Page 486 - WSAVA2018
P. 486

 25-28 September, 2018 | Singapore
have significant thoracic adhesions. Acute herniations surgically managed within 10 days will not have had time to develop adhesions and reduction is often straight forward. However even acute hernias can be difficult due to congested and friable splenic or hepatic tissue. Torsed vascular pedicles should be noted and de-rotated under controlled circumstances as appropriate or excised if
this appears safer. In cases of chronic herniation with extensive adhesions visualization of structures from the thoracic cavity can improve safety. The surgeon should be prepared to perform a caudal sternotomy as required.
During reduction of the hernia the free volume within the thoracic cavity will increase and available volume in the abdominal cavity will decrease. In acute herniations this is generally of less consequence. Care should be taken to evacuate the chest very slowly such that the lungs are not placed under excessive strain. Aggressive ventilation beyond 20cm of water to re-expand the lungs sound
be avoided. Negative pressure in the pleural space will facilitate re-expansion of the lungs more slowly and safely. Re-expansion injury can occur in chronic and acute cases secondary to mechanical and reperfusion injury. All efforts should be made to re-expand the lungs slowly. The increased abdominal contents may cause a ‘loss of domain’ necessitating emptying of the bladder, removal of falciform fat and omentum, and even removal of the spleen should this appear to be contributing significantly. Tension relief of the abdominal wall or an expanded closure with a graft is also a potential option. In cases with abdominal tension an indwelling urinary catheter should be placed to allow post-operative measurement of intrabdominal pressure.
The closure of the diaphragm itself can be performed with synthetic monofilament typically between 3-0 and 0 USP. Suture patterns vary but include simple interrupted, mattress, cruciate, simple continuous patterns (the
latter leaving less knot ends that could lacerate hepatic parenchyma). Suturing is generally started dorsally and completed ventrally. Prior to placing the last 1-2 sutures a chest tube can be advanced through the defect and into the thorax. This can then be used to gently remove air from the thoracic cavity with caution not to inflict excessive re-expansion trauma. This tube can then often be removed. In cases where ongoing fluid or gas accumulation are anticipated an indwelling chest tube can be placed.
Post-operative monitoring should include careful evaluation of respiration and blood gas analysis where possible. Adequate analgesia and supportive care provided, the extent of which to be determined on a case by case basis. Abdominal pressures should be below 10mmHg, with medial or surgical interventions required beyond this pressure.
Potential complications include pneumothorax, haemothorax, pulmonary re-expansion injury, or other
sequelae arising from the original trauma. Post-operative reflux and oesophageal ulceration is seen in some cases. Extended medical management for reflux can become necessary. Although the recurrence rate is generally low, the client should be instructed to monitor closely, and re-evaluation/imaging performed as needed.

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