Self-administered mixture of Entonox and isoflurane in labour

Arora, Sonali; Tunstall, M.E.; Ross, Jane

doi:10.1016/0959-289x(92)80006-e

Cited by 21 publications

(6 citation statements)

References 16 publications

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“…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. The addition of isoflurane 0.2% or 0.25% to Entonox (premixed nitrous oxide : oxygen, 50/50, v/v) has been shown to provide more relief of pain from the contractions of labour than Entonox alone [1,2]. Such studies, however, have necessitated administration of the agent by an anaesthetist present in the labour room.…”

Section: Discussionmentioning

confidence: 99%

“…The mothers were informed that they themselves were free to switch from IN 2 O back to Entonox whenever they wanted. The selection of mothers for IN 2 O was left to the discretion of the midwives. Midwives were instructed that IN 2 O was a more potent inhalational analgesic than Entonox and could be used, if they so wished, to supplement analgesia in labour when Entonox seemed to be ineffective.…”

Section: Methodsmentioning

confidence: 99%

“…Accordingly, one might expect IN 2 O to have been used in the more painful types of labour. While it was not the object of this observational study to make comparisons with a control group it is of interest to consider the subjects in relation to figures typical of the rest of the labouring population (Table 7) taken from the Aberdeen Maternal and Neonatal Databank at the time of this study.…”

Section: J a S Ross Et Almentioning

confidence: 99%

“…If the standard precautions are taken regarding cylinder storage and layering of the gas mixture is prevented, the oxygen cannot run out ahead of the other constituents, unduly high concentrations of active agent cannot be given and no mixing valves are required [4]. The demonstration of an improved level of analgesia for IN 2 O in comparison with Entonox under the necessarily controlled environment of the trials to date [1,2] does not show that the addition of isoflurane to Entonox would be either safe or practical in the management of pain during labour in day-to-day midwifery practice. We therefore describe here the clinical course of 221 cases of selfadministration of premixed IN 2 O in labour under the control of the attendant midwife without direct supervision by medical staff.…”

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confidence: 99%

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The use of 0.25% isoflurane premixed in 50% nitrous oxide and oxygen for pain relief in labour

et al. 1999

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SummaryThe 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 twentyone 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. The addition of isoflurane 0.2% or 0.25% to Entonox (premixed nitrous oxide : oxygen, 50/50, v/v) has been shown to provide more relief of pain from the contractions of labour than Entonox alone [1,2]. Such studies, however, have necessitated administration of the agent by an anaesthetist present in the labour room. Accordingly, we have premixed isoflurane with Entonox as a 0.25% vapour to form a stable and homogenous gas mixture stored at 13.7 MPa (IN 2 O) [3]. This mixture can be self-administered by women in labour using the same equipment as is required for Entonox. As in the case of Entonox, the premixture of any self-administered analgesic or sedative inhalational agents increases safety when used under the supervision of a nurse or paramedic. If the standard precautions are taken regarding cylinder storage and layering of the gas mixture is prevented, the oxygen cannot run out ahead of the other constituents, unduly high concentrations of active agent cannot be given and no mixing valves are required [4]. The demonstration of an improved level of analgesia for IN 2 O in comparison with Entonox under the necessarily controlled environment of the trials to date [1, 2] does not show that the addition of isoflurane to Entonox would be either safe or practical in the management of pain during labour in day-to-day midwifery practice. We therefore describe here the clinical course of 221 cases of selfadministration of premixed IN 2 O in labour under the control of the attendant midwife without direct supervision by medica...

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Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: J a S Ross Et Almentioning

confidence: 99%

mentioning

confidence: 99%

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The use of 0.25% isoflurane premixed in 50% nitrous oxide and oxygen for pain relief in labour

et al. 1999

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“…Nitrous oxide has a quick onset, a short duration of effect, and is certainly more effective than TENS or pethidine (Table 1), although it is commonly used with the latter drug. Even with Entonox, the analgesia is often rated as poor by the mother during labour (Holdcroft & Morgan 1974), but it may be enhanced by the addition of a volatile agent (Levack & Tunstall 1984; Arora et al 1992). Nitrous oxide is by no means free from side effects.…”

Section: Types Of Pain Reliefmentioning

confidence: 99%