Intravenous access in distressed children : effects of midazolam and nitrous oxide on success rate, hormone and metabolic stress responses

Abstract

Background and Aims: Intravenous (IV) access has demonstrated high levels of pain and distress in children. A stress full IV access should be avoided, primarily by the children, but also for the parents and staff. When testing children with suspected endocrine and metabolic disorders there is a substantial risk that a stressful IV access influences the hormone releases and metabolic response. The aims of this thesis were to facilitate painful procedures and IV access in children at a paediatric outpatient clinic. To study the feasibility, effects and stress response of Nitrous Oxide (N2O) compared to Midazolam and EMLA alone in children with endocrine disorders and obesity.

Material and Methods: Children with anxiety or previous difficulties establishing IV access were included (n=140). 50 children were openly randomised to EMLA (n=25) or EMLA+ N2O (n=25). 90 children (60 obese and 30 growth retarded) were double blinded randomised to; midazolam, 0.3mg/kg, max 15 mg, (n=30), 50% N2O (n=30), and to 10% N2O (n=30). A subgroup of 20 anxious children undergoing repeatedly painful procedures was also included. These children underwent two procedures with EMLA and EMLA+N2O, the order of priority being randomised.

Measurments: Number of attempts; defined both as the number required to succeed in setting up double IV lines, and as a successful IV line procedure with 2 attempts for two iv lines vs >2 attempts, IV access time; defined as time from start of setting up the IV lines until two IV lines were established. Recovery time; defined as the time from establishment of the IV lines until regained alertness. Total procedure time; defined as IV access time plus recovery time. Evaluations; children’s, parents’ and nurses’ satisfaction of the IV line procedure, Pain; evaluated by the child. Sedation levels; assessed using the Observer’s Assessment of Alertness/Sedation Score. Blood samples were obtained during 30 minutes at four time points after achieving venous access and, if possible, after 24 hours. 1; 0−1 min, 2; 5−6 min, 3; 14−15 min, and 4; 29−30 min. Analyses were compared between treatments and treatments over time. 60 children (40 obese and 20 growth retarded), served as controls.

Results: Comparing all study children together with IV access problems, a significant difference in number of attempts between the treatments groups were seen (P<0.001) with differences between midazolam compared with 50% N2O and EMLA compared with midazoalm, 10%, 50% N2O. The percentage of successfully IV line procedures were 70% using 50% N2O. The children’s evaluations were significantly more positive for 50% N2O during IV access and painful procedures. 50% N2O was more efficient measured as total procedure time (P<0.001) and especially in obese children an unfavourable long procedure time was observed after midazolam. Significantly lower cortisol levels were detected when midazolam was used compared to both 50% and 10% N2O and to unstressed controls. Glucose levels among growth retarded children increased from 0 to 30 min, whereas the opposite was found in obese children regardless of treatment. The growth hormone levels decreased with time in the midazolam group compared to 50% and 10% N2O, where the effect of time was reversed.

Conclusion: 50% N2O in combination with EMLA, was in all aspects superior to midazolam for facilitation of IV access for distressed children. The IV access procedure was more efficient, with a shorter total procedure time and an increased number of successful IV lines. Midazolam should only be used exceptionally in obese children due to the long recovery time. Treatment with N2O and midazolam influence the results of hormone analyses in the form of different levels and trends in glucose and stress hormones.