Diaphragmatic hernias Flashcards
According to Morgan 2020 in Vet Surg, what were 3 factors likely to result in surgical rather than conservative management of PPDH? What was the recurrence rate after surgical treatment?
Younger patient, sexually intact, clinical signs from PPDH and other congenital abnormalities.
Recurrence rate was 0%.
41% complication rate, most low grade.
Long MST for both conservatively and surgically treated patients.
In a study by Mayhew 2021 in Vet Surg did laparoscopic treatment for sliding hiatal hernia result in improvements in gastroesophageal reflux and hiatal hernia post-operative?
Yes, improvements in severity of GER and SHH were observed (no improvement in frequency).
Decreased regurgitation was also noted by owners based on CDAT questionnaire.
In a study by Mayhew 2023 in Vet Surg, did BOAS surgery result in an improvement in owner perceived regurgitation? Did the same apply for videofluorscopic studies?
Following BOAS surgery owners perceived an improvement in regurgitation after eating and during increased activity/exercise.
On blinded videofluoroscopic assessment there was no improvement in GER or SHH frequency or severity.
Label the following image from Hosgood 2021 in JAVMA describing circumferential hiatal rim reconstruction combined with esophagopexy for treatment of hiatal hernia.
In a study by Singh 2024 in JAVMA, what was the rate of pneumothorax in patients undergoing laparoscopic correction of sliding hiatal hernia?
56% (conversion to open in 22% of dogs).
Dogs owners perceived an improvement in regurgitation after eating and excitement post-op.
In a study by Seibert 2021 in JAVMA, what histopathologic condition was strongly associated with the presence of a congenital PPDH in dogs and cats?
Ductal malformations. These can impact the liver or the kidneys and can affect long term function. Liver biopsies should be performed in instances of PPDH.
Which breed might be predisposed to congenital pleuroperitoneal diaphragmatic hernia?
King charles spaniels. Normally in the left crus of the diaphragm and can cause tension gastrothorax.
In a study by Vangrinsven 2021 in JSAP, treatment of brachycephalic patients undergoing BOAS with antiacids improved what two measures post-operative?
Clinical digestive scores (measure of abnormal GI signs), and presence of gastroesophageal abnormalities (sliding hiatal hernia) during an obstruction maneouvre.
Describe the anatomy of the canine diaphragm.
What are the three major openings of the diaphragm, and what structures pass through each of them?
Caval foramen: Caudal vena cava
Esophageal hiatus: Esophagus, dorsal and ventral vagal trunks.
Aortic hiatus: Aorta, azygous, hemiazygous, lumber cistern of the thoracic duct.
The minor foramina of Morgagni are located ventrally between the sternal and costal attachments of the diaphragm, and allow for passage of the cranial epigastric arteries.
The splanchnic nerves and sympathetic trunk pass into the abdomen lateral to the crura.
What are the diaphragmatic crura?
Paired lumbar muscles that originate from the third and fourth lumbar vertebrae.
What is the name of the pleural reflection that covers the accessory lung lobe?
Plica vena cava
From which cervical nerves do the phrenic nerves arise?
C5, 6, and 7.
In cats derived from C4, 5 and 6.
What is the blood supply to the diaphragm?
Main phrenic arteries which arise from the paired phrenicoabdominal arteries and anastomose with the intercostal arteries.
Phrenic veins (cranial drains to the vena cava, caudal drain to the phrenicoabdominal).
What are some surgical approaches for repair of diaphragmatic herniation?
Ventral midline celiotomy +/- median sternotomy, ninth lateral thoracotomy (need to know the hernia side, cannot be used in cases of PPDH).
What is the proposed mechanism of injury to the diaphragm with blunt trauma?
If trauma occurs when the glottis is open there is a rapid increase in intraabdominal pressure and a sharp change to the peritoneal to pleural gradient, this results in rupture and herniation.
Are male or female dogs at greater risk for diaphragmatic herniation?
Male dogs (1-3 years of age). Trauma is the most common cause (85% of cases).
What is the typical orientation of diaphragmatic tears in dogs?
Circumferential (40%), radial (40%), combination (20%).
In cats circumferential is more common (59%) v. radial (18%).
What organ is herniated most frequently?
The liver, followed by the SI, stomach, spleen, omentum, pancreas, colon, cecum and uterus.
Can depend on the side of herniation (liver, SI and pancreas more common on the right, stomach, spleen and SI more common on the left).
What percentage of dogs with liver herniation develop hydrothorax and ascites?
30% - caused by obstruction/kinking of the caudal vena cava and hepatic veins resulting in liver congestion and production of serosanginous transudate.
Why can incarceration of the stomach in a diaphragmatic hernia be rapidly fatal?
Tympany can result in compression of the caudal vena cava.
What are some potential sequelae of diaphragmatic herniation?
Dyspnea, atelectasis, pain (chest wall contusion, rib fractures, flail chest), hypoventilation, hypoxia, VQ mismatch, shock.
Patients may be on the edge of decompensation and should be handled carefully.
What are the most common signs associated with diaphragmatic herniation?
Dyspnoea and exercise intolerance (38%).
