Effects Of High Frequency Oscillatory Ventilation Research Articles

Heterogeneous Treatment Effects of High-Frequency Oscillatory Ventilation for Acute Respiratory Distress Syndrome: A Post Hoc Analysis of the Oscillation for Acute Respiratory Distress Syndrome Treated Early (OSCILLATE) Trial

OBJECTIVES: We sought to evaluate whether different subgroups of adults with acute respiratory distress syndrome (ARDS) respond differently to high-frequency oscillatory ventilation (HFOV). DESIGN: The Oscillation for ARDS Treated Early (OSCILLATE) trial was a randomized controlled trial of HFOV vs. conventional ventilation that found an increased risk of in-hospital mortality (primary outcome) with HFOV. In a post hoc analysis, we applied three different approaches to evaluate heterogeneity of treatment effect for in-hospital mortality: 1) subgroup analyses based on baseline Pao 2:Fio 2 ratio and oxygenation index (OI); 2) a risk-based approach using a multivariable outcome prediction model; and 3) a clustering approach via multivariable latent class analysis. We used multivariable logistic regression models to assess for interaction. SETTING: Thirty-nine ICUs, five countries. SUBJECTS: Five hundred forty-eight adults with moderate to severe ARDS. INTERVENTIONS: HFOV vs. conventional mechanical ventilation with low tidal volume and higher positive end-expiratory pressure. MEASUREMENTS AND MAIN RESULTS: The effect of HFOV on in-hospital mortality was consistent across categories of Pao 2:Fio 2 ratio (adjusted odds ratio [aOR], 2.04; 95% CI, 1.32–3.17 and aOR, 1.16; 95% CI, 0.49–2.75 for groups with Pao 2:Fio 2 above or equal to 80, vs. below 80, respectively; interaction p = 0.23) and OI (aOR, 1.78; 95% CI, 0.67–4.70; aOR, 3.19; 95% CI, 1.44–7.09; aOR, 1.73; 95% CI, 0.82–3.65; and aOR, 1.33; 95% CI, 0.61–2.90 for quartiles of baseline OI, respectively; interaction p = 0.44). Point estimates for the effect of HFOV were consistent across risk categories (aOR, 2.44; 95% CI, 0.40–14.83; aOR, 1.69; 95% CI, 0.75–3.85; and aOR, 2.10; 95% CI, 0.59–7.54 for the lowest, moderate, and highest risk categories, respectively; interaction p = 0.32). Using a clustering approach, point estimates for HFOV were also consistent (cluster 1: aOR, 1.85; 95% CI, 1.15–3.00 and cluster 2: aOR, 1.75; 95% CI, 0.91–3.38; interaction p = 0.75). CONCLUSIONS: We did not identify heterogeneity in the effect of HFOV across different subgroups of patients with ARDS.

Effect of High-Frequency Oscillatory Ventilation, Combined With Prone Positioning, in Infants With Acute Respiratory Distress Syndrome After Congenital Heart Surgery: A Prospective Randomized Controlled Trial

ObjectivesThis study aimed to evaluate the effect of high-frequency oscillatory ventilation, (HFOV) combined with prone positioning, on oxygenation and pulmonary ventilation in infants with acute respiratory distress syndrome (ARDS) after congenital heart surgery.DesignA randomized controlled trial.SettingA single-center study at a tertiary teaching hospital.ParticipantsPatients with postoperative ARDS after congenital heart disease were divided randomly into the following 2 groups: HFOV combined with prone position (HFOV-PP), and HFOV combined with supine position (HFOV-SP).InterventionsThe primary outcomes were the PaO2/FIO2 ratio and the oxygenation index after the intervention, and the secondary outcomes were respiratory variables, hemodynamics, complications, and other short-term outcomes.ResultsSixty-five eligible infants with ARDS were randomized to either the HFOV-PP (n = 32) or HFOV-SP (n = 33) group. No significant difference in baseline data was found between the 2 groups (p > 0.05). Oxygenation was improved in both groups after HFOV intervention. Compared with the HFOV-SP group, the HFOV-PP group had significantly increased PaO2/FIO2 and oxygenation index and a shorter duration of invasive ventilation and length of cardiac intensive care unit stay. No serious complications occurred in the 2 groups.ConclusionHFOV-PP significantly improved oxygenation in infants with ARDS after cardiac surgery and had no serious complications.

