Chapter 48 and 49 - Trachea and Thorax disorders Flashcards
(179 cards)
1
Q
What is the typical length of the equine trachea?
A
The equine trachea is approximately 70-80 cm long.
2
Q
How many incomplete cartilage rings maintain the lumen of the equine trachea?
A
The lumen of the equine trachea is maintained by 48-60 incomplete cartilage rings.
3
Q
Where does the trachea extend from and to which level in the horse’s body?
A
The trachea extends from the cricoid cartilage of the larynx to the level of the 5th or 6th intercostal space
4
Q
How is the trachea divided into two parts?
A
The trachea is divided into cervical and thoracic parts.
The cervical part is connected to the larynx via the cricotracheal ligament, while the thoracic part starts at the thoracic inlet and continues on midline until it is slightly deflected to the right by the aortic arch.
5
Q
What is the structural significance of the incomplete cartilage rings in the equine trachea?
A
The incomplete cartilage rings are** open dorsally**, and the smooth trachealis muscle spans the gap between the free ends. This arrangement allows the contraction of smooth trachealis muscle to change the lumen diameter without altering the luminal profile. This allows big bolus of food to pass in esophagus
6
Q
Describe the layers of the equine trachea’s outward structure.
A
The layers of the equine trachea outwardly consist of:
- mucosa,
- submucosa,
- musculo cartilaginous layer, and
- adventitia (cervical) or serosa (thoracic).
7
Q
How does the mucosal layer of the equine trachea aid in protection?
A
The mucosal layer contains pseudostratified columnar ciliated epithelium with numerous goblet cells, forming a mucous layer that provides moisture and helps trap foreign bodies and pathogens, offering protection.
8
Q
What is the role of cilia in the equine trachea?
A
Cilia in the equine trachea function in transporting mucus orally at a rate of 0.24 cm/min, contributing to the mucociliary escalator, which acts as a barrier against airway infection.
9
Q
How does the trachea’s location change in relation to the cervical vertebral column and longus colli muscles?
A
The trachea is ventral to the cervical vertebral column and longus colli muscles.
10
Q
What structures are found dorsolateral to the equine trachea?
A
Carotid sheaths enclose carotid arteries, vagosympathetic nerve trunks, and the recurrent laryngeal nerve (RLN).
11
Q
What muscles cover the cervical trachea ventrally?
A
The sternothyrohyoideus muscles cover the cervical trachea ventrally.
12
Q
Where is the favorite location for tracheotomy in horses?
A
The favorite location for tracheotomy in horses is in the cranial third where the sternocephalic muscle bellies and omohyoid muscle converge.
13
Q
Why is caudal tracheal surgery not advised?
A
Caudal tracheal surgery is not advised due to the presence of the carotid sheath and the esophagus, which are more ventral in this region.
14
Q
In young animals, what anatomical structure may extend from the thoracic cavity and lie on the ventral and lateral aspects of the trachea?
A
In young animals, the thymus may extend from the thoracic cavity and lie on the ventral and lateral aspects of the trachea
15
Q
What complications might be encountered during tracheostomy in older horses or ponies?
A
In older horses or ponies, the trachea can have torsion and flattening, making tracheostomy more difficult.
16
Q
How does the equine trachea’s characteristic rigidity contribute to its function?
A
The equine trachea’s characteristic rigidity, resulting from incomplete cartilage rings and smooth muscle, allows the passage of large boluses of food during inspiration.
17
Q
What happens to the tracheal wall’s rigidity during intense exercise, and how is it compensated?
A
During intense exercise, the tracheal wall’s rigidity needs to increase. This is compensated by the elongation of the neck.
18
Q
What is the shape of the tracheal lumen caudal to the larynx?
A
Caudal to the larynx, the tracheal lumen has a circular shape, which becomes dorsoventrally flattened as it courses caudally.
19
Q
Why is the ellipsoidal shape of the trachea’s caudal aspect significant?
A
The ellipsoidal shape of the trachea’s caudal aspect is easier to collapse than a circular lumen shape, which can have implications for respiratory function.
20
Q
What is the differnce between tracheotomy and tracheostomy?
A
cutting into the trachea “tomy”
surgical creation of a stoma has “S” for surgical stoma - sture skin with tracheal mucosa
21
Q
The surgical procedure to access the tracheal lumen ventrally without the removal of tracheal rings is named…
A
tracheotomy
22
Q
Describe surgical approach for tracheotomy
A
10 cm incision through skin, subcut, cutaneus colli muscle
The pair sternothyrohoideus muscle bellies are blunty divided along the ventral midline
Transverse tracheotomy is the recommended in horses – anular ligament between 2 adjacente cartilage rings is incised parallel to the orientation of rings
23
Q
Describe surgical approach for tracheostomy with GA
A
**DR + neck extended in slight flexion
Align skin and tachea to natural position
10 cm ventral midline incision
Sternothyroihyoideus is separated to expose 4 to 5 tracheal rings
3-cm-wide band of each of the overlying muscles is bluntly s**eparated, crushed, and transected **on either side of the midline
the ventral third of the** second** through the** fifth or sixth ring are removed**
Ventral midline and two paramedian incisions, 15mm on either side of the midline, are made through the ** tracheal cartilages without disrupting the underlying tracheal mucosa**
Rectangular cartilage pieces are carefully dissected
**Tracheal mucosa and annular ligaments **are incised in a double-Y pattern
mucosa is sutured to the skin in a simple-interrupted pattern using 0 or 2-0 polydioxanone or polyglactin 910 suture material
24
Q
Describe standing procedure of tracheostomy
A
Very similar to GA
LA in an inverted U pattern
Start 3 cm caudal to the cricoid and** extend caudal 8 cm**
Remove eliptical segment of skin to reduce risk of skin inversion
excision of the sternothyrohyoideus segments as described for GA, a 3-cm section of the omohyoid muscle can be removed on either side to prevent future collapse of the stoma
*Before the cartilage rings are incised on the ventral midline, each ring can be compressed laterally to push its ventral aspect away from the underlying mucosa
*From here, dissection of the ring from the submucosa is continued abaxially for 1.5 cm, at which point the cartilage is cut from the inside to the outside same finish as the previous
25
What is the psotoperative care?
