Self-Administered Nitrous Oxide (SANO) During Transrectal Prostate Biopsy to Reduce Patient Anxiety and Pain: A Double-Blinded Prospective Randomized Controlled Trial
Suprita Krishna, MD, Abigail Escobar, BS, Alejandro Abello, MD, Chris Mistretta, BS, Boris Gershman, MD, Peter Chang, MD, Andrew Wagner, MD, Ruslan Korets, MD, Kristen Schreiber, MD, Aria Olumi, MD, Heidi Rayala, MD, Heidi Rayala, MD.
Beth Israel Deaconess Medical Center, Boston, MA, USA.
BACKGROUND: More commonly used outside of the US, nitrous oxide is gaining traction in the ambulatory setting as a method to decrease peri-procedural anxiety and pain. When used as a single agent at concentrations <50%, nitrous oxide is classified as minimal sedation, and does not require the presence of anesthesia personnel, NPO status, an escort home. The effects of nitrous have near-immediate onset and rapid offset (3-5 minutes), thus providing a promising option for many urologic outpatient procedures including outpatient prostate biopsies, which in this era of active surveillance for prostate cancer are significantly increasing in frequency. Although lidocaine block provides sufficient analgesia, it does not directly address the anxiety provoked by prostate biopsies. Our ongoing study seeks to determine whether self-administered nitrous oxide (SANO) decreases anxiety and pain perception in patients undergoing transrectal prostate biopsy. METHODS: This is an interim analysis of an ongoing single-center prospective randomized double-blind controlled trial comparing SANO versus oxygen placebo in patients undergoing transrectal prostate needle biopsy. Baseline and post-procedure pain levels were evaluated using the Baseline Pain Index (BPI) and the Visual Analog Scale for Pain (VAS-P). Anxiety levels were measured using the Visual Analog Scale for Anxiety (VAS-A), the State-Trait Anxiety Inventory (STAI), and the Situational Pain Catastrophizing Scale (SPCS). Operator ease was measured by surveying the blinded Urologist on difficulty of transrectal probe insertion, maintenance of positioning, and perceived tolerance of the procedure by the patient. Vital signs were recorded before, during, and after the procedure, and patients were screened for peri-procedural complications that may be related to SANO. RESULTS: An interim analysis was conducted on the initial 38 patients (19 SANO, 19 oxygen placebo) enrolled in our study. Decrease in anxiety, measured by VAS-A, was significantly higher in the SANO group vs oxygen placebo (1.3 vs 0.63; p=0.04).Pain perception, as measured by VAS-P, was also lower in the SANO group, though this did not reach statistical significance (0.79 vs 1.68; p=0.1). With regards to operator ease, operating Urologists reported transrectal probe insertion was better than expected in the SANO group (53% vs 21%), with better patient maintenance of position (53% vs 16%), and improved patient tolerance of the procedure as perceived by the Urologist (53% vs 26%). Procedure time was slightly longer in the SANO group, though this did not reach statistical significance (11.1 vs 10.2 min) CONCLUSIONS:
In our interim analysis, patients receiving SANO during transrectal prostate biopsy had significantly lower anxiety and demonstrated a trend towards lower pain perception. Blinded Urologists scored superior operator parameters in the SANO group, with minimal increase in procedural time. These encouraging results support the incorporation of SANO to improve patient experience of care during prostate biopsies and may be a particularly promising option in those patients with a history of anxiety or apprehension surrounding invasive procedures.
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