Effects of High-Frequency Oscillatory Ventilation With Volume Guarantee During Surfactant Treatment in Extremely Low Gestational Age Newborns With Respiratory Distress Syndrome: An Observational Study.

ObjectiveTo evaluate the effect of volume guarantee (VG) combined with high-frequency oscillatory ventilation (HFOV) on respiratory and other physiological parameters immediately after lung recruitment and surfactant administration in HFOV elective ventilated extremely low gestational age newborns (ELGAN) with respiratory distress syndrome (RDS).DesignObservational study.SettingTertiary neonatal intensive care unit.PatientsTwenty-two ELGANs of 25.5 ± 1.1 weeks of gestational age requiring invasive mechanical ventilation and surfactant administration for RDS during the first 6 h of life.InterventionsAll infants intubated in delivery room, were managed with elective HFOV and received surfactant after a lung recruitment manoeuver. Eleven infants received HFOV + VG and were compared with a control group of 11 infants receiving HFOV alone. HFOV was delivered in both groups by Dräger Babylog VN500 ventilator (Dräger, Lubeck, Germany).Main Outcome MeasuresVariations and fluctuations of delivered high-frequency tidal volume (VThf), fluctuation of pressure amplitude (ΔP) and partial pressure of CO2 (pCO2) levels after recruitment manoeuver and immediately after surfactant administration, in HFOV + VG vs. HFOV ventilated infants.ResultsThere were no significant differences in the two groups at starting ventilation with or without VG. The mean applied VThf per kg was 1.7 ± 0.3 ml/kg in the HFOV group and 1.7 ± 0.1 ml/kg in the HFOV + VG group. Thirty minutes after surfactant administration, HFOV group had a significant higher VThf/Kg than HFOV + VG (2.1 ± 0.3 vs. 1.6 ± 0.1 ml/kg, p < 0.0001) with significantly lower pCO2 levels (43.1 ± 3.8 vs. 46.8 ± 1.5 mmHg, p = 0.01), 54.4% of patients having pCO2 below 45 mmHg. Measured post-surfactant ΔP values were higher in HFOV group (17 ± 3 cmH2O) than in HFOV + VG group (13 ± 3 cmH2O, p = 0.01).ConclusionHFOV + VG maintains pCO2 levels within target range and reduces VThf delivered variations more consistently than HFOV alone after surfactant administration.

Effect of High-Frequency Oscillatory Ventilation Combined With Pulmonary Surfactant in the Treatment of Acute Respiratory Distress Syndrome After Cardiac Surgery: A Prospective Randomised Controlled Trial.

Background: This study aimed to evaluate the effects of pulmonary surfactant (PS) combined with high-frequency oscillatory ventilation (HFOV) or conventional mechanical ventilation (CMV) in infants with acute respiratory distress syndrome (ARDS) after congenital cardiac surgery.Methods: A total of 61 infants with ARDS were eligible and were randomised to the CMV + PS group (n = 30) or the HFOV + PS group (n = 31) between January 2020 and December 2020. The primary outcomes were the changes in arterial blood gas parameters. The duration of mechanical ventilation, length of hospitalisation and the incidence of complications were considered secondary outcomes.Results: A total of 61 infants completed the study. In the HFOV + PS group, the blood gas analysis results were significantly improved (P < 0.05), while the duration of mechanical ventilation and length of hospitalisation were shorter than the CMV + PS group (P < 0.05). However, the incidence of complications was not different between the two groups (P > 0.05).Conclusions: Compared with the CMV + PS group, the HFOV + PS group showed significantly improved ABG variables and had a shortened length of hospitalisation and mechanical ventilation in infants with ARDS after cardiac surgery.Clinical Trial Registration: Chinese Clinical Trial Registry; Number: ChiCTR2000039457.

