Diagnostic and therapeutic use of chest sonography: value in critically ill patients

COVID-19 Lung Ultrasound Scores and Lessons from the Pandemic: A Narrative Review

The WHO recently declared that COVID-19 no longer constitutes a public health emergency of international concern; however, lessons learned through the pandemic should not be left behind. Lung ultrasound was largely utilized as a diagnostic tool thanks to its feasibility, easy application, and the possibility to reduce the source of infection for health personnel. Lung ultrasound scores consist of grading systems used to guide diagnosis and medical decisions, owning a good prognostic value. In the emergency context of the pandemic, several lung ultrasound scores emerged either as new scores or as modifications of pre-existing ones. Our aim is to clarify the key aspects of lung ultrasound and lung ultrasound scores to standardize their clinical use in a non-pandemic context. The authors searched on PubMed for articles related to "COVID-19", "ultrasound", and "Score" until 5 May 2023; other keywords were "thoracic", "lung", "echography", and "diaphragm". A narrative summary of the results was made. Lung ultrasound scores are demonstrated to be an important tool for triage, prediction of severity, and aid in medical decisions. Ultimately, the existence of numerous scores leads to a lack of clarity, confusion, and an absence of standardization.

Bedside Chest Ultrasound in Postoperative Pediatric Cardiac Surgery Patients: Comparison With Bedside Chest Radiography

OBJECTIVE

The primary objective was to study the degree of agreement between the chest ultrasound (CUS) studies and chest x-ray (CXR) studies in postoperative pediatric cardiac surgical patients regarding the diagnosis of thoracic abnormalities, and also to compare the diagnostic performance of CUS in reference to CXR for the detection of thoracic abnormalities. The secondary objective was to compare the necessity for interventions done on the basis of CUS and CXR findings in the postoperative setting.

DESIGN

A prospective observational study.

SETTING

At a postoperative pediatric cardiac surgical intensive care unit in a tertiary-care center.

PARTICIPANTS

One hundred sixty patients between the age of 2 months to 18 years undergoing elective cardiac surgery for various congenital heart diseases.

INTERVENTIONS

After obtaining permission from the institutional ethics committee, 160 pediatric cardiac surgical patients were studied prospectively in the postoperative period. On the day of surgery (postoperative day [POD] 0), bedside CXR was done in the immediate postoperative period. After bedside CXR, CUS examination was performed and then interpreted by the principal investigator. The CXR was interpreted by the surgical team. Provisional diagnosis was made by the principal investigator and surgical team. Any intervention required was decided based on CXR or CUS findings or both. The procedure was repeated in the morning of POD 1.

MEASUREMENTS AND MAIN RESULTS

The degree of agreement between CUS studies and CXR studies in detecting abnormalities was evaluated by Cohen's kappa (k) statistics. The diagnostic performance of CUS was compared with that of CXR using sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy. Overall, kappa analysis (k) showed substantial agreement between the findings of the CUS and CXR studies (k = 0.749). The diagnostic performance of CUS, as compared with CXR, was found to have a sensitivity of 96.9%, specificity of 84.75%, PPV of 73.4%, NPV of 98.43%, and diagnostic accuracy of 88.44%. In 94 abnormal findings, the interventions were done based on CUS or CXR findings or both. Overall, there was a substantial agreement (k = 0.787) between CUS and CXR regarding the necessity for interventions.

CONCLUSIONS

The degree of agreement between CUS and CXR studies was substantial for atelectasis, interstitial edema, and diaphragmatic weakness. The degree of agreement between CUS and CXR studies was almost perfect for pneumothorax and fair for pleural effusion. More CUS studies detected intrathoracic pathologies than CXR studies. The CUS also detected abnormalities earlier than CXR and was found to be useful for the early institution of intervention therapy in patients with interstitial edema and atelectasis. It would be reasonable to conclude that CUS may be considered in some instances as an alternative to CXR.

The impact of lung ultrasound on clinical-decision making across departments: a systematic review

Background

Lung ultrasound has established itself as an accurate diagnostic tool in different clinical settings. However, its effects on clinical-decision making are insufficiently described. This systematic review aims to investigate the impact of lung ultrasound, exclusively or as part of an integrated thoracic ultrasound examination, on clinical-decision making in different departments, especially the emergency department (ED), intensive care unit (ICU), and general ward (GW).

Methods

This systematic review was registered at PROSPERO (CRD42021242977). PubMed, EMBASE, and Web of Science were searched for original studies reporting changes in clinical-decision making (e.g. diagnosis, management, or therapy) after using lung ultrasound. Inclusion criteria were a recorded change of management (in percentage of cases) and with a clinical presentation to the ED, ICU, or GW. Studies were excluded if examinations were beyond the scope of thoracic ultrasound or to guide procedures. Mean changes with range (%) in clinical-decision making were reported. Methodological data on lung ultrasound were also collected. Study quality was scored using the Newcastle–Ottawa scale.

Results

A total of 13 studies were included: five studies on the ED (546 patients), five studies on the ICU (504 patients), two studies on the GW (1150 patients), and one study across all three wards (41 patients). Lung ultrasound changed the diagnosis in mean 33% (15–44%) and 44% (34–58%) of patients in the ED and ICU, respectively. Lung ultrasound changed the management in mean 48% (20–80%), 42% (30–68%) and 48% (48–48%) of patients in the ED, in the ICU and in the GW, respectively. Changes in management were non-invasive in 92% and 51% of patients in the ED and ICU, respectively. Lung ultrasound methodology was heterogeneous across studies. Risk of bias was moderate to high in all studies.

Conclusions

Lung ultrasound, exclusively or as a part of thoracic ultrasound, has substantial impact on clinical-decision making by changing diagnosis and management in the EDs, ICUs, and GWs. The current evidence level and methodological heterogeneity underline the necessity for well-designed trials and standardization of methodology.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13089-021-00253-3.

Diagnostic Challenges in Sepsis

Purpose of Review

Sepsis is a leading cause of death worldwide. Groundbreaking international collaborative efforts have culminated in the widely accepted surviving sepsis guidelines, with iterative improvements in management strategies and definitions providing important advances in care for patients. Key to the diagnosis of sepsis is identification of infection, and whilst the diagnostic criteria for sepsis is now clear, the diagnosis of infection remains a challenge and there is often discordance between clinician assessments for infection.

Recent Findings

We review the utility of common biochemical, microbiological and radiological tools employed by clinicians to diagnose infection and explore the difficulty of making a diagnosis of infection in severe inflammatory states through illustrative case reports. Finally, we discuss some of the novel and emerging approaches in diagnosis of infection and sepsis.

Summary

While prompt diagnosis and treatment of sepsis is essential to improve outcomes in sepsis, there remains no single tool to reliably identify or exclude infection. This contributes to unnecessary antimicrobial use that is harmful to individuals and populations. There is therefore a pressing need for novel solutions. Machine learning approaches using multiple diagnostic and clinical inputs may offer a potential solution but as yet these approaches remain experimental.

