Effects of Varying Levels of Inspiratory Assistance with Pressure Support Ventilation and Neurally Adjusted Ventilatory Assist on Driving Pressure in Patients Recovering from Hypoxemic Respiratory Failure

Effects of closed loop ventilation on ventilator settings, patient outcomes and ICU staff workloads - a systematic review

BACKGROUND

Lung protective ventilation is considered standard of care in the intensive care unit. However, modifying the ventilator settings can be challenging and is time consuming. Closed loop modes of ventilation are increasingly attractive for use in critically ill patients. With closed loop ventilation, settings that are typically managed by the ICU professionals are under control of the ventilator's algorithms.

OBJECTIVES

To describe the effectiveness, safety, efficacy and workload with currently available closed loop ventilation modes.

DESIGN

Systematic review of randomised clinical trials.

DATA SOURCES

A comprehensive systematic search in PubMed, Embase and the Cochrane Central register of Controlled Trials search was performed in January 2023.

ELIGIBILITY CRITERIA

Randomised clinical trials that compared closed loop ventilation with conventional ventilation modes and reported on effectiveness, safety, efficacy or workload.

RESULTS

The search identified 51 studies that met the inclusion criteria. Closed loop ventilation, when compared with conventional ventilation, demonstrates enhanced management of crucial ventilator variables and parameters essential for lung protection across diverse patient cohorts. Adverse events were seldom reported. Several studies indicate potential improvements in patient outcomes with closed loop ventilation; however, it is worth noting that these studies might have been underpowered to conclusively demonstrate such benefits. Closed loop ventilation resulted in a reduction of various aspects associated with the workload of ICU professionals but there have been no studies that studied workload in sufficient detail.

CONCLUSIONS

Closed loop ventilation modes are at least as effective in choosing correct ventilator settings as ventilation performed by ICU professionals and have the potential to reduce the workload related to ventilation. Nevertheless, there is a lack of sufficient research to comprehensively assess the overall impact of these modes on patient outcomes, and on the workload of ICU staff.

Individual response in patient's effort and driving pressure to variations in assistance during pressure support ventilation

BACKGROUND

During Pressure Support Ventilation (PSV) an inspiratory hold allows to measure plateau pressure (Pplat), driving pressure (∆P), respiratory system compliance (Crs) and pressure-muscle-index (PMI), an index of inspiratory effort. This study aims [1] to assess systematically how patient's effort (estimated with PMI), ∆P and tidal volume (Vt) change in response to variations in PSV and [2] to confirm the robustness of Crs measurement during PSV.

METHODS

18 patients recovering from acute respiratory failure and ventilated by PSV were cross-randomized to four steps of assistance above (+ 3 and + 6 cmH2O) and below (-3 and -6 cmH2O) clinically set PS. Inspiratory and expiratory holds were performed to measure Pplat, PMI, ∆P, Vt, Crs, P0.1 and occluded inspiratory airway pressure (Pocc). Electromyography of respiratory muscles was monitored noninvasively from body surface (sEMG).

RESULTS

As PSV was decreased, Pplat (from 20.5 ± 3.3 cmH2O to 16.7 ± 2.9, P < 0.001) and ∆P (from 12.5 ± 2.3 to 8.6 ± 2.3 cmH2O, P < 0.001) decreased much less than peak airway pressure did (from 21.7 ± 3.8 to 9.7 ± 3.8 cmH2O, P < 0.001), given the progressive increase of patient's effort (PMI from -1.2 ± 2.3 to 6.4 ± 3.2 cmH2O) in line with sEMG of the diaphragm (r = 0.614; P < 0.001). As ∆P increased linearly with Vt, Crs did not change through steps (P = 0.119).

CONCLUSION

Patients react to a decrease in PSV by increasing inspiratory effort-as estimated by PMI-keeping Vt and ∆P on a desired value, therefore, limiting the clinician's ability to modulate them. PMI appears a valuable index to assess the point of ventilatory overassistance when patients lose control over Vt like in a pressure-control mode. The measurement of Crs in PSV is constant-likely suggesting reliability-independently from the level of assistance and patient's effort.

