Driving Pressure, Elastance, and Outcomes in a Real-World Setting: A Bi-Center Analysis of Electronic Health Record Data

Lung Protective Ventilation Adherence and Outcomes for Patients With COVID-19 Acute Respiratory Distress Syndrome Treated in an Intermediate Care Unit Repurposed to ICU Level of Care

OBJECTIVE

During the COVID-19 pandemic, some centers converted intermediate care units (IMCUs) to COVID-19 ICUs (IMCU/ICUs). In this study, we compared adherence to lung protective ventilation (LPV) and outcomes for patients with COVID-19-related acute respiratory distress syndrome (ARDS) treated in an IMCU/ICU versus preexisting medical ICUs (MICUs).

DESIGN

Retrospective observational study using electronic medical record data.

SETTING

Two academic medical centers from March 2020 to September 2020 (period 1) and October 2020 to May 2021 (period 2), which capture the first two COVID-19 surges in this health system.

PATIENTS

Adults with COVID-19 receiving invasive mechanical ventilation who met ARDS oxygenation criteria (Pao2/Fio2 ≤ 300 mm Hg or Spo2/Fio2 ≤ 315).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We defined LPV adherence as the percent of the first 48 hours of mechanical ventilation that met a restrictive definition of LPV of, tidal volume/predicted body weight (Vt/PBW) less than or equal to 6.5 mL/kg and plateau pressure (Pplat) less than or equal to 30 cm H2o. In an expanded definition, we added that if Pplat is greater than 30 cm H2o, Vt/PBW had to be less than 6.0 mL/kg. Using the restricted definition, period 1 adherence was lower among 133 IMCU/ICU versus 199 MICU patients (92% [95% CI, 50-100] vs. 100% [86-100], p = 0.05). Period 2 adherence was similar between groups (100% [75-100] vs. 95% CI [65-100], p = 0.68). A similar pattern was observed using the expanded definition. For the full study period, the adjusted hazard of death at 90 days was lower in IMCU/ICU versus MICU patients (hazard ratio [HR] 0.73 [95% CI, 0.55-0.99]), whereas ventilator liberation by day 28 was similar between groups (adjusted subdistribution HR 1.09 [95% CI, 0.85-1.39]).

CONCLUSIONS

In patients with COVID-19 ARDS treated in an IMCU/ICU, LPV adherence was similar to, and observed survival better than those treated in preexisting MICUs. With adequate resources, protocols, and staffing, IMCUs provide an effective source of additional ICU capacity for patients with acute respiratory failure.

Driving pressure in mechanical ventilation: A review

Driving pressure (∆P) is a core therapeutic component of mechanical ventilation (MV). Varying levels of ∆P have been employed during MV depending on the type of underlying pathology and severity of injury. However, ∆P levels have also been shown to closely impact hard endpoints such as mortality. Considering this, conducting an in-depth review of ∆P as a unique, outcome-impacting therapeutic modality is extremely important. There is a need to understand the subtleties involved in making sure ∆P levels are optimized to enhance outcomes and minimize harm. We performed this narrative review to further explore the various uses of ∆P, the different parameters that can affect its use, and how outcomes vary in different patient populations at different pressure levels. To better utilize ∆P in MV-requiring patients, additional large-scale clinical studies are needed.

Setting positive end-expiratory pressure: does the 'best compliance' concept really work?

PURPOSE OF REVIEW

Determining the optimal positive end-expiratory pressure (PEEP) setting remains a central yet debated issue in the management of acute respiratory distress syndrome (ARDS).The 'best compliance' strategy set the PEEP to coincide with the peak respiratory system compliance (or 2 cmH 2 O higher) during a decremental PEEP trial, but evidence is conflicting.

RECENT FINDINGS

The physiological rationale that best compliance is always representative of functional residual capacity and recruitment has raised serious concerns about its efficacy and safety, due to its association with increased 28-day all-cause mortality in a randomized clinical trial in ARDS patients.Moreover, compliance measurement was shown to underestimate the effects of overdistension, and neglect intra-tidal recruitment, airway closure, and the interaction between lung and chest wall mechanics, especially in obese patients. In response to these concerns, alternative approaches such as recruitment-to-inflation ratio, the nitrogen wash-in/wash-out technique, and electrical impedance tomography (EIT) are gaining attention to assess recruitment and overdistention more reliably and precisely.

SUMMARY

The traditional 'best compliance' strategy for determining optimal PEEP settings in ARDS carries risks and overlooks some key physiological aspects. The advent of new technologies and methods presents more reliable strategies to assess recruitment and overdistention, facilitating personalized approaches to PEEP optimization.

Mechanical ventilation in patients with acute respiratory distress syndrome: current status and future perspectives

INTRODUCTION

Although there has been extensive research on mechanical ventilation for acute respiratory distress syndrome (ARDS), treatment remains mainly supportive. Recent studies and new ventilatory modes have been proposed to manage patients with ARDS; however, the clinical impact of these strategies remains uncertain and not clearly supported by guidelines. The aim of this narrative review is to provide an overview and update on ventilatory management for patients with ARDS.

AREAS COVERED

This article reviews the literature regarding mechanical ventilation in ARDS. A comprehensive overview of the principal settings for the ventilator parameters involved is provided as well as a report on the differences between controlled and assisted ventilation. Additionally, new modes of assisted ventilation are presented and discussed. The evidence concerning rescue strategies, including recruitment maneuvers and extracorporeal membrane oxygenation support, is analyzed. PubMed, EBSCO, and the Cochrane Library were searched up until June 2023, for relevant literature.

EXPERT OPINION

Available evidence for mechanical ventilation in cases of ARDS suggests the use of a personalized mechanical ventilation strategy. Although promising, new modes of assisted mechanical ventilation are still under investigation and guidelines do not recommend rescue strategies as the standard of care. Further research on this topic is required.