Ch 85 - Diaphragmatic Hernias Flashcards

1
Q

What are the three muscular components of the diaphragm?
How much of the diaphragm is composed of the central tendinous portion?

A
  • Pars lumbaris (right and left crus)
  • Pars costalis
  • Pars sternalis

Central tendinous portion approx 21% of surface area

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2
Q

Which crus is larger?
Where do they attach?

A

Right crus is significantly larger
Attach from a bifurcate tendon arising from bodies of 3rd and 4th lumbar vertrbrae medial to psoas minor muscle

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3
Q

Where do the splanchnic nerves and sympathetic trunk pass through the diaphragm?

A

Between the lateral portion of the crus and the 13th rib on each side

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4
Q

What are the three major opening of the diaphragm and what passes through each?

A

Caval foramen
- Caudal vena cava (adventitia fuses with central tendon with no extra space around cave)

Oesophageal hiatus
- Oesophagus and its blood supply
- Dorsal and ventral vagal trunks

Aortic hiatus
- Aorta
- Azygous and hemiazygous veins
- Lumbar cistern of thoracic duct

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5
Q

What are the foramina of Morgagni?

A

Minor opening between the costal and sternal attachments of the diaphragm which allow the egress of the cranial epigastric arteries (termination of internal thoracic arteries)
Herniation through these openings is known as a retrosternal or Morgagni hernia

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6
Q

What is the major source of lymphatic drainage from the peritoneal cavity?

A

Stomata within the diaphragmatic peritoneum
Drains to sternal LNs

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7
Q

Where do the phrenic nerves arise?

A
  • Dogs: 5th, 6th and 7th cervical nerves
  • Cats: 4th, 5th and 6th cervical nerves
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8
Q

List the surgical approached for Diaphragmatic hernia repair

A
  • Midling coeliotomy
  • Median sternotomy
  • Minimally invasive via resection of the xyphoid
  • 9th intercostal thoracotomy
  • Laparoscopic or thoracoscopic
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9
Q

What percentage of Diaphragmatic hernias are traumatic?

A

85%

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10
Q

What is the normal pleuro-peritoneal pressure gradient during relaxed inspiration?
What does this increase to during maximal inspiration?

A
  • Normal 7-20cm H2O
  • Maximal inspiration 100mm H2O
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11
Q

What causes an indirect traumatic Diaphragmatic hernia?

A

Increase in intra-abdominal pressure with an open glottis

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12
Q

What are the most common forms of diaphragmatic tears in dogs and cats?

A

Dogs:
- 40% circumferential
- 40% radial
- 20% combination

Cats:
- 59% circumferential
- 18% radial

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13
Q

What is said to be normally resident in healthy liver which can proliferate when hepatic blood supply is curtailed?

A

Clostridia-like anaerobic bacteria

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14
Q

What are normal pressures within the hepatic venous system?
What pressure is required for hepatic venous congenstion?

A
  • Portain vein 8-12 mmHg
  • Intrahepatic sinuses 3-4 mmHg
  • Hepatic veins and Caudal vena cava 0.5-1 mmHg

If hepatic venous or caudal vena cava pressure increases to 0.85 mmHg beyond intrahepatic sinusoidal pressure, involved liver lobes become congested

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15
Q

What is the normal negative intrapleural pressure?

A

0.5-1 mmHg

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16
Q

How do the crura appear in each lateral radiograph?

A
  • Parallel in right lateral
  • Cross over/Y shaped in left lateral
17
Q

What additional radiograph view can be performed in an attempt to diagnose a Diaphragmatic hernia?

A

Erect VD view

18
Q

What contrast studies have been reported for Diaphragmatic hernia diagnosis?

A
  • Barium swallow study
  • Pneumoperitoneography
  • Postivie-contrast pleurography
  • Portography
  • Cholecystography
  • Angiography

If the hernia is plugged by viscers, false-negative can result

19
Q

What is the accuracy of ultrasound for the diagnosis of Diaphragmatic Hernia?

A

93%

20
Q

What inspiratory pressure should be avoided during ventilation for a Diaphragmatic hernia?

