Maternal hypoxaemia associated with the use of Entonox in labour

Multimodal Acute Pain Management in the Parturient with Opioid Use Disorder: A Review

The opioid epidemic in the United States has led to an increasing number of pregnant patients with opioid use disorder (OUD) presenting to obstetric units. Caring for this complex patient population requires an interdisciplinary approach involving obstetricians, anesthesiologists, addiction medicine physicians, psychiatrists, and social workers. The management of acute pain in the parturient with OUD can be challenging due to several factors, including respiratory depression, opioid tolerance, and opioid-induced hyperalgesia. Patients with a history of OUD can present in one of three categories: 1) those with untreated OUD; 2) those who are currently abstinent from opioids; 3) those being treated with medications to prevent withdrawal. A patient-centered, multimodal approach is essential for optimal peripartum pain relief and prevention of adverse maternal and neonatal outcomes. Medications for opioid use disorder (MOUD), previously referred to as medication-assisted therapy (MAT), include opioids like methadone, buprenorphine, and naltrexone. These are prescribed for pregnant patients with OUD, but appropriate dosing and administration of these medications are critical to avoid withdrawal in the mother. Non-opioid analgesics such as acetaminophen and nonsteroidal anti-inflammatory drugs (NSAIDs) can be used in a stepwise approach, and regional techniques like neuraxial anesthesia and truncal blocks offer opioid-sparing options. Other medications like ketamine, clonidine, dexmedetomidine, nitrous oxide, and gabapentinoids show promise for pain management but require further research. Overall, a comprehensive pain management strategy is essential to ensure the well-being of both the mother and the fetus in pregnant patients with OUD.

Anesthesia considerations and post-operative pain management in pregnant women with chronic opioid use

The prevalence of opioid use disorder in pregnancy has escalated markedly in recent years. Chronic opioid use during pregnancy poses several challenges for providing adequate analgesia and anesthesia in the peripartum period. These challenges include the potential for withdrawal, opioid tolerance and opioid-induced hyperalgesia. Here we discuss alterations in analgesic pharmacokinetics and pharmacodynamics that are associated with chronic opioid use. In addition, when treating pain in patients with opioid use disorder it is important to distinguish between different subgroups. In this review, we will discuss practical management strategies for parturients with (1) untreated opioid use disorder, (2) parturients on medication-assisted treatment (methadone, buprenorphine) and (3) patients recovering from opioid use disorder that are currently abstinent. Finally, we offer an overview of non-opioid strategies that may be utilized as part of a multimodal approach to providing optimal analgesia in this patient population.

Nitrous oxide for labor analgesia

Inhaled nitrous oxide (N2O) has been used worldwide for over 100 years as labor analgesia but has not gained widespread use in the United States. Nitrous oxide provides a noninvasive option for laboring women. This article outlines its efficacy and safety as an analgesic compared with epidural and IV pain medications.

Should Nitrous Oxide Be Used for Laboring Patients?

Nitrous oxide, long used during labor in Europe, is gaining popularity in the United States. It offers many beneficial attributes, with few drawbacks. Cost, safety, and side effect profiles are favorable. Analgesic effectiveness is highly variable, yet maternal satisfaction is often high among the women who choose to use it. Despite being less effective in treating labor pain than neuraxial analgesic modalities, nitrous oxide serves the needs and preferences of a subset of laboring parturients. Nitrous oxide should, therefore, be considered for inclusion in the repertoire of modalities used to alleviate pain and facilitate effective coping during labor.

Nitrous oxide for labor analgesia: expanding analgesic options for women in the United States

Nitrous oxide (N2O) is a commonly used labor analgesic in many Western countries, but is used infrequently in the United States. The University of California at San Francisco has been offering N2O for labor analgesia for more than 30 years. Vanderbilt University Medical Center recently began offering N2O as an option for pain relief in laboring women. Many women report that N2O provides effective pain relief during labor and argue that it should be made more widely available in the United States. This article discusses the use of N2O for pain management during labor, including its history, properties, clinical indications, and use and environmental safety issues. Practical issues regarding implementation of N2O service in a medical center setting are also discussed.

Analgesia with sevoflurane during labour: I. Determination of the optimum concentration † ‡

BACKGROUND

Sevoflurane has favourable physical qualities for inhaled analgesia during labour pain. The aim of this preliminary study was to identify its optimum concentration.

METHODS

In this open-labelled escalating-dose study, 22 parturients in labour self-administered sevoflurane at 10 contractions using an Oxford Miniature Vaporiser. The inspired concentration was increased by 0.2% after each contraction from 0% to 1.4% or decreased if sedation occurred. Visual analogue scores (0-100 mm) for pain intensity, pain relief, sedation, mood and coping were measured after each contraction.

RESULTS

The median (IQR [range]) pain relief and sedation scores increased from 44 (43-56 [4-93]) mm and 55 (43-56 [0-98]) mm at 0.2% sevoflurane, to 74 (72-78 [50-80]) mm and 71 (71-73 [33-97]) mm at 1.2% sevoflurane, respectively. Pain relief scores did not show any significant increase above 0.8% whilst sedation continued to increase, with excessive sedation occurring at 1.2% sevoflurane. No significant changes in other scores were measured.

CONCLUSIONS

We concluded that the optimal sevoflurane concentration in labour was 0.8%. This concentration allows a safety margin and balances the risk of sedation with the benefit of pain relief in labour.

Intrauterine resuscitation: active management of fetal distress

Acute fetal distress in labour is a condition of progressive fetal asphyxia with hypoxia and acidosis. It is usually diagnosed by finding characteristic features in the fetal heart rate pattern, wherever possible supported by fetal scalp pH measurement. Intrauterine resuscitation consists of applying specific measures with the aim of increasing oxygen delivery to the placenta and umbilical blood flow, in order to reverse hypoxia and acidosis. These measures include initial left lateral recumbent positioning followed by right lateral or knee-elbow if necessary, rapid intravenous infusion of a litre of non-glucose crystalloid, maternal oxygen administration at the highest practical inspired percentage, inhibition of uterine contractions usually with subcutaneous or intravenous terbutaline 250 microg, and intra-amniotic infusion of warmed crystalloid solution. Specific manoeuvres for umbilical cord prolapse are also described. Intrauterine resuscitation may be used as part of the obstetric management of labour, while preparing for caesarean delivery for fetal distress, or at the time of establishment of regional analgesia during labour in the compromised fetus. The principles may also be applied during inter-hospital transfers of sick or labouring parturients.