"Every breath you take": evaluating sound levels and acoustic characteristics of various neonatal respiratory support and ventilation modalities

Background

Early sensory experiences have a significant impact on the later life of preterm infants. The NICU soundscape is profoundly influenced by various modalities of respiratory support or ventilation, which are often mandatory early in the care. The incubator, believed to shield from external noise, is less effective against noise originating inside. The objective of this study was to evaluate the sound levels and characteristics of frequently used respiratory support and ventilation modalities, taking into consideration the developing auditory system of premature infants.

Methods

To evaluate sound dynamics inside and outside an incubator during respiratory support/ventilation, experimental recordings were conducted at the Center for Pediatric Simulation Training of the Medical University Vienna. The ventilator used was a FABIAN HFOI®.

Results

Jet CPAP (Continuous positive airway pressure), whether administered via mask or prongs, generates significantly higher sound levels compared to High-flow nasal cannula (HFNC) and to High-frequency oscillatory ventilation (HFOV) delivered through an endotracheal tube. Upon evaluating the sound spectrum of jet CPAP support, a spectral peak is observed within the frequency range of 4 to 8 kHz. Notably, this frequency band aligns with the range where the hearing threshold of preterm infants is at its most sensitive.

Conclusion

Non-invasive HFNC and invasive HFOV generate lower sound levels compared to those produced by jet CPAP systems delivered via masks or prongs. Moreover, HFNC and HFOV show a reduced acoustic presence within the frequency range where the preterm infant's hearing is highly sensitive. Therefore, it is reasonable to speculate that the potential for auditory impairment might be more pronounced in preterm infants who require prolonged use of jet CPAP therapy during their time in the incubator.

Humidity during high-frequency oscillatory ventilation compared to intermittent positive pressure ventilation in extremely preterm neonates: An in vitro and in vivo observational study

BACKGROUND

Inappropriate humidification of inspired gas during mechanical ventilation can impair lung development in extremely low birthweight (ELBW) infants. Humidification depends on multiple factors, such as the heater-humidifier device used, type of ventilation, and environmental factors. Few studies have examined inspired gas humidification in these infants, especially during high-frequency oscillatory ventilation (HFOV). Our objective was to compare humidity during HFOV and intermittent positive pressure ventilation (IPPV), in vitro and in vivo.

METHODS

In vitro and in vivo studies used the same ventilator during both HFOV and IPPV. The bench study used a neonatal test lung and two heater-humidifiers with their specific circuits; the in vivo study prospectively included preterm infants born before 28 weeks of gestation.

RESULTS

On bench testing, mean absolute (AH) and relative (RH) humidity values were significantly lower during HFOV than IPPV (RH = 79.4 ± 8.1% vs. 89.0 ± 6.2%, p < 0.001). Regardless of the ventilatory mode, mean RH significantly differed between the two heater-humidifiers (89.6 ± 6.7% vs 78.7 ± 6.8%, p = 0.003). The in vivo study included 10 neonates (mean ± SD gestational age: 25.7 ± 0.9 weeks and birthweight: 624.4 ± 96.1 g). Mean RH during HFOV was significantly lower than during IPPV (74.6 ± 5.7% vs. 83.0 ± 6.7%, p = 0.004).

CONCLUSION

RH was significantly lower during HFOV than IPPV, both in vitro and in vivo. The type of heater-humidifier also influenced humidification. More systematic measurements of humidity of inspired gas, especially during HFOV, should be considered to optimize humidification and consequently lung protection in ELBW infants.

Oscillation Transmission of Modern High-Frequency Neonatal Ventilators Under Different Lung Mechanics Conditions

BACKGROUND

High-frequency oscillatory ventilation (HFOV) is widely used in neonatal critical care, and several modern ventilators using different technologies are available to provide HFOV. These devices have different technical characteristics that might interact with patient lung mechanics to influence the effectiveness of ventilation. To verify this, we studied the oscillation transmission of 5 neonatal oscillators in a lung model mimicking the mechanical patterns commonly observed in neonatal practice.

METHODS

This was a benchtop, in vitro, physiological, pragmatic study using a model mimicking airways and lung of a 1-kg preterm neonate and the following patterns: normal (compliance: 1.0 mL/cm H₂O, resistance: 50 cm H₂O/L/s), restrictive (compliance: 0.3 mL/cm H₂O, resistance: 50 cm H₂O/L/s), and mixed mechanics (compliance: 0.3 mL/cm H₂O, resistance: 250 cm H₂O/L/s). Several permutations of HFOV parameters (variable mean airway pressure or amplitude or frequency protocols) were tested. Oscillations were measured with a dedicated pressure transducer validated for use during HFOV, and oscillatory pressure ratio (OPR) was calculated to estimate the oscillation transmission.

