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General anaesthesia (UK) or general anesthesia (US) is a medically induced loss of
consciousness Consciousness, at its simplest, is sentience and awareness of internal and external existence. However, the lack of definitions has led to millennia of analyses, explanations and debates by philosophers, theologians, linguisticians, and scien ...
that renders the patient unarousable even with painful stimuli. This effect is achieved by administering either intravenous or inhalational general anaesthetic medications, which often act in combination with an analgesic and
neuromuscular blocking agent Neuromuscular-blocking drugs block neuromuscular transmission at the neuromuscular junction, causing paralysis of the affected skeletal muscles. This is accomplished via their action on the post-synaptic acetylcholine (Nm) receptors. In clin ...
. Spontaneous ventilation is often inadequate during the procedure and intervention is often necessary to protect the airway. General anaesthesia is generally performed in an
operating theater An operating theater (also known as an operating room (OR), operating suite, or operation suite) is a facility within a hospital where surgical operations are carried out in an aseptic environment. Historically, the term "operating theater" refe ...
to allow surgical procedures that would otherwise be intolerably painful for a patient, or in an
intensive care unit 220px, Intensive care unit An intensive care unit (ICU), also known as an intensive therapy unit or intensive treatment unit (ITU) or critical care unit (CCU), is a special department of a hospital or health care facility that provides intensi ...
or emergency department to facilitate endotracheal intubation and mechanical ventilation in critically ill patients. A variety of drugs may be administered, with the overall goal of achieving
unconsciousness Unconsciousness is a state in which a living individual exhibits a complete, or near-complete, inability to maintain an awareness of self and environment or to respond to any human or environmental stimulus. Unconsciousness may occur as the re ...
, amnesia,
analgesia Pain management is an aspect of medicine and health care involving relief of pain (pain relief, analgesia, pain control) in various dimensions, from acute and simple to chronic and challenging. Most physicians and other health professional ...
, loss of reflexes of the autonomic nervous system, and in some cases paralysis of skeletal muscles. The optimal combination of anesthetics for any given patient and procedure is typically selected by an
anaesthetist Anesthesiology, anaesthesiology, or anaesthesia is the medical specialty concerned with the total perioperative care of patients before, during and after surgery. It encompasses anesthesia, intensive care medicine, critical emergency medicine ...
, or another provider such as a nurse anaesthetist (depending on local practice and law), in consultation with the patient and the surgeon, dentist, or other practitioner performing the operative procedure.


History

Attempts at producing a state of general anaesthesia can be traced throughout recorded history in the writings of the ancient Sumerians, Babylonians,
Assyria Assyria ( Neo-Assyrian cuneiform: , romanized: ''māt Aššur''; syc, ܐܬܘܪ, ʾāthor) was a major ancient Mesopotamian civilization which existed as a city-state at times controlling regional territories in the indigenous lands of the ...
ns, Egyptians,
Greeks The Greeks or Hellenes (; el, Έλληνες, ''Éllines'' ) are an ethnic group and nation indigenous to the Eastern Mediterranean and the Black Sea regions, namely Greece, Cyprus, Albania, Italy, Turkey, Egypt, and, to a lesser extent, oth ...
,
Romans Roman or Romans most often refers to: *Rome, the capital city of Italy * Ancient Rome, Roman civilization from 8th century BC to 5th century AD *Roman people, the people of ancient Rome *''Epistle to the Romans'', shortened to ''Romans'', a lette ...
, Indians, and Chinese. During the
Middle Ages In the history of Europe, the Middle Ages or medieval period lasted approximately from the late 5th to the late 15th centuries, similar to the post-classical period of global history. It began with the fall of the Western Roman Empire ...
, scientists and other scholars made significant advances in the
Eastern world The Eastern world, also known as the East or historically the Orient, is an umbrella term for various cultures or social structures, nations and philosophical systems, which vary depending on the context. It most often includes at least ...
, while their European counterparts also made important advances. The
Renaissance The Renaissance ( , ) , from , with the same meanings. is a period in European history The history of Europe is traditionally divided into four time periods: prehistoric Europe (prior to about 800 BC), classical antiquity (800 BC to AD ...
saw significant advances in
anatomy Anatomy () is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having it ...
and surgical technique. However, despite all this progress, surgery remained a treatment of last resort. Largely because of the associated pain, many patients chose certain death rather than undergo surgery. Although there has been a great deal of debate as to who deserves the most credit for the discovery of general anaesthesia, several scientific discoveries in the late 18th and early 19th centuries were critical to the eventual introduction and development of modern anaesthetic techniques. Two enormous leaps occurred in the late 19th century, which together allowed the transition to modern surgery. An appreciation of the
germ theory of disease The germ theory of disease is the currently accepted scientific theory for many diseases. It states that microorganisms known as pathogens or "germs" can lead to disease. These small organisms, too small to be seen without magnification, invade ...
led rapidly to the development and application of
antiseptic An antiseptic (from Greek ἀντί ''anti'', "against" and σηπτικός ''sēptikos'', "putrefactive") is an antimicrobial substance or compound that is applied to living tissue/skin to reduce the possibility of infection, sepsis, or putre ...
techniques in surgery. Antisepsis, which soon gave way to
asepsis Asepsis is the state of being free from disease-causing micro-organisms (such as pathogenic bacteria, viruses, pathogenic fungi, and parasites). There are two categories of asepsis: medical and surgical. The modern day notion of asepsis is deri ...
, reduced the overall
morbidity A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not immediately due to any external injury. Diseases are often known to be medical conditions that a ...
and mortality of surgery to a far more acceptable rate than in previous eras. Concurrent with these developments were the significant advances in pharmacology and
physiology Physiology (; ) is the scientific study of functions and mechanisms in a living system. As a sub-discipline of biology, physiology focuses on how organisms, organ systems, individual organs, cells, and biomolecules carry out the chemical ...
which led to the development of general anaesthesia and the control of pain. On 14 November 1804, Hanaoka Seishū, a Japanese surgeon, became the first person on record to successfully perform surgery using general anaesthesia. In the 20th century, the safety and efficacy of general anaesthesia was improved by the routine use of
tracheal intubation Tracheal intubation, usually simply referred to as intubation, is the placement of a flexible plastic tube into the trachea (windpipe) to maintain an open airway or to serve as a conduit through which to administer certain drugs. It is frequentl ...
and other advanced airway management techniques. Significant advances in monitoring and new anaesthetic agents with improved pharmacokinetic and pharmacodynamic characteristics also contributed to this trend. Finally, standardized training programs for anaesthesiologists and nurse anaesthetists emerged during this period.


