The latest guidelines for the hospital care of patients affected by coronavirus disease 2019 (COVID-19)-related acute respiratory failure have moved towards the widely accepted use of noninvasive respiratory support (NIRS) as opposed to early intubation at the pandemic onset. The establishment of severe COVID-19 pneumonia goes through different pathophysiological phases that partially resemble typical acute respiratory distress syndrome (ARDS) and have been categorized into different clinical–radiological phenotypes. These can variably benefit on the application of external positive end-expiratory pressure (PEEP) during noninvasive mechanical ventilation, mainly due to variable levels of lung recruitment ability and lung compliance during different phases of the disease. A growing body of evidence suggests that intense respiratory effort producing excessive negative pleural pressure swings (Ppl) plays a critical role in the onset and progression of lung and diaphragm damage in patients treated with noninvasive respiratory support. Routine respiratory monitoring is mandatory to avoid the nasty continuation of NIRS in patients who are at higher risk for respiratory deterioration and could benefit from early initiation of invasive mechanical ventilation instead. Here we propose different monitoring methods both in the clinical and experimental settings adapted for this purpose, although further research is required to allow their extensive application in clinical practice. We reviewed the needs and available tools for clinical–physiological monitoring that aims at optimizing the ventilatory management of patients affected by acute respiratory distress syndrome due to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection.

/pdf/different-methods-to-improve-the-monitoring-of-noninvasive-2uy20xe9.pdf

Different Methods to Improve the Monitoring of Noninvasive Respiratory Support of Patients with Severe Pneumonia/ARDS Due to COVID-19: An Update

A significant proportion of patients with COVID-19 pneumonia could develop acute respiratory distress syndrome (ARDS), thus requiring mechanical ventilation, and resulting in a high rate of intensive care unit (ICU) admission. Several complications can arise during an ICU stay, from both COVID-19 infection and the respiratory supporting system, including barotraumas (pneumothorax and pneumomediastinum), superimposed pneumonia, coagulation disorders (pulmonary embolism, venous thromboembolism, hemorrhages and acute ischemic stroke), abdominal involvement (acute mesenteric ischemia, pancreatitis and acute kidney injury) and sarcopenia. Imaging plays a pivotal role in the detection and monitoring of ICU complications and is expanding even to prognosis prediction. The present pictorial review describes the clinicopathological and radiological findings of COVID-19 ARDS in ICU patients and discusses the imaging features of complications related to invasive ventilation support, as well as those of COVID-19 itself in this particularly fragile population. Radiologists need to be familiar with COVID-19’s possible extra-pulmonary complications and, through reliable and constant monitoring, guide therapeutic decisions. Moreover, as more research is pursued and the pathophysiology of COVID-19 is increasingly understood, the role of imaging must evolve accordingly, expanding from the diagnosis and subsequent management of patients to prognosis prediction.

/pdf/an-imaging-overview-of-covid-19-ards-in-icu-patients-and-its-q551dg2v.pdf

An Imaging Overview of COVID-19 ARDS in ICU Patients and Its Complications: A Pictorial Review

Spontaneous pneumomediastinum (SP) has been described early during the COVID-19 pandemic in large series of patients with severe pneumonia, but most patients were receiving invasive mechanical ventilation (IMV) at the time of SP diagnosis. In this retrospective multicenter observational study, we aimed at describing the prevalence and outcomes of SP during severe COVID-19 with pneumonia before any IMV, to rule out mechanisms induced by IMV in the development of pneumomediastinum.Among 549 patients, 21 patients (4%) developed a SP while receiving non-invasive respiratory support, after a median of 6 days [4-12] from ICU admission. The proportion of patients requiring IMV was similar. However, the time to tracheal intubation was longer in patients with SP (6 days [5-13] vs. 2 days [1-4]; P = 0.00002), with a higher first-line use of non-invasive ventilation (n = 11; 52% vs. n = 150; 28%; P = 0.02). The 21 patients who developed a SP had persisting signs of severe lung disease and respiratory failure with lower ROX index between ICU admission and occurrence of SP (3.94 [3.15-5.55] at admission vs. 3.25 [2.73-4.02] the day preceding SP; P = 0.1), which may underline potential indirect signals of Patient-self inflicted lung injury (P-SILI).In this series of critically ill COVID-19 patients, the prevalence of SP without IMV was not uncommon, affecting 4% of patients. They received more often vasopressors and had a longer ICU length of stay, as compared with their counterparts. One pathophysiological mechanism may potentially be carried out by P-SILI related to a prolonged respiratory failure, as underlined by a delayed use of IMV and the evolution of the ROX index between ICU admission and the day preceding SP. 