RESULTS

Overall OPR (calculated on all experiments) was significantly different between ventilators and the mechanical patterns (both P < .001). Different ventilators and patterns accounted for 35.6% and 20.6% of the variation in oscillation transmission, respectively. Sub-analyses per changing amplitude or frequency protocols and multivariate regressions showed that VN500 (standardized β coefficient [St.β]: 0.548, P < .001) and Fabian HFO (St.β: 0.421, P < .001; adjusted R²: 0.615) provided the best oscillation transmission. Fabian HFO also delivered oscillations with the lowest variability when increasing amplitude.

CONCLUSIONS

In an experimental setting mimicking typical neonatal lung disorders, the oscillation transmission was more dependent on the ventilator model than on the mechanical lung conditions at equal HFOV parameters. Fabian HFO and VN500 provided better oscillation transmission overall, and when increasing amplitude, Fabian HFO delivered oscillations with the lowest variability.

Ultra-slim flexible bronchoscopy-guided topical hemostatic drugs administration for the management of life-threatening refractory pulmonary hemorrhage in a preterm infant: Case report

Pulmonary hemorrhage (PH) is a rare acute catastrophic event with high mortality among neonates, especially preterm infants. Primary treatments included pulmonary surfactant, high-frequency oscillatory ventilation, epinephrine, coagulopathy management, and intermittent positive pressure ventilation. However, there are still challenges in diagnosing and treating refractory or focal pulmonary hemorrhages. Ultra-slim bronchoscopy has been widely used in the field of critically ill children and is increasingly being done in neonates with critical respiratory disease in recent years. In this study, we report a case with refractory pulmonary hemorrhage in premature infants, which was finally diagnosed as localized hemorrhage in the upper left lobe and cured by ultra-slim bronchoscopy-guided topical hemostatic drug administration. Bronchoscopy is an optional, safe, and practicable technique for early diagnosis and direct injection therapy of neonatal PH in managing life-threatening PH.

Evaluation of High-Frequency Oscillatory Ventilation as a Rescue Strategy in Respiratory Failure

BACKGROUND

The use of high-frequency oscillatory ventilation (HFOV) is backed by sound physiologic rationale, but clinical data on the elective use of HFOV have been largely disappointing. Nonetheless, HFOV is still occasionally used as a rescue mode in patients with severe hypoxemia. The evidence that supports this practice is sparse.

METHODS

This was a retrospective single-center analysis that involved subjects admitted to the medical ICU at Cleveland Clinic, Cleveland, Ohio. We included all adult patients (ages > 18 y) who received rescue HFOV between January 1, 2010, and December 31, 2018, and analyzed their clinical outcomes.

RESULTS

A total of 48 subjects were included in the analysis. The most common primary diagnosis was pneumonia (n = 33 [68.8%]), followed by aspiration (n = 6 [12.5%]) and diffuse alveolar hemorrhage (n = 2 [4.2%]). Switching to HFOV improved oxygenation but also increased vasopressor requirements at 3 h. The mortality rate of the study population was 92% (44/48).

CONCLUSIONS

Our study did not support utilization of HFOV as a "last-ditch" rescue measure in subjects with respiratory failure. The delayed timing of HFOV initiation and its detrimental hemodynamic effects are among the potential reasons for the high mortality rate.

Efficacy comparison of high-frequency oscillatory ventilation with continuous nasal positive airway pressure in neonatal respiratory distress syndrome treatment

OBJECTIVES

To compare the treatment efficacy of high-frequency oscillatory ventilation (HFOV) with nasal continuous positive airway pressure (NCPAP) in the treatment of neonatal respiratory distress syndrome (NRDS) and its effect on the expression of high-mobility group protein B1 (HMGB1).

METHODS

A total of 180 infants with NRDS admitted to our hospital were included and randomly assigned into the HFOV group (receiving conventional therapy and HFOV), the NCPAP group (receiving conventional therapy and NCPAP), and the conventional group (receiving conventional therapy). Qi and blood indicators, heart rate, respiratory frequency, PCO₂, and PaO₂ were observed and recorded before and after treatment, together with complications after treatment. ELISA was performed for HMGB1 Results: A distinctly lower partial pressure of carbon dioxide (PCO₂) but higher arterial partial pressure of oxygen (PaO₂) was observed in the HFOV and NCPAP groups than in the conventional group (P < 0.05), whereas infants in the HFOV group exhibited slight differences in these two indicators from their counterparts in the NCPAP group (P > 0.05). The serum HMGB1 levels in both groups were significantly higher than those in the conventional group (P < 0.05).

