Feasibility and physiological effects of prone positioning in non-intubated patients with acute respiratory failure due to COVID-19 (PRON-COVID): a prospective cohort study

Awake prone positioning in a patient with respiratory impairment due to subarachnoid hemorrhage: a case report

BACKGROUND

Prone positioning has been shown to be an effective rescue strategy in severe acute respiratory distress syndrome and was widely used during the coronavirus disease 2019 pandemic, both in mechanically ventilated and in awake patients. Subarachnoid hemorrhage is often associated with respiratory failure. Prone positioning has been used in brain-injured patients, but concerns relating to neurological complications from intracranial hypertension still remain.

CASE PRESENTATION

We report the case of a 59-year-old Italian patient with subarachnoid hemorrhage who safely underwent awake prone positioning after deterioration of respiratory function.

CONCLUSIONS

In this report, we show that awake pronation is possible in patients with subarachnoid hemorrhage. However, careful monitoring of Intracranial pressure and clinical examination may be the keys to successful application of this procedure.

The effects of prolonged prone positioning on response and prognosis in patients with acute respiratory distress syndrome: a retrospective cohort study

BACKGROUND

Prone positioning improves outcomes in patients with acute respiratory distress syndrome (ARDS), but the optimal duration in critical care settings remains uncertain. This study aims to evaluate the investigates the impact of prone ventilation duration on clinical outcomes.

METHODS

This retrospective study was conducted on ARDS patients admitted to the intensive care unit (ICU), Nanfang hospital of Southern Medical University, who received prone positioning. Patients were categorized into two groups: the prolonged prone positioning (PPP) (≥ 16 h) group and the standard prone positioning (SPP) (< 16 h) group. Propensity score matching (PSM) was employed to balance baseline characteristics. Cox proportional hazards, regression models were utilized to evaluate the association between the prone duration and clinical outcomes. Kaplan-Meier survival curves were generated to compare 28-day mortality, with log-rank tests analyzing differences. Restricted cubic spline (RCS) were applied to investigate the time-response between prone duration, PaCO₂, PaO₂, positive end-expiratory pressure, response rate, and 28-day mortality. In addition, the incidence of prone position-related complications was assessed in both groups.

RESULTS

A total of 234 patients with ARDS were included, with an overall 28-day mortality of 49.1% (115/234). After PSM, 81 matched pairs were compared. The PPP group had lower 28-day mortality (46.9% vs. 53.1%; hazard ratios (HR): 0.53; 95% CI 0.32-0.85; P = 0.033) and improved prone positioning response rate [70.5% vs. 60.5%; odds ratio (OR): 1.46; 95% CI 1.23-1.89; P = 0.025]. RCS analysis suggested a reduction in mortality with prone durations ≥ 16 h, and longer durations correlated with better prone response. However, no significant association was found between PPP and reduced ICU or hospital length of stay. RCS analysis indicated a gradual decrease in 28-day mortality with increasing duration of prone positioning, and longer duration were associated with a higher likelihood of a prone response. There were no significant differences in prone ventilation-related complications between the two groups.

CONCLUSIONS

PPP (≥ 16 h) is associated with reduced 28-day mortality and improved response rates in ICU patients with ARDS, without increasing complication risks. Prospective studies are needed to further validate these results.

Advances in acute respiratory distress syndrome: focusing on heterogeneity, pathophysiology, and therapeutic strategies

In recent years, the incidence of acute respiratory distress syndrome (ARDS) has been gradually increasing. Despite advances in supportive care, ARDS remains a significant cause of morbidity and mortality in critically ill patients. ARDS is characterized by acute hypoxaemic respiratory failure with diffuse pulmonary inflammation and bilateral edema due to excessive alveolocapillary permeability in patients with non-cardiogenic pulmonary diseases. Over the past seven decades, our understanding of the pathology and clinical characteristics of ARDS has evolved significantly, yet it remains an area of active research and discovery. ARDS is highly heterogeneous, including diverse pathological causes, clinical presentations, and treatment responses, presenting a significant challenge for clinicians and researchers. In this review, we comprehensively discuss the latest advancements in ARDS research, focusing on its heterogeneity, pathophysiological mechanisms, and emerging therapeutic approaches, such as cellular therapy, immunotherapy, and targeted therapy. Moreover, we also examine the pathological characteristics of COVID-19-related ARDS and discuss the corresponding therapeutic approaches. In the face of challenges posed by ARDS heterogeneity, recent advancements offer hope for improved patient outcomes. Further research is essential to translate these findings into effective clinical interventions and personalized treatment approaches for ARDS, ultimately leading to better outcomes for patients suffering from ARDS.

Dose-response relationship between awake prone-positioning duration and PaO2/FiO2 changes and risk of disease aggravation in patients with severe COVID-19: A prospective cohort study

BACKGROUND

Patients not mechanically ventilated often fail to achieve the recommended duration of awake prone positioning due to treatment interruption and discomfort. Few studies have investigated the link between treatment outcome and prone-positioning duration, the inability to accurately guide patients to perform awake prone positioning.

OBJECTIVES

The aim of this study was to characterise and explore the relationship between awake prone-positioning duration with the ratio of the partial pressure of arterial oxygen to the fraction of inspired oxygen (PaO2/FiO2 [P/F]) changes and the risk of disease aggravation.

METHODS

A prospective cohort study; dose-response relationship was used. Awake prone positioning was performed on patients with severe Corona Virus Disease 2019 (COVID-19) for 5 consecutive days from 1 February to 21 March 2023. Linear and logistic regression models were utilised to assess the association between prone-positioning duration with P/F changes and risk of disease aggravation, respectively. Meanwhile, the restricted cubic spline was used to evaluate the dose-response relationships.

RESULTS

A total of 408 patients with severe COVID-19 were analysed. The daily prone positioning duration was 4.57 ± 2.74 h/d, and the changes in P/F were 67.63 ± 69.17 mmHg. On the sixth day of hospitalisation, the condition of 52 (12.8%) patients deteriorated. There was a positive, nonlinear dose-response relationship (Poverall < 0.001, Pnonlinearity = 0.041) and a strong, significant positive correlation (β = 29.286, t = 4.302, P < 0.001) between the prone-positioning duration and P/F changes. The risk of disease aggravation gradually decreases with the increase of prone-positioning duration. Nonetheless, the prone-positioning duration was not statistically associated with disease aggravation (odds ratio = 0.986, 95% confidence interval: 0.514-1.895).

CONCLUSIONS

Awake prone positioning for ≥4 h/d is effective on oxygenation (not mortality/intubation) and is achievable for patients with severe COVID-19. Prolonged prone positioning is promising in improving patients' oxygenation but does not alleviate their risk of disease aggravation.

The effect of prone positioning on ventilator parameters, blood gas levels, and ventilator-associated pneumonia in intensive care unit patients: a randomized controlled trial

OBJECTIVES

This study was planned to compare the prone position and non-prone position groups and to evaluate arterial blood gas results, mechanical ventilator values and ventilator-associated pneumonia (VAP) status before, during, and after patients were brought back to the non-prone position.

DESIGN

This study is a randomized controlled trial with a parallel-group design and a 1:1 allocation ratio. A block randomisation method was used to ensure balanced allocation between two groups.

SETTING

The research was conducted in the 14-bed and 26-bed general ICUs of two private hospitals on the European side of Istanbul.

PARTICIPANTS

The 94 eligible participants were randomly divided into two groups. 52 participants were assigned to the prone position group, while 42 participants were assigned to the non-prone position group, which served as the control group. In the end, 40 participants were in each group.

INTERVENTION

The intervention involved placing patients in the prone position and monitoring their arterial blood gas results, mechanical ventilator values, and VAP status at multiple stages: before, during, and after returning them to the non-prone position. Each patient was followed for a minimum of 5 days.

RESULTS

The majority of the participants were male (51.2%) and aged 45-64 (48.8%). The comparison of experimental and control groups indicated statistically significant difference in saturation, FiO₂, inspiratory-expiratory tidal volume, and blood gas levels of the patients in the treatment group (p = 0.001; p < 0.01).

CONCLUSIONS

The change in the experimental group was greater than in the control group. In conclusion, the mechanical ventilator parameters and blood gas levels of the patients in the treatment group were better than those of the patients in the control group. It is recommended as an effective practice in patients receiving prone position mechanical ventilation (MV).

