Factors for success of awake prone positioning in patients with COVID-19-induced acute hypoxemic respiratory failure: analysis of a randomized controlled trial

A randomised clinical trial of awake prone positioning in COVID-19 suspects with acute hypoxemic respiratory failure

Background

Awake prone position (APP) has been reported to improve oxygenation in patients with COVID-19 disease and to reduce the requirement for invasive mechanical ventilation for patients requiring support with high flow nasal cannula. There is conflicting data for patients requiring lower-level oxygen support.

Research question

Does APP reduce escalation of oxygen support in COVID-19 patients requiring supplementary oxygen?The primary outcome was defined as an escalation of oxygen support from simple supplementary oxygen (NP, HM, NRB) to NIV (CPAP or BiPAP), HFNC or IMV; OR from NIV (CPAP or BiPAP) or HFNC to IMV by day30.

Study design

Two center, prospective, non-blind, randomised controlled trial. Patients with confirmed or suspected COVID-19 pneumonia requiring ≥ 5 liters/min oxygen to maintain saturations ≥ 94 % were randomised to either APP or control group. The APP group received a 3-h APP session three times per day for three days.

Results

Between 9 May and July 13, 2021, 89 adults were screened and 61 enrolled, 31 to awake prone position and 30 controls. There was no difference in the primary outcome, 7 (22.6 %) patients randomised to APP and 9 (30.0 %) controls required escalation of oxygen support (OR 0.68 (0.22-2.14), P = 0.51). There were no differences in any secondary outcomes, in APP did not improve oxygenation.

Interpretation

In COVID-19 patients, the use of APP did not prevent escalation of oxygen support from supplementary to invasive or non-invasive ventilation or improve patient respiratory physiology.

Trial registration

NCT04853979 (clinicaltrials.gov).

Coronavirus Disease 2019: Past, Present, and Future

Severe acute respiratory syndrome coronavirus 2 is one of the most impactful diseases experienced in the past century. While the official national health emergency concluded in May of 2023, coronavirus disease 2019 (COVID-19) continues to mutate. As the summer of 2023, all countries were experiencing a new surge of cases from the EG.5 Omicron variant. Additionally, a new genetically distinct Omicron descendant BA2.86 had been detected in multiple countries including the United States. This article seeks to offer lessons learned from the pandemic, summarize best evidence for current management of patients with COVID-19, and give insights into future directions with this disease.

Conscious prone positioning in nonintubated COVID-19 patients with acute respiratory distress syndrome: systematic review and meta-analysis

OBJECTIVE

To systematically review the effect of the prone position on endotracheal intubation and mortality in nonintubated COVID-19 patients with acute respiratory distress syndrome.

METHODS

We registered the protocol (CRD42021286711) and searched for four databases and gray literature from inception to December 31, 2022. We included observational studies and clinical trials. There was no limit by date or the language of publication. We excluded case reports, case series, studies not available in full text, and those studies that included children < 18-years-old.

RESULTS

We included ten observational studies, eight clinical trials, 3,969 patients, 1,120 endotracheal intubation events, and 843 deaths. All of the studies had a low risk of bias (Newcastle-Ottawa Scale and Risk of Bias 2 tools). We found that the conscious prone position decreased the odds of endotracheal intubation by 44% (OR 0.56; 95%CI 0.40 - 0.78) and mortality by 43% (OR 0.57; 95%CI 0.39 - 0.84) in nonintubated COVID-19 patients with acute respiratory distress syndrome. This protective effect on endotracheal intubation and mortality was more robust in those who spent > 8 hours/day in the conscious prone position (OR 0.43; 95%CI 0.26 - 0.72 and OR 0.38; 95%CI 0.24 - 0.60, respectively). The certainty of the evidence according to the GRADE criteria was moderate.

CONCLUSION

The conscious prone position decreased the odds of endotracheal intubation and mortality, especially when patients spent over 8 hours/day in the conscious prone position and treatment in the intensive care unit. However, our results should be cautiously interpreted due to limitations in evaluating randomized clinical trials, nonrandomized clinical trials and observational studies. However, despite systematic reviews with meta-analyses of randomized clinical trials, we must keep in mind that these studies remain heterogeneous from a clinical and methodological point of view.

Optimal timing for awake prone positioning in Covid-19 patients: Insights from an observational study from two centers

BACKGROUND

The widespread application and interest in awake prone positioning stems from its ease and availability and its ability to enhance patients' oxygenation. Nevertheless, due to the absence of consensus over the regimen of awake prone positioning, the efficacy of awake prone positioning remains uncertain.

OBJECTIVE

To explore the optimal regimen for awake prone positioning, including the timing of initiation, ideal daily duration, and strategies for improving patient comfort and encouraging adherence.

DESIGN

Retrospective observational study.

SETTING(S)

Two university-affiliated hospitals in Shanghai.

PARTICIPANTS

Between December 2022 and February 2023, a total of 475 patients with COVID-19-related pneumonia who received awake prone positioning were observed.

METHODS

The data were collected from the hospital's electronic medical record system. The differentiation efficiency of peripheral blood oxygen saturation [SpO2]:fractional oxygen concentration in inspired air [FiO2] ratio at first awake prone positioning for different outcomes was tested by the area under the receiver operating characteristic curve. The Cox proportional hazard regression model was used to analyze the relationship between time to occurrence of 28-day outcomes and collected variables. Kaplan-Meier curves were plotted with the percentage of 28-day outcomes according to the SpO2:FiO2 ratio at first awake prone positioning after controlling covariates through Cox regression.

