High-frequency oscillatory ventilation in children with acute respiratory distress syndrome: experience of a pediatric intensive care unit

The effect of high-frequency oscillatory ventilation or airway pressure release ventilation on children with acute respiratory distress syndrome as a rescue therapy

BACKGROUND

To investigate the effects of high-frequency oscillatory ventilation (HFOV) or airway pressure release ventilation (APRV) as a rescue therapy on children with moderate and severe acute respiratory distress syndrome (ARDS).

METHODS

We retrospectively enrolled 47 children with ARDS who were transitioned from synchronized intermittent mandatory ventilation (SIMV) to either HFOV or APRV for 48 h or longer after failure of SIMV. The parameters of demographic data, arterial blood gases, ventilator settings, oxygenation index (OI), and PaO₂/FiO₂ (PF) ratio during the first 48 h of HFOV and APRV were recorded.

RESULTS

There was no significant difference between the HFOV and APRV groups with survival rates of 60% and 72.7%, respectively. Compared to pre-transition, the mean airway pressures at 2 and 48 h after transition were higher in both groups (P<0.01), and the PF ratio at 2 and 48 h in both modes was significantly improved (P<0.001). PF ratio and PaCO₂ have significant differences at 48 h between two groups. The OI at 2 h after transition had no improvement in either group and was substantially lower at 48 h relative to the pre-transition level (P<0.001) in both groups. At 48 h after the transition to both HFOV and APRV, the survivors had lower mean airway pressures, higher PF ratios, and a lower OIs than non-survivors (P<0.01).

CONCLUSIONS

There was no significant difference on the survival rates of HFOV and APRV application as a rescue therapy for ARDS, but improved oxygenation at 48 h reliably discriminated survivors from non-survivors in both groups.

Outcomes of Severe PARDS on High-Frequency Oscillatory Ventilation - A Single Centre Experience

OBJECTIVE

To describe experience with high-frequency oscillatory ventilation (HFOV) in children with acute respiratory distress syndrome (ARDS) transitioned from conventional mechanical ventilation (CMV) due to refractory hypoxemia and to assess factors associated with survival and also compare outcomes of patients who were managed with early HFOV (within 24 h of intubation) vs. late HFOV.

METHODS

This retrospective, observational study was conducted in a tertiary care hospital's pediatric intensive care unit. Thirty-four children with pediatric acute respiratory distress syndrome (PARDS) managed with HFOV were included.

RESULTS

Of 34 children with PARDS managed with HFOV after failure of conventional ventilation to improve oxygenation, 8 survived. Improvement in the Oxygenation Index (OI) at 48 h of initiation of HFOV along with percent increase in PaO₂/FiO₂ (P/F ratio) at 24 h of HFOV were predictors of survival. The response to HFOV, based on OI and P/F ratio, between 24 and 48 h of ventilation identified potential survivors. Also, lower positive end-expiratory pressure (PEEP) on CMV and shorter duration of CMV before initiation of HFOV were associated with survival.

CONCLUSIONS

Survival in pediatric ARDS patients treated with HFOV could be predicted by using trends of OI - with survivors showing a more rapid decline in OI between 24 and 48 h of initiation compared to non-survivors.

The impact of high frequency oscillatory ventilation on mortality in paediatric acute respiratory distress syndrome

BACKGROUND

High-frequency oscillatory ventilation (HFOV) use was associated with greater mortality in adult acute respiratory distress syndrome (ARDS). Nevertheless, HFOV is still frequently used as rescue therapy in paediatric acute respiratory distress syndrome (PARDS). In view of the limited evidence for HFOV in PARDS and evidence demonstrating harm in adult patients with ARDS, we hypothesized that HFOV use compared to other modes of mechanical ventilation is associated with increased mortality in PARDS.

METHODS

Patients with PARDS from 10 paediatric intensive care units across Asia from 2009 to 2015 were identified. Data on epidemiology and clinical outcomes were collected. Patients on HFOV were compared to patients on other modes of ventilation. The primary outcome was 28-day mortality and secondary outcomes were 28-day ventilator- (VFD) and intensive care unit- (IFD) free days. Genetic matching (GM) method was used to analyse the association between HFOV treatment with the primary outcome. Additionally, we performed a sensitivity analysis, including propensity score (PS) matching, inverse probability of treatment weighting (IPTW) and marginal structural modelling (MSM) to estimate the treatment effect.

RESULTS

A total of 328 patients were included. In the first 7 days of PARDS, 122/328 (37.2%) patients were supported with HFOV. There were significant differences in baseline oxygenation index (OI) between the HFOV and non-HFOV groups (18.8 [12.0, 30.2] vs. 7.7 [5.1, 13.1] respectively; p < 0.001). A total of 118 pairs were matched in the GM method which found a significant association between HFOV with 28-day mortality in PARDS [odds ratio 2.3, 95% confidence interval (CI) 1.3, 4.4, p value 0.01]. VFD was indifferent between the HFOV and non-HFOV group [mean difference - 1.3 (95%CI - 3.4, 0.9); p = 0.29] but IFD was significantly lower in the HFOV group [- 2.5 (95%CI - 4.9, - 0.5); p = 0.03]. From the sensitivity analysis, PS matching, IPTW and MSM all showed consistent direction of HFOV treatment effect in PARDS.

CONCLUSION

The use of HFOV was associated with increased 28-day mortality in PARDS. This study suggests caution but does not eliminate equivocality and a randomized controlled trial is justified to examine the true association.

