Pulmonary Edema: A Pictorial Review of Imaging Manifestations and Current Understanding of Mechanisms of Disease

Breath-by-breath assessment of acute pulmonary edema using electrical impedance tomography, spirometry and volumetric capnography in a sheep (Ovis Aries) model

Background

The bedside diagnosis of acute pulmonary edema is challenging. This study evaluated the breath-by-breath information from electrical impedance tomography (EIT), respiratory mechanics and volumetric capnography (VCap) to assess acute pulmonary edema induced by xylazine administration in anesthetized sheep.

Objective

To determine the ability and efficiency of each monitoring modality in detecting changes in lung function associated with onset of pulmonary edema.

Methods

Twenty healthy ewes were anesthetized, positioned in sternal (prone) recumbency and instrumented. Synchronized recordings of EIT, spirometry and VCap were performed for 60 s prior to start of injection, during xylazine injection over 60 s (0-60 s) and continuously for 1 min (60-120 s) after the end of injection. After visual assessment of the recorded mean variables, statistical analysis was performed using a mixed effect model for repeated measures with Bonferroni's correction for multiple comparisons, to determine at which breath after start of injection the variable was significantly different from baseline. A significant change over time was defined as an adjusted p < 0.05. All statistics were performed using GraphPad Prism 0.1.0.

Results

Electrical impedance tomography showed significant changes from baseline in all but two variables. These changes were observed simultaneously during xylazine injection at 48 s and were consistent with development of edema in dependent lung (decreased end-expiratory lung impedance, ventilation in centro-ventral and ventral lung region) and shift of ventilation into non-dependent lung (decreased non-dependent silent spaces and increased center of ventilation ventral to dorsal and increased ventilation in centro-dorsal and dorsal lung region). All changes in lung mechanics also occurred during injection, including decreased dynamic respiratory system compliance and increased peak expiratory flow, peak inspiratory pressure and airway resistance at 48, 54 and 60 s, respectively. Changes in VCap variables were delayed with all occurring after completion of the injection.

Conclusion

In this model of pulmonary edema, EIT detected significant and rapid change in all assessed variables of lung function with changes in regional ventilation indicative of pulmonary edema. Volumetric capnography complemented the EIT findings, while respiratory mechanics were not specific to lung edema. Thus, EIT offers the most comprehensive method for pulmonary edema evaluation, including the assessment of ventilation distribution, thereby enhancing diagnostic capabilities.

An Assessment of the Prevalence and Risk Factors of Hypertensive Crisis in Patients Who Visited the Emergency Outpatient Department (EOPD) at Adama Hospital Medical College, Adama, Oromia, Ethiopia: A 6-Month Prospective Study

Background

Over 1 billion people worldwide suffer from the common chronic medical condition of hypertension. A hypertensive crisis occurs when blood pressure exceeds 180/110 mmHg. Depending on whether the target organ is harmed, the situation may be presented as a hypertensive emergency or urgency.

Objective

To assess the prevalence and risk factors of patients with hypertensive crises who visited the Emergency Outpatient Department (EOPD) at Adama Hospital Medical College in Adama, Oromia, Ethiopia, between January 01 and August 31, 2021, G.C. Methodology. A cross-sectional, prospective study on the hypertensive crisis was conducted at Adama Hospital Medical College from January 01 to August 31, 2021, G.C. The data were collected using a standardized questionnaire, validated for completeness, and analyzed using SPSS. The findings were tabulated, and conclusions and recommendations were conveyed.