AB and NSAID for 3 to 5 days and clean twice daily
Feed high so it doesn't do execisse stretching of the suture
26
What is the issue doing a traheostomy in a mare?
*broodmares **lose the ability to exhale against a closed glottis,** a technique that is used to increase abdominal pressure during the second stage of labor (Valsalva maneuver)
27
What are the common complicatios post tracheostomy?
- partial dehiscence (10% before and 5% after hospital discharge)
- transient fever (12%)
- excessive swelling (16%),which might be caused by hematoma formation
*Continued work of the mucociliary escalator appears to be sufficient and secondary pneumonia has not been reported
*Removal of the central third of the tracheal rings is important to prevent postsurgical tracheal collapse
Older animals, the trachea may become rotated
28
Severe subcutaneous emphysema in a horse with tracheal perforaion trauma to the ventral aspect of the caudal neck
29
What is the principal presenting complaint in horses with perforation of the cervical trachea, especially in the absence of obvious external signs of injury?
Subcutaneous emphysema, with or without dyspnea, is the principal presenting complaint in horses with perforation of the cervical trachea.
30
What can happen if the subcutaneous air from a tracheal perforation reaches the mediastinum?
Once the caudal neck is affected, the subcutaneous air can dissect along muscle layers and facial planes to reach the mediastinum. Which can lead to **pneumomediastinium** that can **rupture mediastinal pleura** and lead to **threatening pneumothorax**
31
What can result if the air reaches the mediastinum?
*Resulting pneumomediastinum is often clinically silent, but continued air accumulation can rupture the mediastinal pleura and lead to a potentially life-threatening pneumothorax
32
What is the treament in a small blunt trauma?
*Perforations of the cervical trachea without loss of tissue or extensive damage to the tracheal rings should be débrided and sutured with No. 0 absorbable suture material in a simple interrupted pattern
*Closed suction drains are placed and can generally be removed after 48 to 72 hours
33
*Following a successful repair, thesubcutaneous emphysema can be expected to resolve when?
1-2 weeks
34
Tracheal resection and anastomosis is indicated in extense complete rupture between rings describe the surgery?
**Flexion** of the **head by 90º reduces** tension of the anastomotic site by about 50%
DR (use thin endotracheal tube to pass resection site)
**Ventral midline incision over defaut**
skin - subcut - **cutaneous colli muscles**
Resection of **1 tracheal can be performed if incsion is 20 cm** - but you have to open more if several rings are removed
Division of the paired **sternothyrohyoideus muscles** exposes the trachea
**Stay sutures above** and **bellow the removal of damaged cartilage rings**
**Tracheal mucosa + annular ligament** are incised immediately adjacent to the cartilages to be removed
**Once trachea completely transect remove the tube** and **reinsert sterile tube** inserted into caudal segment
Use 2-0 continuous pattern
**Tracheal mucosa is turned back over the open ends** and **sutured to the adventitia**
**Tracheal ends appose with towel clamp**s and anastomosed with **25G stainless steel wire** in **simple interrupted pattern WITHOUT mucosal penetration**
Stay sutures are removed - check for air leaks
Continuous suction drain placed next to the trachea
Overlying tissue layers closed
35
describe the surgical tx name
Figure 48-9. Surgical technique for tracheal anastomosis. (A) Removal of a tracheal ring without penetration of the mucosa. (B) A 360-degree incision of mucosa between remaining cartilage rings. (C) Eversion of mucosa, followed by suturing of mucosa to adventitia. (D) Anastomosis of tracheal segments with stainless-steel sutures.
36
Coco et al EVE 2020 describe a dorsal intratracheal laceraton with subcut emphysema. What was used to seal?
Fibrin sealant
37
What is important to place before recovery of tracheal anastomosis? When do you remove suction drains?
Martingale type of harness kept for 3 weeks - to avoid extension of the head
3-4 days after removal of suction drain
38
Complications of tracheal anastomosis
- Infection
- peritracheal abscessation
- formation of intraluminal granuloma
- fistulas form around the steel sutures,their removal may be necessary after the anastomosis has healed
- Intraoperative damage to the recurrentlaryngeal nerve
39
before a tracheal surgery the horse has to be trained to use what?
Martingale type harness that maintains the head in flexed position
40
name the instrument
Martingale harness
41
The flexion of the head with Martingale harness reduces the tension on the anastomosis of how much?