Purpose

General anaesthesia has many purposes and routinely used in almost all surgical procedures. An appropriate surgical anesthesia should include the following goals: # Hypnosis/Unconsciousness (loss of awareness) # Analgesia (loss of response to pain) # Amnesia (loss of memory) # Immobility (loss of motor reflexes) # Paralysis (skeletal muscle relaxation and normal muscle relaxation)


Biochemical mechanism of action

The biochemical mechanism of action of general anaesthetics is not well understood. Theories need to explain the function of anaesthesia in animals and plants. To induce unconsciousness, anaesthetics have myriad sites of action and affect the
central nervous system The central nervous system (CNS) is the part of the nervous system consisting primarily of the brain and spinal cord. The CNS is so named because the brain integrates the received information and coordinates and influences the activity of all p ...
(CNS) at multiple levels. General anaesthesia commonly interrupts or changes the functions of CNS components including the
cerebral cortex The cerebral cortex, also known as the cerebral mantle, is the outer layer of neural tissue of the cerebrum of the brain in humans and other mammals. The cerebral cortex mostly consists of the six-layered neocortex, with just 10% consistin ...
,
thalamus The thalamus (from Greek θάλαμος, "chamber") is a large mass of gray matter located in the dorsal part of the diencephalon (a division of the forebrain). Nerve fibers project out of the thalamus to the cerebral cortex in all directions, ...
, reticular activating system, and
spinal cord The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the sp ...
. Current theories on the anaesthetized state identify not only target sites in the CNS but also neural networks and arousal circuits linked with unconsciousness, and some anesthetics potentially able to activate specific sleep-active regions. Potential molecular pharmacologic targets of general anaesthetics are GABAA,and NMDA glutamate receptors. General anesthesia was hypothesized to either enhance the inhibitory transmission or reduce the excitatory transmission of neuro signaling. Most volatile anesthetic has been found to be a GABAA agonist, although the site of action on the receptor remains unknown.
Ketamine Ketamine is a dissociative anesthetic used medically for induction and maintenance of anesthesia. It is also used as a recreational drug. It is one of the safest anesthetics, as, in contrast with opiates, ether, and propofol, it suppresses ...
is a non-competitive
NMDA receptor antagonist NMDA receptor antagonists are a class of drugs that work to antagonize, or inhibit the action of, the ''N''-Methyl-D-aspartate receptor ( NMDAR). They are commonly used as anesthetics for animals and humans; the state of anesthesia they induce ...
. The chemical structure and properties of anesthetics suggest they could target the plasma membrane, yet the exact mechanism remained a mystery for over 100 years. A study from 2020 demonstrated that inhaled anesthetics ( chloroform and isoflurane) could disrupt phospholipase D2 localization to the lipid rafts and led to production of the signaling molecule
phosphatidic acid Phosphatidic acids are anionic phospholipids important to cell signaling and direct activation of lipid-gated ion channels. Hydrolysis of phosphatidic acid gives rise to one molecule each of glycerol and phosphoric acid and two molecules of fatty ac ...
(PA). Signaling molecules lead to a cascade of events and eventually activation TWIK-related K+ channels (TREK-1). PLDnull fruit flies were shown to resist anesthesia, the results established a membrane mediated target for inhaled anesthetics.


Preoperative evaluation

Prior to a planned procedure, the anesthesiologist reviews medical records or interviews the patient to obtain information regarding their medical history and determine their perioperative risk. Base on the interview, the anesthesiologist develops an anesthetic plan and determines the best combination of drugs and dosages for the procedure. Additional monitoring devices may be necessary to ensure a safe and effective procedure. Key factors in this evaluation are the patient's age, gender, body mass index, medical and surgical history, current medications, and fasting time. Thorough and accurate preoperative evaluation is crucial for the effective safety of the anesthetic plan. For example, a patient who consumes significant quantities of alcohol or
illicit drugs The prohibition of drugs through sumptuary legislation or religious law is a common means of attempting to prevent the recreational use of certain intoxicating substances. While some drugs are illegal to possess, many governments regulate t ...
could be undermedicated during the procedure if they fail to disclose this fact, and this could lead to anaesthesia awareness or intraoperative hypertension. Commonly used medications can also interact with anaesthetics, and failure to disclose such usage can increase the risk during the operation. Inaccurate timing of last meal can also increase the risk for aspiration of food, and lead to serious complications. An important aspect of pre-anaesthetic evaluation is an assessment of the patient's
airway The respiratory tract is the subdivision of the respiratory system involved with the process of respiration in mammals. The respiratory tract is lined with respiratory epithelium as respiratory mucosa. Air is breathed in through the nose to ...
, involving inspection of the mouth opening and visualisation of the soft tissues of the
pharynx The pharynx (plural: pharynges) is the part of the throat behind the mouth and nasal cavity, and above the oesophagus and trachea (the tubes going down to the stomach and the lungs). It is found in vertebrates and invertebrates, though its st ...
. The condition of teeth and location of dental crowns are checked, and neck flexibility and head extension are observed. The most commonly performed airway assessment is the Mallampati classification, which evaluates the airway base on the ability to view airway structures with the mouth open and the tongue protruding. Mallampati tests alone has limited accuracy, other evaluations are routinely performed addition to the Mallampati test includes mouth opening, thyromental distance, neck range of motion, and mandibular protrusion. In a patient with suspected distorted airway anatomy, endoscopy or ultrasound is sometimes used to evaluate the airway before planning for the airway management.


