Ch 85 - Diaphragmatic Hernias Flashcards
What are the three muscular components of the diaphragm?
How much of the diaphragm is composed of the central tendinous portion?
- Pars lumbaris (right and left crus)
- Pars costalis
- Pars sternalis
Central tendinous portion approx 21% of surface area
Which crus is larger?
Where do they attach?
Right crus is significantly larger
Attach from a bifurcate tendon arising from bodies of 3rd and 4th lumbar vertrbrae medial to psoas minor muscle
Where do the splanchnic nerves and sympathetic trunk pass through the diaphragm?
Between the lateral portion of the crus and the 13th rib on each side
What are the three major opening of the diaphragm and what passes through each?
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
What are the foramina of Morgagni?
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
What is the major source of lymphatic drainage from the peritoneal cavity?
Stomata within the diaphragmatic peritoneum
Drains to sternal LNs
Where do the phrenic nerves arise?
- Dogs: 5th, 6th and 7th cervical nerves
- Cats: 4th, 5th and 6th cervical nerves
List the surgical approached for Diaphragmatic hernia repair
- Midling coeliotomy
- Median sternotomy
- Minimally invasive via resection of the xyphoid
- 9th intercostal thoracotomy
- Laparoscopic or thoracoscopic
What percentage of Diaphragmatic hernias are traumatic?
85%
What is the normal pleuro-peritoneal pressure gradient during relaxed inspiration?
What does this increase to during maximal inspiration?
- Normal 7-20cm H2O
- Maximal inspiration 100mm H2O
What causes an indirect traumatic Diaphragmatic hernia?
Increase in intra-abdominal pressure with an open glottis
What are the most common forms of diaphragmatic tears in dogs and cats?
Dogs:
- 40% circumferential
- 40% radial
- 20% combination
Cats:
- 59% circumferential
- 18% radial
What is said to be normally resident in healthy liver which can proliferate when hepatic blood supply is curtailed?
Clostridia-like anaerobic bacteria
What are normal pressures within the hepatic venous system?
What pressure is required for hepatic venous congenstion?
- 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
What is the normal negative intrapleural pressure?
0.5-1 mmHg