Air Dissection Research Articles

Pneumomediastinum as a manifestation of a bronchial carcinoid tumour: a very rare association of two uncommon diseases

A 29-year-old man presented to the emergency department with haemoptysis and thoracic pain. His vital signs and blood tests were normal, except for increased C-reactive protein levels. Fibrolaryngoscopy and esophagogastroduodenoscopy results were negative. Computed Tomography of the chest revealed abundant pneumomediastinum, air dissection along the peribronchovascular sheaths of the left lower lobe and a vegetating lesion completely occluding the distal extremity of the left main bronchus. After complete bronchoscopic excision of the lesion, histological examination revealed a carcinoid tumour not otherwise specified. After hospital discharge, 18F-fluorodeoxyglucose and 68Ga-DOTANOC positron emission tomographies ruled out distant metastases. A sleeve resection of approximately 20 mm of the distal extremity of the left main bronchus and a circumferential anastomosis between the left main bronchus and ipsilateral lobar bronchi were performed. Several bronchoscopic follow-ups did not show anastomotic dehiscence or tumour relapse.

Hamman syndrome with a rare feature of pneumorrhachis – an unusual complication of polysubstance abuse and e-vaping

Hamman syndrome is defined as dissection of air in mediastinum and skin fascia usually due to increased intrathoracic pressure. The air leak tends to make its way into pleural and pericardial layers; however, in rare instances air can also dissect into epidural spaces, regarded as pneumorrhachis. We present a case of a young male with a history of polysubstance abuse and e-vaping, who presented with symptoms of altered mental status. Given the concerning physical examination, a computed tomography of the chest was undertaken, which showed pneumothorax, pneumomediastinum and pneumorrhachis. The patient was closely monitored in the intensive care unit and improved after symptomatic management. The symptoms of pneumorrhachis depend on the volume and location of air in intracranial and intraspinal space. Although asymptomatic in our case, it is crucial for clinicians to be aware that pneumorrhachis with Hamman syndrome can potentially cause neurological deficits and cardiopulmonary arrest in severe cases due to increased intraspinal and intracranial hypertension, emphasising the need for close monitoring.

Rare case of pseudo-pneumoperitoneum as a triad of extensive subcutaneous emphysema and pneumomediastinum as a complication of non-invasive respiratory support

Respiratory support through non-invasive ventilation and high-flow nasal cannula is frequently used in patients with acute respiratory failure as a way to maintain oxygenation without intubation. Although mostly well-tolerated, infrequent but increasingly recognized complications can occur, such as pneumothorax, pneumomediastinum, and subcutaneous emphysema. This likely occurs as a result of alveolar rupture from barotrauma related to ventilatory support and dissection of higher-pressure air along the pulmonary interstitium and into the anatomic cavities of the chest. We present a rare case of pseudo-pneumoperitoneum as a result of non-invasive respiratory support. This occurred as part of a triad of pneumomediastinum and extensive subcutaneous emphysema extending circumferentially around the abdomen and into the scrotum of a hypoxic patient with congestive heart failure and chronic obstructive pulmonary disease exacerbation with pneumonia requiring aggressive respiratory support.

Pathogenesis and Minimally Invasive Management of Subcutaneous Emphysema: A Narrative Literature Review

Subcutaneous emphysema is the result of air infiltrating the subcutaneous and soft tissues. The prevalence of subcutaneous emphysema varies between 0.43% and 2.34%. Subcutaneous emphysema typically results in mild symptoms, poses no significant risk, and does not necessitate specific medical intervention. Pathologies affecting underlying tissues can exhibit greater severity and pose a risk to life. Subcutaneous emphysema is a challenge in terms of how to handle it. The treatment should initiate a focused endeavor to determine the underlying etiology of subcutaneous air dissection. This literature review focuses on subcutaneous emphysema, specifically exploring its pathogenesis and therapy strategies for people with this condition.

Solated Pneumopericardium in a Neonate: A Case Report

Pneumopericardium (PPC) is a rare but life-threatening condition that mostly accompanies air leak syndromes in neonates receiving positive pressure ventilation. PPC results from the rupture of the alveoli and subsequent dissection of air through the tissue planes into the mediastinum, pleura, or pericardial sac. This report describes the case of a term low birth weight neonate born in a peripheral hospital who developed respiratory distress soon after birth. She was transported with manual bag and tube ventilation, and was found to have air leak syndrome in the form of isolated PPC. The neonate was managed conservatively with spontaneous resolution of the PPC.

