High-frequency Oscillatory Ventilation Research Articles

Models of PaO2 response to the continuous distending pressure maneuver during high frequency oscillatory ventilation in healthy and ARDS lung model pigs

ABSTRACTPurpose/Aim: High-frequency oscillatory ventilation (HFOV) is a method of ventilation that theoretically achieves the goals of lung protective ventilation in acute respiratory distress syndrome (ARDS) patients. It is characterized by a rapid delivery of small tidal volumes at high frequencies oscillating around a continuous distending pressure (CDP). Optimization of CDP is not an easy task and it is titrated empirically in the clinical practice. The aim of this study is to investigate whether the level of CDP consistently affects the shape of the partial pressure of oxygen (PaO2) response to stepwise changes in CDP during HFOV of healthy and ARDS-induced pigs. Materials and Methods: We performed two stepwise maneuvers of CDP in 14 pigs: one before and one after the lung lavage, inducing ARDS. For each CDP step performed, we fitted a segment of PaO2 curve with a one-term power model. Results: PaO2 course follows shapes modeled by root, linear, quadratic, and cubic functions for values of PaO2 ≤ 110 mmHg and PaO2 ≤ 200 mmHg, before and after the lung lavage, respectively. PaO2 course follows a shape modeled exclusively by a root function for values of PaO2 > 110 mmHg and PaO2 > 200 mmHg, before and after the lung lavage, respectively. It is not possible to describe a relationship between the shape of the PaO2 course and the values of CDP. Conclusions: The PaO2 curve may give information about the level of recruitment of alveoli, but cannot be used for optimization of CDP level during HFOV in healthy and ARDS lung model pigs.

A noninvasive high frequency oscillation ventilator: Achieved by utilizing a blower and a valve.

After the High Frequency Oscillatory Ventilation (HFOV) has been applied in the invasive ventilator, the new technique of noninvasive High Frequency Oscillatory Ventilation (nHFOV) which does not require opening the patient's airway has attracted much attention from the field. This paper proposes the design of an experimental positive pressure-controlled nHFOV ventilator which utilizes a blower and a special valve and has three ventilation modes: spontaneous controlled ventilation combining HFOV, time-cycled ventilation combining HFOV (T-HFOV), and continuous positive airway pressure ventilation combining HFOV. Experiments on respiratory model are conducted and demonstrated the feasibility of using nHFOV through the control of fan and valve. The experimental ventilator is able to produce an air flow with small tidal volume (VT) and a large minute ventilation volume (MV) using regular breath tubes and nasal mask (e.g., under T-HFOV mode, with a maximum tidal volume of 100 ml, the minute ventilation volume reached 14,400 ml). In the process of transmission, there is only a minor loss of oscillation pressure. (Under experimental condition and with an oscillation frequency of 2-10 Hz, peak pressure loss was around 0%-50% when it reaches the mask.).

Too Little Oxygen: Ventilation, Prone Positioning, and Extracorporeal Membrane Oxygenation for Severe Hypoxemia.

Severe hypoxemia is associated with untoward outcomes in acute respiratory distress syndrome patients. Nevertheless, in and of itself, correction of hypoxemia is not an adequate surrogate outcome for mortality and clear evidence-based targets for correction of hypoxemia remain to be determined. At present, clinical management is directed toward achieving sufficient oxygenation while minimizing toxicity of ventilator-induced lung injury. The gold standard remains lung-protective mechanical ventilation, using lower-tidal volumes and pressure-limited ventilator titration. Notable progress in care includes further refinements in mechanical ventilation, consideration of salutatory effects of early prone positioning and neuromuscular blockade, and exploration of adjunctive extrapulmonary support with extracorporeal membrane oxygenation. This review focuses on three specific aspects: the evolving trend toward open lung ventilation, tempered by the recent cautionary experience with high-frequency oscillation ventilation; the evolution of prone positioning as a treatment for the most hypoxemic patients; and the continued future promise of extracorporeal support as a true rescue therapy.

A comparison of clinical efficacy between high frequency oscillatory ventilation and conventional ventilation with lung volume recruitment in pediatric acute respiratory distress syndrome: A randomized controlled trial.

