The use of head helmets to deliver noninvasive ventilatory support: a comprehensive review of technical aspects and clinical findings

A helmet, comprising a transparent hood and a soft collar, surrounding the patient’s head can be used to deliver noninvasive ventilatory support, both as continuous positive airway pressure and noninvasive positive pressure ventilation (NPPV), the latter providing active support for inspiration. In this review, we summarize the technical aspects relevant to this device, particularly how to prevent CO2 rebreathing and improve patient–ventilator synchrony during NPPV. Clinical studies describe the application of helmets in cardiogenic pulmonary oedema, pneumonia, COVID-19, postextubation and immune suppression. A section is dedicated to paediatric use. In summary, helmet therapy can be used safely and effectively to provide NIV during hypoxemic respiratory failure, improving oxygenation and possibly leading to better patient-centred outcomes than other interfaces.

Optimizing Patient–Ventilator Synchrony Utilizing Radar-Based Respiratory Features for Monitoring COVID-19 Patients

During this COVID-19 pandemic time, an unprecedented number of patients with severe respiratory illness require intensive care units (ICUs) under mechanical ventilation (MV) for sustaining life. Patient–ventilator asynchrony (PVA) is very common, and it occurs due to the mismatch between the normal variability of the patients’ breathing patterns and ventilator parameters. Asynchronies during invasive ventilation are causing the patients discomfort, fatigue, anxiety, neurovascular nerve damage, and mortality. However, currently, the only way to detect the asynchrony is through visual inspections by the healthcare professionals and adjust manually. In this article, we propose an opinion on the conceptual framework of a system composed of radio frequency (RF)-based noncontact life-sensing technology that can extract different respiratory features unobtrusively and continuously and can reduce the patient–ventilator asynchrony. After extracting respiratory features of patients from the radar data, it can provide optimally and continuously supplemental oxygen by adjusting the function of the existing mechanical ventilator. This will reduce the sufferings and mortalities, as well as less stress for emergency nurses and doctors to handle patients more effectively.

A Novel Method to Evaluate Patient-Ventilator Synchrony during Mechanical Ventilation

The synchrony of patient-ventilator interaction affects the process of mechanical ventilation which is clinically applied for respiratory support. The occurrence of patient-ventilator asynchrony (PVA) not only increases the risk of ventilator complications but also affects the comfort of patients. To solve the problem of uncertain patient-ventilator interaction in the mechanical ventilation system, a novel method to evaluate patient-ventilator synchrony is proposed in this article. Firstly, a pneumatic model is established to simulate the mechanical ventilation system, which is verified to be accurate by the experiments. Then, the PVA phenomena are classified and detected based on the analysis of the ventilator waveforms. On this basis, a novel synchrony index SIhao is established to evaluate the patient-ventilator synchrony. It not only solves the defects of previous evaluation indexes but also can be used as the response parameter in the future research of ventilator control algorithms. The accurate evaluation of patient-ventilator synchrony can be applied to the adjustment of clinical strategies and the pathological analyses of patients. This research can also reduce the burden on clinicians and help to realize the adaptive control of the mechanical ventilation and weaning process in the future.

Noninvasive Neurally Adjusted Ventilator Assist Ventilation in the Postoperative Period Produces Better Patient-Ventilator Synchrony but Not Comfort

Background. Noninvasive neurally adjusted ventilatory assist (NAVA) has been shown to improve patient-ventilator interaction in many settings. There is still scarce data with regard to postoperative patients indicated for noninvasive ventilation (NIV) which this study elates. The purpose of this trial was to evaluate postoperative patients for synchrony and comfort in noninvasive pressure support ventilation (NIV-PSV) vs. NIV-NAVA. Methods. Twenty-two subjects received either NIV-NAVA or NIV-PSV in an object-blind, prospective, randomized, crossover fashion (observational trial). We evaluated blood gases and ventilator tracings throughout as well as comfort of ventilation at the end of each ventilation phase. Results. There was an effective reduction in ventilator delays (p<0.001) and negative pressure duration in NIV-NAVA as compared to NIV-PSV (p<0.001). Although we used optimized settings in NIV-PSV, explaining the overall low incidence of asynchrony, NIV-NAVA led to reductions in the NeuroSync-index (p<0.001) and all types of asynchrony except for double triggering that was significantly more frequent in NIV-NAVA vs. NIV-PSV (p=0.02); ineffective efforts were reduced to zero by use of NIV-NAVA. In our population of previously lung-healthy subjects, we did not find differences in blood gases and patient comfort between the two modes. Conclusion. In the postoperative setting, NIV-NAVA is well suitable for use and effective in reducing asynchronies as well as a surrogate for work of breathing. Although increased synchrony was not transferred into an increased comfort, there was an advantage with regard to patient-ventilator interaction. The trial was registered at the German clinical Trials Register (DRKS no.: DRKS00005408).

Tracheal opening manoeuvre (PEEP-20) in a patient with bronchopulmonary dysplasia and severe tracheobronchomalacia with neurally adjusted ventilatory assist (NAVA)

Bronchopulmonary dysplasia (BPD) is occasionally associated with tracheobronchomalacia, and it is this combination that can lead to serious outcomes. The most severe cases require tracheostomies, ventilatory support and eventually even tracheal stents or surgery. Ventilation in patients with tracheomalacia is complicated without a good patient-ventilator synchrony; the neurally adjusted ventilatory assist (NAVA) mode is potentially beneficial in these cases. This case report presents a patient affected by BPD and severe tracheobronchomalacia who was tracheostomised and ventilated 24 hours a day and who suffered from episodes of airway collapse despite using the NAVA mode. It was necessary to increase the positive end-expiratory pressure to 20 cmH2O (the PEEP-20 manoeuvre) for several minutes during an episode; this allowed the trachea to remain open and allowed us to optimise the patient’s ventilation. This strategy has previously been described in a patient with tracheomalacia, reducing the frequency and need for sedation in the following episodes.

Interfacility Ventilator Management

Treating persistent hypoxia while attempting to transport a patient from one health care setting to a destination facility can be one of the most stressful situations emergency medical services providers face. In some cases, the primarily pathology may not be well defined. This case reviews the approach to managing a critically ill patient who is mechanically ventilated and is being transferred to a quaternary center for continued management. The case works through a differential diagnosis of hypoxemia in a mechanically ventilated patient. It also includes dynamic adjustments of the ventilator to maximize success and reduce any potential iatrogenic complications. Finally, adequate sedation is pivotal to promote ventilator synchrony and patient comfort. This case illustrates the nuances of sedation and when neuromuscular blockade should be considered.