Small Drainage Volumes of Pleural Effusions Are Associated with Complications in Critically Ill Patients: A Retrospective Analysis

Pleural effusions are a common finding in critically ill patients and small bore chest drains (SBCD) are proven to be efficient for pleural drainage. The data on the potential benefits and risks of drainage remains controversial. We aimed to determine the cut-off volume for complications, to investigate the impact of pleural drainage and drained volume on clinically relevant outcomes. Medical records of all critically ill patients undergoing insertion of SBCD were retrospectively examined. We screened 13,003 chest radiographs and included 396 SBCD cases in the final analysis. SBCD drained on average 900 mL, with less amount in patients with complications (p = 0.003). A drainage volume of 975 mL in 24 h represented the optimal threshold for complications. Pneumothorax was the most frequent complication (4.5%), followed by bleeding (0.8%). Female and lighter-weighted patients experienced a higher risk for any complication. We observed an improvement in the arterial partial pressure of oxygen and respiratory quotient (p < 0.001). We conclude that the small drainage volumes are associated with complications in critically ill patients—the more you drain, the safer the procedure gets. The use of SBCD is a safe and efficient procedure, further investigations regarding the higher rate of complications in female and lighter-weighted patients are desirable.

ERS statement on chest imaging in acute respiratory failure

Chest imaging in patients with acute respiratory failure plays an important role in diagnosing, monitoring and assessing the underlying disease. The available modalities range from plain chest X-ray to computed tomography, lung ultrasound, electrical impedance tomography and positron emission tomography. Surprisingly, there are presently no clear-cut recommendations for critical care physicians regarding indications for and limitations of these different techniques.The purpose of the present European Respiratory Society (ERS) statement is to provide physicians with a comprehensive clinical review of chest imaging techniques for the assessment of patients with acute respiratory failure, based on the scientific evidence as identified by systematic searches. For each of these imaging techniques, the panel evaluated the following items: possible indications, technical aspects, qualitative and quantitative analysis of lung morphology and the potential interplay with mechanical ventilation. A systematic search of the literature was performed from inception to September 2018. A first search provided 1833 references. After evaluating the full text and discussion among the committee, 135 references were used to prepare the current statement.These chest imaging techniques allow a better assessment and understanding of the pathogenesis and pathophysiology of patients with acute respiratory failure, but have different indications and can provide additional information to each other.

Thoracic ultrasonography: a narrative review

This narrative review focuses on thoracic ultrasonography (lung and pleural) with the aim of outlining its utility for the critical care clinician. The article summarizes the applications of thoracic ultrasonography for the evaluation and management of pneumothorax, pleural effusion, acute dyspnea, pulmonary edema, pulmonary embolism, pneumonia, interstitial processes, and the patient on mechanical ventilatory support. Mastery of lung and pleural ultrasonography allows the intensivist to rapidly diagnose and guide the management of a wide variety of disease processes that are common features of critical illness. Its ease of use, rapidity, repeatability, and reliability make thoracic ultrasonography the "go to" modality for imaging the lung and pleura in an efficient, cost effective, and safe manner, such that it can largely replace chest imaging in critical care practice. It is best used in conjunction with other components of critical care ultrasonography to yield a comprehensive evaluation of the critically ill patient at point of care.

Utility of pleural effusion drainage in the ICU: An updated systematic review and META-analysis

PURPOSE

The effects on the respiratory or hemodynamic function of drainage of pleural effusion on critically ill patients are not completely understood. First outcome was to evaluate the PiO₂/FiO₂ (P/F) ratio before and after pleural drainage.

SECONDARY OUTCOMES

evaluation of A-a gradient, End-Expiratory lung volume (EELV), heart rate (HR), mean arterial pressure (mAP), left ventricular end-diastolic volume (LVEDV), stroke volume (SV), cardiac output (CO), ejection fraction (EF), and E/A waves ratio (E/A). A tertiary outcome: evaluation of pneumothorax and hemothorax complications.

MATERIALS AND METHODS

Searches were performed on MEDLINE, EMBASE, COCHRANE LIBRARY, SCOPUS and WEB OF SCIENCE databases from inception to June 2018 (PROSPERO CRD42018105794).

RESULTS

We included 31 studies (2265 patients). Pleural drainage improved the P/F ratio (SMD: -0.668; CI: -0.947-0.389; p < .001), EELV (SMD: -0.615; CI: -1.102-0.219; p = .013), but not A-a gradient (SMD: 0.218; CI: -0.273-0.710; p = .384). HR, mAP, LVEDV, SV, CO, E/A and EF were not affected. The risks of pneumothorax (proportion: 0.008; CI: 0.002-0.014; p = .138) and hemothorax (proportion: 0.006; CI: 0.001-0.011; p = .962) were negligible.

CONCLUSIONS

Pleural effusion drainage improves oxygenation of critically ill patients. It is a safe procedure. Further studies are needed to assess the hemodynamic effects of pleural drainage.

Diagnostic Performance of 6-Point Lung Ultrasound in ICU Patients: A Comparison with Chest X-Ray and CT Thorax

Objective

To evaluate the diagnostic performance of a rapid bedside 6-point lung ultrasonography (LUS) performed by an intensive care unit (ICU) physician for detection of four common pathological conditions of the lung, such as alveolar consolidation, pleural effusion, interstitial syndrome and pneumothorax, in critically ill patients and its comparison with bedside chest X-ray (CXR) and high-resolution computed tomography (CT) scan of the thorax. Volume of pleural effusion measured by LUS and CT thorax was also compared.

Methods

This was a cross-sectional, observational study of 90 adult patients with an acute lung injury score of ≥1 admitted to the medical-surgical ICU. They were examined by CXR and 6-point LUS as per BLUE protocol at bedside, followed by CT thorax in the radiology department.

Results

The sensitivity of 6-point LUS for detecting alveolar consolidation, pleural effusion, interstitial syndrome and pneumothorax was 76%, 88%, 83% and 89%, respectively, which was remarkably higher than that of CXR. The specificity of LUS was 100% for all pathologies, which was again notably higher than that of CXR except for interstitial syndrome for which it was 88.5%. Measurement of volume of pleural effusion by LUS was comparable and had a strong absolute agreement with CT thorax.

Conclusion

6-Point LUS can be a useful diagnostic tool and is better than CXR in diagnosing respiratory pathologies in critically ill patients. Owing to the comparable diagnostic performance of LUS and CT scan and with increasing evidence in favour of LUS, the requirement of CT thorax can be reduced. Radiation hazards associated with CXR and CT, as well as potentially risky transfer of patients to CT room, can also be minimised.

Cardiothoracic MRI in the ICU: A 10-Year Experience

RATIONALE AND OBJECTIVE

The objective of this study was to identify the feasibility and pitfalls of cardiothoracic magnetic resonance imaging (MRI) in intensive care unit (ICU) patients.

