Lidocaine Gel vs Plain Lubricating Gel for Cystoscopy

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Lidocaine Gel vs Plain Lubricating Gel for Cystoscopy

Discussion


The purpose of this study was to determine whether intraurethral lubricating gel containing 2% lidocaine resulted in lower average pain scores compared with the plain lubricating gel in men undergoing flexible cystoscopy. We found that men randomized to receive the lidocaine gel on average reported lower pain scores than men randomized to receive the plain lubricating gel. This treatment effect did not seem to vary in magnitude according to age.

For comparison with our findings, main results from the previous randomized trials of the 2% lidocaine gel versus plain lubricating gel in men undergoing flexible cystoscopy are summarized in Table 5. Studies by Palit et al. (2003), Birch et al. (1994), and Choong et al. (1997) used a scale of 0 to 100 for pain assessment; while all other studies in Table 5 used a scale of 0 to 10. To simplify interpretation, all mean pain scores in Table 5 were expressed on a scale of 0 to 10 (e.g., a mean score of 35 on a scale of 0 to 100 would be reported as 3.5 on a scale of 0 to 10). Three comparisons in Table 5 (including our current study) showed lower average pain scores in the lidocaine group relative to control with very small p-values, while the other comparisons did not reveal significant differences in pain perception between the groups. The reasons for this disagreement are not clear. In particular, gel volume and the length of time from instillation to cystoscopy do not seem to explain this variation. Because the two previously reported "statistically significant" studies in Table 5 used 20 mL of the lidocaine gel applied for 10 minutes (Holmes et al., 2001) or 25 minutes (Choong et al., 1997), one could hypothesize that instillation of 20 mL of the 2% lidocaine gel for at least 10 minutes prior to cystoscopy is a reasonable if not optimal combination of volume and timing. However, McFarlane et al. (2001) and Chen et al. (2005) used 20 mL lidocaine for 15 minutes and did not find significant evidence of anesthetic effect (see Table 5). Further, in our current study, significant treatment effect was observed with only 10 mL of the lidocaine gel applied for approximately 15 minutes. Hence, it appears that at the present time, definitive recommendations regarding optimal gel volume and timing of instillation cannot be made.

Subjects' characteristics can also be examined as a source of variation in findings reported from different trials. Mean age of patients in Table 5 ranged from 58 to 73 years, depending on the study. In the two statistically significant comparisons in Table 5 reported previously, mean age of the subjects was 61 years (Choong et al., 1997) and 64 years (Holmes et al., 2001), while in our current study, the mean age was 73 years. Hence, statistically significant comparisons were not predominantly based on older or younger patients, and in fact, represented essentially the same age range as the "non-significant" comparisons. Further, we found no evidence that the treatment effect was limited to older or younger patients in our current study, and similar results were reported by Choong et al. (1997).

Pain perception during cystoscopy may potentially be influenced by previous experience of the patients with this procedure, as well as the personal skills of the physician performing the examination. Indeed, some cystoscopers may be more gentle/skilled than others, although this is difficult to quantify. Unfortunately, it is not possible to determine whether personal skills of cystoscopers differed substantially between the studies in Table 5, and if so, to what extent these differences contributed to the observed variation in the estimated treatment effects. In contrast, the proportions of men undergoing their first cystoscopic examination differed substantially between the studies in Table 5, although this factor could not account for differences in conclusions regarding the anesthetic benefit of intraurethral lidocaine. In particular, in the two previously reported statistically significant comparisons in Table 5, the majority of subjects never had a cystoscopic examination in the past (65% in Choong et al., 1997; 69% in Holmes et al., 2001). Based on this observation, one could hypothesize that the anesthetic effect of intra-urethral lidocaine is stronger in men undergoing their first cystoscopy. However, the proportions of subjects without previous cystoscopy were also high in the trial by Chen et al. (2005) (68%) and in the trial by McFarlane et al. (2001) (100%), and neither of these trials demonstrated a statistically significant reduction in pain with the 2% lidocaine gel. Further, in our current trial, where a significant effect of the 2% lidocaine gel on pain perception was observed, 98% of the subjects had cystoscopy in the past.

