Chapter 48 and 49 - Trachea and Thorax disorders Flashcards
What is the typical length of the equine trachea?
The equine trachea is approximately 70-80 cm long.
How many incomplete cartilage rings maintain the lumen of the equine trachea?
The lumen of the equine trachea is maintained by 48-60 incomplete cartilage rings.
Where does the trachea extend from and to which level in the horse’s body?
The trachea extends from the cricoid cartilage of the larynx to the level of the 5th or 6th intercostal space
How is the trachea divided into two parts?
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.
What is the structural significance of the incomplete cartilage rings in the equine trachea?
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
Describe the layers of the equine trachea’s outward structure.
The layers of the equine trachea outwardly consist of:
- mucosa,
- submucosa,
- musculo cartilaginous layer, and
- adventitia (cervical) or serosa (thoracic).
How does the mucosal layer of the equine trachea aid in protection?
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.
What is the role of cilia in the equine trachea?
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.
How does the trachea’s location change in relation to the cervical vertebral column and longus colli muscles?
The trachea is ventral to the cervical vertebral column and longus colli muscles.
What structures are found dorsolateral to the equine trachea?
Carotid sheaths enclose carotid arteries, vagosympathetic nerve trunks, and the recurrent laryngeal nerve (RLN).
What muscles cover the cervical trachea ventrally?
The sternothyrohyoideus muscles cover the cervical trachea ventrally.
Where is the favorite location for tracheotomy in horses?
The favorite location for tracheotomy in horses is in the cranial third where the sternocephalic muscle bellies and omohyoid muscle converge.
Why is caudal tracheal surgery not advised?
Caudal tracheal surgery is not advised due to the presence of the carotid sheath and the esophagus, which are more ventral in this region.
In young animals, what anatomical structure may extend from the thoracic cavity and lie on the ventral and lateral aspects of the trachea?
In young animals, the thymus may extend from the thoracic cavity and lie on the ventral and lateral aspects of the trachea
What complications might be encountered during tracheostomy in older horses or ponies?
In older horses or ponies, the trachea can have torsion and flattening, making tracheostomy more difficult.
How does the equine trachea’s characteristic rigidity contribute to its function?
The equine trachea’s characteristic rigidity, resulting from incomplete cartilage rings and smooth muscle, allows the passage of large boluses of food during inspiration.
What happens to the tracheal wall’s rigidity during intense exercise, and how is it compensated?
During intense exercise, the tracheal wall’s rigidity needs to increase. This is compensated by the elongation of the neck.
What is the shape of the tracheal lumen caudal to the larynx?
Caudal to the larynx, the tracheal lumen has a circular shape, which becomes dorsoventrally flattened as it courses caudally.
Why is the ellipsoidal shape of the trachea’s caudal aspect significant?
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.
What is the differnce between tracheotomy and tracheostomy?
cutting into the trachea “tomy”
surgical creation of a stoma has “S” for surgical stoma - sture skin with tracheal mucosa
The surgical procedure to access the tracheal lumen ventrally without the removal of tracheal rings is named…
tracheotomy
Describe surgical approach for tracheotomy
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
Describe surgical approach for tracheostomy with GA
**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
Describe standing procedure of tracheostomy
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
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
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)
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
Severe subcutaneous emphysema in a horse with tracheal perforaion trauma to the ventral aspect of the caudal neck
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.
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
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
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
*Following a successful repair, thesubcutaneous emphysema can be expected to resolve when?
1-2 weeks
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 clamps 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
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.
Coco et al EVE 2020 describe a dorsal intratracheal laceraton with subcut emphysema. What was used to seal?
Fibrin sealant
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
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
before a tracheal surgery the horse has to be trained to use what?
Martingale type harness that maintains the head in flexed position
name the instrument
Martingale harness
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
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 pattern 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 drain is placed next to the trachea, and the overlying tissue layers are closed.
Tracheal collapse is 2ary to what?
injury,abscess, tracheotomy (vertical)
What is the typical shape of tracheal collapse?
Dorsoventral> lateral
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
What are the grades of tracheal collapse?
4 grades -1 25% 2 50% 3 75% an 4collapse leaves less than 10 of thelumen unobstructed
During which phase of respiration does the maximum collapse of the cervical portion of the trachea occur?
Inspiration
What is a clinical sign of tracheal collapse affecting both cervical and thoracic trachea?
Honking noises on inspiration and abdominal expiratory effort.
What diagnostic method can reveal the abnormal shape of the trachea in cases of tracheal collapse?
Endoscopy.
What imaging technique can demonstrate the dynamic nature of tracheal collapse?
Fluoroscopy.
In emergency cases of severe respiratory distress in horses with tracheal collapse, what procedure might be performed?
Tracheotomy.
What complications are horses with tracheal collapse at high risk of?
Esophageal and carotid artery lacerations.
What is considered a safer method for nasotracheal intubation in horses with tracheal collapse?
Nasotracheal intubation with a small nasogastric tube and oxygen.
What are some methods of surgical treatment for tracheal collapse?
- Implantation of extraluminal prostheses,
- intraluminal stents,
- intraluminal stents + plication of the trachealis muscle.
Why are intraluminal stents associated with long-term complications?
They may lead to complications such as granulation tissue.
What are examples of extraluminal prosthetic devices used for tracheal support?
Titanium meshes or C-shaped polyethylene rings.
What complication can develop following circumferential mucosal injury in the trachea?
Tracheal stenosis.
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
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
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
What surgical treatment can be considered for tracheal stenosis?
Resection and anastomosis of the affected segment.
What type of foreign body is mentioned as a cause of tracheal obstruction in horses?
Thorny plant material.
How is the removal of intraluminal masses in the trachea typically performed?
Via tracheotomy or transendoscopic laser ablation.
Pleuropneumonia.
What is the response to surgical removal for benign masses such as papillomas or fibromas in the trachea?
They respond well to surgical removal.
What is the rare malignant tracheal tumor mentioned in the text?
SCC
Surgical reduction of the cricotracheal space and imbrication of the ligament.
How do you diagnose cricotracheal ligament collapse?
The endoscopic diagnosis is made if circumferential collapse of the ligament occurs during exercise
surgery being performed
Cricotracheal ligament imbrication and reduction of space
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
Iglesias-Garcia et al 2020 made an open approah to correct traumatic closed tracheal laceration through extraluminal or intralumnimal approach?
Intraluminal approach
Please mention the blood transfusion formula in case of hypovolemic shock due to hemorrhage
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
diagnosis
Rib fracture and pneumothorax
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).
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). (
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.
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.
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
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
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.
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).
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.
What device may facilitate the apposition of the thoracic wall during thoracotomy closure?
Rib contraction device (Bailey-Gibbon rib contractor).
diagnosis
Thoracotomy following surgery and 2nd intention healing
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
