[Utilization of an equimolar mixture of oxygen-nitrous oxide in a general pediatric ward]

A review of the safety of 50% nitrous oxide/oxygen in conscious sedation

Few studies into conscious sedation with 50% nitrous oxide/oxygen premix (50% N2O/O2) have been conducted in accordance with Good Clinical Practice in Clinical Trials. Of the 140 articles retained in this review, the incidence of adverse events (AEs) varied in the range of 0-68% according to the indications. When other drugs and/or local anaesthesia were used concomitantly, the relative risk for nausea and vomiting increased whereas it decreased for vertigo or hallucinations. Only one study examined potential causal relationship between serious AEs and the 50% N2O/O2 gas itself, giving a risk for a serious AE directly due to the gas of 3/10,000 administrations. No analysis of the effect of the method of administration was possible, nor could conclusions be drawn relating to the risk of occupational exposure.

The Efficacy of Premixed Nitrous Oxide and Oxygen for Fiberoptic Bronchoscopy in Pediatric Patients

STUDY OBJECTIVE

s: The aim of the study was to evaluate the efficacy and safety of premixed 50% nitrous oxide and oxygen on the quality of sedation and pain control during fiberoptic bronchoscopy (FB) in children.

DESIGN

A prospective, randomized, double-blind study.

SETTING

Pediatric pulmonary department in a pediatric tertiary university hospital.

PATIENTS

One hundred five children aged 1 month to 18 years.

INTERVENTIONS

Patients inhaled after sedation and local anesthesia either premixed 50% nitrous oxide and oxygen (nitrous oxide group) or premixed 50% nitrogen and oxygen (control group) during FB.

MEASUREMENT AND RESULTS

The rate of failure was significantly greater in the control group (62%) than in the nitrous oxide group (21%, p = 0.00003). The efficacy of premixed 50% nitrous oxide and oxygen was also demonstrated with higher satisfaction scores (p = 0.000001), lower Children's Hospital of Eastern Ontario Pain Scores (p = 0.002), better visual analog scale ratings (p = 0.03), and improved behavior scores. Side effects were minor and similar in both groups.

CONCLUSIONS

This study demonstrates the improved efficacy of sedation, pain control, and safety of premixed 50% nitrous oxide and oxygen for FB in children.

Nurse administered relative analgesia using high concentration nitrous oxide to facilitate minor procedures in children in an emergency department

AIMS

To describe the experience of using high concentration nitrous oxide (N(2)O) relative analgesia administered by nursing staff in children undergoing minor procedures in the emergency department (ED) and to demonstrate its safety.

METHOD

Data were collected over a 12 month period for all procedures in the ED performed under nurse administered N(2)O sedation. All children greater than 12 months of age requiring a minor procedure who had no contraindication to the use of N(2)O were considered for sedation by this method. The primary outcome measure was the incidence of a major complication namely respiratory distress or hypoxia during the procedure. Secondary outcome measures were minor complications and the maximum concentration of N(2)O used.

RESULTS

Data were collected for a total of 224 episodes of nurse administered N(2)O sedation over a 12 month period. In 73.2% of children no complications were recorded. One major complication was recorded (respiratory distress) and the most common minor complication was mask intolerance in 17%. The mean maximum concentration of N(2)O used was 60.2%.

CONCLUSIONS

N(2)O is a safe analgesic in children over the age of 1 year undergoing painful or stressful procedures in the ED. It may safely be administered in concentrations of up to 70% by nursing staff after appropriate training.

Effective reduction of anxiety and pain during venous cannulation in children: a comparison of analgesic efficacy conferred by nitrous oxide, EMLA and combination

BACKGROUND

EMLA cream is the current technique of choice to reduce pain during venous cannulation in most paediatric practice. Its use is limited by logistic arrangements and failure to improve cooperation and allay anxiety. Nitrous oxide (N2O) would appear to be an effective alternative. A combination technique may be useful in selected patients.