50% which is particularly important if more than one ring is removed
42
describe the surgical setps of tracheal anastomosis
**Ventral midline incision** centered over the affected area, is made through **skin, subcutaneous tissue and cutaneus colli muscles**.
**Resection of one tracheal ring** can be performed through a skin incision of **less than 20 cm**, but the opening has to be significantly longer if several rings need to be removed.
**Division of the paired sternothyrohyoideus muscles** exposes the trachea, which is separated from the adjacent tissues over the length of the incision. **Ligation of vessels dorsal and lateral to the trachea** might be necessary.
Prior to removal of damaged cartilage rings, **stay-sutures are placed around the tracheal rings ** above and below the intended resection site to **avoid sudden retraction of the two ends**.
The **tracheal mucosa** and **annular ligament **are **incised immediately adjacent to the cartilages that are to be removed**. Once the trachea has been completely transected, the **endotracheal tube is pulled back** and a sterilized tube is inserted into the caudal segment. Using a** 2-0 suture** in a** simple continuous pattern**, the **tracheal mucosa is turned back over the open ends of the cranial tracheal segment and sutured to the adventitia**; on the caudal segment it is necessary to work around the tube. The** head is flexed at a right angle**, the tracheostomy tube removed and the endotracheal tube advanced across the resection site into the caudal segment of the trachea. **Tracheal ends are apposed with towel clamps and anastomosed with 25-gauge stainless-steel wire** in a **simple-interrupted patter**n **without mucosal penetration** (Figure 48-9).
The previously placed **stay-sutures** can be **removed or tied across the anastomotic site to provide additional tension-relief.** Successful apposition after removal of a single ring has also been accomplished with four **No. 3 cerclage **wires and simple interrupted mucosal sutures. After the anastomosis is complete, it is checked for air leaks before the **endotracheal tube** is completely withdrawn. A **continuous suction drai**n is placed next to the trachea, and the overlying tissue layers are closed.
43
Tracheal collapse is 2ary to what?
injury,abscess, tracheotomy (vertical)
44
What is the typical shape of tracheal collapse?
Dorsoventral> lateral
45
What are the typical breed affected by tracheal collapse?
Small breed ponies, mules, donkeys with chondromalacia being the main cause of tracheal collapse in AMH
46
What are the grades of tracheal collapse?
4 grades -1 25% 2 50% 3 75% an 4collapse leaves less than 10 of thelumen unobstructed
47
During which phase of respiration does the maximum collapse of the cervical portion of the trachea occur?
Inspiration
48
What is a clinical sign of tracheal collapse affecting both cervical and thoracic trachea?
Honking noises on inspiration and abdominal expiratory effort.
49
What diagnostic method can reveal the abnormal shape of the trachea in cases of tracheal collapse?
Endoscopy.
50
What imaging technique can demonstrate the dynamic nature of tracheal collapse?
Fluoroscopy.
51
In emergency cases of severe respiratory distress in horses with tracheal collapse, what procedure might be performed?
Tracheotomy.
52
What complications are horses with tracheal collapse at high risk of?
Esophageal and carotid artery lacerations.
53
What is considered a safer method for nasotracheal intubation in horses with tracheal collapse?
Nasotracheal intubation with a small nasogastric tube and oxygen.
54
What are some methods of surgical treatment for tracheal collapse?
1. Implantation of extraluminal prostheses,
2. intraluminal stents,
3. intraluminal stents + plication of the trachealis muscle.
55
Why are intraluminal stents associated with long-term complications?
They may lead to complications such as granulation tissue.
56
What are examples of extraluminal prosthetic devices used for tracheal support?
Titanium meshes or C-shaped polyethylene rings.
57
What complication can develop following circumferential mucosal injury in the trachea?
Tracheal stenosis.
58
how do you diagnose tracheal collapse?
Turbulent airflow in the cervical trachea may be auscultated and allow localization of the site of collapse
Auscultation can be a way with **cervical** being **most severe during inspiration** when decreasing pressure in the tracheal luen exacerbates the narrowing
expiration, when the increasing surrounding pressures compress the trachea
59
horses with severe tracheal collapse appear to be at a high risk for ___________________ and ____________ ________(3w) during tracheotomy,
horses with severe tracheal collapse appear to be at a high risk for esophageal and carotid artery lacerations during tracheotomy
60
Causes of tracheal stenosis
There are 2 causes:
following a **circumferential mucosal injury **
or a **transverse tracheotomy** where **more than 50% of the circumference** of the annular ligament was transected
61
What surgical treatment can be considered for tracheal stenosis?
Resection and anastomosis of the affected segment.
62
What type of foreign body is mentioned as a cause of tracheal obstruction in horses?
Thorny plant material.
63
How is the removal of intraluminal masses in the trachea typically performed?
Via tracheotomy or transendoscopic laser ablation.
64
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What is a potential complication of foreign body obstruction in the trachea?
Pleuropneumonia.
65
What is the response to surgical removal for benign masses such as papillomas or fibromas in the trachea?
They respond well to surgical removal.
66
What is the rare malignant tracheal tumor mentioned in the text?
SCC
67
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In cases of cricotracheal ligament collapse, what surgical procedure you advise?
Surgical reduction of the cricotracheal space and imbrication of the ligament.