Therapeutic effects and outcomes of rescue high-frequency oscillatory ventilation for premature infants with severe refractory respiratory failure

Despite wide application of high frequency oscillatory ventilation (HFOV) in neonates with respiratory distress, little has been reported about its rescue use in preterm infants. We aimed to evaluate the therapeutic effects of HFOV in preterm neonates with refractory respiratory failure and investigate the independent risk factors of in-hospital mortality. We retrospectively analyzed data collected prospectively (January 2011–December 2018) in four neonatal intensive care units of two tertiary-level medical centers in Taiwan. All premature infants (gestational age 24–34 weeks) receiving HFOV as rescue therapy for refractory respiratory failure were included. A total of 668 preterm neonates with refractory respiratory failure were enrolled. The median (IQR) gestational age and birth weight were 27.3 (25.3–31.0) weeks and 915.0 (710.0–1380.0) g, respectively. Pre-HFOV use of cardiac inotropic agents and inhaled nitric oxide were 70.5% and 23.4%, respectively. The oxygenation index (OI), FiO2, and AaDO2 were markedly increased after HFOV initiation (all p < 0.001), and can be decreased within 24–48 h (all p < 0.001) after use of HFOV. 375 (56.1%) patients had a good response to HFOV within 3 days. The final in-hospital mortality rate was 34.7%. No association was found between specific primary pulmonary disease and survival in multivariate analysis. We found preterm neonates with gestational age < 28 weeks, occurrences of sepsis, severe hypotension, multiple organ dysfunctions, initial higher severity of respiratory failure and response to HFOV within the first 72 h were independently associated with final in-hospital mortality. The mortality rate of preterm neonates with severe respiratory failure remains high after rescue HFOV treatment. Aggressive therapeutic interventions to treat sepsis and prevent organ dysfunctions are the suggested strategies to optimize outcomes.

High-frequency oscillatory ventilation for adult patients with acute respiratory distress syndrome

Background As a new kind of ventilatory mode, high-frequency oscillatory ventilation(HFOV) is characterized by the rapid delivery of small tidal volumes cycling and high mean airway pressure. It has been successfully used in adults with the acute respiratory distress syndrome(ARDS). It has been shown that HFOV has advantages over conventional mechanical ventilation(CMV) in improving oxygenation and reducing the incidence of ventilator associated lung injury(VILI). However, the effect of HFOV on mortality still needs to be characterized. Objective To summarize the trials evaluating HFOV in adults with ARDS and reveal both the strengths and weaknesses of HFOV. Content HFOV is associated with significant improvement in oxygenation and prevention of VILI, however, not associated with reduction of mortality. Further researches are needed to identify optimal patient selection, timing, ventilator settings, and the role of combining HFOV with other interventions. Trend Further researches and explorations are needed to define the role of HFOV in adult ARDS. Key words: High-frequency oscillatory ventilation; Acute respiratory distress syndrome; Adult; Mortality

Effects of High-frequency Oscillatory Ventilation on Systemic and Cerebral Hemodynamics and Tissue Oxygenation: An Experimental Study in Pigs

In this study, we compare the effects of high frequency oscillatory ventilation (HFOV) with those of lung-protective volume-controlled ventilation (VCV) on cerebral perfusion, tissue oxygenation, and cardiac function with and without acute intracranial hypertension (AICH). Eight pigs with healthy lungs were studied during VCV with low tidal volume (V(T): 6 ml kg(-1)) at four PEEP levels (5, 10, 15, 20 cm H(2)O) followed by HFOV at corresponding transpulmonary pressures, first with normal ICP and then with AICH. Systemic and pulmonary hemodynamics, cardiac function, cerebral perfusion pressure (CPP), cerebral blood flow (CBF), cerebral tissue oxygenation, and blood gases were measured after 10 min at each level. Transpulmonary pressures (TPP) were calculated at each PEEP level. The measurements were repeated with HFOV using continuous distending pressures (CDP) set at TPP plus 5 cm H(2)O for the corresponding PEEP level. Both measurement series were repeated after intracranial pressure (ICP) had been raised to 30-40 cm H(2)O with an intracranial balloon catheter. Cardiac output, stroke volume, MAP, CPP, and CBF were significantly higher during HFOV at normal ICP. Systemic and cerebral hemodynamics was significantly altered by AICH, but there were no differences attributable to the ventilatory mode. HFOV is associated with less hemodynamic compromise than VCV, even when using small tidal volumes and low mean airway pressures. It does not impair cerebral perfusion or tissue oxygenation in animals with AICH, and could, therefore, be a useful ventilatory strategy to prevent lung failure in patients with traumatic brain injury.

