Medical and surgical management of pneumothorax in diving and hyperbaric chambers.

The presence of a pneumothorax within a pressurized chamber represents unique diagnostic and management challenges. This is particularly the case in the medical and geographic remoteness of many chamber locations. Upon commencing chamber decompression, unvented intrapleural air expands. If its initial volume and/or degree of chamber pressure reduction is significant enough, a tension pneumothorax will result. Numerous reports chronicle failure to diagnose and manage in-chamber pneumothorax with resultant morbidity and one fatal outcome. Such cases have occurred in both medically remote and clinically based settings. This paper reviews pneumothorax and tension pneumothorax risk factors and clinical characteristics. It suggests primary medical management using the principle of oxygen-induced inherent unsaturation in concert with titrated chamber decompression designed to prevent intrapleural air expanding faster than it contracts. Should this conservative approach prove unsuccessful, and surgical venting becomes necessary or otherwise immediately indicated, interventional options are reviewed.

The sensitivity of a neck CT scan in detecting pneumothoraces in nonpenetrating trauma.

BACKGROUND: The trauma-related pneumothorax is a common intrathoracic injury and can go undetected with detrimental outcomes. Chest computed tomography (CT) investigation in low- to middle-income countries (LMIC) is not always readily available during emergency situations and increased workloads. However, alternative investigations all have limitations in including pneumothoraces. Patients may have trauma indications for CT of the head and neck. The neck CT scan may hold an extra potential advantage in pneumothorax detection. This study aimed to assess its sensitivity in pneumothorax detection in nonpenetrating trauma. METHODS: A retrospective study was conducted from 1 January 2016 to 31 December 2021. All adult patients sustaining nonpenetrating injuries, and investigated with chest and neck CT scans were included. The chest CT scan was the gold standard against,which the neck CT scan was compared to determine the accuracy of pneumothorax detection. Stata version 16 was used for descriptive statistical analysis, and a p-value of 0.05 was considered statistically significant. RESULTS: One thousand ninety three were eligible for evaluation; 204 (18.66%) pneumothoraces were detected on chest CT scans, 200 (98.0%) of which were also detected on the neck CT scan, producing a sensitivity of 98.0% (95% CI 95.1-99.5%) and a specificity of 100% (95% CI 99.6-100%). Most pneumothoraces were detected at T1 level (45.09%), followed by T2 (43.62%). CONCLUSION: The neck CT scan has demonstrated high sensitivity and specificity in pneumothorax detection. Thus, it may be used as an additional tool for those who could not receive or do not need a formal chest CT but have an indication for neck CT scans.

An 88-Year-Old Woman With Pneumothorax and Black Pleural Effusion.

CASE PRESENTATION: An 88-year-old woman was admitted to our hospital with the sudden onset of dyspnea after eating. The patient had undergone nephrectomy for a left renal tumor 24 years previously. The patient had been prescribed ferrous citrate for iron-deficiency anemia. She complained of appetite loss a few days before admission but had no abdominal pain. CT scan showed no abnormalities in the lungs but a mass in the liver.

Prospective Observation Study for Primary Spontaneous Pneumothorax: Incidence of and Risk Factors for Postoperative Neogenesis of Bullae.

PURPOSE: Details of the neogenesis of bullae (NOB), which causes recurrent primary spontaneous pneumothorax (PSP) following bullectomy, have not been reported and risk factors for NOB remain unclear. We aimed to clarify the details of NOB. METHODS: We conducted a prospective study using three computed tomography (CT) examinations performed 6, 12, and 24 months after bullectomy to identify the incidence of and risk factors for NOB. We enrolled 50 patients who underwent bullectomy for PSP. RESULTS: After excluding 11 patients who canceled the postoperative CT examination at 6 months after bullectomy, only 39 patients were analyzed. The incidence of NOB at 6, 12, and 24 months after bullectomy was 38.5%, 55.2%, and 71.2%, respectively. The rate of NOB in the operated lung was almost 2 times higher than that in the contralateral nonoperative lung. Male sex, multiple bullae on preoperative CT, long stapling line (≥7 cm), deep stapling depth (≥1.5 cm), and heavier resected sample (≥5 g) were suggested to be risk factors for NOB. CONCLUSIONS: We recognized a high incidence of postoperative NOB in PSP patients. Bullectomy itself seems to promote NOB. Postoperative NOB occurs frequently, especially in patients who require a large-volume lung resection with a long staple line.