METHODS

One hundred and twenty unpremedicated ASA 1 and 2 day surgery patients, aged 8-15 years were randomized into group 1 (EMLA + air/O2), group 2 (50% N2O/50% O2) and group 3 (EMLA + 50% N2O/50% O2). All patients underwent cannulation on the dorsum of the hand with a 22-G intravenous catheter. Pain behaviour before cannulation was assessed by an observer with Children's Hospital of Eastern Ontario Pain Scale (CHEOPS). Pain during cannulation was evaluated with CHEOPS by an observer and Visual Analogue Scale (VAS) (0-100 mm) by the patient. Satisfaction score (0-100%) for the experience were reported by the patient. Degree of ease of cannulation, time for cannulation were assessed. Heart rate, oxygen saturation were compared before, during and after cannulation.

RESULTS

The self-reported VAS for group 3 (10.10 +/- 14.99) was significantly lower than group 1 (26.13 +/- 27.59) and group 2 (18.35 +/- 18.11) (P = 0.003). No significant difference existed between VAS for group 1 and 2. There were also significantly more patients with VAS = 0 in group 3 (23/40) versus group 2 (11/40) versus group 1 (10/40), P = 0.004. The satisfactory score in group 3 (93 +/- 9.96) was significantly higher (P = 0.039) than group 1 (81.13 +/- 24.61) and group 2 (84 +/- 22.02). The increase in CHEOPS from before to during cannulation was significant only in group 1 (P = 0.002). There was no significant difference between frequency of patients with side-effects, ease of cannulation and time taken for cannulation in the three groups.

CONCLUSIONS

EMLA and 50% N2O are equally effective for pain reduction while a combination technique provides superior analgesia and satisfaction. N2O has an advantage over EMLA in reduction of pain related behaviour in older children.

Nitrous oxide exerts age-dependent antinociceptive effects in Fischer rats

Nitrous oxide (N(2)O) is an inhalational anesthetic/analgesic gas that has been used for clinical practice for more than a century. While its anesthetic mechanisms remain largely unknown, the underlying analgesic mechanisms are now being unraveled. It has been proposed that N(2)O induces opioid peptide release in the midbrain, leading to the activation of descending noradrenergic inhibitory neurons, which modulates pain processing within the spinal cord. Because descending noradrenergic inhibitory neurons are not functional at birth we posit that N(2)O only becomes an effective analgesic/antinociceptive agent in young patients when the descending noradrenergic inhibitory neurons become fully functional. In the present study, we have examined the age-dependence of N(2)O-induced antinociceptive effects on the formalin test. Fischer rats of various ages (7-, 15-, 19-, 23-, and 29-day-old, and adult) were injected 5% formalin into the hind paw during exposure to 75% N(2)O. Both their behavioral responses and changes in Fos-like immunoreactivity in the spinal cord were assessed as markers of N(2)O's antinociceptive effect. Adult-like antinociceptive responses to N(2)O, both behaviorally and immunohistochemically, were only present in rats older than 3 weeks (23- and 29-day-old). These findings support our hypothesis that N(2)O lacks antinociceptive effects in the very young animals.

[Analgesia with oxygen-nitrous oxide mixture during percutaneous renal biopsy in children]

The efficacy of an inhaled equimolar mixture of nitrous oxide and oxygen (Entonox/MEOPA) to prevent procedural pain during renal percutaneous biopsies in children was assessed.

PATIENTS AND METHODS

One hundred and seven children who underwent 113 renal biopsies during a 17-month period were included in a prospective uncontrolled pediatric study. Efficacy was evaluated using patients' answers to a questionnaire and nurses' observations.

RESULTS

Pain was absent in 86.5% of the cases. Mild adverse events were noted in one-third of the procedures, and were always reversible within a few minutes when the inhalation stopped. Acceptability was good. The use of this gas is easy and safe provided a few precautions are observed.

CONCLUSION

Inhaled equimolar mixture of nitrous oxide and oxygen prevents procedural pain during renal percutaneous biopsies.