Early prone positioning in acute respiratory distress syndrome related to COVID-19: a propensity score analysis from the multicentric cohort COVID-ICU network-the ProneCOVID study

Effect of early and later prone positioning on outcomes in invasively ventilated COVID-19 patients with acute respiratory distress syndrome: analysis of the prospective COVID-19 critical care consortium cohort study

BACKGROUND

Prone positioning of patients with COVID-19 undergoing invasive mechanical ventilation (IMV) is widely used, but evidence of efficacy remains sparse. The COVID-19 Critical Care Consortium has generated one of the largest global datasets on the management and outcomes of critically ill COVID-19 patients. This prospective cohort study investigated the association between prone positioning and mortality and in particular focussed on timing of treatment.

METHODS

We investigated the incidence, demographic profile, management and outcomes of proned patients undergoing IMV for COVID-19 in the study. We compared outcomes between patients prone positioned within 48 h of IMV to those (i) never proned, and (ii) proned only after 48 h.

RESULTS

3131 patients had data on prone positioning, 1482 (47%) were never proned, 1034 (33%) were proned within 48 h and 615 (20%) were proned only after 48 h of commencement of IMV. 28-day (hazard ratio 0.82, 95% confidence interval [CI] 0.68, 0.98, p = 0.03) and 90-day (hazard ratio 0.81, 95% CI 0.68, 0.96, p = 0.02) mortality risks were lower in those patients proned within 48 h of IMV compared to those never proned. However, there was no evidence for a statistically significant association between prone positioning after 48 h with 28-day (hazard ratio 0.93, 95% CI 0.75, 1.14, p = 0.47) or 90-day mortality (hazard ratio 0.95, 95% CI 0.78, 1.16, p = 0.59).

CONCLUSIONS

Prone positioning is associated with improved outcomes in patients with COVID-19, but timing matters. We found no association between later proning and patient outcome.

Is prone positioning a valid intervention for ARDS in the deployed intensive care unit?

Prone positioning is an intervention used for patients with acute respiratory distress syndrome (ARDS) whose hypoxia is worsening despite conventional treatment. Previously used infrequently, it became an important treatment escalation strategy for hypoxia during the COVID-19 pandemic. Current evidence for prone positioning suggests increased survivability in intubated patients with moderate to severe ARDS who are prone for >12 hours a day. As a relatively low-cost, low-tech intervention with a growing evidence base, the viability of prone positioning in the deployed land environment is considered in this article. The practical technique of prone positioning is easy to teach to healthcare staff experienced in manual handling. However, it requires significant resources, in particular staff numbers, and time to execute and maintain, and necessitates a pressure-minimising mattress. Additionally, staff are placed at increased risk of musculoskeletal injuries and potential exposure to aerosolised microbes if there is a disconnection of the breathing system. We conclude that in the deployed 2/1/2/12 facility (or larger), with access to higher staff numbers and high-specification mattresses, prone positioning is a valid escalation technique for intubated hypoxic patients with ARDS. However, in smaller facilities where resources are constrained, its implementation is unlikely to be achievable.

Does Helping Others Always Benefit Health? Longitudinal Evidence on the Relationship between Helping Behavior and Depression: The Mediating Role of Life Satisfaction and the Moderating Effect of IADL

Background

This study aims to explore whether helping behavior is always beneficial for alleviating depression or if there is a "moderation is the key" effect.

Materials and Methods

This study focused on a sample of 7,436 participants from the China Health and Retirement Longitudinal Study (CHARLS). The 10-item Center for Epidemiologic Studies Depression Scale (CESD-10) was used to identify the presence of depression. Linear mixed model and Quasi-Bayesian estimation methods were used to explore the mediating role of life satisfaction in the relationship between helping behavior and depression, as well as the moderating effects of the instrumental activity of daily living (IADL). Additionally, we employed the Johnson-Neyman technique to visualize the moderating effect of IADL.

