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Nausea and Vomiting

Definition Nausea is defined as a subjective feeling of unpleasant sensation of urge to vomit. Vomiting is defined as dynamic expulsion of stomach contents from the mouth. Variants Retching is defined as strenuous, spasmodic, and periodic contractions of the respiratory muscles (diaphragm and muscles of the chest and abdominal wall) without expulsion of the stomach contents. Postoperative nausea and vomiting (PONV) is a common complication following…

Hypothermia

Hypothermia is characterized by fall of at least 1 °C below normal core temperature. This becomes clinically relevant when the core temperature starts to fall below 36 °C. This usually occurs either with a decrease in heat production, an increase in heat loss, or with dysfunctional thermoregulation. The maximum fall of temperature ranges from 2 to even 6 °C. This is a common but preventable complication…

Hazards of Advanced Neuromonitoring

Physiologic monitors are tools that enable the “vigilance” described in the motto of the American Society of Anesthesiologists (ASA) and guide the patient “safety” ( securitas ) in the motto of the Association of the Anesthetists of Great Britain and Ireland. The term is derived from monere , which in Latin means to warn, remind, or admonish. In perioperative care, monitoring implies the following four essential…

Anaphylaxis

Definition The term “anaphylaxis” infuses a sense of dread irrespective of place or person but with proper information in place, it can be treated in time. The European Academy of Allergology and Clinical Immunology defines anaphylaxis as “a severe, life-threatening, generalized, or systemic hypersensitivity reaction” primarily mediated by type E immunoglobulin (IgE), while the National Institute of Allergy and Infectious Disease/Food Allergy and Anaphylaxis Network symposium…

Postcraniotomy Pain

Definition Acute postoperative pain is defined as the pain occurring within first 24–48 h after a craniotomy. In a pilot study, De Benedittis et al. found that 60% of postcraniotomy patients suffered from moderate to severe postoperative pain. In two-thirds of the patients, the intensity of pain was moderate to severe. Pain was mainly seen in the first 48 h after surgery, with subtemporal and suboccipital craniotomies…

Pain Following Spinal Surgery

After a spinal surgery, acute pain is mainly generated from the skin, muscle, vertebrae, intervertebral discs, and facet joints. Following a spine surgery, most of the patients may have moderate to severe pain for the initial 3–4 days. The intensity of pain generated depends on the number of levels operated. There seems to be no difference in the severity of pain, according to the region of…

Syndrome of Inappropriate Antidiuretic Hormone Secretion (SIADH)

Definition Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is caused by excessive or inappropriate secretion or action of antidiuretic hormone (ADH), resulting in: Dilutional hyponatremia without clinically apparent hypervolemia (also known as euvolemic) Reduced plasma osmolality Impaired water excretion with decreased volumes of urine that is inappropriately concentrated for the prevailing plasma osmolality and volume status. Schwartz first described SIADH in 1957 (also known as Schwartz–Bartter…

Diabetes Insipidus

Definition Diabetes insipidus (DI) is a heterogeneous condition characterized by polyuria and polydipsia caused either due to a lack of secretion of vasopressin (antidiuretic hormone) from posterior pituitary, its physiological suppression following excessive water intake, kidney resistance to its action, or its increased degradation. DI is a rare condition, with a reported prevalence of 1 in 25,000. The impaired water conservation in DI leads to hypernatremia…

Cerebral Salt Wasting

Definition Cerebral salt wasting (CSW) is a condition characterized by renal loss of sodium leading to hyponatremia and concomitant decrease in extracellular fluid volume due to an intracranial disease. CSW was first described in 1950 by Peters et al. They reported three patients with intracranial disorder exhibiting renal salt wasting. In patients with intracranial disorders, hyponatremia is frequently attributed to syndrome of inappropriate hormone secretion (SIADH). However,…

Osmotic Demyelination Syndrome

Osmotic demyelination syndrome (ODS) refers to demyelination of white matter tracts traversing the pons (central pontine myelinolysis (CPM)) or in the extrapontine regions (extrapontine myelinolysis (EPM)). CPM is a noninflammatory, symmetric, demyelinating condition involving the central pons. EPM refers to demyelination, which occurs in the region outside the pons including midbrain, thalamus, basal ganglia, internal capsule, lateral geniculate bodies, cerebellum, and spinal cord. It is seen…

