Ruptured diaphragm

Anatomy

Diaphragm embryonically derived from four sources:
- transverse septum, mediastinum, pleuroperitoneal membranes, body wall muscles
- surrounding muscles insert into central tendon
Phrenic nerves branch just above diaphragm, vary in size and thickness,
- commonly see anterior, lateral and posteromedial (largest) branching; enter muscle and run obliquely

- then pass to undersurface of diaphragm and branch to deliver nerves to the diaphragm,
- right lateral branches are short and thick and pass posterior to cava
- left lateral branches are long and thin and head toward left hiatal margin

Epidemiology

3-4% of major blunt abdo trauma, but only 25% diagnosed on initial CXR

Penetrating injury

· Penetrating injuries: any penetrating injury below the level of 4^th rib or below the line of nipple is associated with risk of diaphragmatic rupture.

· Stab: 15% risk of abdominal visceral involvement; GSW: 45% risk of abdominal visceral involvement

· Penetrating injury has small holes
Associated with penetrating injury to any other nearby structures

· 50% have a normal CXR on presentation

· CT scan is not reliable unless there is obvious herniation of abdominal viscera into chest

For a patient with penetrating thoracic injury use DPL:

· Positive: DPL fluid comes out of chest, RBC count of >10,000 mm³ is positive  - laparotomy

· Equivocal: RBC count <10,000 and >1000: thoracoscopy or laparoscopy

· Negative: RBC count <1000/mm³

· In situation where not clinically apparent, not an emergency

· MR scanning probably best test @ later date

· Important to detect small diaphragmatic lacerations as herniation carries risk of bowel strangulation.

Blunt trauma

· Usually ruptures through the vertebrocostal triangle where the lateral arcuate ligament does not reach the 12^th rib.

· Less common for late presentations.
Associated with other injuries:
- pulmonary contusion, rib #, thoracic trauma, spleen, liver, pancreas injury

Incidence of intestinal strangulation in these lesions is up to 20%
- during respiration, intrapleural pressure fluctuates from -5 to -10, intra-abdominal pressure from +2 to +10
--> hence strong pressure gradient promotes herniation

Grading

I Contusion
II Laceration <2cm
III Laceration 2-10cm
IV Laceration >10cm with little tissue loss (<2.5cm2)

V Laceration with tissue loss >2.5cm2

Clinical Manifestations

Include audible bowel sounds in lower chest
- unilateral absence of breath sounds, respiratory distress and scaphoid abdomen
But typically actually nothing much in acute setting ~50%

Early CXR often misses it (30-60% on left, 15% on right where liver herniates)

In a ventilated patient, positive pressure may reduce herniation, making detection difficult
CT has a high sensitivity (70%+) and excellent specificity.
- may show the defect, or intrathoracic abdominal contents
Difficult to detect on thoracic trauma USS

Repair

1. Avoid entrapment of nerves as described above, if at all possible
- may be difficult with radial injuries at central tendon, vena cava foramen or esophageal hiatus.

2. Conduct normal truma laparotomy evaluating for concomitant injuries, priorities being haemorrhage and contamination control

3. Carefully reduce any contained herniation contents
- may need to pass a catheter alongside the contents to remove the vacuum effect
- may need to extend the phrenotomy

4. Exposure
- may need to divide the lienophrenic ligament and splenic flexure inferiorly to expose the left diaphgram
--> moves spleen stomach, colon away, using hand to push down.
- mobilise left lateral segments of the liver medially to expose the central tendon and gastric hiatus
- right side buttressed by the lier; mobilisation of falciform will aid inspection, triangular ligament only taken down if injury clear
- and division of the right triangular ligament and posterior hepatic attachment will help liver be pulled inferiorly providin exposure to the right diaphragm (and IVC, adrenal, kidney).

5. Repair
- Allis clamps used to siolate the edges of the tear and enable manipulation
- Close with interrupted 0 nylon figure 8 stitches, including viable dissue and excluding / (debriding first) nonviable tissue
- Tail of the previous suture left long as a handle.

If repair is tenuous?
Pledgets and horizontal mattress sutures can help.

Removing pneumothorax

Pass a 24Fr drain through the last stitch and aspirate prior to pulling tight.
- any doubt, place a chest drain

Large wound / defect
Place a bridging nonporous biological mesh material e.g. pig dermis product (or GoreTex)

Avulsed from ribs
Reattach 1-2 ribs higher to repair without tension.