What radiographic projection is the most useful for diagnosis of diaphragmatic herniation?
Lateral projection most useful. Partial loss of the line of diaphragm present in 66-97% of animals. May also see intrathoracic viscera, obscured cardiac shadow.
On the DV view may see lung lobe collapse and pleural fluid (20-31% of cases).
Aside from plain radiography, what other imaging techniques can be used for the diagnosis of DH?
Contrast studies (of the GI tract or pneumoperitoneography, positive contrast pleurography or peritoneography).
Ultrasonography. Doesn’t require drainage of pleural fluid for visualization.
What survival rates are reported for patients undergoing repair of diaphragmatic hernia within 24-hours?
67-94%. Higher survivals are reported in more recent literature and highlight the need for adequate stabilization prior to definitive surgical repair.
Is freshening of the edges of a chronic diaphragmatic hernia required during repair?
No, it is not essential.
What are some techniques that may be useful in repair of circumcostal diaphragmatic hernias?
Circumcostal sutures, rostral advancement of the diaphragm, transection of a rib proximally and distally with bone cutters to allow for mobilization.
What are some closure options for DH that cannot be closed primarily with sutures?
Omentum, muscle, liver, autologous fascia, polypropylene mesh, silicon rubber sheeting, porcine submucosa.
What muscle flaps have been described for large DH repair?
Transversus abdominus, rectus abdominus, latissimus dorsi.
Should be 10% larger than the defect they are going to close.
Are omental flaps strong enough for primary DH repair?
No - should be used to augment repairs, and can encourage early fibrin seal and healing. Can also be used to cover prosthetic materials.
What is the risk associated with rapid pulmonary reinflation at the time of DH repair?
Pulmonary reexpansion injury resulting in ruptured pulmonary parenchyma and intrapulmonary hemorrhage, edema, and pneumothorax. Airway pressures should not exceed 20 cmH20 and lungs that do not re-expand can be slowly re-expanded post-operatively using 10 cmH20 continuous negative intrapleural pressure.
What is the cause and treatment of reexpansion pulmonary edema?
Thought to be related to a combination of mechanical and reperfusion injury.
Treatment includes hemodynamic support, and administration of oxygen, diuretics, and bronchodilators. Some patients may require ventilation and PEEP.
What are some potential complications associated with DH repair?
Pulmonary reexpansion injury, pneumothorax, abdominal compartment syndrome.
At what pressures should abdominal compartment syndrome be treated?
11 - 20 mmHg. Can easily be measured with an indwelling urinary catheter.
If pressures exceed 20 mmHg then surgical decompression should be considered.
What are the physiologic effects of abdominal compartment syndrome?
Decreased renal function, hypotension from decreased cardiac output, hypoxia from reduced ventilation, visceral hypoperfusion, acidosis, increased ICP.
What are some ways to medically manage abdominal compartment syndrome?
Analgesia, evacuation of intraperitoneal (e.g. fluid, air) and intraluminal (e.g. urine, gastric air) contents to improve abdominal wall compliance.
What are surgical options for treatment of abdominal compartment syndrome?
Placement of a mesh, removal of organs (i.e. spleen), advancement of the diaphragm.
What are the reported recurrence rates of DH?
4% for dogs, 5% for cats.
What is pleuroperitoneal hernia?
A rare congenital hernia that usually involves a defect in the diaphragmatic cura +/- central tendon. Often associated with underdevelopment of the airways on the affected side.
What happens if the stomach becomes incarcerated in a PPDH?
Can cause cardiac tamponade due to gaseous distension.
Which organs commonly herniate in a PPDH?
Liver, spleen, falciform fat, omentum, SI, rarely the stomach.
What other congenital abnormalities might occur in conjunction with peritoneopericardial hernia?
Sternal defects, cranial midline abdominal wall hernia, umbilical hernia, intracardiac defects, pulmonary vascular disease.
Which breed of dog has been reported at increased risk of PPDH?
Weimeraners (Maine Coon cats also predisposed).
In what percentage of dogs and cats is PPDH an incidental finding?
40-50% of cats, 46% of dogs.
What imaging techniques can be used for PPDH diagnosis?
Radiography +/- contrast (used less commonly now), CT, ultrasound.
What ECG change might be present in patients with PPDH and pericardial effusion?
Electrical alternans
Should air be drained from the pericardium prior to complete closure?
Yes, otherwise can impede pulmonary expansion or even cause cardiac tamponade.
What method can be used to close large PPDH defects that cannot be closed primarily?
A pericardial flap (the pericardium is transected cranially and used as a free flap or graft).
What is the prognosis for cats with PPDH?
Surgical repair successful in 86% of cats, although complications encountered in 78%.
What is the mortality rate for dogs treated for PPDH?
9%, resolution of clinical signs seen in the majority of cases. Dogs with concomitant intracardiac defects may have a poor long term prognosis.
What are some complications associated with PPDH repair in cats?
Acute: hyperthermia, tachypnea, dyspnea, hypoventilation, acidosis, hypoxia, pneumothorax.
Delayed: incisional inflammation, hyporexia, hypoxia, pericardial effusion, hernia recurrence, pericardial cysts.