MATERIALS AND METHODS

This retrospective study identified adult ICU patients scheduled for cardiothoracic MRIs during a 10-year study period. ICU patients scheduled for brain MRIs served as a comparison group. A chart review was performed to identify factors impacting a patient's ability to undergo an MRI. Differences between completed and canceled examinations for both cardiothoracic and brain MRIs were evaluated. For the cardiothoracic group, clinical indications and the diagnostic value of the study performed were also identified.

RESULTS

A total of 143 cardiothoracic MRIs and 1011 brain MRIs were requested. Cardiothoracic MRI patients were less frequently completed (52% vs 62%), more frequently men (64% vs 43%), younger (55 vs 63 years), less likely mechanically ventilated (8% vs 29%), more likely to require intravenous contrast (83% vs 23%), and had longer examination times compared to brain MRI patients (64 vs 21 minutes). Successful completion of cardiothoracic MRI was associated with lower serum creatinine, higher glomerular filtration rate, and the absence of mechanical ventilation; significant differences were not seen with regard to gender and use of vasoactive agents. Cardiothoracic MRI results were diagnostic in 69% of examinations, most frequently when performed for myocardial disease (84%) and aortic disease (33%), and less frequently for viability (33%).

CONCLUSIONS

In an ICU population, successful completion of cardiothoracic MRI is challenging but feasible in patients with intact renal function and the absence of mechanical ventilation. Examinations were most frequently diagnostic for myocardial and aortic disease indications.

Lung Ultrasound and Blood Gas-Based Classification of Critically Ill Patients with Dyspnea: A Pathophysiologic Approach

Introduction:

The objective of this study was to classify dyspneic patients and to evaluate outcome variables on the basis of lung ultrasound (LUS) and arterial blood gas (ABG) findings.

Methods:

We performed a retrospective chart-based review in which we included patients with dyspnea admitted to our intensive care unit (ICU) between March 2015 and August 2016. On the basis of LUS (presence of A-lines/B-lines) and ABG (hypoxia/hypercarbia), patients were classified into six groups: (i) metabolic defect (dry lung, no hypoxia); (ii) perfusion defect (dry lung, hypoxia); (iii) ventilation defect (dry lung, hypoxia, and hypercarbia); (iv) ventilation and alveolar defect (wet lung, hypoxia, and hypercarbia); (v) alveolar defect-consolidation ([wet lung] hypoxia, no echocardiographic [ECG] abnormality); (vi) alveolar defect-pulmonary edema (wet lung [usually bilateral], hypoxia, ECG abnormality). The patient's demographic data, sequential organ failure assessment (SOFA) score, need for intubation, vasopressors, form of mechanical ventilation, ICU outcome, and length of stay were noted.

Results:

A total of 244 out of 435 patients were eligible for inclusion in the study. The median age was 56 years. 132 patients (54.1%) required mechanical ventilation, and median SOFA score was 7. Noninvasive ventilation was required in 87.5% of patients with ventilation defect as compared to 9.2% with alveolar defect-consolidation (P < 0.0001). We had 21.7% mortality in patients with alveolar defect-consolidation, 10.8% mortality in patients with metabolic defect, and 8.7% mortality in patients with alveolar defect-pulmonary edema (P < 0.0001).

Conclusion:

This classification gives an organized approach in managing patients with dyspnea. It predicts that patients with alveolar defect-consolidation are most sick of all the groups and need immediate intervention.

Systematic review and meta-analysis for the use of ultrasound versus radiology in diagnosing of pneumonia

Background

Physicians are increasingly using point of care lung ultrasound (LUS) for diagnosing pneumonia, especially in critical situations as it represents relatively easy and immediately available tool. They also used it in many associated pathological conditions such as consolidation, pleural effusion, and interstitial syndrome with some reports of more accuracy than chest X-ray. This systematic review and meta-analysis are aimed to estimate the pooled diagnostic accuracy of ultrasound for the diagnosis of pneumonia versus the standard chest radiological imaging.

Methods and main results

A systematic literature search was conducted for all published studies comparing the diagnostic accuracy of LUS against a reference Chest radiological exam (C X-ray or Chest computed Tomography CT scan), combined with clinical criteria for pneumonia in all age groups. Eligible studies were required to have a Chest X-ray and/or CT scan at the time of clinical evaluation. The authors extracted qualitative and quantitative information from eligible studies, and calculated pooled sensitivity and specificity and pooled positive/negative likelihood ratios (LR). Twenty studies containing 2513 subjects were included in this meta-analysis. The pooled estimates for lung ultrasound in the diagnosis of pneumonia were, respectively, as follows: Overall pooled sensitivity and specificity for diagnosis of pneumonia by lung ultrasound were 0.85 (0.84–0.87) and 0.93 (0.92–0.95), respectively. Overall pooled positive and negative LRs were 11.05 (3.76–32.50) and 0.08 (0.04–0.15), pooled diagnostic Odds ratio was 173.64 (38.79–777.35), and area under the pooled ROC (AUC for SROC) was 0.978.

Conclusion

Point of care lung ultrasound is an accurate tool for the diagnosis of pneumonia. Considering being easy, readily availability, low cost, and free from radiological hazards, it can be considered as important diagnostic strategy in this condition.

Safety and Value of Thoracentesis in Medical ICU Patients

The objective of this study was to determine the safety and value of thoracentesis in an ICU, Thoracentesis is a safe procedure for critically ill patients, even those on mechanical ventilators, and usually confirms the suspected diagnosis. However, thoracentesis revealed an unexpected diagnosis that changed management in 12% of patients. Repeat or contralateral thoracentesis is indicated when either the clinical course is inconsistent or may represent a complication of the original diagnosis.

Role of the Interventional Pulmonologist in the Intensive Care Unit

Interventional pulmonology is a new field within the pulmonary and critical care medicine specialty with a focus on invasive diagnostic and therapeutic modalities in airway and pleural disorders. The interventional pulmonologist is highly qualified to take a prominent role in the intensive care unit in a consultative fashion to provide assistance with pleural procedures, establishment and care of artificial airways, and management of patients with respiratory failure attributable to structural central airway disorders. The presence of a dedicated operator with advanced skills facilitates access to specialized procedures in an expeditious and safe manner. Clear communication between the interventional pulmonologist and intensivist is vital to ensure a collaborative effort that delivers optimal patient care.

The past, current and future of diagnosis and management of pleural disease

Pleural disease is frequently encountered by the chest physician. Pleural effusions arise as the sequelae of underlying disease processes including pressure/volume imbalances, infection and malignancy. In addition to pleural effusions, persistent air leaks after surgery and bronchopleural fistulae remain a challenge. Our understanding of pleural disease including its diagnosis and management, have made tremendous strides. The introduction of the molecular detection of organism specific infection, risk stratification and improvements in the non-surgical treatment of patients with pleural infection are all within reach and may be the standard of care in the very near future. Malignant pleural effusion management continues to evolve with the introduction of tunneled pleural catheters and procedures combining that and chemical pleurodesis. These advances in the diagnostic and therapeutic evaluation of pleural disease as well as what seems to be an increasing multidisciplinary interest in the space foretell a bright future.

