Current Trends in the Use of Ultrasound Over Chest X-Ray to Identify Pneumothoraces in ICU, Trauma, and ARDS Patients

Pneumothoraces are a common and potentially fatal complication for critically ill patients in the trauma and intensive care units. Since its use for pneumothorax detection was first reported in 1987, ultrasound has been increasingly used for the detection of thoracic injuries. As ultrasound imaging has improved and operators have potentially become more proficient, it is important to analyze more recent trends in the sensitivities and specificities of ultrasound for the detection of pneumothorax. This literature review and meta-analysis identifies 17 studies that directly compare the sensitivity and specificity of ultrasound and anterior-posterior chest x-ray in the identification of pneumothorax among 2955 patients who developed 793 pneumothoraces as detected by gold standard CT scanning. For the 17 articles analyzed, the pooled sensitivity of trans-thoracic ultrasound was 75.07% (64.92%-85.22%), and the pooled specificity was 98.36% (97.45%-99.26%). The pooled sensitivity of CXR was 45.65% (36.04%-55.26%), and pooled specificity was 99.62% (99.00%-100%). While this review demonstrates an improved sensitivity in the detection of pneumothorax with ultrasound over AP chest x-rays, it did not find a significant trend or improvement in the sensitivity or specificity of ultrasound for detecting pneumothorax over time.

COVID-19 with cystic features on computed tomography: A case report

RATIONALE

The cystic features of the novel coronavirus disease 2019 (COVID-19) found on computed tomography (CT) have not yet been reported in the published literature. We report the cystic chest CT findings of 2 patients confirmed to have COVID-19-related pneumonia.

PATIENT CONCERNS

A 38-year-old man and a 35-year-old man diagnosed with severe COVID-19 pneumonia were admitted to the intensive care unit.

DIAGNOSES

Chest CT findings showed multiple cysts in ground-glass opacities (bilaterally) with/without pneumothorax. The cysts had a smooth inner wall.

INTERVENTIONS

The patients continued to be given oxygen by mask and received antitussive, phlegm-dispelling treatment.

OUTCOMES

At follow up, there was a reduction in the number of multiple cystic lesions on CT. To date, 1 patient was discharged from hospital, while the other had been transferred to the rehabilitation department.

LESSONS

COVID-19 may independently result in pulmonary cyst formation and pneumothorax; the application of a ventilator may be another causative factor.

Thoracic abnormal air collections in patients in the intensive care unit: radiograph findings correlated with CT

An abnormal collection of air in the thorax is one of the most common life-threatening events that occurs in the intensive care unit. Patient management differs depending on the location of the air collection; therefore, detecting abnormal air collection and identifying its exact location on supine chest radiographs is essential for early treatment and positive patient outcomes. Thoracic abnormal air collects in multiple thoracic spaces, including the pleural cavity, chest wall, mediastinum, pericardium, and lung. Pneumothorax in the supine position shows different radiographic findings depending on the location. Many conditions, such as skin folds, interlobar fissure, bullae in the apices, and air collection in the intrathoracic extrapleural space, mimic pneumothorax on radiographs. Additionally, pneumopericardium may resemble pneumomediastinum and needs to be differentiated. Further, some conditions such as inferior pulmonary ligament air collection versus a pneumatocele or pneumothorax in the posteromedial space require a differential diagnosis based on radiographs. Computed tomography (CT) is required to localize the air and delineate potential etiologies when a diagnosis by radiography is difficult. The purposes of this article are to review the anatomy of the potential spaces in the chest where abnormal air can collect, explain characteristic radiographic findings of the abnormal air collection in supine patients with illustrations and correlated CT images, and describe the distinguishing features of conditions that require a differential diagnosis. Since management differs based on the location of the air collection, radiologists should try to accurately detect and identify the location of air collection on supine radiographs.

Imaging of Diffuse Lung Disease in the Intensive Care Unit Patient

There is a wide variety of causes of diffuse lung disease in the intensive care unit patient, of which adult respiratory distress syndrome is the commonest clinical consideration. Plain radiography, computed tomography, and ultrasound can be used synergistically to evaluate patients with diffuse lung disease and respiratory impairment. Imaging is not limited to characterization of the cause of diffuse lung disease but also aids in monitoring its evolution and in ventilator setting management.

