Pneumothorax: A Review

Improved detection of air-filled lesions using computed tomography in dogs with recurrent spontaneous pneumothorax through reduction of pulmonary atelectasis via positive pressure ventilation

Introduction

Spontaneous pneumothorax in dogs is predominantly caused by the rupture of air-filled lesions, such as bullae or blebs. The efficacy of Computed Tomography (CT) in detecting these lesions has been deemed limited due to its reportedly low sensitivity. This retrospective, cross-sectional study investigates the utility of CT in eight dogs diagnosed with recurrent pneumothorax, all of which had surgical confirmation of the cause of the pneumothorax.

Materials and methods

Thoracic radiographs were obtained before and the day following the CT studies. Initially, a CT study was conducted without positive pressure ventilation (pre-PPV CT). Subsequent CT studies were performed post-evacuation of pneumothorax and with positive pressure ventilation of 15 cmH2O until lung atelectasis was resolved (post-PPV CT). The pre-PPV CT and post-PPV CT images were anonymized and reviewed by two board-certified radiologists. The presence and morphology of air-filled lesions were evaluated on all images. Surgical findings were recorded and compared to the CT findings.

Results

Air-filled lesions were detected in 5 out of 8 dogs in the pre-PPV CT studies and in all 8 dogs in the post-PPV CT studies. The CT findings of air-filled lesions were consistent with surgical findings. None of the dogs showed increased severity of pneumothorax in radiographs taken the day following the CT studies.

Discussions

The study concludes that the resolution of lung atelectasis by evacuation of pneumothorax and positive pressure ventilation during CT studies is feasible and enhances the detection of air-filled lesions in dogs with recurrent spontaneous pneumothorax. This could potentially aid in improving surgical planning.

Thoracic CT incidental pulmonary bullae in dogs: Characterization, interobserver variability, and general anesthesia risks

Ruptures of pulmonary blebs and bullae are the most common cause of spontaneous pneumothorax in dogs. Incidental bullae/blebs have been documented in otherwise healthy people, however information for veterinary patients is currently lacking. Objectives of this retrospective, observer agreement, analytical study were to characterize incidental bullae in thoracic CT studies of dogs, assess interobserver variability for characterizing the bullae, and assess anesthesia risks. Inclusion criteria were dogs presenting for non-pneumothorax related reasons that had a thoracic CT at a single specialty and emergency hospital from 2012 to 2021 and had a bulla listed in the CT report. Medical records for dogs meeting inclusion criteria were reviewed to collect data on signalment, weight, total number of general anesthesia procedures 2 years prior and 2 years following the CT scan, and adverse anesthesia events. In addition, the CT images were reviewed by three American College of Veterinary Radiology-certified veterinary radiologists to collect data on the location, size, number of bullae and thickness of the bulla wall. A total of 1119 dogs met initial inclusion criteria and 74 dogs were included in analyses. There was no sex predilection for incidental pulmonary bullae. Bullae were more commonly found in older (median age 11.3 years), large breed dogs (median weight 20.7 kg). A solitary bulla of less than 1 cm was the most common finding with no apparent predilection for a particular lung lobe. There was strong correlation among the three radiologists for bulla location, size, and number, but weak correlations for bulla wall thickness. No adverse anesthesia events were found following CT anesthesia or following repetitive anesthesia procedures.

Autologous blood pleurodesis for surgical pneumothorax and outcome with multimodal cancer treatment in a dog with primary pulmonary mast cell tumor

A dog underwent lung lobectomy for removal of a mass. Histopathology was consistent with narrow resection of a mast cell tumor. Postoperative pneumothorax was successfully treated using autologous blood pleurodesis. Progression of disease despite adjunctive treatment with several chemotherapetutic agents and radiation therapy resulted in euthanasia approximately 4 months postoperatively.