The Macklin effect in tension pneumomediastinum in a patient with interstitial pneumonia.

Key messageTension pneumomediastinum is a rare complication of interstitial pneumonia. This case shows computed tomography findings of the Macklin effect, in which air dissection along the bronchovascular interstitium caused by alveolar rupture leads to pneumomediastinum.

Reverse Macklin effect.

The Macklin effect is associated with alveolar rupture causing a centripetal spread of air along the peribronchovascular interstitial sheath leading to pneumomediastinum, usually seen in ventilator-related barotrauma or blunt chest trauma. We are presenting a peculiar case of iatrogenic (post-intubational) tracheal injury with massive subcutaneous emphysema and pneumomediastinum, in whom, we suspect that the primary tracheal injury and pneumomediastinum led to dissection of air along the peribronchovascular interstitium, culminating in atelectasis of lung due to compression of the distal-most airways, with no primary parenchymal abnormality. This supposed "reversal" of pathophysiological sequence of the Macklin effect makes it a unique finding.

VAPING-ASSOCIATED ASTHMA EXACERBATION PRESENTING AS SPONTANEOUS PNEUMOMEDIASTINUM

TOPIC: Obstructive Lung Diseases TYPE: Fellow Case Reports INTRODUCTION: Pneumomediastinum is usually caused by a dissection of air from alveolar-pleural communications or the introduction of air from other intrathoracic (e.g., esophageal, tracheal, bronchial) or extrathoracic sources. We describe a case of Vaping-associated asthma exacerbation presenting as spontaneous pneumomediastinum (SPM). CASE PRESENTATION: The patient is a 19-year-old male with high functioning cerebral palsy, epilepsy, daily inhalational nicotine, and marijuana use presented with dyspnea, pleuritic chest, and right neck pain. He had presented to the emergency department two days prior to this admission with dyspnea and wheezing. At that time, he was empirically treated for asthma exacerbation with albuterol nebulization and IV steroids with improvement in symptoms despite no prior formal diagnosis of asthma. Upon discharge, he started using an electronic nicotine vape in an attempt to quit smoking cigarettes. He continued to have dyspnea and spontaneously developed new chest and neck pain, which prompted him to revisit the ER for further evaluation. He claimed that he did not take his medications as prescribed on discharge. His chest radiography showed hyperinflated lungs with new subcutaneous air in the right neck compared to previous imaging. He denied any violent cough, vomiting, or retching prior to arrival. At presentation, he was afebrile, tachycardia(108 bpm), normal respiratory rate(20), and had an oxygen saturation of 94% on room air. He had nasal tone, bilateral diffuse expiratory wheezing, and crackles on palpation on the upper chest and neck. His initial blood gas showed hypercapnia, prompting ICU admission for closer monitoring. His CT chest with oral contrast showed subcutaneous emphysema in the neck and pneumomediastinum with no extravasation of contrast from the esophagus. His lab work showed positive rhinovirus PCR, elevated eosinophil levels, IgE levels, and a positive RAST panel for dust mites. He was treated with supplemental oxygen, bronchodilators, and steroids with improvement in clinical and imaging findings. Spirometry prior to discharge showed airflow obstruction consistent with the working diagnosis of asthma. He was discharged on ICS/LABA inhaler therapy with PRN albuterol for shortness of breath. DISCUSSION: E-Vaping, even for purposes of smoking cessation, can be detrimental during an asthma exacerbation. We believe the combination of air trapping due to bronchoconstriction in the setting of asthma exacerbation and rapid and large volume inhalation of an electronic cigarette can lead to an abrupt increase in the intra-alveolar pressure resulting in alveolar rupture. This released alveolar air dissects centripetally through the pulmonary interstitium along the bronchovascular sheaths toward the pulmonary hila into the mediastinum, causing SPM. CONCLUSIONS: The learning objective is vaping can increase the risk of SPM in the setting of asthma exacerbation. REFERENCE #1: S. Faruqi, R. Varma, M.A. Greenstone & J.A. Kastelik (2009) Spontaneous Pneumomediastinum: A Rare Complication of Bronchial Asthma, Journal of Asthma, 46:9, 969-971, DOI: 10.3109/02770900903215635 DISCLOSURES: No relevant relationships by Rajesh Kunadharaju, source=Web Response No relevant relationships by Alberto Monegro, source=Web Response No relevant relationships by Ryan Salemme, source=Web Response No relevant relationships by Kathyayini Tappeta, source=Web Response

