Mathematical Model

Each organ or viscus within abdominal cavity is susceptible to penetrating injuries.⁶³ The frequency of penetrating injuries to intra-abdominal organs is related to size, location and the protection of the overlying ribs or spine.¹²

1. Stomach:

This organ is commonly affected by penetrating abdominal injuries unlike in blunt injuries because of its protection by the lower ribs.^1,6 The diagnosis can be made by attendant signs of peritoneal irritation and persistent aspiration of bloody fluid from naso-gastric tube and/or vomiting of blood.

The penetrating injuries to stomach can be either full thickness (through & through) or partial thickness. Most full thickness gastric injuries are due to penetrating trauma.¹⁸ Also these injuries can affect anterior and posterior aspects of the stomach or any portion of it.^18,23

The blood supply to the stomach is excellent and wound healing is faster.⁷ These injuries are usually debrided and sutured primarily with absorbable materials in 2 layers. Also, the defect can be closed by use of stapler.^7,30 Majority of the full thickness injuries of distal third of the stomach may require resection of that portion of it and re-establishment of gastrointestinal tract by gastrojejunostomy.^1,6 For gastro-oesophageal junction injuries, the repair can be done primarily and covered by fundic wrap or fundoplication.¹

2. Duodenum:

The duodenum is much commonly injured by penetrating abdominal missiles (75%) than in blunt abdominal trauma (25%). This is because it is mostly located in retroperitoneal region of the abdomen and protected by lower ribs. Also duodenal injuries are uncommon but are associated with a high morbidity and mortality if not identified at laparotomy.³ The extent and severity of its injuries are determined by the causative agent. High velocity bullets produce larger lacerations than stab wounds.¹⁸ The diagnosis of duodenal injuries is difficult and usually delayed. It is due to its retroperitoneal spillage of its contents, which thereafter extend into peritoneal cavity resulting in peritoneal irritation as a late sign. A high index of suscipion is important in diagnosis of its injury in upper abdominal wounds.^64,66

Duodenal injuries can be divided into 5 grades, as follows: ¹ Grade 1 - Intramural Haematoma with a less than 50%

circumference involvement.

Grade II - Haematoma greater than 50% and laceration less than 50% in circumference.

Grade III - Laceration greater than 50% in circumference (any segment) and transection of the fourth portion of the duodenum.

Grade IV - Laceration greater than 75% in circumference of second portion, transection of an intra pancreatic common bile duct (CBD)

Grade V - Duodenal devascularization or combined duodenal

& pancreatic injury.

The treatment of these injuries depends on the grade or severity of injury. For lesser grade of laceration, kocherization of duodenum and division of ligament of Treitz is done to mobilise and identify the site of injury. Thereafter, wound debridement and closure in 2 layers is performed.

The success rate is about 80% in most studies.⁶

For extensive lacerations or where there is loss of duodenal tissue, complete excision of injured portion and anastomosis or closure of both ends of duodenum and gastro-jejunostomy is done.¹⁸ For duodenal injury involving the second part , transection of intrapancreatic common bile duct (CBD) and ampulla, pancreaticoduodenectomy is carried out. If the common bile duct and ampulla are intact, the duodenal defect is closed and roux-en-Y gastro-jejunostomy is done.⁶ The most common post operative complications are leakage of anastomotic points, duodenal fistulae and intra-abdominal sepsis.

3. Small bowel injuries

Patients with small bowel injuries should have emergency laparotomy.^4,38,43 Stab wound of the abdomen with small intestinal injuries can be repaired primarily but extensive lacerations or multiple ones close together are excised and anastomosis of viable segments done.⁴ Studies have shown that most stab and gunshot wounds affecting less than 50% of bowel circumference can be repaired primarily in a transverse fashion.^6,7,43 Those with perforation or laceration larger than 50% of circumference or devascularization injuries may require resection and primary anastomosis.^4,45 Simple bowel injuries that are operated soon after the injury do well. Multiple lacerations especially those not repaired early have poor prognosis. They require longer hospital stay and rehabilitation.^7,62,67

4. Large bowel injuries

A haemodynamically unstable patient should undergo damage control surgery.^1,42 When colonic injury involves less than 50% of colonic diameter, it can be closed in a transverse fashion. Larger defects are resected and anastomosis done (with stapler TA 30–35 preferably applied across the defect).^6,

Controversy exists over primary closure of colonic injuries with either accompanying defunctioning colostomy or exteriorization of the injured part.³ It has been customary to repair left sided colonic injuries with exteriorization of part of colon or colostomy than the right sided wounds.