RESULTS

The best efficiency in predicting patient outcomes was achieved when the cutoff SpO2:FiO2 ratio at first awake prone positioning was 200. Patients with a reduced SpO2:FiO2 ratio (≤200) experienced more adverse respiratory outcomes (RR = 5.42, 95%CI [3.35, 8.76], p < 0·001) and higher mortality (RR = 16.64, 95%CI [5.53, 50.13], p < 0.001). Patients with a SpO2:FiO2 ratio of ≥200 at first awake prone positioning, longer duration between first awake prone positioning and admission, more awake prone positioning days, and better awake prone positioning completion were significantly protected from 28-day adverse respiratory outcomes and mortality.

CONCLUSIONS

Initiating awake prone positioning with a SpO2:FiO2 ratio exceeding 200, increasing the number of awake prone positioning days, prolonging the time between first awake prone positioning and admission, and achieving better completion of awake prone positioning were found to be significantly associated with reduced adverse respiratory outcomes and mortality.

REGISTRATION

ClinicalTrials.gov; No.: NCT05795751; URL: www.

CLINICALTRIALS

gov.

Lung impedance changes during awake prone positioning in COVID-19. A non-randomized cross-over study

BACKGROUND

The effects of awake prone positioning (APP) on respiratory mechanics in patients with COVID-19 are not well characterized. The aim of this study was to investigate changes of global and regional lung volumes during APP compared with the supine position using electrical lung impedance tomography (EIT) in patients with hypoxemic respiratory failure due to COVID-19.

MATERIALS AND METHODS

This exploratory non-randomized cross-over study was conducted at two university hospitals in Sweden between January and May 2021. Patients admitted to the intensive care unit with confirmed COVID-19, an arterial cannula in place, a PaO2/FiO2 ratio <26.6 kPa (<200 mmHg) and high-flow nasal oxygen or non-invasive ventilation were eligible for inclusion. EIT-data were recorded at supine baseline, at 30 and 60 minutes after APP-initiation, and 30 minutes after supine repositioning. The primary outcomes were changes in global and regional tidal impedance variation (TIV), center of ventilation (CoV), global and regional delta end-expiratory lung-impedance (dEELI) and global inhomogeneity (GI) index at the end of APP compared with supine baseline. Data were reported as median (IQR).

RESULTS

All patients (n = 10) were male and age was 64 (47-73) years. There were no changes in global or regional TIV, CoV or GI-index during the intervention. dEELI increased from supine reference value 0 to 1.51 (0.32-3.62) 60 minutes after APP (median difference 1.51 (95% CI 0.19-5.16), p = 0.04) and returned to near baseline values after supine repositioning. Seven patients (70%) showed an increase >0.20 in dEELI during APP. The other EIT-variables did not change during APP compared with baseline.

CONCLUSION

Awake prone positioning was associated with a transient lung recruiting effect without changes in ventilation distribution measured with EIT in patients with hypoxemic respiratory failure due to COVID-19.

Effectiveness and safety of awake prone positioning in COVID-19-related acute hypoxaemic respiratory failure: an overview of systematic reviews

OBJECTIVE

To evaluate and summarize systematic reviews of the effects and safety of awake prone positioning for COVID-19-related acute hypoxaemic respiratory failure.

METHODS

A comprehensive search was conducted on PubMed, Embase, the Cochrane Library, Web of Science, CNKI, CSPD, CCD and CBM from their inception to March 28, 2023. Systematic reviews (SRs) of awake prone positioning (APP) for COVID-19-related acute hypoxaemic respiratory failure in adults were included. Two reviewers screened the eligible articles, and four reviewers in pairs extracted data and assessed the methodological quality/certainty of the evidence of all included SRs by AMSTAR 2 and GRADE tools. The overlap of primary studies was measured by calculating corrected covered areas. Data from the included reviews were synthesized with a narrative description.

RESULTS

A total of 11 SRs were included. The methodological quality of SRs included 1 "High", 4 "Moderate", 2 "Low" and 4 "Critically low" by AMSTAR 2. With the GRADE system, no high-quality evidence was found, and only 14 outcomes provided moderate-quality evidence. Data synthesis of the included SR outcomes showed that APP reduced the risk of requiring intubation (11 SRs) and improving oxygenation (3 SRs), whereas reduced significant mortality was not found in RCT-based SRs. No significant difference was observed in the incidence of adverse events between groups (8 SRs). The corrected covered area index was 27%, which shows very high overlap among studies.

CONCLUSION

The available SRs suggest that APP has benefits in terms of reducing intubation rates and improving oxygenation for COVID-19-related acute hypoxemic respiratory failure, without an increased risk of adverse events. The conclusion should be treated with caution because of the generally low quality of methodology and evidence.

TRIAL REGISTRATION

The protocol for this review was registered with PROSPERO: CRD42023400986. Registered 15 April 2023.

Associations of Awake Prone Positioning-Induced Changes in Physiology with Intubation: An International Prospective Observational Study in Patients with Acute Hypoxemic Respiratory Failure Related to COVID-19

INTRODUCTION

Awake prone positioning has the potential to improve oxygenation and decrease respiratory rate, potentially reducing the need for intubation in patients with acute hypoxemic respiratory failure. We investigated awake prone positioning-induced changes in oxygenation and respiratory rate, and the prognostic capacity for intubation in patients with COVID-19 pneumonia.

METHODS

International multicenter prospective observation study in critically ill adult patients with COVID-19 receiving supplemental oxygen. We collected data on oxygenation and respiratory rate at baseline, and at 1 h after being placed in prone positioning. The combined primary outcome was oxygenation and respiratory rate at 1 h. The secondary endpoint was treatment failure, defined as need for intubation within 24 h of start of awake prone positioning.