CLINICAL TRIAL REGISTRATION NUMBER AND REGISTRATION DATE

NCT05760716/ March 6, 2023 (This trial was registered retrospectively at ClinicalTrials.gov (Registration Number: NCT05760716) after its completion due to demanded revisions. The integrity of the data and adherence to the study protocol were ensured throughout. The trial adhered to ethical standards (ethics committee approval, informed consent) even if it was not registered prospectively).

A prediction model for nonresponsive outcomes in critically ill patients with acute respiratory distress syndrome undergoing prone position ventilation: A retrospective cohort study

OBJECTIVE

This study aimed to develop a reliable and effective nomogram model to identify high-risk populations with non-response to prone position ventilation (PPV) in acute respiratory distress syndrome (ARDS) patients.

METHODS

This retrospective cohort study included 175 patients with ARDS undergoing PPV. An improvement of ≥ 20 mmHg in the PaO2/FiO2 after the first PPV was defined as a 'response'. For the construction of the model, all patients were randomly assigned to the train and validation cohort according to 2:1. Multivariate logistic regression was useed to develop the nomogram. The area under the receiver operating characteristic curve (AUC), decision curve and calibration curve were assessed to evaluate the efficiency, clinical utility and calibration of the model.

RESULTS

The overall rate of non-response to PPV in ARDS patients was approximately 32.6 %. In the training cohort and validation cohort, the rate are 29.9 % and 34.5 % respectively. Murray score ≥ 2.5 (OR: 4.29), procalcitonin (PCT) ≥ 2 ng/mL (OR: 2.52), N-terminal pro-B-type natriuretic peptide (Nt-proBNP) ≥ 2000 pg/ml (OR: 2.44), and hemoglobin ≤ 90 g/L (OR: 2.39) were independently associated with the rate of non-response to PPV and combined in prediction model. The model demonstrated good predictive value with AUC of 0.817 and 0.828 in the train and validation cohort. Calibration curve showed good calibration and decision curve analysis indicated favorable clinical utility.

CONCLUSIONS

This study constructed a risk prediction model for non-response to PPV, which demonstrated good predictive value and clinical utility.

IMPLICATIONS FOR CLINICAL PRACTICE

Early identification of prone position response in ARDS is essential for timely alternative treatments, improving patient prognosis and healthcare efficiency. The predictive model included representative indicators of patients with ARDS, encompassing parameters such as the acute lung injury (Murray score), cardiac function (Nt-proBNP), infectious status (PCT), and hemoglobin levels.

Assessing the Impact of the Prone Position on Acute Kidney Injury

Background: Prone positioning is a standard intervention in managing patients with severe acute respiratory distress syndrome (ARDS) and is known to improve oxygenation. However, its effects on other organs, particularly the kidneys, are less well understood. This study aimed to assess the association between prone positioning and the development of acute kidney injury (AKI), specifically in overweight and obese patients. Methods: A retrospective pre-post study was conducted on a cohort of 60 critically ill ARDS patients who were placed in the prone position during hospitalization. The development of AKI was assessed using the Acute Kidney Injury Network (AKIN) criteria, with AKI measured by both creatinine levels (AKINCr) and urine output (AKINUO). Patients were divided into two groups based on body mass index (BMI): overweight/obese (BMI ≥ 25) and non-obese (BMI < 25). Data were collected before and after prone positioning. Results: In overweight/obese patients (n = 39, 57 cases), both the median AKINCr and AKINUO scores increased significantly following prone positioning (from 0 to 1, median p < 0.01, and from 0 to 2, median p < 0.01, respectively). No statistically significant changes in AKIN scores were observed in non-obese patients nor were significant differences found in either group after repositioning to supine. Conclusions: Prone positioning is associated with an increased risk of acute kidney injury in overweight and obese ARDS patients. This may be due to the kidneys' susceptibility to intra-abdominal hypertension in these patients. Further research is needed to explore optimal proning strategies for overweight and obese populations.

Effect of Self-Proning on Respiratory Functions, Pneumonia Severity, and Mortality Risk Among Patients Diagnosed With Community-Acquired Pneumonia: A Nursing-Based Quasi-Experimental Study

Assessing and monitoring respiratory parameters, such as respiratory rate, oxygen saturation, and lung sounds, is crucial for the management and prognosis of pneumonia patients. Prone positioning has been shown to improve oxygenation in patients with respiratory disorders, including pneumonia, by reducing ventilation/perfusion mismatch. However, there is a lack of evidence supporting the benefits of self-proning in spontaneously breathing pneumonia patients. This study aims to evaluate the effect of self-proning on respiratory functions, pneumonia, and mortality risk among patients diagnosed with community-acquired pneumonia. The study used a pre- and post-test quasi-experimental design with a control group, adhering to the Transparent Reporting of Evaluations with Nonrandomized Designs guidelines. It was conducted in the Medical Respiratory Department inpatient wards at the Respiratory Diseases Hospital in Alexandria, Egypt. The study recruited 128 patients with community-acquired pneumonia, conveniently assigned to an intervention group (n = 64) and a control group (n = 64). Data were collected using socio-demographic and historical data sheets, respiratory parameters assessment sheets, the confusion uremia respiratory rate and blood pressure (CURB-65) severity of pneumonia score, and the Pneumonia Severity Index. Prone positioning significantly positively impacted respiratory parameters in the intervention group compared to the control group. Specifically, the intervention group exhibited improvements in respiratory rate, oxygen saturation, reduced need for supplemental oxygen, and cough (p < .05). Furthermore, the intervention group exhibited fewer changes in findings from chest inspection, palpation, and auscultation. In addition, the severity of pneumonia was reduced in the intervention group compared to the control group, as indicated by lower CURB-65 (p = .014) and pneumonia severity index scores (p = .005). The study demonstrated that self-proning interventions significantly improved respiratory functions and reduced the risk of death among participants with community-acquired pneumonia. These findings suggest that self-proning is a beneficial technique for managing respiratory distress, particularly in non-intubated patients, and can be an effective strategy to improve patient outcomes in clinical settings.

Effects of innovative modular prone positioning tools in patients with acute respiratory distress syndrome due to COVID-19 during awake prone position: a prospective randomized controlled trial

OBJECTIVES

Our aim is to investigate the effects of a innovative modular prone positioning tools on patients with acute respiratory distress syndrome (ARDS) caused by COVID-19 during awake prone positioning (AW-PP).

METHODS

This prospective randomized controlled study initially enrolled 168 patients with COVID-19 due to ARDS. However, 92 were subsequently disqualified, leaving 76 patients who were randomly assigned to either the observation group (n = 38) or the control group (n = 38). The observation group utilized innovative modular prone positioning tools for non-invasive respiratory support (NIRS), while the control group used soft pillows for the same treatment. Data were collected on comfort levels, adverse events, and efficacy indicators. Additionally, the comfort, incidence of adverse events, and treatment efficacy in both groups were evaluated.

RESULTS

The observation group had shorter the daily duration spent on executing the AW-PP (2.74 ± 0.86 min vs. 4.64 ± 1.02 min, P < 0.001), longer the daily total AW-PP (8.52 ± 1.01 h vs. 6.03 ± 0.66 h, P < 0.001), longer the daily duration until the first position adjustment (59.89 ± 12.73 min vs. 36.57 ± 8.69 min, P < 0.001), and lower the daily frequency of position adjustments during the AW-PP (11.03 ± 2.67 vs. 17.95 ± 2.58, P < 0.001) in comparison with the control group. No significant differences were observed in intubation rates, mortality, the daily number of hours under HFNO and NIV, escalated to NIV from HFNO, and hospital length of stay between the groups (P > 0.05). However, the observation group experienced significantly fewer adverse events, including kinking NIRS circuit, pain, shortness of breath, dizziness, and pressure ulcers (P < 0.05).

CONCLUSION

Innovative modular prone positioning tools improved efficiency, comfort, and reduced adverse events during AW-PP but did not affect intubation rates or mortality.

Physiologic effects of prone positioning on gas exchange and ventilation-perfusion matching in awake patients with AHRF

BACKGROUND

Prone positioning (PP) improves oxygenation in awake patients with acute hypoxemic respiratory failure (AHRF). However, the underlying mechanisms remain unclear in patients with diverse lung morphology. We aimed to determine the short-term effects of awake prone positioning (APP) in AHRF patients with focal and non-focal lung morphology.