Results

Helping behavior shows a negative correlation with depression (B = -0.170, p = 0.020), where life satisfaction fully mediates this relationship (effect = -0.055, 95% confidence interval = -0.088 to -0.022). Moreover, the association between helping behavior and life satisfaction is moderated by IADL (B = -0.047, p < 0.001). Specifically, when IADL is below 0.56, helping behavior positively impacts life satisfaction. In contrast, when IADL exceeds 1.99, helping behavior has a detrimental effect on life satisfaction.

Conclusions

This study highlights the significant positive impact of helping behavior on depression alleviation, which is achieved by increasing life satisfaction. Notably, although helping behavior has positive effects on individuals, not everyone can benefit directly from it. Only those without functional limitations are more likely to experience the benefits of such behavior. Therefore, when policymakers and researchers develop strategies to encourage individuals in helping behavior to combat depression, they should consider two key approaches. First, life satisfaction should be used as an important indicator in the treatment of depression, allowing for timely adjustments to ensure the effectiveness and individualization of treatment plans. Second, the principle of "moderation is the key" should be prioritized, ensuring that helping behavior can maximize its benefits and help individuals emerge from the shadows of depression.

Impact of intensive prone position therapy on outcomes in intubated patients with ARDS related to COVID-19

BACKGROUND

Previous retrospective research has shown that maintaining prone positioning (PP) for an average of 40 h is associated with an increase of survival rates in intubated patients with COVID-19-related acute respiratory distress syndrome (ARDS). This study aims to determine whether a cumulative PP duration of more than 32 h during the first 2 days of intensive care unit (ICU) admission is associated with increased survival compared to a cumulative PP duration of 32 h or less.

METHODS

This study is an ancillary analysis from a previous large international observational study involving intubated patients placed in PP in the first 48 h of ICU admission in 149 ICUs across France, Belgium and Switzerland. Given that PP is recommended for a 16-h daily duration, intensive PP was defined as a cumulated duration of more than 32 h during the first 48 h, whereas standard PP was defined as a duration equal to or less than 32 h. Patients were followed-up for 90 days. The primary outcome was mortality at day 60. An Inverse Probability Censoring Weighting (IPCW) Cox model including a target emulation trial method was used to analyze the data.

RESULTS

Out of 2137 intubated patients, 753 were placed in PP during the first 48 h of ICU admission. The intensive PP group (n = 79) had a median PP duration of 36 h, while standard PP group (n = 674) had a median of 16 h during the first 48 h. Sixty-day mortality rate in the intensive PP group was 39.2% compared to 38.7% in the standard PP group (p = 0.93). Twenty-eight-day and 90-day mortality as well as the ventilator-free days until day 28 were similar in both groups. After IPCW, there was no significant difference in mortality at day 60 between the two-study groups (HR 0.95 [0.52-1.74], p = 0.87 and HR 1.1 [0.77-1.57], p = 0.61 in complete case analysis or in multiple imputation analysis, respectively).

CONCLUSIONS

This secondary analysis of a large multicenter European cohort of intubated patients with ARDS due to COVID-19 found that intensive PP during the first 48 h did not provide a survival benefit compared to standard PP.

Rapid triage and transfer system for patients with proven Covid-19 at emergency department

BACKGROUND

COVID-19 is a viral disease notorious for frequent worldwide outbreaks. It is difficult to control, thereby resulting in overload of the healthcare system. A possible solution to prevent overcrowding is rapid triage of patients, which makes it possible to focus care on the high-risk patients and minimize the impact of crowding on patient prognosis.

METHODS

The triage algorithm assessed self-sufficiency, oximetry, systolic blood pressure, and the Glasgow coma scale. Compliance with the triage protocol was defined as fulfillment of all protocol steps, including assignment of the correct level of care. Triage was considered successful if there was no change in the scope of care (e.g., unscheduled hospital admission, transfer to different level of care) or if there was unexpected death within 48 hours.