RESULTS

Between March 27th and November 2020, 101 patients were enrolled of which 99 were fully analyzable. Awake prone positioning lasted mean of 3 [2-4] h. In 77 patients (77.7%), awake prone positioning improved oxygenation, and in 37 patients (54.4%) it decreased respiratory rate. Twenty-nine patients (29.3%) were intubated within 24 h. An increase in SpO2/FiO2 of < 10 (OR 5.1, 95% CI 1.4-18.5, P = 0.01), a failure to increase PaO2/FiO2 to > 116 mmHg (OR 3.6, 95% CI 1.2-10.8, P = 0.02), and a decrease in respiratory rate of < 2 breaths/min (OR 3.6, 95% CI 1.3-9.5, P = 0.01) were independent variables associated with need for intubation. The AUC-ROC curve for intubation using a multivariable model was 0.73 (95% CI 0.62-0.84).

CONCLUSIONS

Awake prone positioning improves oxygenation in the majority of patients, and decreases respiratory rate in more than half of patients with acute hypoxemic respiratory failure caused by COVID-19. One in three patients need intubation within 24 h. Awake prone position-induced changes in oxygenation and respiratory rate have prognostic capacity for intubation within 24 h.

Effect of Awake Prone Positioning on ROX Index in Critically-ill Patients With Respiratory Failure due to COVID-19

COVID-19 pneumonia causes acute respiratory distress syndrome (ARDS). Prone positioning (PP) is beneficial to pulmonary physiology and improves oxygenation in patients with ARDS. We aimed to investigate the effect of the PP on oxygenation, respiratory rate (RR) and ROX index in non-intubated patients with COVID-19 associated respiratory failure and to determine whether ROX index predicts intubation. Awake critically-ill patients with confirmed diagnosis of COVID-19 who underwent PP were enrolled in the retrospective, single-center study. Oxygenation parameters were recorded 1 h before PP, during PP and 1 h after return to supine position (after PP). Intubation was defined as the endpoint. Seventy-one patients with a median age of 64 [55-73] years were enrolled in the study. PaO2/FiO2 and SpO2/FiO2 improved during PP, this improvement did not persist after PP. RR improved during and after PP in both intubated and non-intubated patients (for all P < .001). ROX index improved only in non-intubated patients (P < .001) but not in intubated patients (P = .07). Area under the curve (AUC) of ROX index for intubation before PP, during PP and after PP were 0.74 [0.61-0.88] (P = .002), 0.76 [0.62-0.91] (P = .001), and 0.76 [0.64-0.89] (P = .001), respectively. ROX index >6.83 before PP had a negative predictive value (NPV) of 0.85; ROX index >8.28 during PP had a NPV of 0.88 and ROX index >7.48 after PP had a NPV of 0.85. In logistic regression adjusted for APACHE II score, ROX index ≤6.83 before PP had an odds ratio (OR) 4.47 [1.39-14.38], ROX index ≤8.28 during PP had an OR 7.96 [2.29-27.64] and ROX index ≤7.48 had an OR 3.98 [1.25-12.61] for prediction of intubation. In conclusion, awake PP improves oxygenation and decreases RR. ROX index improved only in non- intubated patients and a higher ROX index predicts lower risk of progressing to mechanical ventilation with intubation.

Prone versus lateral position in acute hypoxemic respiratory failure patients with HFNO therapy: study protocol for a multicentre randomised controlled open-label trial

BACKGROUND

High-flow nasal oxygen (HFNO) therapy is a leading treatment technique for acute hypoxemic respiratory failure (AHRF), but its treatment failure rate remains high. The awake prone position (APP) has been proven to increase oxygenation and reduce the endotracheal intubation rate in patients with COVID-19-induced AHRF. However, the APP is poorly tolerated in patients, and its performance in improving prognoses is controversial. The lateral position has a similar mechanism and effect to the prone position, but it is more tolerable than the prone position. Therefore, it is worth exploring whether the lateral position is better for awake patients with AHRF.

METHODS

This is a protocol for a three-arm parallel-group multicentre randomised controlled open-label exploratory trial. A total of 583 patients from two hospitals in Chongqing, China, will be randomised to take the semi-recumbent position, lateral position, or prone position at a ratio of 1:1:1. Patients are all diagnosed with AHRF secondary to non-COVID-19 pneumonia or lung infection and receiving HFNO therapy. The primary outcome is ventilator-free days in 28 days. The secondary outcomes are the 28-day intubation rate, 28-day all-cause mortality, total position change time, the incidence of adverse events, number of hours using HFNO therapy, length of hospital and intensive care unit (ICU) stay, and others. We will conduct subgroup analyses on the arterial partial pressure of oxygen to the fraction of inspiration oxygen (PaO2/FiO2) ratio (> 200 mmHg or ≤ 200 mmHg), time from admission to intervention implementation (< 24 h or ≥ 24 h), position changing time, and different diagnoses.

DISCUSSION

This trial will explore the prognostic effects of the APP with that of the lateral position in awake patients with non-COVID-19AHRF and compare the differences between them. To provide evidence for clinical decision-making and further research on position management.

TRIAL REGISTRATION

This trial was registered in the Chinese Clinical Trial Registry. The registration number is ChiCTR2200055822 . Registered on January 20, 2022.

Prone Positioning for Patients With COVID-19-Induced Acute Hypoxemic Respiratory Failure: Flipping the Script

During the COVID-19 pandemic, prone positioning (PP) emerged as a widely used supportive therapy for patients with acute hypoxemic respiratory failure caused by COVID-19 infection. In particular, awake PP (APP)-the placement of non-intubated patients in the prone position-has gained popularity and hence is detailed first herein. This review discusses recent publications on the use of PP for non-intubated and intubated subjects with COVID-19, highlighting the physiological responses, clinical outcomes, influential factors affecting treatment success, and strategies to improve adherence with APP. The use of prolonged PP and the use of PP for patients undergoing extracorporeal membrane oxygenation are also presented.