[A Meta analysis of the efficacy of high-frequency oscillatory ventilation versus conventional mechanical ventilation for treating pediatric acute respiratory distress syndrome]

OBJECTIVE

To systematically assess the clinical efficacy of high-frequency oscillatory ventilation (HFOV) and conventional mechanical ventilation (CMV) for treating pediatric acute respiratory distress syndrome (ARDS).

METHODS

Data from randomized controlled trials comparing HFOV and CMV in the treatment of pediatric ARDS published before July 2016 were collected from the Cochrane Library, PubMed, Medline, CNKI, and Wanfang Data. Literature screening, data extraction, and quality assessment were performed by two independent reviewers according to the inclusion and exclusion criteria. The selected studies were then subjected to a Meta analysis using the RevMan 5.3 software.

RESULTS

A total of 6 studies involving 246 patients were included. The results of the Meta analysis showed that there were no significant differences between the HFOV and CMV groups in the in-hospital or 30-day mortality rate, incidence of barotrauma, mean ventilation time, and oxygenation index (P>0.05). However, compared with CMV, HFOV increased the PaO₂/FiO₂ ratio by 17%, 24%, and 31% at 24, 48, and 72 hours after treatment respectively, and improved oxygenation in patients.

CONCLUSIONS

Although the mortality rate is not reduced by HFOV in children with ARDS, this treatment can result in significant improvement in oxygenation compared with CMV. Further large-sample, multicenter, randomized clinical trials will be required to draw a definitive conclusion.

Is there still a role for high-frequency oscillatory ventilation in neonates, children and adults?

Critically ill patients with respiratory pathology often require mechanical ventilation and while low tidal volume ventilation has become the mainstay of treatment, achieving adequate gas exchange may not be attainable with conventional ventilator modalities. In attempt to achieve gas exchange goals and also mitigate lung injury, high frequency ventilation is often implemented which couples low tidal volumes with sustained mean airway pressure. This manuscript presents the physiology of high-frequency oscillatory ventilation, reviews the currently available data on its use and provides strategies and approaches for this mode of ventilation.

High-frequency oscillatory ventilation combined with partial liquid ventilation in experimental lung injury: effects on lung cell apoptosis

Objective

To investigate the effects of high-frequency oscillatory ventilation (HFOV) and partial liquid ventilation (PLV) on apoptosis of lung tissue induced by steam inhalation injury in rabbit.

Design

A prospective, randomized, controlled, multiple-group study.

Setting

An animal research laboratory centre in a university burns centre.

Subjects

New Zealand rabbits (n = 32; 2.25 ± 0.25 kg) of either sex.

Interventions

The animals were ventilated by HFOV with a mean airway pressure of 10 cm H₂O, a frequency of 10 Hz, an amplitude of 20 cm H₂O, an inspiratory:expiratory ratio of 1:1, and an FiO₂ of 1.0. After the induction of acute lung injury (ALI) by steam inhalation, the animals were randomly divided into four groups: CMV, HFOV, CMV + PLV, HFOV + PLV group. Then they were ventilated for 4 h by CMV, HFOV, CMV + PLV and HFOV + PLV, respectively. After the experimental period, cell apoptosis and apoptosis indexes in the lung tissue were assessed with TUNEL FragELTM (Fragment End Labeling).

Results

Lung tissue apoptosis indexes in HFOV group and HFOV + PLV group were lower than that of in CMV group and CMV + PLV group; between-group comparison had significant difference (P < 0.01). HFOV + PLV group showed lowest apoptosis indexes.

Conclusion

HFOV combined with PLV can suppress lung tissue apoptosis induced by steam inhalation.

Epidemiology of pediatric acute respiratory distress syndrome in singapore: risk factors and predictive respiratory indices for mortality

AIM

Acute respiratory distress syndrome (ARDS) represents the most severe form of acute lung injury. The aim of our study is to describe the epidemiology of pediatric ARDS in Singapore and compare the outcomes of ARDS using the following respiratory indices: PaO2/FiO2 ratio (P/F ratio), SpO2/FiO2 ratio (S/F ratio), oxygenation index (OI), and oxygen saturation index (OSI).

METHODS

We examined medical records of patients admitted to the Children's Intensive Care Unit in KK Women's and Children's Hospital from 2009 to 2012. Those who fulfilled criteria for the American-European Consensus Conference definition for ARDS were identified. Demographic, clinical, and radiographic information were extracted and analyzed.

RESULTS

We identified 70 patients with ARDS. Median age (interquartile range) was 6.2 (1.4, 10.4) years. The most common risk factor was pneumonia [50 (71%)]. Overall mortality was 44 (63%) patients. Thirty-two (56%) patients had an underlying chronic comorbidity; 18 (46%) were hematology-oncology conditions. Fifty-six (80%) patients had multiorgan dysfunction. Adjunct therapies used in our patients included inhaled nitric oxide [5 (7%)], prone position [22 (31%)], steroids [26 (37%)], and neuromuscular blockade [26 (37%)]. A high OI and low PF ratio after 24 h of diagnosis of ARDS were associated with mortality. From day 3 onward, all four respiratory indices appropriately differentiated survivors from non-survivors. Severity based on the S/F ratio and OSI demonstrated association with decreased ventilator free days and ICU free days.

CONCLUSION

Risk factors for mortality included having an underlying comorbidity, multiorgan dysfunction, a low PF ratio, and high OI at 24 h of ARDS. Abnormal SpO2-based measurements were reliable markers of poor outcomes in pediatric ARDS.