Utility of artificial intelligence for detection of pneumothorax on chest radiopgraphs done after transthoracic percutaneous transthoracic biopsy guided by computed tomography.

OBJETIVE: To assess the ability of an artificial intelligence software to detect pneumothorax in chest radiographs done after percutaneous transthoracic biopsy. MATERIAL AND METHODS: We included retrospectively in our study adult patients who underwent CT-guided percutaneous transthoracic biopsies from lung, pleural or mediastinal lesions from June 2019 to June 2020, and who had a follow-up chest radiograph after the procedure. These chest radiographs were read to search the presence of pneumothorax independently by an expert thoracic radiologist and a radiodiagnosis resident, whose unified lecture was defined as the gold standard, and the result of each radiograph after interpretation by the artificial intelligence software was documented for posterior comparison with the gold standard. RESULTS: A total of 284 chest radiographs were included in the study and the incidence of pneumothorax was 14.4%. There were no discrepancies between the two readers' interpretation of any of the postbiopsy chest radiographs. The artificial intelligence software was able to detect 41/41 of the present pneumothorax, implying a sensitivity of 100% and a negative predictive value of 100%, with a specificity of 79.4% and a positive predictive value of 45%. The accuracy was 82.4%, indicating that there is a high probability that an individual will be adequately classified by the software. It has also been documented that the presence of Port-a-cath is the cause of 8 of the 50 of false positives by the software. CONCLUSIONS: The software has detected 100% of cases of pneumothorax in the postbiopsy chest radiographs. A potential use of this software could be as a prioritisation tool, allowing radiologists not to read immediately (or even not to read) chest radiographs classified as non-pathological by the software, with the confidence that there are no pathological cases.

Refractory Pneumothorax Due to Cystic Pulmonary Metastasis of a Lowgrade Endometrial Stromal Sarcoma: A Case Report.

Low-grade endometrial stromal sarcoma (LG-ESS) is a rare uterine neoplasm. Computed tomography (CT) revealed the presence of multiple small bilateral pulmonary nodules in a 58-year-old woman 1 year after surgery for LG-ESS; the clinical diagnosis was pulmonary metastasis. Hormone therapy with progesterone was initiated, after which most of the solid nodules disappeared and some transformed into cystic lesions. Seven years after hormone therapy, the patient experienced repeated pneumothorax. The cause of the pneumothorax was perforation of a metastatic focus within the wall of a small subpleural cyst that was not evident on CT images.

Occult solitary fibrous tumour of the pleura presenting as recurrent spontaneous pneumothorax.

A woman in her 30s, non-smoker, presented at the emergency department two times because of spontaneous pneumothorax. The first episode was treated with small bore catheter drainage, while during the second episode-occurring only 1 week later-thoracoscopic talcage was attempted. The postoperative course was characterised by slow clinical and radiological resolution, and recurrence 3 days after discharge. Eventually, multiportal video-assisted thoracoscopic exploration identified an interfissural solid mass. Resection and further work-up revealed the diagnosis of 'low-risk' solitary fibrous tumour (SFT) stage pT1N0M0. The interdisciplinary tumour board advised no adjuvant therapy. A CT thorax was scheduled in 1 year for follow-up. The patient was discharged without complications and has had no recurrences of pneumothorax at 6 months of follow-up. This report shows that SFT can easily be missed on initial presentation and should be considered in the differential diagnosis of pneumothorax, especially when frequently recurring.

Nasogastric tube placement perforating the nasopharynx causing mediastinal passage and feeding into the pleural space.