Result

Out of 9,082 patients who visited the EOPD during the six-month period, 444 individuals with hypertensive crises were identified, representing a prevalence of 4.9%. Of these, 56.8% were men, resulting in a M : F ratio of 1.31 : 1. Those between the ages of 66 and 75 were the most affected. At presentation, 91.0% of the study participants were known hypertensive patients. Among the known hypertensive patients, the majority (34.9%) were known to have been hypertensive for 5-10 years. Of the known hypertensive patients, 48.6% were found to be adherent. Hypertensive urgency was discovered to be far more common than hypertensive emergencies (63.5% vs. 36.5%). Headache was the most common presenting symptom, and most patients (36.5%) presented to the health setup in less than 24 hours. The main risk variables identified were drug discontinuation, family history of hypertension, salt consumption, and alcohol usage. The main excuse for the lack of adherence was the cost of the medications. More than half of the patients do not have any additional comorbidities, and of those who do, diabetes mellitus is the most prevalent. A stroke was identified as a major complication. Conclusions and Recommendations. Hypertensive crises are one of the most prevalent reasons for EOPD admission and are linked to significant consequences. At presentation, most of the study subjects were known hypertension patients. Diabetes mellitus was discovered to be a comorbid condition in one-quarter of them. Although more than half of the patients had improved, the death rate still remained high. Infrastructure and capacity building to provide hospitals with the requisite baseline investigations are among the government's recommendations. Health practitioners are expected to make improvements, such as by educating the public about the need for lifestyle changes and evaluating and managing any hypertension problems.

Risk factors for re-expansion pulmonary edema following chest tube drainage in patients with spontaneous pneumothorax: A systematic review and meta-analysis

Re-expansion pulmonary edema (RPE) is a rare but potentially life-threatening complication that can occur after rapid lung expansion following the management of lung collapse. This meta-analysis aimed to investigate the risk factors for RPE following chest tube drainage in patients with spontaneous pneumothorax. We conducted a comprehensive systematic literature search in electronic databases of PubMed, ScienceDirect, Cochrane Library, and ProQuest to identify studies that explore the risk factors for RPE following chest tube drainage in spontaneous pneumothorax. Pooled odds ratios (OR) or weighted mean differences (WMD) were calculated to evaluate the risk factors. Statistical analysis was conducted using Review Manager 5.3 software. Five studies involving 1.093 spontaneous pneumothorax patients were included in this meta-analysis. The pooled analysis showed that the following risk factors were significantly associated with increased risk of RPE following chest tube drainage: the presence smoking history (OR=1.94, 95% CI: 1.22-3.10, P=0.005, I2=0%), longer duration of symptoms (WMD=3.76, 95% CI: 2.07-5.45, P<0.0001, I2=30%), and larger size of pneumothorax (WMD=16.76, 95% CI: 8.88-24.64, P<0.0001, I2=78%). Age, sex, and location of pneumothorax had no significant association. In patients with spontaneous pneumothorax, the presence of smoking history, longer duration of symptoms, and larger size of pneumothorax increase the risk of development of RPE following chest tube drainage.

Pinealectomy and melatonin administration in rats: their effects on pulmonary edema induced by α-naphthylthiourea

We aimed to observe the possible effects of melatonin (MLT) deprivation (pinealectomy) and exogenous MLT administration on pulmonary edema induced by alpha-naphthylthiourea (ANTU), a toxic chemical agent, in rats. Seventy animals were assigned to seven groups: control, sham pinealectomy (PINX), PINX, ANTU (10 mg/kg intraperitoneal on day 30), ANTU + MLT (10 mg/kg/day i.p. for 30 days), ANTU + PINX, and ANTU + PINX + MLT.In this study, pleural effusion (PE) formation, lung weight/body weight (LW/BW) and PE/BW ratios (fluid accumulation and weight values in the lungs) increase detected. Pre-ANTU MLT administration led to significant decreases in PE, LW/BW, and PE/BW levels. The inhibited glutathione (GSH) and superoxide dismutase (SOD) levels and high malondialdehyde (MDA) levels that ANTU increase lipid peroxidation in the study. MLT administration eliminated oxidative stress by reducing MDA and ameliorating GSH and SOD levels.Pre-ANTU MLT administration led to a significant decrease in interleukin-1 beta (IL-1β) and tumor necrosis factor-alpha (TNF-α) levels in the lung when compared to the ANTU group without MLT administration. Post-pinealectomy ANTU administration significantly increased IL-1β and TNF-α levels when compared to ANTU and MLT administration without pinealectomy. Diffused inflammatory cell infiltration, interstitial pulmonary edema, and histopathological congestion were observed after the administration of ANTU. Severity of the damage was elevated in the ANTU + PINX group. MLT treatment regressed pulmonary effusion and edema and improves lung structure. In brief, the findings suggested that MLT inhibited proinflammatory mediators and could serve as a therapeutic agent to prevent inflammatory disorders.