DISCUSSION

Both HFOV and NCPAP are feasible in the treatment of NRDS and may play a role in the inhibition of HMGB1.

Hemodynamic effects of high-frequency oscillatory ventilation in preterm neonates with respiratory distress syndrome

BACKGROUND

High-frequency oscillatory ventilation (HFOV) can have negative hemodynamic effects in neonates. We aimed to assess systemic, cerebral, and cardiac hemodynamic changes in preterm neonates with respiratory distress syndrome (RDS) on HFOV.

METHODS

This observational study was conducted from June 2017 until May 2019 on 100 preterm neonates with RDS that needed switching from conventional mechanical ventilation to HFOV. Initial and Follow up capillary blood gas, echocardiographic examination, cranial ultrasound, and Doppler study of cerebral, celiac, superior mesenteric, and renal arteries using resistive index (RI) were performed before, 24 h, and 72 h after the use of HFOV.

RESULTS

There was no statistically significant difference as regards cardiac function, heart rate, or intraventricular hemorrhage on follow up measurements. However blood pressure, left ventricular dimensions, and volumes statistically increased after HFOV. There was a statistically significant decrease in the pulmonary artery systolic pressure after the use of HFOV. After the use of HFOV, there was a statistically significant increase in the superior vena cava flow and left ventricular output while right ventricular output values initially increased then slightly decreased but still higher than the initial values. RI of cerebral, superior mesenteric, celiac, and renal arteries significantly decreased on follow up measurements which reflected increased blood flow in these arteries.

CONCLUSION

HFOV had no negative effect on the cerebral, systemic, or cardiac hemodynamics when applied at optimum MAP. Therefore, concerns about negative hemodynamic effects of HFOV should not discourage the use of HFOV when deemed clinically indicated provided the use of optimum MAP.

HFOV vs CMV for neonates with moderate-to-severe perinatal onset acute respiratory distress syndrome (NARDS): a propensity score analysis

This study aimed to evaluate whether high-frequency oscillatory ventilation (HFOV) could reduce mortality and the incidence of bronchopulmonary dysplasia (BPD) of perinatal-onset neonatal acute respiratory distress syndrome (NARDS) compared with conventional mechanical ventilation (CMV). Medical records were collected and retrospectively analyzed. Among the 700 neonates with NARDS who needed invasive ventilation, 501 (71.6%) received CMV, while 199 (28.4%) received HFOV. One-to-one propensity score matching (127:127) was used to match the baseline characteristics of patients who received CMV and HFOV. The results showed that birth weight and oxygenation index (OI) were independently associated with mortality in the multivariate logistic regression. No significant differences were observed in mortality or the incidence of BPD between the two groups. The incidence of intraventricular hemorrhage (IVH) and ventilation-free days were significantly lower in the HFOV group than in the CMV group (3.9 vs 11.80%, p=0.02; 15.226 vs 20.967 days, p=0.01). There were no significant differences between the two groups regarding other secondary outcomes.Conclusion: HFOV was associated with a decreased incidence of IVH in infants with NARDS compared with CMV. However, there were significantly more VFDs in the CMV group than in the HFOV group, and HFOV did not appear to be superior to CMV in decreasing the mortality and incidence of BPD in infants with NARDS. What is Known: • The diagnostic criteria of neonatal acute respiratory distress syndrome (Montreux criteria) were established in 2017. • To date, studies comparing high-frequency oscillatory ventilation and conventional mechanical ventilation in the treatment of neonatal acute respiratory distress syndrome are insufficient. What is New: • High-frequency oscillatory ventilation did not appear to be superior to conventional mechanical ventilation in decreasing the mortality and incidence of bronchopulmonary dysplasia in infants with moderate-to-severe perinatal-onset neonatal acute respiratory distress syndrome. • High-frequency oscillatory ventilation was associated with a decreased incidence of intraventricular hemorrhage in infants with moderate-to-severe perinatal-onset acute respiratory distress syndrome compared with conventional mechanical ventilation.

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

OBJECTIVE

To 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).

DESIGN

Observational study.

SETTING

Tertiary neonatal intensive care unit.

PATIENTS

Twenty-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.

INTERVENTIONS

All 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 MEASURES

Variations and fluctuations of delivered high-frequency tidal volume (VT_hf), 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.