METHODS

This is a prospective physiological study. Twenty-four non-intubated patients with PaO2/FiO2 ≤ 300 mm Hg were included. Gas exchange, ventilation and perfusion distribution, and hemodynamics variables were recorded in the supine position (SP1), 2 h after PP, and 1 h after re-supine (SP2). Lung morphology was classified as focal and non-focal patterns using computed tomography.

RESULTS

Twelve of the included patients were classified to the focal group and 12 to the non-focal group. PaO2/FiO2 improved after PP in all patients (161 [137, 227] mmHg vs. 236 [202, 275] mmHg, p < 0.001). Ventilation-perfusion (V/Q) matching increased after PP in all patients (61.9 [53.9, 66.5] vs. 77.5 [68.3, 80.0], p < 0.001). Shunt exhibited a significant decrease in patients of the non-focal group (28.6 [22.5, 30.3] vs. 11.3 [9.0, 14.5], p < 0.001), whereas no difference was found in the focal group after PP. Dead space decreased significantly in patients of the focal group (25.6 [21.5, 28.4] vs. 12.0 [10.8, 14.1], p < 0.001), whereas no difference was found in the non-focal group after PP.

CONCLUSIONS

APP improves V/Q matching, and large-scale, bias-free studies are needed to find more definitive differences between patients with focal and non-focal lung morphyology.

TRIAL REGISTRATION

The study is registered in ClinicalTrials.gov (trial No. NCT04754113, date of registration: 2021-02-15).

The effect of hand and body position on chest compression quality and rescuer fatigue in prone cardiopulmonary resuscitation

Aim

This study aimed to compare the quality of compressions in supine cardiopulmonary resuscitation (CPR) and prone CPR by performing chest compressions on a manikin. Evaluating the effect of prone CPR using different hand and body position on the quality of manual chest compressions and fatigue of participants.

Methods

After completing 2 min of chest compression in the supine position (Supine Group), 25 participants randomly performed three sets of 2-minutes chest compressions on a prone position manikin. Stand + hands overlapped Group: participants stood beside the patient bed with their hands overlapped and placed on the posterior segment of the thoracic spine between the scapulae, Straddle + hands separated Group: participants straddled the patient bed with their hands placed above the scapulae on both sides at the mid-chest level, and Straddle + hands overlapped Group: participants straddled the patient bed with their hands overlapping on the posterior segment of the thoracic spine between the scapulae. Subsequently, the quality of chest compressions and participants fatigue were assessed.

Results

Chest compression depth ratio and mean chest compression depth (MCCD) were worse in the three prone CPR groups (Stand + hands overlapped Group: 0.0(0.0,15.6) %, 39.8 ± 1.3 mm; Straddle + hands separated Group: 1.4(0.0,11.7) %, 42.4 ± 1.2 mm; Straddle + hands overlapped Group: 0.0(0.0,9.2) %, 40.9 ± 1.2 mm) than in the Supine group (87.1(68.1,94.0) %; p < 0.001, 52.4 ± 0.4 mm; p < 0.001). In the three prone CPR groups, Straddle + hands separated Group had the greatest MCCD, lowest changes in heart rate (p = 0.018) and lowest changes in RPE scores (p < 0.001). There were no significant differences between the four groups in terms of mean chest compression rate, accurate chest compression rate ratio, or correct recoil ratio.

Conclusion

This simulation-based study showed that the quality of chest compressions was worse in the prone position than in the supine position. When prone chest compressions were performed using different hand and body position, prone CPR performed by a participant straddling a hospital bed with hands placed above the scapula on either side at the mid-chest level provided higher-quality chest compressions and lower rescuer fatigue.

Prone positioning of nonintubated patients with COVID-19 in Australian intensive care units

Objective

To describe the use of and outcomes from awake prone positioning (APP) in nonintubated patients with COVID-19 in Australian intensive care units (ICUs) in comparison to those who did not receive APP, and to explore the temporal relationship between publication of APP research and changes in clinical practice.

Design

Multicentre, observational cohort study.

Setting

Seventy-eight Australian ICUs participating in SPRINT-SARI Australia.

Participants

Adult patients with confirmed COVID-19 admitted to ICU from 27 February 2020 until 30 June 2022.

Main outcomes measures

Proportion of patients receiving APP, rates of invasive ventilation, hospital length of stay (LOS), in-hospital mortality.

Results

4711 patients were included in the analysis, of whom 28.6% (1347/4711) underwent APP. Use of APP rapidly increased during the Delta wave and then subsequently declined. Over this period, there were a total of 30 publications on APP. APP patients received a median of 2 (IQR 1-4) days prone positioning, were less unwell (median APACHE-II 13.0 vs. 15.0, p < 0.001), and were less likely to require invasive ventilation (27.9% vs. 34.9%, p < 0.001). Overall, there was no difference in hospital LOS (median 14 vs. 13 days, P = 0.420) or in-hospital mortality (HR 0.95, 0.8-1.11) in those that did and did not receive APP. However, in patients requiring invasive ventilation after their first day in the ICU, not receiving APP was associated with earlier time to intubation (median 1 vs. 3 days, p < 0.001) and lower adjusted in-hospital mortality (HR 0.70, CI 0.54-0.90).

Conclusions

APP was rapidly adopted into practice within Australian ICUs during the COVID-19 pandemic at the same time as a growing number of publications on the topic. A lower frequency of invasive ventilation was noted with APP overall, but in those who eventually required this intervention, APP was associated with greater risk-adjusted in-hospital mortality.

Effectiveness and safety of adjunctive non-drug measures in improving respiratory symptoms among patients with severe COVID-19: A multicenter randomized controlled trial

BACKGROUND

The outbreak of coronavirus disease 2019 (COVID-19) infection posed a huge threat and burden to public healthcare in late 2022. Non-drug measures of traditional Chinese medicine (TCM), such as acupuncture, cupping and moxibustion, are commonly used as adjuncts in China to help in severe cases, but their effects remain unclear.

OBJECTIVES

To observe the clinical effect of TCM non-drug measures in improving respiratory function and symptoms among patients with severe COVID-19.

DESIGN, SETTING, PARTICIPANTS AND INTERVENTIONS

This study was designed as a multicenter, assessor-blind, randomized controlled trial. Hospitalized patients with COVID-19 were randomly assigned to the treatment or control group. The treatment group received individualized TCM non-drug measures in combination with prone position ventilation, while the control group received prone position ventilation only for 5 consecutive days.

MAIN OUTCOME MEASURES

The primary outcome measures were the percentage of patients with improved oxygen saturation (SpO2) at the end of the 5-day intervention, as well as changes of patients' respiratory rates. The secondary outcome measures included changes in SpO2 and total score on the self-made respiratory symptom scale. The improvement rate, defined as a 3-day consecutive increase in SpO2, the duration of prone positioning, and adverse events were recorded as well.

RESULTS

Among the 198 patients included in the intention-to-treat analysis, 159 (80.3%) completed all assessments on day 5, and 39 (19.7%) patients withdrew from the study. At the end of the intervention, 71 (91%) patients in the treatment group had SpO2 above 93%, while 61 (75.3%) in the control group reached this level. The proportion of participant with improved SpO2 was significantly greater in the intervention group (mean difference [MD] = 15.7; 95% confidence interval [CI]: 4.4, 27.1; P = 0.008). Compared to the baseline, with daily treatment there were significant daily decreases in respiratory rates in both groups, but no statistical differences between groups were found (all P ≥ 0.05). Compared to the control group, the respiratory-related symptoms score was lower among patients in the treatment group (MD = -1.7; 95% CI: -2.8, -0.5; P = 0.008) after day 3 of treatment. A gradual decrease in the total scores of both groups was also observed. Thirty-one adverse events occurred during the intervention, and 2 patients were transferred to the intensive care unit due to deterioration of their illness.

CONCLUSION

TCM non-drug measures combined with prone positioning can effectively treat patients with severe COVID-19. The combined therapy significantly increased SpO2 and improved symptom scores compared to prone positioning alone, thus improving the patients' respiratory function to help them recover. However, the improvement rate did not differ between the two groups.

TRIAL REGISTRATION

Chinese Clinical Trial Registry (ChiCTR2300068319). Please cite this article as: Yin X, Jin Z, Li F, Huang L, Hu YM, Zhu BC, Wang ZQ, Li XY, Li JP, Lao LX, Mi YQ, Xu SF. Effectiveness and safety of adjunctive non-drug measures in improving respiratory symptoms among patients with severe COVID-19: A multicenter randomized controlled trial. J Integr Med. 2024; 22(6): 637-644.