VAPING-INDUCED ALVEOLAR RUPTURE LEADING TO PNEUMOMEDIASTINUM IN A YOUNG FEMALE

TOPIC: Disorders of the Mediastinum TYPE: Medical Student/Resident Case Reports INTRODUCTION: Electronic cigarette use or "vaping" has been on the rise in America over the last decade. Literature shows that approximately 8.1 million Americans admitted to vaping in 2018. Vaping is when one inhales and exhales an aerosolized solution (Vaper) through a cigarette-like electrical device. Some chemicals found in vapers have been linked to disease processes. While using E-cigarettes, the participant inhales a large amount of vaper, exaggerating the Valsalva maneuver, subsequently increasing intra-thoracic pressure. This increase in thoracic pressure places the participant at risk for spontaneous pneumomediastinum. We present a case of a 19-year-old female diagnosed with spontaneous pneumomediastinum. The only risk factor, the use of electric cigarettes. CASE PRESENTATION: A 19-year-old female with a history of type 1 diabetes mellitus and vape dependence presents with a 3-day history of abdominal pain, chest pain, and retching. She admitted to vaping daily for one year before the presentation. Physical examination revealed no evidence of respiratory distress along with slight crepitus tracheal area at the level above the clavicle. She was found to be in diabetic ketoacidosis (DKA), which was also treated. She continued to have epigastric burning along with chest pain. For this reason, computed tomography (CT) of the chest was performed and showed pneumomediastinum. She did not meet the Pittsburg criteria for esophageal rupture. Barium swallow eventually ruled out esophageal rupture. The pneumomediastinum likely occurred secondary to vape-induced alveolar rupture. She was treated with supplemental oxygen, and serial chest radiograph showed gradual resolution of pneumomediastinum. DISCUSSION: Laennec first described pneumomediastinum (PM) in 1819 as a consequence of traumatic injury. The clinical presentation could be very vague, ranging from classic chest pain to unspecific symptoms, which lead to delayed diagnosis. The pathophysiology of can be described by the Macklin effect as follows: (a) alveolar rupture, (b) air dissection along the bronchovascular sheath, and (c) free air reaching the mediastinum. Chest radiography, the standard diagnostic procedure, diagnosis can be confirmed by chest computed tomography scan. Once the diagnosis is approved, the patient should be admitted for monitoring and treatment consisting of avoidance of the trigger factors, oxygen, and bed rest. CONCLUSIONS: Spontaneous pneumomediastinum secondary to vaping is on the rise. The diagnosis of vaping-induced lung injury continues to be a dilemma among physicians. A high index of suspicion is necessary for early detection and treatment. Although most cases are benign, it will be prudent for health care providers to actively query patients about their use and educate patients on their potential severe side effects. REFERENCE #1: Pneumomediastinum: Practice Essentials, Pathophysiology, Epidemiology. Accessed April 28, 2021. https://emedicine.medscape.com/article/1003409-overview REFERENCE #2: Marasco RD, Loizzi D, Ard NP, Fatone FN, Sollitto F. Spontaneous Pneumomediastinum After Electronic Cigarette Use. Ann Thorac Surg. 2018;105:e269-e271. doi:10.1016/j.athoracsur.2017.12.037 REFERENCE #3: Panacek EA, Singer AJ, Sherman BW, Prescott A, Rutherford WF. Spontaneous pneumomediastinum: Clinical and natural history. Ann Emerg Med. 1992;21(10):1222-1227. doi:10.1016/S0196-0644(05)81750-0 DISCLOSURES: No relevant relationships by Esiemoghie Akhigbe, source=Web Response No relevant relationships by Ebubechukwu Ezeh, source=Web Response No relevant relationships by Mackenzie Hamilton, source=Web Response No relevant relationships by Mohamed Suliman, source=Web Response

Decrease of microbial contamination by application of routinely glycerol and phenol solution on human cadavers

