Effect of the change of mechanical ventilation mode on cerebral oxygen saturation level in neonates

BACKGROUND

This study aimed to apply near-infrared spectroscopy (NIRS) to monitor cerebral oxygen saturation (SrO2) level in neonates before and after the change of mechanical ventilation mode, and thus, the effects of the change of mechanical ventilator mode on SrO2 level in neonates were assessed.

METHODS

This trial was designed as an observational study .A total of 70 neonates who were admitted to the Department of Neonatology of Beijing Luhe Hospital Affiliated to Capital Medical University (Beijing, China) between September 2019 and October 2021 and required respiratory support were included. The variations of SrO2 level before and after the change of mechanical ventilation mode, including changing from Synchronized intermittent mandatory ventilation (SIMV) to noninvasive ventilation (NIV, group 1), and from NIV to oxygen inhalation (group 2), were monitored by Enginmed EGOS-600 A. The changes of SrO2 level at 30 min before and 1 h after the change of ventilation mode were compared between the two groups.

RESULTS

The SrO2 level in the group 1 30 min before, as well as 10 min, 30 min, and 1 h after the change of ventilation mode was 62.54 ± 3.36%, 65.43 ± 3.98%, 64.38 ± 4.23%, and 64.63 ± 3.71%, respectively. The SrO2 level at all the points after the change of ventilation mode increased compared with 30 min before the change (P < 0.05). The SrO2 level in the group 2 at each time point was 62.67 ± 4.69%, 64.61 ± 5.00%, 64.04 ± 4.48%, and 64.55 ± 4.32%, respectively. Compared with 30 min before ventilator weaning, the SrO2 level at all the points after ventilator weaning increased (P < 0.05). Peak inspiratory pressure (PIP) excluding Nasal Continuous Positive Airway Pressure (NCPAP)) in group 1 was lower than that before extubation, and the difference was statistically significant (P = 0) (Table 7).

CONCLUSIONS

SrO2 level showed an increasing trend after the change of ventilation mode, and the increase of SrO2 level at 10 min after the change of ventilation mode was the most prominent. From SIMV to NIV, increased SrO2 levels may be associated with decreased PIP.

High-frequency oscillatory ventilation versus conventional ventilation in the respiratory management of term neonates with a congenital diaphragmatic hernia: a retrospective cohort study

Conventional mechanical ventilation (CMV) has been recommended as the first-line mode of respiratory support for neonates born with a congenital diaphragmatic hernia (CDH). However, older studies suggested that protective high-frequency oscillatory ventilation (HFOV) with low-mean airway pressure (MAP) may limit lung injury. We aimed to compare low-MAP HFOV with CMV in neonates with CDH in terms of patient outcomes. This retrospective cohort study was conducted in two French neonatal intensive care units: center 1 mainly used CMV, and center 2 mainly used HFOV with a low MAP. All term neonates with CDH born between 2010 and 2018 in these two centers were included. The primary outcome was the duration of oxygen therapy. Secondary outcomes were survival and duration of mechanical ventilation. A total of 170 patients (105 in center 1, 65 in center 2) were included. In center 2, 96% of patients were ventilated with HFOV versus 19% in center 1. After adjustment for perinatal data, there was no significant difference regarding duration of oxygen therapy (SHR 0.83, 95% CI [0.55-1.23], p = 0.35) or survival (HR 1.73, 95% CI [0.64-4.64], p = 0.28). Center 2 patients required longer mechanical ventilation and sedation.

CONCLUSION

First-line mode of mechanical ventilation was not associated with the duration of oxygen therapy or survival in neonates with CDH.

WHAT IS KNOWN

• Recommendations were given in favour of using the conventional mechanical ventilation in first intention in neonates with a congenital diaphragmatic hernia, since High frequency oscillation (HFO) has been associated with a higher morbidity.

WHAT IS NEW

• No differences between HFO and conventional mechanical ventilation were observed concerning the length of oxygen supply and the survival..

Using airway resistance measurement to determine when to switch ventilator modes in congenital diaphragmatic hernia: a case report

Background

Congenital diaphragmatic hernia is a deficiency of the fetal diaphragm resulting in herniation of the abdominal viscera into the thoracic cavity. The best method of respiratory management of congenital diaphragmatic hernia is unclear, but high frequency oscillatory ventilation is often used as the initial ventilator mode for severe congenital diaphragmatic hernia. When it becomes impossible to maintain the pre-ductal saturations, the timing of successful switching of the ventilation mode from high frequency oscillatory ventilation to conventional mechanical ventilation remains unclear. Herein, we reported two cases in which airway resistance measurements based on pulmonary function tests were used for making the decision to switch the ventilator mode from high frequency oscillatory ventilation to conventional mechanical ventilation in patients with left isolated congenital diaphragmatic hernia.