Premedication

Prior to administration of a general anaesthetic, the anaesthetist may administer one or more drugs that complement or improve the quality or safety of the anaesthetic. Premedication also often has mild sedative effective and reduce the amount of anaesthetic agent used during the case. One commonly used premedication is clonidine, an alpha-2 adrenergic agonist. It reduces postoperative shivering, postoperative nausea and vomiting, and emergence delirium. However, a randomized controlled trial from 2021 demonstrated that clonidine is less effective at providing anxiolysis and more sedative in children of preschool age. Oral clonidine can take up to 45 minutes to take full effect, The drawbacks of clonidine include
hypotension Hypotension is low blood pressure. Blood pressure is the force of blood pushing against the walls of the arteries as the heart pumps out blood. Blood pressure is indicated by two numbers, the systolic blood pressure (the top number) and the dia ...
and bradycardia, but can be advantageous in patient with hypertension and tachycardia. Another commonly used alpha-2 adrenergic agonist is Dexmedetomidine, it is commonly used for provide short term sedative effect (<24 hours).
Dexmedetomidine Dexmedetomidine, sold under the trade name Precedex among others, is a drug used in humans for sedation. Veterinarians use dexmedetomidine for similar purposes in treating cats, dogs, and horses. It is also used in humans to treat acute agitation ...
and certain
atypical antipsychotic The atypical antipsychotics (AAP), also known as second generation antipsychotics (SGAs) and serotonin–dopamine antagonists (SDAs), are a group of antipsychotic drugs (antipsychotic drugs in general are also known as major tranquilizers and ne ...
agents may be also used in uncooperative children. Benzodiazepines are another commonly used drug for premedication. The most commonly utilized benzodiazepine is
Midazolam Midazolam, sold under the brand name Versed among others, is a benzodiazepine medication used for anesthesia and procedural sedation, and to treat severe agitation. It works by inducing sleepiness, decreasing anxiety, and causing a loss of ...
, it is characterized by a rapid onset and short duration. Midazolam is effective in reducing preoperative anxiety, including
separation anxiety Separation anxiety disorder (SAD) is an anxiety disorder in which an individual experiences excessive anxiety regarding separation from home and/or from people to whom the individual has a strong emotional attachment (e.g., a parent, caregiver, ...
in children. It also provides a reduction of post operative nausea/vomiting, mild sedation, sympathicolysis, and anterograde amnesia. Melatonin has been found to be effective as an anaesthetic premedication in both adults and children because of its hypnotic,
anxiolytic An anxiolytic (; also antipanic or antianxiety agent) is a medication or other intervention that reduces anxiety. This effect is in contrast to anxiogenic agents which increase anxiety. Anxiolytic medications are used for the treatment of anxiet ...
, sedative, analgesic, and anticonvulsant properties. Recovery is more rapid after premedication with melatonin than with midazolam, and there is also a reduced incidence of post-operative agitation and delirium. Melatonin has been shown to have a similar effect in reducing perioperative anxiety in adult patients compared to benzodiazepine. Another example of anaesthetic premedication is the preoperative administration of beta adrenergic antagonists, which shown to reduce the burden of arrhythmias after cardiac surgery. However, evidence also has shown an association of increased adverse events with beta-blockers in non-cardiac surgery. Anaesthesiologists may administer one or more
antiemetic An antiemetic is a drug that is effective against vomiting and nausea. Antiemetics are typically used to treat motion sickness and the side effects of opioid analgesics, general anaesthetics, and chemotherapy directed against cancer. They m ...
agents such as
ondansetron Ondansetron, sold under the brand name Zofran among others, is a medication used to prevent nausea and vomiting caused by cancer chemotherapy, radiation therapy, or surgery. It is also effective for treating gastroenteritis. It can be given by ...
, droperidol, or
dexamethasone Dexamethasone is a glucocorticoid medication used to treat rheumatic problems, a number of skin diseases, severe allergies, asthma, chronic obstructive lung disease, croup, brain swelling, eye pain following eye surgery, superior vena ...
to prevent postoperative nausea and vomiting. NSAIDs are commonly used analgesic premedication agent, and often reduce need for
opioid Opioids are substances that act on opioid receptors to produce morphine-like effects. Medically they are primarily used for pain relief, including anesthesia. Other medical uses include suppression of diarrhea, replacement therapy for opioid use ...
s such as
fentanyl Fentanyl, also spelled fentanil, is a very potent synthetic opioid used as a pain medication. Together with other drugs, fentanyl is used for anesthesia. It is also used illicitly as a recreational drug, sometimes mixed with heroin, cocain ...
or
sufentanil Sufentanil, sold under the brand names Dsuvia and Sufenta, is a synthetic opioid analgesic drug approximately 5 to 10 times as potent as its parent drug, fentanyl, and 500 times as potent as morphine. Structurally, sufentanil differs from fen ...
. Also gastrokinetic agents such as
metoclopramide Metoclopramide is a medication used for stomach and esophageal problems. It is commonly used to treat and prevent nausea and vomiting, to help with emptying of the stomach in people with delayed stomach emptying, and to help with gastroesoph ...
, and
histamine antagonist Antihistamines are drugs which treat allergic rhinitis, common cold, influenza, and other allergies. Typically, people take antihistamines as an inexpensive, generic (not patented) drug that can be bought without a prescription and provides re ...
s such as famotidine. Non-pharmacologic preanaesthetic interventions include playing cognitive behavioral therapy, music therapy, aromatherapy, hypnosis
massage Massage is the manipulation of the body's soft tissues. Massage techniques are commonly applied with hands, fingers, elbows, knees, forearms, feet or a device. The purpose of massage is generally for the treatment of body stress or pain. In E ...
, pre-operative preparation video, and guided imagery relaxation therapy, etc. These techniques are particularly useful for children and patients with intellectual disabilities. Minimizing sensory stimulation or distraction by video games may help to reduce anxiety prior to or during induction of general anaesthesia. Larger high-quality studies are needed to confirm the most effective non-pharmacological approaches for reducing this type of anxiety. Parental presence during premedication and induction of anaesthesia has not been shown to reduce anxiety in children. It is suggested that parents who wish to attend should not be actively discouraged, and parents who prefer not to be present should not be actively encouraged to attend.


Stages of anaesthesia

Guedel's classification Guedel's classification is a means of assessing of depth of general anesthesia introduced by Arthur Ernest Guedel (1883-1956) in 1920. History Since general anesthesia first became widely used in late 1846, assessment of anesthetic depth was a p ...
, described by Arthur Ernest Guedel in 1937, describes four stages of anaesthesia. Despite newer anaesthetic agents and delivery techniques, which have led to more rapid onset of—and recovery from—anaesthesia (in some cases bypassing some of the stages entirely), the principles remain. ;Stage 1: Stage 1, also known as ''induction'', is the period between the administration of induction agents and loss of consciousness. During this stage, the patient progresses from analgesia without amnesia to analgesia with amnesia. Patients can carry on a conversation at this time, and may complain about visual disturbance. ;Stage 2: Stage 2, also known as the ''excitement or delirium stage'', is the period following loss of consciousness and marked by excited and delirious activity. During this stage, the patient's
respiration Respiration may refer to: Biology * Cellular respiration, the process in which nutrients are converted into useful energy in a cell ** Anaerobic respiration, cellular respiration without oxygen ** Maintenance respiration, the amount of cellul ...
and
heart rate Heart rate (or pulse rate) is the frequency of the heartbeat measured by the number of contractions (beats) of the heart per minute (bpm). The heart rate can vary according to the body's physical needs, including the need to absorb oxygen and excr ...
may become irregular. In addition, there may be uncontrolled movements, vomiting, suspension of breathing, and
pupillary dilation Pupillary response is a physiological response that varies the size of the pupil, via the optic and oculomotor cranial nerve. A constriction response ( miosis), is the narrowing of the pupil, which may be caused by scleral buckles or drugs such ...
. Because the combination of spastic movements, vomiting, and irregular respiration may compromise the patient's airway, rapidly acting drugs are used to minimize time in this stage and reach Stage 3 as fast as possible. ;Stage 3: In Stage 3, also known as ''surgical anaesthesia'', the skeletal muscles relax, vomiting stops. Respiratory depression and cessation of eye movements are the hallmarks of this stage. The patient is unconscious and ready for surgery. This stage is divided into four planes: :# The eyes roll, then become fixed; eyelid and swallow reflexes are lost. Still have regular spontaneous breathing; :# Corneal and laryngeal reflexes are lost; :# The pupillary light reflex is lost; and the process is marked by complete relaxation of abdominal and intercostal muscles. Ideal level of anesthesia for most surgeries. :# Full diaphragm paralysis and irregular shallow abdominal respiration occur. ;Stage 4: Stage 4, also known as ''overdose'', occurs when too much anaesthetic medication is given relative to the amount of surgical stimulation and the patient has severe brainstem or medullary depression, resulting in a cessation of respiration and potential cardiovascular collapse. This stage is lethal without cardiovascular and respiratory support.