Human cadaver is imperative learning material for medical students. The cadavers expose to microbial contamination every time anatomists work with them. The microorganisms found in preparations’ cadavers could be pathogenic. Although the cadaver has supported a preservation method but does not inhibit microbial germination. The purposes of this study were evaluation the use of the routine solution to decrease potential contamination. Samples were collected air dissection hall and cadavers' sections after drying the cadavers, and after use of routinely glycerin and phenol solution (1.5 g phenol in 100 cc glycerol), inoculated on eosin methylene blue agar (EMB), blood agar (BA), Sabouraud dextrose agar (SDA), and SDA with the addition of chloramphenicol (50 mg/l in ethanol solution) (SC), in a Petri dish and incubated at 25 °C and 37 °C. After 3-5 days, the morphology was studied macroscopically and microscopically. We found Sporothrix schenckii ; Streptomyces , Bacillus subtilis and Aspergillus flavus , Geotrichum candidum , on the samples of dryness cadavers and air dissection hall, respectively. But fungus and bacteria contamination was decreased after the use of glycerin and phenol solution. Based on the results of this study, it is suggested that glycerol and phenol solution can be used at least once a week to reduce microbial contamination and prevent the spread of the disease from the cadavers to students and professors.

A CASE OF HAMMAN SYNDROME AND EPIDURAL PNEUMORRHACHIS IN THE SETTING OF METHAMPHETAMINE ABUSE

SESSION TITLE: Late-breaking Abstract Posters SESSION TYPE: Original Investigation Posters PRESENTED ON: October 18-21, 2020 PURPOSE: Hamman’s syndrome can rarely coexist with pneumorrhachis when spontaneous collection of air in the mediastinum traverses through the fascial planes into the spinal canal. We report an unusual circumstance of Hamman’s syndrome developing into a pneumorrhachis in a patient after inhaled methamphetamine abuse. METHODS: A 20-year-old male presented after inhaling methamphetamine and developed severe bouts of cough and dyspnea. He also complained of neck pain that was sudden in onset and worsened with flexion and subsequent chest pain. Vitals on presentation were stable and swelling of his neck with subcutaneous crepitations in the jaw and chest were found on examination. Heart sounds were distant, but audible. Urine toxicology was positive for amphetamines. A chest x-ray revealed air around the upper mediastinum as well as periclavicular regions. A computer tomography (CT) scan showed the presence of subcutaneous emphysema and pneumomediastinum along with air column noted in the spinal canal, establishing a diagnosis of Hamman’s syndrome with pneumorrhachis. A gastrograffin study did not reveal esophageal tears or ruptures. During his admission, he was conservatively managed with serial chest x-rays showing gradual improvement in his subcutaneous emphysema. RESULTS: Hamman’s syndrome includes both subcutaneous emphysema and spontaneous pneumomediastinum (SPM). Risk factors such as coughing, vomiting and scuba diving, as well as systemic conditions such as asthma and cystic fibrosis can lead to an increase in intrathoracic pressure and alveolar rupture with dissection of air in the interstitial space, bronchovascular sheaths and subsequently to the mediastinum, also known as Macklin effect. Methamphetamine use can increase inflammatory markers such as tumor necrosis factor (TNF) alpha and IL-6, potentiating alveolar damage and risk of SPM. The combination of Hamman’s syndrome with pneumorrhachis is uncommon and occurs due to the passage of air between fascial planes from the posterior mediastinum into the neural foramina and epidural space. Examination of the patient includes auscultatory findings of pulmonary crackles synchronized with the heart sounds, known as Hamman’s sign. CT scan is considered as the gold standard imaging modality for diagnosis and anatomic localization. Treatment for uncomplicated SPM is supportive including analgesia, rest, treatment of underlying lung disease and avoidance of maneuvers that increase alveolar pressure. Surgical management is reserved for those who develop pneumorrhachis that is iatrogenic in nature or in the presence of complications such as hemodynamic instability and esophageal ruptures. CONCLUSIONS: We describe a unique case of symptomatic Hamman's syndrome and epidural pneumorrhachis secondary to methamphetamine use. CLINICAL IMPLICATIONS: Although uncommon, both these entities can be life-threatening and requires prompt evaluation and treatment. DISCLOSURES: No relevant relationships by Adhiraj Bhattacharya, source=Web Response No relevant relationships by Gahyun Gim, source=Web Response no disclosure on file for David Lee; No relevant relationships by Gemini Yesodharan, source=Web Response