Imaging the Injured Lung: Mechanisms of Action and Clinical Use

Acute respiratory distress syndrome (ARDS) consists of acute hypoxemic respiratory failure characterized by massive and heterogeneously distributed loss of lung aeration caused by diffuse inflammation and edema present in interstitial and alveolar spaces. It is defined by consensus criteria, which include diffuse infiltrates on chest imaging-either plain radiography or computed tomography. This review will summarize how imaging sciences can inform modern respiratory management of ARDS and continue to increase the understanding of the acutely injured lung. This review also describes newer imaging methodologies that are likely to inform future clinical decision-making and potentially improve outcome. For each imaging modality, this review systematically describes the underlying principles, technology involved, measurements obtained, insights gained by the technique, emerging approaches, limitations, and future developments. Finally, integrated approaches are considered whereby multimodal imaging may impact management of ARDS.

Metabolomics based predictive biomarker model of ARDS: A systemic measure of clinical hypoxemia

Despite advancements in ventilator technologies, lung supportive and rescue therapies, the outcome and prognostication in acute respiratory distress syndrome (ARDS) remains incremental and ambiguous. Metabolomics is a potential insightful measure to the diagnostic approaches practiced in critical disease settings. In our study patients diagnosed with mild and moderate/severe ARDS clinically governed by hypoxemic P/F ratio between 100-300 but with indistinct molecular phenotype were discriminated employing nuclear magnetic resonance (NMR) based metabolomics of mini bronchoalveolar lavage fluid (mBALF). Resulting biomarker prototype comprising six metabolites was substantiated highlighting ARDS susceptibility/recovery. Both the groups (mild and moderate/severe ARDS) showed distinct biochemical profile based on 83.3% classification by discriminant function analysis and cross validated accuracy of 91% using partial least squares discriminant analysis as major classifier. The predictive performance of narrowed down six metabolites were found analogous with chemometrics. The proposed biomarker model consisting of six metabolites proline, lysine/arginine, taurine, threonine and glutamate were found characteristic of ARDS sub-stages with aberrant metabolism observed mainly in arginine, proline metabolism, lysine synthesis and so forth correlating to diseased metabotype. Thus NMR based metabolomics has provided new insight into ARDS sub-stages and conclusively a precise biomarker model proposed, reflecting underlying metabolic dysfunction aiding prior clinical decision making.

Radiology in the Intensive Care Unit (Part 2)

This review of intensive care unit (ICU) radiology has been divided into two sections. In Part 1, previously published, the discussion focused on the role of the portable radiograph in the evaluation of the critically ill patient and the impact of the introduction of digital radiography and picture-archiving communications systems on patient care. Part 2 of this review will emphasize the role of computed tomography and the increasing contribution of image-guided interventional procedures in patient management. The deleterious effects of mechanical ventilation due to barotrauma will also be discussed.

Overview of current lung imaging in acute respiratory distress syndrome

Imaging plays a key role in the diagnosis and follow-up of acute respiratory distress syndrome (ARDS). Chest radiography, bedside lung ultrasonography and computed tomography scans can provide useful information for the management of patients and detection of prognostic factors. However, imaging findings are not specific and several possible differential diagnoses should be taken into account. Herein we will review the role of radiological techniques in ARDS, highlight the plain radiological and computed tomography findings according to the pathological stage of the disease (exudative, inflammatory and fibroproliferative), and summarise the main points for the differential diagnosis with cardiogenic oedema, which is still challenging in the acute stage.

The pathophysiology of perioperative lung injury

The degree of perioperative lung injury that patients sustain results from a complex interaction between their current physiologic state, comorbidities, lifestyle choices, underlying surgical diagnosis, operative, and ultimately their cardiopulmonary interaction with a mechanical ventilator. This review addresses primarily the pathophysiology of perioperative lung injury with reference to ventilator-induced lung injury and acute respiratory distress syndrome.

Lung aeration changes after lung recruitment in children with acute lung injury: a feasibility study

RATIONALE

There are several adult studies using computed tomography (CT-scan) to examine lung aeration changes during or after a recruitment maneuver (RM) in ventilated patients with acute lung injury (ALI). However, there are no published data on the lung aeration changes during or after a RM in ventilated pediatric patients with ALI.

OBJECTIVE

To describe CT-scan lung aeration changes and gas exchange after lung recruitment in pediatric ALI and assess the safety of transporting patients in the acute phase of ALI to the CT-scanner.

