Recent Advances in Anesthesiology

Anesthesia during pregnancy is challenging due to the extreme physiological and anatomical changes that occur. Deep knowledge of these changes and how they influence anesthesia is critical in order to offer safe anesthetic care to both, mother and the child. In this chapter, we will review the main features that occur in the respiratory, cardiovascular, central nervous, renal, and gastrointestinal systems, among others, and how it affects pharmacodynamics, pharmacokinetics, airway management and conduct of anesthesia. Fetomaternal circulation and fetal physiology focused on anesthesia will also be discussed. 

The principal goal of health systems is to provide safe and quality healthcare for the patient. Deficiencies in the environment in which obstetric care is provided, inadequate teamwork and communication, and poor individual performance during emergencies have been identified as preventable causes of harm to obstetric patients. There is growing evidence about training in Emergency Obstetric Care (EmOC) that reduces the risk of maternal and newborn mortality and morbidity. The Institute of Medicine identifies team-based training and simulation as methods to improve patients’ safety, especially in the obstetrics field, these may add value to it. Recent research works review the effectiveness of training in EmOC and the use of simulation in improved health outcomes. It remains unclear whether this translates into improved patient outcomes.

Airway management in the obstetric patient is a challenge for anaesthesiologists, not only because of the anatomical and physiological changes during pregnancy, but also because of the surgery´s urgency, the location of the procedure, which sometimes takes place even outside the operation theatre, and also due to conflicts emerging between the needs of the mother and fetus. The arising maternal comorbidities such as obesity, contribute to complications in airway management in this population.

Fetal surgery has evolved in the last decades, mostly because of the technical advances in therapeutic and monitoring devices. The timing and mode of surgery depend on the disease to be treated. Local, neuraxial or general anesthesia can be used on the mother. In some cases, fetal analgesia and paralysis are needed. The idea of treating the fetus as a patient has evolved in recent years, as a consequence of improvements in diagnostic imaging and surgical devices. In fetuses with congenital airway obstruction, intrapartum surgical correction or airway management can be performed while maintaining perfusion via the umbilical cord. In 1980, maternal laparotomy and hysterotomy were proposed to treat fetuses with congenital and developmental abnormalities, and the prerequisites for maternal-fetal surgery were first formulated in 1982. They are still in use with some minor modifications. A multidisciplinary approach to fetal intervention is essential. Both obstetric and pediatric anesthesia is involved and it a close collaboration with surgical teams is necessary.

Labour pain is a complex phenomenon involving subjective psychological factors and physiological neurohormonal factors. Many different factors contribute to the perception of pain: cultural factors, bond, and trust in the delivery team, being able to take their own decisions, relaxation ability, previous labour, anatomical and fetalrelated factors. Pain relief is one of the elements involved in overall satisfaction but it is not the only one and is important to remember that pharmacological intervention is only a part of it.

The choice of drugs used during labor is almost as important as the analgesic technique selected since effective pain relief contributes directly to satisfaction: the better the pain relief, the higher the satisfaction. Although bupivacaine has traditionally been the most widely used local anesthetic, L-bupivacaine and ropivacaine have similar action profiles with a lower risk of cardiovascular and neurologic toxicity and especially less motor blockade, when used under low-concentration strategies. The use of adjuvants, especially opioids, allows us to improve the analgesic quality while reducing the total dose of local anesthetics, although their use should be individualized, and patients should be monitored and treated for side effects if they appear. 

Caesarean section is the most frequently performed surgery in adults, with a total of 20 million procedures per year. More than 70% of cases are due to lack of labor progression, fetal distress, breech presentation or previous cesarean section. Obstetric anesthesia practice has substantially changed over the last 20 years. The main cause of this is the introduction of regional techniques to the detriment of general anesthesia, which has reduced maternal mortality due to complications such as gastric aspiration or difficulty in orotracheal intubation. In general, we can affirm that regional anesthesia is the most frequently used anesthetic technique for cesarean section, reserving general anesthesia for urgent or life-threatening situations.