PNEUMOMEDIASTINUM IN PATIENTS WITH SUBSTANCE ABUSE: A CASE SERIES

SESSION TITLE: Medical Student/Resident Disorders of the Mediastinum Posters SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: Pneumomediastinum (PM) is the presence of air in the mediastinum. PM is associated with asthma exacerbation, severe cough or vomiting, and other activities associated with breathing maneuvers. Although the majority of cases could be managed conservatively, PM could be potentially fatal if it progresses to malignant PM, which requires thoracotomy or video-assisted thoracoscopy for management. Therefore closely monitoring the patient is necessary. CASE PRESENTATION: Case 1: A 20-year-old male who uses marijuana, was admitted due to 3 days of intractable nausea, vomiting, and right-side anterior pleuritic chest pain. Vital signs were normal. Abdominal exam showed epigastric tenderness, without guarding or rebound. Laboratory showed leukocytosis. CXR revealed subcutaneous emphysema in the left supraclavicular region without PM. Chest CT showed free air in posterior mediastinum (Figure 1). Evaluation did not demonstrate esophageal rupture. He was treated conservatively. The symptoms improved and he was discharged. Case 2: A 20-year-old male with marijuana use for 4 years presented with shortness of breath, intractable vomiting, bloody emesis, chest pain, and shortness of breath. Vital signs were normal. Examination showed subcutaneous emphysema along anterior chest up to neck, with clear and equal breath sound. Laboratory showed leukocytosis. CXR and chest CT showed subcutaneous emphysema and PM (Figure 2). With investigation, there was no evidence of esophageal rupture. The symptoms resolved and he was discharged. Case 3: An 18-year-old male with type 1 diabetes mellitus and polysubstance abuse history presented with sudden severe right-side chest pain, mild shortness of breath, and nausea over 2 days. He admitted smoking methamphetamine prior to his symptoms. Vital signs were normal. Examination was notable for moderate dehydration. Laboratory revealed leukocytosis, elevated blood glucose, and wide-anion gap metabolic acidosis with elevated acetone. Urine drug screen was positive for methamphetamine. CXR showed PM and left supraclavicular subcutaneous emphysema. Chest CT showed isolated PM (Figure 3). The patient was given pain medication and was treated for DKA. He improved and was discharged. DISCUSSION: PM among substance users is believed to be a result from barotrauma during breathing maneuvers. An increase in alveolar pressure with development of a pressure gradient between alveoli and surrounding blood vessels leads to increased alveolar pressure, rupture of the alveolar septa, collapse of the adjacent vascular structures, and air dissection around the peribronchial and perivascular sheaths. Conservative management is sufficient for the majority of PM. CONCLUSIONS: Pneumomediastinum is a rare condition that could be potentially life threatening. PM should be considered in patients with history of inhaled drug use who develop sudden chest pain. Reference #1: Kouritas VK, Papagiannopoulos K, Lazaridis G, et al. Pneumomediastinum. J Thorac Dis 2015;7(Suppl 1):S44–S49. Reference #2: Weiss ZF, Gore S, Foderaro A. Pneumomediastinum in marijuana users: a retrospective review of 14 cases. BMJ Open Respir Res. 2019 Feb 12;6(1):e000391. doi: 10.1136/bmjresp-2018-000391. Reference #3: Miller WE, Spiekerman RE, Hepper NG. . Pneumomediastinum resulting from performing Valsalva maneuvers during marijuana smoking. Chest. 1972 Aug;62(2):233-4. DISCLOSURES: No relevant relationships by Amr Ismail, source=Web Response No relevant relationships by Passisd Laoveeravat, source=Web Response No relevant relationships by Arunee Motes, source=Web Response No relevant relationships by Victor Test, source=Web Response

S1997 Spontaneous Pneumomediastinum Secondary to Cannabinoid Hyperemesis Syndrome

