-Number of shots heart; type of gun used; position of pt when shot; distance of the pt from the gun. History should be gathered from the pt, available eye-witnesses, and emergency medical service providers
Does the patient have intra or extraperitoneal bleeding that requires surgical intervention?
Does the patient have peritoneal contamination requiring washout and repair of a hollow viscus?
Penetrating injuries with any hemodynamic instability and/or signs of intraperitoneal injury are treated operatively at the outset of management
-GSWs most often injure the small bowel followed by the colon and liver
Clinical thinking
Does the patient have an adequate airway, and ability to protect it?
Is the patient breathing? Is oxygenation and ventilation adequate? A GSW in the abdomen may penetrate the diaphragm and cause a significant thoracic injury
-Does that patient have adequate blood volume and perfusion? How does the patient respond to resuscitation, does the pt take beta blockers that may mask an appropriate tachycardia?
-evaluate the pts ability to follow commands and respond appropriately. Is neurological disability a central phenomenon from shock, or is there a direct spinal cord injury?
The patient must always be adequately exposed to evaluate all injuries, don’t over look the axial, back, gluteal cleft, and perineum.
Patients with penetrating abdominal injuries are best served by antibiotic therapy prior to operative intervention. Initial therapy should be broad, with coverage of both gram-positive and gram negative organisms. Current practice guidelines advise broad spectrum antibiotics prior to incision and throughout operation
-tentanus toxoid upon admission
The care of the trauma patient does not end with intraoperative repair of injuries. The hypothermic, coagulopathic laparotomy patient is prone to numerous postoperative complications: Expect to encounter significant post op hypovolemia, often requiring massive volume resuscitation
Anticipate (life-threatening) abdominal compartment syndrome: look for a decrease in urinary output, increasing airway pressures, decreased venous return, and increasing abdominal pressures.
HISTORY
• Need to ascertain the mechanism of the injury: damage inflicted by a low-velocity handgun is far different from the cavitating blast effect exerted by high-velocity hunting projectile. • AMPLE(allergies, meds, past medical hx; last meal; events leading to presentation) • Past medical hx provided by the patient or family may provide insight to observed physiology: for example, beta blockade may mask the tachycardia of stage II shock.

Physical Exam • A GSW to the abdomen is always explored. • Pay attn to the signs of abdominal penetration and try to reconstruct the path of injury • Be skeptical of apparent injuries: two holes aligned on a patient do not necessarily indicate entrance and exit wounds. • Does the patient have abdominal pain? Is the patient tachycardic and hypotensive because of peritoneal hemorrhage? Are respirations labored b/c of a distended abdomen and limitation to diaphragmatic excursions or because of a missed pneumothorax. • Check the NG tube after insertion: bloody nasogastric effluent? • Rectal examination may reveal blood w/in the bowel lumen. • Is the foley catheter draining blood tinged urine? • Whereas all of these findings may corroborate the need for laparotomy, hemodynamic instability, distention and peritoneal signs are nearly absolute indications for operative exploration.
Initial assessment: all pts must be completely undressed (often pts with assumed isolated abdominal GSWs will have other wounds in other areas). All pts must be log-rolled to evaluate for wounds to the back.
-local wound exploration; GSWs often destroy tissue making local wound exploration less effective for visualizing the extent of the missile tract. If the entire missile tract cannot be visualized, you need radiologic studies.

Tests to consider
Blood typing and screening: assume that all patients will require operative intervention
Obtain uncrossmatched blood, if clinically indicated.
CBC, BMP, and coagulopathy parameters are generally standard, although the yield from these tests is often low
Urine HCG should be checked in women of child-bearing age
Serum amylase: may indicate injury to a hollow viscus but, like the other serum chemistries, may lag behind clinical signs of injury.
Diagnostic peritoneal lavage (DPL) may be indicated if abdominal penetration by a bullet is equivocal. -DPL is a highly sensitie test for detecting injury following abdominal GSW. Using 5000- 10,000 RBC/HPF as positive, its sensitivity is ~96% for GSWs. Drawbacks include invasiveness, time needed to analyze the DPL effluent, and its lack of specificity for organ injuries that might be managed nonoperatively

Imaging:
Plain films: Rapid AP radiographs of chest, abdomen and pelvis. Advantageous if team member places radio-opaque markers on wound sites. -often employed to define the path of the bullet -2 planes must be imaged to det if the peritoneum was penetrated
CT scanning: only in stable patient with water-soluble oral, IV, and possibly rectal contrast. CAVEAT: the surgeon must decide when it is safe to transport a pt to a CT scanner, as it may require isolation of patient from trauma team -IV and oral contrast is often used to better visualize solid and hollow viscus injuries. -rectal contrast is added for suspected colorectal injury based on missile path or clinical findings (e.g. rectal bleeding) -in pts who do not need immediate ex lap, CT is an excellent test
FAST exam: focused abdominal sonography for trauma: less helpful than in blunt trauma, but may show intraperitoneal injury. -US is invaluable in the initial eval of the unstable trauma pt b/c it can rapidly det the presence/ absence of blood in the pericardial and peritoneal spaces but cannot rule out intraabdominal injury, esp to injury to the diaphragm or hollow viscu organs, which often bleed minimally when injured: minimal intraabdominal fluid identified by US or CT w/out other findings may be a harbinger of isolated hollow viscus or diaphragmatic injury
Diagnostic laparoscopy: allows the surgeon to identify peritoneal violation and partially inspect the diaphragm but does not enable adequate visualization of the posterior portion of the diaphragm, nor does it provide an effective means for detecting subtle hollow viscu/ retroperitoneal injuries

