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Small Animal Surgical Diseases > Diaphragmatic Hernia > Flashcards

Diaphragmatic Hernia Flashcards

1
Q

What are the 2 types of diaphragmatic hernias?

A
  1. traumatic – acute (<14d) or chronic (>14d)
  2. congenital – pleuroperitoneal or peritoneocardial
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2
Q

what are the various foramina of the diaphragm?

A
  1. caval foramen (for vena cava)
  2. esophageal hiatus (for esophagus, vagal trunks)
  3. aortic hiatus (for aorta, azygos and hemiazygos veins, and the lumbar cistern)
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3
Q

what are the 3 tendinous parts of the diaphragm?

A
  • central tendon
  • right crus
  • left crus
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4
Q

what are the 3 muscular parts of the diaphragm?

A
  • pars sternalis
  • pars costalis
  • pars lumbalis
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5
Q

T/F: diaphragmatic tears are named based on size

A

false – based on location. (circumferential, radial, combined)

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6
Q

what is the MOST common source of traumatic diaphragmatic hernias?

A

vehicular trauma / motor vehicle accidents

first thing to do for these patients is to look at the big picture and stabilize them. They can have other concurrent injuries (pulmonary contusions, rib fractures, etc.)

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7
Q

what 3 iatrogenic events can also lead to traumatic diaphragmatic hernias?

A
  1. thoracocentesis
  2. inadvertent extension of midline celiotomy incision
  3. too enthusiastic when clearing falciform fat during surgery
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8
Q

T/F: bilateral or multiple tears in traumatic diaphragmatic hernias is common

A

false – uncommon only 15%

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9
Q

what is the most common organ to herniate in cases of diaphragmatic hernias?

A

liver

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10
Q

which diaphragmatic muscle rupture most commonly?

A

pars costalis

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11
Q

what are clinical signs of diaphragmatic hernia?

A
  1. dyspnea***
  2. hypovolemic shock (acute trauma)
  3. GI signs – gagging, vomiting (chronic cases)
  4. lethargy
  5. difficulty laying down (d/t abdominal pain)

or no clinical signs

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12
Q

why does diaphragmatic hernia cause problems in the patient? (3 reasons)

A
  1. If the diaphragm has hole, it has lost its function of maintaining a negative pressure in the thorax.
    Pneumothorax, hemothorax, and pleural effusions can occur.
    Accumulation of air or fluid in the thoracic cavity prevents the lungs from inflating.
  2. When/if organs herniate into the thoracic cavity, they serve as space-occupiers and can lead to negative respiratory effects, as well as be at higher risk for visceral strangulation.
  3. Patients with DHs can suffer from pulmonary and caval compression, decreasing venous return, as well as chest well contusions leading to flail chest.
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13
Q

what physical exam findings may be apparent with a diaphragmtic hernia?

A
  1. muffled heart and lung sounds
  2. thoracic borborygmi (not reliable)
  3. tucked up abdomen (chronic hernias, discomfort)

or the PE can be normal!

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14
Q

what diagnostics are MOST useful and readily available for diagnosing diaphragmatic hernia?

A

U/S and radiographs

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15
Q

which radiograph is BEST to diagnose DH and what would you expect to see?

A

LATERAL thoracic radiograph
expect loss of normal diaphragmatic outline, possibly abdominal viscera in the thorax, obscured/displaced cardiac shadows, or excessively cranial pylorus/duodenum (bc when liver herniates and pulls those organs with it)

Avoid restraining and causing stress, and avoid over-sedation.

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16
Q

T/F: contrast studies and CT scans are very helpful in diagnosing diaphragmatic hernias and are used often.

A

false – they are rarely indicated.

17
Q

What is MOST important in the treatment of DH prior to initiating any surgical procedures?

A

stabilize the patient in order to reduce anesthetic risks.

treat shock, analgesia, oxygen supplementation, +/- thoracocentesis, +/- gastric decompression.

