bluuebunny/crossref_metadata_2025 huggingface dataset:
Pressure Measurement of Gases and Liquids
Authors: Aquino Ben
Published: May 2024

This chapter on the pressure measurement of gases and liquids seeks to aid the anesthesia provider in understanding how and why pressures are measured, and the factors that affect the data obtained. It looks at the manometer as a basic illustration of the principles of pressure measurement, and it also explains the measurement of partial pressures, and their clinical pertinence in anesthesia for the proper delivery of anesthetic gases. The chapter also explains transduction systems used to measure pressures, using the arterial line system as an example to show principles of measurement as well as factors affecting the quality and accuracy of the data obtained therein.
Components
Authors: Jun Charles , Nasr Ned F.
Published: May 2024

The various components in the delivery of anesthesia all play a vital role. Understanding the mechanism of each component helps operators understand the strengths and limitations of each component. This chapter discusses the properties of the main components involved in the delivery of the volatile anesthetic, including their advantages and disadvantages, along with clinical considerations intraoperatively. The components that are dissected in this chapter are the following: unidirectional valve, corrugated breathing tube, connectors, adaptors, facemasks, laryngeal mask airways, endotracheal tubes, reservoir bag, airway pressure relief valve, and the absorber.
Blood Pressure Monitoring Methods
Authors: Hithe Candice C. , Huebsch Jerome B.
Published: May 2024

Understanding the methods of blood pressure monitoring is an essential concept for the anesthesiologist. This chapter reviews the basic blood pressure monitoring methods, such as the palpatory, auscultatory, and Doppler techniques. These methods rely on the use of a sphygmomanometer (inflatable cuff with a pressure gauge). Their accuracy is dependent on the ability of the cuff to compress the artery reliably. The palpatory and Doppler techniques can only estimate systolic blood pressure. Both systolic and diastolic blood pressure can be estimated by listening for Korotkov sounds during the auscultatory approach. This chapter also explains the more advanced techniques, such as oscillometry and intra-arterial methods. With oscillometry, the mean arterial pressure is measured, and the systolic and diastolic blood pressures are less accurately calculated. Intra-arterial cannulation is considered the gold standard and gives the most accurate measurement of systolic, diastolic, and mean arterial pressures. The newer techniques, such as the volume clamp method and applanation tonometry, are also discussed.
Intravascular Pumps
Authors: Hagan Jack , Giordano Chris
Published: May 2024

Intravenous pumps have evolved since the 1600’s into important tools for anesthesia professionals to meet their anesthetic goals. Various pumps are available, including syringe, intravenous line with a manual resistance device or electronic pump, elastomeric, and even simple gravity by counting drops. These also range from powerless to electronically highly complex—with drug databases and electronic medical record connection. Each has its advantages; however, as with any device, there are complexities, and vigilance is needed to prevent patient harm. This chapter reviews types of pumps, factors involved in selection, and clinical examples in which pumps can lead to potential harm.
Pharmacokinetics and Pharmacodynamics
Authors: Parker Nicholas M. , Waqar Syed
Published: May 2024

Pharmacokinetics addresses the many ways drugs are moved into, around, and out of the body, and how drug molecules are changed in the process. Pharmacokinetics includes absorption, distribution, metabolism, and excretion. Pharmacokinetics may be altered by renal or hepatic impairment, body size, genetic polymorphism, or interactions with food or other drugs. Pharmacodymaics is concerned with how drugs cause an effect in the body, having reached the site of action. Drugs may act as a receptor agonist, antagonist, or partial agonist. Each drug’s unique pharmacokinetic and pharmacodynamic properties guide the selection of the right drug, dose, rate or frequency, and route of adminsitration for a given patient.
Comparative Pharmacodynamics of Inhaled Anesthetics
Authors: Parker Nicholas M.
Published: May 2024

A variety of effective inhaled anesthetics is available, including nitrous oxide, sevoflurane, isoflurane, desflurane, enflurane, and halothane. The agents differ in time to onset, hemodynamic effects, pungency, and toxicities. Nitrous oxide has an excellent safety profile but cannot produce complete anesthesia on its own. Sevoflurane may be used for induction and maintenance of anesthesia but can cause hypotension. Isoflurane is potent and inexpensive, which may be of benefit for long operations. Desflurane is useful for rapidly increasing the depth of anesthesia during painful parts of a surgery. Understanding the pharmacologic similarities and differences of each inhaled anesthetic allows for optimal anesthetic selection for a given patient and operation.
Substance Use Disorder
Authors: Yu Raymond C. , Conermann Till
Published: May 2024

This chapter reviews key concepts and definitions pertaining to substance abuse, addiction, and dependence, as well as important preoperative, intraoperative, and postoperative considerations when managing these patients. Abused and addictive substances exert their reinforcing effects through the activation of the mesolimbic dopamine system in the central nervous system (CNS). Genetic and epigenetic variations account for variable responses to addictive substances. Preoperatively, patients may present with altered mental status, and identification of ingested substance is helpful for intraoperative management. In addition to physiologic derangements, acute intoxication of addictive substances will lower minimum alveolar concentration (MAC), with exceptions such as cocaine and CNS stimulants, which do the contrary. Chronic substance abuse will typically increase MAC requirements. Postoperatively, patients might require intensive care monitoring for withdrawal symptoms and stabilization. Different medications (e.g., naltrexone, buprenorphine, methadone) are being utilized by physicians to help treat substance use disorder (SUD), and these medications may complicate anesthetic management in these patients. This chapter discusses important anesthetic considerations in patients abusing several common drugs of abuse: alcohol, opioids, cocaine, LSD, barbiturates, amphetamine, PCP, and marijuana.
Epidural and Intrathecal Anesthetics
Authors: Medina Wilson Alfredo , Gershon Laura Liss
Published: May 2024