Several studies urged that this is not necessarily true, as colostomy formation is also associated with a higher complication rate than in all cases of wounds repaired primarily. ³ Therefore, in absence of shock, peritonitis and a major associated injury or destructive colonic injury, resection and primary anastomotic repair should be performed. The alternative being a mucous fistula or Hartman’s procedure for sigmoid and rectum.^30,60

For injuries to the right colon, a hemicolectomy and ileotransverse anastomosis should be performed. The results obtained has been satisfactory as observed by many surgeons.^3,4 Exteriorization of a colonic injury as treatment modality, appears to have few advocates.³

Rectum: Injuries to the rectum below the peritoneal reflection are an exception to the rule of penetrating abdominal injuries. They are rather treated by presacral drainage and diversion of faecal stream.¹ The outcome of rectal injuries above the peritoneal reflection may be lethal due to severe infection from bacterial contamination from faecal peritoneal soilage.^1,11,25 Usually there is associated 10% mortality.^3.30

Risk factors in colonic injuries:

These include:

1) Presence of pre-operative shock

2) Intra-peritoneal blood loss of > 1000 mls

3) More than two intra-abdominal organs injured.

4) Gross faecal contamination

5) Delay in surgery of more than 4 hours 6) Abdominal soft tissue loss

7) Additional injury to the urinary tract could result in intra-peritoneal leakage of urine.

8) High velocity missile wound 9) Bomb blast to abdomen.^6,8,15,16

SOLID ORGAN INJURIES:

A) Liver:

The liver is the most commonly injured solid organ due to penetrating trauma of the abdomen.³ The extent of its damage is dependent on the magnitude of violence.^4,9 Indeed, 80% of liver injuries are accompanied by injuries in other organs.¹

Among these penetrating injuries, knife stab wounds produce more superficial lacerations than bullet wounds. Those of bullet wounds are more ragged and produce through and through injuries of liver. The blast effect from the bullet wounds causes necrosis of large section of liver tissues and various injury types.^4,7 These liver injuries are graded as follows: ^2,6

Grade I: Subcapsular haematoma, less than 10% surface area

Laceration-capsular tear less than 1cm parenchymal depth

Grade II: Subcapsular haematoma, 10 – 50% surface area Intraparenchymal injury less than 10cm in diameter.

Laceration 1–3cm

Parenchymal depth less than 10cm.

Grade III: Subcapsular haematoma less than 50% surface area or expanding rupture of subcapsular or parenchymal

haematoma.

Intraperitoneal haematoma less than10cm or expanding laceration greater than 3cm parenchymal depth.

Grade IV: Laceration, parenchymal disruption involving 25 – 75% of hepatic tissue.

Grade V: Laceration parenchymal disruption involving greater than 75% hepatic tissue. Vascular juxta-hepatic venous injuries i.e. retrohepatic caval/central major hepatic veins.

Grade VI: Vascular hepatic avulsion.

Grades (I & II) hepatic injuries constitute 80 – 90% of all cases of stab or minor liver penetrating injuries. Grades (III–VI) injuries are regarded as severe or major injuries usually from very violent instruments or bullet wounds.⁴

The basic principles in management of hepatic injuries involve control of haemorrhage, removal of devitalized tissues and perihepatic drainage.^3,20 Any suscipion of hepatic injury is therefore an acceptable

indication for laparotomy in penetrating abdominal injury.⁴ At laparotomy the following basic operative techniques are carried out:

1. Minor liver injuries (grades I & II)

(a) Gauze packing and assessment of other viscera for any injuries.

(b) If minor bleeding persists, topical haemostats like surgicel spongostan and kaltostate may be applied.

(c) Intra-hepatic omental packing is thought to be superior to gauze packing in controlling bleeding following hepatic parenchymal debridement.^3,7,20

2. Major liver/hepatic injuries (grades III-VI) The bleeding can be arrested by:

(a) Portal triad occlusion (Pringle’s manouvre).⁶⁸ (b) Bimanual compression of injured liver tissues.

c) Aortic clamping at hiatus

d) Perihepatic packing and planned re-exploration can be a life-saving procedure. This is indicated in patients who are likely to develop hypothermia, coagulopathy and acidosis.

e) Partial hepatectomy with finger fracture: The success rate of this procedure is 87% in the treatment of liver injuries.

f) Resectional debridement: Resection is carried along lines of devitalised tissue and it prevents sepsis and bile leakage.