Extension of the Thoracic Spine Sign: A New Sonographic Marker of Pleural Effusion

OBJECTIVES

Dyspnea is a common emergency department (ED) condition, which may be caused by pleural effusion and other thoracic diseases. We present data on a new sonographic marker, the extension of the thoracic spine sign, for diagnosis of pleural effusion.

METHODS

In this prospective study, we enrolled a convenience sample of undifferentiated patients who underwent computed tomography (CT) of the abdomen or chest, which was performed as part of their emergency department evaluations. Patients underwent chest sonography to assess the utility of the extension of the thoracic spine sign for diagnosing pleural effusion. The point-of-care sonographic examinations were performed and interpreted by emergency physicians who were blinded to information in the medical records. Sonographic results were compared to radiologists' interpretations of the CT results, which were considered the criterion standard.

RESULTS

Forty-one patients were enrolled, accounting for 82 hemithoraces. Seven hemithoraces were excluded from the analysis due to various limitations, leaving 75 hemithoraces for the final analysis. The median time for completion of the sonographic examination was 3 minutes. The sensitivity and specificity for extension of the thoracic spine were 73.7% (95% confidence interval [CI], 48.6%-89.9%) and 92.9% (95%CI, 81.9%-97.7%), respectively. Overall, there were 5 hemithoraces with false-negative results when using the extension sign. Of those 5 cases, 4 were found to have trace pleural effusions on CT. When trace pleural effusions were excluded in a subgroup analysis, the sensitivity and specificity of extension of the thoracic spine were 92.9% (95% CI, 64.2%-99.6%) and 92.9% (95% CI, 81.9%-97.7%).

CONCLUSIONS

We found the extension of the thoracic spine sign to be an excellent diagnostic tool for clinically relevant pleural effusion.

Potential role of ultrasound in anesthesia and intensive care

One of the most exiting recent technological advances in the field of anesthesia to track the region of interest is the introduction of anatomical evaluation by ultrasound imaging. Widespread use of this modality depends on its proven clinical efficacy, cost effectiveness, and practicality as it allows anesthesiologist to evaluate complex and varied anatomy prior to needle insertion. Sound used in medicine is not significantly transmitted by air or bone but through fluids which make up the larger part of soft tissues in the body. Ultrasound has been shown to offer excellent guidance for difficult venous access, epidural space identification in cases of difficult anatomy, delineating nerve plexuses for chronic nerve blocks, for regional anesthesia, and in transesophageal echocardiography for cardiac imaging with blood flows or in an otherwise high-risk patient where interventional procedure is required. It has special application to assess the narrowest diameter of the subglottic upper airway. A systemic literature search was performed in PubMed and the Cochrane library. The search strategy was set up using either single text word or combinations. We also included the studies where in these techniques were compared with conventional methods . Despite the initial excitement of this technique, ultrasound visualization is still indirect and images are subject to individual interpretation. It is gradually becoming routine in daily practice at our institution due to its reliability and safety. Though ultrasound is much safer, exposure in terms of intensity and time should be limited as far as possible, as high-energy ultrasound can cause heating and damage to tissues. In this review, we discuss established and future areas of ultrasound imaging and emphasize the use of B-mode ultrasound to improve the efficacy of interventional techniques. We have also illustrated potential uses with reference to cross-sectional B-mode images which visually represent a slice of tissues and are the easiest images for interpretation by clinicians.

Transthoracic ultrasound in the assessment of pleural and pulmonary diseases: use and limitations

Interest in transthoracic ultrasound (US) procedures increased after the availability of portable US equipment suitable for use at the patient's bedside. It is possible to detect space-occupying lesions of the pleura, pleural effusion, focal or diffuse pleural thickening and subpleural lesions of the lung, even in emergency settings. Transthoracic US is useful as a guidance system for thoracentesis and peripheral lesion biopsy, where it minimises the occurrence of pneumothorax and haemorrhage. Transthoracic US imaging is strongly influenced by physical interaction of the ultrasonic beam at the tissue/air interface, which gives rise to reverberations classified as simple (A-line), "comet tail" and "ring down"(B-line) artifacts. Although these artifacts can be suggestive of a disease condition, they are essentially imaging errors present even in normal subjects and in empty-pleura post-pneumonectomy patients. In order to clarify some confusion and to report on the state of the art, we present a review of the literature on transthoracic US in diseases of the pleura and peripheral lung regions and our own clinical experience over 3 decades. The review focuses on quality assurance procedures and their value in diagnostic imaging and patient monitoring and warns against possible inappropriate indications and misleading information. Thoracic US is much more than "fishing for the moon in the well".

Pleural effusions on the intensive care unit; hidden morbidity with therapeutic potential

Despite 50-60% of intensive care patients demonstrating evidence of pleural effusions, there has been little emphasis placed on the role of effusions in the aetiology of weaning failure. Critical illness and mechanical ventilation lead to multiple perturbations of the normal physiological processes regulating pleural fluid homeostasis, and consequently, failure of normal pleural function occurs. Effusions can lead to deleterious effects on respiratory mechanics and gas exchange, and when extensive, may lead to haemodynamic compromise. The widespread availability of bedside ultrasound has not only facilitated earlier detection of pleural effusions but also safer fluid sampling and drainage. In the majority of patients, pleural drainage leads to improvements in lung function, with data from spontaneously breathing individuals demonstrating a consistent symptomatic improvement, while a meta-analysis in critically ill patients shows an improvement in oxygenation. The effects on respiratory mechanics are less clear, possibly reflecting heterogeneity of underlying pathology. Limited data on clinical outcome from pleural fluid drainage exist; however, it appears to be a safe procedure with a low risk of major complications. The current level of evidence would support a clinical trial to determine whether the systematic detection and drainage of pleural effusions improve clinical outcomes.

El uso de las imágenes en el trauma de tórax

El  trauma  de  tórax  produce  un  desenlace  fatal  en aproximadamente un 25% de los traumatismos en general. Constituye  la  principal  causa  de  morbilidad  y  mortalidad después  del  trauma  craneoencefálico  y  las  lesiones  de  la médula ósea; puede afectar cualquiera o la totalidad de las estructuras del  tórax, desde los tejidos blandos, la pleura, los pulmones y el diafragma hasta las estructuras mediastinales incluyendo el corazón. Constituye una urgencia médica que requiere de un rápido y oportuno manejo. Su diagnóstico temprano  y  un  adecuado  tratamiento  en  los  servicios  de urgencias  evitarán  una  resolución  fatal  en  la  mayoría  de pacientes  que  ha  sufrido  un  trauma  de  tórax  teniendo  en cuenta que aproximadamente solo de un 10 a 15 % requiere manejo  quirúrgico.  Es  de  vital  importancia  establecer  un diagnóstico, por  lo cual  las  imágenes diagnósticas, entre ellas la  radiografía  convencional  y  la  tomografía  computarizada multidetector juegan un papel fundamental ya que cada vez se están  utilizando  con  mayor  frecuencia  porque  brindan información rápida y precisa en  la variedad de  lesiones de  los pacientes que han sufrido trauma; además las imágenes de tomografía  computada  multiplanar  y  volumétricas proporcionan una mejor visualización de las lesiones con un aumento en la comprensión de estas para así poder ofrecer un tratamiento a  las  lesiones  secundarias a un  trauma de tórax. Por  lo  tanto, el profesional de  la medicina debe  tener un conocimiento claro acerca de la ayuda diagnóstica de mejor elección y de  la  interpretación de  la misma. Para la realización del presente artículo se hizo una búsqueda sistemática de la literatura en relación al trauma de tórax, su epidemiología, fisiopatología,  clasificación  y  los  métodos  de  ayudas diagnósticas por  imagen que se utilizan para su adecuado diagnóstico y manejo. 