RESULTS

A total of 929 patients were enrolled in the study. Triage criteria were fulfilled in 825 (88.8%) patients. Within 48 hours, unscheduled hospital admission, transfer to different level of care, or unexpected death occurred in 56 (6.0%), 6 (0.6%), and 5 (0.5%) patients, respectively. The risk of unscheduled hospital admission or transfer to different level of care was significantly increased if triage criteria were not fulfilled [13.1% vs. 76.1%, RR 5.8 (3.8-8.3), p < 0.001; 0.5% vs. 5.2%, RR 11.4 (2.3-57.7), p = 0.036, respectively].

CONCLUSION

The proposed algorithm for triage of patients with proven COVID-19 is a simple, fast, and reliable tool for rapid sorting for outpatient treatment, hospitalization on a standard ward, or assignment to an intensive care unit.

[Ventilatory management of SARS-CoV-2 acute respiratory failure]

COVID-19 pneumonia presents several particularities in its clinical presentation (cytokine storm, silent hypoxemia, thrombo-embolic risk) and may lead to a number of acute respiratory distress syndrome (ARDS) phenotypes. While the optimal oxygenation strategy in cases of hypoxemic acute respiratory failure (ARF) is still under debate, ventilatory management of COVID-19-related ARF has confirmed the efficacy of high-flow oxygen therapy and restored interest in other ventilatory approaches such as continuous positive airway pressure (CPAP) and noninvasive ventilation involving a helmet, which due to patient overflow are sometimes implemented outside of critical care units. However, further studies are still needed to determine which patients should be given which oxygenation technique, and under which conditions they require invasive mechanical ventilation, given that delayed initiation potentially burdens prognosis. During invasive mechanical ventilation, ventral decubitus and extracorporeal membrane oxygenation have become increasingly prevalent. While innovative therapies such as awake prone position or lung transplantation have likewise been developed, their indications, modalities and efficacy remain to be determined.

Physical function and mental health trajectories in COVID-19 patients following invasive mechanical ventilation: a prospective observational study

This prospective observational cohort study was performed to investigate the physical function and mental health trajectories of novel coronavirus disease 2019 (COVID-19) patients requiring invasive mechanical ventilation (IMV) after discharge from the intensive care unit (ICU). The study population consisted of 64 patients (median age, 60 years; 85.9% male; median IMV duration, 9 days). At ICU discharge, 28.1% of the patients had Medical Research Council (MRC) sum score < 48 points, and prolonged IMV was significantly associated with lower MRC sum score and handgrip strength. Symptoms were similar between groups at ICU discharge, and the symptoms most commonly reported as moderate-to-severe were impaired well-being (52%), anxiety (43%), tiredness (41%), and depression (35%). Although muscle strength and mobility status were significantly improved after ICU discharge, Edmonton Symptom Assessment System score did not improve significantly in the prolonged IMV group. EuroQol five-dimension five-level summary index was significantly lower in the prolonged than short IMV group at 6 months after ICU discharge. We found substantial negative physical function and mental health consequences in the majority of surviving COVID-19 patients requiring IMV, with prolonged period of IMV showing greater negative effects not only immediately but also at 6 months after discharge from the ICU.

Mechanical Power Delivered by Noninvasive Ventilation Contributes to Physio-Anatomical and Clinical Responses to Early Versus Late Proning in COVID-19 Pneumonia

OBJECTIVES

To study: 1) the effect of prone position (PP) on noninvasive ventilation (NIV)-delivered mechanical power (MP) and 2) the impact of MP on physio-anatomical and clinical responses to early versus late PP in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pneumonia.

DESIGN

Nonrandomized trial with inverse probability of treatment weighted-matched groups.

SETTING

HUMANITAS Gradenigo Sub-ICU.

PATIENTS

One hundred thirty-eight SARS-CoV-2 pneumonia patients with moderate-to-severe acute hypoxemic respiratory failure (Pa o2 /F io2 ratio < 200 mm Hg) receiving NIV from September 1, 2020, to February 28, 2021 (Ethics approval: ISRCTN23016116).

INTERVENTIONS

Early PP or late PP or supine position.

