This chapter discusses the diagnosis, evaluation and management of shock. It presents special circumstances which make diagnosis and management of shock difficult in pediatric and pregnant patients. Shock should be suspected when patients present with a constellation of signs including ill-appearance, tachycardia, tachypnea, hypotension, and oliguria. The principles of shock management include specific therapy for treating the underlying cause, and general therapy to manage the shock syndrome. Recognition of shock is difficult due to variations in age-dependent vital signs, difficulty in assessing mental status, and the non-specificity of early manifestations of shock such as irritability and poor feeding. Elderly patients experience significantly more morbidity and mortality from all causes of shock due to their limited ability to augment cardiac output and maintain vascular tone. Elderly patients often have multiple comorbidities or use multiple medications that distort the diagnosis and management of shock.

The well-being of the fetus is strongly influenced by the status of the critically ill mother. Understanding basic principles of placental gas exchange is important when caring a pregnant patient in the intensive care unit (ICU). Aside from the few cases in which delivery is the preferred therapy, managing a pregnant patient in ICU should focus primarily on maternal well-being and only secondarily on the effects of interventions on the fetus. If preterm delivery is anticipated, administration of antenatal corticosteroids to the mother will decrease rates of common complications of prematurity of the newborn. The usual rule is to optimize the maternal medical condition and allow the fetus and placenta to take care of themselves. Certain fetal conditions such as severe intrauterine growth restriction may also provide a reason to separate the fetus from the mother.

Ethics is an essential dimension of maternal critical care. This chapter commences with a definition of ethics, medical ethics, and the fundamental ethical principles of medical ethics: beneficence and respect for autonomy. The ethical concept of the fetus as a patient is essential to maternal critical care in all cultural and national settings. Maternal critical care is ethically more complex when the fetus is a patient. After viability, discontinuation of critical care management should include delivery of the fetal patient. Preventive ethics uses the informed consent process to anticipate and prevent ethical conflict between patients and their physicians. The physician's role is to explain to the pregnant patient before critical care is initiated its nature as a trial of management. The advantage of the durable power of attorney for healthcare is that it applies only when the patient has lost decision-making capacity, as judged by his or her physician.

This chapter deals with issues related to mechanical ventilation in general and considers those relevant to the obstetric patient in particular. The most common modes of mechanical ventilation are: volume-controlled continuous mandatory ventilation (VC-CMV), pressure-controlled continuous mandatory ventilation (PC-CMV), intermittent mandatory ventilation (IMV), continuous mandatory ventilation (CMV), airway pressure release ventilation (APRV) and positive end-expiratory pressure (PEEP). All patients receiving mechanical ventilation should be monitored by pulse oximetry. Non-invasive ventilation can be delivered nasally or by face mask, using either a conventional mechanical ventilator or a machine designed specifically for this purpose. The 2009 H1N1 influenza pandemic and the particular susceptibility of pregnancy in such circumstances reinforce the need to appraise the rationale for mechanical ventilation in such patients. Finally, APRV as a ventilatory paradigm, in particular, may be particularly useful in the pregnant patient with pneumonits, acute lung injury, or acute respiratory distress syndrome (ARDS).

There is little evidence base for pregnancy-specific management of endocrine crises, and in the majority of cases the underlying condition should be treated as it would be outside of pregnancy, with no need for immediate delivery. Thyroid storm is associated with an increased risk of preterm labor, and staff in the critical care setting should be aware of this, along with the signs and symptoms of labor. Myxedema coma is a challenge to diagnose because of its insidious onset and lack of classic signs and symptoms. Acute adrenal crisis in the pregnant patient, if left untreated, is associated with high risk of maternal and fetal mortality. If labor coincides with pituitary apoplexy, steroid administration and correction of electrolyte imbalances are essential. In pregnancy, diabetic ketoacidosis (DKA) and the hyperosmolar hyperglycemic state (HHS) typically occur in the second and third trimesters, affecting an estimated 1-2 percentage of pregnancies.

Analgesia and sedation are frequently used in intensive care unit (ICU) patients. Appropriate analgesia is of great importance in ICU patients. Fentanyl is the most frequently used drug for this purpose but can lead to a substantial overhang after prolonged administration. Remifentanil is a promising alternative with a stable context-sensitive half-life. Agitation is the most frequent reason to sedate the patient, and the drug of choice is usually midazolam. There is a growing trend to use propofol in ICU sedation. Propofol has the advantage of less accumulation and, therefore, has a more stable context-sensitive half-life. Although propofol seems to be an almost ideal sedative, there is concern about the propofol infusion syndrome. Volatile anesthetics are frequently used for anesthesia in pregnant patients. More recently, volatile anesthetics have also been used for sedation in the ICU.

Neurosurgery during pregnancy is rare and as a result there are few evidence-based recommendations in the literature to provide guidance. An understanding of maternal physiology and a multidisciplinary approach are imperative to ensure a successful outcome. This chapter presents a case study of a 37-year-old female with multiple hematologic co-morbidities presented at 18 weeks gestation with perioral and periocular twitching, memory lapses and a recent sensory loss and painful paresthesias affecting the right side of her body. After a multidisciplinary discussion involving neurosurgery, obstetrics, and hematology it was decided to proceed with intracranial aneurysm clipping via craniotomy at 18 weeks gestation. A smooth intravenous rapid sequence induction with cricoid pressure was performed using lidocaine, fentanyl, propofol, and succinylcholine. Neurosurgery in a pregnant patient is rare and requires a thorough understanding of the physiologic changes of pregnancy and the associated concomitant anesthetic risks to both mother and fetus.