Stridor

Introduction The term stridor is derived from the Latin word stridere , meaning a harsh creaking or grating sound. It is a manifestation of a disordered airway due to air flow changes within the larynx, trachea, and bronchus. The frequency and quality of sound may vary from case to case. However, it should be differentiated from other voluntary or involuntary vocalizations such as bubbling of the…

The Difficult Pediatric Airway

Pediatric Airway Anatomy and Implications The pediatric airway is both anatomically and physiologically different from the adult airway in many ways. These differences are most important in children under two years of age and decrease as the child matures. Understanding of pediatric airway anatomy is crucial to the safe care of children under anesthesia. Anatomic differences in the pediatric airway include the fact that children have…

Difficult Airway in the Neurosurgery Patient

Definition Airway management is a core competency in anesthesiology, and a number of philosophies, algorithms, and tools have been established. Furthermore, airway management is influenced by the interaction between the clinical setting, patient factors, and practitioners’ skills. A common definition is that a difficult airway is one in which a conventionally trained anesthesiologist experiences difficulty with mask ventilation, tracheal intubation, or both. Although we are aware…

Intraoperative Increased Airway Pressure

Introduction Monitoring of the airway pressure is important during neurosurgical operations. Due to a variety of positions used during neurosurgery, there is a high risk of kinking endotracheal tubes (ETTs). Often, a slight increase in the airway pressure is the only sign that denotes recovery from neuromuscular blocking agents, necessitating the additional dose of these agents. Clinically, it presents as a tight bag, where it is…

Neurogenic Pulmonary Edema

Introduction Pulmonary edema is characterized by an accumulation of fluid in the air spaces and interstitium of the lung. It may be due to intrinsic pathology of the lung or due to systemic factors. Hence, pulmonary edema has been traditionally classified into cardiogenic and noncardiogenic causes. Cardiogenic pulmonary edema ensues due to acute left ventricular failure, following a variety of insults like myocardial infarction. Noncardiogenic pulmonary…

Hypoxia

Hypoxia is a serious complication that continues to be a leading cause of morbidity and mortality, especially in anesthesia-related events. There are many potential causes of perioperative hypoxia, and airway management is one of the most common. To diagnose, treat, and prevent these events, it is necessary to understand the various causes and effects of hypoxia, especially on the neurological system. Monitoring for diagnosis and prevention…

Hypercapnia

Definition and Etiology A carbonic dioxide arterial blood level (PCO 2 ) above 46 mmHg (6.1 kPa) is defined as hypercapnia. The increase in carbon dioxide (CO 2 ) partial pressure provokes a fall in blood pH, and its clinical features can be arterial hypertension, tachycardia, drowsiness, tachypnea, and skin rush, among other symptoms. An increase in CO 2 production or a decrease in its excretion…

Thromboembolism

Deep vein thrombosis (DVT) occurs in deep large veins of lower extremities and rarely in upper limbs. With the enlargement of thrombus, an embolus may get dislodged and be trapped in lungs resulting in pulmonary thromboembolism (PE). This leads to impaired perfusion but normal ventilation resulting in intrapulmonary shunting. The right ventricle, in turn, attempts to maintain the pulmonary perfusion by overcoming the elevated pulmonary vascular…

Postoperative Hematoma

Definition Development of a postoperative hematoma is a common complication after intracranial surgery; the gravity depends on the amount of collected blood. Some amount of blood may be frequently seen on subsequent scan in almost 10.8–50% of operated patients. For practical purpose, we define postoperative hematoma as intracranial collection of blood following craniotomy which is clinically symptomatic and requires evacuation. On this basis, the incidence varies…

Coagulopathy

Definition Coagulopathy is defined as a condition in which the blood’s ability to clot is impaired. Sometimes the term is used to represent both hypocoagulability and hypercoagulability. In this chapter we will be limiting our discussion primarily to hypocoagulability. Causes The normal coagulation cascade at a localized site seals any breach in vascular continuity and limits blood loss. Failure of this process to advance places the…