68
How do you diagnose cricotracheal ligament collapse?
The endoscopic diagnosis is made if circumferential collapse of the ligament occurs during exercise
69
surgery being performed
Cricotracheal ligament imbrication and reduction of space
70
EVE 2020 Madsen reports a
Bronchopleural fistula that consists of a direct communication between the bronchail tree and pleural sace. Control endoscopy following seal of glue covering brochopleural fistula and the b) is control 8 w posto where granulation tissue is sealing the bronchopleural fistula
71
Iglesias-Garcia et al 2020 made an open approah to correct traumatic closed tracheal laceration through extraluminal or intralumnimal approach?
Intraluminal approach
72
What structures define the boundaries of the thoracic cavity in horses?
**diaphragm,** traced from the point of the **elbow (6th rib) to the point of the shoulder (10th rib)** and **dorsocaudally to the transverse processes **of the last **thoracic vertebrae (17th–18th rib).**
73
What components form the pleural space, and where is it located?
The **parietal pleura lines the thoracic cavity,** and the **visceral pleura encloses the lungs**. The pleural space is located between these two components.
74
Where is the cardiac notch located in the lungs of the horse?
The cardiac notch **divides** the **cranial and caudal lobes of the lungs**, with an additional accessory lobe on the right side.
75
What structures does the parietal pleura encase axially in the thoracic cavity?
The parietal pleura encases the **heart, great vessels, thymus** (in neonates), **trachea, esophagus, lymphoid tissue, and nerves.**
76
At what intercostal spaces is the horse's heart located?
The heart stands on its apex, is tipped slightly forward, and is located between the** 2nd and 6th intercostal spaces.** (same in cows)
77
What maintains lung expansion during exhalation in horses?
**Negative pressure** within the pleural space, coupled with thoracic stiffness and alveolar surfactant.
78
What are the active and passive components of both inhalation and exhalation in horses?
Inhalation begins with a passive reexpansion of the thorax followed by a longer active phase. The majority of exhalation is passive, with an active component at the end of the cycle.
79
What clinical signs may be observed in horses with external injuries to the thoracic region?
**Stiffness at the walk, anxiety** from thoracic pain, or severe signs of **hypovolemic shock from hemorrhage.**
80
What respiratory distress signs may indicate internal thoracic injuries in horses?
Excessive respiratory effort, nostril flaring, tachypnea, dyspnea, accentuated thoracic excursion, and cyanotic mucous membranes.
81
In horses with axillary wounds, what complication can occur days after the injury?
Severe subcutaneous emphysema leading to **pneumomediastinum.**
82
How does hemothorax and pneumothorax affect the respiratory pattern in horses?
Horses develop a rapid and shallow respiratory pattern due to the restriction of lung expansion caused by the presence of fluid or air in the pleural cavity.
83
What is a likely cause of rapidly developing respiratory distress in horses? and shallow respiratory?
Pneumothorax or severe pulmonary contusion
Shallow: hemothorax and thoracic woundns/ rib fx.
84
Please mention the blood transfusion formula in case of hypovolemic shock due to hemorrhage
85
In case of absence of respiratory sounds and increment on ressonance percussion it is indicative of what?
Pneumothorax
86
What is the significance of localized crepitus in horses with thoracic trauma?
It suggests the presence of fractured ribs.
87
What diagnostic method is more valuable for confirming the presence of pleural fluid and identifying rib fractures in horses?
Thoracic ultrasonography.
88
Figure 1 Image (b) There are well-defined, linear, streaky, gas
opacities dorsal to the dorsal margin of the trachea and aorta
resulting in increased conspicuity of these structures. What is the likely diagnosis? a. Tracheal collapse
b. Pneumothorax
c. Pneumomediastinum
d. Pulmonary bulla
c) Pneumomediastinum
Gas is seen dorsal to the tracheal and aorta, which are both
structures within the mediastinum. In a standing horse, gas
within the pleural space would likely collect caudodorsally.
Figure - The white arrows in images (b) and (d) incitate gas dorsal to the trachea, and white arrowheads dorsal to the ascending aorta indicate gas at the dorsocranial aspect of the
aorta. The white asterisk inicates the aorta and the black asterisk indicates the cardiac silhouette
89
diagnosis
Rib fracture and pneumothorax
90
What condition is diagnosed by the presence of air outlining the mediastinal contents on radiographs?
Pneumomediastinum
91
What laboratory examination parameters are recommended for assessing the respiratory system in horses?
Arterial blood gas analyses to determine acid-base status, ventilatory function, and tissue oxygenation.
92
Why should radiographs be taken quickly in horses with severe respiratory distress?
To evaluate the presence of pneumothorax, with separation of lung margins from the diaphragm and vertebral bodies, indicating a collapsed lung.
93
What is the primary purpose of thoracocentesis in horses?
To obtain a sample of pleural fluid for analysis or to drain air or fluid from the pleural space.
94
What analyses should be performed on aspirated pleural fluid from horses?
Cytologic analysis, aerobic and anaerobic cultures, and antibiotic sensitivity testing.
95
Describe thoracoscopy standing sedated
Stocks - sedation xylazine or detomidine or CRI deto (0.01mg/kg) and butor for analgesia (0.04mg/kg) local anesthesia of the skin (**15–20 mL of 2% lidocaine** per portal site), subcutaneous tissue, intercostal musculature, and costal pleura.