This chapter explores the clinical implications of neuraxial anesthesia in review. Neuraxial content discussed includes epidural, spinal, and caudal anesthesia. Specific focus on indications, contraindications, sites of pharmacologic action, as well as factors affecting onset, duration, termination of action, and level of blockade, are addressed. The physiologic impact of neuraxial anesthesia, in addition to complications such as local anesthetic systemic toxicity, is also discussed. The intent of this chapter is to provide a resource for clear and concise rapid board review preparation.
Barbiturates
Authors: Ferguson Kris , Soin Amol
Published: May 2024

Thiopental is the prototypical barbiturate intravenous induction agent. It has a rapid onset of action and quick termination of action. Termination of action is due to redistribution. It lacks analgesic properties, therefore airway manipulation can precipitate laryngospasm. Barbiturates have minimal impact on blood pressure and cardiac output; however, in patients with hypovolemia or shock, barbiturates can precipitate significant hypotension due to a decrease in sympathetic outflow. Barbiturates are contraindicated in patients with acute intermittent porphyria.
Benzodiazepines
Authors: Ferguson Kris , Papapetrou Peter
Published: May 2024

Benzodiazepines are a class of drugs often used for anxiolysis and sedation. Benzodiazepines are also used in an outpatient setting for anxiety, panic disorder, alcohol withdrawl, insomnia, seizures and it also has muscle relaxant properties. The benzodiazepine binds to the gama-aminobutyric acid receptor A (GABA A) prolonging the opening of the chloride channel thereby hyperpolarizing the cell. Benzodiazepines quickly cross the blood brain barrier producing sedation. There is minimal impact on the cardiovascular system. When used in isolation, there is a modest respiratory depression. When benzodiazepines are combined with opioids there is a synergistic effect which can significantly depress respiratory drive. Higher doses of benzodiazepines may also cause anterograde amnesia. Flumazenil is the benzodiazepine reversal agent.
Local Anesthetics
Authors: Papapetrou Peter , Ferguson Kris
Published: May 2024

Local anesthetics are especially useful agents used in the perioperative setting to prevent and control acute pain. They act by binding to voltage-gated sodium channels and terminate propagation of nerve action potentials. They are categorized as either ester or amides based on their chemical structure, which are also metabolized differently and carry different allergic potential. Ester local anesthetics carry higher allergic potential due to their metabolite PABA. Potency of local anesthetics is related to their lipid solubility, and onset is determined by pKa. Side effects from local anesthetics can occur, which include transient neurologic symptoms (TNS), cauda equina syndrome, and methemoglobinemia. Local anesthetic toxicity can be manifested as minor changes such as tinnitus or restlessness but can progress to seizures and circulatory collapse. Local anesthetic toxicity is treated with supportive measures as well as 20% lipid emulsion.
Malignancy
Authors: Gluncic Vicko
Published: May 2024

Approximately 40% of people have a chance to develop cancer during their lifetime, and two-thirds of these patients will undergo anesthesia and surgery. In perioperative care, special consideration should be paid to the patients receiving chemotherapy and/or radiation and/or immunotherapy due to side effects affecting different organ systems. In addition, paraneoplastic syndromes may accompany cancers and cause pathophysiologic disturbances. Anesthesia, surgery, and perioperative analgesia also have immunomodulatory effects and cause stress reaction—both of which can possibly contribute to metastatic dissemination of malignant cells and subsequent cancer progression. Studies showed that anesthetic techniques could affect many of these pathophysiological processes—influencing risk of cancer recurrence in either a beneficial or harmful way. Currently there are insufficient clinical data to support that specific anesthetic interventions have more favorable outcomes. However, retrospective clinical studies have indicated an association between regional anesthetic techniques for primary cancer surgery and reduced incidence of metastatic disease. Nevertheless, the emphasis should be adequate pain control, as there is significant evidence that pain-related stress reaction mediated via β-adrenergic activation promotes neoplastic propagation and metastasis, thus decreasing survival rates. Optimal perioperative patient care requires individual assessment of the impact of cancer and its treatment on the functional reserve of all major organ systems. While further research of the anesthetic techniques and drugs that could minimize the perioperative inflammation and pain is important, close cooperation of anesthesiologists with oncologists and surgeons ensures optimal treatment.
Endobronchial Intubation
Authors: Kassem Hisham , Viswanath Omar
Published: May 2024

