Hypoxemia and prone position in mechanically ventilated COVID-19 patients: a prospective cohort study

Role of narrow band imaging in assessing bronchial mucosal hypervascularization in COVID-19 patients

BACKGROUND

SARS-CoV-2 virus which targets the lung vasculature is supposed to affect both pulmonary and bronchial arteries. This study evaluated the tracheobronchial vascularization density observed with narrow band imaging (NBI) in patients hospitalized for COVID-19 pneumonia. To determine if the observed changes were specific of COVID-19 patients, the procedure was also performed in non-COVID-19 patients.

METHODS

Thirty patients included in this monocentric, prospective study underwent videobronchoscopy using both white light and NBI: 10 with a COVID-19 infection, 10 with a non-COVID-19 pulmonary infection and 10 with a peripheral pulmonary nodule. The tracheobronchial vascular density observed through NBI was rated by two blinded pneumologists at three levels (carina, right main bronchus and left main bronchus).

RESULTS

When compared to the two other groups, a significant increase of the tracheobronchial vascularization was found in COVID-19 patients. The median tracheobronchial vascularization global score obtained with NBI (out of 15 points) was: 10 [9 - 13] in the COVID-19 group, 5 [4 - 10] in the non-COVID-19 group (p < 0.001) and 6 in the Nodule group [4 - 9] (p = 0.002). Using a weighted Cohen's Kappa coefficient, we observed a good agreement between the two raters for the evaluation of the tracheobronchial vascularization score (κ = 0.75 [0.65-0.83]); p < 0.001).

CONCLUSION

Videobronchoscopy with NBI in COVID-19 patients showed diffuse changes in tracheobronchial vascularization. We suggest that such bronchial hypervascularisation with dilated vessels contributes, at least in part, to the intrapulmonary right to left shunt that characterized the COVID-19 related Acute Vascular Distress Syndrome (AVDS).

Early Prone Position Ventilation in the Efficacy for Severe Hypoxemia and Neurological Complications Following Acute Type A Aortic Dissection (TAAD) Surgery

OBJECTIVE

To analyze the efficacy of early prone position ventilation in the treatment of severe hypoxemia after surgery for acute type A aortic dissection (TAAD).

METHODS

The patients were divided into a control group and a treatment group. Parameters assessed included blood gas analysis indicators [arterial oxygen partial pressure (PaO2).

RESULTS

(1) Blood gas analysis: Before treatment, there was no significant difference in PaO2, SpO2, and OI levels between the two groups; after treatment, the PaO2, SpO2, and OI levels in both groups significantly increased compared to pre-treatment, with a more pronounced improvement in the treatment group than in the control group (p < 0.05). (2) Hemodynamics: Before treatment, there was no significant difference in MAP and HR levels between the two groups; after treatment, the MAP levels increased significantly in both groups compared to pre-treatment, while HR levels decreased significantly, with no significant difference between the groups. (3) Prognosis recovery: MV time, ICU stay, and total hospital stay were significantly lower in the treatment group than in the control group; the 30-day mortality rate was 14.58% in the control group and 12.50% in the treatment group, with no significant difference in 30-day mortality rate between the groups.

CONCLUSION

Early prone position ventilation has shown promising application in the treatment of severe hypoxemia after TAAD surgery. Compared to traditional supine position ventilation, the use of early prone position ventilation can further improve blood gas analysis indicators in patients, and shorten MV time, ICU stay, and total hospital stay, thereby accelerating patient recovery.

Pathophysiology of Hypoxemia in COVID-19 Lung Disease

As the pandemic has progressed, our understanding of hypoxemia in coronavirus disease 2019 (COVID-19) lung disease has become more nuanced, although much remains to be understood. In this article, we review ventilation-perfusion mismatching in COVID-19 and the evidence to support various biologic theories offered in explanation. In addition, the relationship between hypoxemia and other features of severe COVID-19 lung disease such as respiratory symptoms, radiographic abnormalities, and pulmonary mechanics is explored. Recognizing and understanding hypoxemia in COVID-19 lung disease remains essential for risk stratification, prognostication, and choice of appropriate treatments in severe COVID-19.

