Intra-operative Urodynamics: Is the Test an Accurate Representation of the Lower Urinary Tract in Children
Hannah Agard Bachtel, MD1, Rhys Irvine, MD2, Eric Massanyi, MD3, Daniel McMahon, MD3, Curtis Clark, MD3.
1Texas Children's Hospital/Baylor College of Medicine, Houston, TX, USA, 2The University of Tennessee Graduate School of Medicine, Knoxville, TN, USA, 3Pediatric & Adolescent Urology, Inc./Akron Children’s Hospital, Akron, OH, USA.
BACKGROUND: Urodynamics (UDS) are typically performed in an ambulatory care setting, but the invasiveness of the test can lead to significant patient anxiety and agitation. In children who are unable to tolerate the study while awake, intra-operative UDS may be performed in conjunction with another planned surgical procedure. However, minimal data exists on the efficacy of intra-operative UDS. The goal of this study is to compare intra-operative UDS results with UDS in the post-operative care unit (PACU) to assess the accuracy and efficacy of intra-operative UDS. Theoretically, the PACU provides a more natural intravesical environment than the operating room, since the patient is no longer under the influence of anesthesia.
METHODS: With IRB approval, pediatric patients undergoing intra-operative UDS at a single institution were recruited and prospectively and retrospectively enrolled over a 5-year time period (1/2013 - 8/2018). Urodynamics were performed in the operating room, then in the PACU after recovery from anesthesia. All urodynamic tracings were independently reviewed and interpreted by a board-certified pediatric urologist. Study labels were modified to blind the reader to the location. Electromyographic (EMG) activity during filling, bladder compliance, cystometric bladder capacity (CBC), presence of leak, leak point pressure (LPP), and pressure specific volumes (PSV) at 10, 20, 30 and 40 cm H2O were compared between studies. Uninhibited detrusor contractions (UICs) were also compared. Operative data and the associated anesthesia record were extracted from the electronic medical record. Patients who received a neuromuscular blocking agent intra-operatively were excluded from the final analysis. Data was analyzed using paired t test, chi-square and Fisher’s exact test. A p-value <0.05 was considered significant.
RESULTS: Nineteen pediatric patients underwent a total of 48 urodynamic studies available for subsequent analysis. The most common anesthetic agents administered were sevoflurane (100%), nitrous oxide (74%), propofol (58%), fentanyl (53%), morphine (47%) and midazolam (32%). Cystometric bladder capacity, presence of leak, valsalva LPP, and PSV at 10, 20, 30 and 40 cm H2O did not differ between studies performed intra-operatively or in PACU. Intra-operative urodynamic studies were more likely to have decreased EMG activity during filling (p=0.02), normal compliance (p<.001), and a lower detrusor LPP (p=0.028) compared to UDS performed after recovery from anesthesia. Uninhibited detrusor contractions were less frequently observed intra-operatively (p<.001) and were lower in magnitude than those observed in the PACU. Twelve of the 19 (63%) children had UICs that were present only on the UDS in PACU and not intra-operatively.
CONCLUSIONS: There is no difference in observed bladder capacity, PSV and urinary leakage on intra-operative UDS evaluation. However, bladder compliance, detrusor LPP, and the presence and magnitude of UICs is significantly different when UDS is performed under anesthesia. For this reason, we conclude that intra-operative UDS be interpreted with caution. It is preferable to utilize ambulatory urodynamic evaluation when available to guide patient management and treatment.
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