Purpose:To determine the efficacy of lung volume recruitment maneuver (LVRM) with high frequency oscillatory ventilation (HFOV) on oxygenation, hemodynamic alteration, and clinical outcomes when compared to conventional mechanical ventilation (CV) in children with severe acute respiratory distress syndrome (ARDS).Materials:We performed a randomized controlled trial and enrolled pediatric patients who were diagnosed to have severe ARDS upon pediatric intensive care unit (PICU) admission. LVRM protocol combined with HFOV or conventional mechanical ventilation was used. Baseline characteristic data, oxygenation, hemodynamic parameters, and clinical outcomes were recorded.Results:Eighteen children with severe ARDS were enrolled in our study. The primary cause of ARDS was pneumonia (91.7%). Their mean age was 47.7 ± 61.2 (m) and body weight was 25.3 ± 27.1 (kg). Their initial pediatric risk of mortality score 3 and pediatric logistic organ dysfunction were 12 ± 9.2 and 15.9 ± 12.8, respectively. The initial mean oxygen index was 24.5 ± 10.4, and mean PaO2/FiO2 was 80.6 ± 25. There was no difference in oxygen parameters at baseline the between two groups. There was a significant increase in PaO2/FiO2 (119.2 ± 41.1, 49.6 ± 30.6, P = 0.01*) response after 1 h of LVRM with HFOV compare to CV. Hemodynamic and serious complications were not significantly affected after LVRM. The overall PICU mortality of our severe ARDS at 28 days was 16.7%. Three patients in CV with LVRM group failed to wean oxygen requirement and were cross-over to HFOV group.Conclusions:HFOV combined with LVRM in severe pediatric ARDS had superior oxygenation and tended to have better clinical effect over CV. There is no significant effect on hemodynamic parameters. Moreover, no serious complication was noted.

Streaming Caused by Oscillatory Flow in Peripheral Airways of Human Lung

Oscillatory flow facilitates gas exchange in human respiration system. In the present study, both numerical calculation and PIV (Particle Image Velocimetry) measurement indicate that, under the application of HFOV (High Frequency Oscillatory Ventilation), apparent steady streaming is caused and augmented in distal airways by the continuous oscillation, i.e., the core air moves downwards and the peripheral air evacuates upwards within bronchioles. The net flow of steady streaming serves to overcome the lack of tidal volume in HFOV and delivers fresh air into deeper lung region. Also, numerical calculations reveal that the intensity of steady streaming is mainly influenced by the geometry of airways with provided oscillatory frequency and tidal volume, and it rises with Re and Wo up to a Re of about 124 and Wo of about 5. Steady streaming is considered as an important factor for the ventilation efficiency of HFOV.

High frequency oscillatory ventilation in leptospirosis pulmonary hemorrhage syndrome: A case series study.

Hypoxemia in severe leptospirosis-associated pulmonary hemorrhage syndrome (LPHS) is a challenging clinical scenario not usually responsive to maximal support on mechanical ventilation. We described the efficacy and safety of high frequency oscillatory ventilation (HFOV) as rescue therapy in acute respiratory failure secondary to LPHS. This is a retrospective case study of five patients with diagnosis of severe LPHS, who were admitted to Intensive Care Unit from October 2014 to January 2015. They developed refractory hypoxemia on conventional mechanical ventilation and rescue therapy was indicated. All patients responded rapidly by showing improvements in oxygen index and PaO2/FiO2 ratio within first 72 h of therapy. Despite severity of illness evidenced by high Simplified Acute Physiological II and Sequential Organ Failure Assessment scores, all patients were discharged from hospital alive. In view of the rapid onset and extent of hemorrhage which may culminate quickly into asphyxiation and death, HFOV may indeed be lifesaving in severe LPHS.

Effect of Gas Oscillation-Induced Irreversible Flow in Transitional Bronchioles of Human Lung

Gas exchange in human lungs is established by several flow mechanisms. In the present study, the features of gas displacement in the distal bronchioles of a human lung are investigated by both numerical calculation and experimental observation with particle image velocimetry. The effect of respiration frequency is considered, such as high frequency oscillatory ventilation. By comparing the obtained results, it has been found that the redistribution of gas is attributed to irreversible flow, which is remarkable in higher frequencies oscillation with even lower tidal volumes. Owing to the continuous driving, a time-averaged net flow was induced and intensified by the oscillation. Thus, the gas in the centre region penetrated the deeper region and the outer gas was evacuated to the upper region. Consequently, this streaming contributes to prompt gas replacement. Furthermore, we analysed the effect of the respiration wave form to consider the flow acceleration. From this inspection, it was found that the enhanced inertial force tends to encourage the irreversible flow.