Lung ultrasound to evaluate aeration changes in response to recruitment maneuver and prone positioning in intubated patients with COVID-19 pneumonia: preliminary study

BACKGROUND

This single-center preliminary prospective observational study used bedside ultrasound to assess the lung aeration modifications induced by recruitment maneuver and pronation in intubated patients with acute respiratory disease syndrome (ARDS) related to coronavirus 2019 disease (COVID-19). All adult intubated COVID-19 patients suitable for pronation were screened. After enrollment, patients underwent 1 h in a volume-controlled mode in supine position (baseline) followed by a 35-cmH₂O-recruitment maneuver of 2 min (recruitment). Final step involved volume-controlled mode in prone position set as at baseline (pronation). At the end of the first two steps and 1 h after pronation, a lung ultrasound was performed, and global and regional lung ultrasound score (LUS) were analyzed. Data sets are presented as a median and 25th-75th percentile.

RESULTS

From January to May 2022, 20 patients were included and analyzed. Global LUS reduced from 26.5 (23.5-30.0) at baseline to 21.5 (18.0-23.3) and 23.0 (21.0-26.3) at recruitment (p < 0.001) and pronation (p = 0.004). In the anterior lung regions, the regional LUS were 1.8 (1.1-2.0) following recruitment and 2.0 (1.6-2.2) in the supine (p = 0.008) and 2.0 (1.8-2.3) in prone position (p = 0.023). Regional LUS diminished from 2.3 (2.0-2.5) in supine to 2.0 (1.8-2.0) with recruitment in the lateral lung zones (p = 0.036). Finally, in the posterior lung units, regional LUS improved from 2.5 (2.3-2.8) in supine to 2.3 (1.8-2.5) through recruitment (p = 0.003) and 1.8 (1.3-2.2) with pronation (p < 0.0001).

CONCLUSIONS

In our investigation, recruitment maneuver and prone positioning demonstrated an enhancement in lung aeration when compared to supine position, as assessed by bedside lung ultrasound.

TRIAL REGISTRATION

www.

CLINICALTRIALS

gov , Number NCT05209477, prospectively registered and released on 01/26/2022.

Neurally Adjusted Ventilatory Assist vs. Conventional Mechanical Ventilation in Adults and Children With Acute Respiratory Failure: A Systematic Review and Meta-Analysis

Background

Patient-ventilator asynchrony is a common problem in mechanical ventilation (MV), resulting in increased complications of MV. Despite there being some pieces of evidence for the efficacy of improving the synchronization of neurally adjusted ventilatory assist (NAVA), controversy over its physiological and clinical outcomes remain. Herein, we conducted a systematic review and meta-analysis to determine the relative impact of NAVA or conventional mechanical ventilation (CMV) modes on the important outcomes of adults and children with acute respiratory failure (ARF).

Methods

Qualified studies were searched in PubMed, EMBASE, Medline, Web of Science, Cochrane Library, and additional quality evaluations up to October 5, 2021. The primary outcome was asynchrony index (AI); secondary outcomes contained the duration of MV, intensive care unit (ICU) mortality, the incidence rate of ventilator-associated pneumonia, pH, and Partial Pressure of Carbon Dioxide in Arterial Blood (PaCO2). A statistical heterogeneity for the outcomes was assessed using the I ² test. A data analysis of outcomes using odds ratio (OR) for ICU mortality and ventilator-associated pneumonia incidence and mean difference (MD) for AI, duration of MV, pH, and PaCO2, with 95% confidence interval (CI), was expressed.

Results

Eighteen eligible studies (n = 926 patients) were eventually enrolled. For the primary outcome, NAVA may reduce the AI (MD = -18.31; 95% CI, -24.38 to -12.25; p < 0.001). For the secondary outcomes, the duration of MV in the NAVA mode was 2.64 days lower than other CMVs (MD = -2.64; 95% CI, -4.88 to -0.41; P = 0.02), and NAVA may decrease the ICU mortality (OR =0.60; 95% CI, 0.42 to 0.86; P = 0.006). There was no statistically significant difference in the incidence of ventilator-associated pneumonia, pH, and PaCO2 between NAVA and other MV modes.

Conclusions

Our study suggests that NAVA ameliorates the synchronization of patient-ventilator and improves the important clinical outcomes of patients with ARF compared with CMV modes.