Labor pain is associated with increased stress response and when it is excessive, it may lead to hypoxemia and fetal acidosis. The most important factor in obstetric analgesia is the desire for pain relief by the patient and neuraxial analgesia is the mainstay procedure in labor and in anesthesia for cesarean delivery. Continuous lumbar epidural analgesia is the mainstay of neuraxial labor analgesia. There are other methods, such as intrathecal block or combined spinal-epidural, that can be useful in specific cases. Despite being the safest and most effective method, the epidural labor analgesia may have some complications. Other therapies include bilateral paracervical block and pudendal block, which provide rapid onset analgesia (2–5 min). Although useful, they require training and are risky in cases of placental insufficiency or prematurity.

Postpartum haemorrhage due to uterine atony is one of the major causes of maternal morbidity and mortality worldwide. Different control strategies have been postulated, especially during the third stage of labour, but the gold standard treatment is the use of uterotonic drugs. There are currently three well-defined groups of drugs: oxytocics, ergot derivatives and prostaglandins. Although the literature is heterogeneous, it is clear that oxytocin is the uterotonic of choice in both prophylaxis and treatment of postpartum haemorrhage. Detailed knowledge of protocols based on current evidence is mandatory, which vary according to the different medical societies and dictate the doses and order of administration of different drugs.

The need for non-obstetric surgery during pregnancy is relatively frequent and can occur at any time during pregnancy. In this chapter, we will develop the anesthetic implications of changes in maternal physiology, and the repercussions of anesthesia on the fetus, and we will delve into the peculiarities of anesthetic management of these patients. Urgent/emergent procedures should not be postponed in these patients due to their pregnancy conditions. However, elective surgeries should be delayed whenever possible, taking into account the maternal-fetal risk-benefit. 

An increase in pregnant patients with comorbidities has been seen in the last decade. Nevertheless, these patients are able to enjoy longer and better quality lives nowadays. During pregnancy, patients can experience decompensations of their chronic disease which can be sometimes challenging for the medical team. Complexity has risen; that is why the anesthesiologist must be updated and capable of facing different scenarios both in the delivery room and before or after birth. This chapter offers a practical and synthetical approach to the most common situations in which a general anesthesiologist can be involved, aiming to emphasize main points for safe and accurate anesthetic care.

Fever is often the result of an infection. The most common sites for infection during pregnancy are fetal membranes, urinary and respiratory tracts, and the postpartum uterine cavity. The most frequent etiologies of intrapartum fever are chorioamnionitis and neuraxial anesthesia. Maternal and fetal exposure to hyperthermia and inflammation is associated with adverse consequences for the mother and the neonate. In pregnant women with fever, anesthesiologists are not only involved in providing analgesia, but also in the correct anesthetic management for the surgical treatment of the infectious region. Thus, as pyrexia may change both obstetric and anesthetic management, preventing maternal fever is imperative. Emerging and challenging infectious diseases, as COVID-19, remind us of the susceptible nature of pregnant and early postpartum women to severe respiratory infections, reinforcing the importance of vaccines and therapeutic measures during pregnancy.

Postpartum hemorrhage (PPH) is the most common cause of obstetric hemorrhage (OH) and the first cause of maternal death worldwide. However, its mortality has decreased in the United States in recent decades due to the implementation of certain measures. Several factors are significantly associated with the onset of PPH. Identifying them early will help us to establish an appropriate strategy for the management of these patients. One of the most useful prevention measures is the active management of the third stage of labor, especially the routine administration of oxytocin. The existence of acting algorithms will also contribute to a rapid and orderly response to the presence of expected or unplanned bleeding.

Due to the high risk of morbidity and mortality in pregnant women with unrecognised and untreated preeclampsia, a high index of suspicion for signs of preeclampsia should be used to evaluate, treat and monitor patients. Early blood pressure control and seizure prophylaxis during labour are essential to ensure maternal safety. However, a limited proportion of pregnancies and deliveries may present a wide range of complications that may require admission to a critical care unit (CCU). Hypertensive disorders of pregnancy and massive hemorrhage are among the most common causes of admission to the CCU in pregnant and post-partum women. 

