Fever and Abdominal Pain - Interventional Therapy
Surgical Management of Diffuse Peritonitis (Set Margins at File -> Page SetUp at 0.0" for best result)
Procedures used for management of intraabdominal infections have at least five possible components: (A) drainage of any fluid collections, (B) closure of perforations of the GI tract by resection or diversion, (C) debridement of devitalized tissue, (D) drain placement, and (E) surgical wound management. Each of these elements is the subject of some debate.
Under certain circumstances, the procedure performed may not be optimal for control of infection. This may occur because of anatomic conditions do not allow the procedure of choice to be performed (e.g. extensive adhesions or tumor infiltration preventing mobilization of the bowel for resection or ostomy creation), unrecognized disease elements (e.g. multiple abscesses), misdiagnosis, or technical error such as inadvertent and unrecognized bowel perforation. Inadequate procedures may therefore be significant determinants of outcome that may make clinical cure less likely even with aggressive supportive and appropriate anti-infective therapy. These patients are a critical subgroup because they may in fact disproportionately benefit from highly effective antibiotic and anti-sepsis therapy.
A complex mix of factors affect a decision to perform a specific procedure, including variables such as the underlying condition of the patient, the acute physiologic response to infection, the duration of infection prior to diagnosis and treatment, the anatomic extent of disease, patient anatomy, and the availability of both post-operative intensive care support and radiographic reassessment. The complexity of this decision-making process makes the development of an algorithm quite difficult.
Operative management of secondary peritonitis involves immediate evacuation of all purulent collections, with particular attention to subphrenic, subhepatic, interloop, and pelvic collections. It is well established that the perforated bowel should be resected. This notion has evolved from studies over several decades of mortality following surgical treatment of perforated diverticulitis. Resection with end-colostomy was shown to decrease mortality significantly as compared to transverse loop colostomy and drainage. Despite recent reports of low rates of anastomotic dehiscence with primary anastomosis, surgeons have not universally accepted this concept because previously reported complication rates from primary anastomosis are staggering.
Controversies in the operative management of secondary peritonitis primarily surround wound closure techniques and scheduled re-laparotomy. Abdominal wall edema typically develops in patients with diffuse peritonitis secondary to colonic perforation or anastomotic dehiscence as part of a generalized syndrome of increased capillary permeability. This syndrome is worsened by the accepted need to provide aggressive restoration and in many cases supranormal expansion of intravascular volume. Primary closure of the abdominal incision in such patients may be difficult or even unwise. Increased intraabdominal pressure can result in compression of mesenteric and renal veins, leading in some instances to acute renal failure or bowel necrosis. This clinical entity is commonly referred to as abdominal compartment syndrome. To avoid this early postoperative complication, insertion of fascial prostheses can be performed. A variety of materials have been used, including Marlex, Silastic, polytetrafluoroethylene, or more recently an opened 3-L sterile intravenous bag. Each approach has its own virtues and problems.
Impermeable materials can exacerbate peritonitis and should be used only if planned re-laparotomy is to be undertaken. However, multiple laparotomies for abdominal sepsis have been correlated with increased mortality and poor outcomes, especially because of increased incidence of fistula formation. Reoperation to control intra-abdominal pathology has also been shown to cause substantial hypotension in the perioperative period due to increased cytokine release; demonstrating an inverse correlation between serum interleukin-6 levels and postoperative mean arterial pressure.
The mesh materials, particularly in patients with diffuse peritonitis, effectively create an open abdominal wound that allows continual abdominal drainage. However, these patients require extensive wound care. An alternative to definitive closure of the abdominal wall incision includes temporary abdominal closure using the clear Bogota bag. This clear 3-L saline intravenous solution bag is drained and opened to offer a one-ply impermeable dressing. This bag is sutured at the seam to the fascial edges to prevent contraction and provide a non-adherent surface to prevent development of adhesion. Additionally, with a clear bag on each side of the fascia, the edges can be closed together to provide a semi-sterile environment for the abdominal wound.
The advantages of such a temporary closure are two-fold. One, the fascia edges remain fresh, avoiding the injury encountered with re-laparotomy. Two, the bag can be cinched periodically to preclude fascial retraction, which may lead to difficult hernia closure in the future. This method has been used with success at the University of Cincinnati, often allowing for beside washout of intra-abdominal fluid collection and frequent re-assessment of the peritoneal cavity, while preserving and extending the viability of the abdominal fascia.
These techniques are often used when the patient is so hemodynamically unstable that bowel anastamoses are not performed (if resections have been done). Because of concerns for absence of sufficient mesenteric blood flow to allow for anastamotic healing, bowel ends may be left stapled. Anastamoses are then performed when shock has been reversed.
Percutaneous Abscess Drainage (PAD)
Percutaneous abscess drainage (PAD) and operative intervention are best viewed as complementary rather than competitive techniques. When feasible, non-operative (i.e., percutaneous) drainage of abscesses is preferable to open surgical intervention due to the initial patient condition decline that nearly universally accompanies operative manipulation of intra-abdominal infection. The exact basis for this is unclear, but a substantial proportion of patients undergoing emergency operation for intra-abdominal infection experience acute hemodynamic compromise in the early post-operative period. When used for appropriate indications, PAD is at least as effective as operation and is associated with less morbidity.
Inflammation may manifest as a phlegmon (viable inflamed tissue), a liquefied abscess, infected necrotic (nonviable) tissue, or a combination of all. Liquefied abscesses are drainable, whereas phlegma and necrotic tissue are not. Decisions regarding which modality to utilize are largely based on CT findings and require experience, clinical judgment, and careful consideration of underlying and coexistent disease processes. Close cooperation between the surgeon, interventional radiologist and other physicians involved in the patientís care is mandatory. Specific indications for PAD have expanded significantly and now include many conditions that were previously thought undrainable, such as multiple or multiloculated abscesses, abscesses with enteric communication and infected hematomas.