A case in which high frequency oscillatory ventilation was useful for treating respiratory failure during a Starnes operation for a neonate with Ebstein's anomaly

A case in which high frequency oscillatory ventilation was useful for treating respiratory failure during a Starnes operation for a neonate with Ebstein's anomaly

Recommendations for the Use of Inhaled Nitric Oxide Therapy in Premature Newborns with Severe Pulmonary Hypertension

Recommendations for the Use of Inhaled Nitric Oxide Therapy in Premature Newborns with Severe Pulmonary Hypertension

High-Frequency Oscillatory Ventilation in Pediatric Acute Lung Injury: A Multicenter International Experience.

We aim to describe current clinical practice, the past decade of experience and factors related to improved outcomes for pediatric patients receiving high-frequency oscillatory ventilation. We have also modeled predictive factors that could help stratify mortality risk and guide future high-frequency oscillatory ventilation practice. Multicenter retrospective, observational questionnaire study. Seven PICUs. Demographic, disease factor, and ventilatory and outcome data were collected, and 328 patients from 2009 to 2010 were included in this analysis. None. Patients were classified into six cohorts based on underlying diagnosis. We used univariate analysis to identify factors associated with mortality risk and multivariate logistic regression to identify independent predictors of mortality risk. An oxygenation index greater than 35 and immunocompromise exhibited the greatest predictive power (p < 0.0001) for increased mortality risk, and respiratory syncytial virus was associated with lowest mortality risk (p = 0.003). Differences in mortality risk as a function of oxygenation index were highly dependent on primary underlying condition. A trend toward an increase in oscillator amplitude and frequency was observed when compared with historical data. Given the number of centers and subjects included in the database, these findings provide a robust description of current practice regarding the use of high-frequency oscillatory ventilation for pediatric hypoxic respiratory failure. Patients with severe hypoxic respiratory failure and immunocompromise had the highest mortality risk, and those with respiratory syncytial virus had the lowest. A means of identifying the risk of 30-day mortality for subjects can be obtained by identifying the underlying disease and oxygenation index on conventional ventilation preceding the initiation of high-frequency oscillatory ventilation.

Multifrequency Oscillatory Ventilation in the Premature Lung: Effects on Gas Exchange, Mechanics, and Ventilation Distribution.

Despite the theoretical benefits of high-frequency oscillatory ventilation (HFOV) in preterm infants, systematic reviews of randomized clinical trials do not confirm improved outcomes. The authors hypothesized that oscillating a premature lung with multiple frequencies simultaneously would improve gas exchange compared with traditional single-frequency oscillatory ventilation (SFOV). The goal of this study was to develop a novel method for HFOV, termed "multifrequency oscillatory ventilation" (MFOV), which relies on a broadband flow waveform more suitable for the heterogeneous mechanics of the immature lung. Thirteen intubated preterm lambs were randomly assigned to either SFOV or MFOV for 1 h, followed by crossover to the alternative regimen for 1 h. The SFOV waveform consisted of a pure sinusoidal flow at 5 Hz, whereas the customized MFOV waveform consisted of a 5-Hz fundamental with additional energy at 10 and 15 Hz. Per standardized protocol, mean pressure at airway opening ((Equation is included in full-text article.)) and inspired oxygen fraction were adjusted as needed, and root mean square of the delivered oscillatory volume waveform (Vrms) was adjusted at 15-min intervals. A ventilatory cost function for SFOV and MFOV was defined as (Equation is included in full-text article.), where Wt denotes body weight. Averaged over all time points, MFOV resulted in significantly lower VC (246.9 ± 6.0 vs. 363.5 ± 15.9 ml mmHg kg) and (Equation is included in full-text article.)(12.8 ± 0.3 vs. 14.1 ± 0.5 cm H2O) compared with SFOV, suggesting more efficient gas exchange and enhanced lung recruitment at lower mean airway pressures. Oscillation with simultaneous multiple frequencies may be a more efficient ventilator modality in premature lungs compared with traditional single-frequency HFOV.

Mechanical ventilation modes for respiratory distress syndrome in infants: a systematic review and network meta-analysis.