Noninvasive Imaging Methods for Quantification of Pulmonary Edema and Congestion: A Systematic Review

Quantification of pulmonary edema and congestion is important to guide diagnosis and risk stratification, and to objectively evaluate new therapies in heart failure. Herein, we review the validation, diagnostic performance, and clinical utility of noninvasive imaging modalities in this setting, including chest x-ray, lung ultrasound (LUS), computed tomography (CT), nuclear medicine imaging methods (positron emission tomography [PET], single photon emission CT), and magnetic resonance imaging (MRI). LUS is a clinically useful bedside modality, and fully quantitative methods (CT, MRI, PET) are likely to be important contributors to a more accurate and precise evaluation of new heart failure therapies and for clinical use in conjunction with cardiac imaging. There are only a limited number of studies evaluating pulmonary congestion during stress. Taken together, noninvasive imaging of pulmonary congestion provides utility for both clinical and research assessment, and continued refinement of methodologic accuracy, validation, and workflow has the potential to increase broader clinical adoption.

CT Approach to Lung Injury

Diffuse alveolar damage (DAD), which represents the pathologic changes seen after acute lung injury, is caused by damage to all three layers of the alveolar wall and can ultimately result in alveolar collapse with loss of the normal pulmonary architecture. DAD has an acute phase that predominantly manifests as airspace disease at CT owing to filling of the alveoli with cells, plasma fluids, and hyaline membranes. DAD then evolves into a heterogeneous organizing phase, with mixed airspace and interstitial disease characterized by volume loss, architectural distortion, fibrosis, and parenchymal loss. Patients with DAD have a severe clinical course and typically require prolonged mechanical ventilation, which may result in ventilator-induced lung injury. In those patients who survive DAD, the lungs will remodel over time, but most will have residual findings at chest CT. Organizing pneumonia (OP) is a descriptive term for a histologic pattern characterized by intra-alveolar fibroblast plugs. The significance and pathogenesis of OP are controversial. Some authors regard it as part of a spectrum of acute lung injury, while others consider it a marker of acute or subacute lung injury. At CT, OP manifests with various forms of airspace disease that are most commonly bilateral and relatively homogeneous in appearance at individual time points. Patients with OP most often have a mild clinical course, although some may have residual findings at CT. In patients with DAD and OP, imaging findings can be combined with clinical information to suggest the diagnosis in many cases, with biopsy reserved for difficult cases with atypical findings or clinical manifestations. To best participate in the multidisciplinary approach to patients with lung injury, radiologists must not only recognize these entities but also describe them with consistent and meaningful terminology, examples of which are emphasized in the article. © RSNA, 2023 See the invited commentary by Kligerman et al in this issue. Quiz questions for this article are available in the supplemental material.

Diagnosing Lung Abnormalities Related to Heart Failure in Chest Radiogram, Lung Ultrasound and Thoracic Computed Tomography

Heart failure (HF) is a multidisciplinary disease affecting almost 1-2% of the adult population worldwide. Symptoms most frequently reported by patients suffering from HF include dyspnoea, cough or exercise intolerance, which is equally often observed in many pulmonary diseases. The spectrum of lung changes related to HF is wide. The knowledge of different types of these abnormalities is essential to distinguish patients with HF from patients with lung diseases or both disorders and thus avoid unnecessary diagnostics or therapies. In this review, we aimed to summarise recent research concerning the spectrum of lung abnormalities related to HF in three frequently used lung imaging techniques: chest X-ray (CXR), lung ultrasound (LUS) and chest computed tomography (CT). We discussed the most prevalent abnormalities in the above-mentioned investigations in the context of consecutive pathophysiological stages identified in HF: (i) redistribution, (ii) interstitial oedema, and (iii) alveolar oedema. Finally, we compared the utility of these imaging tools in the clinical setting. In conclusion, we consider LUS the most useful and promising imaging technique due to its high sensitivity, repeatability and accessibility. However, the value of CXR and chest CT is their potential for establishing a differential diagnosis.