Usually it is performed when packing of bleeding areas in liver parenchyma is removed.

g) Other modalities of treatment include:

(i) Hepatorrhaphy – The use of horizontal mattress sutures for liver stitching for grades I – III liver injuries has shown good control of hepatic bleeding in many centres. Usually there is the risk of necrosis of normal liver tissue if the procedure is incorrectly applied.²²

ii) Selective hepatic artery ligation: It is tried when Pringle’s Manouvre, hepatorrhaphy and packing have failed to control the bleeding. If the right hepatic artery is ligated, cholecystectomy should be performed.^7,30

iii) Lobar or sublobar (anatomical) resection. There is high mortality rate > 60% associated with this technique, therefore it is discouraged.^7,69

iv) Intra-hepatic balloon tamponade.⁶⁹

v) Mesh Repair (absorbable vicryl mesh). This is costly and time consuming.^3,4

vi) Fibrin glue (fibrinogen, thrombin calcium chloride). Fibrin glue is a very useful method of controlling bleeding at raw surfaces of injured liver tissues. Also, it is an adjunct to hepatectomy and debridement.^2,6

vii) Placement of an atrio-caval shunt may be used to control retro-hepatic bleeding.^20,69,70

B) Spleen:

The spleen is one of the intra-abdominal organs most frequently involved in blunt abdominal injuries. It is also often injured in penetrating injuries of the abdomen and in thoraco-abdominal injuries.^4,22 The severity

of splenic injuries varies with various grades of injuries both in blunt and penetrating abdominal trauma.

The CT-Scan grading of splenic injuries include: ²

Grade I Subcapsular haematoma, non-expanding, less than10%

Laceration, capsular tear, non-bleeding, less than 1cm in diameter.

Grade II: Subcapsular haematoma, non-expanding, 10 –15% or intra- parenchymal, non-expanding, less than 2cm in diameter.

Grade III: Laceration, capsular tear, active bleeding haematoma, subcapsular haematoma greater than 50% or expanding or ruptured bleeding haematoma intra-parenchymal greater than 2cm in diameter.

Grade IV: Laceration, greater than 3cm parenchymal depth, haematoma, ruptured intra-parenchymal, haematoma with active bleeding Laceration involving segmental or hilar vessels producing major devascularization greater than 25% of spleen

Grade V: Laceration, completely shattered spleen. Hilar vascular injury that devascularized the spleen.²

The majority of trauma to spleen from gunshot injuries are severe (grade III – V). This is due to the blast effect impacted to the organ. The patients are usually haemodynamically unstable or in hypovolemic shock.^3,30

The treatment modality for these group of patients is emergency laparotomy and splenectomy.^3,4 The concept of splenorraphy is not indicated except for minor grades of splenic trauma especially from blunt

abdominal injuries, the aim being to avoid overwhelming post splenectomy infections (OPSI) in children less than 5 years.^7,18,30

C) Pancreas:

The pancreas is about 12.5cm long and an organ surrounded by other organs like duodenum, stomach and spleen. Thus, it is relatively cushioned from trivial abdominal injuries in some blunt trauma. Majority of pancreatic injuries, therefore, result from penetrating trauma to the abdomen.^6,18

The diagnosis of this injury is difficult. A high index of suspicion is required for identifying it. When there are associated injuries to stomach, spleen, liver, duodenum, extra-hepatic biliary system and related great vessels (venacava, portal vein, superior mesenteric vessels), its diagnosis and management become more difficult.⁴ An abdominal helical spiral CT-scan will detect most types of injury to the pancreas. This is usually done in a stable patient with lesser degree of pancreatic injury and where its diagnosis is equivocal.^3,30,71 Pancreatic injury types can be classified as follows: ²

Type I - Contusion without pancreatic capsular disruption Type II - Severe contusion with pancreatic capsular or

parenchymal rupture but with intact main duct (Wirsung).

Type III - Severe parenchymal damage with disruption of the main duct.

Type IV - Combined pancreatic and duodenal injury.^2,6

The management of this injury depends on the severity and associated injuries to other organs including the duodenum. At laparotomy any haematoma around the pancreas or lateral border of the duodenum,

requires full mobilization of the duodenum and pancreas. Also, assessment of pancreatic duct integrity is mandatory if trauma to it is noted. On the other hand, on-table pancreaticography is the most suitable method.