Endobronchial intubation (EI) is the placement of an endotracheal tube in either the right or left mainstem bronchus. This can be done both intentionally and inadvertently. In the perioperative period, EI is typically used to assist in surgical exposure during certain thoracic and cardiac surgery. EI can be achieved with multiple devices, such as double-lumen tubes and bronchial blockers, providing lung isolation. The understanding of the physiological changes associated with EI and the management of hypoxia is essential to the anesthesiologist. The familiarity with all the devices that can be used to secure EI is necessary to provide a safe perioperative environment for the patient to ensure the best outcomes.
Intravenous Fluid Therapy During Anesthesia
Authors: Guz David , McNamara Connor
Published: May 2024

Intravenous fluid therapy has been an essential element in the realms of medicine, particularly anesthesia and critical care, since its introduction in the early 1800s as a treatment for dehydration associated with cholera. Intravenous (IV) fluids serve to directly restore intravascular volume and subsequently, depending on the solution administered, variably redistribute throughout the body’s intra- and extra-cellular compartments. Intravenous fluid solutions have been listed as essential drugs by the World Health Organization and, like any other drug, improper use can be associated with adverse patient outcomes, including volume overload, acid/base disturbances, and surgical morbidity. Despite having been used for over 150 years, there remains no set strategy to dictate the appropriate volume and composition of IV fluids to be administered for a given clinical situation. While traditionally rigid weight-based formulae were used to approximate fluid deficits, the development of ERAS and sepsis protocols seek to individualize administration of fluids to a patients’ specific needs, utilizing modern methods including ultrasound and cardiac output monitoring. As part of the American Board of Anesthesiology BASIC exam curriculum, trainees are expected to have familiarity with the physiology of free water and electrolyte balance, the various classes and types of solutions commonly available, and commonly used paradigms for fluid administration.
Indications and Contraindications
Authors: Kremen Elizabeth , Keshavarzi Sahel
Published: May 2024

Increasing volumes of pediatric surgeries are being performed in outpatient ambulatory surgery settings. However, for the procedure to be appropriate in an outpatient setting, the patient must be reasonably healthy, the surgery must be straightforward and have minimal expected complications. The facility needs to be equipped to handle the high volume of patients, including screening patients and following up with patients and families postoperatively. The site needs to have a plan in place for emergencies and for unexpected need for escalation of care. Special considerations for case rescheduling include the acutely ill child, new onset upper respiratory infections, or children with obstructive sleep apnea.
Neurological Complications
Authors: Youssef Yasser M. A. , Ragheb-Mueller Nawal E.
Published: May 2024

This chapter reviews the neurological complications that may arise in anesthesia practice. Peripheral nerve injuries are rare but devastating complications that may occur in any patient undergoing surgical procedures. Most of these injuries are related to malpositioning of patients under general anesthesia; a significant proportion, however, are reported to occur following monitored anesthesia care (MAC) and regional anesthesia. The natural course of the perioperative neuropathy is variable and differs according to the mechanism of injury. Axonal degeneration and discontinuity carry the worst prognosis, with subsequent long-term disability. Given the potential for significant long-term complications for patients who sustain these injuries, anesthetists should maintain a high degree of vigilance to reduce risk and ensure proper positioning and adequate padding of surgical patients. Ultrasound-guided regional anesthesia has proven to be a superior tool to increase the success rate of nerve blocks; the literature, however, lacks any strong clinical evidence that it reduces the incidence of peripheral neuropathy.
Hypothermia
Authors: Sarrafpour Syena
Published: May 2024

Hypothermia, defined by a core temperature less than 35°C, is commonly seen during anesthesia. General anesthesia results in redistribution of warmer core blood (2°–4°C warmer) to the periphery, resulting in the majority of heat loss through radiation. The next common modes of heat loss are evaporation, followed by conduction and convection. As time under anesthesia continues for several hours, equilibrium is achieved with heat lost being equivalent to heat produced. Common anesthetics, such as volatile anesthetics and propofol, also hinder the body’s response to thermoregulation. Regional anesthesia also results in hypothermia, despite the warmer sensation of the skin anesthetized. Preoperative warming of a patient for approximately 30 minutes with forced air systems is the most effective way to prevent heat loss. Even mild hypothermia can result in increased oxygen requirements due to shivering, increased catecholamines, and increased myocardial adverse events. Furthermore, there are increased rates of immune dysfunction, coagulopathy, perioperative blood loss and transfusion needs, post-anesthesia care unit (PACU) stays, and costs.
Aspiration of Gastric Contents
Authors: Sarwary Mariam , Schulman Nathan
Published: May 2024

The administration of anesthesia places patients at risk for aspiration of gastric contents for several reasons, including decreased protective airway reflexes and relaxation of the lower esophageal sphincter. This chapter discusses preoperative and intraoperative measures to reduce the risk of aspiration, and gives a brief overview of the range of presentations, including transient pneumonitis and pneumonia. It also discusses treatment for witnessed or suspected aspiration, which is dependent on content and quality of material aspirated, with recent studies showing little benefit in prophylactic antibiotics or steroids.
Tricyclic Antidepressants
Authors: Munoz-Acuna Ronny , Munoz-Acuna Ricardo
Published: May 2024