Lung Dysfunction and Chronic Kidney Disease: A Complex Network of Multiple Interactions

Chronic kidney disease (CKD) is a progressive disease that affects > 10% of the total population worldwide or >800 million people. CKD poses a particularly heavy burden in low- and middle-income countries, which are least able to cope with its consequences. It has become one of the leading causes of death worldwide and is one of the few non-communicable diseases where the number of related deaths has increased over the last two decades. The high number of people affected, and the significant negative impact of CKD should be a reason to increase efforts to improve prevention and treatment. The interaction of lung and kidney leads to highly complex and difficult clinical scenarios. CKD significantly affects the physiology of the lung by altering fluid homeostasis, acid-base balance and vascular tone. In the lung, haemodynamic disturbances lead to the development of alterations in ventilatory control, pulmonary congestion, capillary stress failure and pulmonary vascular disease. In the kidney, haemodynamic disturbances lead to sodium and water retention and the deterioration of renal function. In this article, we would like to draw attention to the importance of harmonising the definitions of clinical events in pneumology and renal medicine. We would also like to highlight the need for pulmonary function tests in routine clinical practise for the management of patients with CKD, in order to find new concepts for pathophysiological based disease-specific management strategies.

siRNA-Mediated Timp1 Silencing Inhibited the Inflammatory Phenotype during Acute Lung Injury

Acute lung injury is a complex cascade process that develops in response to various damaging factors, which can lead to acute respiratory distress syndrome. Within this study, based on bioinformatics reanalysis of available full-transcriptome data of acute lung injury induced in mice and humans by various factors, we selected a set of genes that could serve as good targets for suppressing inflammation in the lung tissue, evaluated their expression in the cells of different origins during LPS-induced inflammation, and chose the tissue inhibitor of metalloproteinase Timp1 as a promising target for suppressing inflammation. We designed an effective chemically modified anti-TIMP1 siRNA and showed that Timp1 silencing correlates with a decrease in the pro-inflammatory cytokine IL6 secretion in cultured macrophage cells and reduces the severity of LPS-induced acute lung injury in a mouse model.

Imaging drug delivery to the lungs: Methods and applications in oncology

Direct delivery to the lung via inhalation is arguably one of the most logical approaches to treat lung cancer using drugs. However, despite significant efforts and investment in this area, this strategy has not progressed in clinical trials. Imaging drug delivery is a powerful tool to understand and develop novel drug delivery strategies. In this review we focus on imaging studies of drug delivery by the inhalation route, to provide a broad overview of the field to date and attempt to better understand the complexities of this route of administration and the significant barriers that it faces, as well as its advantages. We start with a discussion of the specific challenges for drug delivery to the lung via inhalation. We focus on the barriers that have prevented progress of this approach in oncology, as well as the most recent developments in this area. This is followed by a comprehensive overview of the different imaging modalities that are relevant to lung drug delivery, including nuclear imaging, X-ray imaging, magnetic resonance imaging, optical imaging and mass spectrometry imaging. For each of these modalities, examples from the literature where these techniques have been explored are provided. Finally the different applications of these technologies in oncology are discussed, focusing separately on small molecules and nanomedicines. We hope that this comprehensive review will be informative to the field and will guide the future preclinical and clinical development of this promising drug delivery strategy to maximise its therapeutic potential.