The main operative principles for pancreatic trauma will include:

complete haemostasis, removal of devitalised tissue and drainage of pancreatic juice.^6,18 The definitive treatment option for these injuries is dependent on types of pancreatic injuries encountered.

For Type I pancreatic injury where distal pancreatic injury and contusion do occur, drainage of the lesser sac is the required treatment using Sump or closed suction drain.^3,6

For Type II injury, suturing of the tear and drainage in advised.

In type III injury, the main duct is disrupted, as well as injuries to head and tail of pancreas, distal pancreatic resection or Roux-en-Y anastomosis to distal or proximal ends is done.

In type IV injury, debridement of the pancreas, closure of duodenal wounds and pyloric exclusion by gastrojejunostomy is performed.^22,30 Nonetheless, the more extensive type IV injury may be treated by pancreatico-duodenectomy. ^2,3

The indications for this resection or procedure are:

(a) Proximal pancreatic duct injury

(b) Injuries of the head of the pancreas involving the ampulla or the distal bile duct that exclude reconstruction.

(c) Combined devascularizing injuries to the pancreas and the duodenum.^3,30

The outcomes of pancreatic injuries vary. The pancreatic injuries are associated with high mortality from peritonitis and septicaemia.¹⁸ A major injury to the head of pancreas carries 30 – 60% risk of fistula formation.⁴

The post-operative management is often tedious and may be complicated with intra-abdominal sepsis, pancreatic and duodenal fistulae from anastomotic leakage. Nutritional support is important and a feeding jejunostomy inserted at the first operation will help to maintain nutrition.^2,22

D) Diaphragm:

Diaphragmatic injury occurs in 4–5% of patients with penetrating abdominal injuries. Both right and left sides of the diaphragm may be affected but the left side is usually more injured in blunt trauma.^1,18 This is because the liver protects the right hemi-diaphragm. The injury to diaphragm is often masked by associated injuries to other intra-peritoneal viscus like stomach, spleen or splenic flexure of the transverse colon and various segments of intestines. Sometimes, it may be overlooked during laparotomy.^6,18 In thoraco-abdominal injuries, the diaphragm is frequently injured.^3,72 If the defect is large or neglected a diaphragmatic hernia may occur as a late complication. Lacerations or defects of the diaphragm should be repaired at initial laparotomy with interrupted non-absorbable, mattress suture (prolene 2/0). Larger lacerations of the diaphragm should be repaired or bridged with a prosthetic mesh. After the repair, abdominal drainage may be unnecessary but tube thoracostomy of the affected side is of benefit to drain intra-thoracic fluid or blood for re-expansion of the lung.^3,72,73 In chronic diaphragmatic herniation of viscera, there is resultant adhesion to the lung in most cases.^1,4 The repair of the diaphragmatic defect should be done through thoracic route. The outcome of the injury varies and usually there is no long term sequelae if managed promptly.^3,22 e) Kidneys:

Open or penetrating injuries to kidneys do occur. These are less common unlike blunt trauma in peace time.⁶ The injuries may be mild, moderate or severe.

Mild or negligible injuries of kidneys is associated with mild tenderness and transient haematuria and renal swelling⁶.

Moderate trauma does present with much renal tenderness and haematuria or renal enlargement.

Severe renal injury is characterized by shock and moderate or large renal swelling. Anuria may also be a feature of the injuries^6,22.

Pathological types of renal injuries.

These includes: ^6,22.

a) Contusion or bruising of renal parenchyma b) Small subcapsular haemorrhage

c) Large subcapsular haemorrhage

d) Cortical laceration and perinephric haematuria e) Medullary laceration and bleeding into renal pelvis f) Complete rupture

g) Avulsion from renal pedicle

h) Thrombosis of renal artery or rupture of pelvis.

Clinical evidence of these injuries do occur as pain, haematuria and renal swelling. Nausea, vomiting and abdominal distension due to paralytic ileus may occur in retroperitoneal bleeding. Oliguria associated with hypotension is also noticed. Features of injury to other organs such as urinary bladder, urethra and other abdominal viscera may be present.

Complications such as perirenal haemorrhage and shock are noted in patients with these injuries. Also perirenal infection and abscess may be

present. Late complications such as hydronephrosis, renal atrophy, renovascular hypertension and renal artery thrombosis do occur⁶.

Management

These patients are resuscitated for shock by intravenons fluids, blood transfusion and analgesics. Blood pressure and pulse chart is maintained.