Induction

General anaesthesia is usually induced in an
operating theatre An operating theater (also known as an operating room (OR), operating suite, or operation suite) is a facility within a hospital where surgical operations are carried out in an aseptic environment. Historically, the term "operating theater" refe ...
or in a dedicated anaesthetic room adjacent to the theatre. General anaesthesia may also be conducted in other locations, such as an
endoscopy An endoscopy is a procedure used in medicine to look inside the body. The endoscopy procedure uses an endoscope to examine the interior of a hollow organ or cavity of the body. Unlike many other medical imaging techniques, endoscopes are inse ...
suite,
intensive care unit 220px, Intensive care unit An intensive care unit (ICU), also known as an intensive therapy unit or intensive treatment unit (ITU) or critical care unit (CCU), is a special department of a hospital or health care facility that provides intensi ...
,
radiology Radiology ( ) is the medical discipline that uses medical imaging to diagnose diseases and guide their treatment, within the bodies of humans and other animals. It began with radiography (which is why its name has a root referring to radiat ...
or
cardiology Cardiology () is a branch of medicine that deals with disorders of the heart and the cardiovascular system. The field includes medical diagnosis and treatment of congenital heart defects, coronary artery disease, heart failure, valvular h ...
department, emergency department, ambulance, or at the site of a
disaster A disaster is a serious problem occurring over a short or long period of time that causes widespread human, material, economic or environmental loss which exceeds the ability of the affected community or society to cope using its own resources ...
where extrication of the patient may be impossible or impractical. Anaesthetic agents may be administered by various routes, including inhalation,
injection Injection or injected may refer to: Science and technology * Injective function, a mathematical function mapping distinct arguments to distinct values * Injection (medicine), insertion of liquid into the body with a syringe * Injection, in broadca ...
( intravenous,
intramuscular Intramuscular injection, often abbreviated IM, is the injection of a substance into a muscle. In medicine, it is one of several methods for parenteral administration of medications. Intramuscular injection may be preferred because muscles have ...
, or subcutaneous),
oral The word oral may refer to: Relating to the mouth * Relating to the mouth, the first portion of the alimentary canal that primarily receives food and liquid **Oral administration of medicines ** Oral examination (also known as an oral exam or or ...
, and
rectal The rectum is the final straight portion of the large intestine in humans and some other mammals, and the gut in others. The adult human rectum is about long, and begins at the rectosigmoid junction (the end of the sigmoid colon) at the le ...
. Once they enter the
circulatory system The blood circulatory system is a system of organs that includes the heart, blood vessels, and blood which is circulated throughout the entire body of a human or other vertebrate. It includes the cardiovascular system, or vascular system, tha ...
, the agents are transported to their biochemical sites of action in the central and autonomic nervous systems. Most general anaesthetics are induced either intravenously or by inhalation. Commonly used intravenous induction agents include propofol,
sodium thiopental Sodium thiopental, also known as Sodium Pentothal (a trademark of Abbott Laboratories), thiopental, thiopentone, or Trapanal (also a trademark), is a rapid-onset short-acting barbiturate general anesthetic. It is the thiobarbiturate analog of pe ...
, etomidate, methohexital, and
ketamine Ketamine is a dissociative anesthetic used medically for induction and maintenance of anesthesia. It is also used as a recreational drug. It is one of the safest anesthetics, as, in contrast with opiates, ether, and propofol, it suppresses ...
. Inhalational anaesthesia may be chosen when intravenous access is difficult to obtain (e.g., children), when difficulty maintaining the airway is anticipated, or when the patient prefers it. Sevoflurane is the most commonly used agent for inhalational induction, because it is less irritating to the tracheobronchial tree than other agents. As an example sequence of induction drugs: # Pre-oxygenation or denitrogenation to fill lungs with 100% oxygen to permit a longer period of apnea during intubation without affecting blood oxygen levels #
Fentanyl Fentanyl, also spelled fentanil, is a very potent synthetic opioid used as a pain medication. Together with other drugs, fentanyl is used for anesthesia. It is also used illicitly as a recreational drug, sometimes mixed with heroin, cocain ...
for systemic analgesia during intubation # Propofol for sedation for intubation # Switching from oxygen to a mixture of oxygen and
inhalational anesthetic An inhalational anesthetic is a chemical compound possessing general anesthetic properties that can be delivered via inhalation. They are administered through a face mask, laryngeal mask airway or tracheal tube connected to an anesthetic vapo ...
once intubation is complete
Laryngoscopy Laryngoscopy () is endoscopy of the larynx, a part of the throat. It is a medical procedure that is used to obtain a view, for example, of the vocal folds and the glottis. Laryngoscopy may be performed to facilitate tracheal intubation during ...
and intubation are both very stimulating. The process of induction blunts the response to these maneuvers while simultaneously inducing a near-coma state to prevent awareness.