Ultrasound for the Detection of Pleural Effusions and Guidance of the Thoracentesis Procedure

Objective. To review the use of ultrasound for the detection of pleural effusions and guidance of the thoracentesis procedure. Methods. Two clinical cases will be presented in which ultrasound proved beneficial in guiding the diagnosis and management of patients with pleural effusions and respiratory distress. The ultrasound techniques for the evaluation of pleural effusions and performance of the thoracentesis procedure are discussed. A review of the most current literature follows to present the known diagnostic and safety benefits of ultrasound guidance for thoracentesis. Conclusions. Ultrasound improves the diagnostic accuracy for the detection of pleural effusions over standard chest radiographs. Ultrasound can also diagnose a complicated pleural effusion that may be at higher risk for an adverse outcome during a thoracentesis. Optimally, thoracentesis should be performed under direct ultrasound guidance to decrease the complication rate and improve patient safety.

Utility of draining pleural effusions in mechanically ventilated patients

PURPOSE OF REVIEW

Pleural effusions are prevalent in mechanically ventilated patients, and clinicians frequently consider draining the effusions. It is controversial whether patients benefit from pleural drainage in terms of either physiological or clinical outcomes.

RECENT FINDINGS

Pleural drainage may be undertaken for a variety of reasons. Effusions are an important potential source of infection in patients with undifferentiated sepsis. Pleural drainage may improve hypoxemia or lung mechanics, but the physiological response depends on a complex interplay between lung and chest wall compliance, applied positive end-expiratory pressure and drainage volume. Pleural effusions may be associated with significant cyclic lung recruitment and collapse during tidal ventilation. Because effusions are primarily accommodated by descent of the diaphragm, they can also impair diaphragm mechanics significantly. There is very limited data in the literature to support the use of pleural drainage to accelerate liberation from mechanical ventilation, and there are no randomized controlled trials published to date.

SUMMARY

Pleural drainage may benefit certain patient populations based on individual physiological considerations, but randomized controlled trials evaluating the impact on weaning outcomes are lacking. Future research efforts should focus on identifying patient populations most likely to benefit and clarify the mechanisms by which weaning may be accelerated after pleural drainage.

Prospective trial evaluating sonography after thoracic surgery in postoperative care and decision making

OBJECTIVE

Following thoracic surgery, daily chest X-rays (CXRs) are performed to assess patient evolution and to make decisions regarding chest tube removal and patient discharge. Sonography after thoracic surgery (SATS) has the potential to be an effective, convenient, inexpensive and easy to learn tool in the post-operative management of thoracic surgery patients. We hypothesized that SATS could alleviate the need for repetitive CXRs, thus reducing the related risks, costs and inconvenience.

METHODS

This study consisted of a prospective cohort trial. All patients scheduled to undergo thoracic surgery at a single academic medical centre were eligible. Post-operative bedside pleural ultrasound was performed whenever a CXR was ordered by the treating team. Investigators specifically assessed patients with the goals of identifying pleural effusions and pneumothoraces. Study investigators were blinded to CXR results. SATS findings were compared with CXRs, which were considered the gold standard in routine post-operative pleural space evaluation.

RESULTS

One hundred and twenty patients were prospectively enrolled over a 5.5-month period. Three hundred and fifty-two ultrasound examinations were performed (mean = 3.0 ± 2.4 exams per patient). The time interval between the ultrasound and the comparative CXR was 166 ± 149 min. The mean time required to perform SATS was 11 ± 6 min per exam. In the detection of pleural effusion, SATS yielded a sensitivity of 83.1% and a specificity of 59.3%. In the detection of pneumothoraces, a sensitivity of 21.2% and a specificity of 94.7% were obtained.

CONCLUSIONS

Post-operative ultrasound may alleviate the need to perform routine CXR in patients with a previously ruled out pneumothorax. SATS used selectively may be able to reduce the number of routine CXRs performed; however, it does not have high enough accuracy to replace CXRs.

Lung ultrasound in critically ill patients: comparison with bedside chest radiography

PURPOSE

To compare the diagnostic performance of lung ultrasound and bedside chest radiography (CXR) for the detection of various pathologic abnormalities in unselected critically ill patients, using thoracic computed tomography (CT) as a gold standard.

METHODS

Forty-two mechanically ventilated patients scheduled for CT were prospectively studied with a modified lung ultrasound protocol. Four pathologic entities were evaluated: consolidation, interstitial syndrome, pneumothorax, and pleural effusion. Each hemithorax was evaluated for the presence or absence of each abnormality.

RESULTS

Eighty-four hemithoraces were evaluated by the three imaging techniques. The sensitivity, specificity, and diagnostic accuracy of CXR were 38, 89, and 49% for consolidation, 46, 80, and 58% for interstitial syndrome, 0, 99, and 89% for pneumothorax, and 65, 81, and 69% for pleural effusion, respectively. The corresponding values for lung ultrasound were 100, 78, and 95% for consolidation, 94, 93, and 94% for interstitial syndrome, 75, 93, and 92% for pneumothorax, and 100, 100, and 100% for pleural effusion, respectively. The relatively low sensitivity of lung ultrasound for pneumothorax could be due to small number of cases (n = 8) and/or suboptimal methodology.

CONCLUSIONS

In our unselected general ICU population lung ultrasound has a considerably better diagnostic performance than CXR for the diagnosis of common pathologic conditions and may be used as an alternative to thoracic CT.

Utility and safety of draining pleural effusions in mechanically ventilated patients: a systematic review and meta-analysis

INTRODUCTION

Pleural effusions are frequently drained in mechanically ventilated patients but the benefits and risks of this procedure are not well established.

METHODS

We performed a literature search of multiple databases (MEDLINE, EMBASE, HEALTHSTAR, CINAHL) up to April 2010 to identify studies reporting clinical or physiological outcomes of mechanically ventilated critically ill patients who underwent drainage of pleural effusions. Studies were adjudicated for inclusion independently and in duplicate. Data on duration of ventilation and other clinical outcomes, oxygenation and lung mechanics, and adverse events were abstracted in duplicate independently.