METHODS

We present a case series completed in a subset of six patients enrolled in our previously published study of efficacy and safety of lung recruitment in pediatric patients with ALI.

INTERVENTION

RM using incremental positive end-expiratory pressure.

RESULTS

There was a variable increase in aerated and poorly aerated lung after the RM ranging from 3% to 72% (median 20%; interquartile range 6, 47; P = 0.03). All patients had improvement in the ratio of partial pressure of arterial oxygen over fraction of inspired oxygen (PaO(2) /FiO(2)) after the RM (median 14%; interquartile range: 8, 72; P = 0.03). There was a decrease in the partial pressure of arterial carbon dioxide (PaCO(2)) in four of six subjects after the RM (median -5%; interquartile range: -9, 2; P = 0.5). One subject had transient hypercapnia (41% increase in PaCO(2)) during the RM and this correlated with the smallest increase (3%) in aerated and poorly aerated lung. All patients tolerated the RM without hemodynamic compromise, barotrauma, hypoxemia, or dysrhythmias.

CONCLUSIONS

Lung recruitment results in improved lung aeration as detected by lung tomography. This is accompanied by improvements in oxygenation and ventilation. However, the clinical significance of these findings is uncertain. Transporting patients in early ALI to the CT-scanner seems safe and feasible.

The influence of autonomic dysfunction associated with aging and type 2 diabetes on daily life activities

Type 2 diabetes (T2D) and ageing have well documented effects on every organ in the body. In T2D the autonomic nervous system is impaired due to damage to neurons, sensory receptors, synapses and the blood vessels. This paper will concentrate on how autonomic impairment alters normal daily activities. Impairments include the response of the blood vessels to heat, sweating, heat transfer, whole body heating, orthostatic intolerance, balance, and gait. Because diabetes is more prevalent in older individuals, the effects of ageing will be examined. Beginning with endothelial dysfunction, blood vessels have impairment in their ability to vasodilate. With this and synaptic damage, the autonomic nervous system cannot compensate for effectors such as pressure on and heating of the skin. This and reduced ability of the heart to respond to stress, reduces autonomic orthostatic compensation. Diminished sweating causes the skin and core temperature to be high during whole body heating. Impaired orthostatic tolerance, impaired vision and vestibular sensing, causes poor balance and impaired gait. Overall, people with T2D must be made aware and counseled relative to the potential consequence of these impairments.

Ventilator-induced lung injury: the anatomical and physiological framework

Since its introduction into the management of the acute respiratory distress syndrome, mechanical ventilation has been so strongly interwoven with its side effects that it came to be considered as invariably dangerous. Over the decades, attention has shifted from gross barotrauma to volutrauma and, more recently, to atelectrauma and biotrauma. In this article, we describe the anatomical and physiologic framework in which ventilator-induced lung injury may occur. We address the concept of lung stress/strain as applied to the whole lung or specific pulmonary regions. We challenge some common beliefs, such as separately studying the dangerous effects of different tidal volumes (end inspiration) and end-expiratory positive pressures. Based on available data, we suggest that stress at rupture is only rarely reached and that high tidal volume induces ventilator-induced lung injury by augmenting the pressure heterogeneity at the interface between open and constantly closed units. We believe that ventilator-induced lung injury occurs only when a given threshold is exceeded; below this limit, mechanical ventilation is likely to be safe.

Multi-detector computed tomography in critically ill patients

BACKGROUND

There is a lack of studies showing the overall impact of multi-detector computed tomography (MDCT) on the treatment of critically ill patients in a general intensive care unit (ICU) setting.

METHODS

A prospective observational study on the effects of MDCT on the treatment of patients in a 12-bed medical-surgical ICU in a university hospital providing tertiary care.

RESULTS

During the 9-month study period, there were 343 admissions with ICU length of stay longer than 48 h. Of these patients, 64 (19%) had had inconclusive findings with other modalities of radiological imaging, and they underwent altogether 82 MDCT examinations. Fifty examinations (61%) resulted in a change of treatment. The changes included 22 surgical interventions, 16 percutaneous or paranasal interventions, 15 changes of antimicrobial therapy, three withdrawals of active treatment, and four other changes of treatment. Eight patients underwent two and one patient underwent three changes of treatment. Twenty examinations (24%) were regarded as otherwise necessary for clinical decision-making, although no change in the treatment was indicated. Twelve examinations (15%) failed to provide any additional information relevant to the patient's treatment.

