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Large Animal Surgery > Equine Thorax > Flashcards

Equine Thorax Flashcards

1
Q

What kind of trauma commonly affects the equine thorax?

A

penetrating —> fence posts, branches, HBC

(can’t be managed like in cattle!)

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2
Q

What are the 4 major signs of thoracic trauma in horses?

A
  1. shock - hypovolemic due to blood loss
  2. respiratory distress - shallow breaths, nostril flaring, increased effort and thoracic excursion
  3. hypoventilation - cyanotic MM (muddy purple/grey)
  4. pain - tachycardia, stiff gait (hard to move with FB in thorax)
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3
Q

What is the goal when evaluating thoracic penetrating wounds? What are important diagnostic/prognostic steps?

A

determining extent of injury and ruling out abdominal involvement that can lead to colic

  • PE - thoracic auscultation!
  • blood gas
  • PCV/TP
  • radiographs
  • ultrasound - better for air and fluid buildup
  • wound exploration
  • thoracocentesis
  • thoracoscopy
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4
Q

What is the normal pH, PCO2, and HCO3- in horses?

A

7.35-7.45

35-45 mmHg

22-26 mEq/L

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5
Q

How are pH, PCO2, and HCO3- affected by metabolic acidosis and alkalosis?

A

ACIDOSIS = pH <7.35, decreased HCO3- (<22)

ALKALOSIS = pH >7.45, increased HCO3- (>26)

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6
Q

How are pH, PCO2, and HCO3- affected by respiratory acidosis and alkalosis?

A

ACIDOSIS = pH <7.35, increased PCO2 (>45)

ALKALOSIS = pH >7.45, decreased PCO2 (<35)

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7
Q

What are common causes of metabolic acidosis and alkalosis?

A

ACIDOSIS = diarrhea, lactic acidosis, renal failure

ALKALOSIS = proximal GI obstruction, vomiting

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8
Q

What are common causes of respiratory acidosis and alkalosis?

A

ACIDOSIS = hypoventilation

ALKALOSIS = hyperventilation

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9
Q

Blood gas:

A
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10
Q

A venous blood gas from a horse with thoracic trauma shows the following:

  • pH = 7.2
  • PCO2 = 65 mmHg
  • HCO3- = 25

What is the primary disorder?

A

primary respiratory acidosis

  • low pH
  • increased PCO2
  • normal HCO3- (may have compensation)
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11
Q

What are the 3 major steps in triaging and stabilizing patients with thoracic trauma? What is avoided?

A
  1. treat shock by expanding blood volume with IV fluid support
  2. thoracocentesis for air/fluid
  3. supplemental O2

pulling out the object —> will cause pneumothorax, immediate packing and bandaging is recommended

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12
Q

What are the 4 major steps in wound care in patients with thoracic trauma?

A
  1. pack wound with lap sponge or huck towel
  2. seal wound with loban dressing, rectal sleeve, or saran wrap, and secure with elastikon
  3. stent bandage or tie-over
  4. tetanus toxoid
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13
Q

What are the 3 groups of medications recommended in treating penetrating thoracic wounds?

A
  1. pain control: NSAIDs (Flunixin, Phenylbutazone), opioids (morphine), intercostal nerve blocks
  2. broad-spectrum systemic antibiotics
  3. tetanus toxoid
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14
Q

What antibiotics are recommended when treating thoracic trauma to cover Gram positive, Gram negative, and anaerobic bacteria?

A

G+ - Penicillin, Cephalosporin

G- - Gentamicin

ANAEROBES - Metronidazole

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15
Q

What treatments are recommended for the pleural space in cases of penetrating wounds?

A
  • treat pneumothorax/hemothorax
  • treat thoracic contamination by placing a chest tube and flushing the chest with 5-10 L of LRS or saline SID-BID
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16
Q

What 3 sets of tubes are recommended for cases of pleural effusion or pneumothorax?

A
  1. Jackson Pratt - active (closed suction) drainage
  2. dorsal chest tube for air
  3. ventral chest tube for pleural fluid (Heimlich one way valve attached to keep air out)
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17
Q

What is prognosis of penetrating thoracic trauma?

A

good without abdominal involvement

  • guarded if septic pleuritis is present
18
Q

What is the most common cause of rib fractures in equine patients? What horses are most commonly affected?

A

severe blunt trauma

  • foals
  • neonates that underwent dystocia
19
Q

What are the most common signs of rib fractures? What rarely occurs?

A
  • increased respiratory effort
  • pain (can look like colic)
  • reluctance to move
  • swelling over injury
  • grunting and groaning on palpation
  • crepitus
  • flail chest - multiple ribs broken in two places causes suction upon exhalation = flapping

lung penetration

20
Q

How are rib fractures diagnosed?