Physiologic monitoring

Several monitoring technologies allow for a controlled induction of, maintenance of, and emergence from general anaesthesia. Standard for basic anesthetic monitoring is a guideline published by the ASA, which describes that the patient's oxygenation, ventilation, circulation and temperature should be continually evaluated during anesthetic. # Continuous electrocardiography (ECG or EKG):
Electrode An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit (e.g. a semiconductor, an electrolyte, a vacuum or air). Electrodes are essential parts of batteries that can consist of a variety of materials d ...
s are placed on the patient's skin to monitor heart rate and rhythm. This may also help the anaesthesiologist to identify early signs of heart
ischaemia Ischemia American and British English spelling differences#ae and oe, or ischaemia is a restriction in blood supply to any tissue (biology), tissue, Skeletal muscle, muscle group, or Organ (biology), organ of the body, causing a shortage of oxyg ...
. Typically lead II and V5 are monitored for arrhythmias and ischemia, respectively. # Continuous
pulse oximetry Pulse oximetry is a noninvasive method for monitoring a person's oxygen saturation. Peripheral oxygen saturation (SpO2) readings are typically within 2% accuracy (within 4% accuracy in 95% of cases) of the more accurate (and invasive) reading o ...
(SpO2): A device is placed, usually on a finger, to allow for early detection of a fall in a patient's
hemoglobin Hemoglobin (haemoglobin BrE) (from the Greek word αἷμα, ''haîma'' 'blood' + Latin ''globus'' 'ball, sphere' + ''-in'') (), abbreviated Hb or Hgb, is the iron-containing oxygen-transport metalloprotein present in red blood cells (erythrocyt ...
saturation with oxygen ( hypoxaemia). # Blood pressure monitoring: There are two methods of measuring the patient's blood pressure. The first, and most common, is non-invasive blood pressure (NIBP) monitoring. This involves placing a
blood pressure cuff A sphygmomanometer ( ), a blood pressure monitor, or blood pressure gauge, is a device used to measure blood pressure, composed of an inflatable cuff to collapse and then release the artery under the cuff in a controlled manner, and a mercury o ...
around the patient's arm, forearm, or leg. A machine takes blood pressure readings at regular, preset intervals throughout the surgery. The second method is invasive blood pressure (IBP) monitoring, which allows beat to beat monitoring of blood pressure. This method is reserved for patients with significant heart or lung disease, the critically ill, and those undergoing major procedures such as cardiac or transplant surgery, or when large blood loss is expected. It involves placing a special type of plastic
cannula A cannula (; Latin meaning 'little reed'; plural or ) is a tube that can be inserted into the body, often for the delivery or removal of fluid or for the gathering of samples. In simple terms, a cannula can surround the inner or outer surfaces ...
in an artery, usually in the wrist ( radial artery) or groin (
femoral artery The femoral artery is a large artery in the thigh and the main arterial supply to the thigh and leg. The femoral artery gives off the deep femoral artery or profunda femoris artery and descends along the anteromedial part of the thigh in the f ...
). # Agent concentration measurement: anaesthetic machines typically have monitors to measure the percentage of inhalational anaesthetic agents used as well as exhalation concentrations. These monitors include measuring
oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as ...
,
carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is trans ...
, and inhalational anaesthetics (e.g.,
nitrous oxide Nitrous oxide (dinitrogen oxide or dinitrogen monoxide), commonly known as laughing gas, nitrous, or nos, is a chemical compound, an oxide of nitrogen with the formula . At room temperature, it is a colourless non-flammable gas, and has ...
, isoflurane). # Oxygen measurement: Almost all circuits have an alarm in case oxygen delivery to the patient is compromised. The alarm goes off if the fraction of inspired oxygen drops below a set threshold. # A circuit disconnect alarm or low pressure alarm indicates failure of the circuit to achieve a given pressure during
mechanical ventilation Mechanical ventilation, assisted ventilation or intermittent mandatory ventilation (IMV), is the medical term for using a machine called a ventilator to fully or partially provide artificial ventilation. Mechanical ventilation helps move a ...
. # Capnography measures the amount of
carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is trans ...
exhaled by the patient in percent or mmHg, allowing the anaesthesiologist to assess the adequacy of
ventilation Ventilation may refer to: * Ventilation (physiology), the movement of air between the environment and the lungs via inhalation and exhalation ** Mechanical ventilation, in medicine, using artificial methods to assist breathing *** Ventilator, a m ...
. MmHg is usually used to allow the provider to see more subtle changes. # Temperature measurement to discern
hypothermia Hypothermia is defined as a body core temperature below in humans. Symptoms depend on the temperature. In mild hypothermia, there is shivering and mental confusion. In moderate hypothermia, shivering stops and confusion increases. In severe ...
or fever, and to allow early detection of
malignant hyperthermia Malignant hyperthermia (MH) is a type of severe reaction that occurs in response to particular medications used during general anesthesia, among those who are susceptible. Symptoms include muscle rigidity, fever, and a fast heart rate. Complica ...
. # Electroencephalography, entropy monitoring, or other systems may be used to verify the depth of anaesthesia. This reduces the likelihood of anaesthesia awareness and of overdose.


Airway management

Anaesthetized patients lose protective airway reflexes (such as coughing), airway patency, and sometimes a regular breathing pattern due to the effects of anaesthetics,
opioid Opioids are substances that act on opioid receptors to produce morphine-like effects. Medically they are primarily used for pain relief, including anesthesia. Other medical uses include suppression of diarrhea, replacement therapy for opioid use ...
s, or
muscle relaxant A muscle relaxant is a drug that affects skeletal muscle function and decreases the muscle tone. It may be used to alleviate symptoms such as muscle spasms, pain, and hyperreflexia. The term "muscle relaxant" is used to refer to two major therap ...
s. To maintain an open airway and regulate breathing, some form of breathing tube is inserted after the patient is unconscious. To enable
mechanical ventilation Mechanical ventilation, assisted ventilation or intermittent mandatory ventilation (IMV), is the medical term for using a machine called a ventilator to fully or partially provide artificial ventilation. Mechanical ventilation helps move a ...
, an
endotracheal tube A tracheal tube is a catheter that is inserted into the Vertebrate trachea, trachea for the primary purpose of establishing and maintaining a patent airway and to ensure the adequate Gas exchange, exchange of oxygen and carbon dioxide. Many diffe ...
is often used, although there are alternative devices that can assist respiration, such as face masks or
laryngeal mask airway A laryngeal mask airway (LMA), also known as laryngeal mask, is a medical device that keeps a patient's Respiratory tract, airway open during anaesthesia or while they are Unconsciousness, unconscious. It is a type of supraglottic airway device. ...
s. Generally, full mechanical ventilation is only used if a very deep state of general anaesthesia is to be induced for a major procedure, and/or with a profoundly ill or injured patient. That said, induction of general anaesthesia usually results in apnea and requires ventilation until the drugs wear off and spontaneous breathing starts. In other words, ventilation may be required for both induction and maintenance of general anaesthesia or just during the induction. However, mechanical ventilation can provide ventilatory support during spontaneous breathing to ensure adequate gas exchange. General anaesthesia can also be induced with the patient spontaneously breathing and therefore maintaining their own oxygenation which can be beneficial in certain scenarios (e.g. difficult airway or tubeless surgery). Spontaneous ventilation has been traditionally maintained with inhalational agents (i.e. halothane or sevoflurane) which is called a gas or inhalational induction. Spontaneous ventilation can also be maintained using intravenous anaesthesia (e.g. propofol). Intravenous anaesthesia to maintain spontaneous respiration has certain advantages over inhalational agents (i.e. suppressed laryngeal reflexes) however it requires careful titration. Spontaneous Respiration using Intravenous anaesthesia and High-flow nasal oxygen (STRIVE Hi) is a technique that has been used in difficult and obstructed airways.