CONCLUSION

Sixty-one percent of the MDCT examinations led to a change of treatment, and 24% of them otherwise contributed to or supported clinical decision-making, suggesting that MDCT examination is helpful in the case of general ICU patients, with inconclusive findings with other imaging modalities.

Prevalence and characteristics of pleural effusions in superior vena cava syndrome

OBJECTIVE AND BACKGROUND

The prevalence and characteristics of pleural effusions occurring in adults with the superior vena cava (SVC) syndrome are unknown. The purpose of the present study was to characterize these pleural effusions.

METHODS

Charts of patients diagnosed with SVC syndrome at a tertiary care referral centre were reviewed. Radiographs were evaluated for the presence and size of pleural effusions, presence and location of masses and mediastinal width. If a pleural effusion was present, the patient's chart and a pre-existing database on pleural effusions were searched to determine whether the effusion was sampled and the results of any laboratory investigations on the fluid.

RESULTS

The SVC syndrome occurred in 78 patients. Malignancy was the aetiology in 60% of the cases and bronchogenic carcinoma was the most common malignancy. An intravascular device was the aetiology in the majority of benign cases. Pleural effusion was found in 70% of patients with a malignant aetiology and 58% of those with a benign cause (P=0.345). The mean size of the effusions was larger in malignant cases (P=0.012). Of the 44 effusions 22 were sampled (17 in malignancy and five with benign processes); none was transudates, 20 (91%) were exudative (four of these were chylous) and the remaining two were reported as exudates but did not have pleural chemistries documented.

CONCLUSIONS

More than half of patients with SVC syndrome have pleural effusions, regardless of the aetiology. However, the effusions are larger when associated with malignancy. The majority of these effusions are exudative and occasionally chylous. None was transudates.

Centromere DNA, proteins and kinetochore assembly in vertebrate cells

The centromere is a specialized region of the chromosome that is essential for faithful chromosome segregation during mitosis and meiosis in eukaryotic cells. It is the site at which the kinetochore, the functional nucleoprotein complex responsible for microtubule binding and chromosome movement, is assembled through complex molecular mechanisms. Herein, I review recent advances in our understanding of centromeric DNAs as sites for kinetochore assembly and the mechanisms underlying kinetochore assembly in vertebrate cells.

Non-traumatic postmortem computed tomographic (PMCT) findings of the lung

PURPOSE

We attempted to obtain postmortem computed tomographic (PMCT) images of the lung in cases of non-traumatic death and describe the results to distinguish usual postmortem findings from those of specific thoracic causes of death.

MATERIALS AND METHODS

Our subjects were a total of 150 consecutive non-traumatic cases with cardiopulmonary arrest on arrival who were examined by CT within 2h after certification of death between January 1993 and December 2001. PMCT images of the lung and the frequency of imaging findings (dependent density, ground glass attenuation (GGA), consolidation, pleural effusion, and endotracheal (or endobronchial) air defect) were retrospectively reviewed. Autopsy had been conducted in 16 of the cases.

RESULTS

The causes of death and frequency percentages of dependent density, GGA, consolidation, pleural effusion, and endotracheal (or endobronchial) air defect were: 91 cases of acute heart failure (AHF) (69, 66, 24, 11, 14%), 23 cases of aortic dissection (57, 39, 4, 52, 0%), 11 cases of pneumonia (18, 82, 100, 45, 27%), 23 other specified cases (52, 30, 13, 17, 9%), and two unspecified cases (0, 0, 0, 50, 0%), [total respective frequency percentages were (60, 57, 25, 21, 12%)]. Autopsy confirmed that GGA on PMCT in AHF cases corresponded to pulmonary edema.

CONCLUSION

When PMCT of the lung shows no other shadows than dependent density, further analysis is necessary to detect the cause of death.

Drug-induced lung disease: high-resolution CT and histological findings

AIM

To compare the parenchymal high-resolution computed tomography (HRCT) appearances with histological findings in patients with drug-induced lung disease and to determine the prognostic value of HRCT.

MATERIALS AND METHODS

Drug history, HRCT features, histological findings and outcome at 3 months in 20 patients with drug induced-lung disease were reviewed retrospectively. The HRCT images were assessed for the pattern and distribution of abnormalities and classified as most suggestive of interstitial pneumonitis/fibrosis, diffuse alveolar damage (DAD), organizing pneumonia (OP) reaction, or a hypersensitivity reaction.