IntroductionThe effects of different mechanical ventilation (MV) modes on mortality outcome in infants with respiratory distress syndrome (RDS) are not well known.MethodsWe searched the Cochrane Central Register of Controlled Trials (CENTRAL) in the Cochrane Library, EMBASE, MEDLINE, CINAHL, and Web of Science for studies published through April 2014 that assessed mortality in infants with RDS given different MV modes. We assessed studies for eligibility, extracted data, and subsequently pooled the data. A Bayesian fixed-effects model was used to combine direct comparisons with indirect evidence. We also performed sensitivity analyses and rankings of the competing treatment modes.ResultsIn total, 20 randomized controlled trials were included for the network meta-analysis, which consisted of 2,832 patients who received one of 16 ventilation modes. Compared with synchronized intermittent mandatory ventilation (SIMV) + pressure support ventilation (PSV), time-cycled pressure-limited ventilation (TCPL) (hazard ratio (HR) 0.290; 95% confidence interval (CI) 0.071 to 0.972), high-frequency oscillatory ventilation (HFOV) (HR 0.294; 95% CI 0.080 to 0.852), SIMV + volume-guarantee (VG) (HR 0.122; 95% CI 0.014 to 0.858), and volume-controlled (V-C) (HR 0.139; 95% CI 0.024 to 0.677) ventilation modes are associated with lower mortality. The combined results of available ventilation modes were not significantly different in regard to the incidences of patent ductus arteriosus and intraventricular hemorrhage.ConclusionCompared with the SIMV + PSV ventilation mode, the TCPL, HFOV, SIMV + VG, and V-C ventilation modes are associated with lower mortality.Electronic supplementary materialThe online version of this article (doi:10.1186/s13054-015-0843-7) contains supplementary material, which is available to authorized users.

High-frequency oscillation ventilation for hypercapnic failure of conventional ventilation in pulmonary acute respiratory distress syndrome.

IntroductionHigh-frequency oscillation ventilation (HFOV) is regarded as particularly lung protective. Recently, HFOV has been shown to be not beneficial for acute respiratory distress syndrome (ARDS) patients in general. Due to its special physical effects, it could be beneficial, however, in inhomogeneous ARDS. This study evaluates the effect of HFOV on PaCO2 removal in hypercapnic patients with ARDS of pulmonary origin.MethodsBetween October 2010 and June 2014 patients with ARDS of pulmonary origin with PaO2/FiO2 ratio >60 mmHg, but respiratory acidosis (pH <7.26) under optimized protective ventilation were switched to HFOV, using moderate airway pressure (adopting the mean airway pressure of the prior ventilation). Data from these patients were analyzed retrospectively; PaCO2 and pH before, 1 h and 24 h after the start of HFOV were compared.ResultsTwenty-six patients with PaO2/FiO2 ratio 139 ± 49 and respiratory acidosis (PaCO2 68 ± 12 mmHg) were put on HFOV after 17 ± 22 h of conventional ventilation. Mean airway pressure was 19 cm H2O (15 to 28). PaCO2 decreased significantly: after 1 hour the mean difference was −14 ± 10 mmHg; P <0.01 and after 24 hours −17 ± 12 mmHg; P <0.01; n = 24. CO2 clearance improved in all but two patients; in those, extracorporeal lung support was initiated. Oxygenation remained unchanged after 1 h and slightly increased after 24 h. No complications related to HFOV were observed. Twenty-two patients improved and could be weaned from HFOV. Twenty patients (77%) were alive on day 30.ConclusionsHFOV could be a useful alternative in patients with ARDS of pulmonary origin with hypercapnic failure of lung-protective conventional ventilation.Electronic supplementary materialThe online version of this article (doi:10.1186/s13054-015-0935-4) contains supplementary material, which is available to authorized users.

Use of High-Frequency Ventilation in the Pediatric Intensive Care Unit.

Objective To evaluate the clinical characteristics, ventilator settings, and gas exchange indices of patients placed on high-frequency percussive ventilation (HFPV) and high-frequency oscillatory ventilation (HFOV). Methods Retrospective observation of all consecutive patients aged 0 to 18 years with acute respiratory failure managed with high-frequency ventilation from the institution's introduction of HFPV on May 1, 2012, until July 10, 2013. Measurements and Main Results Twenty-seven patients underwent HFPV as a first mode of high-frequency ventilation and 16 patients underwent HFOV first. HFPV was used more frequently in patients with acute respiratory illnesses (p < 0.01), lower Pediatric Index of Mortality 2 scores (rank-sum p < 0.04), higher Spo 2/Fio 2 (SF) ratios (p < 0.01), and lower oxygen saturation indices (p < 0.01). HFPV patients showed increased SF ratios (p < 0.01) and decreased Paco 2 levels (p = 0.02) 6 hours after initiation, and HFOV patients showed no significant differences. Peak inspiratory pressures (HFPV) and mean airway pressures (HFOV) remained at or below 30 cm H2O at each time point. HFPV and HFOV patients had an average of 2.8 and 2.9 mode changes, respectively. Mortality was 15% in the HFPV group and 50% in the HFOV group. Conclusions HFPV is associated with rapid improvement in oxygenation and ventilation at acceptable airway pressures in patients with acute respiratory failure of various etiologies, primarily for those with difficulties of ventilation or secretion management. In our institution, HFOV appears to be initiated first in children with higher severity of illness.

