Nitrous Oxide (KALINOX®) Inhalation and Tolerance of Intravesical Botulinum Neurotoxin A Injection: a Double-blind Randomized Controlled Study

First line treatment for detrusor hyperreflexia is the use of antimuscarinic medications. However, these medications can have unwanted side effects and often are not good enough to decrease incontinence in cases of severe neurogenic detrusor overactivity. Some invasive surgical procedures are possible such as sacral nerve stimulator, sacral rhizotomy, bladder myomectomy and bladder augmentation. But there are still few treatment option for this medical complication. Recently, some data are showed the clinical application of botulinum neurotoxin A (BTX-A) into detrusor muscle in cases of resistant neurogenic detrusor overactivity to conventional treatment with anticholinergic medication. In these studies the authors perform intravesical BTX-A injections. First 300 units Botox are diluted with 30 ml of preservative-free saline. Using a rigid cystoscope and an injection needle, BTX-A is injected into 30 sites within the detrusor muscle.

To reduce the pain, instillation of lidocaine before botulinum-A toxin injections is used into the bladder. On a 10-point rating scale the mean pain score of the patients who underwent the injections of Botox after conventional lidocaine instillation is 4.0 (SD 1.6).

The used of KALINOX® (50% nitrous oxide and oxygen) inhalation has demonstrated analgesic efficacy in various procedures (obstetric, liver biopsy, transrectal ultrasound guided prostate biopsy, emergency...) associated with mild to moderate pain and it is technically simple to use. Early studies indicated that 30% nitrous oxide is equipotent to 10 to 15 mg. morphine. Except in patients with severe chronic obstructive pulmonary disease KALINOX® inhalation is a safe and acceptable method of sedation and analgesia. It is a nonirritant and is excreted unchanged from the lungs.

The aim of this study is to investigate the safety and efficacy of analgesia with N2O/O2 inhalation for detrusor BTX-A injections using a rigid cystoscope. Will be included patient with severe neurogenic detrusor overactivity but with preserved bladder sensibility treated with botulinum-A toxin injections into the detrusor muscle Patients will be randomized into a group that will receive KALINOX® via a breath activated device and a control group that receive oxygen through a similar breathing device. The investigator will be involved in the randomization process since the gas cylinders will be covered and they will be blind to the gas used. All patients involved will be blinded to the gas that they will inhale. The patients will score the injection pain and the anxiety on a 10-point rating scale. Furthermore the duration of the practice will be measured.

The hypothesis is that analgesia with KALINOX® will show a significant difference in pain perception among the 2 groups.