Background/Purpose: Juvenile idiopathic arthritis (JIA) is the most common rheumatic disease of childhood affecting 1 in 1000 children. Medical management for arthritis often includes intra-articular corticosteroid injections. The inhalation of nitrous oxide (N₂O) in painful procedures is widely recognised in adults, yet is underused in children and young people (CYP). N₂O is quickly absorbed, having low solubility in water and fat, and rapidly eliminated from the body when inhalation stops. It is safe, fast-acting, and non-invasive, reducing apprehension and anxiety. The use of N₂O has increased access for CYP requiring painful procedures such as joint injections (JIs) that may have previously required a general anaesthetic. We aimed to describe a population of children receiving JIs with N₂O at our center and the wait time for JIs with N₂O once a decision to inject was made.

Methods: Data was collected retrospectively from available charts of children receiving JIs with N₂O from January 2002 to April 2012 at our centre. Demographics, number of JIs (including types of joints injected), and number of repeat JIs within a year were recorded. Time from decision point (DP) to JI was calculated for JIs performed in 2011-2012.

Results: 397 JIs with N₂O on 292 occasions (140 males, 152 females) were performed from 2002-2012. The median age at time of JI was 13.78 (range 6.38 to 18.97 years). The median number of JIs performed with N₂O per year was 24 (range 14-53). On 48 occasions JIs were performed subsequent to one done earlier that calendar year. The median number of repeat JIs per patient requiring them was 1.

From 2011-2012, 79 JIs were performed with N₂O. The median number of days from a DP to a JI with N₂O was 0 (range 0-87 days). 62 patients had JIs within 2 weeks; 11 between 2 and 4 weeks; 2 between 4 to 6 weeks; and, 3 after 6 weeks from DP. One patient receiving a JI after 6 weeks (87 days) from DP required imaging to confirm synovitis before proceeding with the procedure. Reasons for other JIs performed after 6 weeks from DP were unable to be elicited from charts. Documentation of a DP for JIs with N­₂O was present in 77/79 patients (97.5%).

Joints most commonly injected were: knees (80.05%), ankles (14.4%), elbows (3.28%), wrists (1.26%), subtalar (0.5%), fingers (0.31%) and shoulders (0.20%). There were no major adverse events (including septic arthritis) reported.  An increase in trainee procedures was seen after 2009 consistent with the introduction of a paediatric rheumatology (PRh) training program.  

Conclusion: Use of N₂O for JIs in children with JIA allows for expeditious, safe and efficient sedation and analgesia. At our centre, children assessed in clinic and who need JIs may be offered one at that visit, performed by the PRh team (clinician and nurse specialist).  This has benefits for clinical care (rapid access to the procedure); the patient and family (less time off school/college or work, no anaesthetic risk); health care costs (reduced need for day case access and theatre time); and, optimal use of resources (preferential access to general anaesthetic lists for younger children; or those requiring multiple JIs or use of image intensifiers; or, quick procedures reducing PRh time).

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/inhaled-nitrous-oxide-facilitates-access-to-intra-articular-corticosteroid-injections-in-children-with-juvenile-idiopathic-arthritis/