Neurally adjusted ventilator assist in very low birth weight infants:Current status

Continuous improvements in perinatal care have resultedin increased survival of premature infants.Their immature lungs are prone to injury with mechanical ventilation and this may develop into chronic lung disease(CLD) or bronchopulmonary dysplasia.Strategies to minimize the risk of lung injury have been developed and include improved antenatal management(education,regionalization,steroids,and antibiotics),exogenous surfactant administration and reduction of barotrauma by using exclusive or early noninvasive ventilatory support.The most frequently used mode of assisted ventilation is pressure support ventilation that may lead to patientventilator asynchrony that is associated with poor outcome.Ventilator-induced diaphragmatic dysfunction or disuse atrophy of diaphragm fibers may also occur.This has led to the development of new ventilation modes including neurally adjusted ventilatory assist(NAVA).This ventilation mode is controlled by electrodes embedded within a nasogastric catheter which detect the electrical diaphragmatic activity(Edi) and transmit it to trigger the ventilator in synchrony with the patient's own respiratory efforts.This permits the patient to control peak inspiratory pressure,mean airway pressure and tidal volume.Back up pressure control(PC) is provided when there is no Edi signal and no pneumatic trigger.Compared with standard conventional ventilation,NAVA improves blood gas regulation with lower peak inspiratory pressure and oxygen requirements in preterm infants.NAVA is safe mode of ventilation.The majority of studies have shown no significant adverse events in neonates ventilated with NAVA nor a difference in the rate of intraventricular hemorrhage,pneumothorax,or necrotizing enterocolitis when compared to conventional ventilation.Future large size randomized controlled trials should be established to compare NAVA with volume targeted and pressure controlled ventilation in newborns with mature respiratory drive.Most previous studies and trials were not sufficiently large and did not include longterm patient oriented outcomes.Multicenter,randomized,outcome trials are needed to determine whether NAVA is effective in avoiding intubation,facilitating extubation,decreasing time of ventilation,reducing the incidence ofCLD,decreasing length of stay,and improving long-term outcomes such as the duration of ventilation,length of hospital stay,rate of pneumothorax,CLD and other major complications of prematurity.In order to prevent barotrauma,next generations of NAVA equipment for neonatal use should enable automatic setting of ventilator parameters in the backup PC mode based on the values generated by NAVA.They should also include an upper limit to the inspiratory time as in conventional ventilation.The manufacturers of Edi catheters should produce smaller sizes available for extreme low birth weight infants.Newly developed ventilators should also include leak compensation and high frequency ventilation.A peripheral flow sensor is also essential to the proper delivery of all modes of conventional ventilation as well as NAVA.

Unexpected complication during extracorporeal membrane oxygenation support: Ventilator associated systemic air embolism

Systemic air embolism through a bronchovenous fistu-la(BVF) has been described in patients undergoing positive-pressure ventilation. However, no report has mentioned the potential risks of systemic air embolism through a BVF in patients undergoing extracorporeal membrane oxygenation(ECMO). Positive-pressure ventilation and ECMO support in patients with lung injury can increase the risk of systemic air embolism through a BVF. Increased alveolar pressure, decreased pulmonary venous pressure, and anticoagulation are thought to be the factors that contribute to this complication. Here, we present a case of systemic air embolism in a patient with ECMO and mechanical ventilator support.

Influence of Leakage from Non-Invasive Positive Pressure Ventilation Mask on FiO₂Value Delivered by Home Oxygen Therapy Concentrator: A Bench Study on Simulating Patients with Chronic Obstructive Pulmonary Disease

Introduction: During the application of non-invasive positive pressure ventilation (NPPV) therapy in home mechanical ventilation (HMV), leaks in the NPPV mask may occur owing to the position of the mask due to conditions such as skin disorders. Methods: To investigate whether such a leak affects FiO2 supplied to the alveoli, we simulated a patient with chronic obstructive pulmonary disorder during NPPV in HMV. In addition, FiO2 was measured in the portion assumed to be the mouth and lungs while setting the flow of the oxygen concentrator and leak amount based on a previous study. Results: FiO2 supplied to the lungs increased statistically significantly upon increasing the amount of leak (P Conclusions: We observed that FiO2 supplied to alveoli can be reduced by a leak in the NPPV mask. Because our results differ from those previously reported, we believe that further studies should reassess the selection of respirators and oxygen concentrators.

Non-Invasive Pressure Support Ventilation in Major Lung Resection for High Risk Patients: Does It Matter?

