POTENTIAL COMPLICATIONS

•

Hypoxia. There are two possible causes for potential hypoxia when using Entonox. Firstly, it is noted that at the end of an anaesthetic procedure when nitrous oxide is stopped abruptly (and room air breathed), oxygen tension can fall as nitrous oxide loods the alveoli. This is known as ‘diffusion hypoxia’, and is generally a transient situation. Oxygen should be available to administer to the woman or neonate,

•

Understand and observe for the possible effects/side effects of multiple pharmacology, e.g. use of opioid analgesics concurrently.

•

Ensure that all records are contemporaneously kept including the duration of use, effects and possible side effects.

•

Ensure that all apparatus is cleaned/serviced and ready to use again on completion.

the cardiovascular system, e.g. pre-eclampsia; nervous system damage, e.g. muscular sclerosis; and

haematology changes, e.g. sickle cell anaemia. It is also noted that nitrous oxide can expand any existing pockets of gas within the body (BOC 2011). Anyone with known sinus or ear problems should use nitrous oxide with caution.

•

Fire risk. As for all combustible gases care should be taken to avoid sources of ire and any grease. This is pertinent in the home as well as medical

establishments.

•

Staff exposure. Robertson (2006) reiterates the need for occupational awareness of health and safety.

Maternity units should have effective ventilation and scavenger systems, staff should also consider wearing personal exposure monitors, particularly if working consistently on labour wards. Care should be taken to avoid standing in front of women when Entonox is being breathed out. Vitamin B12 can be inhibited with exposure to nitrous oxide and fertility may be affected. Robertson (2006) urges midwives who are planning to become pregnant to consider working in non-nitrous oxide environments.

PROCEDURE: using Entonox in labour

•

Ensure that the equipment is correct and working, that the midwife is trained in its use, and that the woman does not have any allergies or

contraindications.

•

Ensure also that the woman understands how Entonox is safely used and that she agrees to this administration.

•

Allow the woman to place the mouthpiece or mask in place.

•

With a hand on the uterine fundus, palpate for the presence of a contraction.

•

As the contraction begins, encourage the woman to breathe in the gas taking slow breaths with reasonable depth.

•

At the peak of the contraction encourage the woman to remove the mask/mouthpiece and to breathe normally in air (aim to stand at the side as she breathes out, rather than in front of her). Continue to assist the woman through that contraction in a way that helps her.

•

Observe and question the woman as to the effects of the gas, and any side effects, particularly as time passes.

•

Monitor all vital sign observations as for care in labour, ensuring that respiration rate and depth are noted. Consider the use of pulse oximetry if any observations are outside of normal parameters.

ROLE AND RESPONSIBILITIES OF THE MIDWIFE These can be summarized as:

• if appropriately trained in its use, the midwife may administer Entonox to labouring women – all stages of labour are permitted

• as a self-administered medication, the midwife has a signiicant role in ensuring that the woman uses it correctly, and in helping her to gain the maximum beneit

• as well as monitoring the woman’s vital signs as part of labour care, the midwife must monitor her respiration rate and depth, encouraging her to breathe slowly but with reasonable depth. Action should be taken should there be any signs or symptoms of overdose, hyperventilation or hypoxia

• full and contemporaneous records are kept

• the midwife should be fully aware of how to use, store and clean the apparatus (particularly if using a portable cylinder), and of how to ensure that potential faults are corrected

• Health and Safety at Work Regulations should be upheld with regard to nitrous oxide use. Midwives should consider their own safety.

SUMMARY

•

Due to the nature of its administration (i.e. the need to breathe early in each contraction) its effect as a labour analgesic can be variable, but it is appreciated by many women. The side effects for the women are transitory and there are no documented negative effects (at this time) for the fetus.

•

The midwife has responsibilities to ensure that it is stored, serviced and used correctly. The midwife should be alert to any signs of adverse reactions with its use.

•

Working in environments of extensive nitrous oxide use may pose health threats to employees. Health and Safety Regulations should be upheld.

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Principles of drug administration: inhalational analgesia: Entonox

REFERENCES

SELF-ASSESSMENT EXERCISES

The answers to the following questions may be found in the text:

1. Describe how a midwife should support a woman to use Entonox effectively in the irst and second stages of labour.

2. Discuss the advantages and disadvantages of Entonox as a labour analgesic.

3. Summarize the role and responsibilities of the midwife when caring for a woman using Entonox in labour.

4. a) Which vital sign observations should be undertaken regularly when a woman is using Entonox? b) Why?

BOC, 2008. New Zealand Data Sheet:

Entonox. BOC, Australia. Available online: <http://www.medsafe.govt.nz/

profs/datasheet/e/entonoxgas.pdf>

(accessed 1 March 2015).

BOC, 2011. Entonox: Essential Safety Information. BOC, Manchester.

Available online: <http://www .bochealthcare.co.uk/en/Products -and-services/Products-and-services -by-category/Medical-gases/

ENTONOX/ENTONOX.html>

(accessed 1 March 2015); (safety data sheet).

Green, J., 1993. Expectations and experiences of pain in labour:

indings from a large prospective study. Birth 20 (2), 65–72.

Jordan, S., 2010. Pain relief. In: Jordan, S.

(Ed.), Pharmacology for Midwives, second ed. Palgrave Macmillan, Basingstoke. (Chapter 4).

Nagele, P., Duma, A., Kopec, M., et al., 2014. Nitrous Oxide for treatment-resistant major depression: A proof-of-concept trial. Biol. Psychiatry Journal. Available online: <http://

www.biologicalpsychiatryjournal.com/

article/S0006-3223(14)00910-X/

fulltext> (accessed 3 January 2015).

NICE (National Institute for Health and Care Excellence), 2014. Intrapartum Care: Care of Healthy Women and their Babies during Childbirth. NICE, London. Available online:

<www.nice.org.uk> (accessed 5 March 2015).

Robertson, A., 2006. Nitrous oxide – no laughing matter. MIDIRS Midwifery Digest. 16 (1), 123–128.

Principles of drug administration: epidural analgesia

Chapter

Postdural puncture headache (PDPH) 192

Catheter migration 192

Abscess formation 192

Haematoma 192

High regional/total spinal anaesthesia 193

Meningitis 193

Effect on labour 193

PROCEDURE: siting an epidural catheter

and analgesia 194

Checking the level of the block 195 Intermittent epidural bolus

administration 195

PROCEDURE: manual intermittent

epidural bolus administration 197 PROCEDURE: removing an epidural

catheter 197

Postnatal care 197

Role and responsibilities of the midwife 198

Summary 198

Self-assessment exercises 198

References 198

LEARNING OUTCOMES

Having read this chapter, the reader should be able to:

•

discuss the differences between epidural, spinal and combined spinal epidural analgesia

•

list the indications and contraindications for epidural analgesia

25

CHAPTER CONTENTS

Learning outcomes 186

The epidural space 187

Epidural analgesia 188

Low-dose ‘mobile’ epidural 188

Spinal analgesia 188

Combined spinal epidural analgesia 188

Drugs 188

Continuous versus intermittent drug

administration 189

Indications for epidural analgesia 189

Contraindications 189

Absolute 189

Relative 189

Side effects of epidural analgesia 189 Management of side effects 190

Respiration depression 190

Sedation 190

Nausea and vomiting 190

Pruritus (itching) 190

Urinary retention 190

Hypotension 190

Leg weakness 190

Drug toxicity 191

Complications 191

Partial block (‘breakthrough’ pain) 191

Dural puncture 191

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