Suspected Primary Spontaneous Asymptomatic Pneumothorax in a Cat

Spontaneous pneumothorax (SPT) is a documented emergency of the respiratory tract condition classified as either primary or secondary based on the presence of underlying pulmonary conditions. All reported SPT in the feline literature are evaluated for respiratory clinical signs. Primary SPT without underlying pathology or without clinical signs is not reported in cats. This case report describes a 10-year-old domestic longhair cat that was referred for evaluation of chronic lethargy with severe azotemia and placement of a subcutaneous ureteral bypass (SUB) system. Prior to presentation, the cat was diagnosed with renal insufficiency and treated medically with no resolution. Clinical examination under sedation revealed right-sided renomegaly. Thoracic radiographs revealed gas in the caudodorsal pleural space and concurrent pulmonary atelectasis. No respiratory clinical signs were present. Thoracic CT showed two pulmonary bullae, one located in the right caudal lung lobe and one in the cranial segment of the left cranial lung lobe. Abdominal ultrasound showed a right-sided ureteral obstruction. Medical management was elected for the spontaneous pneumothorax. A SUB was placed to address the ureteral obstruction; no complications were noted during recovery. The cat was free of clinical signs of respiratory disease after a follow-up time of nine months. This is the first reported case of a cat diagnosed with a nonclinical suspected primary spontaneous pneumothorax with no concurrent predisposing pulmonary pathology.

Spontaneous pneumothorax in German Shorthair Pointer due to penetration of a grass awn

This case report describes an incident of pneumothorax in 4-month old male German Shorthaired Pointer caused by a grass awn. The patient was brought to the Small Animal Clinic of the Faculty of Veterinary Medicine at Trakia University, Stara Zagora, Bulgaria with respiratory distress and anxiety. Tachypnea, cyanotic mucous membranes and tachycardia were observed during physical examination. Abnormal collection of air in the pleural space between the lung and the chest was observed radiographically. A diagnosis of primary spontaneous closed pneumothorax was made based on these findings. Later pathoanatomical findings showed the presence of the grass awn that had penetrated through the skin.

Bio-inspired green light crosslinked alginate-heparin hydrogels support HUVEC tube formation

Alginate is a polysaccharide which forms hydrogels via ionic and/or covalent crosslinking. The goal was to develop a material with suitable, physiologically relevant mechanical properties and biological impact for use in wound treatment. To determine if the novel material can initiate tube formation on its own, without the dependance on the addition of growth factors, heparin and/or arginyl-glycyl-aspartic acid (RGD) was covalently conjugated onto the alginate backbone. Herein, cell adhesion motifs and bioactive functional groups were incorporated covalently within alginate hydrogels to study the: 1) impact of crosslinked heparin on tubular network formation, 2) impact of RGD conjugation, and the 3) biological effect of vascular endothelial growth factor (VEGF) loading on cellular response. We investigated the structure-properties-function relationship and determined the viscoelastic and burst properties of the hydrogels most applicable for use as a healing cell and tissue adhesive material. Methacrylation of alginate and heparin hydroxyl groups respectively enabled free-radical covalent inter- and intra-molecular photo-crosslinking when exposed to visible green light in the presence of photo-initiators; the shear moduli indicate mechanical properties comparable to clinical standards. RGD was conjugated via carbodiimide chemistry at the alginate carboxyl groups. The adhesive and mechanical properties of alginate and alginate-heparin hydrogels were determined via burst pressure testing and rheology. Higher burst pressure and material failure at rupture imply physical tissue adhesion, advantageous for a tissue sealant healing material. After hydrogel formation, human umbilical vein endothelial cells (HUVECs) were seeded onto the alginate-based hydrogels; cytotoxicity, total protein content, and tubular network formation were assessed. Burst pressure results indicate that the cell responsive hydrogels adhere to collagen substrates and exhibit increased strength under high pressures. Furthermore, the results show that the green light crosslinked alginate-heparin maintained cell adhesion and promoted tubular formation.

Spontaneous Pneumothorax: Pathophysiology, Clinical Presentation and Diagnosis

Spontaneous pneumothorax, which may have an acute or insidious onset in dogs and cats, results in respiratory difficulty and has the potential to be life threatening.^1-3 Dogs commonly develop spontaneous pneumothorax due to bullae or blebs, while cats typically have underlying inflammatory disease, like feline allergic airway disease. Urgent therapeutic intervention is essential in animals with respiratory distress. The recommended therapeutic strategies are typically different in each of these species due to underlying etiology. The first part of this review article will focus on physiology, clinical presentation, and diagnosis of spontaneous pneumothorax in dogs and cats. Advances in diagnostics, especially the recent utility of point of care ultrasound, will be discussed. The second part of the series will provide an overview of therapeutic options and management of patients with spontaneous pneumothorax, as well as information on prognosis.