/pdf/spontaneous-pneumomediastinum-a-surrogate-of-p-sili-in-2bm9ljyw.pdf

Spontaneous pneumomediastinum: a surrogate of P-SILI in critically ill COVID-19 patients

Background The role of excessive inspiratory effort in promoting alveolar and pleural rupture resulting in air leak (AL) in patients with SARS-CoV-2 induced acute respiratory failure (ARF) while on spontaneous breathing is undetermined. Methods Among all patients with COVID-19 related ARF admitted to a respiratory intensive care unit (RICU) and receiving non-invasive respiratory support, those developing an AL were and matched 1:1 [by means of PaO2/FiO2 ratio, age, body mass index-BMI and subsequent organ failure assessment (SOFA)] with a comparable population who did not (NAL group). Esophageal pressure (ΔPes) and dynamic transpulmonary pressure (ΔPL) swings were compared between groups. Risk factors affecting AL onset were evaluated. The composite outcome of ventilator-free-days (VFD) at day 28 (including ETI, mortality, tracheostomy) was compared between groups. Results Air leak and NAL groups (n = 28) showed similar ΔPes, whereas AL had higher ΔPL (20 [16–21] and 17 [11–20], p = 0.01, respectively). Higher ΔPL (OR = 1.5 95%CI[1–1.8], p = 0.01), positive end-expiratory pressure (OR = 2.4 95%CI[1.2–5.9], p = 0.04) and pressure support (OR = 1.8 95%CI[1.1–3.5], p = 0.03), D-dimer on admission (OR = 2.1 95%CI[1.3–9.8], p = 0.03), and features suggestive of consolidation on computed tomography scan (OR = 3.8 95%CI[1.1–15], p = 0.04) were all significantly associated with AL. A lower VFD score resulted in a higher risk (HR = 3.7 95%CI [1.2–11.3], p = 0.01) in the AL group compared with NAL. RICU stay and 90-day mortality were also higher in the AL group compared with NAL. Conclusion In spontaneously breathing patients with COVID-19 related ARF, higher levels of ΔPL, blood D-dimer, NIV delivery pressures and a consolidative lung pattern were associated with AL onset.

Risk Factors for Pulmonary Air Leak and Clinical Prognosis in Patients With COVID-19 Related Acute Respiratory Failure: A Retrospective Matched Control Study

PNX was described as an uncommon complication in COVID-19 patients but clinical risk predictors and the potential role in patient's outcome are still unclear. We assessed prevalence, risk predictors and mortality of PNX in hospitalized COVID- 19 with severe respiratory failure performing a retrospective observational analysis of 184 patients admitted to our COVID-19 Respiratory Unit in Vercelli from October 2020 to March 2021. We compared patients with and without PNX reporting prevalence, clinical and radiological features, comorbidities, and outcomes. Prevalence of PNX was 8.1% and mortality was >86% (13/15) significantly higher than in patients without PNX (56/169) (P < 0.001). PNX was more likely to occur in patients with a history of cognitive decline (HR: 31.18) who received non-invasive ventilation (NIV) (p < 0.0071) and with low P/F ratio (HR: 0.99, p = 0.004). Blood chemistry in the PNX subgroup compared to patients without PNX showed a significant increase in LDH (420 U/L vs 345 U/L, respectively p = 0.003), ferritin (1111 mg/dl vs 660 mg/dl, respectively p = 0.006) and decreased lymphocytes (HR: 4.440, p = 0.004). PNX may be associated with a worse prognosis in terms of mortality in COVID patients. Possible mechanisms may include the hyperinflammatory status associated with critical illness, the use of NIV, the severity of respiratory failure and cognitive impairment. We suggest, in selected patients showing low P/F ratio, cognitive impairment and metabolic cytokine storm, an early treatment of systemic inflammation in association with high-flow oxygen therapy as a safer alternative to NIV in order to avoid fatalities connected with PNX. 

http://www.resmedjournal.com/article/S0954611123000823/pdf

Pneumothorax in hospitalized COVID-19 patients with severe respiratory failure: Risk factors and outcome

Pneumothorax (PNX) and pneumomediastinum (PNM) are potential complications of COVID-19, but their influence on patients’ outcomes remains unclear. The aim of the study was to assess incidence, risk factors, and outcomes of severe COVID-19 complicated with PNX/PNM. Methods: A retrospective multicenter case-control analysis was conducted in COVID-19 patients admitted for respiratory failure in intermediate care units of the Treviso area, Italy, from March 2020 to April 2021. Clinical characteristics and outcomes of patients with and without PNX/PNM were compared. Results: Among 1213 patients, PNX and/or PNM incidence was 4.5%. Among these, 42% had PNX and PNM, 33.5% only PNX, and 24.5% only PNM. COVID-19 patients with PNX/PNM showed higher in-hospital (p = 0.02) and 90-days mortality (p = 0.048), and longer hospitalization length (p = 0.002) than COVID-19 patients without PNX/PNM. At PNX/PNM occurrence, one-third of subjects was not mechanically ventilated, and the respiratory support was similar to the control group. PNX/PNM occurrence was associated with longer symptom length before hospital admission (p = 0.005) and lower levels of blood lymphocytes (p = 0.017). Conclusion: PNX/PNM are complications of COVID-19 associated with a worse prognosis in terms of mortality and length of hospitalization. Although they are more frequent in ventilated patients, they can occur in non-ventilated, suggesting that mechanisms other than barotrauma might contribute to their presentation.

Pneumothorax and/or Pneumomediastinum Worsens the Prognosis of COVID-19 Patients with Severe Acute Respiratory Failure: A Multicenter Retrospective Case-Control Study in the North-East of Italy.

Vito Catalanotti

Papers

Pneumothorax and/or Pneumomediastinum Worsens the Prognosis of COVID-19 Patients with Severe Acute Respiratory Failure: A Multicenter Retrospective Case-Control Study in the North-East of Italy.

The role of imaging in COVID-19 pneumonia diagnosis and management: Main positions of the experts, key imaging features and open answers