Large Volume Paracentesis

To effectively prime the learner for the simulation they should watch this procedural video, review the clinical checklist and take the pre-quiz the day before the simulation.

Ideally, the simulation training closely precedes (days to weeks) the clinical procedure, to best reinforce their learning.  We recommend scheduling the simulations to be timed with the rotation where the learner is most likely to encounter the relevant procedure.

Both the learner and the instructor should perform the simulation with systematic and deliberate practice.  Treat the simulation as if it were a real-life procedure with sterile technique.  Simulation-Based Mastery-Learning (SBML), whereby the learner doesn't graduate the simulation training until they have met a minimum passing score (MPS), is a well-studied tool to ensure deliberate practice and effective feedback.²

Below is a Competency Assessment Tool (CAT) used for both paracentesis SBML simulation training and to assess competency for unsupervised practice in the clinical setting. 

The CAT includes three components:

1. Error-counting checklist –

• mirrors the clinical checklist
• more specifically defines each potential error in an attempt to accurately capture mistakes.
•  cutoffs for mistakes allowed in the MPS (<30/41) and UPS (<8/41) were established through an Angoff standard-setting process amongst 25 procedural experts.

2. Global Skills Assessment (GSA) – ranging from novice to expert.

3. Entrustment Score (ES) – ranging from ‘critical deficiencies' (not ready to perform on live patients) to ‘educator' (ready to serve as an instructor and back-up for complex situations).

We recommend making the checklist accessible to the learner and going through the following steps in a 60-90 minute simulation, depending on the trainee's experience with the procedure.

1. The instructor and trainee discuss the non-technical steps: indications, contraindications, consent process, & optimization of position and environment.
2. The instructor reviews the components of the procedural kit with the learner and demonstrates the proper technique for each step listed under “procedural steps” in the clinical checklist.
3. The trainee then familiarizes themselves with the kit components and practices the procedural steps.
4. The trainee signals when they are ready to do a full simulation with an assessment.  The assessment checklist is designed for the clinical setting and will have its limitations in a simulated environment.  Each simulation set will vary in which steps can be physically demonstrated.  In such cases, the instructor should simply elicit a verbal explanation of the intended step or thought process. 
   1. Reassemble the kit and simulator for a complete simulation.
   2. With the checklist out of the learners view, quiz their knowledge on the non-technical steps, then place the clinical checklist back in clear view.
   3. Perform each subsequent step from “Pre-procedural US” through “Procedural Steps”, then quiz the trainee on post-procedural steps.
   4. Throughout the simulation, the instructor marks mistakes made or instances when prompting was needed to avoid a mistake.  At the end of the simulation, the instructor determines a global skills score and enstrustment score (see page 2 of the assessment checklist below)
   5. The trainee repeats the simulation until they have accomplished a MPS:
      • Mistakes < 30, Global > 2 and Enstrustment > 2

Provide support and guidance to the trainee while also taking notice of mistakes being made and when a prompt was needed to avoid mistakes. 

Complete the checklist assessment either during or right after the procedure, depending on whether you are also wearing sterile protective equipment.

Pre-brief– remove checklist from view

1. Assess learner experience – For learners who have not yet successfully completed a paracentesis, the supervisor should plan to wear sterile protective equipment.

2. Confirm indication(s) and contraindications –This is often assumed by the time the decision to perform the procedure has been made, but in practice many trainees lack this knowledge.

3. Confirm consent has been obtained via the patient or surrogate –  If consent is unable to be obtained, confirm the emergent indication for the procedure.

Setting-up– place checklist in clear view to reinforce learning through repetition and reduce procedural errors.⁷

1. Optimize patient positioning– to create the largest gravity dependent space in the peritoneum while maintaining patient comfort.

• • • Bowel is filed with air and surrounded by fat.  It will float in an anti-gravity direction. 
    • Place the HOB to 15-45deg and rotating the patient ~15deg ipsilateral to the side of the procedure to create the largest collection of fluid in a lower quadrant. 
    • This is often not necessary to identify a ‘safe' pocket for a paracentesis, but as the ascites is evacuated the available space will decrease and the catheter will occlude sooner if the patient is not optimally positioned.

 

2. Perform a pre-procedure ultrasound–

• • • Using a low-frequency curvilinear or phased array transducer, start scanning in the RLQ/LLQ approx. 2cm superior and 2cm anterior to the superior anterior iliac crest.  This avoids the flank region musculature and the inferior epigastric vessels, which are lateral to the abdominus rectus muscles.
      • Identify an area of hypoechoic (black) fluid >2-3cm from peritoneum to visceral organ in all three dimensions.  This provides a ‘safe' pocket for a diagnostic or therapeutic paracentesis.  However, unless the maximal depth of fluid is >5cm in three dimensions, a therapeutic paracentesis is unlikely justified as this is not enough fluid to cause symptoms of increased abdominal pressure.
      • Remember the angle of the ultrasound probe as compared to the skin, as this will guide the angle of needle insertion.
      •  
    • Using a high frequency linear transducer with color or power doppler flow:
      • Assess for superficial veins at the identified insertion site.
      • Apply minimal pressure as these vessels are easy to compress.
        • • Fan the transducer so the direction of US runs slightly tangential to the direction of blood flow and slowly rotate to 90deg.  Even a thorough evaluation may fail to identify small abdominal wall veins. 
          • To complete the vascular assessment position the transducer in the axial plane and slowly slide medially until the abdominus rectus comes into view and the inferior epigastric vessels are identified.

3. Gather all supplies

4. Perform a timeout with the patient's nurse before opening any sterile supplies. Include the patient in the time-out if possible.

5. Prepare sterile gear

• • Don mask, eye protection, and sterile gloves (cap and gown are optional).
  • Prep site with 2 chlorhexidine scrubs x 30 seconds.  This differs from the method used with iodine-based solutions (“apply and let dry”).  Sterilize an area larger than the aperture of the drape.

 

6. Prepare supplies

• • Draw up lidocaine using the largest needle or filtered catheter provided.  The smaller bore needles are reserved for anesthetizing the track.
  • Identify the simple IV tubing (no one-way valves) used for draining ascites and remove any packaging

 

1. If unable to aspirate fluid initially after having advanced the catheter into the peritoneum, check that the catheter has not kinked.
2. If withdrawal of ascites slows or stops:
   1. Turn off negative pressure and move peritoneum by elevating the head of the bed, turning the patient on their side
   2. Flush the catheter port with 5-10cc sterile saline as bowel may be blocking catheter
   3. Rotate the catheter
   4. Turn off negative pressure and withdraw catheter to depth of 2cm + the distance of the skin to the peritoneum (usually total of ~ 4cm)
3. If there is too little ascites (<2cm), consider dynamic ultrasound guidance or referral to IR