RESULTS

On histopathological examination there were eight cases of interstitial pneumonitis/fibrosis, five of DAD, five of OP reactions, one of hypersensitivity reaction and one of pulmonary eosinophilia. The most common abnormalities on HRCT were ground-glass opacities (n = 17), consolidation (n = 14), interlobular septal thickening (n = 15) and centrilobular nodules (n = 8). HRCT interpretation and histological diagnosis were concordant in only nine (45%) of 20 patients. The pattern, distribution, and extent of HRCT abnormalities were of limited prognostic value: all eight patients with histological findings of OP, hypersensitivity reaction, or eosinophilic infiltrate improved on follow-up compared to only five of 13 patients with interstitial pneumonitis/fibrosis or DAD.

CONCLUSION

In many cases of drug-induced lung injury HRCT is of limited value in determining the histological pattern and prognosis.

Radiologic features of all-trans-retinoic acid syndrome

OBJECTIVE

The treatment of acute promyelocytic leukemia with all-trans-retinoic acid (ATRA) sometimes results in a syndrome characterized by fever, respiratory distress, weight gain, pleural and pericardial effusion, and pulmonary infiltrates. We report the radiologic features of ATRA syndrome.

MATERIALS AND METHODS

During the past 5 years, 69 patients with acute promyelocytic leukemia were treated with ATRA. Of this group, 15 patients developed ATRA syndrome. Serial chest radiographs of the 15 patients with ATRA syndrome were evaluated retrospectively for the presence of pleural effusion, pulmonary nodules, consolidation, ground-glass opacity, septal lines, increased pulmonary blood volume, peribronchial cuffing, and air bronchogram. Also, we measured the cardiothoracic ratio and the vascular pedicle width.

RESULTS

Chest radiographs showed increased cardiothoracic ratio in 13 of the 15 patients, increased vascular pedicle width in 13, increased pulmonary blood volume in 13, septal lines in nine, peribronchial cuffing in nine, ground-glass opacity in nine, consolidation in seven, and nodules in seven. Pleural effusion was noted in 11 of the 15 patients, and air bronchogram was noted in five of the 15 patients. Pulmonary hemorrhage developed in three patients who were being treated with ATRA; they showed bilateral, diffuse, poorly defined nodules and ground-glass opacity on radiography.

CONCLUSION

Most patients with ATRA syndrome have abnormal findings on chest radiographs, and the abnormalities are similar to those of pulmonary edema.

Current concepts in adult respiratory distress syndrome in children

Acute respiratory distress syndrome (ARDS) is an acute form of severe alveolar-capillary injury that evolves after a direct or indirect lung insult. It begins as noncardiogenic pulmonary edema and develops into a neutrophilic alveolitis, and, later, pulmonary fibrosis. Mortality remains high among children with ARDS, particularly when serious underlying conditions co-exist, sepsis occurs, and when there is multi-organ failure. Lung function improves with time among survivors, but pulmonary fibrosis may persist. Advances in the care of children with ARDS include the use of lung-protective ventilator strategies, permissive hypercapnia, inhaled nitric oxide, high-frequency ventilation, and extra-corporeal life support. These approaches reduce ventilator-associated lung injury and may improve survival when used in combination with one another. Interventions that reduce alveolar inflammation, enhance alveolar fluid removal, and reduce pulmonary fibrosis will further improve survival and recovery from ARDS in the future.

Acute respiratory distress syndrome and acute interstitial pneumonia: comparison of thin-section CT findings

PURPOSE

The purpose of this work was to compare the thin-section CT findings of acute respiratory distress syndrome (ARDS) with those of acute interstitial pneumonia (AIP).

METHOD

The thin-section CT scans from 25 patients with ARDS and 25 with AIP were independently assessed by two observers without knowledge of clinical and pathologic data. The presence, extent, and distribution of various CT findings were independently analyzed.

RESULTS

Honeycombing was seen more frequently in lobes of patients with AIP (26%) than in lobes with ARDS (8%) (p < 0.001). Compared with patients with ARDS, a greater number of patients with AIP had a predominantly lower lung zone distribution (p < 0.05) and a symmetric distribution (p < 0.05) of the parenchymal abnormalities.

CONCLUSION

Patients with AIP have a greater prevalence of honeycombing and are more likely to have a symmetric bilateral distribution and a lower lung zone predominance than patients with ARDS. However, significant overlap exists among the CT findings.