A mid-60s female with known primary progressive multiple sclerosis was admitted to our hospital with aspiration pneumonia. Due to reduced consciousness, a nasogastric (NG) tube was inserted for feeding. A chest x-ray (CXR) report from a thoracic radiologist confirmed an atypical tip position due to a hiatus hernia but concluded it was almost certainly within the stomach. However, after deteriorating on feed commencement, a CT scan of the chest confirmed the tube had perforated the nasopharynx and run parallel to the oesophagus through the mediastinum into the right pleural space. The patient subsequently developed an empyema and pneumothorax, requiring multiple therapeutic interventions and a prolonged hospital stay. This case demonstrates how the routine insertion of an NG tube can lead to serious complications. Additionally, position check CXRs can be difficult to interpret, so the decision to use the tube must be made cautiously by the clinical team.

Macklin Effect: From Pathophysiology to Clinical Implication.

Air leak syndromes (such as pneumomediastinum, pneumothorax, or subcutaneous emphysema) are frequent complications of acute respiratory distress syndrome (ARDS). Unfortunately, the development of air leaks is associated with worse outcomes. In addition, it has been hypothesized that the development of pneumomediastinum could be a marker of disease severity in patients with respiratory failure receiving noninvasive respiratory support or assisted ventilation. The so-called Macklin effect (or pulmonary interstitial emphysema) is the air dissection of the lung bronchovascular tree from peripheral to central airways following injury to distal alveoli. Ultimately, the progression of the Macklin effect leads to the development of pneumomediastinum, subcutaneous emphysema, or pneumothorax. The Macklin effect is identifiable on a chest computed tomography (CT) scan. The Macklin effect could be an accurate predictor of barotrauma in patients with ARDS (sensitivity = 89.2% [95% CI: 74.6-96.9]; specificity = 95.6% [95% CI: 90.6-98.4]), and may be a marker of disease severity. Accordingly, the detection of the Macklin effect on a chest CT scan could be used to select which patients with ARDS might benefit from different treatment algorithms, including advanced respiratory monitoring, early intubation, or, potentially, the institution of early extracorporeal support with or without invasive ventilation. In this video, the authors summarize the pathophysiology and potential clinical significance and applications of the Macklin effect in patients with acute respiratory failure.

Physical examination and CT to assess thoracic injury in 137 cats presented to UK referral hospitals after trauma.

OBJECTIVES: The aim of the study was to describe clinical examination and thoracic CT (TCT) findings in cats after trauma, and to identify physical examination findings associated with both abnormalities on TCT and the need for therapeutic interventions. METHODS: A multicentre, retrospective, observational study was conducted. Cats admitted to the participating hospitals with a history of blunt trauma and that underwent TCT were eligible. Data were collected on signalment, history, physical examination, TCT findings and subsequent interventions. RESULTS: In total, 137 cats were included. Road traffic accidents (RTAs) were the most frequently reported cause of trauma (69%). Tachypnoea (32%), pale mucous membranes (22%) and dyspnoea (20%) were the most common abnormal findings on thoracic examination. The most frequently identified thoracic pathologies on TCT were atelectasis (34%), pulmonary contusions (33%), pneumothorax (29%) and pleural effusion (20%). Thoracocentesis was the most commonly performed intervention (12%), followed by chest drain placement (7%). A total of 45 (33%) cats had no physical examination abnormalities but did have abnormalities detected on TCT; six of these cats required interventions. Increasing numbers of thoracic abnormalities on clinical examination were associated with increasing likelihood of having abnormal findings on TCT (odds ratio [OR] 2.04, 95% confidence interval [CI] 1.21-3.44, P = 0.008) and of requiring an intervention (OR 1.82, 95% CI 1.32-2.51, P <0.001). CONCLUSIONS AND RELEVANCE: RTAs were the most common reported cause of blunt trauma. Atelectasis, pulmonary contusions and pneumothorax were the most common abnormalities identified on TCT, and thoracic drainage was the most utilised intervention. TCT may be useful in identifying cats with normal thoracic physical examination findings that have significant thoracic pathology, and a high number of abnormal findings on thoracic examination should raise suspicion for both minor and major thoracic pathology. The results of this study can be used to assist in selecting appropriate cases for TCT after blunt trauma.

