Diaphragmatic Hernias Flashcards
Describe the anatomy of the diaphragm
The diaphragm works as ventilation and assist in the movement of lymphatic vessels. The caval foramen houses the caudal vena cava. The esophageal hiatus houses the the esophagus and vagus nerve trunks. The aortic hiatus houses the aorta, thoracic duct and right azygous vein.
What is the most common cause of diaphragmatic hernia?
Vehicular trauma
Diaphragmatic hernia pathophysiology
Indirect pressure -> increase intraabdominal pressure
- Lost of diaphragmatic function
- pneumo-, hemo-, thorax; pleural effusion
- herniated viscera
- pulmonary or caval compression
- chest wall contusion
- flail chest: fix of ribs so that area is now mobile and moves independently
Describe the types of tears within the diaphragm, where are they most common?
Radial: along fiber orientation
Circumferential: at rib attachments
Or combined
Its rare to see a tears within the central tendon, its usually the peripheral muscles
What are clinical signs of diaphragmatic hernias?
Dyspnea, hypovolemic shock in acute trauma, GI signs, Lethargy, restlessness, trouble lying down or no clinical signs
To dx diaphragmatic hernias you can take __ rads and __ of cases will have loss of the normal diaphragmatic outline. There may also be abdominal viscera in the thorax, obscured or displaced cardiac shadow.
To dx diaphragmatic hernias you can take lateral rads and 66-97% of cases will have loss of the normal diaphragmatic outline. There may also be abdominal viscera in the thorax, obscured or displaced cardiac shadow.
Radiographs of a diaphragmatic hernia
Loss of normal diaphragmatic outline in 60-80
5, obscured displaced cardiac silhouette and cranial pylorus/duodenum
Ultrasound for diaphragmatic hernias is __ accurate and helpful with __ effusion
Ultrasound for diaphragmatic hernias is 93% accurate and helpful with pleural effusion
In what scenarios should you wait for surgery in diaphragmatic hernia cases?
When they are not stable for anesthesia OR when they have pulmonary contusions because they won’t respond to oxygen if they have then. In these cases you can wait 3-5 days for them to improve and it does not increase morbidity rate
Reasons to not wait for surgery of diaphragmatic hernias
Persistent deterioration, gastric herniating with tympani, persistent abdominal pain (intestinal strangulation)
Anesthesia interventions for diaphragmatic hernia sx
Tilt the table so that the head and thorax are elevated, preoxygenate. Rapidly induce/intubate and keep sternal. Keep positive pressure ventilation while avoiding high inspiratory pressure (>20), IV fluids and ECG monitoring
Surgery for diaphragmatic hernia
- Ventral midline celiotomy
- Abdominal explore
- Evaluate viable organs
- Debride defect edges (if covered in fibrin)
- Place thoracostomy tube
- Lavage after you’ve replaced the organs and started the closure
- Absorbable monofilament suture in simple continuous or tension relieving patterns
The thoracostomy tube goes through the __and out __
The thoracostomy tube goes through the diaphragm and out laterally
Considerations for chronic hernias
- Mature adhesions and/or fibrosis
- Reperfusion injury
- Re-expansion injury
- Re expansion pulmonary edema
- Loss of domain
- Primary apposition not always possible
Adhesions and/or fibrosis for diaphragmatic hernias
- between herniate organs and thoracic wall and/or lung
- adhesions < 7-14 days old should not pose dissection challenges
- possible complications of chronic adhesions are hemorrhage and pulmonary air leak
- potential organ removal
Reperfusion injury of diaphragmatic hernia
Vascular obstruction -> anaerobic metabolism
Acute relief of obstruction
1. Free radical oxygen species
2. Inflammatory cytokines
3. SIRS
Treatment goals is removal without obstruction relief
Reexpansion pulmonary edema is an issue in __ with chronically __ lungs where acute re expansion results in reperfusion injury and pulmonary edema.
Reexpansion pulmonary edema is an issue in cats with chronically atelectatic lungs where acute re expansion results in reperfusion injury and pulmonary edema.
How to prevent re expansion pulmonary edema
-Keep airway pressure <20 cm H20
- do not force them to re inflate or completely re establish pressure
- reduce pneumo thorax slowly over 8-10 hours
Loss of domain of diaphragmatic hernias
- chronic absence of viscera from abdomen
- closure risks excessive intra abdominal pressure
- crowding -> vascular compromise of viscera
Surgical options are organ removal, diaphragmatic advancement or abdominal wall reconstruction
Alternative methods of closure for diaphragmatic hernias
- Muscle flaps (TA or RA)
- Auto genius grafts (omentum or fascia)
- Exogenous grafts (SIS, silicone or mesh)
Prognosis of diaphragmatic hernias
15% mortality pre surgery and perioperative mortality rate 10-30%, but excellent prognosis if they survive the perioperative period
Stabilize and get them through surgery = a good chance!
