Overview

The diaphragm is an all-important physical barrier between the thoracic and abdominal cavities. The diaphragm functions to not only separate the cavities, but also to assist ventilation and allow for important structures such as the aorta, caudal vena cava, thoracic duct, right azygous vein, and esophagus to pass between both cavities.

From Clinicians Brief: Surgical Repair of Traumatic Diaphragmatic Hernia

The colon and spleen can be seen herniating through the diaphragm. No small intestine, stomach, or liver can be seen in the abdomen.

Diaphragmatic hernias can be either congenital or acquired secondary to blunt force trauma such as vehicular trauma, falling from great heights, or a blow to the abdomen. Trauma is by far the most common cause of diaphragmatic hernias with reported ranges between 75-85% of diaphragmatic hernias. True congenital diaphragmatic hernias are much less frequent and the most common subtype of congenital hernia is a peritoneal-pericardial diaphragmatic hernia (PPDH), or a continuation between the pericardium of the heart and the diaphragm.

Signs and symptoms

The signs can be variable, depending on the cause of the hernia, concurrent injuries, and what abdominal organs are herniating into the chest. Signs associated with an acute diaphragmatic hernia are usually related to difficulty expanding the lungs with the additional contents in the chest. Signs observed include:

• difficulty breathing
• rapid, shallow breathing pattern
• exercise intolerance
• abnormal breathing posture with extended head and neck

In some animals the initial tear is small, or the injury is well-tolerated so that the hernia is not recognized acutely. In these patients the abdominal organs may herniate in and out of the chest or may become adhered to the diaphragm or chest pleura. Chronic vomiting or diarrhea or an elevation in liver enzymes can be the primary signs in these types of cases. Amazingly, over time organ attachments can become very stretched and sometimes the entire small intestine, spleen, liver and gall bladder can even be found herniated into the chest!

Radiographs courtesy of Dr. Jasmine Hoveland, posted in VetHive. 2 year old MN DSH with chronic exercise intolerance and coughing. On the lateral projection only the kidneys and colon can be seen in the abdomen and all other (mobile) organs are herniated into the chest!

Physical exam

Examination may be normal but auscultation often reveals muffled heart sounds. When intestines are herniated, borborygmus may be heard. The abdomen may have decreased contents on palpation.

Diagnostics

Concurrent orthopedic (14-33%) and soft tissue (27-41%) injuries are commonly diagnosed along with diaphragmatic hernia. It’s important to perform a thorough physical exam, minimum database, and thoracic and abdominal orthogonal radiographs in patients that have sustained trauma. The diagnosis of diaphragmatic hernia is most commonly made using these films. Ultrasound can be very useful as well.

Timing of surgery

A patient with an acute traumatic diaphragmatic hernia should be operated as soon as the patient is hemodynamically stable (treat the shock first) and other more life-threatening injuries are managed. There may be concurrent lung contusions or pleural effusion that would make reexpansion pulmonary edema more likely following removal of the abdominal organs from the chest. Fluid and oxygen therapy should be instituted in these patients as well as chest taps as needed. When the stomach herniates into the chest, this is a surgical emergency because the stomach can still fill with air but will often have an outflow obstruction. An orogastric tube, nasogastric tube, or trocharization can be performed prior to surgery to provide decompression of the stomach.

Surgery

An abbreviated account of surgical management is bullet pointed here. This is a procedure that requires a command of the regional anatomy, manual ventilation, and often intensive aftercare. An advanced surgical textbook is highly recommended to guide perioperative care 😊

• Be prepared to manually ventilate if the practice does not have a mechanical ventilator.
• Perioperative IV antibiotics such as cefazolin is given at induction and every 90 minutes during surgery at 22mg/kg.
• Anesthetic protocols should be cardiac sparing. A pure mu agonist or buprenorphine is recommended for pain management.
• A midline abdominal approach is performed.
• It may be necessary to open the hernia up further in order to reduce the contents.  Always direct this opening more ventrally to avoid important structures like the vena cava and aorta.
• The abdominal organs can be adhered to the diaphragm in more chronic cases and these adhesions require blunt or sharp dissection to be reduced.
• Place patient in a reverse Trendelenburg position (head tilted up) to move the organs more caudally and/or use an assistant to retract.
• There is no need to trim the edges of the rent and it can actually make closure more difficult.
• Close the rent with 0 to 3-0 absorbable monofilament suture such as PDS. Start the suture line dorsally (hardest area to reach) and work ventrally in a continuous or interrupted pattern.
• The air in the chest will need to be evacuated and this can be done through a traditional chest tube or a tube placed through the diaphragm and exiting the abdomen. This tube can be pulled once the patient is no longer producing air and fluid from the tube.

Aftercare

Post-op care incudes ongoing fluid therapy, pain management with opioids and nsaids or gabapentin, and supportive care. The patients may need oxygen therapy and will require close monitoring for respiratory status, given the tendency for development of hypoventilation, hypoxia, and respiratory acidosis. Overnight care in a 24 hour facility is highly recommended when possible.

Prognosis

Survival to discharge following diaphragmatic hernia surgery ranges from 82-89% of patients. Major complications are reported in up to 50% of patients and these include pneumothorax, organ failure, post inflation pulmonary edema, cardiac arrhythmias, ascites, gastric ulceration, esophagitis, megaesophagus, hiatal hernia, and recurrence of the diaphragmatic hernia.

References and recommended reading

Tobias, K. M. (2017). Veterinary surgery: Small animal expert consult - 2-volume set. Elsevier - Health Sciences Div.

Monnet, E. (2013). Small animal soft tissue surgery. John Wiley & Sons.

Lopez DJ, Singh A. Surgical repair of traumatic diaphragmatic hernia. Clinicians Brief June 2017.

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About the Guide: Jill Luther, DVM, MS, DACVS (Surgery)

Dr. Jill Luther earned her board certification in small animal surgery in 2010. She spent 4 years in private practice, 8 years as academic faculty, and in 2021 started Heartland Veterinary Surgery to provide mobile soft tissue consultation and teaching. Her greatest strength in teaching lies in the applied, practical application of surgery. Dr. Luther is an ambassador for female specialists refusing to accept the status quo.