Lung

Question 1

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?

Answer 1

Pugs most common breed (48%).
Primary LLT associated with a longer survival (MST not reached) compared to secondary (MST 921 days).

Question 2

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?

Answer 2

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.

Question 3

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?

Answer 3

Refractory pneumothorax, very large pseudocyst.

Conservative treatment was often successful for small pseudocysts.

Question 4

According to Mather 2023 in Vet Surg, what was the ideal approach for lobectomy of the accessory lung lobe?

Answer 4

Right 6th intercostal space.
Note: the vascular anatomy of the accessory lung lobe was varied (lateral vein varied in location).

Question 5

Name the structures in the following image from Mather 2023 in Vet Surg.

Answer 5

Question 6

Name the structures in the following image from Mather 2023 in Vet Surg.

Answer 6

Question 7

Name the structures in the following image from Mather 2023 in Vet Surg.

Answer 7

Question 8

Name the structures in the following image from Mather 2023 in Vet Surg.

Answer 8

Question 9

Name the structures in the following image from Mather 2023 in Vet Surg.

Answer 9

Question 10

Name the structures in the following image from Mather 2023 in Vet Surg.

Answer 10

Question 11

Name the structures in the following image from Mather 2023 in Vet Surg.

Answer 11

Question 12

Name the structures in the following image from Mather 2023 in Vet Surg.

Answer 12

Question 13

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?

Answer 13

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.

Question 14

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?

Answer 14

Heterogenous contrast enhancement, additional pulmonary nodules, wall thickness >40mm at their thickest point.

Question 15

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?

Answer 15

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.

Question 16

What vessel sealing device did Bruckner 2019 in JSAP use for lung biopsy and total lung lobectomy in canine cadavers?

Answer 16

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.

Question 17

Which lung lobe does localized histiocytic sarcoma most frequently affect?

Answer 17

Right middle (three types of described histiocytic sarcoma include localized, disseminated [from dendritic cells] and haemophagocytic [from macrophages])

Question 18

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?

Answer 18

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.

Question 19

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?

Answer 19

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.

Question 20

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?

Answer 20

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).

Question 21

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?

Answer 21

LigaTie (majority reached the maximum pressure of 40 cm H2O without leaking).

Question 22

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?

Answer 22

OST 716 days,

Tumours >5cm <7cm, and incomplete margin were associated with decreased PFI.

Increasing age was associated with reduced OST.

Question 23

How many sternebrae are present in the dog?

Answer 23

9

Question 24

The intercostal arteries are branches of which artery?

Answer 24

The aorta, anastomose with the the internal thoracic artery. The first intercostal artery is the exception to this arising from the costocervical trunk.

Question 25

Where do the intercostal veins drain?

Answer 25

The azygous vein, except for the first intercostal vein which drains to the costocervical vein.

Question 26

What is the anatomic relationship of the pulmonary arteries and veins to each bronchus?

Answer 26

Artery: craniodorsal to the bronchus. Vein: caudoventral to the bronchus.

Question 27

What arteries supply oxygenated blood to the airways?

Answer 27

Bronchial branches of the bronchoesophageal arteries. Terminate in capillary beds with the pulmonary arteries at the level of the respiratory bronchioles.

Question 28

Describe the lobes of the lung.

Answer 28

Question 29

What muscles function to increase expansion of the chest wall during periods of increased ventilatory demand?

Answer 29

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.

Question 30

What factors have to be overcome to facilitate inspiration?

Answer 30

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%).

Question 31

How do changes in PaCO2 cause a change in ventilation?

Answer 31

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.

Question 32

Below what level does PaO2 cause an increase in ventilation?

Answer 32

Less than 60 mmHg causes a ventilation increase (hypoxic ventilation drive).

Question 33

What is the normal tidal volume of the dog?

Answer 33

10 ml/kg

Question 34

What is Fick's law as it related to diffusion of gases?

Answer 34

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).

Question 35

Does CO2 or O2 have a higher diffusion coefficient?

Answer 35

CO2 (20 times that of oxygen). Clinical significance is that diffusion impairment may occur for oxygen well before CO2, resulting in normocapnia and hypoxemia.

Question 36

What percentage of oxygen in the blood is bound to hemoglobin?

Answer 36

99%

Question 37

What factors can shift the oxygen dissociation curve to the right resulting in greater unloading of oxygen?

Answer 37

Acidosis, increased temperature, CO2, and 2,3-diphosphoglycerate in RBCs.

Question 38

What is the PaO2 of arterial and venous blood?

Answer 38

Arterial: 100 mmHg (SaO2 98%). Venous: 40 mmHg (SaO2 75%).

Question 39

How is arterial oxygen concentration calculated?

Answer 39

CaO2 = (1.36 × Hb × SaO2) + 0.003 PaO2

Question 40

In what form is the majority of carbon dioxide transported in the blood?

Answer 40

Bicarbonate.

Question 41

What are some causes of high and low V/Q mismatch?

Answer 41

High: pulmonary thromboembolism. Low: atelectasis, pneumonia, pulmonary edema.

Question 42

What are some potential causes of hypoxemia (SaO2 <90%)?

Answer 42

Hypoventilation, diffusion impairment, shunting, decreased fraction of inspired oxygen, V/Q mismatch.

Question 43

What is a normal alveolar oxygen pressure to arterial blood partial pressure difference (PA-aO2)?

Answer 43

10 mmHg. Oxygen supplementation should be initiated at 20 mmHg, severe gas impairment is present when there is a difference greater than 30 mmHg.

Question 44

Which of the causes of hypoxemia are oxygen and non-oxygen responsive?