It is important to define the goals of the procedure in evaluating indications and success. Potential outcomes include cure, temporization, palliation and failure. A cure is achieved when the abscess is resolved by the drainage procedure. Temporization allows resolution of an abscess and clinical improvement, with operative intervention needed to treat the underlying cause or resect necrotic tissue. The benefits of temporizing relate to the improved physiologic condition of the patient and the reduction in the extent of infection as initial healing occurs. Palliation is achieved with improvement in the patientís condition due to abscess drainage, despite the presence of a fatal underlying condition. We consider temporizing and palliative results to represent success.
The basic requirements for PAD include a safe route of percutaneous access and the presence of a fluid collection of drainable consistency. Bleeding dyscrasias are a relative contraindication, similar for any interventional procedure. Safe percutaneous access is attainable in most cases. It is generally possible to distinguish drainable fluid from phlegmon or necrotic tissue using a combination of imaging and fine-needle aspiration. Not all fluid collections require drainage, although it is generally required for those that are infected and for sterile collections that cause symptoms due to mass effect. This determination must be made on an individual basis.
Technical Aspects of PAD
It is important that the drainage route not cross a sterile fluid collection or other infected space because of the risk of cross-contamination. Crossing the pleural space for thoracic and upper abdominal drainage carries the risk of empyema formation. It is acceptable to cross the peritoneal space to drain an extraperitoneal abscess. Placement of a catheter through the small bowel or colon should always be avoided. Transgastric drainage of lesser sac pseudocysts has been advocated by some authors and appears to be safe, although this approach remains controversial. Lesser sac collections also can be approached trans-hepatically through the left lobe of the liver, although traversing solid organs should be avoided whenever possible. Obviously, it is important to be aware of, and avoid, major vascular structures.
After catheter placement, the cavity should be evacuated as completely as possible and irrigated with saline until the fluid is clear. Initial manipulation of the catheter(s) and irrigation should be done as gently as possible to minimize the induction of transient bacteremia and subsequent potential hemodynamic instability. Immediate imaging determines the need for repositioning of the catheter, placing a larger-bore catheter or placing additional drains. For cavities that are completely evacuated at the initial drainage and for which there are no abnormal communications to viscera, simple gravity drainage generally suffices. For larger or more viscous collections and those with ongoing output due to fistulous connections, suction drainage with sump catheters is more effective. Thoracic drains always should be placed to water-seal suction to avoid the complication of simple or tension pneumothorax.
Proper catheter management following the initial placement is a critical determinant of success and requires the interventional radiologist to become an active member of the management team. Drains should be checked regularly (at least daily) to monitor the volume and nature of the output, ensure adequate function and clinical response, and quickly recognize and correct any catheter-related problems. Most authorities recommend periodic irrigation of the drains, once or several times per day, with sterile saline. This can be performed by either physicians or trained nurses. In general, irrigation with proteolytic agents or antibiotics is of no value, although fibrinolytic agents may be useful for evacuation of fibrinous or hemorrhagic collections.
No standard protocol has been established for follow-up imaging. Repeat imaging studies and catheter injections are frequently used to document progress and identify problems. It is occasionally necessary to replace or reposition drains or add additional catheters. The need for follow-up imaging studies should be determined on a case-by-case basis by monitoring clinical progress and drainage output.
Catheters should be removed when criteria for abscess resolution are met. Clinical criteria of success include resolution of symptoms and indicators of infection (fever and leukocytosis). Catheter-related criteria include a decrease in daily drainage to less than 10 mL and a change in the character of the drainage from purulent to serous. Radiographic criteria include documentation of abscess resolution and closure of any fistulous communications. If catheters are maintained until these criteria are satisfied, the likelihood of recurrence of the abscess is minimized. Although some authorities recommend gradual catheter removal over several days, we usually remove the drain in one step and have had no significant problem with recurrence. For sterile fluid collections, the drain should be removed as soon as possible, generally within 24 to 48 hours, to minimize the risk of superinfection.
Causes of PAD Failure
In evaluating the causes of PAD failure, a number of factors are consistently identified. Among these factors is fluid that is too viscous for drainage or the presence of phlegma or necrotic debris. Technical modifications such as increasing the drain size and irrigation can salvage some of these drainage procedures. Recognition of phlegmon or necrotic tissue on follow-up imaging studies may lead to cessation of attempts at PAD or a modification of the expected goal. Multi-loculated collections and multiple abscesses are another cause of failure that can be minimized by using an adequate number of catheters along with mechanical disruption of adhesions with a guidewire. Fistulous communications, either unrecognized or persistent, are yet another potential cause of failure, as is drainage of a necrotic tumor mistaken by imaging to represent an abscess. Recognition of a significant soft tissue component, maintenance of a high index of suspicion and the use of percutaneous biopsies can minimize the risk of failing to appreciate the presence of tumor. Suspicious fluid also can be sent for cytologic assessment. The success rate for PAD tends to be lower in immunocompromised patients.
Low pelvic abscesses in contact with the rectum or vagina can be treated surgically by incision and drainage through these organs. The same approach can be taken using sonographic guidance, and advances in endoluminal ultrasound techniques have facilitated such procedures. Experience with ultrasound-guided transrectal and transvaginal drainage is growing, and these procedures appear to be effective and well tolerated. Good success also has been achieved in the management of tubo-ovarian abscesses complicating pelvic inflammatory disease that are refractory to medical management. In most cases, the need for hysterectomy and oophorectomy due to pelvic abscess has been outdated.