Bilateral Upper Lobe Pulmonary Oedema and Primary Mitral Regurgitation

Pulmonary oedema of uncertain aetiology is a diagnostic challenge to clinicians worldwide. Many indicators are proposed to differentiate between cardiogenic and non-cardiogenic pulmonary oedema. Mixed pulmonary oedema is an overlap between high hydrostatic pressure and increased permeability at the microvascular level. In our case, a 77-year-old patient presented with a nine-day history of shortness of breath. He was hypoxemic in the emergency department, had a pan-systolic murmur on auscultation, and blood results showed raised inflammatory markers without any fever. His chest X-ray and computed tomography pulmonary angiogram showed asymmetric pulmonary oedema in bilateral superior lobes and bilateral pleural effusions. Point-of-care echocardiography revealed severe mitral regurgitation. Trans-oesophageal echocardiography confirmed mitral valve prolapse with the chordae rupture and systolic vein reversal flow seen in the right superior pulmonary vein. He was treated with antibiotics and diuretics. After starting intravenous diuretics, there was a rapid symptomatic improvement, and a repeat chest X-ray showed significant improvements. We concluded that it was a case of mixed pulmonary oedema with predominant cardiac aetiology, and he was referred to cardiothoracic surgery for mitral valve replacement. The case showed that mixed pulmonary oedema with atypical chest radiography appearances would be a diagnostic challenge for clinicians. In such presentations, both cardiogenic and non-cariogenic causes of pulmonary oedema should be considered.

Two in one: Overlapping CT findings of COVID-19 and underlying lung diseases

Coronavirus disease 2019 (COVID-19) is associated with pneumonia and has various pulmonary manifestations on computed tomography (CT). Although COVID-19 pneumonia is usually seen as bilateral predominantly peripheral ground-glass opacities with or without consolidation, it can present with atypical radiological findings and resemble the imaging findings of other lung diseases. Diagnosis of COVID-19 pneumonia is much more challenging for both clinicians and radiologists in the presence of pre-existing lung disease. The imaging features of COVID-19 and underlying lung disease can overlap and obscure the findings of each other. Knowledge of the radiological findings of both diseases and possible complications, correct diagnosis, and multidisciplinary consensus play key roles in the appropriate management of diseases. In this pictorial review, the chest CT findings are presented of patients with underlying lung diseases and overlapping COVID-19 pneumonia and the various reasons for radiological lung abnormalities in these patients are discussed.

Pulmonary Involvement in SARS-CoV-2 Infection Estimates Myocardial Injury Risk

Background and Objectives: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection represents a pathology with primary pulmonary involvement and multisystemic impact, including cardiovascular injuries. The present study aimed to assess the value of clinical, biochemical, and imaging factors in COVID-19 patients in determining the severity of myocardial involvement, and to create a model that can be used toevaluate myocardial injury risk based on clinical, biochemical and imaging factors. Materials and Methods: We performed an observational cohort study on 150 consecutive patients, evaluating their age, sex, hospitalization period, peripheral oxygen saturation (SpO₂) in ambient air, systolic and diastolic blood pressure, heart rate, respiratory rate, biochemical markers of cardiac dysfunction (TnI, and NT-proBNP), inflammatory markers (C reactive protein (CRP), fibrinogen, serum ferritin, interleukin-6 (IL-6), tumor necrosis factor alpha (TNFα)), D-dimers, lactate dehydrogenase (LDH), myoglobin and radio-imaging parameters. All patients underwent computerized tomography chest scan in the first two days following admission. Results: We observed elevated heart and respiratory rates, higher systolic blood pressure, and a lower diastolic blood pressure in the patients with cardiac injury; significant differences between groups were registered in TnI, NT-proBNP, LDH, CRP, and D-dimers. For the radiological parameters, we found proportional correlations with the myocardial injury for the severity of lung disease, number of pulmonary segments with alveolar consolidation, number of pulmonary lobes with pneumonia, crazy paving pattern, type of lung involvement, the extent of fibroatelectatic lesions and the mediastinal adenopathies. Conclusions: Myocardial injury occurred in 12% of patients in the study group. Ground glass opacities, interstitial interlobular septal thickening (crazy paving pattern), fibroatelectasic lesions and alveolar consolidations on CT scan were correlated with myocardial injury. Routine lung sectional imaging along with non-specific biomarkers (LDH, D-dimers, and CRP) can be further valuable in the characterization of the disease burden, thus impacting patient care.

Systemic Emergencies in COVID-19 Patient: A Pictorial Review

Since the first report of the outbreak in Wuhan, China in December 2019, as of 1 September 2021, the World Health Organization has confirmed more than 239 million cases of the novel coronavirus (SARS-CoV-2) infectious disease named coronavirus disease 2019 (COVID-19), with more than 4.5 million deaths. Although SARS-CoV-2 mainly involves the respiratory tract, it is considered to be a systemic disease. Imaging plays a pivotal role in the diagnosis of all manifestations of COVID-19 disease, as well as its related complications. The figure of the radiologist is fundamental in the management and treatment of the patient. The authors try to provide a systematic approach based on an imaging review of major multi-organ manifestations of this infection.