Treatment and outcome of spontaneous pneumothorax secondary to suspected migrating vegetal foreign body in 37 dogs

BACKGROUND

The aim of this study is to describe surgical findings, treatment and outcome of spontaneous pneumothorax (SP) secondary to suspected migrating vegetal foreign body (MVFB).

METHODS

This retrospective study included dogs with computed tomography (CT) consistent with SP suspected to be secondary to MVFB that underwent thoracic surgery. They were divided into two groups according to whether CT identified (group 1) or only suspected (group 2) an MVFB.

RESULTS

Thirty-seven dogs were included (twenty-one in group 1 and 16 in group 2). An MVFB was identified during surgery in 18 of 21 of cases of group 1 and in 10 of 16 of group 2. An agreement between lobes affected on CT and surgical findings was observed in 34 of 40 lobes. In nine of 37 of cases, a lung perforation was identified without evidence of MVFB. Thirty-nine lobectomies were performed: 15 complete and 24 partial. No recurrence of pneumothorax was observed. In four dogs, a second surgery was necessary to remove an MVFB 1.5 to 3 months after the initial surgery due to secondary draining tracts.

CONCLUSION

Surgical approach planed with CT resolved SP in all cases before discharge with excellent short-term outcome and no major complication. CT was reliable to assess perforated lung lobes in 85% of cases. Clinical signs of delayed draining tract developed in 33% of cases where surgery failed to find an MVFB identified on CT.

Allogenic blood patch pleurodesis for continuous pneumothorax in three cats

Case series summary

Following diaphragmatic herniorrhaphy, three cats developed a continuous pneumothorax. All three cats required continuous suction to evacuate air from the thoracic cavity. Despite continuous suction, the pneumothorax persisted for all cats and blood patch pleurodesis (BPP) was performed using blood donor cats. All three cats had resolution of their pneumothorax within 24 h of BPP.

Relevance and novel information

This is the first report of BPP used in feline patients. More recently autologous BPP has been reported for use in dogs and humans, with a reportedly high success rate. BPP may allow timely resolution of continuous pneumothorax in cats and provide an alternative treatment option to prolonged medical management or surgical intervention. Allogenic blood from a donor cat may be necessitated in feline BPP when cardiovascular instability is appreciated in these small patients.

Spontaneous pneumothorax in two dogs undergoing combined laparoscopic ovariectomy and total laparoscopic gastropexy

Two dogs underwent a combined laparoscopic ovariectomy and total laparoscopic gastropexy. The intra-abdominal pressure and pulmonary compliance decreased, but the peak airway pressure increased at 20 min after the start of gastropexy with intracorporeal suturing. Right chest auscultation and percussion revealed reduced breath sounds and hyper-resonance. No abnormalities in the functioning of the instruments or diaphragmatic defects were detected. The tidal volume was reduced and a positive end-expiratory pressure of 5 cmH₂O was applied. The right chest of the two dogs was drained off: 950 mL (case 1) and 250 mL (case 2) of gas. After thoracentesis, the pulmonary compliance improved and surgery was completed successfully. The postoperative chest radiographs highlighted the residual right pneumothorax.

Radiography is less sensitive relative to CT for detecting thoracic radiographic changes in dogs affected by blunt trauma secondary to a motor vehicle accident

Thoracic injuries caused by blunt trauma are commonly encountered emergencies in veterinary medicine. However, published studies are lacking that compare radiology to CT in blunt trauma caused by motor vehicle accidents in canine patients. The aim of this prospective diagnostic accuracy, methods comparison study were to estimate the sensitivity (Se) and specificity (Sp) of thoracic radiology relative to CT for detecting lung contusions, pneumothorax, pleural effusion, and rib fractures. The study further aimed to develop a severity scoring system for radiology and CT and to compare the findings between the two modalities. The hypothesis was that radiology would be less sensitive than CT at detecting these injuries and that radiology would underestimate the severity of lung contusions. Fifty-nine patients met the inclusion criteria. Radiology underestimated the presence of lung contusions (Se = 69%, 95% confidence interval) and overestimated the severity of the contusions relative to CT. There was high interobserver variability in evaluating lung contusion severity (coefficient of variation = 91%). Both the three-view thoracic and horizontal beam radiography had poor sensitivities for the detecting pneumothorax (Se = 19% and 63%, respectively) and pleural effusions (Se = 43% and 71%, respectively). Similarly, the sensitivity (56%) of radiographs for the detection of rib fractures was poor relative to CT. Findings from the current study indicated that thoracic radiography had low sensitivity for detecting lesions related to blunt thoracic trauma caused by motor vehicle accidents and supported the use of CT as an additional diagnostic imaging modality in these patients.

