Feasibility of an alternative, physiologic, individualized open-lung approach to high-frequency oscillatory ventilation in children

Abstract

BackgroundHigh-frequency oscillatory ventilation (HFOV) is a common but unproven management strategy in paediatric critical care. Oscillator settings have been traditionally guided by patient age and/or weight rather than by lung mechanics, thereby potentially negating any beneficial effects. We have adopted an open-lung HFOV strategy based on a corner frequency approach using an initial incremental–decremental mean airway pressure titration manoeuvre, a high frequency (8–15 Hz), and high power to initially target a proximal pressure amplitude (∆Pproximal) of 70–90 cm H2O, irrespective of age or weight.MethodsWe reviewed prospectively collected data on patients < 18 years of age who were managed with HFOV for acute respiratory failure. We measured metrics for oxygenation, ventilation, and haemodynamics as well as the use of sedative-analgesic medications and neuromuscular blocking agents.ResultsData from 115 non-cardiac patients were analysed, of whom 53 had moderate-to-severe paediatric acute respiratory distress syndrome (PARDS). Sixteen patients (13.9%) died. Frequencies≥ 8 Hz and high ∆Pproximal were achieved in all patients irrespective of age or PARDS severity. Patients with severe PARDS showed the greatest improvement in oxygenation. pH and PaCO2 normalized in all patients. Haemodynamic parameters, cumulative amount of fluid challenges, and daily fluid balance did not deteriorate after transitioning to HFOV in any age or PARDS severity group. We observed a transient increase neuromuscular blocking agent use after switching to HFOV, but there was no increase in the daily cumulative amount of continuous midazolam or morphine in any age or PARDS severity group. No patients experienced clinically apparent barotrauma.ConclusionsThis is the first study reporting the feasibility of an alternative, individualized, physiology-based open-lung HFOV strategy targeting high F and high ∆Pproximal. No adverse effects were observed with this strategy. Our findings warrant further systematic evaluation.

High-frequency oscillatory ventilation in a tertiary paediatric intensive care unit in an academic hospital in Johannesburg, South Africa

“…[1] The rate of escalation of initial Paw on HFOV may also have relevance, given the lower incidence of haemodynamic instability in a recent feasibility study, where Paw was increased gradually using the researchers' individualised approach, despite final magnitudes of Paw change occurring that were similar to those in the present study. [25] The incidence of pneumothoraces was also higher (11.8%) than in recent reported studies. [3,8,12,18,22] Of note was the fact that three of the four patients with pneumothoraces were exposed to a substantial increase in Paw of 8 -10 cmH 2 O when transitioned to HFOV.…”

Physiologic responses to a staircase lung volume optimization maneuver in pediatric high-frequency oscillatory ventilation

“…We collected data during the lung volume optimization maneuver in children after the indication for HFOV was set by the attending physician in agreement with the clinical guideline [ 10 ]. Children were enrolled after written informed consent from either parents or legal caretakers if they had acute onset of lung disease and were on neuromuscular paralysis.…”

“…Frequency and power remained constant, so that the proximal pressure amplitude could reflect changes in respiratory system compliance. Only in patients with severe increasing hypercapnia resulting in acidosis (pH < 7.25), frequency was lowered during the maneuver [ 10 ].…”

“…One approach to a lung volume optimization maneuver is the staircase incremental-decremental pressure titration [10][11][12]. Since it has been proposed that oxygenation improves linearly with increases in lung volume during HFOV, the transcutaneous measured oxygen saturation (SpO 2 ) in relation to the delivered oxygen fraction (FiO 2 ) drives the pressure titration.…”

Response to the authors

“…We like to thank the authors for their interest in our manuscript and their positive feedback. High-frequency oscillatory ventilation (HFOV) is used in our unit for any type of PARDS when the patient meets specific criteria as outlined in our manuscript (in summary, peak inspiratory pressure [PIP] > 28-32 cm H 2 O, PEEP > 8 cm H 2 O, FiO 2 > 0.60, and oxygenation index [OI] increases on three consecutive 1-h measurements despite increasing PEEP) [1]. We understand the author's perspective that HFOV might be more effective in certain types of PARDS, but we advocate that HFOV should not only be considered in case of refractory hypoxaemia, but also when the bedside team wants to prevent ventilator settings becoming toxic.…”