MEASUREMENTS AND MAIN RESULTS

Respiratory parameters were hourly recorded. Time-weighted average MP values were calculated for each ventilatory session. Gas exchange parameters and ventilatory ratio (VR) were measured 1 hour after each postural change. Lung ultrasonographic scores and circulating biomarkers were assessed daily. MP delivered during the initial 24 hours of NIV (MP [first 24 hr]) was the primary exposure variable. Primary outcomes: 28-day endotracheal intubation and death. Secondary outcomes: oxygen-response, C o2 -response, ultrasonographic, and systemic inflammatory biomarker responses after 24 hours of NIV. Fifty-eight patients received early PP + NIV, 26 late PP + NIV, and 54 supine NIV. Early PP group had lower 28-day intubation and death than late PP (hazard ratio [HR], 0.35; 95% CI, 0.19-0.69 and HR, 0.26; 95% CI, 0.07-0.67, respectively) and supine group. In Cox multivariate analysis, (MP [first 24 hr]) predicted 28-day intubation (HR, 1.70; 95% CI, 1.25-2.09; p = 0.009) and death (HR, 1.51; 95% CI, 1.19-1.91; p = 0.007). Compared with supine position, PP was associated with a 35% MP reduction. VR, ultrasonographic scores, and inflammatory biomarkers improved after 24 hours of NIV in the early PP, but not in late PP or supine group. A MP (first 24 hr) greater than or equal to 17.9 J/min was associated with 28-day death (area under the curve, 0.92; 95% CI, 0.88-0.96; p < 0.001); cumulative hours of MP greater than or equal to 17.9 J/min delivered before PP initiation attenuated VR, ultrasonographic, and biomarker responses to PP.

CONCLUSIONS

MP delivered by NIV during initial 24 hours predicts clinical outcomes. PP curtails MP, but cumulative hours of NIV with MP greater than or equal to 17.9 J/min delivered before PP initiation attenuate the benefits of PP.

Adaptation and Uncertainty: A Qualitative Examination of Provider Experiences With Prone Positioning for Intubated Patients With COVID-19 ARDS

BACKGROUND

Prone positioning was widely adopted for use in patients with ARDS from COVID-19. However, proning was also delivered in ways that differed from historical evidence and practice. In implementation research, these changes are referred to as adaptations, and they occur constantly as evidence-based interventions are used in real-world practice. Adaptations can alter the delivered intervention, impacting patient and implementation outcomes.

RESEARCH QUESTION

How have clinicians adapted prone positioning to COVID-19 ARDS, and what uncertainties remain regarding optimal proning use?

STUDY DESIGN AND METHODS

We conducted a qualitative study using semi-structured interviews with ICU clinicians from two hospitals in Baltimore, MD, from February to July 2021. We interviewed physicians (MDs), registered nurses (RNs), respiratory therapists (RTs), advanced practice providers (APPs), and physical therapists (PTs) involved with proning mechanically ventilated patients with COVID-19 ARDS. We used thematic analysis of interviews to classify proning adaptations and clinician uncertainties about best practice for prone positioning.

RESULTS

Forty ICU clinicians (12 MDs, 4 APPs, 12 RNs, 7 RTs, and 5 PTs) were interviewed. Clinicians described several adaptations to the practice of prone positioning, including earlier proning initiation, extended duration of proning sessions, and less use of concomitant neuromuscular blockade. Clinicians expressed uncertainty regarding the optimal timing of initiation and duration of prone positioning. This uncertainty was viewed as a driver of practice variation. Although prescribers intended to use less deep sedation and paralysis in proned patients compared with historical evidence and practice, this raised concerns regarding patient comfort and safety amongst RNs and RTs.

INTERPRETATION

Prone positioning in patients with COVID-19 ARDS has been adapted from historically described practice. Understanding the impact of these adaptations on patient and implementation outcomes and addressing clinician uncertainties are priority areas for future research to optimize the use of prone positioning.

COVID-19 and Hospital-Acquired Pressure Injuries: A Systematic Review

OBJECTIVE

To investigate the relationship between COVID-19-related variables and hospital-acquired pressure injury (HAPI) incidence.