Oxygen therapy and noninvasive respiratory supports in acute hypoxemic respiratory failure: a narrative review

BACKGROUND

This narrative review was written by an expert panel to the members of the jury to help in the development of clinical practice guidelines on oxygen therapy.

RESULTS

According to the expert panel, acute hypoxemic respiratory failure was defined as PaO2 < 60 mm Hg or SpO2 < 90% on room air, or PaO2/FiO2 ≤ 300 mm Hg. Supplemental oxygen should be administered according to the monitoring of SpO2, with the aim at maintaining SpO2 above 92% and below 98%. Noninvasive respiratory supports are generally reserved for the most hypoxemic patients with the aim of relieving dyspnea. High-flow nasal cannula oxygen (HFNC) seems superior to conventional oxygen therapy (COT) as a means of avoiding intubation and may therefore be should probably be used as a first-line noninvasive respiratory support in patients requiring more than 6 L/min of oxygen or PaO2/FiO2 ≤ 200 mm Hg and a respiratory rate above 25 breaths/minute or clinical signs of respiratory distress, but with no benefits on mortality. Continuous positive airway pressure (CPAP) cannot currently be recommended as a first-line noninvasive respiratory support, since its beneficial effects on intubation remain uncertain. Despite older studies favoring noninvasive ventilation (NIV) over COT, recent clinical trials fail to show beneficial effects with NIV compared to HFNC. Therefore, there is no evidence to support the use of NIV or CPAP as first-line treatment if HFNC is available. Clinical trials do not support the hypothesis that noninvasive respiratory supports may lead to late intubation. The potential benefits of awake prone positioning on the risk of intubation in patients with COVID-19 cannot be extrapolated to patients with another etiology.

CONCLUSIONS

Whereas oxygen supplementation should be initiated for patients with acute hypoxemic respiratory failure defined as PaO2 below 60 mm Hg or SpO2 < 90% on room air, HFNC should be the first-line noninvasive respiratory support in patients with PaO2/FiO2 ≤ 200 mm Hg with increased respiratory rate. Further studies are needed to assess the potential benefits of CPAP, NIV through a helmet and awake prone position in patients with acute hypoxemic respiratory failure not related to COVID-19.

Efficacy and Safety of Dexmedetomidine in the Prone Position in Elderly Patients with Pneumonia: A Prospective, Double-Blind, Randomized Controlled Study

PURPOSE

We aimed to identify a safe and effective method to assist older adults with pneumonia in tolerating the prone position for a longer duration.

METHODS

This was a randomized, controlled, double-blinded study performed at the Shanghai Fourth People's Hospital. Eighty patients with pneumonia aged ≥ 65 years were included. The patients were able to spontaneous breath in the prone position and were administered intravenous dexmedetomidine or an isotonic sodium chloride solution. The cumulative daily durations of prone positioning for all patients in the two groups were recorded. The primary outcome was the percentage of patients who completed ≥ 9 h/day in the prone position. The secondary outcomes included the incidence of complications in the prone position and patient outcomes.

RESULTS

Eighty patients were included (average age: 79.6 ± 8.9 years). The percentage of patients who completed ≥ 9 h/day in the prone position was significantly higher in the dexmedetomidine group than in the placebo group (P = 0.011). The percentage of patients who completed ≥ 12 h/day in the prone position was also significantly greater in the dexmedetomidine group than in the placebo group (P = 0.008). There were no significant differences in other variables between the two groups.

CONCLUSIONS

The results of this study demonstrate that intravenous dexmedetomidine injection can significantly prolong the duration of spontaneous breathing in the prone position in elderly pneumonia patients without obvious adverse events. We provide a safe and effective method to help patients with pneumonia, especially those with delirium or cognitive impairment, who cannot tolerate the length of time needed for spontaneous breathing in the prone position to be effective.

TRIAL REGISTRATION

The study was registered with the Chinese Clinical Trial Center (registration number: ChiCRT2300067383) on 2023-01-05.

Awake pronation with helmet CPAP in early COVID-19 ARDS patients: effects on respiratory effort and distribution of ventilation assessed by EIT

Prone positioning with continuous positive airway pressure (CPAP) is widely used for respiratory support in awake patients with COVID-19-associated acute respiratory failure. We aimed to assess the respiratory mechanics and distribution of ventilation in COVID-19-associated ARDS treated by CPAP in awake prone position. We studied 16 awake COVID-19 patients with moderate-to-severe ARDS. The study protocol consisted of a randomized sequence of supine and prone position with imposed positive end-expiratory pressure (PEEP) of 5 and 10 cmH2O delivered by helmet CPAP. Respiratory mechanics and distribution of ventilation were assessed through esophageal pressure (PES) and electrical impedance tomography (EIT). At the end of each 20-min phase, arterial blood gas analysis was performed, and PES swing and EIT tracings were recorded for the calculation of the respiratory mechanics and regional ventilation. The patient's position had no significant effects on respiratory mechanics. EIT analysis did not detect differences among global indices of ventilation. A significant proportion of pixels in the sternal region of interest showed an increase in compliance from the supine to prone position and PaO2/FIO2 increased accordingly. The best improvement of both PaO2/FIO2 and sternal compliance was obtained in the prone position with PEEP 10 cmH2O. In the studied subjects, prone positioning during CPAP treatment raised oxygenation without improvement of "protective" ventilation or global ventilatory inhomogeneity indices. Prone positioning with higher PEEP significantly increased the compliance of sternal regions.

Duration of the first prone positioning maneuver and its association with 90-day mortality in patients with acute respiratory failure due to COVID-19: A retrospective study of time terciles

OBJECTIVE

To investigate the association between the duration of the first prone positioning maneuver (PPM) and 90-day mortality in patients with C-ARDS.

DESIGN

Retrospective, observational, and analytical study.

SETTING

COVID-19 ICU of a tertiary hospital.

PATIENTS

Adults over 18 years old, with a confirmed diagnosis of SARS-CoV-2 disease requiring PPM.

INTERVENTIONS

Multivariable analysis of 90-day survival.

MAIN VARIABLES OF INTEREST

Duration of the first PPM, number of PPM sessions, 90-day mortality.

RESULTS

271 patients undergoing PPM were analyzed: first tertile (n = 111), second tertile (n = 95) and third tertile (n = 65). The results indicated that the median duration of PDP was 14 h (95% CI: 10-16 h) in the first tertile, 19 h (95% CI: 18-20 h) in the second tertile and 22 h (95% CI: 21-24 h) in the third tertile. Comparison of survival curves using the Logrank test did not reach statistical significance (p = 0.11). Cox Regression analysis showed an association between the number of pronation sessions (patients receiving between 2 and 5 sessions (HR = 2.19; 95% CI: 1.07-4.49); and those receiving more than 5 sessions (HR = 6.05; 95% CI: 2.78-13.16) and 90-day mortality.

CONCLUSIONS

while the duration of PDP does not appear to significantly influence 90-day mortality, the number of pronation sessions is identified as a significant factor associated with an increased risk of mortality.

Prolonged vs shorter awake prone positioning for COVID-19 patients with acute respiratory failure: a multicenter, randomised controlled trial

PURPOSE

Awake prone positioning has been reported to reduce endotracheal intubation in patients with coronavirus disease 2019 (COVID-19)-related acute hypoxemic respiratory failure (AHRF). However, it is still unclear whether using the awake prone positioning for longer periods can further improve outcomes.

METHODS

In this randomized, open-label clinical trial conducted at 12 hospitals in China, non-intubated patients with COVID-19-related AHRF were randomly assigned to prolonged awake prone positioning (target > 12 h daily for 7 days) or standard care with a shorter period of awake prone positioning. The primary outcome was endotracheal intubation within 28 days after randomization. The key secondary outcomes included mortality and adverse events.