Eye management

General anaesthesia reduces the tonic contraction of the
orbicularis oculi muscle The orbicularis oculi is a muscle in the face that closes the eyelids. It arises from the nasal part of the frontal bone, from the frontal process of the maxilla in front of the lacrimal groove, and from the anterior surface and borders of a short ...
, causing lagophthalmos (incomplete eye closure) in 59% of peoples. In addition, tear production and tear-film stability are reduced, resulting in corneal epithelial drying and reduced lysosomal protection. The protection afforded by Bell's phenomenon (in which the eyeball turns upward during sleep, protecting the cornea) is also lost. Careful management is required to reduce the likelihood of eye injuries during general anaesthesia. Some of the methods to prevent eye injury during general anesthesia includes, taping eyelid shut, use of eye ointment, specialty designed eye protective goggle.


Neuromuscular blockade

Paralysis, or temporary muscle relaxation with a neuromuscular blocker, is an integral part of modern anaesthesia. The first drug used for this purpose was
curare Curare ( /kʊˈrɑːri/ or /kjʊˈrɑːri/; ''koo-rah-ree'' or ''kyoo-rah-ree'') is a common name for various alkaloid arrow poisons originating from plant extracts. Used as a paralyzing agent by indigenous peoples in Central and South ...
, introduced in the 1940s, which has now been superseded by drugs with fewer side effects and, generally, shorter duration of action. Muscle relaxation allows surgery within major
body cavities A body cavity is any space or compartment, or potential space, in an animal body. Cavities accommodate organs and other structures; cavities as potential spaces contain fluid. The two largest human body cavities are the ventral body cavity, and ...
, such as the
abdomen The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the to ...
and
thorax The thorax or chest is a part of the anatomy of humans, mammals, and other tetrapod animals located between the neck and the abdomen. In insects, crustaceans, and the extinct trilobites, the thorax is one of the three main divisions of the cre ...
, without the need for very deep anaesthesia, and also facilitates endotracheal intubation. Acetylcholine, a natural neurotransmitter found at the neuromuscular junction, causes muscles to contract when it is released from nerve endings. Muscle paralytic drugs work by preventing acetylcholine from attaching to its receptor. Paralysis of the muscles of respiration—the diaphragm and
intercostal muscle Intercostal muscles are many different groups of muscles that run between the ribs, and help form and move the chest wall. The intercostal muscles are mainly involved in the mechanical aspect of breathing by helping expand and shrink the size of ...
s of the chest—requires that some form of artificial respiration be implemented. Because the muscles of the larynx are also paralysed, the airway usually needs to be protected by means of an
endotracheal tube A tracheal tube is a catheter that is inserted into the Vertebrate trachea, trachea for the primary purpose of establishing and maintaining a patent airway and to ensure the adequate Gas exchange, exchange of oxygen and carbon dioxide. Many diffe ...
. Paralysis is most easily monitored by means of a peripheral nerve stimulator. This device intermittently sends short electrical pulses through the skin over a peripheral nerve while the contraction of a muscle supplied by that nerve is observed. The effects of muscle relaxants are commonly reversed at the end of surgery by
anticholinesterase Cholinesterase inhibitors (ChEIs), also known as anti-cholinesterase, are chemicals that prevent the breakdown of the neurotransmitter acetylcholine or butyrylcholine. This increases the amount of the acetylcholine or butyrylcholine in the sy ...
drugs, which are administered in combination with muscarinic
anticholinergic Anticholinergics (anticholinergic agents) are substances that block the action of the neurotransmitter called acetylcholine (ACh) at synapses in the central and peripheral nervous system. These agents inhibit the parasympathetic nervous sys ...
drugs to minimize side effects. Examples of skeletal muscle relaxants in use today are pancuronium,
rocuronium Rocuronium bromide (brand names Zemuron, Esmeron) is an aminosteroid non-depolarizing neuromuscular blocker or muscle relaxant used in modern anaesthesia to facilitate tracheal intubation by providing skeletal muscle relaxation, most commonly r ...
, vecuronium, cisatracurium, atracurium, mivacurium, and
succinylcholine Suxamethonium chloride, also known as suxamethonium or succinylcholine, or simply sux by medical abbreviation, is a medication used to cause short-term paralysis as part of general anesthesia. This is done to help with tracheal intubation or ele ...
.Novel neuromuscular blockade reversal agents such as
sugammadex Sugammadex, sold under the brand name Bridion, is a medication for the reversal of neuromuscular blockade induced by rocuronium and vecuronium in general anaesthesia. It is the first selective relaxant binding agent (SRBA). It is marketed by Mer ...
may also be used; it works by directly binding muscle relaxants and removing it from the neuromuscular junction. Sugammadex was approved for use in the United States in 2015, and rapidly gained popularity. A study from 2022 has shown that Sugammadex and neostigmine are likely similarly safe in the reversal of neuromuscular blockade.