Antidepressants are commonly prescribed medications generally used to treat depression, chronic pain, and some forms of acute pain. Tricyclic antidepressants (TCAs) block the reuptake of noradrenaline and serotonin in presynaptic terminals, which leads to increased concentration of these neurotransmitters in the synaptic cleft. TCAs also block muscarinic, histaminergic, and alpha adrenoceptors, potentially causing a broad spectrum of adverse effects. They can interact with other medications given in the perioperative period. The most common side effects involve the cardiovascular and central nervous systems. The anesthesiologist needs to be aware of the mechanism of action, potential side effects, and perioperative considerations to avoid potentially harmful complications. Early and accurate detection of harmful events is necessary. And supportive treatment is usually the treatment of choice.
Pathophysiology of Ischemia/Hypoxia
Authors: Latimer Dustin , Kaye Alan D.
Published: May 2024

Brain physiology can be compromised by a variety of mechanisms. This chapter describes physiologic and pathophysiologic states, including ischemic injury mechanisms and manifestations. Appropriate assessment, drugs, and techniques which optimize cerebral flow can maximize outcomes of patients with cerebral pathophysiology or limited reserve. This chapter will discuss the basic physiology of cerebral blood flow as well as hypoxia, ischemia, and the pathophysiologic consequence of abnormal substrate. Abnormalities of neurologic function are difficult to assess when a patient in undergoing surgery requiring general anesthesia, but we will also discuss monitoring parameters to potentially prevent neurologic complications associated with surgery.
Neuromuscular Transmission
Authors: Mundi Gurpreet , Roberman Dmitry
Published: May 2024

The simplest neuromuscular transmission involves motor neurons in the spinal cord that synapse with muscle fibers at the motor end plate. Transmission across the length of a neuron involves the use of an action potential, which can be defined as the sudden rise and subsequent fall in membrane potential that propagates down the length of a neuronal axon. The transmission of a signal across a synapse is chemical in nature, involving a neurotransmitter and receptors. Many anesthetic drugs interact with these components; thus understanding the physiology of neuromuscular transmission is critical to the practice of anesthesiology.
Ganglionic Transmission
Authors: Strand Natalie H. , Maloney Jillian A.
Published: May 2024

The autonomic nervous system is divided into the sympathetic and parasympathetic nervous systems. The preganglionic and postganglionic neurons synapse in the autonomic ganglia. All preganglionic neurons release acetylcholine, and the action of acetylcholine is terminated by reuptake or degradation by acetylcholinesterase. Presynaptic voltage gated calcium channels are involved in the release of acetylcholine into the synaptic cleft. Postsynaptic ligand gated sodium channels are involved in the propagation of neuronal signals in response to acetylcholine binding. Norepinephrine is released by most postganglionic neurons of the sympathetic nervous system, and the action of norepinephrine is terminated by reuptake or degradation by degradation catechol-o-methyl transferase (COMT). Patients with autonomic neuropathy have several important clinical implications for the anesthesiologist.
Temperature Sensing, Heat Production, and Conservation
Authors: Guruswamy Jayakar , Epelman Matthew
Published: May 2024

The physiologic changes in response to temperature sensing, heat production, and conservation produced by the body are complex and require an understanding of certain molecular and cellular pathways. Although seemingly immediate reactions are observed, temperature regulatory pathways involve several steps in both the peripheral and central nervous system that indeed have clinical relevance. An awake individual will often produce predictable behaviors in response to temperature fluctuations; however, this is not applicable to the anesthetized patient. It is therefore the responsibility of the anesthesiologist to anticipate temperature derangements and act appropriately to correct them. The hypothalamus maintains temperature within a relatively narrow range, and thus any deviations from normal temperature require prompt intervention. A complex web of receptor modifications, signaling pathways, sensory integration, and behaviors results in finely tuned temperature adaptability in the awake and anesthetized human.
Cerebral Cortex
Authors: Shah Rutvij
Published: May 2024

The cerebral cortex constitutes about 83% of total brain tissue. The cortex has two hemispheres (left and right) and both the hemispheres are connected via corpus callosum. Both the hemispheres have four lobes (frontal, parietal, temporal, and occipital). The cerebral cortex constitutes the highest control areas for memory, attention, vision, language, motor control, and sensory perception. Microscopically, the cerebral cortex has six layers. The cerebral cortex plays an important role in consciousness. Anesthetic agents generate unconsciousness via breaking the communication of the posterior parietal area, posterior cingulate cortex, and precuneus.
Respiratory Centers
Authors: Murguia-Fuentes Ricardo , Kaye Alan D.
Published: May 2024

Respiration, specifically ventilation, is a predominantly involuntary vital function required for energy production and metabolism for survival. The nervous system is able to control and regulate the automatic features of this function through a diffuse group of neurons in the brainstem known as the respiratory center, which is composed of the pneumotaxic center, a dorsal and a ventral respiratory group of neurons. Located in the medulla, the dorsal group mainly stimulates inspiration and the generation of the respiratory rhythm; the ventral group has both inspiratory and expiratory functions, and it contains the pre-Bötzinger complex, which has also been proven to have a role in the respiratory rhythm due to its pacemaker firing pattern; the pneumotaxic center primarily works as an inhibitor of the inspiratory process, shortening its cycle and increasing respiratory rate. The neural mechanisms to achieve this control include the central drive, the afferences of central and peripheral chemoreceptors; the latter sends signaling through branches of the glossopharyngeal and vagal nerves from the carotid and aortic bodies, respectively, to the respiratory center. In terms of chemical stimuli, oxygen and carbon dioxide have direct effect over the chemosensitive area of the brainstem, while oxygen acts indirectly by the stimuli of the peripheral chemoreceptors.
Nociception
Authors: Lennertz Richard
Published: May 2024