INTRODUCTION: Marijuana use has been infrequently identified as a potential risk factor for the development of spontaneous pneumomediastinum, a rare condition characterized by free air in the mediastinum not preceded by medical or surgical trauma. We present the case of cannabinoid hyperemesis syndrome causing spontaneous pneumomediastinum. CASE DESCRIPTION/METHODS: A 23-year-old female with a history of cannabinoid hyperemesis syndrome presented to the emergency room with a 3-day history of chest pain associated with nausea and multiple episodes of vomiting. She confirmed a three-year history of daily inhaled marijuana use. A CT Chest revealed extensive pneumomediastinum with air tracking along the left hilum/bronchovascular sheath of an unclear source with no radiographic evidence of chest trauma. The patient was admitted to the intensive care unit for continued management. Subsequent water-soluble contrast esophageal revealed findings consistent with pneumomediastinum and no evidence of esophageal perforation, hence Boerhaave’s syndrome was excluded. Given her recurring cyclic vomiting in the setting of cannabis the patient was diagnosed with cannabinoid hyperemesis syndrome (CHS) with spontaneous pneumomediastinum. The patient was managed conservatively, with complete recovery and extensively counseled on cannabis cessation. DISCUSSION: Inhaled marijuana use has been infrequently identified as a potential risk factor for the development of spontaneous pneumomediastinum. Spontaneous pneumomediastinum is a rare clinical entity defined as the presence of free air within the mediastinal structures in the absence of thoracic trauma, surgery, or medical procedure. It is a self-limiting condition resulting from alveolar rupture secondary to an acute increase in intrathoracic pressure subsequently leading to dissection of air along the bronchovascular sheath towards the mediastinum. The hypothesized pathophysiology of marijuana related pneumomediastinum is barotrauma occurring during breathing movements. SPM is managed conservatively with analgesia and treatment of the underlying etiology. Long term prognosis depends on the etiology of the SPM and involves lifestyle modification especially in the setting CHS. Diagnosis of a SPM can often be overlooked as its presenting symptoms remains non-specific. A comprehensive history should be obtained including a detailed history of tobacco and cannabinoid use in patients with intractable nausea and vomiting with a low threshold for chest imaging.Image 1.: Air within the mediastinal structures with no evidence of perforation.Image 2.: Water-soluble contrast esophagram with no evidence of contrast extravasation into the mediastinum.

Esophageal pneumatosis: a pictorial review.

Gastrointestinal pneumatosis has been reported from the esophagus to the rectum, with most cases involving the small bowel, stomach, or colon. Esophageal pneumatosis is rare, with only a small number of case reports described in the literature, although it is likely underreported. Esophageal pneumatosis may be idiopathic or secondary to a specific underlying cause. Mechanisms of esophageal pneumatosis include increased intraluminal pressure, mucosal disruption, and dissection of air from an extraesophageal source. Depending on the underlying cause, esophageal pneumatosis is usually benign although it may be indicative of a life threatening condition. Esophageal pneumatosis is typically detected with CT, although it may be evident during direct visualization with endoscopy. In this article, we review the etiologies and imaging appearances of esophageal pneumatosis.

P40 Spontaneous pneumomediastinum in mixed connective tissue disease

Abstract Background Spontaneous pneumomediastinum refers to dissection of free air from the airways on lung parenchyma into the mediastinal structures without any antecedent thoracic trauma or surgical intervention. Pneumomediastinum has been described as a rare complication of connective tissue disease, most commonly in dermatomyositis and polymyositis. Here we report 2 cases of mixed connective tissue disease (MCTD) who developed pneumomediastinum. Methods The first case was a 76 year old male undergoing assessment for MCTD. During assessment, he was found to have bi-basal crepitations without any obvious respiratory symptom. He was on steroids for last 4 weeks for proteinuria. His High- resolution CT scan (HRCT) showed pneumomediastinum with evidence of Interstitial lung disease (ILD) without any complication. He was monitored closely and his pneumomediastinum resolved without any intervention. The second case was a 49 year old female with known MCTD & was on steroids for 5 months. She was admitted to the hospital with weight loss and dysphagia. This was a long hospital stay during which she developed pneumomediastinum with pneumothorax and surgical emphysema around the neck. She required ICU admission and was transferred to cardiothoracic centre where she underwent bronchoscopy, VATS inspection and required chest drains. Results In both cases there were similarities where both patients with MCTD were on variable duration of steroids & had ILD. They then developed pneumomediastinum with surgical emphysema, however their course was quite contrasting where the first case was relatively benign & resolved without any intervention while the second one required long ITU stay with multiple complications and interventions. Conclusion Spontaneous pneumomediastinum is an uncommon manifestation of CTD and only few cases have been reported with MCTD. Although spontaneous mediastinum seems to be associated with a relatively benign short-term course, one should be wary of complications and have low threshold for investigating for any new lung symptoms in context of CTD. It is uncertain whether severity of MCTD or duration of steroids use impacts the progress of spontaneous pneumomediastinum as there are very limited number of cases. Disclosures F. Hasan None. V. Kumar None. S. Silburn None. R. Thomson None.

