US Guided Versus BlindI&D for Treatment of Soft Tissue Abscesses in the ED
Condition: Abscess
MeSH terms: Abscess
Study type: Interventional

Summary: 
      Standard treatment for a soft tissue abscess involves incision over the area of maximum
      fluctuance with drainage of purulence from the abscess cavity. The use of bedside ultrasound
      to guide this drainage has the potential to improve treatment outcomes by ensuring complete
      drainage of the cavity.

      Our hypothesis is that the use of ultrasound for guidance of incision and drainage of soft
      tissue abscesses will decrease treatment failure rate compared to standard blind incision and
      drainage.

      This hypothesis will be tested utilizing a blinded, randomized trial comparing standard
      incision and drainage to ultrasound guided incision and drainage.
    

Detailed description: 
      4) Background* The incidence of soft tissue infections is increasing, representing over 30
      million emergency department visits per year. While there has been extensive research in
      recent years surrounding the use of antibiotics for soft tissue abscesses, the surgical
      management remains unchanged with standard therapy consisting of blind incision and drainage
      of the abscess cavity.

      Despite incision and drainage and a spectrum of antibiotic coverage, treatment failure rates
      for these infections range from 5-20%. It is possible that part of this treatment failure can
      be attributed to inadequate abscess cavity evacuation. With blind drainage, it is possible
      that residual purulence or unforeseen satellite abscess cavities contribute to the
      persistence of the infection.

      Ultrasound has been shown to aid in the identification of soft tissue abscesses and to help
      differentiate cellulitis from an abscess. Over the last decade, clinician performed bedside
      ultrasound has become a standard in the practice of emergency medicine with proficiency
      requirements now in place for graduating emergency medicine residents. While many
      practitioners have in fact adopted ultrasound in its use for the identification of abscesses,
      few subsequently use the ultrasound for procedural guidance.

      We are specifically interested in studying the use of ultrasound for identifying the ideal
      location for initial incision as well as use of post procedural ultrasound to confirm
      complete evacuation of abscess purulence.

      5) Inclusion and Exclusion Criteria*

      Subjects enrolled in this study will include patients presenting to the emergency department
      with a diagnosis of soft tissue abscess. This includes patients of all ages and gender but
      will exclude individuals who cannot give consent or are prisoners (as they cannot return for
      follow up or be contacted for follow up).

      Inclusion Criteria:

        1. Soft tissue abscess suspected by patient history and physical exam and confirmed by
           bedside ultrasound

        2. Able to provide written consent/ assent

        3. Incision and drainage to be performed by ED physician

      Exclusion Criteria:

        1. Peritonsillar abscess

        2. Pilonidal cyst, genital or perirectal abscess

        3. Post-surgical wound infections

        4. Pregnant

        5. Prisoners

        6. Previous incision and drainage for current abscess

      6) Study-Wide Number of Subjects* N/A - Not a multi center study.

      7) Study-Wide Recruitment Methods* Study subjects will be recruited from the patient
      population of the emergency departments on the Memorial and University campuses of
      UMASSMemorial Medical Center. Patients with signs and symptoms of soft tissue abscess
      confirmed by bedside ultrasound will be identified and enrolled by treating physicians. This
      will occur 24 hours a day, 7 days a week.

      8) Study Timelines* A study subject's participation in the study will last for 1 week from
      the time of enrollment. This will consist of the initial study visit (emergency department
      encounter for treatment of the abscess), a follow-up visit at 2-3 days for wound evaluation
      and wick removal, and a telephone encounter at 1 week to 10 days.

      Based on previous studies conducted by our group with a similar patient population and study
      protocol, we anticipate enrollment of 274 patients will take 2 years.

      9) Study Endpoints*

      The primary endpoint is failure of treatment at 7 days. This is defined as any of the
      following:

        1. Need for repeat incision and drainage

        2. Need for additional antibiotic coverage

        3. Hospital Admission for intravenous antibiotics following the initial encounter 10)
           Procedures Involved* Patients presenting to the emergency department with suspected
           superficial abscesses that require an incision and drainage will be eligible for
           enrollment. Patients will be randomized into one of two groups: 1) Ultrasound Guided
           Incision and Drainage and 2) Standard Incision and Drainage. As a patient is identified
           for enrollment, the investigator will open a study packet containing standardized data
           collection sheet, consent documents and random designation for treatment group.