RESULTS

In total, 409 patients were enrolled and randomly assigned to prolonged awake prone positioning (n = 205) or standard care (n = 204). In the first 7 days after randomization, the median duration of prone positioning was 12 h/d (interquartile range [IQR] 12-14 h/d) in the prolonged awake prone positioning group vs. 5 h/d (IQR 2-8 h/d) in the standard care group. In the intention-to-treat analysis, intubation occurred in 35 (17%) patients assigned to prolonged awake prone positioning and in 56 (27%) patients assigned to standard care (relative risk 0.62 [95% confidence interval (CI) 0.42-0.9]). The hazard ratio (HR) for intubation was 0.56 (0.37-0.86), and for mortality was 0.63 (0.42-0.96) for prolonged awake prone positioning versus standard care, within 28 days. The incidence of pre-specified adverse events was low and similar in both groups.

CONCLUSION

Prolonged awake prone positioning of patients with COVID-19-related AHRF reduces the intubation rate without significant harm. These results support prolonged awake prone positioning of patients with COVID-19-related AHRF.

Effect of the prone position on mechanical power in elective surgical patients under general anesthesia: A prospective observational study

OBJECTIVES

To evaluate how the prone position influences mechanical power (MP) during elective surgical procedures.

METHODS

In this prospective study carried out at Karadeniz Ereğli Government Hospital, Zonguldak, Turkey, from January 2024 to February 2024, 76 patients under general anesthesia were evaluated at different time points during the surgical procedure. Hemodynamic, laboratory, and mechanical ventilation data were also recorded.

RESULTS

The MP increased in the prone position at the beginning of surgery. Transitioning to the supine position at the end of surgery led to a decrease in MP. At the end of surgery, the mean MP in supine and prone positions was found to be higher compared to those measured in the first hour of surgery. Mechanical power and body mass index (BMI) exhibited a significant positive correlation.

CONCLUSION

Position changes influence MP. Returning to the prone position increases MP. An increase in BMI is associated with an increase in MP.ANZCTR Reg. No.: ACTRN12623001281684.

A Proof of Concept Study on the Comfort and Usability of a Supportive Pillow for Pregnant Patients with COVID-19 Acute Respiratory Distress Syndrome

Background

The prone position has been seen to benefit patients experiencing acute respiratory distress syndrome. However, performing this position in pregnant patients has been difficult and raises safety concerns.

Objective

The current study aimed to test the use of a supportive pillow (Prone Pillow for Pregnant Patients or 4P) to address concerns regarding pregnant patients in prone position.

Methods

The study prospectively evaluated the use of the prone pillow for patient comfort and usability among healthcare workers with qualitative and quantitative measures.

Results

A total of three patients were recruited alongside 16 healthcare workers assisting pregnant patients to the prone position. Overall, awake pregnant patients found the pillow to be comfortable while healthcare workers perceived the pillow to be useful in improving quality of care among awake and intubated pregnant patients.

CONCLUSION

The 4P is a potentially useful and beneficial product in placing pregnant patients in the prone position during episodes of acute respiratory distress. However, due to the limited sample size, more clinical trials are needed to evaluate the impact of this innovation in improving patient and healthcare worker safety.

The prone position in COVID-19 impacts the thickness of peripapillary retinal nerve fiber layers and macular ganglion cell layers

The prone position reduces mortality in severe cases of COVID-19 with acute respiratory distress syndrome. However, visual loss and changes to the peripapillary retinal nerve fiber layer (p-RNFL) and the macular ganglion cell layer and inner plexiform layer (m-GCIPL) have occurred in patients undergoing surgery in the prone position. Moreover, COVID-19-related eye problems have been reported. This study compared the p-RNFL and m-GCIPL thicknesses of COVID-19 patients who were placed in the prone position with patients who were not. This prospective longitudinal and case-control study investigated 15 COVID-19 patients placed in the prone position (the "Prone Group"), 23 COVID-19 patients not in the prone position (the "Non-Prone Group"), and 23 healthy, non-COVID individuals without ocular disease or systemic conditions (the "Control Group"). The p-RNFL and m-GCIPL thicknesses of the COVID-19 patients were measured at 1, 3, and 6 months and compared within and between groups. The result showed that the Prone and Non-Prone Groups had no significant differences in their p-RNFL thicknesses at the 3 follow-ups. However, the m-GCIPL analysis revealed significant differences in the inferior sector of the Non-Prone Group between months 1 and 3 (mean difference, 0.74 μm; P = 0.009). The p-RNFL analysis showed a significantly greater thickness at 6 months for the superior sector of the Non-Prone Group (131.61 ± 12.08 μm) than for the Prone Group (118.87 ± 18.21 μm; P = 0.039). The m-GCIPL analysis revealed that the inferior sector was significantly thinner in the Non-Prone Group than in the Control Group (at 1 month 80.57 ± 4.60 versus 83.87 ± 5.43 μm; P = 0.031 and at 6 months 80.48 ± 3.96 versus 83.87 ± 5.43 μm; P = 0.044). In conclusion, the prone position in COVID-19 patients can lead to early loss of p-RNFL thickness due to rising intraocular pressure, which is independent of the timing of prone positioning. Consequently, there is no increase in COVID-19 patients' morbidity burden.

Worse survival in patients with right ventricular dysfunction and COVID-19-associated acute respiratory distress requiring extracorporeal membrane oxygenation: A multicenter study from the ORACLE Group

OBJECTIVE

We sought to determine the impact of right ventricular dysfunction on the outcomes of mechanically ventilated patients with COVID-19 requiring veno-venous extracorporeal membrane oxygenation.

METHODS

Six academic centers conducted a retrospective analysis of mechanically ventilated patients with COVID-19 stratified by support with veno-venous extracorporeal membrane oxygenation during the first wave of the pandemic (March to August 2020). Echocardiograms performed for clinical indications were reviewed for right and left ventricular function. Baseline characteristics, hospitalization characteristics, and survival were compared.

RESULTS

The cohort included 424 mechanically ventilated patients with COVID-19, 126 of whom were cannulated for veno-venous extracorporeal membrane oxygenation. Right ventricular dysfunction was observed in 38.1% of patients who received extracorporeal membrane oxygenation and 27.4% of patients who did not receive extracorporeal membrane oxygenation with an echocardiogram. Biventricular dysfunction was observed in 5.5% of patients who received extracorporeal membrane oxygenation. Baseline patient characteristics were similar in both the extracorporeal membrane oxygenation and non-extracorporeal membrane oxygenation cohorts stratified by the presence of right ventricular dysfunction. In the extracorporeal membrane oxygenation cohort, right ventricular dysfunction was associated with increased inotrope use (66.7% vs 24.4%, P < .001), bleeding complications (77.1% vs 53.8%, P = .015), and worse survival independent of left ventricular dysfunction (39.6% vs 64.1%, P = .012). There was no significant difference in days ventilated before extracorporeal membrane oxygenation, length of hospital stay, hours on extracorporeal membrane oxygenation, duration of mechanical ventilation, vasopressor use, inhaled pulmonary vasodilator use, infectious complications, clotting complications, or stroke. The cohort without extracorporeal membrane oxygenation cohort demonstrated no statistically significant differences in in-hospital outcomes.

CONCLUSIONS

The presence of right ventricular dysfunction in patients with COVID-19-related acute respiratory distress syndrome supported with veno-venous extracorporeal membrane oxygenation was associated with increased in-hospital mortality. Additional studies are required to determine if mitigating right ventricular dysfunction in patients requiring veno-venous extracorporeal membrane oxygenation improves mortality.

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.

Predictors of in-hospital mortality in elderly unvaccinated patients during SARS-CoV-2 Alpha variants epidemic

Background

COVID-19, caused by SARS-CoV-2, has caused a global pandemic. This study aimed to identify predictors of in-hospital mortality in unvaccinated elderly patients with COVID-19 by comparing various predictive factors between the survivors and non-survivors.

Methods

We retrospectively selected 132 unvaccinated patients aged over 65 years with COVID-19 at a hospital in Kanagawa, Japan, during SARS-CoV-2 Alpha variants epidemic. We compared the clinical characteristics, laboratory and radiological findings, treatment, and complications of the survivors and non-survivors. In logistic regression analysis, variables that were significant in the univariate analysis were subjected to multivariate analysis using the variable increase method.

Results

There were 119 and 13 patients in the survivor and non-survivor groups, respectively. Multivariate regression revealed increasing odds with the presence of ARDS and DIC (odd ratio (OR) = 16.35, 34.36; P=0.002, 0.001, respectively) and prolonged hospital stay (OR = 1.17; P=0.004).