Pleural Disease in the Intensive Care Unit

Pleural disease itself is an unusual cause for admission to the intensive care unit (ICU). Pleural complications of diseases and procedures in the ICU are common, however, and the impact on respiratory physiology is additive to that of the underlying cardiopulmonary disease. Pleural effusion and pneumothorax may be overlooked in the critically ill patient due to alterations in radiologic appearance in the supine patient. The development of a pneumothorax in a patient in the ICU represents a potentially life-threatening situation. This article reviews the etiologies, pathophysiology, and management of pleural effusion, pneumothorax, tension pneumothorax, and bronchopleural fistula in the critically ill patient. In addition, we review the potential complications of thoracentesis and chest tube thoracostomy, including re-expansion pulmonary edema.

Pulmonary fat embolism syndrome: CT findings in six patients

PURPOSE

Our purpose is to describe the CT findings in pulmonary fat embolism syndrome (FES).

METHOD

Chest radiographs and CT scans of six patients with pulmonary FES were reviewed. Initial and follow-up CT findings were noted, and the extent of CT abnormalities was correlated with partial pressure of arterial oxygen (PaO2).

RESULTS

Focal areas of consolidation or ground-glass opacity and nodules were seen in all patients, predominantly in the upper lobes of the lungs. Association between these opacities and pulmonary vessels was indicated in three patients. In the lower lobes of all patients, gravity-dependent opacities predominated. Diffuse ground-glass opacity was noted in five patients. Follow-up CT scans showed rapid improvement in three patients, but the gravity-dependent opacity progressed. The extent of CT abnormalities correlated positively with PaO2 (r = 0.8, p < 0.05).

CONCLUSION

CT findings reflect the pathophysiology of this syndrome, which differs from that of simple capillary permeability pulmonary edema.

Herpes simplex virus 1 pneumonia: patterns on CT scans and conventional chest radiographs

PURPOSE

The goal of our study was to describe the herpes simplex virus type 1 (HSV 1) pneumonia patterns on CT scans and chest radiographs.

METHOD

We retrospectively reviewed clinical records and chest radiographs of 24 patients with HSV 1 pneumonia and 10 with pneumonia from combined HSV and mixed flora infection. We also reviewed CT scans available for eight patients with HSV pneumonia and four with mixed pneumonia.

RESULTS

CT scans of eight patients with HSV pneumonia demonstrated multifocal segmental and subsegmental ground-glass opacities (n = 8), additional focal areas of consolidation (n = 6), scattered distribution (n = 6), and pleural effusions (n = 7). Chest radiographs (23 patients) showed patchy segmental and subsegmental ground-glass opacities and consolidation (n = 23), scattered distribution (n = 20), and pleural effusions (n = 12). Radiographic patterns for isolated HSV pneumonia and mixed flora pneumonia were not significantly different.

CONCLUSION

With a growing population of at-risk immunosuppressed patients, it is important to recognize CT and chest radiography patterns consistent with, although nonspecific for, HSV 1 pneumonia.

Recurrent pneumothoraces in ventilated patients despite ipsilateral chest tubes

The incidence of recurrent pneumothoraces was analyzed in mechanically ventilated patients with the adult respiratory distress syndrome (ARDS) or non-ARDS causes of respiratory failure who had ipsilateral chest tubes in place. The radiographs of 39 consecutive patients with 47 initial pneumothoraces were evaluated for pneumothorax recurrence and chest tube positioning, which was prospectively defined as having a "vertical" or "horizontal" orientation. "Horizontal" positioning indicated that the chest tube may have been placed into a major fissure or the posterior hemithorax. Sixteen of the 47 pneumothoraces in all study patients, 14 of the 21 pneumothoraces in patients with ARDS, and 2 of the 26 pneumothoraces in patients without ARDS recurred (p < 0.0001) despite an ipsilateral chest tube; 9 of the 14 ARDS pneumothorax recurrences were tension types. "Horizontal" chest tube positioning in patients with ARDS had a positive predictive value of 86% and 64% for recurrences of pneumothoraces and tension pneumothoraces, respectively. Recurrent pneumothoraces occur commonly in mechanically ventilated patients with ARDS despite ipsilateral chest tubes. Because pneumothorax recurrences appear to be related to horizontal chest tube placement, imaging studies should verify that chest tubes are placed in optimally in the anterior hemithorax away from interlobar fissures in this patient population.