Awake prone positioning in acute hypoxaemic respiratory failure

Awake prone positioning (APP) of patients with acute hypoxaemic respiratory failure gained considerable attention during the early phases of the coronavirus disease 2019 (COVID-19) pandemic. Prior to the pandemic, reports of APP were limited to case series in patients with influenza and in immunocompromised patients, with encouraging results in terms of tolerance and oxygenation improvement. Prone positioning of awake patients with acute hypoxaemic respiratory failure appears to result in many of the same physiological changes improving oxygenation seen in invasively ventilated patients with moderate-severe acute respiratory distress syndrome. A number of randomised controlled studies published on patients with varying severity of COVID-19 have reported apparently contrasting outcomes. However, there is consistent evidence that more hypoxaemic patients requiring advanced respiratory support, who are managed in higher care environments and who can be prone for several hours, benefit most from APP use. We review the physiological basis by which prone positioning results in changes in lung mechanics and gas exchange and summarise the latest evidence base for APP primarily in COVID-19. We examine the key factors that influence the success of APP, the optimal target populations for APP and the key unknowns that will shape future research.

Awake prone positioning for non-intubated patients with COVID-19-related acute hypoxic respiratory failure: a systematic review based on eight high-quality randomized controlled trials

BACKGROUND

Awake prone positioning has been widely used in non-intubated patients with acute hypoxic respiratory failure (AHRF) due to COVID-19, but the evidence is mostly from observational studies and low-quality randomized controlled trials (RCTs), with conflicting results from published studies. A systematic review of published high-quality RCTs to resolve the controversy over the efficacy and safety of awake prone positioning in non-intubated patients with AHRF due to COVID-19.

METHODS

Candidate studies were identified through searches of PubMed, Web of Science, Cochrane, Embase, Scopus databases from December 1, 2019 to November 1, 2022. Literature screening, data extraction and risk of bias assessment were independently conducted by two researchers.

RESULTS

Eight RCTs involving 2657 patients were included. Meta-analysis of fixed effects models showed that awake prone positioning did not increase mortality(OR = 0.88, 95%CI [0.72, 1.08]), length of stay in ICU (WMD = 1.14, 95%CI [-0.45, 2.72]), total length of stay (WMD = 0.11, 95%CI [-1.02, 1.23]), or incidence of adverse events (OR = 1.02, 95%CI [0.79, 1.31]) compared with usual care, but significantly reduced the intubation rate (OR = 0.72, 95%CI [0.60, 0.86]). Similar results were found in a subgroup analysis of patients who received only high flow nasal cannula (Mortality: OR = 0.86, 95%CI [0.70, 1.05]; Intubation rate: OR = 0.69, 95%CI [0.58, 0.83]). All eight RCTs had high quality of evidence, which ensured the reliability of the meta-analysis results.

CONCLUSIONS

Awake prone positioning is safe and feasible in non-intubated patients with AHRF caused by COVID-19, and can significantly reduce the intubation rate. More studies are needed to explore standardized implementation strategies for the awake prone positioning.

TRIAL REGISTRATION

CRD42023394113.

Prone position versus usual care in hypoxemic COVID-19 patients in medical wards: a randomised controlled trial

BACKGROUND

Benefit of early awake prone positioning for COVID-19 patients hospitalised in medical wards and who need oxygen therapy remains to be demonstrated. The question was considered at the time of COVID-19 pandemic to avoid overloading the intensive care units. We aimed to determine whether prone position plus usual care could reduce the rate of non-invasive ventilation (NIV) or intubation or death as compared to usual care alone.

METHODS

In this multicentre randomised clinical trial, 268 patients were randomly assigned to awake prone position plus usual care (N = 135) or usual care alone (N = 132). The primary outcome was the proportion of patients who underwent NIV or intubation or died within 28 days. Main secondary outcomes included the rates of NIV, of intubation or death, within 28 days.

RESULTS

Median time spent each day in the prone position within 72 h of randomisation was 90 min (IQR 30-133). The proportion of NIV or intubation or death within 28 days was 14.1% (19/135) in the prone position group and 12.9% (17/132) in the usual care group [odds ratio adjusted for stratification (aOR) 0.43; 95% confidence interval (CI) 0.14-1.35]. The probability of intubation, or intubation or death (secondary outcomes) was lower in the prone position group than in the usual care group (aOR 0.11; 95% CI 0.01-0.89 and aOR 0.09; 95% CI 0.01-0.76, respectively) in the whole study population and in the prespecified subgroup of patients with SpO2 ≥ 95% on inclusion (aOR 0.11; 95% CI 0.01-0.90, and aOR 0.09; 95% CI 0.03-0.27, respectively).

CONCLUSIONS

Awake prone position plus usual care in COVID-19 patients in medical wards did not decrease the composite outcome of need for NIV or intubation or death. Trial registration ClinicalTrials.gov Identifier: NCT04363463 . Registered 27 April 2020.

Awake prone position in COVID-19-related acute respiratory failure: a meta-analysis of randomized controlled trials

BACKGROUND

We aimed to investigate the effects of awake prone positioning (APP) in nonintubated adult patients with acute hypoxemic respiratory failure due to COVID-19.

METHODS

The PubMed, Embase, Web of Science and Cochrane Central Register databases were searched up to June 1, 2022. All randomized trials investigating the effects of APP were included in the present meta-analysis. The primary outcome was intubation rate, and the secondary outcomes included the length of intensive care unit (ICU) stay, hospital stay, and mortality. Prescribed subgroup analysis was also conducted.

