Lung Flashcards
In a study by Rossanese 2020 in Vet Surg examining long term survival after lung lobe torsion, what was the most common breed affected? Did primary or secondary LLT have a better long term outcome?
Pugs most common breed (48%).
Primary LLT associated with a longer survival (MST not reached) compared to secondary (MST 921 days).
In a study by Scott 2022 in Vet Surg, what were the 3 reasons for conversion from thoracoscopic assisted to open lung lobectomy? What was the median period of hospitalization post-operative? What was the average size of lung tumour removed via VATS?
Adhesions, difficulty manipulating the lesion, acute oxygen desaturation.
The median period of hospitalization was 47 hours post-operative. MST was 168 days.
4.3 cm.
In a study by Montano 2023 in Vet Surg, what were two reasons for surgical intervention of traumatic pulmonary pseudocysts? Was conservative treatment successful in some cases?
Refractory pneumothorax, very large pseudocyst.
Conservative treatment was often successful for small pseudocysts.
According to Mather 2023 in Vet Surg, what was the ideal approach for lobectomy of the accessory lung lobe?
Right 6th intercostal space.
Note: the vascular anatomy of the accessory lung lobe was varied (lateral vein varied in location).
Name the structures in the following image from Mather 2023 in Vet Surg.
Name the structures in the following image from Mather 2023 in Vet Surg.
Name the structures in the following image from Mather 2023 in Vet Surg.
Name the structures in the following image from Mather 2023 in Vet Surg.
Name the structures in the following image from Mather 2023 in Vet Surg.
Name the structures in the following image from Mather 2023 in Vet Surg.
Name the structures in the following image from Mather 2023 in Vet Surg.
Name the structures in the following image from Mather 2023 in Vet Surg.
In a study by McPhetridge 2022 in JAVMA, what percentage of primary pulmonary neoplasms in dogs were carcinomas? What was the difference in survival for carcinomas, histiocytic sarcomas, and neuroendocrine tumours? What was the effect of chemotherapy on the survival of patients with carcinoma?
Pulmonary carcinomas accounted for 87% of cases (histiocytic sacroma 6%, neuroendocrine 2%).
MST were 400 days for pulmonary carcinoma, 300 days for histiocytic sacroma, and 500 days for neuroendocrine tumours.
There was no effect of chemotherapy on the survival of patients with pulmonary carcinoma when grouped according to stage.
In a study by Parry 2023 in JAVMA, what 3 characteristics were associated with an increased risk of malignancy on CT of cavitary pulmonary lesions?
Heterogenous contrast enhancement, additional pulmonary nodules, wall thickness >40mm at their thickest point.
In a study by Park 2024 in JAVMA, what percentage of canine lung tumours removed thoracoscopically were carcinoma? What 2 factors were associated with an increased risk for conversion? What was the MST, and what factor was associated with decreased survival?
81% of tumours were carcinomas (clean margins in 88%).
Conversion occurred in 26% of patients and was more likely in tumours >5cm and when lymphadenopathy was detected on CT pre-operatively.
MST was 311 days, and presence of enlarged tracheobronchial lymph nodes on pre-operative CT scans were associated with shorter post-op survival.
What vessel sealing device did Bruckner 2019 in JSAP use for lung biopsy and total lung lobectomy in canine cadavers?
The Caimen vessel sealing device. Can be used on vessels up to 7mm, with 1mm lateral thermal spread. Extent of collateral damage in this paper was 3mm.
Which lung lobe does localized histiocytic sarcoma most frequently affect?
Right middle (three types of described histiocytic sarcoma include localized, disseminated [from dendritic cells] and haemophagocytic [from macrophages])
In a study by Shimbo 2021 in VRU, what breeds were predisposed to anomalous systemic arterial supply to the normal lung? Which lung lobes were most frequently affected? What is ASANL?
Labrador retrievers, shetland sheepdogs, and miniature dachshunds are predisposed.
The caudal lung lobes are most commonly affected.
ASANL is an abnormality in which systemic arteries direct from the aorta supply the basal segments of the lower lobe (lung is lacking pulmonary arterial supply to this segment). Can cause pulmonary hypertension and left sided cardiac overload.
In a study by Kim 2023 in VRU, was there a sex or lung lobe predilection for incidental bullas identified on CT scan? Were adverse events identified in patients with bullae undergoing anesthesia for CT or additional procedures?
There was no sex or lung lobe predilection, although older animals were at increased risk.
