Bringing back the old: time to reevaluate the high-frequency ventilation strategy

Impact on cerebral hemodynamics of the use of volume guarantee combined with high frequency oscillatory ventilation in a neonatal animal respiratory distress model

High-frequency oscillatory ventilation (HFOV) is an alternative to conventional mechanical ventilation (CMV). Recently, the use of volume guarantee (VG) combined with HFOV has been suggested as a safe strategy capable of reducing the damage induced by ventilation in immature lungs. However, the possible impact of this new ventilation technique on cerebral hemodynamics is unknown. To evaluate the cerebral hemodynamics effect of HFOV combined with VG in an experimental animal model of neonatal respiratory distress syndrome (RDS) due to surfactant deficiency compared with HFOV and CMV+VG (control group). Eighteen newborn piglets were randomized, before and after the induction of RDS by bronchoalveolar lavage, into 3 mechanical ventilation groups: CMV, HFOV and HFOV with VG. Changes in cerebral oxygen transport and consumption and cerebral blood flow were analyzed by non-invasive regional cerebral oxygen saturation (CrSO2), jugular venous saturation (SjO2), the calculated cerebral oxygen extraction fraction (COEF), the calculated cerebral fractional tissue oxygen extraction (cFTOE) and direct measurement of carotid artery flow. To analyze the temporal evolution of these variables, a mixed-effects linear regression model was constructed. After randomization, the following statistically significant results were found in every group: a drop in carotid artery flow: at a rate of -1.7 mL/kg/min (95% CI: -2.5 to -0.81; p < 0.001), CrSO2: at a rate of -6.2% (95% CI: -7.9 to -4.4; p < 0.001) and SjO2: at a rate of -20% (95% CI: -26 to -15; p < 0.001), accompanied by an increase in COEF: at a rate of 20% (95% CI: 15 to 26; p < 0.001) and cFTOE: at a rate of 0.07 (95% CI: 0.05 to 0.08; p < 0.001) in all groups. No statistically significant differences were found between the HFOV groups.

CONCLUSION

No differences were observed at cerebral hemodynamic between respiratory assistance in HFOV with and without VG, being the latter ventilatory strategy equally safe.

WHAT IS KNOWN

• Preterm have a situation of fragility of cerebral perfusion wich means that any mechanical ventilation strategy can have a significant influence. High-frequency oscillatory ventilation (HFOV) is an alternative to conventional mechanical ventilation (CMV). Recently, the use of volume guarantee (VG) combined with HFOV has been suggested as a safe strategy capable of reducing the damage induced by ventilation in immature lungs. Several studies have compared CMV and HFOV and their effects at hemodynamic level. It is known that the use of high mean airway pressure in HFOV can cause an increase in pulmonary vascular resistance with a decrease in thoracic venous return.

WHAT IS NEW

• The possible impact of VAFO + VG on cerebral hemodynamics is unknown. Due the lack of studies and the existing controversy, we have carried out this research project in an experimental animal model with the aim of evaluating the cerebral hemodynamic repercussion of the use of VG in HFOV compared to the classic strategy without VG.

Lung protection strategy with high-frequency oscillatory ventilation improves respiratory outcomes at two years in preterm respiratory distress syndrome: a before and after, quality improvement study

INTRODUCTION

Bronchopulmonary dysplasia (BPD) remains one of the major challenges of extreme prematurity. High-frequency oscillatory ventilation (HFOV) with volume guarantee (HFOV-VG) can be used as an early-rescue ventilation to protect developing lungs. However, the studies exploring the impact of this ventilatory strategy on neonatal respiratory morbidity are very limited. This study aimed at documenting the improvement in respiratory outcomes in mechanically ventilated preterm newborns, after the implementation of a new mechanical ventilation respiratory bundle.

METHODS

A prospective, quality improvement study was conducted between January 2012 and December 2018 in a third level NICU in Madrid, Spain. Infants born <32 weeks of gestation with severe respiratory distress syndrome (RDS) and requiring invasive mechanical ventilation were included. The intervention consisted of a new ventilation respiratory care bundle, with HFOV as early rescue therapy using low high-frequency tidal volumes (Vthf) and higher frequencies (15-20 Hz). Criteria for HFOV start were impaired oxygenation or ventilation on conventional ventilation, or peak inspiratory pressures >15 cmH₂O. Two cohorts of mechanically ventilated patients were compared, cohort 1 (2012-2013, baseline period) and cohort 2 (2016-2018, after implementation of the new bundle). Clinical outcomes at 36 weeks and 2 years of postmenstrual age were compared between the groups.