The sites for the thoracoscope and instrument portals depend on the surgical intervention.
**Induce pneumothorax **through cannula inserted by** 1cm stab incision cranial to 10th-12th ICS (avoid vessel in caudal ribs)** to avoid damage to the lung with thoracoscope that is replaced by **10-mm trocar–cannula system** The trocar is subsequently removed and replaced by the **telescope**
**Instrument portals :** multiple instrument portals are placed at least **10 to 15 cm apart (two to three intercostal spaces**) to avoid obstruction of vision or restriction of instrument manipulations.
96
What is the potential risk associated with the presence of a pneumothorax during thoracoscopy in horses?
Transient hypoxemia (PO2<80 mmHg) attributed to ventilation/perfusion mismatch and a slight decrease in cardiac output.
97
Why is analysis of arterial blood gases considered essential during thoracoscopy in horses?
To evaluate ventilation (hypoventilation if PCO2>50 mmHg) and oxygen exchange (hypoxemia if PO2<80 mmHg), especially in horses with compromised lung function.
98
Describe the thoracoscopy under GA for biopsy
GA biospy technique can be sternal, lateral or DR (DR preferred with Trendelenburg for observation of cranial structures
**Thorascope portal **is placed at** 12th-13th IC**space and (cow 9th -10th ICS)
one **instrument portal **is placed **1 or 2 IC spaces cranial **and **15 cm VENTRAL to the thoracope**
**2nd instrument portal **is inserted **15th IC 10 cm ventral to the thorascope** for babcock
Negative pressure restablished
Insufflate máx 3 mmHg of CO2
99
What is the recommended intervention for horses with hypoxia during thoracoscopy?
Intranasal administration of O2 (10 L/min).
Pneumothorax 15L/min
100
Why should thoracoscopy portals be placed just cranial to the intercostal spaces in horses?
To avoid **vessels and nerves located caudal to the ribs** and allow extensive exploration of the thorax.
101
What technique is used to induce a pneumothorax before inserting the thoracoscope in horses and avoid damage to the lung?
Inserting a teat cannula into the thoracic cavity through an incision, inducing a unilateral pneumothorax.
102
What position is recommended for a horse during thoracoscopy under general anesthesia for improved viewing of the ventral lung surfaces?
Dorsal recumbency, slightly leaning toward the opposite operating site (45 degrees) in a reverse Trendelenburg position.
103
Why is positive-pressure ventilation considered necessary during thoracoscopy under general anesthesia in horses?
To prevent bilateral pneumothorax, which can occur more easily in the anesthetized horse.
104
What method is preferred for resection of pulmonary wedges during thoracoscopy in horses?
Endoscopic stapling devices.
*Ligasure Vessel sealing system (LVSS) has been recently shown to be another effective method to obtain a pulmonary samplein normal horses and horses with clinical signs of heaves
105
What is a limitation of the pre-tied ligating loop technique for obtaining pulmonary samples in horses?
Relatively high rate of complications due to slippage of the ligating loop and inability to predetermine biopsy size.
106
What potential complications may arise during thoracoscopy in horses?
Injury to **lung parenchyma or diaphragm**,
**injury to intercostal vessels,**
**pain during manipulation,**
**residual pneumothorax,**
difficulty exposing the area of interest,
and **mild respiratory distress.**
107
What is considered essential after obtaining a lung biopsy with any instrument during thoracoscopy in horses?
Ensuring complete hemostasis and sealing of the lung parenchyma to prevent postoperative pneumothorax and hemothorax.
108
What is pneumothorax, and how does it occur in the pleural cavity?
Pneumothorax refers to the accumulation of air in the pleural cavity, occurring as a result of pulmonary or chest wall injury.
109
What leads to the development of a pressure gradient during pneumothorax?
A communication between the atmosphere and the pleural space.
110
How does lung function get compromised in pneumothorax?
The lung collapses to its minimal volume.
111
What causes closed pneumothorax, and when does it commonly occur?
Closed pneumothorax results from leakage of air from the pulmonary parenchyma or an airway tear, commonly occurring after blunt trauma causing rib fractures.
112
Explain tension pneumothorax and how it develops.
**Tension pneumothorax** results when air leakage acts like **a one-way valve,** allowing air **entry into the pleural cavity** but not permitting its escape.
113
What are the consequences of increasing intrathoracic pressure in tension pneumothorax?
**Severe cardiovascular and pulmonary compromise,** potentially fatal if not treated promptly and aggressively.
114
What are the main physiologic consequences of pneumothorax?
Decrease in the vital capacity of the lung and a decrease in the partial pressure of arterial O2 (PaO2).
115
How does hypoxia, resulting from pneumothorax, affect horses?
It may lead to myocardial dysfunction, lactic acidosis, and increased work for the right side of the heart.
116
Horse presented with pneumothorax how would you manage?
Adequate ventilation by nasal O2 5-15L/min
Fluidotherapy if tachycardia (2-4 mL/kg)
Restore blood volume
Systemic analgesia
Restrict exercise and apply bandage - crosstie the horse
Thoracocenthesis and reestabishment of negative pleural pressure 12-1th ICS bellow epaxial muscles air removed slowly with Heimlick valve or three-way stopcock
117
Why is pneumothorax frequently bilateral in horses?