DATA SOURCES

The authors searched four databases: Cochrane, MEDLINE, EMBASE, and CINAHL. The literature search contained key terms such as "COVID-19," "hospital-acquired pressure injuries," "pressure ulcer," "pressure injury," "decubitus ulcer," and "hospitalization."

STUDY SELECTION

The systematic search of the literature identified 489 publications that matched the inclusion criteria. Articles were included in the review if they were peer-reviewed publications that reported HAPI incidence for patients who were hospitalized and COVID-19 positive. Two reviewers performed the screen simultaneously, and 19 publications were included.

DATA EXTRACTION

Two reviewers followed a standardized extraction form that included study and patient characteristics, COVID-19 status, HAPI characteristics, prone positioning, length of hospitalization, and HAPI prevention and treatment strategies.

DATA SYNTHESIS

The authors carried out a narrative synthesis of the extracted data because the data obtained were too heterogeneous for meta-analysis. The primary outcome was HAPI incidence.

CONCLUSIONS

This review identified that HAPI incidence was high among men who were COVID-19 positive, had longer hospital stays, experienced prone positioning, and had care teams without a skin and wound care expert. Future research should use more robust methodology and focus on quantitative modeling to iteratively improve inpatient HAPI guidelines.

Factors related to COVID-19 mortality among three Swedish intensive care units-A retrospective study

BACKGROUND

Mortality due to acute hypoxemic respiratory failure (AHRF) in patients with coronavirus disease-19 (COVID-19) differs across units, regions, and countries. These variations may be attributed to several factors, including comorbidities, acute physiological derangement, disease severity, treatment, ethnicity, healthcare system strain, and socioeconomic status. This study aimed to explore the features of patient characteristics, clinical management, and staffing that may be related to mortality among three intensive care units (ICUs) within the same hospital system in South Sweden.

METHODS

We retrospectively analyzed ICU patients with COVID-19 and AHRF in Region Jönköping County, Sweden. The primary outcome was the 90-day mortality rate. We used univariate and multivariable logistic regression analyses to investigate the relationship of predictors with outcomes.

RESULTS

Between March 15, 2020, and May 31, 2021, 331 patients with AHRF and COVID-19 were admitted to the three ICUs. There were differences in disease severity, treatments, process-related factors, and socioeconomic factors between the units. These factors were related to 90-day mortality. After multivariable adjustment, age, severity of acute respiratory distress syndrome, and the number of nurses per ICU-bed independently predicted 90-day mortality.

CONCLUSION

Age, disease severity, and nurse staffing, but not treatment or socioeconomic status, were independently associated with 90-day mortality among critically ill patients with AHRF due to COVID-19. We also identified variations in care related processes, which may be a modifiable risk factor and warrants future investigation.

Mechanical power normalized to aerated lung predicts noninvasive ventilation failure and death and contributes to the benefits of proning in COVID-19 hypoxemic respiratory failure

Background

Concern exists that noninvasive ventilation (NIV) may promote ventilation-induced lung injury(VILI) and worsen outcome in acute hypoxemic respiratory failure (AHRF). Different individual ventilatory variables have been proposed to predict clinical outcomes, with inconsistent results.Mechanical power (MP), a measure of the energy transfer rate from the ventilator to the respiratory system during mechanical ventilation, might provide solutions for this issue in the framework of predictive, preventive and personalized medicine (PPPM). We explored (1) the impact of ventilator-delivered MP normalized to well-aerated lung (MP_WAL) on physio-anatomical and clinical responses to NIV in COVID-19-related AHRF and (2) the effect of prone position(PP) on MP_WAL.

Methods

We analyzed 216 noninvasively ventilated COVID-19 patients (108 patients receiving PP + NIV and 108 propensity score-matched patients receiving supine NIV) with moderate-to-severe(paO2/FiO2 ratio < 200) AHRF enrolled in the PRO-NIV controlled non-randomized study (ISRCTN23016116).Quantification of differentially aerated lung volumes by lung ultrasonography (LUS) was validated against CT scans. Respiratory parameters were hourly recorded, ABG were performed 1 h after each postural change. Time-weighed average values of ventilatory variables, including MP_WAL, and gas exchange parameters (paO2/FiO2 ratio, dead space indices) were calculated for each ventilatory session. LUS and circulating biomarkers were assessed daily.