RESULTS

A total of 216 patients were included, the median gestational age was 26 weeks (IQR 25-28) and median birth weight was 895 g (IQR 720-1160). There were no significant differences in survival between the groups, but patients with the protective ventilation strategy (cohort 2) had higher survival without BPD 2-3 (OR 2.93, 95%CI 1.41-6.05). At 2 years of postmenstrual age, patients in cohort 2 also had a higher survival free of baseline respiratory treatment and hospital respiratory admissions than the control group (adjusted OR 2.33, 95%CI 1.10-4.93, p=.03). The results did not suggest significant differences in neurologic development.

CONCLUSIONS

In extreme premature related severe respiratory failure, the use of a lung protective HFOV-VG strategy was proven to be a useful quality improvement intervention in our unit, leading to better pulmonary outcomes at 36 weeks and additional improved respiratory prognosis at two years of age.

Lung recruitment in neonatal high-frequency oscillatory ventilation with volume-guarantee

BACKGROUND AND OBJECTIVES

The optimal lung volume strategy during high-frequency oscillatory ventilation (HFOV) is reached by performing recruitment maneuvers, usually guided by the response in oxygenation. In animal models, secondary spontaneous change in oscillation pressure amplitude (ΔPhf) associated with a progressive increase in mean airway pressure during HFOV combined with volume guarantee (HFOV-VG) identifies optimal lung recruitment. The aim of this study was to describe recruitment maneuvers in HFOV-VG and analyze whether changes in ΔPhf might be an early predictor for lung recruitment in newborn infants with severe respiratory failure.

DESIGN AND METHODS

The prospective observational study was done in a tertiary-level neonatology department. Changes in ΔPhf were analyzed during standardized lung recruitment after initiating early rescue HFOV-VG in preterm infants with severe respiratory failure.

RESULTS

Twenty-seven patients were included, with a median gestational age of 24 weeks (interquartile range [IQR]: 23-25). Recruitment maneuvers were performed, median baseline mean airway pressure (mPaw) was 11 cm H₂ O (IQR: 10-13), median critical lung opening mPaw during recruitment was 14 cm H₂ O (IRQ: 12-16), and median optimal mPaw was 12 cm H₂ O (IQR: 10-14, p < 0.01). Recruitment maneuvers were associated with an improvement in oxygenation (FiO₂ : 65.0 vs. 45.0, p < 0.01, SpO2/FiO₂ ratio: 117 vs. 217, p < 0.01). ΔPhf decreased significantly after lung recruitment (mean amplitude: 23.0 vs. 16.0, p < 0.01).

CONCLUSION

In preterm infants with severe respiratory failure, the lung recruitment process can be effectively guided by ΔPhf on HFOV-VG.

High-frequency Ventilation

High-frequency ventilation (HFV) is an alternative to conventional mechanical ventilation, with theoretic benefits of less risk of ventilator lung injury and more effectivity in washout CO₂. Previous clinical studies have not demonstrated advantages of HFV in preterm infants compared with conventional ventilation, so rescue HFV has been used when severe respiratory insufficiency needs aggressive ventilator settings in immature infants. Today it is possible to measure, set directly, and fix tidal volume, which can protect the immature lung from large volumes and fluctuations of the tidal volume. This strategy can be used in preterm infants with respiratory failure needing invasive ventilation.

Target volume-guarantee in high-frequency oscillatory ventilation for preterm respiratory distress syndrome: Low volumes and high frequencies lead to adequate ventilation

BACKGROUND AND OBJECTIVES

Respiratory distress syndrome (RDS) and ventilation-induced lung injury lead to significant morbidity in preterm infants. High-frequency oscillatory ventilation with volume-guarantee (HFOV-VG) has been used as a rescue therapy and might lead to lower rates of death and bronchopulmonary dysplasia, especially when using low tidal volumes and high frequencies. The aim of the study was to define HFOV-VG parameters leading to adequate ventilation in the first 72 h of preterm RDS using a low volume and high-frequency strategy.

DESIGN AND METHODS

Retrospective cohort study in a tertiary-level neonatology unit. Infants <32 weeks with severe respiratory insufficiency needing HFOV-VG were included. Patients were ventilated following a standard mechanical ventilation aiming for low tidal volumes and high frequencies. Clinical data, perinatal characteristics and high-frequency parameters corresponding with adequate ventilation were recorded.