Due to the incomplete mediastinum that exists in horses.
118
What clinical signs are associated with pneumothorax in horses?
Restlessness, cyanosis, tachypnea, dyspnea, unilateral thoracic expansion, and accentuated respiratory excursions
119
ABC
Figure 49-2. Thoracoscopically guided lung biopsy in a horse. The caudodorsal aspect of the lung lobe is grasped with Babcock forceps (A), and using endoscopic staples (B), the pulmonary wedge resection is performed (C).
120
Describe internal fixation of ribs in neonates
´Plates (2,7mm) + cortex screws (2,7 mm)/ LHS´Lateral recumb(if bilat fx à repair more critical side first)
´Incision overeach fx rib or repair through one incision
´4-6 screws engaging both cortices (4-6 cortices on each fx fragment)
´Cerclage wire (18-22G) encircling rib + plate at 2 sites above and below fx à prevent implant pullout
121
Figure 49-4. (A) Intraoperative view during repair of a displaced rib fracture in a foal. Notice the reconstructive plate, cortex screws, and cerclage wires. Towel clamps were used to reposition and align the fracture fragments. (B) Postoperative radiograph of a fractured rib in a foal, repaired with the same technique, using a reconstructive plate (white arrow), cortex screws, and cerclage wires. Note the caudal aspect of the distal humerus (black arrowheads). (
122
Figure 49-9. Thoracic radiographs of a horse with chronic pleuropneumonia and a large pulmonary abscess (arrowheads). Pleural effusion was removed via pleurocentesis prior to radiographic evaluation.
123
How is thoracocentesis performed for pneumothorax in horses?
A large-gauge needle, teat cannula, or thoracostomy tube is inserted between the **12th and 15th intercostal spaces** just below the **epaxial muscles.**
124
Figure 49-10. Thoracoscopic view of the left pleural cavity in a horse with pleuropneumonia. (A) The collapsed lung (L) is adhered to the parietal pleura by fibrinous adhesions (arrow). (B) With the use of endoscopic instruments, the lung is separated from the adhered parietal pleura. (C) After adequate drainage was established, a large chest tube (arrow) was introduced into the thorax and the pleural cavity was lavaged with isotonic saline.
125
how would you manage a foal with simple rib fracture?
Management of foals with simple rib fractures consists of strict confinement for 1 to 4 weeks and supportive care with analgesics, antiinflammatory drugs, antibiotics, and antiulcerShallow, rapid breathing due to increased respiratory frequency and decreased tidal volume.
126
How is hemothorax developed in horses, and what signs may be observed?
It develops secondary to trauma causing laceration of intercostal blood vessels, myocardium, pulmonary parenchyma, or thoracic wall musculature. Signs include hypovolemic shock, anemia, and pain.
127
Foals with flail chest and concomitant pulmonary trauma are kept recumbent with the affected side down or up?
Foals with flail chest and concomitant pulmonary trauma are **kept recumbent with the affected side down**, and intranasal oxygen insufflation is administered. Lateral recumbency with the affected lung down minimizes ventilatory impairment of the better-ventilated lung (on top). Or place them sternal and sedate
128
Figure 49-5. (A) Schematic of a fractured rib (cranial is to the right and ventral is at the bottom) showing suture placement using an 80-pound nylon strand (SCCLRS). (B) Complete reduction of the fracture after application of the tension device and closure of the SCCLRS crimp clamp (arrow).53
129
In foals that need rib fracture repair and is bilateral which side should be up?
For the surgery, the foal is placed in lateral recumbency with the affected side up. In foals with bilateral fractures, the side with more critical fractures is repaired first
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Describe the 80 pound nylon strand tx
´Repair multiple fx in foals
´Nylon strandin figure-of-eight through holes drilled in the cranial cortex of the proximal and distal fx fragments, secured with Securus Cranial Cruciate Ligament Repair System crimp clamps´Noinflammatory reaction, eventually covered by bone
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Surgical techniques available according to Velloso Alvarez 2022 Survival and racing performance after surgical tx of rib fractures in foals?
Closed technique using percutaneous suture or wire with external plint
Reconstruction plates (4- to8- holes 2.7 mm reconstrunction plates) secured with screws and/or wire
Nylon cable ties
132
Why is bacterial pleuropneumonia often considered expensive and time-consuming?
It requires prolonged resolution and aggressive treatment, leading to significant expenses and time investment.
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Figure 49-6. Ultrasonographic image of the left thoracic cavity of a horse with pleural effusion. A moderate volume of pleural effusion has resulted in collapse (atelectasis) of the ventral tip of the lung.
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Figure 49-8. Ultrasonographic image of the right thorax of a horse with chronic pleuropneumonia. Minimal pleural effusion is evident (arrowhead). Consolidated or abscessed lung is evident by the break in the pleural surface and the ability to image the deeper parenchyma (arrow).
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What factors influence survival rates in horses with pleuropneumonia?
Survival rates vary based on microbial pathogens, rapidity of diagnosis, appropriate treatment, and the development of secondary complications.
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Figure 49-7. Ultrasonographic image of the left visceral pleura of a horse with peracute pleuropneumonia. The pleural surface casts irregular acoustic shadows or “comet tails” (arrows) that are the result of pleural surface roughening. Subsequent reevaluation revealed progressive accumulation of pleural fluid and pulmonary consolidation.