[Spontaneous pneumothorax in cats: two case reports and literature review]

Spontaneous pneumothorax (SP) is a non-traumatic accumulation of air in the pleural cavity. This case report describes a cat with SP as a result of primary pulmonary adenocarcinoma. A second cat was diagnosed with primary pulmonary adenocarcinoma and asthma. A thoracostomy tube was inserted in the first cat while in the second cat a thoracostomy tube was placed and lobectomy of the right cranial and middle lung lobes was performed. Both cats died following treatment. The current literature reviewed here covers the comparative etiologies of SP as well as clinical presentation, diagnostic work-up, therapy and prognosis in cats. A total of 64 cases of cats with secondary spontaneous pneumothorax reported in nine articles are discussed. To our knowledge, there has been no previous description in the literature regarding primary SP in cats. Based on prior case reports, surgery was performed in 16% (10 cats) of SP cases. The current review demonstrates that depending on the underlying lung disease, cats with SP have a careful short-term prognosis because 39 of 64 cats (60%) were discharged.

Anticancer Therapeutic Alginate-Based Tissue Sealants for Lung Repair

Injury to the connective tissue that lines the lung, the pleura, or the lung itself can occur from many causes including trauma or surgery, as well as lung diseases or cancers. To address current limitations for patching lung injuries, to stop air or fluid leaks, an adherent hydrogel sealant patch system was developed, based on methacrylated alginate (AMA) and AMA dialdehyde (AMA-DA) blends, which is capable of sealing damaged tissues and sustaining physiological pressures. Methacrylation of alginate hydroxyl groups rendered the polysaccharide capable of photo-cross-linking when mixed with an eosin Y-based photoinitiator system and exposed to visible green light. Oxidation of alginate yields functional aldehyde groups capable of imine bond formation with proteins found in many tissues. The alginate-based patch system was rigorously tested on a custom burst pressure testing device. Blending of nonoxidized material with oxidized (aldehyde modified) alginates yielded patches with improved burst pressure performance and decreased delamination as compared with pure AMA. Human mesothelial cell (MeT-5A) viability and cytotoxicity were retained when cultured with the hydrogel patches. The release and bioactivity of doxorubicin-encapsulated submicrospheres enabled the fabrication of drug-eluting adhesive patches and were effective in decreasing human lung cancer cell (A549) viability.

Comparison of maximum force to failure of 4 thoracostomy tube connecting devices

OBJECTIVE

To compare the maximum force and displacement to failure of 4 different types of thoracostomy tube connecting devices.

STUDY DESIGN

Experimental in vitro study.

STUDY POPULATION

Four types of thoracostomy tube connecting devices (n = 10 each).

METHODS

Four different connecting device configurations (10 constructs each) were tested by maximum distraction to failure using a dynamometer: (1) CTTWW-a 3-way connector with a male luer slip attached to a thoracostomy tube by a Christmas tree adapter and secured to the tube with 21 gauge orthopedic wire; (2) CTTWRCW-a 3-way connector with a male luer lock with a rotating collar attached to a tube by a Christmas tree adapter and secured to the tube with 21 gauge orthopedic wire; (3) LVSBC-a Lopez valve attached to a tube with its short-barbed connector; and (4) LVLBC-a Lopez valve attached to a tube with its long-barbed connector.

RESULTS

The maximum distraction force to failure was significantly greater for CTTWRCW (250.9 N; range 143.7-293.6) than CTTWW (132.9 N; range 84.2-224.1), LVLBC (90.8 N; range 74.0-123.4), and LVSBC (54.6 N; range 39.6-164.2). The median displacement to failure of CTTWRCW (150 mm; range 54-190) was significantly longer than that of CTTWW (34.5 mm; range 22-70), LVLBC (32.5 mm; range 24-57), and LVSBC (16 mm; range 11-69).