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.

Congenital diaphragmatic hernia, management in the newborn.

Congenital diaphragmatic hernia (CDH) in the newborn poses challenges to the multi-disciplinary teams involved in its management. Mortality remains significantly high, despite growing understanding and treatment options. Early intubation of antenatally diagnosed cases is crucial in preventing deterioration and persistent pulmonary hypertension. Early recognition of cases not diagnosed on antenatal scan, with appreciation of differential diagnosis, requires an index of suspicion and imaging. Increasing options and modalities are available, with only modest, if any, survival advantage. Permissive hypercapnea and minimal ventilation have made the most significant impact on survival in modern era. High-frequency oscillatory ventilation (HFOV), inhaled nitric oxide (iNO), treatment of pulmonary hypertension, and ECMO are used in a somewhat stepwise manner for stabilisation. Delayed surgery has become established later in management plan. The impact of individual therapies (e.g. HFOV, iNO, ECMO) on outcome is difficult to ascertain. Little level 1 or 2 evidence exists. Randomised studies and reviews on the role of ECMO have not yet proven any long-term survival benefit. One pilot randomised study of thoracoscopic repair suggests increased acidosis; intraoperative blood gases and CO2 levels should be closely monitored. Monitoring tissue oxygenation should be considered. There is no evidence to suggest the best patch material.

Lung recruitment strategies

Mechanical ventilation in newborns, children and adults leads to lung injury and has been shown to induce the formation of proteinaceous lung oedema causing epithelial disruption and resulting in changes in lung perfusion. Lung injury leads to reduced compliance, worsening of shunt fraction and an inflammatory response that results from high end-inspiratory transpulmonary pressures (Ptp) and inadequate End Expiratory Lung Volume (EELV). Lung injury results if a lung is ventilated from collapsed state with each ventilator cycle. Thus the first concept of treatment in acute hypoxic respiratory failure is: “Open collapsed lung units and keep them open without overdistending them”. The open lung is one in which there is little or no atelectasis and an optimal gas exchange. Lung recruitment strategies transiently increase Ptp to reopen the alveolar units not aerated or poorly aerated but recruitable. Lung recruitment maneuvers may restore EELV resulting in more stable alveoli, and reduce shear stress associated with the alveolar cyclic opening and closing. Lung recruitment can be performed in several ways: in delivery room with a T-piece device, in the NICU setting by using a conventional or high frequency oscillation (HFO) ventilator, and is commonly achieved by increase of end-expiratory lung volume with positive end expiratory pressure (PEEP) or end inspiratory lung volume by inspiratory holds or sustained inflation. Recruitment during both, HFO and CMV (Conventional Mechanical Ventilation), follows similar concepts when using small tidal volume ventilation but is easier to achieve at bedside during HFO. The Sustained Inflation maneuver (SI) applies a high pressure to the lung for a short period (30 sec) before returning to previous mean airway pressures. This volume recruitment strategy has been shown to be as protective as high frequency oscillatory ventilation (HFO) at similar lung volumes. Infants treated with a SI in delivery room had improved short-term respiratory outcomes (reduced need of tracheal intubation and mechanical ventilation), but major outcomes (BPD Bronchopulmonary dysplasia- and/or death) were not improved. Recent reports describe improvements in arterial oxygenation with the use of recruitment maneuvers during CMV and/or HFO. However, the impact of these strategies on patient important outcomes such as survival is still unclear. Further clinical studies are needed to evaluate the efficacy of SI, including selection of patients, setting of SI maneuver in terms of duration and peak pressure, timing of surfactant administration. Further studies are also needed to elucidate the impact of recruitment maneuvers during mechanical ventilation, including survival and BPD.