No adverse events were identified in patients undergoing anesthesia for various reasons.
According to Tindale 2022 in JFMS, what were the two most common clinical signs in cats with lung lobe torsion? Which lung lobes were typically affected? Was idiopathic or secondary lung lobe torsion more common? Which was associated with a better outcome?
Tachypnoea and dyspnoea. Pleural effusion was common at presentation.
The right middle, left and right cranial lung lobes were most frequently affected.
Secondary lung lobe torsion (7/10) was more common than primary (3/10).
Primary lung lobe torsion cases had a much better outcome (all 3 survived and had excellent outcomes) compared to secondary disease (all 7 cats died within 5 weeks of discharge).
In a study by Nylund 2019 in Vet Surg, did use of a LigaTie (pictured) or 3.5 mm TA 55 stapling device result in high leakage pressures for peripheral lung biopsy?
LigaTie (majority reached the maximum pressure of 40 cm H2O without leaking).
In a study by Ichimata 2023 in JVIM, what was the overall survival time reported for small breed dogs with pulmonary adenocarcinoma after surgical resection? What 2 factors were associated with reduced progression free interval? What factor was associated with reduced OST?
OST 716 days,
Tumours >5cm <7cm, and incomplete margin were associated with decreased PFI.
Increasing age was associated with reduced OST.
How many sternebrae are present in the dog?
9
The intercostal arteries are branches of which artery?
The aorta, anastomose with the the internal thoracic artery. The first intercostal artery is the exception to this arising from the costocervical trunk.
Where do the intercostal veins drain?
The azygous vein, except for the first intercostal vein which drains to the costocervical vein.
What is the anatomic relationship of the pulmonary arteries and veins to each bronchus?
Artery: craniodorsal to the bronchus.
Vein: caudoventral to the bronchus.
What arteries supply oxygenated blood to the airways?
Bronchial branches of the bronchoesophageal arteries. Terminate in capillary beds with the pulmonary arteries at the level of the respiratory bronchioles.
Describe the lobes of the lung.
What muscles function to increase expansion of the chest wall during periods of increased ventilatory demand?
Serratus ventralis, external intercostals, sternocleidomastoid, scalenus.
Under normal conditions of respiration the diaphragm is primarily responsible for inspiration and elastic recoil is responsible for expiration.
What factors have to be overcome to facilitate inspiration?
Lung elastance (∆P/∆V), alveolar surface tension (surfactant reduces surface tension and improves compliance), airway resistance.
Lung compliance (∆V/∆P) can be modified by fibrosis or pulmonary edema.
Inspiratory airway resistance is caused by the nares (79%), larynx (6%), and small airways (15%).
How do changes in PaCO2 cause a change in ventilation?
Changes in PaCO2 are detected by chemoreceptors in the medulla and aortic/carotid bodies.
A small increase in PaCO2 causes a marked increase in ventilation.
Below what level does PaO2 cause an increase in ventilation?
Less than 60 mmHg causes a ventilation increase (hypoxic ventilation drive).
What is the normal tidal volume of the dog?
10 ml/kg
What is Fick’s law as it related to diffusion of gases?
That the rate of transfer of a gas through a sheet of tissue is proportional to surface area available for diffusion, diffusion coefficient of the gas, and difference in gas partial pressure between the two sides and inversely proportional to the tissue thickness (distance the gas must travel).
Does CO2 or O2 have a higher diffusion coefficient?
CO2 (20 times that of oxygen). Clinical significance is that diffusion impairment may occur for oxygen well before CO2, resulting in normocapnia and hypoxemia.
What percentage of oxygen in the blood is bound to hemoglobin?
99%
What factors can shift the oxygen dissociation curve to the right resulting in greater unloading of oxygen?
Acidosis, increased temperature, CO2, and 2,3-diphosphoglycerate in RBCs.
What is the PaO2 of arterial and venous blood?
Arterial: 100 mmHg (SaO2 98%).
Venous: 40 mmHg (SaO2 75%).
How is arterial oxygen concentration calculated?
CaO2 = (1.36 × Hb × SaO2) + 0.003 PaO2
In what form is the majority of carbon dioxide transported in the blood?
Bicarbonate.
What are some causes of high and low V/Q mismatch?
High: pulmonary thromboembolism.
Low: atelectasis, pneumonia, pulmonary edema.
What are some potential causes of hypoxemia (SaO2 <90%)?