CONCLUSION

The CTTWRCW group required greater force to create failure and had a longer displacement to failure, making it a more secure choice for connection to thoracostomy tubes.

Perioperative Blood Pressure Control and Management

Blood pressure monitoring and management is a vital part of the perianesthetic period. Disturbances in blood pressure, especially hypotension, can have significant impacts on the well-being of small animal patients. There are a variety of mechanisms present to control blood pressure, including ultra-short-, short-, and long-term mechanisms. Several conditions can contribute to decreased blood pressure, including anesthetics, tension pneumothorax, intermittent positive pressure ventilation, hypoxemia, hypercapnia, surgical positioning, and abdominal distension. If hypotension is encountered, the initial response is to provide appropriate fluid therapy. If this is inadequate, other interventions can be used to increase blood pressure and thereby increase perfusion.

Pneumopericardium, pneumomediastinum, pneumothorax and pneumoretroperitoneum complicating pulmonary metastatic carcinoma in a cat

This report describes a case of severe spontaneous tension pneumopericardium with concurrent pneumomediastinum, pneumothorax and retropneumoperitoneum in a cat presenting with dyspnoea and signs of cardiac tamponade secondary to metastatic pulmonary carcinoma. Spontaneous pneumopericardium is an extremely uncommon condition consisting of pericardial gas in the absence of iatrogenic/traumatic causes. In humans, it has been described secondary to pneumonia or lung abscess and very rarely secondary to pulmonary neoplasia.

Computed tomographic features of pneumothorax secondary to a bronchopleural fistula in two dogs

A bronchopleural fistula (BPF) can lead to continuous pneumothorax and is rarely reported clinically in dogs. This report describes computed tomographic (CT) findings in two dogs with BPFs and subsequent continuous pneumothoraces that necessitated thoracotomy. Both dogs had a peripheral BPF in the right caudal lung lobe. The fistula in one dog was secondary to a previous foreign body migration, and the fistula in the other was thought to be secondary to dirofilariasis. On both CT examinations, a dilated subsegmental bronchus was seen communicating with the pleural space at the center of a focal, concave region of parenchymal consolidation. Multiplanar reformatting aided in identification and characterization of the BPF. The pneumothoraces resolved after right caudal lobectomy in both dogs. CT has the potential to identify BPFs, such as secondary to foreign body migration or dirofilariasis.

Spontaneous pneumothorax secondary to reactive bronchopneumopathy in a dog

CASE DESCRIPTION

An 8-year-old 38-kg (84-lb) castrated male German Shepherd Dog cross was evaluated because of respiratory distress secondary to pneumothorax (detected radio-graphically prior to referral).

CLINICAL FINDINGS

CT of the thorax confirmed the presence of pneumothorax and revealed pulmonary blebs without evidence of infiltrative pulmonary changes. A tentative diagnosis of primary spontaneous pneumothorax was made.

TREATMENT AND OUTCOME

Exploratory median sternotomy revealed emphysematous changes along the margins of all lung lobes, with the ventral margins of the left cranial, right cranial, and right middle lung lobes most affected. Partial lobectomies of the ventral aspects of these lobes were performed. Histologic examination of tissue samples from the lung lobes revealed diffuse smooth muscle hypertrophy of the terminal and respiratory bronchioles with moderate numbers of peribronchiolar eosinophils. Mucus plugs and mucous cell metaplasia within the airway epithelium were also evident. After surgery, clinical signs resolved and the dog was discharged from the hospital 2 days later. Eight months after surgery, the dog developed a mild cough, and treatment with prednisolone (tapering dosage starting at 0.5 mg/kg [0.023 mg/lb], PO, q 12 h) was initiated. Dosage reduction resulted in recurrence of coughing; however, with continued prednisolone treatment at a dosage of 0.5 mg/kg, PO, once daily, the dog was not coughing at 10 months after surgery.

CLINICAL RELEVANCE

Reactive bronchopneumopathy should be included as a differential diagnosis for spontaneous pneumothorax in dogs.