Conclusions

We found the complications of ARDS and DIC and hospital length of stay to be independent predictors of in-hospital mortality in elderly unvaccinated patients with COVID-19. Establishing treatments and prevention methods for ARDS and DIC could result in lower mortality rates.

Prone positioning in awake patients without ventilatory support does not alter major clinical outcomes in severe COVID-19: results from a retrospective observational cohort study, systematic review and meta-analysis

OBJECTIVES

During the Coronavirus disease (COVID-19) pandemic, clinicians recommended awake-prone positioning (APP) to avoid the worst outcomes. The objectives of this study were to investigate if APP reduces intubation, death rates, and hospital length of stay (HLOS) in acute COVID-19.

METHODS

We performed a retrospective cohort with non-mechanically ventilated patients hospitalized in a reference center in Manaus, Brazil, 2020. Participants were stratified into APP and awake-not-prone positioning (ANPP) groups. Also, we conducted a systematic review and performed a meta-analysis to understand if this intervention had different outcomes in resource-limited settings (PROSPERO CRD42023422452).

RESULTS

A total of 115 participants were allocated into the groups. There was no statistical difference between both groups regarding time to intubation (HR: 0.861; 95CI: 0.474-1.1562; p=0.622) and time to death (HR: 1.666; 95CI: 0.939-2.951; p=0.081). APP was not significantly associated with reduced HLOS. A total of 86 articles were included in the systematic review, of which 76 (88,3%) show similar findings after APP. Also, low/middle, and high-income countries were similar regarding such outcomes.

CONCLUSION

APP in COVID-19 does not present clinical improvement that affects mortality, intubation rate and HLOS. The lack of a prone position protocol, obtained through a controlled study, is necessary. After 3 years, APP benefits are still inconclusive.

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.

PEEP-Induced Lung Recruitment Maneuver Combined with Prone Position for ARDS: A Single-Center, Prospective, Randomized Clinical Trial

Background: Prone position (PP) and the positive end-expiratory pressure (PEEP)-induced lung recruitment maneuver (LRM) are both efficient in improving oxygenation and prognosis in patients with ARDS. The synergistic effect of PP combined with PEEP-induced LRM in patients with ARDS remains unclear. We aim to explore the effects of PP combined with PEEP-induced LRM on prognosis in patients with moderate to severe ARDS and the predicting role of lung recruitablity. Methods: Patients with moderate to severe ARDS were consecutively enrolled. The patients were prospectively assigned to either the intervention (PP with PEEP-induced LRM) or control groups (PP). The clinical outcomes, respiratory mechanics, and electric impedance tomography (EIT) monitoring results for the two groups were compared. Lung recruitablity (recruitment-to-inflation ratio: R/I) was measured during the PEEP-induced LRM procedure and was used for predicting the response to LRM. Results: Fifty-eight patients were included in the final analysis, among which 28 patients (48.2%) received PEEP-induced LRM combined with PP. PEEP-induced LRM enhanced the effect of PP by a significant improvement in oxygenation (∆PaO2/FiO2 75.8 mmHg vs. 4.75 mmHg, p < 0.001) and the compliance of respiratory system (∆Crs, 2 mL/cmH2O vs. -1 mL/cmH2O, p = 0.02) among ARDS patients. Based on the EIT measurement, PP combined with PEEP-induced LRM increased the ventilation distribution mainly in the dorsal region (5.0% vs. 2.0%, p = 0.015). The R/I ratio was measured in 28 subjects. The higher R/I ratio was related to greater oxygenation improvement after LRM (Pearson's r = 0.4; p = 0.034). Conclusions: In patients with moderate to severe ARDS, PEEP-induced LRM combined with PP can improve oxygenation and dorsal ventilation distribution. R/I can be useful to predict responses to LRM.

Prone positioning effect on tracheal intubation rate, mortality and oxygenation parameters in awake non-intubated severe COVID-19-induced respiratory failure: a review of reviews

BACKGROUND

Prone positioning (PP) is a low-cost method with minimal risk to the patient that improves the oxygenation of patients with acute hypoxic respiratory failure (AHRF) due to COVID-19 pneumonia, thereby reducing their need for tracheal intubation (TI) and transferring to the intensive care unit (ICU). We aimed to overview the results of all previous systematic reviews and meta-analyses to examine the net effect of PP on oxygenation, the rate of TI and mortality in COVID-19 patients.

METHODS

We searched PubMed, Scopus, Web of Science, Google Scholar, and Cochrane Library databases from December 2019 through 2022 without publication language restriction for systematic reviews and meta-analysis studies on PP vs. supine position (SP) in conscious patients with hypoxic respiratory failure COVID-19. After study selection, data were extracted from published meta-analyses and pooled by comprehensive meta-analysis (CMA) software version 2.2.064 to achieve effect sizes. They were analyzed for TI and mortality rates dichotomous variables, and the results were shown as pooled odds ratios (OR) with a 95% confidence interval (CI). Continuous variables such as oxygenation indices (PaO2/FiO2 and SpO2) were also analyzed, and the data were shown as mean differences (MD) with lower and upper CI. The level of statistical significance was set at p ≤ 0.05.

RESULTS

Twelve systematic reviews and meta-analyses with 19,651 patients and six systematic reviews with 2,911 patients were included in this Review of Reviews (total: 22,562). PP treatment significantly reduced the rate of TI (OR = 0.639, %95 CI (0.492, 0.829); P-value = 0.001) and decreased mortality (OR = 0.363, %95 CI (0.240, 0.549), P-value < 0.001). There was no difference in PaO2/FiO2 (MD = 3.591[- 40.881, 48.062]; P-value = 0.874) and SpO2 percent (MD = 1.641[- 4.441, 7.723]; P-value = 0.597).

CONCLUSION

Prone positioning can be recommended in conscious ICU patients with COVID-19 pneumonia to reduce mortality and intubation.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration number: CRD42022326951. Registered 25 April 2022.

Awake prone positioning for patients with COVID-19-related respiratory failure: a systematic review and meta-analysis

The role of awake prone positioning (aPP) in patients with acute hypoxemic respiratory failure is debated. We performed a systematic review and meta-analysis to evaluate the role of aPP in acute respiratory failure related to COronaVIrus Disease-19 (COVID-19). Studies reporting on the clinical course of patients with acute respiratory failure related to COVID-19 treated or not treated by aPP were included in the systematic review and meta-analysis (ProsperoID: CRD42022333211). The primary study outcome was the composite of in-hospital death or orotracheal intubation; the individual components of the primary outcome were secondary study outcomes. The composite of in-hospital death or orotracheal intubation was available for 6 studies (1884 patients), five randomized and one prospective; a significant reduction in the risk of this outcome was observed in patients treated vs. not treated by aPP (33.5% vs. 39.8%; OR 0.73, 95% CI 0.60-0.89; I2 0%). In-hospital death was reported in 34 studies (6808 patients) and occurred in 17.4% vs. 23.5% of patients treated or not treated with aPP (random effect OR 0.60, 95% CI 0.46-0.79; I2 59%); orotracheal intubation was observed in 25.8% vs. 32.7% of patients treated or not treated with aPP (27 studies, 5369 patients; random effect OR 0.85, 95% CI 0.56-1.27; I2 84%). aPP reduces the risk for death or orotracheal intubation in patients with acute respiratory failure related to COVID-19. Further studies should be conducted to confirm the clinical benefit of aPP outside the ICU.Registration Prospero ID: CRD42022333211.

Prone positioning during CPAP therapy in SARS-CoV-2 pneumonia: a concise clinical review

During the COVID-19 pandemic, the number of patients with hypoxemic acute respiratory failure (ARF) due to SARS-CoV-2 pneumonia threatened to overwhelm intensive care units. To reduce the need for invasive mechanical ventilation (IMV), clinicians tried noninvasive strategies to manage ARF, including the use of awake prone positioning (PP) with continuous positive airway pressure (CPAP). In this article, we review the patho-physiologic rationale, clinical effectiveness and practical issues of the use of PP during CPAP in non-intubated, spontaneously breathing patients affected by SARS-CoV-2 pneumonia with ARF. Use of PP during CPAP appears to be safe and feasible and may have a lower rate of adverse events compared to IMV. A better response to PP is observed among patients in early phases of acute respiratory distress syndrome. While PP during CPAP may improve oxygenation, the impact on the need for intubation and mortality remains unclear. It is possible to speculate on the role of PP during CPAP in terms of improvement of ventilation mechanics and reduction of strain stress.