RESULTS

There were no significant differences in the two groups at starting ventilation with or without VG. The mean applied VT_hf 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 VT_hf/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).

CONCLUSION

HFOV + VG maintains pCO₂ levels within target range and reduces VT_hf delivered variations more consistently than HFOV alone after surfactant administration.

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

BACKGROUND

Titration of the continuous distending pressure during a staircase incremental-decremental pressure lung volume optimization maneuver in children on high-frequency oscillatory ventilation is traditionally driven by oxygenation and hemodynamic responses, although validity of these metrics has not been confirmed.

METHODS

Respiratory inductance plethysmography values were used construct pressure-volume loops during the lung volume optimization maneuver. The maneuver outcome was evaluated by three independent investigators and labeled positive if there was an increase in respiratory inductance plethysmography values at the end of the incremental phase. Metrics for oxygenation (SpO₂, FiO₂), proximal pressure amplitude, tidal volume and transcutaneous measured pCO₂ (p_tcCO₂) obtained during the incremental phase were compared between outcome maneuvers labeled positive and negative to calculate sensitivity, specificity, and the area under the receiver operating characteristic curve. Ventilation efficacy was assessed during and after the maneuver by measuring arterial pH and PaCO₂. Hemodynamic responses during and after the maneuver were quantified by analyzing heart rate, mean arterial blood pressure and arterial lactate.

RESULTS

41/54 patients (75.9%) had a positive maneuver albeit that changes in respiratory inductance plethysmography values were very heterogeneous. During the incremental phase of the maneuver, metrics for oxygenation and tidal volume showed good sensitivity (> 80%) but poor sensitivity. The sensitivity of the SpO₂/FiO₂ ratio increased to 92.7% one hour after the maneuver. The proximal pressure amplitude showed poor sensitivity during the maneuver, whereas tidal volume showed good sensitivity but poor specificity. PaCO₂ decreased and pH increased in patients with a positive and negative maneuver outcome. No new barotrauma or hemodynamic instability (increase in age-adjusted heart rate, decrease in age-adjusted mean arterial blood pressure or lactate > 2.0 mmol/L) occurred as a result of the maneuver.

CONCLUSIONS

Absence of improvements in oxygenation during a lung volume optimization maneuver did not indicate that there were no increases in lung volume quantified using respiratory inductance plethysmography. Increases in SpO₂/FiO₂ one hour after the maneuver may suggest ongoing lung volume recruitment. Ventilation was not impaired and there was no new barotrauma or hemodynamic instability. The heterogeneous responses in lung volume changes underscore the need for monitoring tools during high-frequency oscillatory ventilation.

Influenced CD cells and ICAM-1 by pulmonary surfactant combined with high-frequency oscillatory ventilation and its effects on immune function in children with neonatal respiratory distress syndrome

This study aimed to explore the clinical efficacy of pulmonary surfactant combined with high-frequency oscillatory ventilation (HFOV) on neonatal respiratory distress syndrome (NRDS) and its influence on immune function in children. Children admitted to our hospital from March 2017 to March 2019 who received HFOV combined with pulmonary surfactant therapy as a research group. Sixty-two children received conventional nasal continuous positive pressure combined with pulmonary surfactant therapy as a control group. Clinical efficacy, blood gas and immune function of patients were compared between the two groups. The clinical efficacy of the research group was better than that of the control group (P&lt; 0.050). PaO2 and PaO2/FiO2 were both higher after treatment (P&lt; 0.050). CD3+ and NK cells in the research group were higher than those in the control group, while CD8+ cells and ICAM-1 were lower than those in the control group (P&lt; 0.050). CD3+, CD4+ and NK cells decreased in both groups after treatment, while CD8+ cells and ICAM-1 increased (P&lt; 0.050). HFOV combined with pulmonary surfactant has significant clinical efficacy and high safety on NRDS, and has a certain protective effect on children's immune function. Hence, it is worthy of being the first choice for the clinical treatment of NRDS in the future.