Pain can be defined as an unpleasant sensory and emotional experience associated with, or resembling that associated with, actual or potential tissue damage. Nociception is the process of perceiving pain. Specialized nerve fibers called nociceptors convey noxious stimuli to the spinal cord, where their signals are integrated and passed on to the brain. Injury enhances the perception of pain. Nociceptor sensitization and central sensitization lead to hyperalgesia and allodynia. These changes are discussed in the context of inflammatory pain and neuropathic pain, common types of injury-related pain. Autonomic contributions to pain are also discussed in the context of complex regional pain syndrome.
Lung Functions, Cellular Processes, and Surfactant
Authors: Nathani Harsh , Joseph Antony
Published: May 2024

The lungs are the primary organs of the respiratory system and have multiple physiological functions—gas exchange, immunity, homeostasis, and metabolism. The lungs consist of multiple cell lines, with unique functions, that aid in performing the physiological functions of the respiratory system. Surfactant is an important substance produced by type 2 pneumocytes that helps reduce surface tension within the alveoli.
Oxygen Transport
Authors: Chang Michael , Knox Nigel
Published: May 2024

Oxygen is an essential component of life, contributing to aerobic respiration by acting as the terminal electron acceptor in the ATP-generating electron transport chain in the mitochondria at the cellular level. As such, it is easily overlooked as the most common drug administered during anesthesia and critical care medicine. Oxygen transport can be described as convective or diffusive, the latter distinguished from the former as a passive process. The main carrier of oxygen during transport in the systemic circulation is hemoglobin, to which 98% of oxygen is bound. The affinity of oxygen to these hemoglobin carriers is crucial to its delivery to the tissue beds. This chapter focuses on the transport and delivery of oxygen, and physiological effects on this process.
Systemic Effects of Hypocarbia and Hypercarbia
Authors: Smith Sarah C.
Published: May 2024

The normal PaCO2 level in an adult is 38–42 mmHg, but physiologic adaptations to certain stimuli, pathologic processes, or even iatrogenic interventions may result in deviations from this normal range. The resulting hypo- or hypercarbia may have a variety of effects on different organ systems, and the nature and magnitude of these effects is dictated by whether the change in PaCO2 is acute or chronic. The perioperative period is often accompanied by alterations in PaCO2 due to the respiratory effects of anesthetics and analgesics or the deliberate or inadvertent induction of hyper- or hypocarbia by the anesthesiologist. Alternatively, patients may present for surgery in disease states resulting in perturbations in PaCO2, or may develop hypercarbia as a result of the insufflation of CO2 for facilitation of a procedure, such as laparoscopic surgery or endoscopy. The anesthesiologist must be aware of the systemic effects of hyper- and hypocarbia so that these alterations in physiology can either be managed or deliberately exploited for therapeutic effect.
Basic Interpretation of Arterial Blood Gas and Temperature Correction
Authors: Zanath Erica , Helou Mada
Published: May 2024

Acid-base balance is important physiologically as biochemical reactions are dependent upon normal pH. Normal physiologic pH is 7.4. A blood pH <7.35 is acidemia, whereas a blood pH >7.45 is alkalemia. According to the Henderson-Hasselbalch equation, pH is directly proportional to changes in bicarbonate ion concentration and indirectly proportional to changes in PaCO2. A primary disturbance in PaCO2 is respiratory disorder, whereas a primary disturbance in bicarbonate ion concentration is a metabolic disorder. Buffers and both respiratory and renal alterations compensate for changes in acid-base balance. Blood gas analysis should proceed in a systematic manner: (1) evaluate pH—acidemia vs. alkalemia; (2) determine if the primary disturbance is respiratory or metabolic; (3) determine if compensation is present; (4) evaluate chronicity.
Respiratory Centers
Authors: Cornwell Drew , Kohan Lynn
Published: May 2024

Discussion in this chapter reviews high-yield details of neural control of ventilation as generated by the respiratory center. Primary control is generated in the brainstem, specifically the medulla and pons. Within the medulla exist two groups referred to by their positioning: the dorsal respiratory group (DRG) and ventral respiratory group (VRG). The DRG is associated with control of inspiration, while the VRG is associated with expiration. Pontine control of respiratory rhythm is well demonstrated in animal studies, but less effectively demonstrated in humans. Cortical input and control play a lesser role, but is obvious as demonstrated by the ability to intentionally hyper/hypoventilate oneself, as well as the limbic and hypothalamic response during emotional states.
Central and Peripheral Chemoreceptors
Authors: Cornwell Drew , Kohan Lynn
Published: May 2024