High-Frequency Oscillation as a Rescue Strategy for Brain-Injured Adult Patients with Acute Lung Injury and Acute Respiratory Distress Syndrome

Acute lung injury and acute respiratory distress syndrome (ARDS) occur frequently in brain-injured patients. Single organ dysfunction ventilator strategies result in a conflict between lung protective ventilation and the prevention of secondary neurological insult(s). The objectives of this study were to determine if clinical and physiological benefits of high-frequency oscillatory ventilation (HFOV) exist compared to conventional ventilation and to determine what data there are on the effects of HFOV on cerebral perfusion pressure and intracranial pressure. Systematic review was designed. An optimally sensitive search strategy was used that included; OVID MEDLINE, OVID EMBASE, Cochrane Clinical Trials Register, and hand searching of references of retrieved articles and proceedings of meetings. Study selection includes published randomized controlled trials comparing HFOV with conventional ventilation in adults with ARDS and observational studies of the use of HFOV in adults with ARDS and traumatic brain injury (TBI). Both authors reviewed all trials. A data extraction form was used. In adults with ARDS no mortality benefit has been shown with HFOV, oxygenation improves, arterial partial pressure of CO(2) may increase and there is no change in mean arterial blood pressure. There are few data describing HFOV in adults with TBI. In the small, low quality, studies that have been reported there have not been uncontrollable changes in intracranial pressure. HFOV has not been shown to have any mortality benefit in adults with ARDS. There are insufficient data to clarify the role, or safety, of HFOV in adults with TBI and concurrent ARDS.

Effects of High-Frequency Oscillatory Ventilation on Oleic Acid-Induced Lung Injury in Sheep

High-frequency oscillatory ventilation (HFOV) is a possible mechanical method for open lung strategies. The aim of this study was to examine whether HFOV has a beneficial effect on oleic acid-induced lung injury, with emphasis on changes in extravascular lung water. Thirteen anesthetized sheep prepared with a lung lymph fistula and vascular catheters for monitoring were randomly allocated to two experimental groups. In experiment 1, sheep (n = 6) were ventilated using conventional mechanical ventilation [CMV; 10 ml/kg of tidal volume, 70% oxygen, and positive end-expiratory pressure (PEEP) of 6 cmH(2)O after oleic acid administration (0.08 ml/kg)]. In experiment 2, sheep (n=7) were ventilated using HFOV (frequency=15 Hz, stroke volume=120 ml, mean airway pressure=15 cmH(2)O) after administration of the same dose of oleic acid as in experiment 1. Observation was continued for 4 h after oleic acid administration, then bronchoalveolar lavage (BAL) was performed and the lung wet-to-dry weight ratio was determined. Compared with CMV, HFOV significantly improved the deteriorated oxygenation during the late phase (2-4 h) of oleic acid-induced lung injury without any deterioration effects on pulmonary or systemic hemodynamics. HFOV showed significantly reduced lung lymph protein clearance, which paralleled significant decreases in wet-to-dry ratios and neutrophil counts in BAL fluid in the HFOV group. These findings suggest that HFOV could contribute to decreased lung lymph filtration in pulmonary microcirculation and improved oxygenation following oleic acid-induced lung injury in sheep.