Hypoventilation, diffusion impairment, shunting, decreased fraction of inspired oxygen, V/Q mismatch.
What is a normal alveolar oxygen pressure to arterial blood partial pressure difference (PA-aO2)?
10 mmHg.
Oxygen supplementation should be initiated at 20 mmHg, severe gas impairment is present when there is a difference greater than 30 mmHg.
Which of the causes of hypoxemia are oxygen and non-oxygen responsive?
Oxygen responsive: diffusion impairment, low fraction of inspired oxygen, high V/Q mismatch.
Non-oxygen responsive: low V/Q mismatch, shunting.
What are some consequences of thoracotomy on pulmonary physiology?
Hypoxemia is common post-operatively secondary to reduced ventilation, diffusion impairment, and V/Q mismatch (atelectasis).
Residual pneumothorax or pleural effusion may worsen hypoxemia, while pain prevents appropriate thoracic wall excursion.
At what intercostal space should cranial and caudal lung lobectomies be performed?
Cranial: 4th or 5th intercostal.
Caudal: 5th or 6th.
Right middle is accessed through the right 5th intercostal space.
Intercostal thoracotomy allows access to approximately one third of the ipsilateral thoracic cavity.
What is the difference between pulmonary cysts, bullae and blebs?
Cysts: are covered by a respiratory epithelium. Most frequently caused by blunt trauma to the chest.
Bullae and blebs (pseudocysts): have no epithelial lining. Bullae are large air spaces that develop within the lung parenchyma. Blebs are small accumulations of air between the parenchyma and visceral pleura. Often caused by obstructive lung disease.
What is the sensitivity of CT for detecting bullae/blebs in instances of spontaneous pneumothorax?
42-58%
In instances of spontaneous pneumothorax in which lung lobes are the bulla or blebs most frequently reported during thoracic exploration?
Cranial lung lobes
What is the goal of mechanical pleurodesis in the treatment of spontaneous pneumothorax?
Aims to induce extensive pleural adhesions, reducing the risk of recurrence. However successful production of complete adhesions is uncommon in dogs.
Is lung abscessation more common in cats or dogs?
Cats, although relatively rare in both species.
Exudation coming from a single main bronchus during bronchoscopy is highly suggestive of what disease?
Local infection with a high suspicion for a foreign body.
What are the most common bacteria isolated from dogs and cats with pneumonia?
Dogs: E.coli, Klebsiella, Staph, Strep, Pseudomonas, Fusobacterium.
Cats: Nocardia, Corynebacterium.
What is the surgical treatment for lung consolidation/abscessation?
Median sternotomy and lung lobectomy of affected lobes (<50% total lung volume) +/- decortication if restrictive pleuritis is present.
What is the outcome following lung lobectomy for consolidation in dogs?
Outcome is better if consolidation is due to foreign body or fungal infection as compared to bacterial pneumonia.
Single lung lobectomy associated with 14% mortality (60% if three lobes resected).
What are the two types of bronchiectasis?
Sacculated: if lesion is located to a portion of the bronchial wall.
Cylindrical: if the lesion affects the entire wall.
What is the effect of bronchiectasis on the surrounding alveoli?
Atelectasis due to airway obstruction and alveolar compression.
Which lung lobe is most frequently affected by bronchiectasis?
Right cranial lung lobe.
Which imaging techniques can be used to diagnose bronchiectasis?
Radiography +/- contrast, CT, bronchoscopy.
What is the prognosis for bronchiectasis?
Poor, MST of 16 months.
Lung lobectomy can be performed if only 1 or 2 lobes affected, but requires aggressive medical management of respiratory infection post-operative to prevent further progression.
When is surgery indicated for patients with lung laceration?
If intrapleural air does not resorb in 3-4 days.
How are lung lacerations surgically repaired?
Median sternotomy and leak testing to identify location. Primary repair performed using mattress sutures (if tissue is friable may need to be mounted on Teflon pledgets). Deep lacerations at the periphery may be treated by partial lung lobectomy, if near the hilus primary airway repair should be performed followed by closure of the parenchyma in a mattress pattern.
Which lung lobes are most typically affected by lung lobe torsion?
Left cranial or right middle.
In pugs the left cranial is predominantly affected.
Which dogs are most commonly affected by lung lobe torsion?
Deep chested dogs, can be spontaneous or secondary to another disease (chylothorax).