Hemoperitoneum
Violation of the peritoneal cavity causes injury to a major blood vessel of solid organ, causing blood to collect within the abdomen. Eventually the patient exsanguinates into the peritoneum and dies from hypovolemic shock:
TP: Pt present with any mechanism of abdominal penetration. Evolution proceeds through four defined classes of shock.
|Class |Lost Blood volume |Symptoms |
|I |0-15% |Minimal tachycardia |
|II |15-30% |Tachycardia (rate>100 bpm, tachypnea, cool |
| | |clammy skin, anxiety) |
|III |30% |Tachypnea and tachycardia, decreased |
| | |systolic BP, oliguria, confusion or |
| | |agitation |
|IV |>40% |Hypotension, narrowed pulse pressure (or |
| | |immeasurable diastolic pressure), markedly |
| | |decreased urinary output, depressed mental |
| | |status or loss of consciousness, cold and |
| | |pale skin |

Dx of hemoperitoneum can be made via laparotomy, laparoscopy, or peritoneal aspirate (diagnostic peritoneal lavage DPL) when dx of hemoperitoneum is made via laparoscopy or DPL, laparotomy should follow, as hemoperitoneum indicates significant intraperitoneal injury that require definitive repair.
Tx: Hemoperitoneum requires rapid identification and control of the source of hemorrhage. Blood should be evacuated from all abdominal quadrants, and packing is used to tamponade bleeding prior to systematic search and control.

Peritoneum
Irritation and inflammation of the peritoneum caused by blood or spilled enteric contents. Peritonitis is painful to the patient and serves as a nidus for infection, sepsis, and eventual death.
TP: the parietal peritoneum is extremely sensitive, and irritation of the tissue causes excruciating, often nonfocal, sharp pain. Involuntary muscular contraction or splinting produces a tense boardlike abdomen. Free fluid and ileus produce secondary abdominal distention
Dx: confirmed by a laparotomy, which is mandatory with peritoneal signs after penetrating trauma
Tx: when the surgeon encounters peritoneal contamination the contents should be evacuated as quickly as possible. All abdominal viscera are inspected carefully for injuries. Injured segments of intestine may be controlled temporarily with hemostats or sutures prior to definitive resection and/or repair. In cases with severe blood loss, hemodynamic instability, and physiologic derangements including hypothermia and acidosis, a temporary damage control procedure is performed. Objectives of damage control are rapid control of bleeding and immediate control of spillage from bowel injury. The patient is returned to the OR later for more definitive management of injuries and/or restoration of GI continuity.
-evidence of hemodynamic instability, peritonitis, or evisceration mandates immediate ex lap after an abdominal GSW. In the past any pt with suspected peritoneal violation was taken to laparotomy, but for properly selected pts nonop approaches are gaining favor. ~1/3 of pts w/ GSWs to the anterior abdomen and 2/3 w/ GSWs t the back have no sig intra-abdominal injuries and can be safely managed nonoperatively
Retroperitoneal hematoma
Blood contained w/in or emanating from the retroperitoneum due to injury of retroperitoneal structures.
TP: retroperitoneal hematomas are found on CT or at the time of operation. Early in the course of a laparotomy, the surgeon should investigate this anatomic space. It is divided into three zones: zone 1 = great vessels and is flanked on the left and right by zone II which extends out to the kidneys. Zone III defines the pelvic retroperitoneum.

-pts w/ a GSW to the flank and back are difficult to eval due to the potential injury to retroperitoneal structures, which DPL, US, or DL are not able to provide definitive info regarding injury to these structures.

-thoracoabdominal injuries: wounds of the upper abdomen and lower chest are esp difficult to eval due to the potential for ricochet off ribs and movement of the diaphragm.

Tx: like all vascular injuries, the first step in treating these injuries is adequate exposure, with proximal and distal control. Care must be taken when exploring the zones so as not to injure other retroperitoneal structures such as the pancreas and the ureters. In some cases, angiographic embolization can be employed to control hemorrhage. In penetrating trauma, virtually all retroperitoneal hematomas are explored; in blunt trauma, exploration is mandatory only for zone I.

GSW carry a higher morality due to their greater force and more extensive injury and cavitation created by the missile tract

Treatment of penetrating abdominal injuries:

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-typically, any pt with a high velocity abdominal GSW should be observed for 12-24 hrs before discharge. Usually, these pts are admitted and undergo serial abdominal exams even if all initial studies are negative

Anatomy:

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