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What is the common consequence for horses surviving pleuropneumonia?
Many survivors are unable to return to their previous level of performance.
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Which group of horses is more likely to develop pleuropneumonia in the United States, and what risk factor is identified?
Thoroughbred horses in race training are 4.3 times more likely, suggesting that career, not breed, is the risk factor.
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What factors increase the risk of lower airway contamination with general anesthesia?
1 Endotracheal intubation,
2 dorsal recumbency,
3 anesthetic-induced depression of respiratory defense mechanisms.
140
In Great Britain, which group of horses has the highest risk of developing pleuropneumonia?
Show jumpers.
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What are the clinical signs during the peracute stage of pleuropneumonia?
Fever, inappetence, lethargy, depression, and exercise intolerance.
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What conditions have been associated with an increased risk of pleuropneumonia?
Penetrating thoracic injuries and pulmonary aspiration secondary to esophageal obstruction or upper airway dysfunction.
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How might pleurodynia (pleural pain) manifest in horses with pleuropneumonia?
Anxiety, pawing, reluctance to move, abduction of the elbows, and grunting when the thorax is percussed.
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What may be revealed through auscultation during the progression of pleuropneumonia, indicating acute to chronic stages?
Ventral dullness with pleural friction rubs and adventitial sounds (crackles and wheezes) in the dorsal lung fields.
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How can nasal discharge be indicative of the severity of pleuropneumonia?
A chronic brown, bloody nasal discharge indicates pulmonary hemorrhage and infarction.
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What diagnostic methods are used for bacterial pleuropneumonia?
Clinical findings, complete blood count,
ultrasonographic and
radiographic findings, and
positive bacterial culture of tracheal wash and pleural fluid samples.
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What is the significance of thoracic percussion in diagnosing pleuropneumonia?
It can detect and outline the extent of pleural effusion or pulmonary consolidation.
148
How does ultrasonography contribute to the diagnosis of pleuropneumonia?
It assesses the volume and type of effusion, determines the ideal site for pleurocentesis, and provides information on pleural irregularities
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Why is thoracic radiography useful in evaluating pleuropneumonia?
It determines the extent of pulmonary consolidation and evaluates progression over time.
150
What are the common clinical laboratory findings in the acute stage of pleuropneumonia?
Hyperfibrinogenemia and neutropenia with a toxic left shift.
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What is the recommended treatment for bacterial pleuropneumonia?
Early institution of appropriate antimicrobial therapy, often a combination of a penicillin (or cephalosporin) and an aminoglycoside.
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What tool is recommended for assessing the development of pleural abscesses or necrotic lung tissue when subcutaneous air interferes with ultrasonography?
Thoracoscopy.
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What is considered the second important part of medical management in pleuropneumonia?
Drainage of the pleural effusion.
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What can be the consequence of accumulation of fibrin and debris in pleuropneumonia cases over time?
Closure of the mediastinal fenestrations, requiring bilateral thoracocentesis to remove bilateral effusion.
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How can drainage be facilitated in pleuropneumonia cases, and what complications might arise with indwelling tubes?
Ultrasound-guided placement of small cannulas or catheters; complications include obstruction with fibrin or debris and localized cellulitis.
156
When is open drainage via thoracotomy recommended for pleuropneumonia cases?
It should be considered for chronic pleural effusion that has responded poorly to medical therapy, localized or unilateral disease processes, walled-off abscesses, or when tube drainage is inadequate.
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How is the horse's tolerance for pneumothorax assessed before performing open thoracic drainage?
It can be done with thoracoscopy or by inserting a large chest tube into the targeted cavity and leaving it open prior to thoracotomy.
158
Why is general anesthesia in lateral recumbency recommended for draining abscesses in the cranial mediastinum?
Horses with compromised pulmonary function and poor candidates for general anesthesia are better managed in lateral recumbency.
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What is the mandatory requirement for positive-pressure ventilation during thoracotomy to drain intrathoracic abscesses?
Positive-pressure ventilation with a mechanical ventilator.
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What is the preferred surgical approach to drain intrathoracic abscesses determined by?
Localization of the abscess by radiography and ultrasonography.
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How is the standing approach for thoracotomy initiated in terms of anesthesia and incision?
Local anesthesia is infiltrated, followed by a 15- to 25-cm incision through the skin, intercostal musculature, and pleura over the selected intercostal space.
162
When is rib resection usually not necessary during thoracotomy?
Rib resection is usually not necessary, but if elected, it involves a 30-cm incision over the selected rib.
´skin –cutaneus trunci – latissimus dorsi – serratus ventralis - periosteum
!! Superficial thoracic vein, intercostal vessels´ Periosteum circumferentially elevated ´Obstetric wirepssed around proximal aspect rib transected +desarticulation costochondral junction à removal 25 cm rib
´Stab incision periosteum + pleura, enlager with scissors
´Finochetto rib retractor for exposure (! Discomfort)
´Thoracic exploration + debridement + ansvess drainage + lavage
Evtl kt placement in abscess then removed / left in situ
163
Why is vigorous irrigation discouraged during thoracotomy in horses with pleuropneumonia?
frequently results in severe coughing and discomfort due to bronchopleural fistulation commonly present in horses with pleuropneumonia.
