Sangre en el Abdomen y Ahora?

Learning Objectives

Discuss the etiology, general approach, diagnostic and therapy of the hemoperitoneum in small animal patients.

Etiology

Etiologies of hemoabdomen in dogs and cats can be categorized into traumatic and nontraumatic causes. Blunt or penetrating trauma can cause hemoperitoneum, with vehicle injury recognized as the leading traumatic etiology. From 40 dogs that had vehicle trauma, 38 dogs were found to have hemoabdomen diagnosed by ultrasound and fluid analysis.

Nontraumatic causes of hemoperitoneum include acquired coagulation disorders as in rat poison, other coagulation defects, rupture of ill organs an intra-abdominal neoplasm. A recent study report a moderate incidence of spontaneous hemoperitoneum cases in cats with liver diseases as lipidosis. A retrospective study of dogs with nontraumatic hemoperitoneum identified malignant neoplasia as the cause for hemoperitoneum in 24 of 30 dogs with a definitive diagnosis.

History and Clinical Signs

The physical exam can point toward a possible hemoabdomen when reveal abdominal distention, a fluid wave, a palpable abdominal mass, or abdominal pain is found. A minimum amount of 40 mL/kg of peritoneal fluid is necessary to detect a fluid wave, making abdominal distension an insensitive indicator of early free abdominal fluid accumulation. During the triage, a detailed evaluation of the perfusion parameters (BP, MM, CRT, FP, HR, Temp) will help to categorize the patient according to level of severity of presenting clinical signs (i.e., catastrophic, severe, or mild). Patients presenting with catastrophic hemorrhage will be in late decompensation and at risk for sudden death.

Severe clinical signs suggest acute or large volume bleeding and the need for immediate treatment with fluids and volume support. Any diagnostics should be delayed until the patient is stable. Patients presenting with mild clinical signs may have normal perfusion parameters with no clinical signs or just mild symptoms of compensation as short CRT, rapid HR. Those patients may have normal BAR mentation, with some or none variable abdominal findings. Those mild signs may suggest chronic or small volume hemorrhage.

The primary treatment goals are:

 Address hypovolemia

 Diagnose hemoperitoneum and identify main abnormalities

 Maintain oxygen carrying capacity

 Treat and stop any ongoing bleeding

If clinical signs indicating severe shock and hypotension is present, immediate resuscitation will precede diagnostics procedures; however a minimum data base should include total solids (TS) or plasmatic protein (PP), packed cell volume (PCV), solids (TS), and whenever possible blood pressure (BP).

Addressing Hypovolemia

Stabilization of patients experiencing hemorrhagic shock is a subject of intense research and controversy. Hypotensive resuscitation requires administering fluids to a patient with suspected ongoing bleeding to a low normal blood pressure, usually 70 mm Hg systolic. Large amount of intravenous fluids helps cardiovascular stability initially, but can have adverse effects on hemostasis in actively hemorrhaging patients. Bolusing large amounts of fluids may cause a dilutional coagulopathy that may enhance further bleeding, and can disrupt blood clot formation by increasing perfusion pressure and decreasing blood viscosity. Many experimental animal models of hemorrhagic shock have shown a reduction in the risk of death when a strategy of hypotensive resuscitation was employed.

A bolus infusion of crystalloids, should be followed by a close monitoring of the patient for cardiovascular stability. Subsequent aliquots may be administered if necessary. In patients with more significant signs of hemorrhagic shock (i.e., if hypotension is present) colloids can be administered with the crystalloids to support both blood pressure and colloid oncotic pressure, which may be low due to significant serum protein loss.

Hypertonic saline (7% solution) can also be administered as a single bolus of 2–4 mL/kg in conjunction with the colloid and isotonic crystalloid infusions for rapid volume expansion.

Analgesia/Sedation

Hemoabdomen is painful and often those patients presented after very anxious circumstances: Sedation and analgesia is an important part of the treatment and should be used rationally and wisely.

Hydromorphone 0.025–0.2 mg/kg IV, IM or SC; fentanyl 0.005–0.04 mg/kg IV, as in CRI 005–0.01 mg/kg/h, buprenorphine 0.01–0.02 mg/kg IM-SQ or through the oral mucosa in cats are valid options.

Diazepam 0.2–0.5 mg/kg IV; midazolam 0.2–0.5 mg/kg IV, IM or SQ can be used for sedative purposes.

Maintain Oxygen-Carrying Capacity

Transfusions should be considered whenever there are signs compatible with severe anemia and hemorrhagic shock (tachycardia, tachypnea, bounding pulses, collapse) and there is a declining trend in PCV and Hgb values after initial fluid resuscitation. As a general guideline transfusion is recommended when PCV reach 25% or less and the Hgb concentration is below 8 g/dL. However, in cases with severe and active hemorrhage, transfusions could be necessary before reaching those values.