Prone ventilation in intubated COVID-19 patients: a systematic review and meta-analysis

BACKGROUND

The efficacy and safety profiles of prone ventilation among intubated Coronavirus Disease 2019 (COVID-19) patients remain unclear. The primary objective was to examine the effect of prone ventilation on the ratio of arterial partial pressure of oxygen to fraction of inspired oxygen (PaO2/FiO2) in intubated COVID-19 patients.

METHODS

Databases of MEDLINE, EMBASE and CENTRAL were systematically searched from inception until March 2021. Case reports and case series were excluded.

RESULTS

Eleven studies (n = 606 patients) were eligible. Prone ventilation significantly improved PaO2/FiO2 ratio (studies: 8, n = 579, mean difference 46.75, 95% CI 33.35‒60.15, p < 0.00001; evidence: very low) and peripheral oxygen saturation (SpO2) (studies: 3, n = 432, mean difference 1.67, 95% CI 1.08‒2.26, p < 0.00001; evidence: ow), but not the arterial partial pressure of carbon dioxide (PaCO2) (studies: 5, n = 396, mean difference 2.45, 95% CI 2.39‒7.30, p = 0.32; evidence: very low), mortality rate (studies: 1, n = 215, Odds Ratio 0.66, 95% CI 0.32‒1.33, p = 0.24; evidence: very low), or number of patients discharged alive (studies: 1, n = 43, Odds Ratio 1.49, 95% CI 0.72‒3.08, p = 0.28; evidence: very low).

CONCLUSION

Prone ventilation improved PaO2/FiO2 ratio and SpO2 in intubated COVID-19 patients. Given the substantial heterogeneity and low level of evidence, more randomized- controlled trials are warranted to improve the certainty of evidence, and to examine the adverse events of prone ventilation.

Effectiveness of prone position in acute respiratory distress syndrome and moderating factors of obesity class and treatment durations for COVID-19 patients: A Meta-Analysis

Objectives

To examine the effectiveness of prone positioning on COVID-19 patients with acute respiratory distress syndrome with moderating factors in both traditional prone positioning (invasive mechanical ventilation) and awake self-prone positioning patients (non-invasive ventilation).

Research methodology

A comprehensive search was conducted in CINAHL, Cochrane library, Embase, Medline-OVID, NCBI SARS-CoV-2 Resources, ProQuest, Scopus, and Web of Science without language restrictions. All studies with prospective and experimental designs evaluating the effect of prone position patients with COVID-19 related to acute respiratory distress syndrome were included. Pooled standardised mean differences were calculated after prone position for primary (PaO₂/FiO₂) and secondary outcomes (SpO₂ and PaO₂)

Results

A total of 15 articles were eligible and included in the final analysis. Prone position had a statistically significant effect in improving PaO₂/FiO₂ with standardised mean difference of 1.10 (95%CI 0.60–1.59), SpO₂ with standardised mean difference of 3.39 (95% CI 1.30–5.48), and PaO₂ with standardised mean difference of 0.77 (95% CI 0.19–1.35). Patients with higher body mass index and longer duration/day are associated with larger standardised mean difference effect sizes for prone positioning.

Conclusions

Our findings demonstrate that prone position significantly improved oxygen saturation in COVID-19 patients with acute respiratory distress syndrome in both traditional prone positioning and awake self-prone positioning patients. Prone position should be recommended for patients with higher body mass index and longer durations to obtain the maximum effect.

Prone position in COVID 19-associated acute respiratory failure

PURPOSE OF REVIEW

Prone position has been widely used in the COVID-19 pandemic, with an extension of its use in patients with spontaneous breathing ('awake prone'). We herein propose a review of the current literature on prone position in mechanical ventilation and while spontaneous breathing in patients with COVID-19 pneumonia or COVID-19 ARDS.