164
How is the thoracic incision managed after exploration and débridement in thoracotomy?
It is left open, and the diseased cavity is irrigated twice daily until the surgical wound heals by second intention.
165
Why is general anesthesia via closed thoracotomy considered?
It should be considered when an approach to the lung will result in pneumothorax.
166
What device may facilitate the apposition of the thoracic wall during thoracotomy closure?
Rib contraction device (Bailey-Gibbon rib contractor).
167
# **
How is the periosteum apposed during the closure of thoracotomy?
Carefully with size 0 or 1 absorbable suture material in a simple-interrupted pattern
168
What is the purpose of tightening the final suture in the first layer of thoracic wall closure during thoracotomy?
It is tightened while the lungs are fully inflated to reestablish the normal negative pressure of the pleural cavity.
169
What complications may arise after thoracotomy?
Cardiac arrhythmias, thoracic wall abscesses, chronic draining tracts, local cellulitis, and severe bilateral pneumothorax.
170
What is the variation in the survival rate for horses with bacterial pleuropneumonia according to retrospective reports?
It varied from 43% to 75%.
171
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What is associated with an increase in pleural fluid volume and overall mortality, according to a recent study?
The presence of fibrinous adhesions within the pleural cavity.
172
What is the positive response to treatment in pleuropneumonia indicated by?
Resolution of fever, return of appetite, and gradual reduction in the volume of effusion.
173
How long should recovery time be allowed after the resolution of the underlying infection before returning to training and performance?
At least 3 to 6 months.
174
Where are located the intercostal vessels?
caudal
175
diagnosis
Thoracotomy following surgery and 2nd intention healing
176
Describe pericardiectomy standing by Silva-Meirelles et al EVE 2020
Access to the thoracic cavity was obtained by means of a skin incision of approximately 2 cm in the 5th left intercostal space for the first three procedures, and in the 6th intercostal space for the last three, aligned with the scapulohumeral joint.
Incision and blunt divulsion of the musculature were performed and, with the use of a Cocker hemostat, the incision was deepened until the parietal pleura was perforated, resulting in pneumothorax.
Through theopening, a 11 mm cannula with endotip was introduced,along with a 10 mm optic coupled to a micro camera.
The pneumothorax was established with carbon dioxide andadjusted to a maximum pressure of 4 mmHg.
Pericardium was pulled with the Hook forceps towards theribs in a way to hold the myocardium avoiding lesions bycontact with the surgical instrument, then an incision wasmade from cardiac base to apex, exposing the left atrialappendage
Pericardiectomy was then initiated with a smallincision of approximately one centimetre and, from thisopening, the pericardium was drawn, facilitating theenlargement of the opening, to approximately 30 cm.
Musculature was approximated and muscleand skin sutures where performed with a nonabsorbable no 2polypropylene thread, pneumothorax resolved by aspiration
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Diagnosis of this case report from Kamus et al EVJ 2021 Use of barbed suture for thoracoscopic repair of....
Right traumatic thoracic wound of horse diaphragmatic hernia with 10 mm laparoscopic cannula inserted through 12th ICS cranial is to the left
d) Intra-operative laparoscopic image of horse 2 depicting the diaphragmatic rent on the left dorsal quadrant
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Describe the standing surgical technique accordingly to Kamus et al EVJ 2021
Standing - deto/butor/deto CR 0.02mg/kg/h IV) LA
First, a **10-mm camera portal** was created at the **12th ICS just ventrally to the longissimus dorsi muscle**
Exploration of the pleural cavity revealed a **12–13cm diameter diaphragmatic defect** in the right dorsal quadrant (Figure 1b) at the level of the wound.
The liver was visible through the defect and prevented intestinal herniation.
A 32 Fthoracic drain was next placed in the distal aspect of the **9th ICSto drain the haemothorax (14 L),**i mprove visualisation and perform pleural lavage post-operatively.
Two standard instrument portalswere then created at the **13th (4–5cm distally to the first portal)**and **14th ICS (aligned with the camera portal)**.
**laparoscopic instruments (needle holder, Babcock forceps, Kellyforceps and scissors)** the laceration was closed with absorbable **barbed suture (0 USP, V-Loc180**, 15 cm, Covidien, Medtronic Ltd)placed in a simple continuous fashion).
Thoracic wound debrided and closed by 1ary closure
Thorascopic portals closed routinely
**Thoracic negative pressure was re-established at the end of the surgery by aspiration of the right pneumothorax.** A 16F thoracic drain wasplaced in the proximal aspect of the left 13th ICS to drain a contralateralpneumothorax that developed during surgery. Lastly, a 32F abdominal drain was placed ventrally in the right aspect ofthe abdomen to perform post-operative lavage given the suspicionof abdominal contamination during the injury
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Preop considerations in a thoracic trauma
**Clean **and **pack the wound **with sterile **gauz**e and **16 French drain in the 13th IC to drain pneumothorax**
Give **intranasal oxygen (15L/min)**
**RL IV, sodium penicilin, gentamicin (6.6 mg/kg IV SID), metronidzadole** (20 mg/kg TID) and flunixim meglumine (1.1 mg/kg) It is very painful so analgesia is important with butorphanol (0.01 mg/kg IV extra)
