatric intensive care unit at Children's Hospital Los Angeles (CHLA) from September 2014 to June 2016. This study was approved by the CHLA institutional review board, and informed consent was obtained. All patients ≤3 years of age admitted to the CHLA pediatric intensive care unit and placed on HFNC by the clinical team were eligible. We excluded patients if they had a corrected gestational age

Results

A total of 54 patients meeting inclusion criteria were approached, and 21 patients were consented and studied for a total of 49 titration episodes. Demographic and clinical characteristics were recorded (Table) and patients screened and studied are described in a CONSORT diagram (Figure 2; available at www.jpeds.com). The most common reason consent was refused was related to placement of the esophageal catheter.

Analyzing all titration episodes on all types of HFNC delivery systems, the median

Discussion

Using esophageal manometry to capture a direct metric of effort of breathing (PRP), we have demonstrated that increasing weight-indexed flow rates of HFNC (up to 2.0 L/kg/minute) decrease effort of breathing in a dose-dependent fashion with the largest effect seen in lighter children.

In the setting of respiratory illness, patients increase effort of breathing to maintain ventilation and oxygenation and compensate for changes in airway resistance and pulmonary compliance. Fundamentally,

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    Vapotherm, Inc. provided a limited number of high flow nasal cannula delivery systems for use in this study but this company did not have any role in (1) study design, (2) collection, analysis, and interpretation of data, (3) the writing of the report, or (4) the decision to submit the paper for publication. The authors declare no conflicts of interest.

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