Pugs are also predisposed and thought to be spontaneous in this breed. Generally <4.5 years of age, and males are predisposed.
What are some conditions that lung lobe torsion has been associated with?
Chronic respiratory disease, chylothorax, trauma, diaphragmatic hernia, thoracic surgery, and neoplasia
What imaging techniques can be used for the diagnosis of lung lobe torsion?
Radiography: pleural effusion, lung consolidation, emphysema of the affected lobe (97%), irregular/narrowed/blunted bronchus (45-75%), mediastinal shift, dorsal tracheal displacement.
CT: bronchi are narrowed, collapsed, or occluded and have abrupt terminations.
Ultrasound, positive contrast bronchography, and bronchoscopy can also be used.
What is the preferred method of lung lobectomy in cases of lung lobe torsion?
Stapler, as it allows lobectomy with the lung in its torsed position. Otherwise the pedicle should be clamped before it is untwisted and ligation of the vessels and bronchus performed.
What is the prognosis for lung lobe torsion?
Fair, survival rates of 50-61% have been reported with more favourable survival in pugs.
What is the most common primary pulmonary neoplasm?
Carcinoma of alveolar or bronchial origin.
Metastatic disease is much more common than primary neoplasia in general.
What percentage of cats with a primary pulmonary mass develop lung digit syndrome?
18%
Which lung lobes are most frequently affected by pulmonary neoplasia?
Caudal lung lobes (if the right middle or left cranial lung lobe is affected by a large mass, histiocytic sarcoma is likely).
Is fine needle aspiration of suspected pulmonary neoplasia high-yield?
Yes, provides a diagnosis in 80% of cases.
Potential complications include hemoptysis, pneumothorax, and death. Complications can be reduced by the use of ultrasound guidance and 22 or 25 gauge needles.
What are prognostic factors for dogs with primary pulmonary neoplasia?
Histologic cell type, tumor size, presence of metastasis, presence of pleural effusion, and clinical signs.
The prognosis is best for dogs that have a solitary, well-differentiated carcinoma smaller than 5 cm in diameter; no regional lymph node metastasis; and no malignant pleural effusion (50% of these patients survive 1-year).
What is the MST for dogs with primary pulmonary neoplasia with and without
metastatic disease?
With metastatic disease MST = 26 days, without metastatic disease = 452 days.
What are prognostic factors for cats with primary pulmonary neoplasia?
Presence of clinical signs or pleural effusion, moderately and poorly differentiated tumors, and evidence of metastases.
MST ranges from 11 - 698 days.
What are some surgical techniques for partial lung lobectomy?
- Sutured partial lobectomy (see image).
- Stapled partial lobectomy.
- Thoracoscopic partial lobectomy (pretied ligature can be used for biopsies of <3cm of tissue from the periphery, 2.5mm endoGIA can be used for partial lobectomy).
- Keyhole technique (mini thoracotomy approach).
What sizes of endoGIA stapler are available?
Leg lengths of 2.0, 2.5, 3.5, 4.8mm.
Cartridge lengths of 30, 45 and 60mm.
Leg length of 2.5mm is preferred for partial lung lobectomy, 3.5mm for total lung lobectomy.
What are some surgical techniques for total lung lobectomy?
- Suture ligation.
- Stapled technique (typically using either a TA V3 30mm, or TA55 with 3.5mm staples).
- Thoracoscopic (60mm endoGIA with 3.5mm staple length), or thoracoscopic assisted.
For thoracoscopic lung lobectomy what minimum size of patient is recommended?
> 10kg, with tumours <8cm in diameter. One lung ventilation is typically required.
When is pneumonectomy indicated?
For lesions that have extended to all lobes of one lung but have spared the contralateral lung
How much lung volume can be completely removed acutely in the dog? What percentage of total lung volume do the left and right lung lobes comprise?
50% can be removed acutely (75% results in death).
Left lung: 42% of overall mass.
Right lung: 58%.
Therefore acute removal of the entire right lung volume will likely result in death (unless a disease process has led to a slow, progressive reduction in lung function on that side).
What changes are seen in the contralateral lung and myocardium following pneumonectomy?
Decrease in lung compliance, vital capacity, and perfusion. Right ventricular hypertrophy and increased pulmonary vascular resistance.
Compensatory improvement of oxygen transport occurs secondary to recruitment of physiologic reserves of diffusion capacity, remodeling of existing alveolar-capillary structures, and growth of new alveolar-capillary units.