This chapter will present a brief overview of the central and peripheral chemoreceptors discusses their important role in afferent signaling for the control of ventilation. Chemoreceptors respond to changes in carbon dioxide, pH, and oxygen to augment ventilation in order to maintain homeostasis. Central receptors of the brain within the CSF respond primarily to changes in arterial carbon dioxide levels. A number of peripheral receptors exist in various locations (carotid body, aortic arch, and parenchyma of the lungs) and react to altered arterial oxygen and hydrogen concentrations. The chapter also discusses the anesthetic considerations of chemoreceptors in relation to preoperative and intraoperative periods.
Respiratory and Congenital Pediatric Airway Problems
Authors: Al-Haddadin Caroline , Harb Alain
Published: May 2024

Pediatric airway disorders may be congenital (anatomical) or acquired (infectious), with obstruction being a common feature. These congenital syndromes are very challenging, and some are common: Hurler, Pierre Robin, Treacher Collins, Goldenhar, and Crouzon syndromes, and cleft lip and palate. Clinical presentation and consequences of airway obstruction vary by age. The perioperative care of these patients involves input from many specialists. The benefit of the surgical procedure should be balanced against the risk of exposing the child to general anesthesia. Anesthesia should ideally be given by experienced anesthesiologists in handling pediatric airway problems and resuscitation, and in a center in which pediatric intensive care facilities are available. Some patients may present with an isolated airway abnormality, while others present with associated anomalies or syndromes. A comprehensive preoperative assessment is crucial for the preparation and management of anesthesia. Patients with mild airway obstruction can usually be managed conservatively with nasopharyngeal airways or prone positioning. Moderate or severe obstruction requires more invasive interventions such as laryngeal mask airway (LMA), video laryngoscopy, fiberoptic intubation, or tracheostomy. Awake intubation often cannot be used in children because of inadequate cooperation. In addition, children have higher rates of oxygen consumption, significantly shortening the period of apnea that can be safely tolerated. Patients should be extubated when fully awake, with close observation for signs of airway obstruction. Adequate analgesia is an important part of the balanced anesthetic technique.
Vocal Cords
Authors: Moore Warner , Kaye Alan D.
Published: May 2024

The vocal cords, located in the larynx, serve three vital purposes: protection from choking, vibration in order to produce sound, and regulation of airflow into the lungs. Depending on age and gender, approaches to treating the underlying problem in the vocal cords may vary. Some of the most common clinical diagnoses involving the vocal cords include laryngitis (usually bacterial or viral infection), laryngeal papillomatosis, and vocal cord paralysis. Many specialized techniques may be used to assess the severity of damage to the vocal cords, including videostroboscopy and laryngeal electromyography. For anesthetic management, pre- and postoperative risk factors should always be evaluated and minimized. Depending on the severity of the surgery, local anesthesia, light sedation, and general anesthesia are all options indicated for use. After surgery, continuous positive airway pressure (CPAP) and heliox can improve complications of stridor until the patient fully recovers from anesthesia.
Steroids
Authors: Maheshwari Neeraj , Manders Larry
Published: May 2024

Corticosteroids are well known for their anti-inflammatory and immunosuppressive effects. It is no surprise that the diverse functions of steroids have allowed them to be used in equally diverse disease states, including autoimmune, rheumatologic, infectious, inflammatory, and neoplastic processes. The regimented use of corticosteroids have been well established in pathologies involving reactive airway disease; however, there are no clear guidelines regarding the use of this class of medications in the perioperative and critical care settings. This outlines the anti-inflammatory properties of systemic and inhaled corticosteroids used to treat and manage various pulmonary diseases, including bronchial asthma and chronic obstructive pulmonary disease (COPD).
Ventricular Function
Authors: Yousef John , Manders Larry
Published: May 2024

The heart consists of four chambers: two atrias and two ventricles. The right ventricle is a low-pressure system which pumps the blood incoming from the body and into the lungs. The left ventricle is a high-pressure system that pumps oxygenated blood from the lungs and into the body. Each side of the heart has its own pressure gradients, muscle composition, blood supply, and anatomical differences. This chapter briefly discusses the anatomical composition of the heart with preference paid toward the ventricles, which are the drivers of output for each respective side of the heart.
Force, Velocity, Length, Rate of Shortening
Authors: Daklallah Youssef , Manders Larry
Published: May 2024

Understanding cardiac performance is dependent on understanding myocardial contractility and inotropy. The concept of inotropy is multifaceted. It is defined as the force of a cardiac muscle’s contraction. Inotropy can be affected by multiple variables and disease processes that are relevant to any patient receiving an anesthetic. In this chapter, the authors define and discuss the relationships between the force of contraction, sarcomere length, velocity, and the rate of shortening.
Myocardial Oxygen Utilization/Consumption
Authors: Tobes Daniel , Manders Larry
Published: May 2024

Myocardial O2 supply and demand exist at all times in a fragile balance. Situations where demand exceeds supply lead to myocardial ischemia. The heart has a relatively high O2 consumption (MVO2) compared with other organs due to its workload. MVO2 can vary greatly based on the current workload of the heart; MVO2 during heavy exercise exceeds that of any other organ in the body. This chapter will summarize myocardial oxygen utilization and consumptions as it relates to ability pump blood and transport oxygen to the rest of our body.
Cardiac Output
Authors: Sohn Jacqueline , Pesa Nicholas
Published: May 2024