Volume Guarantee High-Frequency Oscillatory Ventilation in Preterm Infants With RDS: Tidal Volume and DCO2 Levels for Optimal Ventilation Using Open-Lung Strategies

High frequency oscillatory ventilation with volume-guarantee (HFOV-VG) is a promising lung protective ventilator mode for the treatment of respiratory failure in newborns. However, indicators of optimal ventilation during HFOV-VG mode are not identified yet. In this study, we aimed to evaluate optimal high-frequency tidal volume (VThf) and the dissociation coefficient of CO₂ (DCO₂) levels to achieve normocapnia during HFOV-VG after lung recruitment in very low birthweight infants with respiratory distress syndrome (RDS). Preterm babies under the 32nd postmenstrual week with severe RDS that received HFOV-VG using open-lung strategy between January 2014 and January 2019 were retrospectively evaluated. All included patients were treated with the Dräger Babylog VN500 ventilator in the HFOV-VG mode. In total, 53 infants with a mean gestational age of 26.8 ± 2.3 weeks were evaluated. HFOV mean optimal airway pressure (MAPhf) level after lung recruitment was found to be 10.2 ± 1.7 mbar. Overall, the mean applied VThf per kg was 1.64 ± 0.25 mL/kg in the study sample. To provide normocapnia, the mean VThf was 1.61 ± 0.25 mL/kg and the mean DCO₂corr was 29.84 ± 7.88 [mL/kg]²/s. No significant correlation was found between pCO₂ levels with VThf (per kg) or DCO₂corr levels. VThf levels to maintain normocarbia were significantly lower with 12 Hz frequency compared to 10 Hz frequency (1.50 ± 0.24 vs. 1.65 ± 0.25 mL/ kg, p < 0.001, respectively). A weak but significant positive correlation was found between mean airway pressure (MAPhf) and VThf levels. To our knowledge, this is the largest study to evaluate the optimal HFOV-VG settings in premature infants with RDS, using the open-lung strategy. According to the results, a specific set of numbers could not be recommended to achieve normocarbia. Following the trend of each patient and small adjustments according to the closely monitored pCO₂ levels seems logical.

Miliary tuberculosis leading to acute respiratory distress syndrome: Clinical experience in pediatric intensive care

Acute respiratory distress syndrome (ARDS) represents a rare complication of miliary tuberculosis (TB) in the adult setting, and it is even less common in the pediatric population. The presence of comorbidities and the possibility of a delayed diagnosis may further impair the clinical prognosis of critically ill patients with disseminated TB and acute respiratory failure. In this report, we present a case series of five pediatric patients with miliary TB and ARDS, where rescue and multimodal respiratory support strategies have been applied with a favorable outcome in more than half of them. The burden of miliary TB over time on a general pediatric intensive care unit-including two ARDS patients-is also illustrated.

High-frequency oscillatory ventilation guided by transpulmonary pressure in acute respiratory syndrome: an experimental study in pigs

BACKGROUND

Recent clinical studies have not shown an overall benefit of high-frequency oscillatory ventilation (HFOV), possibly due to injurious or non-individualized HFOV settings. We compared conventional HFOV (HFOV_con) settings with HFOV settings based on mean transpulmonary pressures (P_Lmean) in an animal model of experimental acute respiratory distress syndrome (ARDS).

METHODS

ARDS was induced in eight pigs by intrabronchial installation of hydrochloric acid (0.1 N, pH 1.1; 2.5 ml/kg body weight). The animals were initially ventilated in volume-controlled mode with low tidal volumes (6 ml kg^- 1) at three positive end-expiratory pressure (PEEP) levels (5, 10, 20 cmH₂O) followed by HFOV_con and then HFOV P_Lmean each at PEEP 10 and 20. The continuous distending pressure (CDP) during HFOV_con was set at mean airway pressure plus 5 cmH₂O. For HFOV P_Lmean it was set at mean P_L plus 5 cmH₂O. Baseline measurements were obtained before and after induction of ARDS under volume controlled ventilation with PEEP 5. The same measurements and computer tomography of the thorax were then performed under all ventilatory regimens at PEEP 10 and 20.

RESULTS

Cardiac output, stroke volume, mean arterial pressure and intrathoracic blood volume index were significantly higher during HFOV P_Lmean than during HFOV_con at PEEP 20. Lung density, total lung volume, and normally and poorly aerated lung areas were significantly greater during HFOV_con, while there was less over-aerated lung tissue in HFOV P_Lmean. The groups did not differ in oxygenation or extravascular lung water index.

CONCLUSION

HFOV P_Lmean is associated with less hemodynamic compromise and less pulmonary overdistension than HFOV_con. Despite the increase in non-ventilated lung areas, oxygenation improved with both regimens. An individualized approach with HFOV settings based on transpulmonary pressure could be a useful ventilatory strategy in patients with ARDS. Providing alveolar stabilization with HFOV while avoiding harmful distending pressures and pulmonary overdistension might be a key in the context of ventilator-induced lung injury.