Results

Compared with supine position, PP was associated with a 34% MP_WAL reduction, attributable largely to an absolute MP reduction and secondly to an enhanced lung reaeration.Patients receiving a high MP_WAL during the 1^st 24 h of NIV [MP_WAL(day 1)] had higher 28-d NIV failure (HR = 4.33,95%CI:3.09 - 5.98) and death (HR = 5.17,95%CI: 3.01 - 7.35) risks than those receiving a low MP_WAL(day 1).In Cox multivariate analyses, MP_WAL(day 1) remained independently associated with 28-d NIV failure (HR = 1.68,95%CI:1.15-2.41) and death (HR = 1.69,95%CI:1.22-2.32).MP_WAL(day 1) outperformed other power measures and ventilatory variables as predictor of 28-d NIV failure (AUROC = 0.89;95%CI:0.85-0.93) and death (AUROC = 0.89;95%CI:0.85-0.94).MP_WAL(day 1) predicted also gas exchange, ultrasonographic and inflammatory biomarker responses, as markers of VILI, on linear multivariate analysis.

Conclusions

In the framework of PPPM, early bedside MP_WAL calculation may provide added value to predict response to NIV and guide subsequent therapeutic choices i.e. prone position adoption during NIV or upgrading to invasive ventilation, to reduce hazardous MP_WAL delivery, prevent VILI progression and improve clinical outcomes in COVID-19-related AHRF.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13167-023-00325-5.

Is COVID-19 different from other causes of acute respiratory distress syndrome?

Coronavirus disease 2019 (COVID-19) pneumonia can lead to acute hypoxemic respiratory failure. When mechanical ventilation is needed, almost all patients with COVID-19 pneumonia meet the criteria for acute respiratory distress syndrome (ARDS). The question of the specificities of COVID-19-associated ARDS compared to other causes of ARDS is of utmost importance, as it may justify changes in ventilatory strategies. This review aims to describe the pathophysiology of COVID-19-associated ARDS and discusses whether specific ventilatory strategies are required in these patients.

COVID-19 and Hospital-Acquired Pressure Injuries: A Systematic Review

OBJECTIVE

To investigate the relationship between COVID-19 related variables and hospital-acquired pressure injuries (HAPI) incidence.

DATA SOURCES

The authors searched four databases: Cochrane, MEDLINE, EMBASE, and CINAHL. The literature search contained key terms such as COVID-19, hospital-acquired pressure injuries, pressure ulcer, pressure injury, decubitus ulcer, and hospitalization.

STUDY SELECTION

The systematic search of the literature identified 489 publications that matched the inclusion criteria. This included peer-reviewed publications that reported HAPI incidence for patients who were hospitalized and COVID-19 positive. Two reviewers performed the screen simultaneously and 19 publications were included.

DATA EXTRACTION

Two reviewers followed a standardized extraction form that included study and patient characteristics, COVID-19 status, HAPI characteristics, prone positioning, length of hospitalization, and HAPI prevention and treatment strategies.

DATA SYNTHESIS

A narrative synthesis of the extracted data was carried out because the data obtained were too heterogeneous for meta-analysis. The primary outcome was HAPI incidence.

CONCLUSIONS

This review identified that HAPI incidence was high among men who were COVID-19 positive, had longer hospital stays, experienced prone positioning, and had care teams without a skin and wound care expert. Future research should employ more robust methodology and focus on quantitative modeling to iteratively improve in-patient HAPI guidelines.

