Comparative study of two different modes of noninvasive home mechanical ventilation in chronic respiratory failure

Impact of end-expiratory pressure fluctuation on tidal volume in the trilevel positive airway pressure mode

INTRODUCTION

In noninvasive positive-pressure ventilation (NPPV), the changes in the expiratory positive airway pressure (EPAP) directly affect the magnitude of the tidal volume.

OBJECTIVES

This experimental study aims to verify the precise effects of end-expiratory fluctuation on the body tidal volume to better assist NPPV in clinical practice.

METHODS

We selected the TestChest-simulated lung simulation of different populations, including healthy subjects (normal group), patients with chronic obstructive pulmonary disease (COPD) with emphysema as their primary phenotype (COPD1 group), and patients with COPD with bronchitis as their primary phenotype (COPD2 group).

RESULTS

Regarding the tidal volume curves of the three groups under various conditions, sixfold charts revealed that the tidal volume changed with the end-expiratory pressure fluctuations. In addition, regression coefficients for end-expiratory pressure fluctuations, (IPAP-EPAP) and (IPAP-EEPAP) exhibited a significant contribution to the tidal volume. The two coefficients in the normal, COPD1 and COPD2 groups were 52.294 and 10.414, 46.192 and -8.816, and 11.922 and 17.947, respectively. The circuit simulation results showed that the simulation curve fitted the experimental curve better by changing the coefficient of the descending edge of the expiratory phase.

CONCLUSIONS

The study results suggest that the end-expiratory pressure fluctuation affects the body tidal volume. Compared with the bilevel positive airway pressure (PAP), the trilevel PAP provides additional respiratory support to the body during a respiratory difference in initial respiration and descent.

The Feasibility of Domiciliary Non-Invasive Mechanical Ventilation due to Chronic Respiratory Failure in Very Elderly Patients

OBJECTIVES

The aim of this study was to investigate the use of domiciliary non-invasive mechanical ventilation (NIMV) in very elderly patients (age 80 and over).

MATERIALS AND METHODS

This retrospective study included a total of 44 patients aged 80 years or older, who were admitted to the Health Sciences University, Süreyyapaşa Chest Diseases and Thoracic Surgery Training and Research Hospital, Pulmonary Intensive Care Outpatient Clinic between 2012 and 2018 and applied NIMV for chronic respiratory failure. The patients were divided into two groups: survivors (n=15) and non-survivors (n=29). Data were obtained from the retrospectively formed hospital database. The characteristics of patients, comorbidities, NIMV compliance, pulmonary function tests, and blood gas analyses were compared between the survivors and non-survivors.

RESULTS

From the retrospective analysis of 44 cases, the non-survivors were found to have a significantly shorter duration of domiciliary NIMV (737 days vs. 890 days, p=0.027) and lower hemoglobin concentration (11.1 g/L vs. 12.9 g/L, p=0.004). The number of comorbid conditions, pulmonary function test, and blood gas analyses results did not differ significantly between the groups. Compliance was moderate in this elderly population, at 4.9±1.9 h/day (range: 0.8-9.1 h/day). NIMV was well-tolerated in 36 of the 44 elderly patients (81.8%). Overall mortality was 65.9%.

CONCLUSION

Domiciliary NIMV can be of benefit to very elderly patients, and age is not an obstacle. Therefore, this population should not be excluded from this treatment solely on the basis of age.

Effect of expiratory positive airway pressure on tidal volume during non-invasive ventilation

During non-invasive ventilation (NIV), tidal volume ( V_t) will depend upon the difference between inspiratory and expiratory positive airway pressure (IPAP and EPAP, respectively), provided the respiratory muscles are relaxed and the lungs and chest wall therefore move along their passive pressure-volume curves. To test this hypothesis, we studied the effect of increasing EPAP during pressure-controlled modes of NIV in 30 long-term ventilator users (10 each with scoliosis, obesity hypoventilation or neuromuscular disorders). While maintaining the same IPAP, addition of 5 cmH₂O of EPAP reduced mean V_t by 167 ml; 10 cmH₂O reduced V_t by 367 ml. This pattern was seen in all three patient groups. EPAP has several potential advantages, for example maintaining upper airway patency, preventing basal atelectasis and facilitating triggering. EPAP does, however, appear to reduce V_t. Decreasing EPAP is an alternative to increasing IPAP if measurements of gas exchange during NIV indicate that ventilation is inadequate.

Nocturnal non-invasive ventilation for cardio-respiratory disorders in adults

Following the classic 'iron lung' non-invasive negative pressure ventilator, non-invasive positive pressure ventilation (NIPPV), particularly used 'nocturnally' has developed a broad role in both the acute hospital setting and domiciliary long-term use for many cardio-respiratory disorders associated with acute and chronic ventilatory failure. This role is based in part upon the perceived relative ease of application and discontinuation of NIPPV, ability to avoid intubation or tracheostomy and their associated morbidities and availability of increasingly portable pressure and volume cycled NIPPV devices. Nevertheless, the many methodologies necessary for optimal NIPPV use are often underappreciated by health care workers and patients alike. This review focuses on the rationale, practice, and future directions for 'nocturnal' use of non-invasive positive pressure ventilation (nNIV) in cardio-respiratory disorders in adults which are commonly associated with sleep-related apnea, hypoventilation and hypoxemia: congestive heart failure (CHF), chronic obstructive pulmonary disease (COPD), obesity hypoventilation syndrome (OHS), cystic fibrosis (CF) and neuromuscular disorders.

Predictors of mortality in chest wall disease treated with noninvasive home mechanical ventilation

RATIONALE

The long-term evolution of patients with chest wall disease and chronic respiratory failure treated with noninvasive home mechanical ventilation (NIHMV) is poorly known.

OBJECTIVES

The aim of this prospective observational study was to analyze the variables associated with mortality in a cohort of chest wall disease patients with chronic respiratory failure undergoing long-term follow-up after starting treatment with NIHMV.

METHODS

Chest wall disease patients who began NIHMV between 1996 and 2005 were followed up, with death as the primary outcome. The patients' clinical characteristics, lung function, and arterial blood gases were recorded at the start of treatment. Patients were seen and evaluated 1 month after starting NIHMV. The prognostic value of clinical and functional variables were assessed by Cox regression analyses.

MAIN RESULTS

We included 110 patients, 61 with tuberculosis sequelae and 49 with kyphoscoliosis. By the end of follow-up, 34 patients (28%) had died. The 5-year survival was 69% in those with tuberculosis sequelae and 75% in kyphoscoliosis. PaCO(2) ≥50 mmHg at 1 month of home ventilation and comorbidity (Charlson Index ≥3) were independent predictors of mortality.

CONCLUSION

Our results suggest that PaCO2 levels ≥50 mmHg at 1 month after starting noninvasive home mechanical ventilation and the presence of comorbid conditions are risk factors for mortality in patients with chest wall disease. The importance of early detection of suboptimal home ventilation as well as comorbidities is highlighted.