Cardiac output (CO) is defined as a volume of blood ejected by the heart per unit of time. This chapter discusses the four factors that affect cardiac output: heart rate, myocardial contractility, preload, and afterload. Furthermore, it also discusses the physiological background of Fick’s principle and its use to calculate the cardiac output using physiological markers such as oxygen content and oxygen consumption.
Blood Volume and Distribution
Authors: Al-Attar Neal , Manders Larry
Published: May 2024

Approximately 60% of a person’s body weight is water. This can be further categorized and stated as 40% of one’s body weight is intracellular fluid, 15% is interstitial fluid, and 5% is intravascular fluid. Maintenance of the intravascular volume is critical for adequate organ perfusion and function. This chapter briefly discusses the blood volume and distribution. The chapter highlights changes with age and sex, as well as predicting allowable changes and organ distribution during homeostasis.
Systolic, Diastolic, Mean, and Perfusion Pressures
Authors: Zanath Erica , Helou Mada
Published: May 2024

Blood pressure is generally reported as three components: a systolic pressure, diastolic pressure, and mean pressure. The systolic blood pressure is the highest pressure within the arterial vasculature. The diastolic blood pressure is the lowest pressure within the arterial vasculature reflective of the resting vessel tone. Mean arterial blood pressure is the average pressure in the vasculature. In addition to these aforementioned components, there are other important terms to understand with response to blood pressure and its effect on organ perfusion. Pulse pressure is the difference between systolic and diastolic pressure. Perfusion pressure represents the blood pressure driving blood flow to a specified organ.
Viscosity and Rheology
Authors: Padilla David , Sharma Archit
Published: May 2024

Blood viscosity and its behaviors under various degrees of shear stress (rheology) plays an important role in clinical situations of importance to the anesthesiologist. This chapter discusses examples of these various phenomenon, such as the overall transport of oxygen in the circulatory system, the determination of total peripheral resistance, the pathogenesis of deep-vein thrombosis, and tissue perfusion during open-heart surgery. A sound knowledge of rheological principles is thus an important requirement for optimal patient care, and the anesthesia provider can manipulate these to provide the best care to the patient.
Basics of Cardiopulmonary Resuscitation
Authors: Laborde Donnie
Published: May 2024

Cardiac arrest remains one of the leading causes of death. Thanks to the work and research of the American Heart Association, the survival rate has continued to improve over the last several years. Early recognition of cardiac arrest and high-quality basic life support (BLS) is vital for the return of spontaneous circulation (ROSC). BLS encompasses the following elements: assessment, airway conservation, ventilation (i.e., rescue breathing), and chest compression. The overarching goal of BLS is to provide oxygen, ventilation, and blood circulation. This is necessary to sustain cellular life until ROSC, or a secondary assessment, can be obtained to determine the problem, or reverse the underlying cause of cardiac arrest. If a patient appears unconscious, and the scene is safe to enter, the BLS assessment should begin immediately. The chapter includes a few of the American Heart Association Guideline Updates necessary for high quality cardiopulmonary resuscitation.
Angiotensin-Converting Enzyme Inhibitors and Angiotensin Receptor Blockers
Authors: Ohia Laurence , Guzman Jacob
Published: May 2024

The renin-angiotensin-aldosterone system inhibitors such as the ACEIs and ARBs are well established as therapies for managing as well as reducing morbidity due to hypertension, congestive heart failure, coronary artery disease, and diabetic retinopathy. This chapter aims to present and review the pharmacokinetics, discuss the clinical indications of ACEIs and ARBs with some literature review, explore the various adverse effects and medications that can be used to treat some of the adverse effects, and indicate contraindications to using these medications. Anesthetic considerations with regard to continuing ACEIs in the perioperative period and frequency of intraoperative hypotension, as well as recommendations regarding withholding ACEIs and ARBs in the preoperative period, also are presented.
Hepatic Function and Metabolism
Authors: Mahmood Faraz , Hackl Florian
Published: May 2024

The liver plays a vital role in human metabolism. Synthetic functions of the liver include synthesis of heme, albumin, and coagulation factors. Albumin significantly contributes to plasma oncotic pressure, as well as binding to exogenous drugs, providing immunomodulation, and antioxidant effects. The coagulation system is maintained with a balance between anti-thrombotic and pro-thrombotic processes. The liver is involved in synthesis of most pro- and anti-coagulant factors and liver injury can severely impair these processes and result in impaired coagulation, qualitatively or quantitatively altered platelets, or even disseminated intravascular coagulation (DIC). Moreover, the liver is essential for the metabolism of protein, carbohydrates, fat, and drugs. Hepatocellular insult or injury can result in altered drug metabolism or their availability in the body.
Anatomy of the Gastrointestinal and Hepatic Systems
Authors: Flanagan Timothy F. , Hackl Florian
Published: May 2024