RECENT FINDINGS

A literature search retrieved 70 studies separating whether patient was intubated (24 studies) or nonintubated (46 studies). The outcomes analyzed were intubation rate, mortality and respiratory response to prone. In nonintubated patient receiving prone position, the main finding was mortality reduction in ICU and outside ICU setting.

SUMMARY

The final results of the several randomized control trials completed or ongoing are needed to confirm the trend of these results. In intubated patients, observational studies showed that responders to prone in terms of oxygenation had a better survival than nonresponders.

Hemodynamic response to positive end-expiratory pressure and prone position in COVID-19 ARDS

Background

Use of high positive end-expiratory pressure (PEEP) and prone positioning is common in patients with COVID-19-induced acute respiratory failure. Few data clarify the hemodynamic effects of these interventions in this specific condition. We performed a physiologic study to assess the hemodynamic effects of PEEP and prone position during COVID-19 respiratory failure.

Methods

Nine adult patients mechanically ventilated due to COVID-19 infection and fulfilling moderate-to-severe ARDS criteria were studied. Respiratory mechanics, gas exchange, cardiac output, oxygen consumption, systemic and pulmonary pressures were recorded through pulmonary arterial catheterization at PEEP of 15 and 5 cmH₂O, and after prone positioning. Recruitability was assessed through the recruitment-to-inflation ratio.

Results

High PEEP improved PaO₂/FiO₂ ratio in all patients (p = 0.004), and significantly decreased pulmonary shunt fraction (p = 0.012), regardless of lung recruitability. PEEP-induced increases in PaO2/FiO2 changes were strictly correlated with shunt fraction reduction (rho=-0.82, p = 0.01). From low to high PEEP, cardiac output decreased by 18 % (p = 0.05) and central venous pressure increased by 17 % (p = 0.015).

As compared to supine position with low PEEP, prone positioning significantly decreased pulmonary shunt fraction (p = 0.03), increased PaO₂/FiO₂ (p = 0.03) and mixed venous oxygen saturation (p = 0.016), without affecting cardiac output. PaO₂/FiO₂ was improved by prone position also when compared to high PEEP (p = 0.03).

Conclusions

In patients with moderate-to-severe ARDS due to COVID-19, PEEP and prone position improve arterial oxygenation. Changes in cardiac output contribute to the effects of PEEP but not of prone position, which appears the most effective intervention to improve oxygenation with no hemodynamic side effects.

Case Reports: Bronchial Mucosal Vasculature Is Also Involved in the Acute Vascular Distress Syndrome of COVID-19

Background: The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) which targets the pulmonary vasculature is supposed to induce an intrapulmonary right to left shunt with an increased pulmonary blood flow. We report here what may be, to the best of our knowledge, the first videoendoscopic descriptions of an hypervascularization of the bronchial mucosa in two patients hospitalized for coronavirus disease 2019 (COVID-19) pneumonia. Cases Presentation: Two patients, 27- and 37-year-old, were addressed to our Pneumology department for suspicion of COVID-19 pneumonia. Their symptoms (fever, dry cough, and dyspnoea), associated to pulmonary ground glass opacities on thoracic CT, were highly suggestive of a COVID-19 disease despite repeated negative pharyngeal swabs RT-PCR. In both patients, bronchoscopy examination using white light was unremarkable but NBI bronchoscopy revealed a diffuse hypervascularization of the mucosa from the trachea to the sub-segmental bronchi, associated with dilated submucosal vessels. RT-PCR performed in bronchoalveolar lavage (BAL) confirmed the presence of Sars-CoV-2. Conclusions: These two case reports highlight the crucial importance of the vascular component of the viral disease. We suggest that such bronchial hypervascularization with dilated vessels contributes, at least in part, to the intrapulmonary right to left shunt that characterizes the COVID-19 related Acute Vascular Distress Syndrome (AVDS). The presence of diffuse bronchial hypervascularization in the context of COVID-19 pandemic should prompt the search for Sars-CoV-2 in BAL samples.