Pneumothorax in a term newborn.

With the advent of surfactant and gentle ventilation, the incidence of neonatal pneumothorax has decreased over the last two decades. Pneumothorax associated with respiratory distress syndrome is more common in preterm infants, but term infants often present with isolated pneumothorax. The use of CPAP or non-invasive respiratory support in the delivery room for a term infant with respiratory distress increases transpulmonary pressures and increases the risk of pneumothorax. Prompt diagnosis with a high index of suspicion, quick evaluation by transillumination, chest X-ray or lung ultrasound is critical. Management includes observation, needle thoracocentesis and if necessary, chest tube placement. This manuscript reviews the incidence, pathogenesis, diagnosis and management of a term infant with isolated pneumothorax, summarizing the combination of established knowledge with new understanding, including data on diagnostic modes such as ultrasound, reviewing preventative measures, and therapeutic interventions such as needle thoracocentesis and a comparison of pigtail vs. straight chest tubes.

Incidental Diagnosis of Left Pneumothorax Using a New Variant of the Lung Point Sign During Cardiac Ultrasound.

BACKGROUND: Pneumothorax is a common issue in the intensive care unit and emergency department, often diagnosed using lung ultrasound. The absence of lung sliding and the presence of the lung point sign are characteristic findings for pneumothorax. We describe a case of left pneumothorax diagnosed incidentally while performing a cardiac ultrasound through a new variant of the lung point sign. CASE REPORT: A 60-year-old patient with a medical history of diabetes, stroke, and right colon cancer underwent urgent surgical treatment for intestinal sub-occlusion. In the intensive care unit, the patient required mechanical ventilation due to shock unresponsive to fluid administration, and hemodynamic monitoring was performed using echocardiography. During systole in an apical four-chamber view, the abrupt vanishing of the heart was observed. When evaluating the tricuspid annular plane systolic excursion (TAPSE) using M-mode, the interposition of the stratosphere sign during mid-systole prevented the visualization of the TAPSE peak. Lung ultrasound revealed the absence of lung sliding and the presence of the lung point sign on the left side of the thorax, confirming the diagnosis of pneumothorax. A chest x-ray study further confirmed the diagnosis, and urgent drainage was performed. The patient showed improvement in hemodynamic and respiratory conditions and was successfully weaned from mechanical ventilation, and eventually discharged home. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: By incorporating the lung ultrasound findings, including this new variant of the lung point sign, into their diagnostic approach to pneumothorax, emergency physicians can promptly initiate appropriate intervention, such as chest tube insertion, leading to improved patient outcomes.

Intrathoracic endometriosis resulting in catamenial pneumothorax.

A woman in her early 40s presented with right-side chest pain radiating to the ipsilateral shoulder coinciding with her menstrual periods. She complained of worsening dysmenorrhoea over the preceding 6 months. Chest radiograph was notable for pneumothorax. Conservative management through hormonal suppression was initially pursued but proved ineffective for preventing recurrence. The patient ultimately underwent video-assisted diagnostic thoracoscopic surgery through robotic approach; intraoperative findings confirmed the presence of endometrial deposits of the diaphragm, confirming the cause of the patient's catamenial pneumothorax. The patient recovered well and was started on a gonadotropin-releasing hormone antagonist 3 weeks following her operation.

Sixty-four-fold data reduction of chest radiographs using a super-resolution convolutional neural network.