Amniotic fluid embolism (AFE) is an uncommon pathology, whose incidence ranges from 2 to 8 per 100,000 births, depending on the country. This syndrome has four cardinal symptoms: circulatory collapse, respiratory distress, cyanosis and coma. If the patient survives cardiorespiratory failure, disseminated intravascular coagulopathy occurs, leading to incoercible bleeding and eventually death. Clinical diagnosis is based on Clark's four criteria: sudden cardiorespiratory arrest, established disseminated intravascular coagulation prior to bleeding, and all of these occurring peripartum in the absence of fever. The two main differential diagnosis syndromes are pulmonary thromboembolism and myocardial infarction. Treatment consists of cardiopulmonary support of the patient. Despite aggressive measures, such as the placement of ventricular assist devices and external oxygenation membranes, the prognosis continues to be poor. The main death cause is incoercible bleeding caused by disseminated intravascular coagulopathy.

The postpartum period is the time after delivery when physiological changes by the pregnancy return to the previous state. Primary postpartum haemorrhage takes place during the first 24 hours, and secondary postpartum haemorrhage occurs between 24 hours and 6 weeks after delivery. Many disorders can occur in the immediate postpartum period, there is a considerable source of morbidity and mortality in women of reproductive age, which can be mild to severe and life-threatening. Protocols aimed at the multidisciplinary management of postpartum haemorrhage, and together with the use of coadjuvant hemostatic agents, the activation of massive transfusion protocols in a responsible manner, and surgical management have improved the prognosis of these patients.

Chronic pain (CP) conditions after childbirth include persistent pain after caesarean section (CPCS), perineal pain after instrumental vaginal delivery, lower back pain and pelvic girdle pain. Any type of CP before or during pregnancy increases the risk of CP after delivery. Scar pain is the most recognized etiology for CPCS with a neuropathic component, although it is less frequent than in other surgeries. Reported CPCS incidence ranges from 1 to 23%. Pain intensity is moderate and decreases with time in all studies. The severity and duration of peripartum pain are the main risk factors for CP and its control is the most recommended strategy for reducing risk. Fear of fetal and neonatal adverse events means that CP is often undertreated, but after delivery, pharmacological restrictions disappear and many pain drugs are compatible with breastfeeding. Education of obstetric teams about early detection and referral to specialized consultation of women with CP is the key. In this chapter, available information in the recent literature, mainly during the last years, is presented. This chapter focuses on CP conditions after childbirth, as analgesia for labor and childbirth and immediate pain after CS and vaginal delivery are covered in other chapters of this book.

Infertility is a common aspect globally affecting couples to 15%, and it is frequently increasing the need for anesthesiologists’ participation in assisted reproductive techniques. Currently, the procedures used to assist reproduction are unable to fully cover the detrimental effects of age. During anesthesia-analgesia in oocyte retrieval, the role of the anesthesiologist is to provide the patient with adequate anxiolysis, analgesia, and sedation as the key to success in the procedure. An adequate pre-anesthetic assessment is required to identify derivative diseases and take the appropriate care of each patient. Modern anesthetic techniques for oocyte retrieval include conscious sedation, general anesthesia, regional anesthesia, and other alternative techniques, such as electroacupuncture, or even a combination of these. In this chapter, the main characteristics of these techniques will be exposed, as well as their complications and the recommendations so that anesthetic procedures are safe not only for the patient, but also for the whole process’ success.

Approximately 3% to 4% of term fetuses are in breech presentation, and this is a common indication for cesarean delivery. Twenty percent of elective cesarean sections are due to breech position. External cephalic version (ECV) is an obstetric maneuver that applies external pressure to the fetal posture through the maternal abdomen, to convert a breech presentation to a vertex presentation. Since the risk of adverse events after an ECV is small, the possibility of ECV should be offered in all pregnancies with breech presentation, provided that there is no contraindication. A standardized protocol, an experienced gynecologist and adequate analgesia can facilitate the maneuver and improve the success rate, turning the ECV into a maneuver with an excellent safety profile which is an interesting option to avoid a cesarean section. 

During pregnancy, events occur that can negatively affect a woman's mental health, such as vaginal bleeding, concern for the health of the fetus, decreased fetal movements, ultrasound results, or fear of childbirth itself. Pregnant women must be able to cope with these stressful events, as perinatal mental health problems can have adverse consequences for both parents and babies. Psychological disturbances in the mother during pregnancy can adversely affect the development of the fetus, leading to long-term negative effects on the health of the child. It is therefore important to identify prenatal interventions that can reduce this maternal distress, and one possible approach to address these perinatal mental health difficulties is mindfulness-based interventions.