RESULTS

A total of 10 randomized trials enrolling 2324 patients were ultimately included in the present study. The results indicated that APP was associated with a significant reduction in the intubation rate (OR 0.77, 95% CI 0.63 to 0.93, P = 0.007). However, no differences could be observed in the length of ICU stay or hospitalization or mortality. Subgroup analysis suggested that patients in the ICU settings (OR 0.74, 95% CI 0.60 to 0.91, P = 0.004), patients whose median APP time was more than 4 h (OR 0.77, 95% CI 0.63 to 0.93, P = 0.008), and patients with an average baseline SpO₂ to FiO₂ ratio less than 200 (OR 0.75, 95% CI 0.61 to 0.92) were more likely to benefit from APP, indicated a significantly reduced intubation rate.

CONCLUSION

Based on the current evidence, nonintubated adult patients with hypoxemic respiratory failure due to COVID-19 infection who underwent APP were shown to have a significantly reduced intubation rate. However, no differences in ICU or hospital length of stay or mortality could be observed between APP and usual care.

REGISTRATION NUMBER

CRD42022337846.

High flow nasal oxygen and awake prone positioning - Two allies against COVID-19: A systematic review

INTRODUCTION

Severe acute respiratory distress syndrome coronavirus disease-2 (SARS-CoV-2) can lead to acute hypoxemic respiratory failure (AHRF) with possible multisystemic involvement. Ventilation/perfusion mismatch and shunt increase are critical determinants of hypoxemia. Understanding hypoxemia and the mechanisms involved in its genesis is essential to determine the optimal therapeutic strategy. High flow nasal oxygen (HFNO) and awake prone positioning (APP) in patients with COVID-19 AHRF showed promising benefits. The aim of this systematic review was to depict current situation around the combined use of HFNO and APP in patients with COVID-19 AHRF. Particularly, to investigate and report the pathophysiological rationale for adopting this strategy and to evaluate the (1) criteria for initiation, (2) timing, monitoring and discontinuation, and to assess the (3) impact of HFNO/ APP on outcome.

METHODS

We performed a systematic search collecting the articles present in PubMed, Scopus, EMBASE, and Cochrane databases with the following keywords: COVID-19 pneumonia, high flow nasal oxygen, awake prone position ventilation.

RESULTS

Thirteen studies displayed inclusion criteria and were included, accounting for 1242 patients who received HFNO/ APP. The combination of HFNO/ APP has an encouraging pathophysiological rationale for implementing this technique. The recognition of patients who can benefit from HFNO/ APP is difficult and there are no validated protocols to start, monitoring, and discontinue HFNO/ APP therapy. The most used method to monitor the efficacy and failure of this combined technique are oxygenation indexes, but discontinuation techniques are inconsistently and poorly described limiting possible generatability. Finally, this technique provided no clear benefits on outcome.

CONCLUSIONS

Our systematic search provided positive feedbacks for improving the utilization of this combination technique, although we still need further investigation about methods to guide timing, management, and discontinuation, and to assess the intervention effect on outcome.

Awake prone position in COVID-19 acute respiratory failure: a randomized crossover study using electrical impedance tomography

Background

The goal of this study was to determine whether an awake prone position (aPP) reduces the global inhomogeneity (GI) index of ventilation measured by electrical impedance tomography (EIT) in COVID-19 patients with acute respiratory failure (ARF).

Methods

This prospective crossover study included COVID-19 patients with COVID-19 and ARF defined by PaO2:FiO2of 100–300 mmHg. After baseline evaluation and 30 min EIT recording in the supine position (SP), patients were randomized into one of two sequences: SP-aPP or aPP-SP. At the end of each 2 h step, oxygenation, respiratory rate, Borg scale, and 30 min EIT were recorded.

Results

Ten patients were randomized in each group. The GI index did not change in the SP-aPP group (baseline 74±20%, end of SP 78±23% and end of aPP 72±20%, p=0.85) or in the aPP-SP group (baseline 59±14%, end of aPP 59±15% and end of SP 54±13%, p=0.67). In the whole cohort, PaO2:FiO2increased from 133±44 mmHg at baseline to 183±66 mmHg in aPP (p=0.003) and decreased to 129±49 mmHg in SP (p=0.03).

Conclusion

In spontaneously breathing non-intubated COVID-19 patients with acute respiratory failure, aPP was not associated with a decrease of lung ventilation inhomogeneity assessed by EIT, despite an improvement in oxygenation.

Techniques for Oxygenation and Ventilation in Coronavirus Disease 2019

This paper discusses mechanisms of hypoxemia and interventions to oxygenate critically ill patients with COVID-19 which range from nasal cannula to noninvasive and mechanical ventilation. Noninvasive ventilation includes continuous positive airway pressure ventilation (CPAP) and high-flow nasal cannula (HFNC) with or without proning. The evidence for each of these modalities is discussed and thereafter, when to transition to mechanical ventilation (MV). Various techniques of MV, again with and without proning, and rescue strategies which would include extra corporeal membrane oxygenation (ECMO) when it is available and permissive hypoxemia where it is not, are discussed.

Prone Positioning for Acute Hypoxemic Respiratory Failure and ARDS: A Review

Prone positioning is an immediately accessible, readily implementable intervention that was proposed initially as a method for improvement in gas exchange > 50 years ago. Initially implemented clinically as an empiric therapy for refractory hypoxemia, multiple clinical trials were performed on the use of prone positioning in various respiratory conditions, cumulating in the landmark Proning Severe ARDS Patients trial, which demonstrated mortality benefit in patients with severe ARDS. After this trial and the corresponding meta-analysis, expert consensus and societal guidelines recommended the use of prone positioning for the management of severe ARDS. The ongoing COVID-19 pandemic has brought prone positioning to the forefront of medicine, including widespread implementation of prone positioning in awake, spontaneously breathing, nonintubated patients with acute hypoxemic respiratory failure. Multiple clinical trials now have been performed to investigate the safety and effectiveness of prone positioning in these patients and have enhanced our understanding of the effects of the prone position in respiratory failure. In this review, we discuss the physiologic features, clinical outcome data, practical considerations, and lingering questions of prone positioning.