OBJECTIVES: To develop and validate a super-resolution (SR) algorithm generating clinically feasible chest radiographs from 64-fold reduced data. METHODS: An SR convolutional neural network was trained to produce original-resolution images (output) from 64-fold reduced images (input) using 128 × 128 patches (n = 127 030). For validation, 112 radiographs-including those with pneumothorax (n = 17), nodules (n = 20), consolidations (n = 18), and ground-glass opacity (GGO; n = 16)-were collected. Three image sets were prepared: the original images and those reconstructed using SR and conventional linear interpolation (LI) using 64-fold reduced data. The mean-squared error (MSE) was calculated to measure similarity between the reconstructed and original images, and image noise was quantified. Three thoracic radiologists evaluated the quality of each image and decided whether any abnormalities were present. RESULTS: The SR-images were more similar to the original images than the LI-reconstructed images (MSE: 9269 ± 1015 vs. 9429 ± 1057; P = .02). The SR-images showed lower measured noise and scored better noise level by three radiologists than both original and LI-reconstructed images (Ps < .01). The radiologists' pooled sensitivity with the SR-reconstructed images was not significantly different compared with the original images for detecting pneumothorax (SR vs. original, 90.2% [46/51] vs. 96.1% [49/51]; P = .19), nodule (90.0% [54/60] vs. 85.0% [51/60]; P = .26), consolidation (100% [54/54] vs. 96.3% [52/54]; P = .50), and GGO (91.7% [44/48] vs. 95.8% [46/48]; P = .69). CONCLUSIONS: SR-reconstructed chest radiographs using 64-fold reduced data showed a lower noise level than the original images, with equivalent sensitivity for detecting major abnormalities. ADVANCES IN KNOWLEDGE: This is the first study applying super-resolution in data reduction of chest radiographs.

Major pneumothorax during pediatric cardiac MRI procedure under general anesthesia: step-by-step analysis and importance of a well-known environment and material.

BACKGROUND: To perform step-by-step analysis of the different factors (material, anesthesia technique, human, and location) that led to major pneumothorax during an infrequent pediatric cardiac MRI and to prevent its occurrence in the future. Anesthesia equipment used in a remote location is often different than those in operating rooms. For magnetic resonance imaging (MRI), ventilation devices and monitors must be compatible with the magnetic fields. During cardiac MRI numerous apneas are required and, visual contact with the patient is limited for clinical evaluation. Anesthesia-related barotrauma and pneumothorax are rare in children and the first symptoms can be masked. CASE PRESENTATION: A 3-year-old boy with atrial septal defect (ASD) and suspicious partial anomalous pulmonary venous return was anesthetized and intubated to perform a follow up with MRI. Sevoflurane maintenance and ventilation were performed using a circular CO2 absorber device, co-axial circuit, and 500 mL pediatric silicone balloon. Apneas were facilitated by Alfentanyl boluses and hyperventilation. A few moderated desaturations occurred during the imaging sequences without hemodynamic changes. At the end of the MRI, facial subcutaneous emphysema was observed by swollen eyelids and crackling snow neck palpation. A complete left pneumothorax was diagnosed by auscultation, sonography examination, and chest radiograph. Pneumo-mediastinum, -pericardium and -peritoneum were present. A chest drain was placed, and the child was extubated and transferred to the pediatric intensive care unit (PICU). Despite the anesthesiologist's belief that PEEP was minimal, critical analysis revealed that PEEP was maintained at a high level throughout anesthesia. After the initial barotrauma, repeated exposure to high pressure led to the diffusion of air from the pleura to subcutaneous tissues and mediastinal and peritoneal cavities. Equipment check revealed a functional circular circuit; however, the plastic adjustable pressure-limiting valve (APL) closed within the last 30° rotation. The balloon was found to be more rigid and demonstrated significantly reduced compliance. CONCLUSIONS: Anesthetists require proficiency is using equipment in non-OR locations and this equipment must be properly maintained and checked for malfunctions. Controlling the human factor risks by implementing checklists, formations, and alarms allows us to reduce errors. The number of pediatric anesthesia performed routinely appeared to be essential for limiting risks and reporting our mistakes will be a benefit for all who care about patients.