Qualitative study of COVID-19 patient experiences with non-invasive ventilation and pronation: strategies to enhance treatment adherence

INTRODUCTION

Non-invasive ventilation (NIV) treatment combined with pronation in patients with COVID-19 respiratory failure has been shown to be effective in improving respiratory function and better patient outcomes. These patients may experience discomfort or anxiety that may reduce adherence to treatment.

OBJECTIVE

The aim of this study was to explore and describe the subjective experiences of patients undergoing helmet NIV and pronation during hospitalisation for COVID-19 respiratory failure, with a focus on the elements of care and strategies adopted by patients that enabled good adaptation to treatments.

METHOD

A qualitative descriptive study, using face-to-face interviews, was carried out with a purposeful sample of 20 participants discharged from a pulmonary intensive care unit who underwent helmet continuous positive airway pressure and pronation during hospitalisation for COVID-19.

RESULTS

Content analysis of the transcripts revealed feelings and experiences related to illness and treatments, strategies for managing one's own negative thoughts, and practical strategies of one's own and healthcare workers to facilitate adaptation to pronation and helmet. Experience was reflected in five major topics related to specific time points and settings: feelings and experiences, helmet and pronation: heavy but beneficial, positive thinking strategies, patients' practical strategies, support of healthcare professionals (HCPs).

CONCLUSIONS

This study may be useful to HCPs to improve the quality and appropriateness of care they provide.

Effectiveness and safety of a new helmet CPAP configuration allowing tidal volume monitoring in patients with COVID-19

BACKGROUND

High generated tidal volumes (Vt) have been correlated with higher risk of self-induced lung injury and worse clinical outcome. This study aimed to evaluate the effectiveness and safety of a new helmet continuous positive airway pressure delivered (h-CPAP) configuration allowing Vt monitoring in patients affected by COVID-19.

METHODS

This prospective observational study was performed in the respiratory intermediate care unit of University Hospital in Turin, Italy, between March 24th, and June 15th, 2020. Included patients were treated with CPAP via a single-limb intentional leak configuration by a turbine-driven ventilator, provided with a dedicated patch. Effectiveness and safety of the configuration and healthcare workers safety were the outcomes of the study.

MAIN FINDINGS

Thirty-five patients were included in this study. Median age was 67 years (IQR 57-76 years), and 30 patients (85.7%) were men. Median value of overall leaks (intentional plus unintentional) was 68 L/min (IQR 63-75). Reliability of Vt measurements was 100%. An out of scale of Vt (above 50% compared to the previous values) was never recorded. Six patients (17.1%) needed more than two helmet replacements, due to leak test >10 l/min. Arm oedema and skin breakdowns were reported in sixteen (45.7%) and seven (20%) patients respectively. Among the 63 healthcare workers involved in the care of COVID-19 patients during the study only one was positive at RT-PCR nasopharyngeal swab testing.

CONCLUSIONS

The use of h-CPAP for treating COVID-19 in this configuration allowed for reliable Vt monitoring. Further studies evaluating this configuration in larger patients' cohorts are needed.

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.

Acute myocardial infarction from a lower-middle income country-A comprehensive report on performance measures and quality metrics using National Cardiovascular Data Registry

INTRODUCTION

Epidemic of cardiovascular disease (CVD) is widely projected in South Asian population and estimated to get double in two decades. Ischemic heart disease (IHD) is one of the spectrums of CVD and acute myocardial infarction (AMI) being the common manifestations of IHD. National Cardiovascular Data Registry (NCDR) is a registry data that measure their practices and improve quality of care. In this project we aim to see our performance trends in the care of IHD including AMI patients over two year's period.

MATERIAL & METHODS

A cross sectional study conducted at the Aga Khan University Hospital, Karachi, Pakistan. All patients aged 18 years and above admitted to adult Cardiology units with chest pain and acute coronary syndrome are eligible to be included in NCDR data set. Data on demographics and initial characteristics of patients were extracted from NCDR institutional dataset. The data was then compared between 2019 and 2020 on performance, quality, and efficiency metrics.

RESULT

In 2019 to 2020, 1542 patients with acute coronary syndrome and stable ischemic heart disease were admitted. Out of these, 1042 patients (67.8%) were males. According to our data, the 2020 mortality rate was about 5.25%. In 2019 and 2020, bleeding rates were 1.1% and 1.6%, respectively. Our data showed 100% PCI in 90 minutes in 2019 while 87% in 2020. According to the appropriateness criteria for PCI, 80% were appropriate, while 20% were possibly appropriate in both years. The median length of stay following a procedure was 2 days in 2019 and 1 day in 2020.

CONCLUSION

This study described the common and unique characteristics of patients with myocardial infarction representing population from South Asian region. Overall, the procedural performance measure and outcome metrics are up to the international benchmarks. Cultural, financial, and pandemic effects identified certain challenges.

Risk Factors for the Impairment of Ambulation in Older People Hospitalized with COVID-19: A Retrospective Cohort Study

(1) Background: Some older people hospitalized with COVID-19 have experienced reduced ambulation capacity. However, the prevalence of the impairment of ambulation capacity still needs to be established. Objective: To estimate the prevalence of, and identify the risk factors associated with, the impairment of ambulation capacity at the point of hospital discharge for older people with COVID-19. (2) Methods: A retrospective cohort study. Included are those with an age > 60 years, of either sex, hospitalized due to COVID-19. Clinical data was collected from patients' medical records. Ambulation capacity prior to COVID-19 infection was assessed through the patients' reports from their relatives. Multiple logistic regressions were performed to identify the risk factors associated with the impairment of ambulation at hospital discharge. (3) Results: Data for 429 older people hospitalized with COVID-19 were randomly collected from the medical records. Among the 56.4% who were discharged, 57.9% had reduced ambulation capacity. Factors associated with reduced ambulation capacity at discharge were a hospital stay longer than 20 days (Odds Ratio (OR): 3.5) and dependent ambulation capacity prior to COVID-19 (Odds Ratio (OR): 11.3). (4) Conclusion: More than half of the older people who survived following hospitalization due to COVID-19 had reduced ambulation capacity at hospital discharge. Impaired ambulation prior to the infection and a longer hospital stay were risks factors for reduced ambulation capacity.

Effects of awake-prone positioning on oxygenation and physiological outcomes in non-intubated patients with COVID-19: A randomized controlled trial

BACKGROUND

Prone positioning is a well-known supportive approach for increasing oxygenation and reducing mortality in non-COVID-19 patients with moderate to severe acute respiratory distress syndrome. However, studies highlighting the effects of proning in patients with COVID-19 are limited.

AIM

To investigate the effects of awake-prone positioning (APP) on oxygenation and physiological outcomes in non-intubated patients with COVID-19.

STUDY DESIGN

A randomized controlled trial was carried out with two parallel groups at 1:1 ratio. Adult awake non-intubated patients with confirmed COVID-19, non-rebreathing face mask or continuous positive airway pressure, PaO2 /FiO2 ratio ≤150 mmHg were randomly assigned to the APP group or control group. The control group was subjected to conventional positioning interventions. Outcome measures were PaO2 /FiO2 ratio, ROX index, PaO2 , PaCO2 , SaO2 , respiratory rate, blood pressure, and shock index. These parameters were recorded immediately before positioning, 10 min after patient positioning, and 1 h after patient positioning.

RESULTS

Of 115 patients assessed for eligibility, 82 were randomized to the APP group or control group (41 patients in each group). The use of APP for non-intubated patients with COVID-19 resulted in statistically significant improvements in oxygenation parameters, that is, SpO2 , PaO2 /FiO2 , ROX index, PaO2 , and SaO2 , at the three study time points (p = .000, .007, .000, .011, and .000 respectively). The SpO2 was increased to 92.15 ± 2.735 mmHg for the APP group versus 88.17 ± 4.847 for the control group after 1 h of patients' positioning. The PaO2 /FiO2 ratio increased in the APP group before proning compared with 1 h after proning (79.95 ± 22.508 vs. 98.91 ± 34.44) respectively. APP improved the SpO2 , PaO2 /FiO2 , ROX index, PaO2 , and SaO2 values for the APP group, representing an increase of 5.85%, 23.71%, 30.79%, 22.59%, and 5.26%, respectively.

CONCLUSION

Awake proning in non-intubated patients with COVID-19 showed marked improvement in oxygenation and physiological parameters.