RESULTS

Nineteen observational studies (N = 1,124) met selection criteria. The mean PaO2:FiO2 ratio improved by 18% (95% confidence interval (CI) 5% to 33%, I2 = 53.7%, five studies including 118 patients) after effusion drainage. Reported complication rates were low for pneumothorax (20 events in 14 studies including 965 patients; pooled mean 3.4%, 95% CI 1.7 to 6.5%, I2 = 52.5%) and hemothorax (4 events in 10 studies including 721 patients; pooled mean 1.6%, 95% CI 0.8 to 3.3%, I2 = 0%). The use of ultrasound guidance (either real-time or for site marking) was not associated with a statistically significant reduction in the risk of pneumothorax (OR = 0.32; 95% CI 0.08 to 1.19). Studies did not report duration of ventilation, length of stay in the intensive care unit or hospital, or mortality.

CONCLUSIONS

Drainage of pleural effusions in mechanically ventilated patients appears to improve oxygenation and is safe. We found no data to either support or refute claims of beneficial effects on clinically important outcomes such as duration of ventilation or length of stay.

Bildgebende Verfahren: Röntgen, Ultraschall, CT, Nuklearmedizin

In der Intensivmedizin findet die radiologische Diagnostik überwiegend am Krankenbett statt (»bedside radiology«). Etwa 90 % der radiologischen Untersuchungen in der Intensiv- und Notfallmedizin stellen projektionsradiographische Röntgenaufnahmen des Thorax, des Abdomens und des Skelettsystems dar. In zunehmendem Maße werden neben den klassischen Aufnahmen auch die Schnittbildverfahren eingesetzt. Hier kommt der Ultraschalldiagnostik eine führende Rolle zu, gefolgt von der Computertomographie (CT).

Can chest ultrasonography replace standard chest radiography for evaluation of acute dyspnea in the ED?

BACKGROUND

We examined the concordance between chest ultrasonography and chest radiography in patients with dyspnea, using chest CT scanning as the gold standard in case of mismatch between the two modalities.

METHODS

A prospective, blinded, observational study was conducted in the ED of a university-affiliated teaching hospital. All consecutive patients presenting for dyspnea during a single emergency physician shift were enrolled independently from the underlying disease. Only patients with trauma were excluded.

RESULTS

Both ultrasonography and radiography were performed in 404 patients; CT scanning was performed in 118 patients. Ultrasound interpretation was completed during the scan, whereas the average time between radiograph request and its final interpretation was 1 h and 35 min. Ultrasonography and radiography exhibited high concordance in most pulmonary diseases, especially in pulmonary edema (κ = 95%). For lung abnormalities such as free pleural effusion, loculated pleural effusion, pneumothorax, and lung consolidation, the concordance was similar for both left- and right-side lungs (all P not significant). When ultrasound scans and radiographs gave discordant results, CT scans confirmed the ultrasound findings in 63% of patients (P < .0001). Particularly, ultrasonography exhibited greater sensitivity than radiography in patients with free pleural effusion (P < .0001).

CONCLUSIONS

When performed by one highly trained physician, our study demonstrated high concordance between ultrasonography and radiography. When ultrasound scans and radiographs disagreed, ultrasonography proved to be more accurate in distinguishing free pleural effusion. Thus, considering the short time needed to have a final ultrasound report, this technique could become the routine imaging modality for patients with dyspnea presenting to the ED.

[Utility of the lung ultrasound in the intensive medicine unit]

The radiological diagnostic approach of the thorax in the critically ill patient has traditionally been based on the anteroposterior chest X-ray. However, it is generally accepted that it has important limitations regarding its diagnostic accuracy of pleuro-pulmonary disease. The introduction of computed tomography largely solved this problem, but with the dual disadvantage of a larger radiation dose and the unavoidable transportation outside of the ICU. In this context, the lung ultrasound has become an alternative technique, with the advantage that due to its portability, it is done at the patient's bedside. In the lung ultrasound, the ribs, spine and air in the thorax act as barriers to the ultrasounds, causing artifacts that must be recognized and interpreted for a correct diagnosis. However, intrathoracic diseases, existence of fluid in the pleural space and consolidation, or atelectasis in the lung provide a sufficient ultrasound window for the correct evaluation. In this review, we explain the lung and pleural ultrasound technique, define the normal pattern and the artifacts that serve to detect the abnormalities and we explain the criteria for the main diseases (consolidation, pleural effusion, pulmonary edema and pneumothorax). We also discuss the possible utility and limitations of the lung ultrasound in our daily practice, such as diagnosis of acute respiratory failure, detection, quantification and drainage of a pleural effusion, chest trauma, management and complications of acute respiratory distress syndrome and tracheal intubation success or failure.

Diagnostic accuracy of sonography for pleural effusion: systematic review

CONTEXT AND OBJECTIVE

The initial method for evaluating the presence of pleural effusion was chest radiography. Isolated studies have shown that sonography has greater accuracy than radiography for this diagnosis; however, no systematic reviews on this matter are available in the literature. Thus, the aim of this study was to evaluate the accuracy of sonography in detecting pleural effusion, by means of a systematic review of the literature.

DESIGN AND SETTING

This was a systematic review with meta-analysis on accuracy studies. This study was conducted in the Department of Diagnostic Imaging and in the Brazilian Cochrane Center, Discipline of Emergency Medicine and Evidence-Based Medicine, Department of Medicine, Universidade Federal de São Paulo (Unifesp), São Paulo, Brazil.

METHOD

The following databases were searched: Cochrane Library, Medline, Web of Science, Embase and Literatura Latino-Americana e do Caribe em Ciências da Saúde (Lilacs). The references of relevant studies were also screened for additional citations of interest. Studies in which the accuracy of sonography for detecting pleural effusion was tested, with an acceptable reference standard (computed tomography or thoracic drainage), were included.

RESULTS

Four studies were included. All of them showed that sonography had high sensitivity, specificity and accuracy for detecting pleural effusions. The mean sensitivity was 93% (95% confidence interval, CI: 89% to 96%), and specificity was 96% (95% CI: 95% to 98%).

CONCLUSIONS

In different populations and clinical settings, sonography showed consistently high sensitivity, specificity and accuracy for detecting fluid in the pleural space.

Role of thoracic ultrasound in the assessment of pleural and pulmonary diseases

Although numerous studies have been conducted on the use of ultrasonography (US) for the examination of thoracic structures, this procedure is not as widely accepted as abdominal US. The newer portable scanners can be used at the bedside to detect pleural malignancies and effusions, as well as peripheral lung nodules of the lung, even in seriously ill patients. Focal thickening of the pleura can be easily detected with US and further investigated with a US-guided biopsy. US guidance can also be used during percutaneous drainage of pleural effusion or transthoracic biopsy of peripheral lung lesions, thus reducing the incidence of procedure-related pneumothorax to almost zero. We review the current literature on thoracic US and present our clinical experience with the technique in large groups of patients with pleural and peripheral lung diseases.