Optimal ventilation strategy

Premature delivery, is always associated to the failure of respiratory transition and a delayed achievement of an adequate functional residual capacity. For this reason preterm babies (expecially the Extremely Low for Gestational Age -ELGA- infants) frequently need a respiratory support. Non-invasive ventilation (NIV) is widespread used in the management of respiratory distress even in ELGA infants without increasing of neonatal mortality or neurological impairment. The most recent meta-analysis and reviews on NIV approach demonstrated that NIV is a valid alternative to mechanical ventilation (MV) in the management of respiratory failure and resulted in significant reductions in the incidence of Bronchopulmonary dysplasia (BPD) amongst surviving infants [1,2]. Nevertheless, even if non-invasive respiratory support seems to be very efficacious in preterm babies, sometimes ELGA infants require MV. Pressure-limited ventilation is yet the standard mode in neonatal intensive care unit, because the attempts to use traditional volume-controlled ventilation it has been often impractical in very small preterm infants. Moreover pressure-limited ventilation continues to be the primary mode of ventilation in neonates because of its relative simplicity and ability to ventilate effectively despite large ETT leak. The major disadvantage of pressure-limited ventilation is that the tidal volume (VT) varies with changes in lung compliance (e.g after surfactant therapy). The consequences of such rapid improvements in compliance are inadvertent hyperventilation and lung injury from excessively large VT (volutrauma); inadvertent hyperventilation may induce hypocapnia, with high risk of cerebral damage. In literature there are extensive evidence that excessive volume, rather than pressure, is the key determinant of ventilator-induced lung injury (VILI). Inadequate (too small) VT also causes significant problems (atelectrauma): in particular inefficient gas exchange due to increased dead-space to VT ratio. Therefore in the last years volume-targeted ventilation has become an important standard of care in neonatal and pediatric respiratory support too. There are many volume-targeted ventilation modes to be used in neonatal period, but Volume Guarantee (VG) ventilation, it is the most extensively studied volume-targeted ventilation mode in the neonate with respiratory distress. The Cochrane review on volume-targeted ventilation resulted in significant reductions in duration of ventilation, rates of pneumothorax, significant reduction in intraventricular haemorrhage (IVH) and a reduction in the incidence of BPD amongst surviving infants, of borderline statistical significance [3]. The VG ventilation plus adequate PEEP and an open lung strategy [4], seems to be an adequate alternative to High frequency Oscillatory Ventilation (HFOV) in mechanically ventilated infants for RDS.

Application of respiratory support in perioperative period of congenital diaphragmatic hernia in neonates

Objective To explore the ventilation strategies and treatment outcomes in the neonates with congenital diaphragmatic hernia(CDH) during perioperative period. Methods We conducted a retrospective study of 13 infants with CDH in our NICU.Infants with prenatal diagnosis of CDH should be intubated immediately after delivery, then they were transferred to NICU and gave ventilator support.During pre-operation period, high-frequency oscillatory ventilation(HFOV) mode was used as initial therapy.Neonates with CDH-associated pulmonary hypertension received inhaled nitric oxide(iNO) therapy.The surgical repair of CDH was usually delayed until physiologic stabilization and improvement of pulmonary hypertension.After surgical repair, we still used HFOV mode.According to the pre-operation parameter, the parameters of postoperative ventilation were regulated.The ventilator mode was changed to conventional ventilation(synchronized intermittent mandatory ventilation+ pressure support ventilation) when FiO2≤40%, mean airway pressure≤10 cmH2O(1 cmH2O=0.098 kPa), blood gas analysis resulted within normal range, the target preductal saturation range was 85% to 95%.When the babies' spontaneous respiration maintained stronger, FiO2≤30%, mean airway pressure≤8 cmH2O, SaO2, blood gas analysis resulted within normal range, thoracic X-ray showed the lung border on the contralateral side between the 8th and the 9th rib, then we weaned ventilator support. Results This gentle ventilation strategies were routinely used in our center, and made a good therapeutic effect in infants with CDH.Eleven of 13 CDH cases smoothly passed the ventilator support, no one developed into bronchopulmonary dysplasia. Conclusion Infants with CDH should be intubated immediately after birth and give ventilator support in perioperative period.This gentle ventilation strategy to avoid barotrauma until vital organs functions are stabilized.In order to improve the survival rate of infants with CDH, multidisciplinary collaboration become very important. Key words: Congenital diaphragmatic hernia; Perioperative period; Ventilation strategies; High-frequency oscillation ventilation