Air dissection of the spaces of the head and neck: A new teaching and dissection method

Our goal was to evaluate a new air dissection technique for the spaces of the head and neck using fresh-frozen cadavers. Eight sides from four fresh-frozen Caucasian cadavers were used in this study. Compressed air was initially placed into the pterygomandibular space while simultaneously observing the spaces of the head and neck. Subsequently, the pterygomandibular space on the contralateral side of the specimen was insufflated and observations made. For these methods, simultaneous observation of mediastina and lungs was made using intrathoracic endoscopy. On all sides, the buccal, submental, sublingual, parotid, parapharyngeal, and retropharyngeal spaces were insufflated on both ipsilateral and contralateral sides. Deviation of the larynx and trachea was observed externally and deviation of the mediastinum and lungs via intrathoracic endoscopy. We introduced air dissection into spaces of the head and neck. This new technique might help students, teachers, dentists, medical doctors, and other healthcare providers to better understand the three-dimensional anatomy of the spaces of the head and neck and their communicating pathways. Clin. Anat. 33:207-213, 2020. © 2019 Wiley Periodicals, Inc.

Posttraumatic Pneumosialodenitis of the Submandibular Gland

There are multiple etiologies for facial subcutaneous emphysema, including facial trauma, dissection of air along facial planes from a pneumomediastinum, infection, and entry of air through defects in teeth due to decay, trauma, or dental procedure. In addition, air can be forced through lacerations of the oral or pharyngeal mucosa by increased intraoral pressure. An infrequently reported cause of subcutaneous emphysema is autoinsufflation of the parotid duct with extravasation of air into the surrounding tissue. In this report, the authors present a 14-year-old patient treated at the Department of Oral and Maxillofacial Surgery of the Hospital Escuela Universitario due to an increase in size in the buccal region and left masseterine space of 2 months of evolution. Presenting with a sudden evolution, without any possible explanation, which caused displacement of adjacent structures without damage to the bone or surrounding tissues. After a series of echographic and tomographic studies, it showed that inside the submandibular gland there was a hypodense image with gas density (-1100 UH) expanding the gland and its respective excretory duct.

Pre-Descemet’s Endothelial Keratoplasty (PDEK): Learning Curve in the First Brazilian Cases

Purpose: To describe the learning curve of pre-descemet endothelial keratoplasty (PDEK) and the intraoperatory findings of the first 5 cases performed at Federal University of Sao Paulo. Methods: Five PDEK procedures were performed by the same surgeons; four cases used pneumodissection and one case used reverse hydro-bubble technique to obtain the donor graft. All cases were recorded and the following intraoperative variables were measured: type of bubble obtained, button size used and time of opening and centralization of the graft in the recipient anterior chamber. Results: Type-1 Big Bubble (BB) was achieved in three of the four cases that air dissection was used. In the fourth case of pneumodissection, there was simultaneous formation of type-1 and type-2 BB. When balanced saline solution was used for dissection, type-2 BB was obtained. Every time type-2 BB was formed, the procedure was then converted to Descemet Membrane Endothelial Keratoplasty (DMEK). When only type-1 BB was achieved, the PDEK was uneventful with an easier, manipulation of the tissue and a quicker opening in the recipient anterior chamber. Namely, grafts that included pre-Descemet’s layer were less elastic and less curled. The graft size used varied from 7.50 to 7.75mm. Conclusion: PDEK is a recent technique of endothelial keratoplasty. Early outcomes suggest potential advantages in the learning curve over the prior procedures, especially by the facilitated manipulation of PDEK graft in the anterior chamber. Although results with this technique seem promising, the potential advantages need to be confirmed with long-term postoperative follow-up.