Dynamic flow US, color Doppler US, and power Doppler US in the assessment of vessel signals of thoracic lesions abutting pulsatile organs

RATIONALE AND OBJECTIVES

Dynamic flow ultrasound (DFUS) is a new color Doppler imaging method with better B-mode imaging and fewer blooming effects and color noises. This study was designed to compare the imaging quality of vessel signals in thoracic lesions using DFUS, color Doppler US (CDUS), and power Doppler US (PDUS).

MATERIALS AND METHODS

Thirty-four patients with thoracic lesions abutting pulsatile organs [heart (n = 13), aorta (n = 14) and pulmonary artery (n = 7)] and undergoing complete chest US examinations were included to assess the imaging quality about vessel signals, blooming effect, color noise, and the influence of decision in needle biopsy between different US modes.

RESULTS

Our results showed that DFUS, CDUS, and PDUS could all demonstrate the vessel signals clearly (all P > .05). However, when focusing on the blooming effect and color noise, DFUS showed the more superior imaging quality than CDUS and PDUS (all P < or = .001); and acceptable blooming effects/color noise were found with 100% (34/34)/97% (33/34), 35% (12/34)/68% (23/34), and 26% (9/34)/38% (13/34) in DFUS, CDUS, and PDUS, respectively. Especially, in the assessment of decision making for percutaneous needle biopsy, DFUS had the less influence than CDUS and PDUS (3% [1/33] versus 29% [10/34] and 3% [1/33] versus 38% [13/34], both P < .01).

CONCLUSIONS

We concluded that DFUS has a clearly more superior imaging quality than CDUS and PDUS in demonstrating the vessel signals of thoracic lesions, with less blooming effect and color noise.

The evolving role of interventional pulmonary in the interdisciplinary approach to the staging and management of lung cancer. Part III: diagnosis and management of malignant pleural effusions

The diagnosis and management of a malignant pleural effusion can be one of the most vexing problems faced by physicians and their patients. Lung cancer is the most common primary tumor of origin with a prognosis that is limited, but variable and correlated with performance status (PS). Therefore, with a poor PS and known advanced lung cancer, establishing whether or not an effusion is malignant might not be necessary. Conversely, identifiable subsets of patients will have a much better survival, and establishing a definitive diagnosis could be of critical importance. In the great majority of cases, a diagnosis can be determined by serial thoracenteses with or without closed pleural biopsy. However, thoracoscopy is increasingly being utilized and can expedite the workup by obviating the need for repeated thoracenteses and/or closed pleural biopsy, while in the same setting providing definitive palliative treatment. Although studies comparing diagnostic and treatment strategies are limited, we will present the available data with the intention of providing the practicing oncologist with a practical strategy for the diagnosis and management of malignant pleural effusions due to lung cancer. The interventional pulmonologist can play an important role from diagnosis to palliation, greatly facilitating the care of patients with malignant pleural effusions.

Clinical review: Bedside lung ultrasound in critical care practice

Lung ultrasound can be routinely performed at the bedside by intensive care unit physicians and may provide accurate information on lung status with diagnostic and therapeutic relevance. This article reviews the performance of bedside lung ultrasound for diagnosing pleural effusion, pneumothorax, alveolar-interstitial syndrome, lung consolidation, pulmonary abscess and lung recruitment/derecruitment in critically ill patients with acute lung injury.

Diagnostic studies in patients with acute respiratory distress syndrome

Acute respiratory distress syndrome (ARDS) is a clinical-radiological diagnosis. Clinical diagnosis comprises severe hypoxemia assessed by arterial oxygen tension/fraction of inspired oxygen ratio of less than 200 and bilateral infiltrate on a chest radiograph in the absence of left atrial hypertension. The sensitivity and specificity of the clinical diagnosis vary based on the underlying etiology for ARDS. Except for presence of bilateral infiltrate on chest radiograph and severe hypoxemia on arterial blood gas, most diagnostic studies are used to exclude mimics of ARDS and potentially modify treatment. Computerized tomography of the chest is helpful in understanding the extent of the disease and is more sensitive in identifying pneumomediastinum and pneumothoraces seen frequently in patients with ARDS, which can be missed on a chest radiograph, especially if they are small in size. Measurements of alveolar dead space ventilation fraction can be helpful in determining the prognosis in individuals with ARDS. Bronchoalveolar lavage, transbronchial lung biopsy, and open lung biopsies can be safely performed in patients with ARDS. Bronchoalveolar lavage fluid in patients with ARDS shows neutrophil predominance with increased edema fluid to serum protein ratio. Diffuse alveolar damage, a pathognomic of ARDS, is seen on histopathology on transbronchial lung biopsy or open lung biopsy. Most common complications of these procedures include transient hypoxemia, respiratory acidosis, and pneumothorax with occasional persistent air leak. The potential risk of diagnostic studies should be balanced against the possible foreseeable benefits of the diagnostic studies.

Transthoracic ultrasound approach of thoracic aorta in critically ill patients with lung consolidation

PURPOSE

Normally, the aortic arch and the descending aorta are not visible using transthoracic ultrasonography. We hypothesize that lung consolidation of upper and lower lobes, by opening an acoustic window, may allow the ultrasound examination of the thoracic aorta.

METHODS

During a 2-month period, 18 consecutive patients hospitalized in the intensive care unit with consolidation of upper and/or lower lobes diagnosed by lung ultrasound were studied. The ascending and descending aorta and the aortic arch were systematically searched for by positioning the probe on the anterior, lateral, and posterior regions of the chest wall.

RESULTS

Among the 16 patients with left lower lobe consolidation, the descending aorta was always visible by positioning the probe on lateral and posterior parts of the chest wall. In the 4 patients with consolidation of the left upper lobe, the aortic arch was visible when positioning the probe on anterior and upper parts of the left chest wall. In the patient with right upper lobe consolidation, both the ascending aorta and the aortic arch were visible when positioning the probe on anterior and upper parts of the right chest wall.

CONCLUSIONS

In critically ill patients, the presence of consolidated upper and left lower lobes may allow the ultrasound examination of the different parts of the thoracic aorta.

Pleural Ultrasonography

Ultrasonography has achieved acceptance as a routine clinical tool for clinicians managing pleural disease. This article provides an overview of the field of pleural ultrasonography with an emphasis on clinical applicability and procedure guidance.

Sonographically guided thoracentesis and rate of pneumothorax

PURPOSE

To assess whether thoracenteses performed with sonographic guidance are associated with a lower rater of pneumothorax and tube thoracostomy than those performed without sonographic guidance.

METHODS

We reviewed the medical records of 523 subjects undergoing their initial diagnostic thoracentesis at our institution from July 1, 2001, to June 30, 2002. We excluded 73 subjects in whom no chest imaging had been performed within 5 days of thoracentesis or who had pre-existing chronic hydropneumothorax.