RESULTS

116 patients were included. Median gestational age was 25 weeks (interquartile range [IQR] = 24-27), median birth weight 724 g (IQR = 600-900 g). HFOV-VG was started at 2 h, median high-frequency tidal volume was 1.63 ml/kg (IQR = 1.44-1.84) and median frequency was 16 Hz (IQR = 15-18). Weight-adjusted tidal volumes did not depend on gestational age, antenatal corticosteroids nor chorioamnionitis, and were inversely correlated with frequencies (R ²  = -0.10, p = .001).

CONCLUSION

HFOV-VG can reach adequate ventilation at high frequencies when using adequate volumes, providing a feasible ventilation strategy that might be of help in preterm infants with RDS.

Application of high-frequency oscillation ventilation combined with volume guarantee in infants with acute hypoxic respiratory failure after congenital heart surgery

OBJECTIVE

This study aimed to evaluate the efficacy and safety of high-frequency oscillation ventilation combined with volume guarantee (HFOV-VG) compared with the safety and efficacy of HFOV alone in infants with acute hypoxemic respiratory failure (AHRF) after congenital heart surgery.

METHODS

We retrospectively analyzed the clinical data of 44 infants who were ventilated for AHRF after congenital heart surgery between January 2020 and January 2021. HFOV alone was used in 23 of the 44 infants, whereas HFOV-VG was used in the other 21 infants.

RESULTS

The average frequency tidal volume (VThf) of the HFOV-VG group was lower than that of the HFOV group, and the proportion of VThf exceeding the target range of infants in the HFOV-VG group was also lower (p < .01). In addition, the incidence of hypocapnia and hypercapnia in infants supported with HFOV-VG was significantly lower (p < .01). Furthermore, the duration of invasive ventilation and the median ventilator adjustment per hour in the HFOV-VG group was also lower than that in the HFOV group (p < .01).

CONCLUSIONS

Compared with HFOV alone, HFOV-VG decreases the fluctuation of VThf and the incidence of hypercapnia and hypocapnia. Moreover, it reduces the workload of bedside medical staff. Further studies are needed to confirm the efficacy and safety of HFOV-VG as a routine respiratory support strategy for congenital heart disease during the perioperative period.

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.

DCO2/PaCO2 correlation on high-frequency oscillatory ventilation combined with volume guarantee using increasing frequencies in an animal model

To examine the correlation DCO₂/PaCO₂ on high-frequency oscillatory ventilation (HFOV) combined with volume guarantee (VG) throughout increasing frequencies in two different respiratory conditions, physiological and low compliance. Neonatal animal model was used, before and after a bronchoalveolar lavage (BAL). HFOV combined with VG was used. The frequency was increased from 10 to 20 Hz, and high-frequency tidal volume (VThf) was gradually decreased maintaining a constant DCO₂. Arterial partial pressure of carbon dioxide (PaCO₂) was evaluated after each frequency and VThf change. Six 2-day-old piglets were studied. A linear decrease in PaCO₂ was observed throughout increasing frequencies in both respiratory conditions while maintaining a constant DCO₂, showing a significant difference between the initial PaCO₂ (at 10 Hz) and the PaCO₂ obtained at 18 and 20 Hz. A new DCO₂ equation (corrected DCO₂) was calculated in order to better define the correlation between DCO₂ and the observed PaCO₂.Conclusion: The correlation DCO₂/PaCO₂ throughout increasing frequencies is not linear, showing a greater CO₂ elimination efficiency at higher frequencies, in spite of maintaining a constant DCO₂. So, using frequencies close to the resonant frequency of the respiratory system on HFOV combined with VG, optimizes the efficiency of gas exchange.What is Known: • The efficacy of CO₂removal during high-frequency oscillatory ventilation (HFOV), described as the diffusion coefficient of CO₂(DCO₂) is related to the square of the high-frequency tidal volume (VThf) and the frequency (f), expressed as DCO₂= VThf²× f.What is New: • The correlation between DCO₂and PaCO₂throughout increasing frequencies is not linear, showing a greater CO₂elimination efficiency at higher frequencies. So, using very high frequencies on HFOV combined with volume guarantee optimizes the efficiency of gas exchange allowing to minimize lung injury.

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.

