5. Statistical Analysis: Demographic information, patient characteristics, assignment to experimental group, and visual analog pain scale data will be entered into a spreadsheet . Pain will be recorded per patients at 5 time points: 0, 2, 5, 7, and 10 minutes. Descriptive statistics will be presented in tables and graphs. Pain scale results will be analyzed by a two-way (2x5) repeated measures analysis of variance with interaction and post hoc multiple comparisons. The primary time pair to be tested will be the difference between treatment and placebo groups in pain reduction from 0 to 2 minutes. The planned sample size is 62, with 31 in the placebo group and 31 in the nitro group. The sample size was calculated with the aid of Dr Riffenburgh. He agrees with sample size suggested above.