      Group 1 Protocol: Ultrasound-guided Incision and Drainage Patients will be identified that
      require Incision and Drainage. An initial ultrasound will be performed to localize the
      abscess cavity. Anesthetic will be provided in the standard fashion by injected into the skin
      around the abscess. Incision of the skin overlying the abscess cavity and drainage of the
      purulent material will be followed by a repeat ultrasound to assess for complete drainage.
      Any additional pockets identified will be targeted for drainage until repeated ultrasound
      imaging demonstrates that the abscess cavity is completely drained. This post procedural
      ultrasound is performed on all patients currently undergoing ultrasound guided drainage of a
      superficial abscess. In patients where drainage cannot be completed, surgery will be
      consulted. The procedure will then be completed with placement of an iodoform wick and bulky
      dressing. Patients will be placed on oral antibiotics at the discretion of the treating
      attending physician and instructed to return in 2-3 days to the emergency department for
      re-evaluation and wick removal or sooner if problems arise. If necessary, additional drainage
      maybe performed. Additional I&D will be performed with or without ultrasound at the
      discretion of the attending physician.

      A telephone follow-up 7-10 days post-procedure will be performed. Questions asked in follow
      up are located on the follow-up data sheet. See attachments or addendum. Blinding to the
      treatment group is accomplished by having follow up to determine the outcome of the treatment
      performed by an individual who is blinded to the initial ultrasound findings or treatment
      group.

      Group 2 Protocol: Standard Incision and Drainage Patients will be identified that require
      Incision and Drainage*. Anesthetic will be provided in the standard fashion by injection in
      the skin around the abscess. Incision of the skin overlying the abscess cavity and drainage
      of the purulent material will be followed by placement of an iodoform wick and bulky
      dressing. Patients will be placed on oral antibiotics at the discretion of the treating
      attending physician and instructed to return in 2 days to the emergency department for
      re-evaluation and wick removal or sooner if problems arise. If necessary, additional drainage
      maybe performed. Additional I&D will be performed with or without ultrasound at the
      discretion of the attending physician.

      A telephone follow-up 7 days post-procedure will be performed. This is the same follow up as
      in group 1. The research personnel will introduce themselves as research personnel from UMASS
      and will inform the subject that they are following up from their recent visit to the ED.
      They will ask the questions from the telephone follow-up data sheet and will refer to it as
      they conduct the follow up.

      Blinding to the treatment group is accomplished by having follow up to determine the outcome
      of the treatment performed by an individual who is blinded to the initial ultrasound findings
      or treatment group.

      *This decision may be made solely based on history and physical exam or by inital
      identification with ultrasound. If the presence of an abscess is initially identified without
      ultrasound, the original treating physician can continue to perform the Incision and Drainage
      procedure. If the presence of an abscess is initially identified with an ultrasound then
      another physician will need to perform the standard Incision and Drainage. The second
      physician is at liberty to perform the standard history and physical to assess the presence
      of the abscess prior to drainage. The second physician may be another resident or the
      attending physician overseeing the patient's care, provided they are blinded to the initial
      ultrasound identifying the presence of the abscess.

      A standardized data sheet will record patient information, results of the procedure, time to
      perform the procedure, need for additional drainage and post-procedure recurrence of the
      abscess, need for change in oral antibiotic coverage and need for admission to the for
      intravenous antibiotics.

      12) Data Management* Power Calcuation - Assuming an alpha of 0.05 and a beta of 0.2 and
      projected failure rate in the blind incision and drainage group of 20%, 119 subjects in each
      group will be required to detect a 20% reduction in treatment failure. Accounting for a 15%
      loss to follow-up will require a total number of subjects of 274 subjects. Patients assigned
      to each group will undergo analysis using the intention to treat principles.

      Data will be stored on a password-protected computer in the locked offices of the department
      of emergency medicine on the University Campus of UMASSMemorial Medical Center. Only study
      personnel and the UMASS IRB will have access to the data.

      Descriptive data will be analyzed using mean and standard deviation. Comparison between
      groups will be performed using Chi square analysis (categorical data) and Student's T-test
      (continuous data).
    

Intervention name(s): Ultrasound Guided Incision and Drainage; Blind Incision and Drainage
Intervention type(s): Procedure; Procedure
Intervention description(s): Ultrasound guidance of the abscess drainage; Incision and drainage of abscess guided by physical exam alone
Other intervention name(s): I&D
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: None (Open Label)
Primary purpose: Treatment