Effect of a new respiratory care bundle on bronchopulmonary dysplasia in preterm neonates

The development of devices that can fix the tidal volume in high-frequency oscillatory ventilation (HFOV) has allowed for a significant improvement in the management of HFOV. At our institution, this had led to the earlier use of HFOV and promoted a change in the treatment strategy involving the use of higher frequencies (above 15 Hz) and lower high-frequency tidal volumes (VThf). The purpose of this observational study was to assess how survival without bronchopulmonary dysplasia grades 2 and 3 (SF-BPD) is influenced by these modifications in the respiratory strategy applied to preterm infants (gestational age < 32 weeks at birth) who required mechanical ventilation (MV) in the first 3 days of life. We compared a baseline period (2012-2013) against a period in which this strategy had been fully implemented (2016-2017). A total of 182 patients were exposed to MV in the first 3 days of life being a higher proportion on HFOV at day 3 in the second period 79.5% (n 35) in 2016-2017 vs 55.4% (n 31) in 2012-2013. After adjusting for perinatal risk factors, the second period is associated with an increased rate of SF-BPD (OR 2.28; CI 95% 1.072-4.878); this effect is more evident in neonates born at a gestational age of less than 29 weeks (OR 4.87; 95% CI 1.9-12.48).Conclusions : The early use of HFOV combined with the use of higher frequencies and very low VT was associated with an increase in the study population's SF-BPD. What is Known: • High-frequency ventilation with volume guarantee improve ventilation stability and has been shown to reduce lung damage in animal models. What is New: • The strategy of an earlier use of high-frequency oscillatory ventilation combined with the use of higher frequencies and lower tidal volume is associated to an increase in survival without bronchopulmonary dysplasia in our population of preterm infants.

Use of very low tidal volumes during high-frequency ventilation reduces ventilator lung injury

The use of volume guarantee (VG) on high-frequency oscillatory ventilation (HFOV) allows to use fixed very low high-frequency tidal volume (VThf), maintaining adequate CO₂ removal while potentially reducing the risk of ventilator-induced lung injury.

OBJECTIVE

To demonstrate that the use of very low VThf can be protective compared with standard VThf on HFOV combined with VG in a neonatal animal model.

STUDY DESIGN

Experimental study in 2-day-old piglets with induced respiratory distress syndrome ventilated with two different HFOV strategies combined with VG (10 Hz with high VThf versus 20 Hz with very low VThf at similar PaCO₂). After 12 h of mechanical ventilation, the pulmonary histologic pattern was analyzed.

RESULTS

We found in the 10 Hz group with the higher VThf compared with the 20 Hz and very low VThf group more evident and more severe histological lesions with inflammatory infiltrate within the alveolar wall and alveolar space, as well as large areas of parenchyma consolidation and areas of alveolar hemorrhage in the more severe cases.

CONCLUSION

The use of very low VThf compared with higher VThf at similar CO₂ removal reduces lung injury in a neonatal animal model of lung injury after prolonged mechanical ventilation with HFOV combined with VG.

Weight-correction of carbon dioxide diffusion coefficient (DCO2 ) reduces its inter-individual variability and improves its correlation with blood carbon dioxide levels in neonates receiving high-frequency oscillatory ventilation

BACKGROUND

Carbon-dioxide elimination during high-frequency oscillatory ventilation (HFOV) is thought to be proportional to the carbon dioxide diffusion coefficient (DCO₂ ) which is calculated as frequency x (tidal volume)² . DCO₂ can be used to as an indicator of CO₂ elimination but values obtained in different patients cannot be directly compared.

OBJECTIVES

To analyze the relationship between DCO₂ , the weight-corrected DCO₂ (DCO₂ corr) and blood gas PCO₂ values obtained from infants receiving HFOV.

METHODS

DCO₂ data were obtained from 14 infants at 1/s sampling rate and the mean DCO₂ was determined over 10 min periods preceding the time of the blood gas. DCO₂ corr was calculated by dividing the DCO₂ by the square of the body weight in kg.

RESULTS

Weight-correction significantly reduced the inter-individual variability of DCO₂ . When data from all the babies were combined, standard DCO₂ showed no correlation with PCO₂ but DCO₂ corr showed a weak but statistically significant inverse correlation. The correlation was better when the endotracheal leak was <10%. There was significant inverse but weaker correlation between the HFOV tidal volume (VThf) and the PCO₂ . In any baby, DCO₂ corr >50 mL² /sec/kg² or VThf > 2.5 mL/kg was rarely needed to avoid hypercapnia.

CONCLUSIONS

Weight-correction of DCO₂ values improved its comparability between patients. Weight-corrected DCO₂ correlated better with PCO₂ than uncorrected DCO₂ but the correlation was weak.