Maintenance

The duration of action of intravenous induction agents is generally 5 to 10 minutes, after which spontaneous recovery of consciousness will occur. In order to prolong unconsciousness for the duration of surgery, anaesthesia must be maintained. This is achieved by allowing the patient to breathe a carefully controlled mixture of oxygen and a volatile anaesthetic agent, or by administering intravenous medication (usually propofol). Inhaled anaesthetic agents are also frequently supplemented by intravenous analgesic agents, such as
opioid Opioids are substances that act on opioid receptors to produce morphine-like effects. Medically they are primarily used for pain relief, including anesthesia. Other medical uses include suppression of diarrhea, replacement therapy for opioid use ...
s (usually
fentanyl Fentanyl, also spelled fentanil, is a very potent synthetic opioid used as a pain medication. Together with other drugs, fentanyl is used for anesthesia. It is also used illicitly as a recreational drug, sometimes mixed with heroin, cocain ...
or a fentanyl derivative) and sedatives (usually propofol or midazolam). Propofol can be used for total intravenous anaesthetia (TIVA), therefore supplementation by inhalation agents is not required. General anesthesia is usually considered safe; however, there are reported cases of patients with distortion of taste and/or smell due to local anesthetics, stroke, nerve damage, or as a side effect of general anesthesia. At the end of surgery, administration of anaesthetic agents is discontinued. Recovery of consciousness occurs when the concentration of anaesthetic in the brain drops below a certain level (this occurs usually within 1 to 30 minutes, mostly depending on the duration of surgery). In the 1990s, a novel method of maintaining anaesthesia was developed in
Glasgow Glasgow ( ; sco, Glesca or ; gd, Glaschu ) is the most populous city in Scotland and the fourth-most populous city in the United Kingdom, as well as being the 27th largest city by population in Europe. In 2020, it had an estimated popul ...
, Scotland. Called target controlled infusion (TCI), it involves using a computer-controlled syringe driver (pump) to infuse propofol throughout the duration of surgery, removing the need for a volatile anaesthetic and allowing pharmacologic principles to more precisely guide the amount of the drug used by setting the desired drug concentration. Advantages include faster recovery from anaesthesia, reduced incidence of postoperative nausea and vomiting, and absence of a trigger for
malignant hyperthermia Malignant hyperthermia (MH) is a type of severe reaction that occurs in response to particular medications used during general anesthesia, among those who are susceptible. Symptoms include muscle rigidity, fever, and a fast heart rate. Complica ...
. At present, TCI is not permitted in the United States, but a syringe pump delivering a specific rate of medication is commonly used instead. Other medications are occasionally used to treat side effects or prevent complications. They include antihypertensives to treat high blood pressure;
ephedrine Ephedrine is a central nervous system (CNS) stimulant that is often used to prevent low blood pressure during anesthesia. It has also been used for asthma, narcolepsy, and obesity but is not the preferred treatment. It is of unclear benefit in ...
or
phenylephrine Phenylephrine is a medication primarily used as a decongestant, to dilate the pupil, to increase blood pressure, and to relieve hemorrhoids. In the United States, it was previously used orally as an over-the-counter decongestant to relieve nas ...
to treat low blood pressure; salbutamol to treat
asthma Asthma is a long-term inflammatory disease of the airways of the lungs. It is characterized by variable and recurring symptoms, reversible airflow obstruction, and easily triggered bronchospasms. Symptoms include episodes of wheezing, co ...
, laryngospasm, or
bronchospasm Bronchospasm or a bronchial spasm is a sudden constriction of the muscles in the walls of the bronchioles. It is caused by the release (degranulation) of substances from mast cells or basophils under the influence of anaphylatoxins. It causes di ...
; and epinephrine or
diphenhydramine Diphenhydramine (DPH) is an antihistamine and sedative mainly used to treat allergies, insomnia, and symptoms of the common cold. It is also less commonly used for tremor in parkinsonism, and nausea. It is taken by mouth, injected into ...
to treat allergic reactions.
Glucocorticoids Glucocorticoids (or, less commonly, glucocorticosteroids) are a class of corticosteroids, which are a class of steroid hormones. Glucocorticoids are corticosteroids that bind to the glucocorticoid receptor that is present in almost every vertebr ...
or
antibiotics An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention o ...
are sometimes given to prevent inflammation and infection, respectively.


Emergence

Emergence is the return to baseline physiologic function of all organ systems after the cessation of general anaesthetics. This stage may be accompanied by temporary neurologic phenomena, such as
agitated emergence Emergence delirium is a condition in which emergence from general anesthesia is accompanied by psychomotor agitation. Some see a relation to pavor nocturnus while others see a relation to the excitement stage of anesthesia. Children The pediatri ...
(acute mental confusion),
aphasia Aphasia is an inability to comprehend or formulate language because of damage to specific brain regions. The major causes are stroke and head trauma; prevalence is hard to determine but aphasia due to stroke is estimated to be 0.1–0.4% in t ...
(impaired production or comprehension of speech), or focal impairment in sensory or motor function.
Shivering Shivering (also called shuddering) is a bodily function in response to cold and extreme fear in warm-blooded animals. When the core body temperature drops, the shivering reflex is triggered to maintain homeostasis. Skeletal muscles begin to sh ...
is also fairly common and can be clinically significant because it causes an increase in
oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as ...
consumption,
carbon dioxide Carbon dioxide ( chemical formula ) is a chemical compound made up of molecules that each have one carbon atom covalently double bonded to two oxygen atoms. It is found in the gas state at room temperature. In the air, carbon dioxide is trans ...
production, cardiac output,
heart rate Heart rate (or pulse rate) is the frequency of the heartbeat measured by the number of contractions (beats) of the heart per minute (bpm). The heart rate can vary according to the body's physical needs, including the need to absorb oxygen and excr ...
, and systemic blood pressure. The proposed mechanism is based on the observation that the spinal cord recovers at a faster rate than the brain. This results in uninhibited spinal reflexes manifested as clonic activity (shivering). This theory is supported by the fact that doxapram, a CNS stimulant, is somewhat effective in abolishing postoperative shivering. Cardiovascular events such as increased or decreased blood pressure, rapid heart rate, or other
cardiac dysrhythmia Arrhythmias, also known as cardiac arrhythmias, heart arrhythmias, or dysrhythmias, are irregularities in the heartbeat, including when it is too fast or too slow. A resting heart rate that is too fast – above 100 beats per minute in adult ...
s are also common during emergence from general anaesthesia, as are respiratory symptoms such as
dyspnoea Shortness of breath (SOB), also medically known as dyspnea (in AmE) or dyspnoea (in BrE), is an uncomfortable feeling of not being able to breathe well enough. The American Thoracic Society defines it as "a subjective experience of breathing dis ...
. Responding and following verbal command, is a criterion commonly utilized to assess the patient's readiness for tracheal extubation.