High-Frequency Oscillatory Ventilation, Partial Liquid Ventilation, or Conventional Mechanical Ventilation in NewbornPiglets with Saline Lavage-Induced Acute Lung Injury

It has been reported that, in diseased lungs, either partial liquid ventilation (PLV) or high-frequency oscillatory ventilation (HFOV) can improve oxygenation better and with less lung injury than conventional mechanical ventilation (CMV). This study was intended as a preclinical comparison between the effects of HFOV, PLV and CMV on gas exchange, lung mechanics and histology. Fifteen anesthetized newborn piglets, with respiratory insufficiency due to repeated saline lung lavage, were allocated to either a PLV, HFOV or CMV (n = 5 each) strategy, and treated for 4 h. Within 30 min of commencing therapy, PLV, HFOV, and CMV improved arterial Po₂ (Pa,o₂), alveoloarterial oxygen gradient (P(A-a),o₂), oxygenation index (OI), venous admixture (va), and arterial Pco₂ (Pa,co₂). After 4 h, oxygenation parameters (Pa,o₂, P(A-a),o₂, OI and venous admixture) were significantly better in the HFOV group than in the PLV group; the CMV group showed a higher Pa,o₂ and lower OI than the PLV group. Gas exchange at the end of the experiment was not different from baseline in the HFOV and CMV groups. Lung histology and morphometry were performed after perfusion-fixation at endotracheal deflation pressure corresponding to mean airway pressure at the end of the experiment. Lung injury score and mean linear intercept were not different between the three treatment groups. We conclude that in this model, gas exchange improved significantly in all three ventilation strategies. Indices of oxygenation improved less during PLV. The saline lavage-induced acute lung injury model used as in this study, is less stable than previously thought. The final lung injury is not influenced by the ventilation strategy. We speculate that the impaired gas exchange during PLV is an expression of diffusion limitation and ventilation-perfusion mismatch in a recovering lung.

High frequency oscillatory ventilation attenuates the activation of alveolar macrophages and neutrophils in lung injury.

BACKGROUND: Recent investigations have shown that leukocyte activation is involved in the pathogenesis of ventilator-associated lung injury. This study was designed to investigate whether the inflammatory responses and deterioration of oxygenation in ventilator-associated lung injury are attenuated by high-frequency oscillatory ventilation (HFO). We analyzed the effects of HFO compared with conventional mechanical ventilation (CMV) on the activation of pulmonary macrophages and neutrophils in 10 female rabbits. RESULTS: After surfactant depletion, the rabbits were ventilated by CMV or HFO at the same mean airway pressure. Surfactant-depletion followed by 4 h mechanical ventilation hindered pulmonary oxygenation in both groups. Impairment of oxygenation was less severe in the HFO group than in the CMV group. In the HFO group the infiltration of granulocytes into alveolar spaces occurred more readily than in the CMV group. Compared with CMV, HFO resulted in greater attenuation of beta2-integrin expression, not only on granulocytes, but also on macrophages. CONCLUSIONS: In the surfactant-depleted lung, the activation of leukocytes was attenuated by HFO. Reduced inflammatory response correlated with decreased impairment of oxygenation. HFO may reduce lung injury via the attenuation of pulmonary inflammation.

Effects of high-frequency oscillatory ventilation on vagal and phrenic nerve activities.

This study was undertaken to define the mechanism for the respiratory inhibition observed during high-frequency oscillatory ventilation (HFOV). The effects of HFOV on the activities of single units in the vagus (Vna) and phrenic nerves (Pna) were examined in pentobarbital-anesthetized dogs. The animals were either ventilated by intermittent positive-pressure ventilation (IPPV) with and without positive end-expiratory pressure (PEEP), or by HFOV at a frequency of 25 Hz and pump displacement volume of 3 ml/kg. In 13 vagal units the Vna was much higher during HFOV than during IPPV or airway occlusion at a matched airway pressure. Ten units in the phrenic nerves were examined, and Pna (expressed as bursts/min) was attenuated by HFOV in all of them. In four of them, the effect of cooling the vagi to 8-10 degrees C on Pna was examined, and it was found that HFOV failed to alter the Pna. We conclude that 1) HFOV stimulates the pulmonary vagal afferent fibers continuously and to a degree greater than that due to static lung inflation and increased airway pressure and 2) the increased vagal activity during HFOV probably causes phrenic nerve activity inhibition.