A
  • Avoid ventilation pressures over 20 cmH2O
21
Q

How does laparoscopic stapling of the diaphragm compare to open suturing?

A

Laparoscopic stapling is inferior

22
Q

List some alternative methods of closure of a Diaphragmatic hernia

A
  • Omentum
  • Muscle (transverse abdominis, rectus abdominis, latissimus dorsi)
  • Liver
  • Fascia
  • Collagenous xenographs
  • Polypropylene mesh
  • Silicon rubber sheeting
23
Q

What is the Valsalva effect?

A

A dangerous reduction in venous return due to unduly prolonged expansion of the lungs while suturing the diaphragm

24
Q

What are potential effects of overinflation of traumatised lungs?

A

Rupture of pulmonary parenchyma:
- Intrapulmonary haemorrhage
- Pulmonary oedema
- Pneumothorax

25
Q

Are ABx indiacted after Diaphragmatic hernia surgery?

A

Only if the liver has been herniated or injured or a hollow abdominal viscus was perforated

26
Q

What is reexpansion pulmonary oedema?

A

An inflammatroy response to lung expansion that causes increased capillary permeability
Presumable due to expansion-related mechanical injury to alveolar capillary membrane and reperfusion injury

27
Q

List potential causes of post-op pneumothorax

A
  • Handling of the lungs during surgery
  • Damage during break down of adhesions
  • Reinflation injury
28
Q

List potential effects of abdominal compartment syndrome

A
  • Decreased renal function
  • Hypotension (decreased Cardiac Output)
  • Hypoxia (reduced ventilation and lung compliance + V/Q mismatch)
  • Visceral hypoperfusion
  • Acidosis
  • Increased ICP
29
Q

How can intra-abdominal pressure be measured?
What is considered normal?

A

Can be measures with an indwelling urinary catheter
- IAP 5-10 mmHg - monitored and adequately hydrated
- 11-20 mmHg - Medical treatments instituted
- Over 20 - Surgical decompression

30
Q

What are the medical and surgical options for abdominal compartment syndrome?

A

Medical
- Analgesics
- Evacuation of intraperitoneal contents (fluid/air)
- Evaculation of intraluminal contents (urine, gastric air)

Surgical
- Surgical mesh
- Removal of spleen
- Advancement of diaphragm
- Relaxing incisions in external rectus sheath
- Leave linea unapposed and temporary open abdomen management

31
Q

What is the prognosis for traumatic Diaphragmatic hernias?

A
  • Approx 15% die before arriving to hospital
  • Survival to discharge 82-89%
32
Q

What is the cause of a congenital pleuroperitoneal hernia?

A

Incomplete development or failure of fusion of the pleuroperitoneal membrane across the pleuroperitoneal canal

Results in absense of intermediated part of left lumbar crus (1-2cm defect) or absense of both crura and part of central tendon (large defect)

33
Q

What is the cause of a congenital peritoneopericardial diaphragmatic hernia?

A

Abnormal development of the transverse septum resulting in either a gap in the ventral diaphragm or an unusually thin ventral diaphragm which ruptures

34
Q

What other abnormalities can be seen with PPDH?

A
  • Sternal defects
  • Cranial ventral abdominal wall hernia
  • Umbilical hernia
  • Abnormal swirling of hair in sternal region
  • Intracardiac defects
  • Pulmonary vascular disease
35
Q

How can a large PPDH defects be closed if not enough tissue is present?

A

Transection of the pericardium cranial to its attachement to the diaphragm and used as a flap or free graft

36
Q

What is the prognosis for PPHD?

A
  • Successful in 86%
  • Mortality rate 8.8%
37
Q

What is diaphragmatic eventration?

A

Not a true hernia
Elevation of the dome of the diaphragm into the thoracic cavity. Can be congenital or acquired after phrenic nerve disease/injury

38
Q

What are the three major opening of the diaphragm and what passes through each?

A

Caval foramen
- Caudal vena cava (adventitia fuses with central tendon with no extra space around cave)

Oesophageal hiatus
- Oesophagus and its blood supply
- Dorsal and ventral vagal trunks

Aortic hiatus
- Aorta
- Azygous and hemiazygous veins
- Lumbar cistern of thoracic duct