Case presentation

Two 0-day-old infants with congenital diaphragmatic hernia were admitted to our hospital. In both patients, high frequency oscillatory ventilation was started initially, and the levels of saturation gradually rose within a few hours after birth. After 24 h of high frequency oscillatory ventilation, the level of saturation decreased, and the dissociation of pre-ductal and post-ductal saturation re-occurred. The respiratory-system resistance was 515 and 403 cmH₂O·kg/L/s, respectively. Because the respiratory-system resistance was elevated, we decided to change the ventilator mode from high frequency oscillatory ventilation to conventional mechanical ventilation. After switching to conventional mechanical ventilation, the patients’ heart rate and saturation increased immediately.

Conclusions

In patients with congenital diaphragmatic hernia, resistance levels of > 400 cmH₂O·kg/L/s may indicate high airway resistance and suggest greater alveolar vibration attenuation. When respiratory-system resistance reaches over 400 cmH₂O·kg/L/s, it may be an optimal time for switching from high frequency oscillatory ventilation to conventional mechanical ventilation.

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

How to ventilate preterm infants with lung compliance close to circuit compliance: real-time simulations on an infant hybrid respiratory simulator

Circuit compliance close to lung compliance can create serious problems in effective and safe mechanical ventilation of preterm infants. We considered what ventilation technique is the most beneficial in this case. A hybrid (numerical-physical) simulator of infant respiratory system mechanics, the Bennett Ventilator and NICO apparatus were used to simulate pressure-controlled ventilation (PC) and volume-controlled ventilation with constant flow (VCV_CF) and descending flow (VCV_DF), under permissive hypercapnia (PHC) (6 ml kg^-1) and normocapnia (SV) (8 ml kg^-1) conditions. Respiratory rate (RR) was 36 or 48 min^-1 and PEEP was 0.3 or 0.6 kPa. Peak inspiratory pressure (PIP), mean airway pressure (MAP), and work of breathing by the ventilator (WOB) were lower (P < 0.01, 1 - β = 0.9) using the PHC strategy compared to the SV strategy. The WOB increased (P < 0.01; 1 - β = 0.9) when the RR increased. The PC, VCV_CF, and VCV_DF modes did not differ in minute ventilation produced by the ventilator (MV_V), but the PC mode delivered the highest minute ventilation to the patient (MV_T) (P < 0.01; 1 - β = 0.9) at the same PIP, MAP, and WOB. The most beneficial ventilation technique appeared to be PC ventilation with the PHC strategy, with lower RR (36 min^-1). Graphical abstract The effectiveness of an infant ventilation depending on circuit compliance to lung compliance ratio (C_v C_L ^-1) and inspiration time (T_i). V_V, V_T, tidal volume set on the ventilator and delivered to patient, respectively.

Intraoperative ventilation during thoracoscopic repair of neonatal congenital diaphragmatic hernia

PURPOSE

To evaluate the optimal ventilation mode during thoracoscopic repair (TR) of neonatal congenital diaphragmatic hernia (CDH), we compared high-frequency oscillatory ventilation (HFOV) with conventional mechanical ventilation (CMV).

METHODS

Twenty-three neonatal CDH cases who underwent TR without intraoperative inhalation of nitric oxide at our institution between 2007 and 2016 were reviewed. Patients were initially ventilated with HFOV, which was converted to CMV if the HFOV settings were decreased to FiO₂ <0.4, stroke volume <4 mL/kg and mean airway pressure <12 cmH₂O. Arterial blood gases in the perioperative period were compared between HFOV and CMV.

RESULTS

Seventeen patients were ventilated with HFOV (group I), and six patients were ventilated with CMV (group II). Preoperative PaCO₂ was significantly higher and pH was significantly lower in group I compared with group II. In both groups I and II, intraoperative PaCO₂ increased significantly and pH decreased significantly compared with preoperation. Although intraoperative PaCO₂ and pH were not different between the groups, group II showed greater worsening of intraoperative PaCO₂ and pH as compared to their respective preoperative values.

CONCLUSIONS

HFOV seems to prevent deterioration of hypercapnia and acidosis to a greater extent than CMV during TR in neonatal cases of CDH, although patients can also be ventilated with CMV.

Ventilation modalities in infants with congenital diaphragmatic hernia

Neonates with congenital diaphragmatic hernia are among the more complex patients to support with mechanical ventilation. They have particular features that add to the difficulties already present in the neonatal patient. A ventilation strategy tailored to the patient's underlying physiology rather than mode of ventilation is a crucial issue for clinicians treating these delicate patients.