Nitrous Oxide for Analgesia During Office Urethral Bulking

Inclusion Criteria: * Female patients * greater than or equal to 18 years old * with demonstrable stress incontinence on supine stress test * undergoing calcium hydroxylapatite injection for urethral bulking for the first time * able to consent to the study and procedure Exclusion Criteria: * \< 18 years old * prior urethral bulking therapy * predominant urge incontinence symptoms * contraindications to nitrous oxide * pre-existing significant cardiopulmonary disease * hypotension defined as systolic blood pressure (BP) \< 90 or diastolic BP \<50 on initial BP in the office * chronic pain disorders (specifically fibromyalgia, chronic pelvic pain, sciatica or chronic low back pain, painful bladder syndrome) * chronic narcotic use (defined as taking a narcotic medication \>3 days per week during the past two weeks) * pregnancy * conditions of air trapping (bullous emphysema, bowel obstruction, pneumothorax, intracranial air, middle ear conditions, status post recent diving, recent eye surgery) * lidocaine allergy * neurologic diseases impairing pain perception.