Postoperative care

Postoperative pain is managed in the anaesthesia recovery unit (PACU) with regional analgesia or oral,
transdermal Transdermal is a route of administration wherein active ingredients are delivered across the skin for systemic distribution. Examples include transdermal patches used for medicine delivery. The drug is administered in the form of a patch or ointme ...
, or parenteral medication. Patients may be given
opioid Opioids are substances that act on opioid receptors to produce morphine-like effects. Medically they are primarily used for pain relief, including anesthesia. Other medical uses include suppression of diarrhea, replacement therapy for opioid use ...
s, as well as other medications like non steroidal anti-inflammatory drugs and acetaminophen. Sometimes, opioid medication is administered by the patient themselves using a system called a patient controlled analgesic. The patient presses a button to activate a syringe device and receive a preset dose or "bolus" of the drug, usually a strong opioid such as
morphine Morphine is a strong opiate that is found naturally in opium, a dark brown resin in poppies (''Papaver somniferum''). It is mainly used as a pain medication, and is also commonly used recreationally, or to make other illicit opioids. T ...
,
fentanyl Fentanyl, also spelled fentanil, is a very potent synthetic opioid used as a pain medication. Together with other drugs, fentanyl is used for anesthesia. It is also used illicitly as a recreational drug, sometimes mixed with heroin, cocain ...
, or
oxycodone Oxycodone, sold under various brand names such as Roxicodone and OxyContin (which is the extended release form), is a strong, semi-synthetic opioid used medically for treatment of moderate to severe pain. It is highly addictive and a commonly ...
(e.g., one milligram of morphine). The PCA device then "locks out" for a preset period to allow the drug to take effect, and also prevent the patient from overdosing. If the patient becomes too sleepy or sedated, he or she makes no more requests. This confers a fail-safe aspect that is lacking in continuous-infusion techniques. If these medications cannot effectively manage the pain, local anesthetic may be directly injected to the nerve in a procedure called a nerve block. In the recovery unit, many vital signs are monitored, including
oxygen saturation Oxygen saturation (symbol SO2) is a relative measure of the concentration of oxygen that is dissolved or carried in a given medium as a proportion of the maximal concentration that can be dissolved in that medium at the given temperature. It ca ...
, heart rhythm and respiration, blood pressure, and core body temperature. Postanesthetic shivering is common. Apart from causing discomfort and exacerbating pain, shivering has been shown to increase oxygen consumption,
catecholamine A catecholamine (; abbreviated CA) is a monoamine neurotransmitter, an organic compound that has a catechol (benzene with two hydroxyl side groups next to each other) and a side-chain amine. Catechol can be either a free molecule or a su ...
release, risk for hypothermia, and induce lactic acidosis. A number of techniques are used to reduce shivering, such as warm blankets, or wrapping the patient in a sheet that circulates warmed air, called a bair hugger. If the shivering cannot be managed with external warming devices, drugs such as
dexmedetomidine Dexmedetomidine, sold under the trade name Precedex among others, is a drug used in humans for sedation. Veterinarians use dexmedetomidine for similar purposes in treating cats, dogs, and horses. It is also used in humans to treat acute agitation ...
, or other α2-agonists, anticholinergics, central nervous system stimulants, or corticosteroids may be used. In many cases, opioids used in general anaesthesia can cause postoperative
ileus Ileus is a disruption of the normal propulsive ability of the intestine. It can be caused by lack of peristalsis or by mechanical obstruction. The word 'ileus' is from Ancient Greek ''eileós'' (, "intestinal obstruction"). The term 'subileus' ref ...
, even after non-abdominal surgery. Administration of a μ-opioid antagonist such as alvimopan immediately after surgery can help accelerate the timing of hospital discharge, but does not reduce the development of paralytic ileus. Enhanced Recover After Surgery (ERAS) is a society that provides up-to-date guidelines and consensus to ensure continuity of care and improve recovery and peri-operative care. Adherence to the pathway and guidelines has been shown to associate with improved post-operative outcomes and lower costs to the health care system.


Perioperative mortality

Most
perioperative mortality Perioperative mortality has been defined as any death, regardless of cause, occurring within 30 days after surgery in or out of the hospital. Globally, 4.2 million people are estimated to die within 30 days of surgery each year. An important consi ...
is attributable to complications from the operation, such as
haemorrhage Bleeding, hemorrhage, haemorrhage or blood loss, is blood escaping from the circulatory system from damaged blood vessels. Bleeding can occur internally, or externally either through a natural opening such as the mouth, nose, ear, urethra, v ...
,
sepsis Sepsis, formerly known as septicemia (septicaemia in British English) or blood poisoning, is a life-threatening condition that arises when the body's response to infection causes injury to its own tissues and organs. This initial stage is follo ...
, and failure of vital organs. Over the last several decades, the overall anesthesia related mortality rate improved significantly for anesthetics administered. Advancements in monitoring equipment, anesthetic agents, and increased focus on perioperative safety are some reasons for the decrease in perioperative mortality. In the United States, the current estimated anesthesia-related mortality is about 1.1 per million population per year. The highest death rates were found in the geriatric population, especially those 85 and older. A review from 2018 examined perioperative anesthesia interventions and their impact on anesthesia-related mortality. Interventions found to reduce mortality include pharmacotherapy, ventilation, transfusion, nutrition, glucose control, dialysis and medical device. Interestingly, a randomized controlled trial from 2022 demonstrated that there is no significant difference in mortality between patient receiving handover from one clinician to another compared to the control group. Mortality directly related to anaesthetic management is very uncommon but may be caused by pulmonary aspiration of gastric contents,
asphyxia Asphyxia or asphyxiation is a condition of deficient supply of oxygen to the body which arises from abnormal breathing. Asphyxia causes generalized hypoxia, which affects primarily the tissues and organs. There are many circumstances that ca ...
tion, or
anaphylaxis Anaphylaxis is a serious, potentially fatal allergic reaction and medical emergency that is rapid in onset and requires immediate medical attention regardless of use of emergency medication on site. It typically causes more than one of the foll ...
. These in turn may result from malfunction of anaesthesia-related equipment or, more commonly,
human error Human error refers to something having been done that was " not intended by the actor; not desired by a set of rules or an external observer; or that led the task or system outside its acceptable limits".Senders, J.W. and Moray, N.P. (1991) Human ...
. In 1984, after a television programme highlighting anaesthesia mishaps aired in the United States, American anaesthesiologist Ellison C. Pierce appointed the Anesthesia Patient Safety and Risk Management Committee within the
American Society of Anesthesiologists The American Society of Anesthesiologists (ASA) is an educational, research and scientific association of physicians organized to raise the standards of the medical practice of anesthesiology and to improve patient care. As of 2021, the organizat ...
. This committee was tasked with determining and reducing the causes of anaesthesia-related
morbidity A disease is a particular abnormal condition that negatively affects the structure or function of all or part of an organism, and that is not immediately due to any external injury. Diseases are often known to be medical conditions that a ...
and mortality. An outgrowth of this committee, the Anesthesia Patient Safety Foundation, was created in 1985 as an independent, nonprofit corporation with the goal "that no patient shall be harmed by anesthesia". The rare but major complication of general anaesthesia is malignant hyperthermia. All major hospital should have protocol in place with emergence drug cart near the OR for this potential complication.


See also

* Local anaesthesia


References


External links


Chloroform: ''The molecular lifesaver''
An article at University of Bristol providing interesting facts about chloroform.

* ttps://web.archive.org/web/20051219095333/http://www.rcoa.ac.uk/index.asp?PageID=69 Royal College of Anaesthetists Patient Information page {{DEFAULTSORT:General Anesthesia Anesthesia