Effect of the I/E ratio on CO2 removal during high-frequency oscillatory ventilation with volume guarantee in a neonatal animal model of RDS

The objective of this study was to analyze the effect of I/E ratio on carbon dioxide (CO2) elimination during high-frequency oscillatory ventilation (HFOV) combined with volume guarantee (VG). Five 2-day-old piglets were studied before and after a bronchoalveolar lavage (BAL). The effect of an I/E ratio of 1:1 and 1:2 with (VG-ON) and without VG (VG-OFF) on PaCO2, as well as delta and mean airway pressures at the airway opening (∆Phf-ao, mPaw-ao) and at the tracheal level (∆Phf-t, mPaw-t) were evaluated at frequencies of 5, 8, 11, and 14 Hz. With the VG-ON, PaCO2 was significant lower with the I/E ratio of 1:2 at 5 Hz compared with the 1:1. mPaw-t was higher than mPaw-ao, with 1:1 I/E ratio, and on VG-ON, this difference was statistically significant.

CONCLUSION

"In this animal study and with this ventilator, the I/E ratio of 1:1 compared to 1:2 in HFOV and VG-ON did not produce a higher CO2 lavage as when HFOV was used without the VG modality. Even more, a lower PaCO2 was found when using the lower frequency and 1:2 ratio compared to 1:1. So in contrast to non-VG HFOV mode, using a fixed tidal volume, no significant changes on CO2 elimination are observed during HFOV when the I/E ratios of 1:1 and 1:2 are compared at different frequencies."

WHAT IS KNOWN

•The tidal volume on HFOV is determinant in CO 2 removal, and this is generated by delta pressure and the length of the inspiratory time. What is New: •HFOV combined with VG, an I/E ratio of 1:2 is more effective to remove CO 2 , and this is not related to the tidal volume.

Using very high frequencies with very low lung volumes during high-frequency oscillatory ventilation to protect the immature lung. A pilot study

OBJECTIVE

High-frequency oscillatory ventilation (HFOV) has been described as a rescue therapy in severe respiratory distress syndrome (RDS) with a potential protective effect in immature lungs. In recent times, HFOV combined with the use of volume guarantee (VG) strategy has demonstrated an independent effect of the frequency on tidal volume to increase carbon-dioxide (CO2) elimination. The aim of this study was to demonstrate the feasibility of using the lowest tidal volume on HFOV+VG to prevent lung damage, maintaining a constant CO2 elimination by increasing the frequency.

STUDY DESIGN

Newborn infants with RDS on HFOV were prospectively included. After adequate and stable ventilation using a standard HFOV strategy, the tidal volume was fixed using VG and decreased while the frequency was increased to the highest possible to maintain a constant CO2 elimination. Pre- and post-PCO2, delta pressure and tidal volume obtained in each situation were compared.

RESULT

Twenty-three newborn infants were included. It was possible to increase the frequency while decreasing the tidal volume in all patients, maintaining a similar CO2 elimination, with a tendency to a lower mean PCO2 after reaching the highest frequency. High-frequency tidal volume was significantly lower, 2.20 ml kg(-1) before vs 1.59 ml kg(-1) at the highest frequency.

CONCLUSION

It is possible to use lower delivered tidal volumes during HFOV combined with VG and higher frequencies with adequate ventilation to allow minimizing lung injury.

Impact of Volume Guarantee on High-Frequency Oscillatory Ventilation in Preterm Infants: A Randomized Crossover Clinical Trial

BACKGROUND

High-frequency oscillatory ventilation (HFOV) with volume guarantee (VG) is a new ventilation mode that allows the clinician to set a mean tidal volume to be delivered.

OBJECTIVE

This study aimed to investigate whether HFOV with a VG option may result in constant tidal volume delivery and less fluctuant CO2 levels compared to HFOV alone in premature infants with respiratory distress syndrome (RDS).

METHODS

Inborn infants at less than 32 weeks of gestation with RDS requiring invasive mechanical ventilation were eligible. Patients were randomized to receive HFOV + VG or HFOV alone as the initial ventilator mode and then crossed over to the other mode. HFOV was performed with 'optimal lung volume strategy' during both of the periods.

RESULTS

Twenty infants were evaluated. The mean high-frequency tidal volume (VThf) and CO2 diffusion coefficient (DCO2) were significantly higher in the HFOV + VG mode than HFOV alone. HFOV + VG maintains VThf within the target range more consistently than HFOV. The incidences of hypocarbia and hypercarbia were lower in HFOV with VG than HFOV alone.

CONCLUSION

This is the first prospective, randomized, short-term crossover clinical study that compared HFOV with and without VG in infants with acute RDS. Because of the lower VThf fluctuation and lower incidences of out-of-target PCO2 levels, HFOV combined with VG seems to be feasible for preterm infants. However, the results should be interpreted with caution due to the small sample size and short-term crossover design of the study.