Background and purpose: Patients with severely impaired pulmonary function have an increased operative risk for major lung resection. The clinical benefits of pre- and perioperative, non-invasive pressure support ventilation (NIPSV) have up to now not been extensively evaluated. Patients with severely reduced pulmonary function were investigated in this prospective and randomised single centre clinical trial. Methods: Standard pulmonary evaluation was performed in all patients before major lung resection. To predict postoperative pulmonary function, a lung perfusion-ventilation scan was carried out. All patients enrolled in the study were instructed preoperatively on how to use a NIPSV respirator. Af-ter lung resection patients were randomised either for continuation of NIPSV or for standard treatment. Results: Of the 52 patients assessed, 21 patients met the inclusion criteria for the study protocol. Predicted mean postoperative FEV1 was 1.10 L (range 0.92 - 1.27 L). Lobectomy was performed in 14 patients, pneumonectomy in 6 patients and a segmentectomy in 1 patient. No inhospital deaths occurred. Pulmonary complications (reintubation, pneumonia) were more frequent in the NIPSV group than in the control group (3 patients versus 1 patient), without statistical significance (p = 0.31). Conclusions: We observed no mortality and a low morbidity in this high risk group. Postoperative continuation of NIPSV had no beneficial effect on the clinical outcome. Preoperative conditioning with NIPSV, however, seems to be a suitable tool for patients with severely impaired pulmonary function. This study may serve therefore as basis for further investigations for the potential clinical benefits of prophylactic NIPSV in major lung surgery.

Clinical efficacy and safety of recruitment maneuver in patients with acute respiratory distress syndrome using low tidal volume ventilation： a multicenter randomized controlled clinical trial

Background The recruitment maneuver （RM） has been shown to improve oxygenation in some patients with acute respiratory distress syndrome. But there is a lack of standardization and lack of clinical studies to prove the improvement on clinical outcome. We conducted this study to evaluate the clinical efficacy and safety of the RM in patients with acute respiratory distress syndrome （ARDS） using Iow tidal volume ventilation.Methods We randomly assigned 110 patients with ARDS from 14 Chinese intensive care units （ICUs） at the tertiary teaching hospitals. Patients with PaO2 ≤200 mmHg at FiO2 1.0 and PEEP ≥10 cmH2O were included in the study.Patients were randomized into two groups： control group and RM group. The tidal volume was set to 6-8 mi per kilogram of predicted body weight （PBW） in both groups. RM was performed by continuous positive airway pressure （CPAP） of 40 cmH2O maintained for 40 seconds. RMs was conducted every eight hours for the first five days, or stopped within five days if the patient reached the weaning standard.Results One hundred and ten patients had completed the requirements for the primary study goals, 55 from the RM group and 55 control patients. Baseline characteristics remained similar in the two groups. In the RM group the PaO2/FiO2 was significantly increased compared to baseline at 120 minutes after RM on day one and day two （P=0.007and P=0.001）. There were no significant differences between the RM and control group in hospital mortality （41.8% vs.56.4%, P=0.13）, 28-day mortality （29.1% vs. 43.6%, P=0.11） and ventilator-free days at day 28 （10.8±10.1 vs. 7.4±10.0,P=0.08）. ICU mortality （32.7% vs. 52.7%, P=0.03）, the rate of survival with unassisted breathing for at least 48 consecutive hours at day 28 （58.2% vs. 36.2%, P=0.02）, and nonpulmonary organ failure-free days at day 28 （17.4±11.1vs. 13.0±12.0, P=0.03） favored the RM group. There was no significant difference in mean blood pressure and heart rate before RM and at 30, 60, 120 minutes after RM. There was no incidence of barotraumas.Conclusions RM was safe and useful for improving oxygenation in patients with ARDS who were ventilated with a low tidal volume, with a beneficial impact on their clinical outcome.

Anesthesia with propofol-remifentanil combined with rocuronium for bronchial foreign body removal in children: Experience of 2886 cases

Importance: The appropriate anesthetic method can reduce the complications of children with tracheal foreign body and reduce the mortality rate of children. What kind of anesthetic method to choose has always been the focus of debate. Purpose: To evaluate the efficacy and safety of anesthesia with propofol-remifentanil combined with rocuronium for foreign body aspiration (FBA) removal with the positive-pressure ventilation technique. Methods: Medical records of patients who underwent bronchoscopy for evaluation of FBA in our unit from January 2015 to January 2018 were retrospectively reviewed. Demographic data (age and sex), nature of foreign body and location, complications, length of hospital stay and outcome were analyzed. Results: A total of 2886 children were included in this study. The median age was 24 months (8 months to 10 years). FBA was detected and removed in 95.6％ of patients. The average operation time was 17 ± 5 min and average length of hospital stay was 2 days. Observed peri-interventional complications included desaturation (n = 66), laryngospasm (n = 19), laryngeal or subglottic edema (n = 15), irritating cough (n = 3), body movement (n = 76) and pneumonia (n = 206). No deaths occurred during hospitalization or follow-up in this series. Interpretation: Anesthesia with propofol-remifentanil combined with rocuronium under positive-pressure ventilation is an effective and safe technique during FBA removal in children.