Serial urine collection is performed to assess the progress of the bleeding. ⁶ Investigations done will include blood for haemoglobin concentration, urea and creatinine, grouping and crosmatching of blood. Intravenous pyelogram is required to assess the extent of injury and the presence of contralateral kidney. ^6,18

About 80% percent of patients respond to conservative measures.

Surgical exploration is carried out in 10% to 20% of cases. ⁶

Surgical intervention is indicated in patients with shock, progressive blood loss and large perinephric haematoma. The procedure usually performed are debridement, drainage of perinephric haematoma, suture of renal laceration, partial nephrectomy or nephrectomy. ^6,18,22 Perinephric infection requires drainage. Late complications may require nephrectomy or repair of secondary ureteral obstruction. ^6,22

The prognosis depends on the type of injury. Renal contusion has excellent prognosis among other types of injuries.

Severe renal injuries if not treated early may lead to mortality in two to three percent of the cases. ⁶

f) Ureters

Ureteric injuries account for about 3% of all genito-urinary trauma. ⁶ The penetrating abdominal injuries affecting the ureters are uncommon.

They may result from stab and low or high velocity missiles. ²

High velocity injuries can cause delayed urinary fistulae after 7-10 days due to ischaemia of the ureter from shearing forces and cavitations along the path of the bullet. ⁶

Haematuria in ureteral injury is not often noticed. The diagnosis of the injury pre-operatively is based on the location of the entrance site of penetrating object. Non-diagnosed ureteral injuries may led to complications such as fistulas, urinomas. ²² and abscess formation. ²²

In majority of cases, intravenous pyelography will confirm the diagnosis. ^6,22 Abdominal ultrasonography can detect calyceal dilation and hydronephrosis. ² Retrograde uretero-pyelogram may reveal extravasation of contrast medium at the site of the injury.Computerized tomography scan is useful for diagnosing difficult cases.^2,6 In haemodynamically unstable patients the diagnosis is made at the time of laparotomy by intravenous injection of 5mls of methylene blue or indigo carmine dye. Extravasation of the dye stained urine confirms the presence of ureteral injury. ⁶

The principles of ureteral repair are adequate debridement, tension-free repair, spatulated end to end anastomosis, watertight closure, ureteral stenting and drainage. ²²

Surgical options for ureteric injuries include uretero-ureterostomy for injuries located in the upper and middle thirds of the ureter. The use of a double J stent is indicated after the procedure because it seems to decrease the incidence of post operative fistulas. ^2,6

More distal injuries may require ureteral re-implantation in the bladder or ureteroneocystostomy with or without a Boari flap. (Bladder flap) and in some cases by a uretero-uretersotomy to contralateral ureter. ²

Percutanous nephrosotomy is indicated to divert urinary flow in cases when primary repair is not feasible, either due to overall clinical condition of

the patient in which there is loss of a long segment of the ureter. ²² Other options in the presence of extensive ureteral injuries include a transuretero-ureterostomy or kidney auto transplantation into the iliac fossa. ²²

Prognosis

Stricture may occur after ureteric reconstruction within 3-4 years therefore careful observation is required for these patients. ⁶

g) Bladder

Urinary bladder open injuries are not as frequent as blunt trauma.

They occur following stab and high or low velocity missiles. ⁶ Bladder rupture occur in 5-10% of Patients with pelvic factures. ^6,22 External injuries may cause either extraperitoneal or intraperitoneal bladder rupture. ^2,6 When the urinary bladder is full, intraperitoneal rupture of bladder occurs while in an empty bladder extraperitoneal rupture occurs. ⁶ Contusion of bladder do occur following less severe trauma. This presents as suprapubic pains with or without bruising and haematuria.

In extraperitoneal rupture of the bladder, the features are suprapubic pain and swelling due to extravasation of urine and blood in the retropubic space. Urethral bleeding and/or haematuria and failure to pass any urine starting from the time of injury are the features.

Patients with intra-peritoneal rupture have urethral bleeding, failure to pass urine after the trauma and feature of peritonitis from extravasated urine in the peritoneum. Retrograde urethrocystogram is done to diagnose the injury site.

Extravasation of contrast confirms the bladder rupture. Post void film will identify lateral or posteriolateral bladder injuries. In bladder contusion,

In document A Hemodynamic investigation of a complete arteriovenous model of the arm, arteriovenous fistula, and distal revascularization and interval ligation (Page 62-67)