Extubation from high-frequency oscillatory ventilation in extremely low birth weight infants: a prospective observational study

OBJECTIVE

To evaluate if weaning from high-frequency oscillatory ventilation (HFOV) directly to a non-invasive mode of respiratory support is feasible and results in successful extubation in extremely low birth weight (ELBW) infants.

DESIGN

Prospective observational study.

SETTING

Tertiary neonatal intensive care unit.

PATIENTS

One hundred and eight ELBW infants of 26.2±1.4 weeks of gestational age (GA) directly extubated from HFOV.

INTERVENTIONS

All infants were managed with elective HFOV and received surfactant after a recruitment HFOV manoeuvre. Extubation was attempted at mean airways pressure (MAP) ≤6 cm H₂O with FiO₂ ≤0.25. After extubation, all infants were supported by nasal continuous positive airway pressure (6-8 cm H₂O).

MAIN OUTCOME MEASURES

Extubation failure (clinical deterioration requiring reintubation) was defined as shorter than 7 days.

RESULTS

Ninety patients (83%) were successfully extubated and 18 (17%) required reintubation. No significant differences were found between the two groups in terms of birth weight, day of life and weight at the time of extubation. Multivariable analysis showed that GA (OR 1.71; 95% CI 1.04, 2.08) and higher MAP prior to surfactant (OR 1.51; 95% CI 1.06, 2.15) were associated with successful extubation.

CONCLUSIONS

In ELBW infants, direct extubation from HFOV at MAP ≤6 cm H₂O with FiO₂ ≤0.25 is feasible. Our extubation success rate (83%) is higher than conventional mechanical ventilation in this very vulnerable class of infants.

Management of pneumothorax in hemodynamically stable preterm infants using high frequency oscillatory ventilation: report of five cases

Background

Despite an increased use of non-invasive ventilatory strategies and gentle ventilation, pneumothorax remains a common complication in preterm infants. The ventilator management of infants with air leaks remains challenging in terms of both prevention and treatment. Recently the safety and efficacy of expectant management avoiding chest tube drainage to treat large air leak in preterm infants hemodynamically stable has been reported.

Case presentation

In the present study, we report five cases of preterm infants with birth weight ≤ 1250 g affected by respiratory distress syndrome and treated with nasal continuous positive airway pressure as first intention. They were intubated for worsening of respiratory distress with increasing oxygen requirement and concomitant increase of respiratory rate and P_CO2 values due to occurrence of pneumothorax, and they were successfully treated using high-frequency oscillatory ventilation without chest tube insertion.

Conclusion

In our experience high-frequency oscillatory ventilation provided a conservative management of a significant pneumothorax in preterm newborns hemodynamically stable and requiring mechanical ventilation. This approach allowed us to avoid the increasing of air leak and the insertion of chest tube drainage and all the subsequent associated risks.

A translational cellular model to study the impact of high-frequency oscillatory ventilation on human epithelial cell function

High-frequency oscillatory ventilation (HFOV) has been proposed as gentle ventilation strategy to prevent lung injury in the preterm infant. High-frequency jet ventilation leads to dimensional and mechanical airway deformation in animal airway models, which is consistent with translational studies demonstrating the impact of oxygen and biophysical stresses on normal airway cellular function. There is an overall paucity of clinical and cellular data on the impact of HFOV on the conducting airway. We developed an innovative method to test the impact of the clinical HFO Ventilator (SensorMedics 3100A) on human epithelial cell function. In this translational model, we were able to study the differential effects of biophysical stress due to HFOV independently and in combination with hyperoxia on a direct cellular level of the conducting airway system. Additionally, we could demonstrate that hyperoxia and pressure by HFOV independently resulted in significant cell dysfunction and inflammation, while the combination of HFOV and hyperoxia had a synergistic effect, resulting in greater cell death.

NEW & NOTEWORTHY

Traditionally, large-animal models are used to analyze the impact of clinical ventilators on lung cellular function. In our dual-chamber model, we interface high-frequency oscillatory ventilation (HFOV) directly with airway cells to study the effects of HFOV independently and combined with hyperoxia. Therefore, it is possible to study the preclinical impact of interventional factors without the high cost of animal models, thus reducing staff, time, as well as animal sparing.