Awake Prone Positioning for Non-Intubated COVID-19 Patients with Acute Respiratory Failure: A Meta-Analysis of Randomised Controlled Trials

INTRODUCTION

Awake prone positioning (APP) has been widely applied in non-intubated patients with COVID-19-related acute hypoxemic respiratory failure. However, the results from randomised controlled trials (RCTs) are inconsistent. We performed a meta-analysis to assess the efficacy and safety of APP and to identify the subpopulations that may benefit the most from it.

METHODS

We searched five electronic databases from inception to August 2022 (PROSPERO registration: CRD42022342426). We included only RCTs comparing APP with supine positioning or standard of care with no prone positioning. Our primary outcomes were the risk of intubation and all-cause mortality. Secondary outcomes included the need for escalating respiratory support, length of ICU and hospital stay, ventilation-free days, and adverse events.

RESULTS

We included 11 RCTs and showed that APP reduced the risk of requiring intubation in the overall population (RR 0.84, 95% CI: 0.74-0.95; moderate certainty). Following the subgroup analyses, a greater benefit was observed in two patient cohorts: those receiving a higher level of respiratory support (compared with those receiving conventional oxygen therapy) and those in intensive care unit (ICU) settings (compared to patients in non-ICU settings). APP did not decrease the risk of mortality (RR 0.93, 95% CI: 0.77-1.11; moderate certainty) and did not increase the risk of adverse events.

CONCLUSIONS

In patients with COVID-19-related acute hypoxemic respiratory failure, APP likely reduced the risk of requiring intubation, but failed to demonstrate a reduction in overall mortality risk. The benefits of APP are most noticeable in those requiring a higher level of respiratory support in an ICU environment.

Prone position: how understanding and clinical application of a technique progress with time

Historical background

The prone position was first proposed on theoretical background in 1974 (more advantageous distribution of mechanical ventilation). The first clinical report on 5 ARDS patients in 1976 showed remarkable improvement of oxygenation after pronation. 

Pathophysiology

The findings in CT scans enhanced the use of prone position in ARDS patients. The main mechanism of the improved gas exchange seen in the prone position is nowadays attributed to a dorsal ventilatory recruitment, with a substantially unchanged distribution of perfusion. Regardless of the gas exchange, the primary effect of the prone position is a more homogenous distribution of ventilation, stress and strain, with similar size of pulmonary units in dorsal and ventral regions. In contrast, in the supine position the ventral regions are more expanded compared with the dorsal regions, which leads to greater ventral stress and strain, induced by mechanical ventilation.

Outcome in ARDS

The number of clinical studies paralleled the evolution of the pathophysiological understanding. The first two clinical trials in 2001 and 2004 were based on the hypothesis that better oxygenation would lead to a better survival and the studies were more focused on gas exchange than on lung mechanics. The equations better oxygenation = better survival was disproved by these and other larger trials (ARMA trial). However, the first studies provided signals that some survival advantages were possible in a more severe ARDS, where both oxygenation and lung mechanics were impaired. The PROSEVA trial finally showed the benefits of prone position on mortality supporting the thesis that the clinical advantages of prone position, instead of improved gas exchange, were mainly due to a less harmful mechanical ventilation and better distribution of stress and strain. In less severe ARDS, in spite of a better gas exchange, reduced mechanical stress and strain, and improved oxygenation, prone position was ineffective on outcome.

Prone position and COVID-19

The mechanisms of oxygenation impairment in early COVID-19 are different than in typical ARDS and relate more on perfusion alteration than on alveolar consolidation/collapse, which are minimal in the early phase. Bronchial shunt may also contribute to the early COVID-19 hypoxemia. Therefore, in this phase, the oxygenation improvement in prone position is due to a better matching of local ventilation and perfusion, primarily caused by the perfusion component. Unfortunately, the conditions for improved outcomes, i.e. a better distribution of stress and strain, are almost absent in this phase of COVID-19 disease, as the lung parenchyma is nearly fully inflated. Due to some contradictory results, further studies are needed to better investigate the effect of prone position on outcome in COVID-19 patients.

Graphical Abstract

Effects of awake prone position vs. usual care on acute hypoxemic respiratory failure in patients with COVID-19: A systematic review and meta-analysis of randomized controlled trials

Background

Previous studies have shown that an awake prone position may be beneficial for the treatment of acute respiratory distress syndrome (ARDS) or acute hypoxic respiratory failure (AHRF) in patients with COVID-19, but the results are not consistent, especially in terms of oxygenation outcomes and intubation rate. This systematic review and meta-analysis assessed the effects of the awake prone position on AHRF in patients with COVID-19 with all randomized controlled trials (RCTs).

Methods

An extensive search of online databases, including MEDLINE, Embase, Web of Science, and Cochrane Central Register of Controlled Trials from 1 December 2019 to 30 October 2022, with no language restrictions was performed. This systematic review and meta-analysis are based on the PRISMA statement. We only included RCTs and used the Cochrane risk assessment tool for quality assessment.

Results

Fourteen RCTs fulfilled the selection criteria, and 3,290 patients were included. A meta-analysis found that patients in the awake prone position group had more significant improvement in the SpO₂/FiO₂ ratio [mean difference (MD): 29.76; 95% confidence interval (CI): 1.39-48.13; P = 0.001] compared with the usual care. The prone position also reduced the need for intubation [odd ratio (OR): 0.72; 95% CI: 0.61 to 0.84; P < 0.0001; I ² = 0%]. There was no significant difference in mortality, hospital length of stay, incidence of intensive care unit (ICU) admission, and adverse events between the two groups.