RELEVANCE TO CLINICAL PRACTICE

This study provides evidence for critical care nurses to implement APP in non-intubated patients with COVID-19 to improve oxygenation and physiological parameters, as it was tolerated by most of the patients without serious adverse events.

[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.

Knowledge, attitudes, and practice related to the prone positioning of patients among intensive care unit nurses working in COVID-19 units: A cross-sectional study in China

BACKGROUND

An increasing number of studies persistently demonstrate that prone position ventilation can significantly improve the oxygenation index and blood oxygen saturation for most patients (70-80%) with acute respiratory distress syndrome (ARDS). Studies have also shown that the awake prone position was both safe and effective in helping patients with coronavirus disease 2019 (COVID-19) breathe spontaneously. However, the prone position is not widely adopted when treating patients with COVID-19 or ARDS from other causes. Basic knowledge, positive attitudes, and correct practices among the nursing staff are necessary to increase the use of prone positions, reduce the incidence of complications associated with prone positions, and improve the quality and safety of health care.

AIM

This study aimed to investigate the knowledge, attitudes, and practice of prone positioning of patients among intensive care unit (ICU) nurses working in COVID-19 units and provide suggestions for improvement.

STUDY DESIGN

ICU nurses were recruited from two designated tertiary hospitals for COVID-19 treatment in Shanghai, China, in April 2022, using convenience sampling. A questionnaire survey focusing on the dimensions of knowledge, attitudes, and practice of the prone position with 42 items, was conducted.

RESULTS

A total of 132 ICU nurses participated. The scores on the overall questionnaire and the dimensions of knowledge, attitudes, and practice of prone position were 167.28 (95% CI, 161.70-172.86), 78.35 (95% CI, 76.04-80.66), 32.08 (95% CI, 31.51-32.65), and 56.85 (95% CI, 52.42-61.28) respectively. The overall average score was 79.66% (95% CI, 0.77-0.82). The results of multiple linear regression analysis showed that prior experience in treating patients with COVID-19 and professional titles were related to the level of knowledge, attitudes, and practice of prone position.

CONCLUSIONS

The ICU nurses strongly believed in the effectiveness of prone positioning, but their knowledge and practice levels need improvement. The experience in treating patients with COVID-19 and professional titles were related to the level of knowledge, attitudes, and practice of prone position. Nursing managers should ensure that ICU nurses are well trained in prone positioning and help enhance the knowledge and attitudes toward prone positioning to promote its widespread use.

RELEVANCE TO CLINICAL PRACTICE

Clinical guidelines and in-service training modules need to be developed to promote the use of prone positioning and reduce prone position-related complications.

The physiological effect of prone positioning and lateral decubitus in non-intubated patients with severe COVID-19: a prospective cohort study

Introduction

Prone positioning is one type of postural lung recruitment manoeuvre that has been widely studied regarding the benefits and physiological changes of the cardiorespiratory system. However, prone positioning is not very comfortable for the patients because they have to lie on their stomachs for a while when the oxygen therapy and other monitoring devices are still attached. Based on patient observations, some patients will change to more comfortable positions, namely using the right/left lateral decubitus position. The purpose of this research was to examine the physiological impact of prone and lateral decubitus position in non-intubated patients who were diagnosed with severe COVID-19.

Methods

It was a prospective cohort study in subsequent people with severe COVID-19 who obtained a non-rebreathing mask or high-flow nasal cannula at a University Hospital between 1 June and 10 September 2021. The study lasted for a total of 2021 days and involved 48 patients. The patients assumed the prone positioning or lateral decubitus every morning and afternoon for 4 h and were measured for cardiorespiratory parameters and blood gas analysis. It has been reported in line with the STROCSS criteria.

Results

Dynamic changes based on cardiorespiratory parameters and blood gas analysis parameters in patients with prone and lateral decubitus position in patients with severe COVID-19 receiving conventional oxygen therapy (via non-rebreathing mask) or high-flow nasal cannula did not show any significant difference.

Conclusion

The physiological effect of prone positioning and lateral decubitus in non-intubated patients with severe COVID-19 are similar. Accordingly, lateral decubitus can be an alternative for postural lung recruitment manoeuvres and warrants further randomized trials.

Effect of awake prone positioning on tracheal intubation rates in patients with COVID-19: A meta-analysis

Purpose

We investigated the effect of awake prone positioning on endotracheal intubation rates in spontaneously breathing patients with COVID-19 not undergoing endotracheal intubation.

Methods

We searched the CINAHL, Cochrane Library, PUBMED, MEDLINE, and Web of Science databases until December 31, 2022. Prospective randomized controlled, cohort, and case-control studies were included. A meta-analysis was performed on the primary outcome measure, tracheal intubation rates, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

Results

Ten studies with a total of 2641 patients were included. The tracheal intubation rate in the awake prone position was 34% (95%CI: 0.59-1.10; P = 0.18; I2 = 55%), showing a non-significant benefit. Mortality was lower in prone-positioned than in supine-positioned patients (odds ratio: 0.75; 95% CI: 0.61-0.93; P = 0.007; I2 = 46%), prone positioning significantly improved the PaO2/FiO2 ratio (mean difference -29.17; 95%CI: -50.91 to -7.43; P = 0.009; I2 = 44%).

Conclusions

Prone positioning can improve the PaO2/FIO2 ratio in patients with COVID-19 but we found no significant effect on tracheal intubation rates. Awake prone positioning seems to be associated with lower mortality, however, and may thus be a beneficial and effective intervention for patients with COVID-19. The optimal timing, duration, and target population need to be determined in future studies.

Physiological effects of awake prone position in acute hypoxemic respiratory failure

BACKGROUND

The effects of awake prone position on the breathing pattern of hypoxemic patients need to be better understood. We conducted a crossover trial to assess the physiological effects of awake prone position in patients with acute hypoxemic respiratory failure.

METHODS

Fifteen patients with acute hypoxemic respiratory failure and PaO2/FiO2 < 200 mmHg underwent high-flow nasal oxygen for 1 h in supine position and 2 h in prone position, followed by a final 1-h supine phase. At the end of each study phase, the following parameters were measured: arterial blood gases, inspiratory effort (ΔPES), transpulmonary driving pressure (ΔPL), respiratory rate and esophageal pressure simplified pressure-time product per minute (sPTPES) by esophageal manometry, tidal volume (VT), end-expiratory lung impedance (EELI), lung compliance, airway resistance, time constant, dynamic strain (VT/EELI) and pendelluft extent through electrical impedance tomography.

RESULTS

Compared to supine position, prone position increased PaO2/FiO2 (median [Interquartile range] 104 mmHg [76-129] vs. 74 [69-93], p < 0.001), reduced respiratory rate (24 breaths/min [22-26] vs. 27 [26-30], p = 0.05) and increased ΔPES (12 cmH2O [11-13] vs. 9 [8-12], p = 0.04) with similar sPTPES (131 [75-154] cmH2O s min-1 vs. 105 [81-129], p > 0.99) and ΔPL (9 [7-11] cmH2O vs. 8 [5-9], p = 0.17). Airway resistance and time constant were higher in prone vs. supine position (9 cmH2O s arbitrary units-3 [4-11] vs. 6 [4-9], p = 0.05; 0.53 s [0.32-61] vs. 0.40 [0.37-0.44], p = 0.03). Prone position increased EELI (3887 arbitrary units [3414-8547] vs. 1456 [959-2420], p = 0.002) and promoted VT distribution towards dorsal lung regions without affecting VT size and lung compliance: this generated lower dynamic strain (0.21 [0.16-0.24] vs. 0.38 [0.30-0.49], p = 0.004). The magnitude of pendelluft phenomenon was not different between study phases (55% [7-57] of VT in prone vs. 31% [14-55] in supine position, p > 0.99).

CONCLUSIONS

Prone position improves oxygenation, increases EELI and promotes VT distribution towards dependent lung regions without affecting VT size, ΔPL, lung compliance and pendelluft magnitude. Prone position reduces respiratory rate and increases ΔPES because of positional increases in airway resistance and prolonged expiratory time. Because high ΔPES is the main mechanistic determinant of self-inflicted lung injury, caution may be needed in using awake prone position in patients exhibiting intense ΔPES. Clinical trail registeration: The study was registered on clinicaltrials.gov (NCT03095300) on March 29, 2017.