Non-invasive high-frequency oscillatory ventilation in neonates: review of physiology, biology and clinical data

Non-invasive high-frequency oscillatory ventilation (NHFOV) consists of the application of a bias flow generating a continuous distending positive pressure with superimposed oscillations, which have constant frequency and active expiratory phase. NHFOV matches together the advantages of high-frequency ventilation (no need for synchronisation, high efficacy in removing CO₂) and nasal continuous positive airway pressure (CPAP) (non-invasive interface, increase in functional residual capacity allowing oxygenation to improve). There is enough clinical expertise demonstrating that NHFOV may be tried in some selected cases, in whom CPAP or conventional non-invasive ventilation have failed. Nonetheless, there are no clear data about its clinical usefulness and there is a need for randomised controlled studies. Our purpose is to review the physiology and biological effects of NHFOV, to present the current clinical evidence on its use, to provide some guiding principles to clinicians and suggest directions for further research.

Efficacy of a new technique - INtubate-RECruit-SURfactant-Extubate - "IN-REC-SUR-E" - in preterm neonates with respiratory distress syndrome: study protocol for a randomized controlled trial

Background

Although beneficial in clinical practice, the INtubate-SURfactant-Extubate (IN-SUR-E) method is not successful in all preterm neonates with respiratory distress syndrome, with a reported failure rate ranging from 19 to 69 %. One of the possible mechanisms responsible for the unsuccessful IN-SUR-E method, requiring subsequent re-intubation and mechanical ventilation, is the inability of the preterm lung to achieve and maintain an “optimal” functional residual capacity. The importance of lung recruitment before surfactant administration has been demonstrated in animal studies showing that recruitment leads to a more homogeneous surfactant distribution within the lungs. Therefore, the aim of this study is to compare the application of a recruitment maneuver using the high-frequency oscillatory ventilation (HFOV) modality just before the surfactant administration followed by rapid extubation (INtubate-RECruit-SURfactant-Extubate: IN-REC-SUR-E) with IN-SUR-E alone in spontaneously breathing preterm infants requiring nasal continuous positive airway pressure (nCPAP) as initial respiratory support and reaching pre-defined CPAP failure criteria.

Methods/design

In this study, 206 spontaneously breathing infants born at 24⁺⁰–27⁺⁶ weeks’ gestation and failing nCPAP during the first 24 h of life, will be randomized to receive an HFOV recruitment maneuver (IN-REC-SUR-E) or no recruitment maneuver (IN-SUR-E) just prior to surfactant administration followed by prompt extubation. The primary outcome is the need for mechanical ventilation within the first 3 days of life. Infants in both groups will be considered to have reached the primary outcome when they are not extubated within 30 min after surfactant administration or when they meet the nCPAP failure criteria after extubation.

Discussion

From all available data no definitive evidence exists about a positive effect of recruitment before surfactant instillation, but a rationale exists for testing the following hypothesis: a lung recruitment maneuver performed with a step-by-step Continuous Distending Pressure increase during High-Frequency Oscillatory Ventilation (and not with a sustained inflation) could have a positive effects in terms of improved surfactant distribution and consequent its major efficacy in preterm newborns with respiratory distress syndrome. This represents our challenge.

Trial registration

ClinicalTrials.gov identifier: NCT02482766. Registered on 1 June 2015.

Effects of ventilation modalities on near-infrared spectroscopy in surgically corrected CDH infants

BACKGROUND

Near-infrared spectroscopy (NIRS) is a noninvasive technique for monitoring tissue oxygenation and perfusion. The aim of this study was to evaluate cerebral and splanchnic NIRS changes in CDH operated infants enrolled into the VICI trial and therefore randomized for ventilatory modalities.

MATERIALS AND METHODS

CDH newborns enrolled into the VICI trial (Netherlands Trial Register, NTR 1310) were randomized at birth for high-frequency oscillatory ventilation (HFOV) or conventional mechanical ventilation (CMV) according to the trial. Cerebral oxygenation (rSO2C) and splanchnic oxygenation (rSO2S) were obtained by NIRS (INVOS 5100; Somanetics, Troy, MI) before and after surgery. Variations in rSO2C and rSO2S were evaluated. Mann-Whitney test and one-way ANOVA were used as appropriate. p<0.05 was considered significant.

RESULTS

Thirteen VICI trial patients underwent surgical repair between March 2011 and December 2012, and were enrolled in the study. Seven patients were assigned to HFOV and six to CMV group respectively. During surgery, a significant reduction in rSO2C (p=0.0001) and rSO2S (p=0.005) were observed. HFOV patients experienced prolonged reduction in rSO2C value (p=0.003) while rSO2S did not vary between HFOV and CMV (p=0.94).

CONCLUSIONS

Surgical CDH repair was associated with decrease of cerebral and splanchnic oxygenation, regardless of ventilation. Patients ventilated by HFOV need a longer time interval to recovery normal rSO2C values, than those ventilated by CMV. This may be owing to a different impact of HFOV on patients' hemodynamic status with a higher impairment on total venous return and its negative consequences on cardiac output.