A
  • palpation (foals)
  • ultrasonography - sensitive test for fluid, pulmonary contusions, pericardial fluid, # of ribs affected, and degree of fragmentation
  • radiographs
  • CT/MRI
21
Q

What conservative treatment is recommended for rib fractures?

A
  • multimodal pain control
  • restricted exercise
22
Q

When is surgery recommended for rib fractures? What is recommended?

A

foals with axially displaced fractures, multiple fractures, or internal injuries

internal fixation with nylon suture or cable ties or plating, bridging and cerclage

23
Q

What is prognosis of rib fractures like?

A

good to excellent without internal injuries

24
Q

What causes pneumothorax? What are 4 signs?

A

disruption of the thoracic cavity causes a loss of negative pressure due to air entering the pleural space

  1. increased respiratory effort and rate
  2. dyspnea
  3. cyanotic MM
  4. distress
25
Q

What 4 wounds commonly cause pneumothorax?

A
  1. penetrating wounds
  2. axillary wounds (SQ emphysema!)*
  3. tracheal wounds*
  4. esophageal wounds*
  • = pneumomediastinum
26
Q

What are 4 signs of pneumothorax on radiographs?

A
  1. collapsed lung
  2. increased detail in the dorsal lung field
  3. lung displaced ventrally and cranially (G)
  4. free air between diaphragm and lung (B)
27
Q

What sign is indicative of pneumothorax on ultrasound?

A

glide sign

  • normal = visualize pleural surface moving with inspiration and expiration
  • pneumothorax = no movement, just side to side
28
Q

What 3 treatments are recommended for pneumothorax?

A
  1. seal defect
  2. dorsal and caudal thoracocentesis - evacuates air from the thorax with teat cannula and suction or indwelling dorsal chest tube with a Heimlich valve
  3. supplemental oxygen
29
Q

What is prognosis of pneumothorax like?

A

good with uncomplicated cases

  • poor with traumatic wounds and other confounding factors
30
Q

What are 2 common causes of hemothorax? What are the most common clinical signs?

A
  1. trauma
  2. damage to heart and/or pulmonary or intercostal vessels
  • tachypnea
  • dyspnea
  • pale MM
  • hemorrhagic shock
31
Q

What are 4 ways to diagnose hemothorax?

A
  1. clinical signs
  2. auscultation - decreased lung sounds ventrally
  3. ultrasound - fluid between body wall and lung looks Starry Night due to increased cellularity of the fluid (hyperechoic)
  4. thoracocentesis - teat cannula in the cranioventral
32
Q

What are 4 aspects of conservative treatment for hemothorax?

A
  1. treat underlying cause
  2. address blood loss with transfusion
  3. pain management
  4. systemic antibiotics (blood is a good medium for bacteria!)
33
Q

How is the volume of a blood transfusion calculated?

A

BW x 0.08 x [(desired PCV - actual PCV)/donor PCV]

34
Q

How is it determined if a hemothorax should be drained?

A
  • dyspneic = YES; aseptic prep, intermittent vs. indwelling
  • no dyspnea = NO; pressure may be providing hemostasis, pleura can autotransfuse up to 75% of RBCs by 72 hours
35
Q

What is the prognosis of hemothorax like?

A

fair to good if sepsis does not develop (risk of pleural adhesions)

  • guarded if sepsis develops
36
Q

What are 3 indications for thoracoscopy?

A
  1. exploration - penetrating wound, neoplasia, diaphragmatic hernia, pleural effusion of unknown origin, assist thoracotomy
  2. transection of pleural adhesions
  3. guided pulmonary biopsy
37
Q

What are some indications for lung biopsies? What is the best option for technique? What must be performed after?

A

NOT COMMON - neoplastic or granulomatous masses

thoracoscopy-guided

must seal lung to prevent closed pneumothorax - Ligasure, laparoscopic staplers, pre-tied ligature

38
Q

What are 3 indications for a thoracotomy and rib resection?

A
  1. refractory pleuropneumonia
  2. lung abscess
  3. chronic pleural effusion
39
Q

What are 4 purposes of performing a thoracotomy and rib resection?

A
  1. establish drainage
  2. removal of infected tissues
  3. lavage of affected tissues
  4. reduce pleural adhesions
40
Q

How is the horse set up for thoracotomy and rib resection? What are the 3 steps?

A

standing - horses can tolerate pneumothorax, use U/S to determine proper location

  1. crease and opening in the body wall
  2. elevate the periosteum
  3. use OB wire or oscillating saw to cut into and remove 20-25 cm of ribs

Large Animal Surgery (32 decks)

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