Conclusion

The awake prone position was a promising intervention method, which is beneficial to improve the oxygenation of patients with ARDS or AHRF caused by COVID-19 and reduce the need for intubation. However, the awake prone position showed no obvious advantage in mortality, hospital length of stay, incidence of ICU admission, and adverse events.

Systematic review registration

International Prospective Register of Systematic Reviews (PROSPERO), identifier: CRD42022367885.

Efficacy and safety of prone position in COVID-19 patients with respiratory failure: a systematic review and meta-analysis

BACKGROUND

Prone position has already been demonstrated to improve survival in non-COVID acute respiratory distress syndrome and has been widely performed in COVID-19 patients with respiratory failure, both in non-intubated and intubated patients. However, the beneficial effect of the prone position in COVID-19 pneumonia still remains controversial. Therefore, we aimed to evaluate the effectiveness and safety of the prone position compared with the non-prone in non-intubated and intubated COVID-19 patients, respectively.

METHODS

We searched the MEDLINE, EMBASE, and Cochrane databases, as well as one Korean domestic database, on July 9, 2021, and updated the search 9 times to September 14, 2022. Studies that compared prone and non-prone positions in patients with COVID-19 were eligible for inclusion. The primary outcomes were mortality, need for intubation, and adverse events.

RESULTS

Of the 1259 records identified, 9 randomized controlled trials (RCTs) and 23 nonrandomized studies (NRSs) were eligible. In the non-intubated patients, the prone position reduced the intubation rate compared with the non-prone position in 6 RCTs (n = 2156, RR 0.81, P = 0.0002) and in 18 NRSs (n = 3374, RR 0.65, P = 0.002). In the subgroup analysis according to the oxygen delivery method, the results were constant only in the HFNC or NIV subgroup. For mortality, RCTs reported no difference between prone and non-prone groups, but in NRSs, the prone position had a significant advantage in mortality [18 NRSs, n = 3361, relative risk (RR) 0.56, P < 0.00001] regardless of the oxygen delivery methods shown in the subgroup analysis. There was no RCT for intubated patients, and mortality did not differ between the prone and non-prone groups in NRSs. Adverse events reported in both the non-intubated and intubated groups were mild and similar between the prone and non-intubated groups.

CONCLUSION

For non-intubated patients with COVID-19, prone positioning reduced the risk of intubation, particularly in patients requiring a high-flow oxygen system. However, the survival benefit was unclear between the prone and non-prone groups. There was insufficient evidence to support the beneficial effects of prone positioning in intubated patients. Trial registration This study was registered in the Prospective Register of Systematic Reviews on February 16, 2022 (Registration No.: CRD42022311150 ).

Lung ultrasound response to awake prone positioning predicts the need for intubation in patients with COVID-19 induced acute hypoxemic respiratory failure: an observational study

Background

Awake prone positioning (APP) reduces the intubation rate in COVID-19 patients treated by high-flow nasal cannula (HFNC). However, the lung aeration response to APP has not been addressed. We aimed to explore the lung aeration response to APP by lung ultrasound (LUS).

Methods

This two-center, prospective, observational study enrolled patients with COVID-19-induced acute hypoxemic respiratory failure treated by HFNC and APP. LUS score was recorded 5–10 min before, 1 h after APP, and 5–10 min after supine in the first APP session within the first three days. The primary outcome was LUS score changes in the first three days. Secondary outcomes included changes in SpO₂/FiO₂ ratio, respiratory rate and ROX index (SpO₂/FiO₂/respiratory rate) related to APP, and the rate of treatment success (patients who avoided intubation).

Results

Seventy-one patients were enrolled. LUS score decreased from 20 (interquartile range [IQR] 19–24) to 19 (18–21) (p < 0.001) after the first APP session, and to 19 (18–21) (p < 0.001) after three days. Compared to patients with treatment failure (n = 20, 28%), LUS score reduction after the first three days in patients with treatment success (n = 51) was greater (− 2.6 [95% confidence intervals − 3.1 to − 2.0] vs 0 [− 1.2 to 1.2], p = 0.001). A decrease in dorsal LUS score > 1 after the first APP session was associated with decreased risk for intubation (Relative risk 0.25 [0.09–0.69]). APP daily duration was correlated with LUS score reduction in patients with treatment success, especially in dorsal lung zones (r =  − 0.76; p < 0.001).

Conclusions

In patients with acute hypoxemic respiratory failure due to COVID-19 and treated by HFNC, APP reduced LUS score. The reduction in dorsal LUS scores after APP was associated with treatment success. The longer duration on APP was correlated with greater lung aeration.

Trial registration This study was prospectively registered on clinicaltrials.gov on April 22, 2021. Identification number NCT04855162.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13054-022-04064-3.

Reply to: Effect of prone positioning without mechanical ventilation in COVID-19 patients with acute respiratory failure

We have read the letter by Yanfei Shen and co-workers, and appreciate their interest in our study of awake prone positioning (APP) in non-intubated patients with acute hypoxaemic respiratory failure (AHRF) due to coronavirus disease 2019 (COVID-19). We would like to add a few comments to their purposeful remarks.