Answer 44

Oxygen responsive: diffusion impairment, low fraction of inspired oxygen, high V/Q mismatch. Non-oxygen responsive: low V/Q mismatch, shunting.

Question 45

What are some consequences of thoracotomy on pulmonary physiology?

Answer 45

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.

Question 46

At what intercostal space should cranial and caudal lung lobectomies be performed?

Answer 46

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.

Question 47

What is the difference between pulmonary cysts, bullae and blebs?

Answer 47

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.

Question 48

What is the sensitivity of CT for detecting bullae/blebs in instances of spontaneous pneumothorax?

Answer 48

42-58%

Question 49

In instances of spontaneous pneumothorax in which lung lobes are the bulla or blebs most frequently reported during thoracic exploration?

Answer 49

Cranial lung lobes

Question 50

What is the goal of mechanical pleurodesis in the treatment of spontaneous pneumothorax?

Answer 50

Aims to induce extensive pleural adhesions, reducing the risk of recurrence. However successful production of complete adhesions is uncommon in dogs.

Question 51

Is lung abscessation more common in cats or dogs?

Answer 51

Cats, although relatively rare in both species.

Question 52

Exudation coming from a single main bronchus during bronchoscopy is highly suggestive of what disease?

Answer 52

Local infection with a high suspicion for a foreign body.

Question 53

What are the most common bacteria isolated from dogs and cats with pneumonia?

Answer 53

Dogs: E.coli, Klebsiella, Staph, Strep, Pseudomonas, Fusobacterium. Cats: Nocardia, Corynebacterium.

Question 54

What is the surgical treatment for lung consolidation/abscessation?

Answer 54

Median sternotomy and lung lobectomy of affected lobes (<50% total lung volume) +/- decortication if restrictive pleuritis is present.

Question 55

What is the outcome following lung lobectomy for consolidation in dogs?

Answer 55

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).

Question 56

What are the two types of bronchiectasis?

Answer 56

Sacculated: if lesion is located to a portion of the bronchial wall. Cylindrical: if the lesion affects the entire wall.

Question 57

What is the effect of bronchiectasis on the surrounding alveoli?

Answer 57

Atelectasis due to airway obstruction and alveolar compression.

Question 58

Which lung lobe is most frequently affected by bronchiectasis?

Answer 58

Right cranial lung lobe.

Question 59

Which imaging techniques can be used to diagnose bronchiectasis?

Answer 59

Radiography +/- contrast, CT, bronchoscopy.

Question 60

What is the prognosis for bronchiectasis?

Answer 60

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.

Question 61

When is surgery indicated for patients with lung laceration?

Answer 61

If intrapleural air does not resorb in 3-4 days.

Question 62

How are lung lacerations surgically repaired?

Answer 62

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.

Question 63

Which lung lobes are most typically affected by lung lobe torsion?

Answer 63

Left cranial or right middle. In pugs the left cranial is predominantly affected.

Question 64

Which dogs are most commonly affected by lung lobe torsion?

Answer 64

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.

Question 65

What are some conditions that lung lobe torsion has been associated with?

Answer 65

Chronic respiratory disease, chylothorax, trauma, diaphragmatic hernia, thoracic surgery, and neoplasia

Question 66

What imaging techniques can be used for the diagnosis of lung lobe torsion?

Answer 66

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.

Question 67

What is the preferred method of lung lobectomy in cases of lung lobe torsion?

Answer 67

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.

Question 68

What is the prognosis for lung lobe torsion?

Answer 68

Fair, survival rates of 50-61% have been reported with more favourable survival in pugs.

Question 69

What is the most common primary pulmonary neoplasm?

Answer 69

Carcinoma of alveolar or bronchial origin. Metastatic disease is much more common than primary neoplasia in general.

Question 70

What percentage of cats with a primary pulmonary mass develop lung digit syndrome?

Answer 70

18%

Question 71

Which lung lobes are most frequently affected by pulmonary neoplasia?

Answer 71

Caudal lung lobes (if the right middle or left cranial lung lobe is affected by a large mass, histiocytic sarcoma is likely).

Question 72

Is fine needle aspiration of suspected pulmonary neoplasia high-yield?

Answer 72

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.

Question 73

What are prognostic factors for dogs with primary pulmonary neoplasia?

Answer 73

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).

Question 74

What is the MST for dogs with primary pulmonary neoplasia with and without metastatic disease?

Answer 74

With metastatic disease MST = 26 days, without metastatic disease = 452 days.

Question 75

What are prognostic factors for cats with primary pulmonary neoplasia?

Answer 75

Presence of clinical signs or pleural effusion, moderately and poorly differentiated tumors, and evidence of metastases. MST ranges from 11 - 698 days.

Question 76

What are some surgical techniques for partial lung lobectomy?

Answer 76

1. Sutured partial lobectomy (see image). 2. Stapled partial lobectomy. 3. 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). 4. Keyhole technique (mini thoracotomy approach).

Question 77

What sizes of endoGIA stapler are available?

Answer 77

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.

Question 78

What are some surgical techniques for total lung lobectomy?

Answer 78

1. Suture ligation. 2. Stapled technique (typically using either a TA V3 30mm, or TA55 with 3.5mm staples). 3. Thoracoscopic (60mm endoGIA with 3.5mm staple length), or thoracoscopic assisted.

Question 79

For thoracoscopic lung lobectomy what minimum size of patient is recommended?

Answer 79

>10kg, with tumours <8cm in diameter. One lung ventilation is typically required.

Question 80

When is pneumonectomy indicated?

Answer 80

For lesions that have extended to all lobes of one lung but have spared the contralateral lung

Question 81

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?

Answer 81

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).

Question 82

What changes are seen in the contralateral lung and myocardium following pneumonectomy?

Answer 82

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.