title: Nitrous oxide/oxygen inhalation provides effective analgesia during the administration of tumescent local anaesthesia for endovenous laser ablation.
abstract: BACKGROUND
  Tumescent anaesthesia (TA) is an important but sometimes very painful step during endovenous thermal ablation of incompetent veins. The aim of this study was to examine whether the use of fixed 50% nitrous oxide/oxygen mixture (N2O/O2), also called equimolar mixture of oxygen and nitrous oxide, reduces pain during the application of TA.
  
  
  METHODS
  Patients undergoing endovenous laser ablation (EVLA) of incompetent saphenous veins were included. Thirty consecutive patients inhaled N2O/O2 during the application of TA. Thirty consecutive patients received TA alone (controls). Patients were asked to complete a questionnaire immediately after the intervention to assess satisfaction with the intervention and pain-levels during the different steps of the intervention (0=not at all, 10=very much). Adverse events during the treatment were monitored.
  
  
  RESULTS
  30 patients (14 men, mean age of 44 years) were included in the N2O/O2 group and 30 patients (9 men, mean age 48 years) were included in the control group. In the N2O/O2 group a significantly lower pain score was noted (mean 2.45 points, range 0-6) compared to the controls (mean 4.3 points, range 1-9, p<0.001). Overall, 64.5% of the patients were perfectly satisfied with the N2O/O2-Inhalation. Only 4 patients receiving N2O/O2 complained of adverse effects such as unpleasant loss of control (2 patients), headache (1 patient) and dizziness (1 patient).
  
  
  CONCLUSIONS
  N2O/O2 is a safe and effective method to reduce pain during the application of tumescent anaesthesia for EVLA.
authors.affiliation: 1 Clinic for Angiology, University Hospital Zurich, Switzerland.
authors.forename: Thomas Oleg
authors.initials: TO
authors.lastname: Meier
authors.affiliation: 1 Clinic for Angiology, University Hospital Zurich, Switzerland.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Jacomella
authors.affiliation: 1 Clinic for Angiology, University Hospital Zurich, Switzerland.
authors.forename: Robert Karl Josef
authors.initials: RK
authors.lastname: Clemens
authors.affiliation: 1 Clinic for Angiology, University Hospital Zurich, Switzerland.
authors.forename: Beatrice
authors.initials: B
authors.lastname: Amann-Vesti
mesh_terms: D000280:Administration, Inhalation; D000328:Adult; D000368:Aged; D018712:Analgesics, Non-Narcotic / Q000008:administration & dosage* / Q000009:adverse effects; D000772:Anesthesia, Local / Q000009:adverse effects / Q000379:methods*; D005260:Female; D006801:Humans; D053685:Laser Therapy / Q000009:adverse effects / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009609:Nitrous Oxide / Q000008:administration & dosage* / Q000009:adverse effects; D010146:Pain / Q000209:etiology / Q000517:prevention & control*; D010147:Pain Measurement; D017060:Patient Satisfaction; D012501:Saphenous Vein / Q000601:surgery*; D011795:Surveys and Questionnaires; D016896:Treatment Outcome; D014648:Varicose Veins / Q000175:diagnosis / Q000601:surgery*; D055815:Young Adult
chemical_list: D018712:Analgesics, Non-Narcotic; D009609:Nitrous Oxide
keywords: Nitrous; analgo-sedation; endovenous; laser ablation; local anaesthesia; oxide; tumescent; varicose; veins