Algorithm assesses need for PVR, although further study required
Meekins AR, Siddiqui N, Amundsen CL, et al. Improving postoperative efficiency: an algorithm for expedited void trials after urogynecologic surgery. South Med J. 2017;110:785-790.
To determine ways to further maximize postoperative efficiency, Meekins and colleagues sought to determine whether certain voided volumes during backfill-assisted void trials could obviate the need for PVR assessment.
Void trial results calculated to develop algorithm
The study was a secondary analysis of a previously conducted RCT that assessed antibiotics for the prevention of UTI after urogynecologic surgery. Void trials from the parent RCT were performed via the backfill-assisted method in which the bladder was backfilled in the PACU with 300 mL of normal saline or until the patient reported urgency to void, after which the catheter was removed and the patient was prompted to void immediately.
Postvoid residual levels were assessed via ultrasonography or catheterization. A void trial was considered to be passed when a PVR was less than 100 mL or less than 50% of the total bladder volume, with a minimum voided volume of 200 mL.
In the follow-up study, the authors analyzed the void trial results of 255 women of the original 264 in the parent RCT. A total of 69% of patients passed their void trial. The authors assessed the optimal positive predictive value (PPV) and negative predictive value (NPV) combinations, which were then used to create lower and upper voided volume thresholds that would best predict a failed or passed trial, thus obviating PVR measurement.
Results. When patients voided less than 100 mL, the NPV was 96.7% (meaning that they had a 96.7% chance of failing the void trial). When patients voided 200 mL or more, the PPV was 97% (meaning that they had a 97% chance of passing the void trial). Receiver operating characteristic analysis confirmed that voided volume alone was an excellent predictor of final void trial results, with area under the curve of 0.97. The authors estimated that applying this algorithm to their study population would have eliminated the need for assessing PVR in 85% of patients. Ultimately, they proposed the algorithm shown in TABLE 1.
A potential alternative for assessing PVR
This study's strengths include the use of prospectively and systematically collected void trial data in a large patient population undergoing various urogynecologic procedures. By contrast, the generalizability of the results is limited regarding other void trial methods, such as spontaneous filling and void, as well as populations outside of the studied institution.
With the algorithm, the authors estimated that the majority of postoperative patients would no longer require a PVR assessment in the PACU. This could have beneficial downstream implications, including decreasing the nursing workload, reducing total time in the PACU, and minimizing patient discomfort with PVR assessment.
While further studies are needed to validate the proposed algorithm in larger populations, this study provides evidence of an efficient alternative to the traditional approach to PVR assessment in the PACU.
WHAT THIS EVIDENCE MEANS FOR PRACTICE
Application of the algorithm proposed by the study investigators has the potential to eliminate the need for a PVR assessment in most patients following a backfill-assisted void trial.
Application of the algorithm proposed by the study investigators has the potential to eliminate the need for a PVR assessment in most patients following a backfill-assisted void trial.
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