Factors Influencing the Implementation of Prone Positioning during the COVID-19 Pandemic: A Qualitative Study

Rationale: The adoption of prone positioning for patients with acute respiratory distress syndrome (ARDS) has historically been poor. However, in mechanically ventilated patients with coronavirus disease (COVID-19) ARDS, proning has increased. Understanding the factors influencing this change is important for further expanding and sustaining the use of prone positioning in appropriate clinical settings. Objectives: To characterize factors influencing the implementation of prone positioning in mechanically ventilated patients with COVID-19 ARDS. Methods: We conducted a qualitative study using semistructured interviews with 40 intensive care unit (ICU) team members (physicians, nurses, advanced practice providers, respiratory therapists, and physical therapists) working at two academic hospitals. We used the Consolidated Framework for Implementation Research, a widely used implementation science framework outlining important features of implementation, to structure the interview guide and thematic analysis of interviews. Results: ICU clinicians reported that during the COVID-19 pandemic, proning was viewed as standard early therapy for COVID-19 ARDS rather than salvage therapy for refractory hypoxemia. By caring for large volumes of proned patients, clinicians gained increased comfort with proning and now view proning as a low-risk, high-benefit intervention. Within ICUs, adequate numbers of trained staff members, increased team agreement around proning, and the availability of specific equipment (e.g., to limit pressure injuries) facilitated greater proning use. Hospital-level supports included proning teams, centralized educational resources specific to the management of COVID-19 (including a recommendation for prone positioning), and an electronic medical record proning order. Important implementation processes included informal dissemination of best practices through on-the-job learning and team interactions during routine bedside care. Conclusions: The implementation of prone positioning for COVID-19 ARDS took place in the context of evolving clinician viewpoints and ICU team cultures. Proning was facilitated by hospital support and buy-in and leadership from bedside clinicians. The successful implementation of prone positioning during the COVID-19 pandemic may serve as a model for the implementation of other evidence-based therapies in critical care.

Effect of prone positioning on end-expiratory lung volume, strain and oxygenation change over time in COVID-19 acute respiratory distress syndrome: A prospective physiological study

Background

Prone position (PP) is a recommended intervention in severe classical acute respiratory distress syndrome (ARDS). Changes in lung resting volume, respiratory mechanics and gas exchange during a 16-h cycle of PP in COVID-19 ARDS has not been yet elucidated.

Methods

Patients with severe COVID-19 ARDS were enrolled between May and September 2021 in a prospective cohort study in a University Teaching Hospital. Lung resting volume was quantitatively assessed by multiple breath nitrogen wash-in/wash-out technique to measure the end-expiratory lung volume (EELV). Timepoints included the following: Baseline, Supine Position (S1); start of PP (P0), and every 4-h (P4; P8; P12) until the end of PP (P16); and Supine Position (S2). Respiratory mechanics and gas exchange were assessed at each timepoint.

Measurements and main results

40 mechanically ventilated patients were included. EELV/predicted body weight (PBW) increased significantly over time. The highest increase was observed at P4. The highest absolute EELV/PBW values were observed at the end of the PP (P16 vs S1; median 33.5 ml/kg [InterQuartileRange, 28.2-38.7] vs 23.4 ml/kg [18.5-26.4], p < 0.001). Strain decreased immediately after PP and remained stable between P4 and P16. PaO2/FiO2 increased during PP reaching the highest level at P12 (P12 vs S1; 163 [138-217] vs 81 [65-97], p < 0.001). EELV/PBW, strain and PaO2/FiO2 decreased at S2 although EELV/PBW and PaO2/FiO2 were still significantly higher as compared to S1. Both absolute values over time and changes of strain and PaO2/FiO2 at P16 and S2 versus S1 were strongly associated with EELV/PBW levels.

Conclusion

In severe COVID-19 ARDS, EELV steadily increased over a 16-h cycle of PP peaking at P16. Strain gradually decreased, and oxygenation improved over time. Changes in strain and oxygenation at the end of PP and back to SP were strongly associated with changes in EELV/PBW. Whether the change in EELV and oxygenation during PP may play a role on outcomes in COVID-ARDS deserves further investigation.

Clinical trial registration

[www.ClinicalTrials.gov], identifier [NCT04818164].