The GI tract transports and absorbs water, electrolytes, and nutrients. Passage of materials is facilitated by peristaltic contractions of a smooth muscle layer and regulated by muscle sphincters. Liver anatomy, physiology, and pathophysiology are closely linked to the GI tract. Besides metabolic and synthetic functions, the liver is responsible for the production and secretion of bile into the duodenum via the common bile duct, facilitating fat absorption. The normal physiology, motility, and secretory activity of the GI tract can be altered by anesthetic drugs, and sympathetic and parasympathetic stimulation. Cirrhosis and end-stage liver disease are associated with portal hypertension, resulting in formation of varices along the GI tract. Anesthetic management in patients with diseases of the GI tract and end-stage liver disease is challenging and requires an understanding of the normal liver and GI anatomy. This chapter describes the basics of liver and GI anatomy, histology, and important pathophysiological processes.
Renal and Urinary Systems/Electrolyte Balance
Authors: Cieslinski Lindsey
Published: May 2024

The kidneys are essential organs for maintenance of homeostasis within the body. The functional unit of the kidney is the nephron. It is responsible for glomerular filtration, tubular reabsorption, and tubular secretion resulting in urine formation. Renal blood flow (RBF) is regulated via intrinsic and extrinsic autoregulatory mechanisms when the mean arterial pressure is normally maintained. The kidney is a major regulator of body water, and inorganic ions necessary to maintain electrolyte balance. It regulates body fluid osmolality and intravascular volume, eliminates metabolic waste products, and aids in regulation of pH via acid-base balance. Hormones essential to metabolic function are secreted by the kidneys. The chapter also highlights some perioperative considerations when the renal physiology is disrupted.
Dopaminergic Drugs
Authors: Sidagam Vasu
Published: May 2024

This chapter discusses dopaminergic drugs whose pharmacokinetic and pharmacodynamic properties are explained. Dopamine metabolism, inhibiting mechanisms, and enzymes are shown in a diagram. Ergotamine derived and non-ergot dopamine agonist drugs are described.
Alternatives to Blood Transfusion
Authors: Watt Stacey , Lamb Jennifer
Published: May 2024

This chapter will focus on alternatives to blood transfusion as a means to maintain patient hemodynamic stability in the field of anesthesiology. Topics will include a brief description of optimal transfusion practice and potential situations where avoiding blood transfusion may be appropriate or desirable. Preoperative patient optimization will be discussed, with a focus on correction of preexisting anemia, augmentation of innate hematopoiesis, and potential autologous blood donation prior to going to the operating room. Intraoperative strategies to be considered include methods for minimizing procedural blood loss, as well as accepted practices for managing intravascular volume derangements. Normovolemic hemodilution and autotransfusion after surgical blood salvage will be examined as intraoperative alternatives to allogenic blood transfusion.
Complications of Transfusions
Authors: Scott Courtney L. , Boydston Elaine A.
Published: May 2024

An understanding of the potential complications of blood transfusion is important in order to make informed decisions regarding the risks and benefits. Non-hemolytic transfusion reactions may include febrile, allergic, or anaphylactic responses. The resultant complications can range from symptomatically mild to fatal. Hemolytic transfusion reactions are one of the most feared transfusion reactions and result from an ABO or antibody incompatibility leading to hemolysis. These reactions may be acute or delayed, and if recognized early, are often non-fatal. Infectious complications have decreased over the last several decades as testing capabilities have improved, although these risks are still present. The most common cause of transfusion-related mortality is due to transfusion-related acute lung injury (TRALI), thought to be caused by donor antigens that activate recipient neutrophils. The result is an ARDS-like condition, and the treatment is supportive. Other transfusion complications are related to the blood volumes transfused, including citrate toxicity, hyperkalemia, acidemia, and hypothermia.
Anticoagulants, Antithrombotics, and Antiplatelet Drugs
Authors: Torres Patrick , Ghabra Hussam
Published: May 2024

The perioperative management of anticoagulants requires a very focused and dedicated approach, weighing both risks and benefits for each individual patient. Multidisciplinary team cooperation is required to estimate the individual patient risk of thrombosis versus the risk of bleeding, to determine the timing of interruption of anticoagulation, and to decide if bridging therapy is needed (for very high-risk patients). This chapter reviews the basics of hemostasis, the most commonly used antiplatelet agents and anticoagulants, including their mechanism of action, and a focused overview of perioperative management of anticoagulation. Table 310.1 summarizes the medications discussed in this chapter.
Adrenal Disease
Authors: Romanov Evgeney , Noguera Edward
Published: May 2024

Theadrenal glands are in the retroperitoneum in the medial aspect of the upperpole of each kidney. The fully matured adrenalgland is about 5cm by 3 cm and is 1 cm think. The right gland is pyramidal and the left is oval shaped. Anatomically, the adrenals have a cortex anda medulla. The medulla secretescatecholamines and, functionally, is part of the sympathetic nervoussystem.
Biochemistry of Normal Body Metabolism
Authors: Torres Felipe Vasconcelos , Rossi Raquel Montagner
Published: May 2024

This chapter discusses the highlights of normal body metabolism. The difference between catabolic and anabolic processes is explained. Anabolic reactions are synthetic and occur in postprandial states, while catabolic reactions are defined by breakdown and are predominant during fasting. There is a close interaction between organs and tissues in order to maintain a constant and adequate supply of nutrients, as well as to store energy for future use. Some organs will be more dependent on glucose, while others are more versatile and can use different molecules as fuel. The role of the liver as one of the major regulators of body metabolism for carbohydrates, lipids, and proteins is discussed. Finally, there is a brief discussion on cellular respiration and on the definition of respiratory quotient.