Given all of the above considerations, it appears that male patients who are most likely to benefit from intra-urethral anesthesia cannot be identified based on age and history of previous cystoscopic examinations. Optimal volume of the lidocaine gel and duration of instillation before cystoscopy also remains uncertain despite completion of multiple randomized trials focused on these questions. The outcomes of these trials seemed to depend considerably on factors related to particular institutional settings, although specific factors could not be identified.

At our institution, 10 mL of the 2% lidocaine gel applied approximately 15 minutes prior to cystoscopy resulted in significant anesthetic effect, although it is not clear to what extent these findings can be generalized to other institutions. Given that intraurethral anesthesia is unlikely to cause harm and may potentially reduce pain, it seems reasonable to consider it as an option, even in the absence of definitive proof of the anesthetic effect consistently reproducible across institutions. Although for many patients, cystoscopy, even when done with a plain gel, does not seem to be a very painful procedure, decreasing pain in procedures that may not be very painful is highly desirable. Further, some men experience more than minimal pain during this procedure in the absence of local anesthesia. In our current study, among men randomized to lidocaine, no one reported a pain score of 5 or above, while in the plain gel group, one in five men (20.9%) reported a pain score of 5, which is a pain perception "half-way" to the worst pain imaginable (a pain score of 10).

Study Limitations


The strengths of our current study are randomized treatment assignment, triple blinding (subjects, nurses, and urologists), and full compliance with assigned intervention. The study was limited by race (almost all Caucasian), gender (all male), age (most were over 65), and cystoscopic experience of the patients (almost all had cystoscopy in the past). This study was terminated early, which is also a limitation in the sense that accrual of additional 30 subjects would result in more precise estimates of the treatment effect. However, early termination of the trial was necessitated by ethical considerations based on a clinical observation of consistently lower pain scores in the lidocaine group relative to the plain gel group. In particular, using the threshold by Aaronson et al. (2009) of less than 3 points on a scale of 0 to 10 as a definition of "less than moderate pain," it can be noted that 69% of men randomized to the lidocaine group and only 29% of men randomized to the plain gel group experienced less than moderate pain in the current study (see Table 3). Given a difference of this magnitude, it was decided to stop accrual and perform statistical analyses of available data. Based on our current findings, we are planning to offer the 2% lidocaine gel to all men undergoing flexible cystoscopy in our clinic.

Nursing Implications


This study was initiated after a discussion among members of our clinic staff regarding the need for the lidocaine gel prior to cystoscopy. The clinic was faced with some operational issues because lidocaine is a medication, as well as the issue of cost (e.g., lidocaine gel costs almost $10 per pre-packaged syringe versus plain gel, which costs about five cents). Our institution agreed that a study comparing the effects of lidocaine gel versus plain lubrication gel was warranted before making any institutional decisions regarding their use for patients undergoing cystoscopy.

Subjects in our study were a very homogenous group. All the men were Caucasian, most were over 65 years of age, and all had at least one previous cystoscopy. It was not our intention to enroll a homogenous group, but the population undergoing cystoscopies in our clinic typically consists of patients with bladder cancer and are almost all Caucasian, older males. Every firsttime cystoscopy patient in our clinic who was approached to participate in the study declined to participate. In each case, they were unwilling to undergo cystoscopy without lidocaine. It was also difficult to recruit patients with previous cystoscopy experience because many men may find it unacceptable to undergo the procedure without lidocaine; however, we were able to recruit 50 subjects for our study who were willing to participate. Our study participants all had the procedure done previously; thus, fear of the unknown was not a factor. However, cystoscopy may still be perceived as a very uncomfortable procedure, and in turn, may elicit a great deal of patient anxiety. Nurses implement many interventions, such as reassurance and distraction techniques. While these are useful interventions, they are not always enough. Offering lidocaine gel prior to males undergoing flexible cystoscopies is an additional measure that helps decrease the pain and make the experience less uncomfortable. While pain scores for both groups with or without lidocaine were not high (not more than 5 out of 10), there was a significant reduction of pain in the lidocaine group (see Table 5).

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