RESULTS

Of the 450 thoracenteses performed, 305 (67.8%) were performed with sonographic guidance and 145 (32.2%) were performed without. On postthoracentesis imaging in all subjects, 30 pneumothoraces (6.7%) were found (23 inpatients, 7 out-patients). Eight patients required a tube thoracostomy for their pneumothorax. Pneumothorax occurred in 15 of 305 procedures (4.9%) performed with sonographic guidance and 15 of 145 procedures (10.3%) performed without (p < 0.05). Tube thoracostomy was performed in 0.7% of patients whose thoracentesis was performed with sonographic guidance and in 4.1% in those that were not (p < 0.05). We found no correlation between pneumothorax after thoracentesis and age, inpatient status, loculation of effusion, or volume of pleural fluid removed.

CONCLUSIONS

The routine use of sonography during diagnostic thoracentesis is associated with a reduced rate of pneumothorax and tube thoracostomy.

Quantitative assessment of pleural effusion in critically ill patients by means of ultrasonography

OBJECTIVE

To assess the ability of ultrasonography to identify the presence and assess the volume of pleural effusion in the intensive care unit setting.

DESIGN

Prospective descriptive clinical study.

SETTING

Medical-surgical intensive care unit of a teaching hospital.

PATIENTS

Initial study group (group I) consisted of 97 patients (mean [+/-SD] Simplified Acute Physiology Score II, 40 +/- 14) with clinically suspected pleural effusion. Fifty-one patients were mechanically ventilated and 55 patients underwent a unilateral or bilateral thoracentesis (58 procedures). All patients underwent supine chest radiography and pleural ultrasonography at bedside. The testing group (group II) consisted of 19 additional patients (17 under ventilation) who underwent thoracentesis.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Maximal interpleural distance was measured at the base and apex of the pleural space, at both end-expiration and end-inspiration. In group I, interpleural distances were compared to actual volume of fluid in the subset of patients who underwent a complete thoracentesis (n = 49). Prediction of the volume of pleural effusion was subsequently tested prospectively in group II (25 complete thoracenteses). Portable chest radiography and pleural ultrasonography yielded discordant results for 47 patients (48%) in the diagnosis of pleural effusion. The expiratory interpleural distance measured at the thoracic base with ultrasonography was significantly correlated with the volume of fluid (p < .0001; coefficient of determination: right, 0.78; left, 0.51). A pleural effusion > or =800 mL was predicted when this distance was >45 mm (right) or >50 mm (left), with a sensitivity of 94% and 100% and a specificity of 76% and 67%, respectively. In group II, the mean bias between the predicted and observed volumes of pleural effusion determined by thoracentesis was 24 +/- 355 mL, and this decreased to 28 +/- 146 mL for the prediction of pleural effusion <1400 mL.

CONCLUSIONS

Bedside ultrasonography is well suited for the quantitative assessment of unloculated pleural effusions in intensive care unit patients.

Usefulness of ultrasonography in predicting pleural effusions > 500 mL in patients receiving mechanical ventilation

STUDY OBJECTIVE

To assess the accuracy of chest ultrasonography in predicting pleural effusions > 500 mL in patients receiving mechanical ventilation.

DESIGN

Prospective study.

SETTING

Surgical and medical ICU in a teaching hospital.

PATIENTS

Forty-four patients receiving mechanical ventilation with indications of chest drainage of a nonloculated pleural effusion.

INTERVENTIONS

Diagnosis of pleural effusion was based on clinical examination and chest radiography. Chest drainage was indicated when considered as potentially useful for the patient (hypoxemia and/or weaning failure). Sonograms were performed before drainage at the bedside, in the supine position, and measurements were performed at the end of expiration. Effusions were classified as > 500 mL or < or = 500 mL according to the drained volume.

MEASUREMENTS AND RESULTS

The drained volume ranged from 100 to 1,800 mL (mean, 730 +/- 440 mL [+/- SD]). The distance between the lung and posterior chest wall at the lung base (PLDbase) and the distance between the lung and posterior chest wall at the fifth intercostal space (PLD5) were significantly correlated with the drained volume (PLDbase, r = 0.68, p < 0.001; PLD5, r = 0.56, p < 0.001). A PLDbase > 5 cm predicted a drained volume > 500 mL with a sensitivity of 83%, specificity of 90%, positive predictive value of 91%, and negative predictive value of 82%. Interobserver and intraobserver percentages of error were, respectively, 7 +/- 6% and 9 +/- 6% for PLDbase, and 6 +/- 5% and 8 +/- 5% for PLD5. The PaO2/fraction of inspired oxygen ratio significantly increased after chest drainage in patients with collected volumes > 500 mL (p < 0.01).

CONCLUSIONS

Bedside pleural ultrasonography accurately predicted a nonloculated pleural effusion > 500 mL in patients receiving mechanical ventilation using simple and reproducible measurements.

Surgeon-performed ultrasound in the ICU setting

Evaluation of critically ill patients is often challenging due to altered sensorium, underlying disease, and the presence of multiple drains or monitoring devices. In such circumstances, the ability of physicians to perform ultrasound examinations in the intensive care unit provides a useful diagnostic and therapeutic adjunct. In this article,we review the application of surgeon-performed ultrasonography in the evaluation and management of critically ill patients.

The effect of tube thoracostomy on oxygenation in ICU patients

Previous research found that in noncritically ill patients, thoracocentesis has an unpredictable effect on oxygenation, possibly due to re-expansion pulmonary edema and systemic hypotension. The authors performed a retrospective analysis to study the effect of tube thoracostomy on oxygenation in ICU patients, and the complications associated with it. The authors reviewed the charts of 58 ICU patients in whom 74 procedures were performed. Demographic data, APACHE II score, and indication for thoracocentesis were retrieved from the patient's file. The P(a)O(2)/FiO(2) ratio was calculated before, 12, 24, and 48 hours after tube thoracostomy. P(a)O(2)/FiO(2) ratios at the mentioned time intervals were compared using 1-way analysis of variances (ANOVA) with repeated measures. Logistic regression analysis was used to identify factors associated with a good response to treatment. Age of the patients was 53 +/- 19.0 years (range, 17-88), APACHE II score was 21 +/- 8.3 (range, 6-38), and median length of stay was 13.5 days (interquartile range, 7-25). The volume drained during the first 24 hours was 1077 +/- 667 ml. P(a)O(2)/FiO(2) ratio was 185 +/- 79.3 before chest drainage, 197 +/- 79.1 at 12 hours, 217 +/- 88.9 at 24 hours, and 233 +/- 99.8 at 48 hours. In only 54% of the procedures, a response to therapy was present. Multivariate analysis identified a P(a)O(2)/FiO(2) below 180 to be independently associated with improvement in oxygenation. At 24 and 48 hours, the P(a)O(2)/FiO(2) ratio was significantly higher than before drainage (P <.001). There were 13 complications in 11 procedures (14.9%). The authors' results suggest that tube thoracostomy can be used as an adjunct in the treatment of selected patients with hypoxemic respiratory failure in the ICU. A low P(a)O(2)/FiO(2) seems to be a good predictor of response to therapy. However, the complication rate is considerable, especially in patients with a prolonged ICU stay.