A Focused Review on Primary Graft Dysfunction after Clinical Lung Transplantation: A Multilevel Syndrome

Primary graft dysfunction (PGD) is the clinical syndrome of acute lung injury after lung transplantation (LTx). However, PGD is an umbrella term that encompasses the ongoing pathophysiological and -biological mechanisms occurring in the lung grafts. Therefore, we aim to provide a focused review on the clinical, physiological, radiological, histological and cellular level of PGD. PGD is graded based on hypoxemia and chest X-ray (CXR) infiltrates. High-grade PGD is associated with inferior outcome after LTx. Lung edema is the main characteristic of PGD and alters pulmonary compliance, gas exchange and circulation. A conventional CXR provides a rough estimate of lung edema, while a chest computed tomography (CT) results in a more in-depth analysis. Macroscopically, interstitial and alveolar edema can be distinguished below the visceral lung surface. On the histological level, PGD correlates to a pattern of diffuse alveolar damage (DAD). At the cellular level, ischemia-reperfusion injury (IRI) is the main trigger for the disruption of the endothelial-epithelial alveolar barrier and inflammatory cascade. The multilevel approach integrating all PGD-related aspects results in a better understanding of acute lung failure after LTx, providing novel insights for future therapies.

Acute Pulmonary Edema Due to Arteriovenous Shunt Placement after Lung Transplant

Lung transplant recipients are often complicated by immunosuppressant-induced nephropathy, which may require renal replacement therapy. We report a case of unilateral lung edema and pulmonary hypertension due to arteriovenous fistula placement in a patient with unilateral chronic lung allograft dysfunction after bilateral living-donor lobar lung transplantation. Lung transplant recipients with limited residual vascular beds, such as lobar graft or severe deviation in lung perfusion, are vulnerable to the acute increase in blood flow due to arteriovenous fistula placement and can easily develop pulmonary edema regardless of the left ventricular function. Hence, careful volume control is required.

[Increased pulmonary arterial and venous pressure]

BACKGROUND

Increases in pressure in the pulmonary arteries or pulmonary veins may be the result of a variety of underlying diseases. Noninvasive imaging plays a crucial role not only for identification, but also for differential diagnosis.

OBJECTIVES

This article provides a comparative review of the signs of increased pulmonary arterial and pulmonary venous pressure in chest X‑ray and computed tomography (CT).

RADIOLOGICAL PROCEDURES

Typical signs of a pulmonary arterial or pulmonary venous pressure increase in chest X‑ray and CT facilitate diagnosis of pulmonary hypertension (e.g., enlargement of central pulmonary arteries) and interstitial or alveolar pulmonary edema (e.g., Kerley lines/thickened interlobular septae or butterfly edema). A basic understanding of imaging findings and underlying pathophysiology helps in establishing the differential diagnosis.

CONCLUSIONS

Chest X‑ray and CT are essential for diagnosis of patients with suspected increased pulmonary arterial or pulmonary venous pressure.

Acute Respiratory Distress Syndrome: Focus on Viral Origin and Role of Pulmonary Lymphatics

Acute respiratory distress syndrome (ARDS) is a serious affection of the lung caused by a variety of pathologies. Great interest is currently focused on ARDS induced by viruses (pandemic influenza and corona viruses). The review describes pulmonary changes in ARDS and specific effects of the pandemic viruses in ARDS, and summarizes treatment options. Because the known pathogenic mechanisms cannot explain all aspects of the syndrome, the contribution of pulmonary lymphatics to the pathology is discussed. Organization and function of lymphatics in a healthy lung and in resorption of pulmonary edema are described. A future clinical trial may provide more insight into the role of hyaluronan in ARDS but the development of promising pharmacological treatments is unlikely because drugs play no important role in lymphedema therapy.