Did studies on HFOV fail to improve ARDS survival because they did not decrease VILI? On the potential validity of a physiological concept enounced several decades ago

High frequency oscillatory ventilation (HFOV) has been the subject of extensive physiological research for 30 years and even more so of an intense debate on its potential usefulness in the treatment of acute respiratory distress syndrome (ARDS). This technique has been enthusiastically promoted by some teams until two high-quality randomized clinical trials in adults with ARDS showed that HFOV did not decrease and might have even increased mortality. As a consequence of these results, physiological concepts such as atelectrauma and biotrauma on which ARDS management with HFOV were based should be reexamined. In contrast, the concept of volutrauma, i.e., end-inspiratory overdistension, as the cause for ventilator-induced lung injury might help explain excess mortality during mechanical ventilation of ARDS when inspiratory volumes are too high. This is what might have happened during one of the recent studies on HFOV. Failure of this complex technique must be put in perspective with the dramatic improvement of ARDS prognosis with very simple interventions such as tidal volume reduction, early pharmacological paralysis, and prone positioning which all limited end-inspiratory volume.

Airway Pressure Release Ventilation and High-Frequency Oscillatory Ventilation: Potential Strategies to Treat Severe Hypoxemia and Prevent Ventilator-Induced Lung Injury

Although lifesaving, mechanical ventilation can itself be responsible for damage to lung parenchyma. This ventilator-induced lung injury is especially observed in already injured lungs of patients with ARDS. New ventilatory approaches are needed to safely treat patients with ARDS, and recent studies have suggested the potential utility of open-lung strategies. Airway pressure release ventilation (APRV) and high-frequency oscillatory ventilation (HFOV) are 2 different open-lung strategies that have been proposed to treat refractory hypoxemic respiratory failure while preventing ventilator-induced lung injury. APRV provides increased airway pressure as a potential recruitment mechanism and allows spontaneous breathing, with the potential benefits of decreased sedation, shorter duration of mechanical ventilation, and improvement in cardiac performance. HFOV delivers very small tidal volumes, to prevent volutrauma, at a constant (relatively high) mean airway pressure, thus avoiding atelectrauma. Despite their theoretical benefits, the utility of APRV and HFOV remains unproven and controversial for the routine treatment of ARDS in adult patients. This review is focused on the theoretical and practical aspects of APRV and HFOV, provides an overview of the current evidence, and addresses their possible use in the treatment of ARDS.

Year in review 2014: mechanical ventilation

Mechanical ventilation is an important and ever-evolving component of everyday critical care. Clinicians can struggle to keep up with current literature and descriptions of advancement in a way that they can apply these changes to their bedside patient care. This article serves as a review of important recent findings related to invasive mechanical ventilation and describes their relevance to bedside critical care.

To ventilate, oscillate, or cannulate?

Ventilatory management of acute respiratory distress syndrome has evolved significantly in the last few decades. The aims have shifted from optimal gas transfer without concern for iatrogenic risks to adequate gas transfer while minimizing lung injury. This change in focus, along with improved ventilator and multiorgan system management, has resulted in a significant improvement in patient outcomes. Despite this, a number of patients develop hypoxemic respiratory failure refractory to lung-protective ventilation (LPV). The intensivist then faces the dilemma of either persisting with LPV using adjuncts (neuromuscular blocking agents, prone positioning, recruitment maneuvers, inhaled nitric oxide, inhaled prostacyclin, steroids, and surfactant) or making a transition to rescue therapies such as high-frequency oscillatory ventilation (HFOV) and/or extracorporeal membrane oxygenation (ECMO) when both these modalities are at their disposal. The lack of quality evidence and potential harm reported in recent studies question the use of HFOV as a routine rescue option. Based on current literature, the role for venovenous (VV) ECMO is probably sequential as a salvage therapy to ensure ultraprotective ventilation in selected young patients with potentially reversible respiratory failure who fail LPV despite neuromuscular paralysis and prone ventilation. Given the risk profile and the economic impact, future research should identify the patients who benefit most from VV ECMO. These choices may be further influenced by the emerging novel extracorporeal carbon dioxide removal devices that can compliment LPV. Given the heterogeneity of acute respiratory distress syndrome, each of these modalities may play a role in an individual patient. Future studies comparing LPV, HFOV, and VV ECMO should not only focus on defining the patients who benefit most from each of these therapies but also consider long-term functional outcomes.