Spontaneous pneumomediastinum, Hamman's syndrome, with diabetic ketoacidosis

A 34-year-old, fit Caucasian woman with no previous medical or surgical illness, presented to A&E with sudden onset of several episodes of projectile vomiting unrelieved by simple measures and associated with chest discomfort, breathlessness and headache. Initial evaluations showed high blood glucose 26 mmol/L, blood pressure 110/65 mmHg, pulse 112/min regular, respiratory rate 26/min, SPO2 100% on room air and temperature 37 °C; she was found to have blood ketones of 4.2 mmol/L, metabolic acidosis with pH 7.29, HCO3 11, CO2 4.3, O2 11.3, base excess −12, and lactate 1.2. She was diagnosed with diabetic ketoacidosis (DKA) and was managed as per local standard DKA protocol. Pneumomediastinum (Figure 1) was detected on a chest X-ray which was performed routinely as she complained of chest discomfort. ECG showed sinus tachycardia with no ST-T changes. After discussion with chest physicians and radiologists, CT imaging of the chest was done which confirmed pneumomedia­stinum. Further oesophageal swallow with water-soluble contrast CT was done with the advice of cardiothoracic surgeons and this ruled out oesophageal rupture (Boerhaave's syndrome). Gastro­enterologists were consulted to rule out oesophageal injury/Mallory-Weiss tear, due to her acute presentation of projectile vomiting. She had oesophagogastroduodenoscopy (OGD) and was completely normal. Her chest symptoms resolved with DKA treatment and did not require any further intervention. Pneumomediastinum (air in the mediastinum) was first described by Laennec in thoracic trauma patients in 1819.1 Hamman described spontaneous pneumomediastinum as a different entity in 1939.2 Subsequently, this entity was coined ‘Hamman's syndrome’. Pneumomediastinum may result from many factors such as direct chest trauma, oesophageal rupture or barotrauma. Spontaneous or primary pneumomediastinum occurs due to rupture of alveoli when there is an increase in the intrapleural volume with a dramatic increase in intrapleural pressure due to sneezing, coughing, vomiting and Valsalva manoeuvres.3 The incidence of this complication in diabetes is rarely reported. In DKA, hyperventilation due to acidosis and severe vomiting due to ketosis cause changes in the intra-alveolar pressure gradient in the lungs. The rise in the intra-alveolar pressure leads to rupture of alveoli and subsequently dissection of air escaping alongside the perivascular sheaths into the mediastinum.4 Air collection can develop at different anatomical sites depending on the site of alveolar rupture and present in different ways. Sub-pleural alveolar rupture causes pneumothorax and subcutaneous emphysema. Rupture seen adjacent to bronchovascular sheaths causes pneumomediastinum and/or pneumopericardium. Ruptured alveolar gas from posterior mediastinum can pass through the intervertebral foramina into the epidural space causing epidural pneumatosis.5 Chest pain/discomfort is the common presenting symptom in pneumomediastinum. Other symptoms include mild dyspnoea, odynophagia, palpitations, anxiety, subcutaneous emphysema etc depending on the site of air collection. Clinical signs depend on the site of air leak. In pneumomediastinum, a bubbling or crackling sound in the thorax heard on auscultation with cardiac systolic sounds is named ‘Hamman's sign’.6 Diagnostic investigation depends on the clinical presentation and differential diagnosis. Lateral view chest X-ray is the initial test but CT thorax is the gold standard as it can also rule out mediastinitis or oesophageal rupture.7 Oesophagogram can be used if Boerhaave's syndrome is suspected and the patient is alert. However, OGD or CT thorax can be considered if the patient is comatose. It is always necessary to avoid endoscopy until perforation is ruled out.8 Spontaneous pneumomediastinum in DKA is a benign condition and treatment directed towards pneumomediastinum per se is unnecessary unless the patient develops tension pneumothorax. However, correction of metabolic abnormality due to DKA is crucial and pneumomediastinum resolves on its own. Hamman's syndrome can also occur in pregnant diabetic patients presenting with DKA. Close observation is essential and appropriate surgical intervention may be needed depending on the presentation. If found during labour, it is crucial to avoid hypoxia and hence fetal monitoring is imperative. It is suggested that shortening the second stage of labour with instrumental delivery is essential to prevent increased mediastinal pressure. If caesarean section is essential, an epidural needs to be considered and general anaesthesia avoided.9 Awareness of this complication of DKA could have avoided unnecessary investigations in our patient who was very stable. She received treatment for DKA as per the DKA protocol and her chest symptoms resolved within 24–48 hours. She was discharged home with diabetes management. References are available at www.practicaldiabetes.com.

A Case Of Pneumomediastinum with Subcutaneous Emphysema in a Patient of Interstitial Lung Disease

Pneumomediastinum that occurs because of rupture of alveoli and dissection of air along the fascial planes of the tracheobronchial tree is a rare complication of interstitial lung disease (ILD). Diagnosed by CAT scan, it is usually a self-limiting condition managed conservatively with supportive care and oxygen therapy. We present a rare case of pneumomediastinum with subcutaneous emphysema in a patient of ILD.