Effect of prone positioning on oxygenation and static respiratory system compliance in COVID-19 ARDS vs. non-COVID ARDS

Background

Prone positioning is recommended for patients with moderate-to-severe acute respiratory distress syndrome (ARDS) receiving mechanical ventilation. While the debate continues as to whether COVID-19 ARDS is clinically different from non-COVID ARDS, there is little data on whether the physiological effects of prone positioning differ between the two conditions. We aimed to compare the physiological effect of prone positioning between patients with COVID-19 ARDS and those with non-COVID ARDS.

Methods

We retrospectively compared 23 patients with COVID-19 ARDS and 145 patients with non-COVID ARDS treated using prone positioning while on mechanical ventilation. Changes in PaO₂/FiO₂ ratio and static respiratory system compliance (Crs) after the first session of prone positioning were compared between the two groups: first, using all patients with non-COVID ARDS, and second, using subgroups of patients with non-COVID ARDS matched 1:1 with patients with COVID-19 ARDS for baseline PaO₂/FiO₂ ratio and static Crs. We also evaluated whether the response to the first prone positioning session was associated with the clinical outcome.

Results

When compared with the entire group of patients with non-COVID ARDS, patients with COVID-19 ARDS showed more pronounced improvement in PaO₂/FiO₂ ratio [adjusted difference 39.3 (95% CI 5.2–73.5) mmHg] and static Crs [adjusted difference 3.4 (95% CI 1.1–5.6) mL/cmH₂O]. However, these between-group differences were not significant when the matched samples (either PaO₂/FiO₂-matched or compliance-matched) were analyzed. Patients who successfully discontinued mechanical ventilation showed more remarkable improvement in PaO₂/FiO₂ ratio [median 112 (IQR 85–144) vs. 35 (IQR 6–52) mmHg, P = 0.003] and static compliance [median 5.7 (IQR 3.3–7.7) vs. − 1.0 (IQR − 3.7–3.0) mL/cmH₂O, P = 0.006] after prone positioning compared with patients who did not. The association between oxygenation and Crs responses to prone positioning and clinical outcome was also evident in the adjusted competing risk regression.

Conclusions

In patients with COVID-19 ARDS, prone positioning was as effective in improving respiratory physiology as in patients with non-COVID ARDS. Thus, it should be actively considered as a therapeutic option. The physiological response to the first session of prone positioning was predictive of the clinical outcome of patients with COVID-19 ARDS.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-021-01819-4.

Effect of prone position on respiratory parameters, intubation and death rate in COVID-19 patients: systematic review and meta-analysis

Prone position (PP) is known to improve oxygenation and reduce mortality in COVID-19 patients. This systematic review and meta-analysis aimed to determine the effects of PP on respiratory parameters and outcomes. PubMed, EMBASE, ProQuest, SCOPUS, Web of Sciences, Cochrane library, and Google Scholar were searched up to 1st January 2021. Twenty-eight studies were included. The Cochran's Q-test and I2 statistic were assessed heterogeneity, the random-effects model was estimated the pooled mean difference (PMD), and a meta-regression method has utilized the factors affecting heterogeneity between studies. PMD with 95% confidence interval (CI) of PaO2/FIO2 Ratio in before-after design, quasi-experimental design and in overall was 55.74, 56.38, and 56.20 mmHg. These values for Spo2 (Sao2) were 3.38, 17.03, and 7.58. PP in COVID-19 patients lead to significantly decrease of the Paco2 (PMD: - 8.69; 95% CI - 14.69 to - 2.69 mmHg) but significantly increase the PaO2 (PMD: 37.74; 95% CI 7.16-68.33 mmHg). PP has no significant effect on the respiratory rate. Based on meta-regression, the study design has a significant effect on the heterogeneity of Spo2 (Sao2) (Coefficient: 12.80; p < 0.001). No significant associations were observed for other respiratory parameters with sample size and study design. The pooled estimate for death rate and intubation rates were 19.03 (8.19-32.61) and 30.68 (21.39-40.75). The prone positioning was associated with improved oxygenation parameters and reduced mortality and intubation rate in COVID-19 related respiratory failure.