Several questions on the efficacy of awake prone positioning for hypoxaemic respiratory failure remain unanswered. Research targeting those questions is needed. https://bit.ly/3xmbNPP

Application of High-Flow Nasal Cannula in COVID-19: A Narrative Review

Background: During the first wave of COVID-19, the large influx of severely ill patients led to insufficient availability of beds in intensive care units and a shortage of ventilators. The shortage of ventilators, high mortality of intubated patients, and high risk of infections among healthcare workers involved in intubation were the main factors that led to the prevalence of noninvasive respiratory support during the pandemic. The high-flow nasal cannula (HFNC) is a commonly used, popular form of noninvasive respiratory support. Due to its unique physiological effects, HFNC can provide a high fraction of humidified oxygen and is satisfactorily comfortable for patients with COVID-19. However, before the COVID-19 era, there was little evidence on the application of HFNC in patients with acute respiratory failure caused by viral infection. Aim: This narrative review provides an overview of recent studies on the use of HFNC in patients with COVID-19-related acute hypoxemic respiratory failure. The main topics discussed include the probability of successful use of HFNC in these patients, whether late intubation increases mortality, the availability of convenient and accurate monitoring tools, comparison of HFNC with other types of noninvasive respiratory support, whether HFNC combined with the prone position is more clinically useful, and strategies to further reduce the infection risk associated with HFNC. The implication of this study is to identify some of the limitations and research gaps of the current literature and to give some advice for future research.

Awake prone positioning for patients with COVID-19-induced acute hypoxemic respiratory failure

Whereas prone positioning of intubated patients suffering from acute respiratory distress syndrome represents the standard of care, proning non-intubated patients, so-called "awake prone positioning (APP)," has only recently gained popularity and undergone scientific evaluation. In this review, we summarize current evidence on physiological and clinical effects of APP on patients' centered outcomes, such as intubation and mortality, the safety of the technique, factors and predictors of success, practical issues for optimal implementation, and future areas of research. Current evidence supports using APP among patients suffering from acute hypoxemic respiratory failure due to COVID-19 and undergoing advanced respiratory support, such as high-flow nasal cannula, in an intensive care unit setting. Healthcare teams should aim to prone patients at least 8 h daily. Future research should focus on optimizing the tolerance of the technique and comprehensively evaluating benefits in other patient populations.

Awake prone positioning for patients with COVID-19 pneumonia in intensive care unit: A systematic review and meta-analysis

Background

Awake prone positioning (APP) has been widely used in non-intubated COVID-19 patients during the pandemic. However, high-quality evidence to support its use in severe COVID-19 patients in an intensive care unit (ICU) is inadequate. Therefore, we aimed to assess the efficacy and safety of APP for intubation requirements and other important outcomes in this patient population.

Methods

We searched for potentially relevant articles in PubMed, Embase, and the Cochrane database from inception to May 25, 2022. Studies focusing on COVID-19 adults in ICU who received APP compared to controls were included. The primary outcome was the intubation requirement. Secondary outcomes were mortality, ICU stay, and adverse events. Study quality was independently assessed, and we also conducted subgroup analysis, sensitivity analysis, and publication bias to explore the potential influence factors.

Results

Ten randomized controlled trials with 1,686 patients were eligible. The quality of the included studies was low to moderate. Overall, the intubation rate was 35.2% in the included patients. The mean daily APP duration ranged from &lt;6 to 9 h, with poor adherence to APP protocols. When pooling, APP significantly reduced intubation requirement (risk ratio [RR] 0.84; 95%CI, 0.74–0.95; I2 = 0%, P = 0.007). Subgroup analyses confirmed the reduced intubation rates in patients who were older (≥60 years), obese, came from a high mortality risk population (&gt;20%), received HFNC/NIV, had lower SpO2/FiO2 (&lt;150 mmHg), or undergone longer duration of APP (≥8 h). However, APP showed no beneficial effect on mortality (RR 0.92 [95% CI 0.77–1.10; I2 = 0%, P = 0.37] and length of ICU stay (mean difference = −0.58 days; 95% CI, −2.49 to 1.32; I2 = 63%; P = 0.55).

Conclusion

APP significantly reduced intubation requirements in ICU patients with COVID-19 pneumonia without affecting the outcomes of mortality and ICU stay. Further studies with better APP protocol adherence will be needed to define the subgroup of patients most likely to benefit from this strategy.

Effect of Awake Prone Positioning in non-Intubated COVID-19 Patients with Acute Hypoxemic Respiratory Failure: A Systematic Review and Meta-Analysis

Background

Awake prone positioning (APP) has been considered as a feasible treatment for patients with acute hypoxemic respiratory failure in non-intubated coronavirus disease 2019 (COVID-19). However, the efficacy and safety of APP remain uncertain. This meta-analysis aims to assess the effect of APP on intubation rate and mortality in COVID-19 patients with acute respiratory failure.

Methods

Relevant studies published from January 1, 2020, to June 17, 2022, were systematically searched. The primary outcomes were the intubation rate and mortality; the secondary outcome was the incidence of adverse events.

Results

Of 5746 identified publications, 22 were eligible for inclusion in the meta-analysis (N = 5146 patients). In comparison to the non-APP group, APP could decrease the intubation rates (OR 0.64; 95% CI 0.48-0.83; P = .001), particularly in the subgroup of the daily median duration of APP > 8 h and in the subgroup of receiving high flow nasal cannula (HFNC) or non-invasive ventilation (NIV). Patients treated with APP were associated with lower mortality rates (OR 0.61; 95% CI 0.45-0.81; P = .0008), but no mortality benefit was found in the APP group in the subgroup of randomized controlled trials (RCTs). No significant difference was found in the incidence of adverse events between the groups (OR 1.13; 95% CI 0.75-1.71; P = .56).

Conclusion

Our results demonstrated that APP could be an effective strategy to avoid intubation without detrimental effects in non-intubated patients with COVID-19, especially for patients requiring HFNC or NIV, and the daily APP duration with the target of minimally eight hours was suggested. In the subgroup of RCTs, the pooled results did not demonstrate any benefit of APP on mortality. Given the limited number of RCTs, further high-quality RCTs are needed to confirm the results.

INPLASY registration number

INPLASY2021110037.