The use of 0.25% isoflurane premixed in 50% nitrous oxide and oxygen for pain relief in labour
✍ Scribed by J. A. S. Ross; M. E. Tunstall; D. M. Campbell; J. S. Lemon
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 97 KB
- Volume
- 54
- Category
- Article
- ISSN
- 0003-2409
No coin nor oath required. For personal study only.
✦ Synopsis
The addition of 0.25% isoflurane to 50% nitrous oxide in oxygen provides more effective pain relief in labour than 50% nitrous oxide alone. This study was carried out to determine whether self‐administration by demand valve of 0.25% isoflurane in 50% nitrous oxide in oxygen premixed in cylinders at 13.7 MPa (IN~2~O) was practical and safe during labour. Two hundred and twenty‐one mothers used IN~2~O in labour after 50% nitrous oxide had become inadequate for pain relief. Data on IN~2~O use was recorded during labour and details of the course of labour and opioid usage were taken from the clinical notes. The duration of IN~2~O use was 0.1–12.35 h (median 2.3). Thirty‐two mothers (14.5%) required an epidural and intolerance to IN~2~O was seen in a maximum of 17 cases (7.7%). One hundred and twenty‐six cases were primiparous and 93 parous with 151 deliveries being spontaneous and 70 interventional, of which 12 were by Caesarean section. Maternal blood loss was 20–1500 ml (median 200 ml). Apgar scores at 1 and 5 min were unaffected by IN~2~O use although a positive correlation was found between the use of opioids and the number of neonates with a 1‐min score below 8 and the number requiring resuscitation. Six neonates had an Apgar score below 8 at 5 min, but their condition was adequately explained by factors other than the sedative technique used. Self‐administered IN~2~O was found to be a safe and practical technique for sedation in labour when 50% nitrous oxide alone had become inadequate.