Abdominal counterpressure can be quickly applied in dogs for rapid control of intra-abdominal hemorrhage regardless of etiology. This procedure can provide hemostasis, and may be the only option for hemostasis when owners reject surgical intervention. With application of abdominal counterpressure even a small reduction in the radius of a vessel is translated into a reduction in flow and it is often enough to reduce or even stop hemorrhage from vascular defects. A modification of this technique is the incorporation of the pelvic limbs into the counterpressure wrap (hindlimb and abdominal counterpressure-HLAC) to avoid the compartmentalization of blood in the pelvic limb vasculature and to avoid occluding the caudal abdominal vena cava.

Abdominal compartment syndrome is defined as abdominal hypertension with evidence of renal, pulmonary or hemodynamic compromise. Decreased glomerular filtration rate, metabolic and respiratory acidosis, and reduced ventilator function have been associated with the use of pneumatic garments in humans. In an experimental study of abdominal counterpressure application in dogs, no gross evidence of ischemic organ damage or changes in tidal volume were observed.

Diagnostic Imaging

Imaging studies should be delayed until the patient is stable enough to tolerate positioning, sedation and restraint. Radiographs are not specific for patients with hemoperitoneum been loss of serosal detail are the most common finding. When trauma is the cause for the hemoabdomen, X-rays may identify concurrent pneumoperitoneum. Please remember that abdominocentesis may lead to iatrogenic pneumoperitoneum.

Focused abdominal sonography for trauma (FAST) was developed in humans for the evaluation of blunt and penetrating abdominal trauma, and evaluation for the presence of free abdominal fluid. A FAST protocol has been described for dogs and consists of examination of four intra-abdominal regions (patient in left lateral recumbency): (1) immediately caudal to the xiphoid process, (2) on the ventral midline over the bladder, (3) over the right flank, (4) over the most gravity dependent area of the left flank In a prospective study of 100 dogs presenting for motor vehicle trauma, a FAST examination was found to have 96% sensitivity and 100% specificity for the detection of free abdominal fluid but it is not specific for hemoperitoneum. The US examination often is not able to localize the specific source of bleeding but can aid in the identification of intra-abdominal masses and evaluation of organ parenchyma. Computed tomography (CT) is the standard diagnostic and monitoring tool used in the management of hemoperitoneum in humans, but disadvantages of standard CT in veterinary medicine include the need for an anesthetic procedure, limited availability, cost, and the need for specially trained operators.

Monitoring

The goals of monitoring the dog with hemoperitoneum are to assess the progress of resuscitative efforts and to detect early evidence of ongoing or recurrent hemorrhage. Heart rate, CRT, pulse quality, and blood pressure are assessed to monitor perfusion with the trends of change often being more important than the absolute values.

Ongoing increase in the abdominal diameter may indicate ongoing hemorrhage, as established in humans. No data exist in veterinary medicine patient, and expansion of the abdominal diameter.

Indications to pursue surgical management in dogs with hemoperitoneum

 Abdominal wall or diaphragmatic hernia

 Penetrating abdominal trauma

 Pneumoperitoneum

 Septic or bile peritonitis

 Hemorrhage from abdominal mass

 Organ ischemia: GDV, splenic torsion, liver lobe torsion, mesenteric volvulus

 Continued decreasing peripheral PCV in conjunction with increasing abdominal fluid PCV on serially collected samples

 Inability to correct perfusion abnormalities with fluid and transfusion therapy

 Continued drop in blood pressure with attempts to remove abdominal counterpressure

If the patient is hemodynamically stable at the time of surgery it should be clipped and surgically prepared from the cranial thorax to the caudal abdomen. The inguinal regions are included to allow access to the femoral veins to place large bore catheters for rapid fluid infusions, if necessary.

Surgical Intervention

In the patient with large-volume and ongoing hemorrhage, the sudden decrease in abdominal pressure through the release of abdominal counterpressure or in making the abdominal incision can result in massive hemorrhage and rapid decompensation to the point of hemodynamic collapse. If abdominal counterpressure is in place and hemodynamic collapse is a possibility when the counterpressure is removed, then it is not removed until the surgeon is gowned and gloved and the instrument pack is opened. After abdominal counterpressure is removed a rapid surgical prep is performed.

The surgery team should be trained on handling complicated bleeding lesions and surgical scenarios. Detailed techniques on how to address surgically a hemoabdomen are available in pertinent literature.

References

References available upon request.