18
Q

what are the 3 big anesthetic considerations for patients needing surgical correction of a diaphragmatic hernia?

A
  1. Poor ventilation (there is viscera or fluid in the thorax causing pulmonary compression and lack of a functional diaphragm keeping negative pressure in thorax)
  2. Poor gas exchange – pulmonary contusions, V/Q mismatch
  3. Poor perfusion – shock, caval compression

wait a few days (if possible), then perform surgery.

19
Q

Generally, when should you perform surgery to correct DH?

A

As soon as possible, but ensuring the patient is stable FIRST and can tolerate anesthesia.
If you can take time to improve their status, thats the best plan.

19
Q

T/F: you should tilt the head of the surgery table down to decrease the risk of aspiration during surgical correction of DH

A

false – tilt the head and thorax UP so that the viscera are not constantly falling back into the thorax.

19
Q

What are 3 reasons to NOT wait to stabilize your patient prior to correcting a DH?

A
  1. peristent deterioration of patient despite appropriate management
  2. gastric herniation with tympany
  3. persistent abdominal pain (indicates intestinal strangulation)
20
Q

Why do you need to do positive pressure ventilation when surgically correcting a DH?

A

the injured diaphragm is no longer able to contribute to the normal negative pressure of the thoracic cavity.
You must help them inflate their lungs.

Ensure NOT to go to high inspiratory pressures (>20 cm H2O) because the lungs have not been well-inflated for some time and you can cause reinflation injury.

21
Q

Why should you be prepared to enlarge the diaphragmatic defect when surgically correcting a DH?

A

Herniated organs can swell/become inflamed and no longer fit back through the defect. You do not want to pull hard on the organs or force them through, so just enlarge the defect a little.

22
Q

what suture and pattern should you use to close a diaphragmatic defect?

A
  • absorbable monofilament
  • simple continuous pattern*
23
Q

What are some things you need to consider in cases of chronic hernias?

A
  • mature adhesions and fibrosis
  • reperfusion injury
  • re-expansion pulmonary edema
  • loss of domain
  • primary apposition may not be possible (chronic cases)
24
Q

T/F: adhesions greater than 30 days old should not pose dissection challenges during surgical correction of DH

A

false – if less than 7-14 days old should not pose dissection challenges during surgical correction of DH

25
Q

what could happen if you dissect chronic adhesions that formed after DH?

A

hemorrhage
pulmonary air leak

26
Q

what causes reperfusion injury?

A

when there is a vascular obstruction then anaerobic metabolism takes place. When you quickly relieve the obstruction, all of the free oxygen radicals and inflammatory cytokines are released leading to systemic inflammatory response syndrome (SIRS)

that is why it is so important to RESECT tissues and organs WITHOUT relieving the obstruction.

27
Q

what causes re-expansion pulmonary edema?

A

chronically atelectatic lungs that are quickly reexpanded are involved in reperfusion injury and pulmonary edema.

28
Q

how can you prevent re-expansion injury?

A
  1. keep airway pressure under 20 cmH2O
  2. do not force atelectatic lung lobes to reinflate
  3. do not completely restablish negative intrathoracic pressure during closure
  4. reduce the amount of pneumothorax slowly over 8-10 hrs.
29
Q

what causes loss of domain?

A

chronic absence of viscera in the abdomen

if you force the closure, you risk excessive intra-abdominal pressure.

30
Q

what are the 3 options for working with loss of domain?

A
  1. organ ressection (start with spleen)
  2. diaphragmatic advancement
  3. abdominal wall reconstruction
31
Q

what is the prognosis for diaphragmatic hernias?

A

15% die before surgery

10-30% perioperative mortality.

prognosis is excellent if they survive the perioperative period.

32
Q

What is the method of action of indirect injury to the diaphragm?

A

acute increase in intraabdominal pressure

33
Q

what is the most common area for diaphragm injury?

A

diaphragmatic costal muscle rupture

Small Animal Surgical Diseases (20 decks)

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