User:Ssyang1/sandbox

Evaluating the article


 * Is each fact referenced with an appropriate, reliable reference?
 * Not every fact is referenced, most citations are older than 2005
 * Entirety of paralytics/muscle relaxant use section has no citation, very little in causes and risk factors
 * 1 and 24 are the same reference
 * Is everything in the article relevant to the article topic? Is there anything that distracted you?
 * Is the article neutral? Are there any claims that appear heavily biased toward a particular position?
 * "Most cases of awareness are caused by inexperience and poor anesthetic technique, which can be any of the above, but also includes techniques that could be described as outside the boundaries of "normal" practice" with no citation...biased much?
 * Patient abandonment?!
 * "Factors such as younger age, obesity, tobacco smoking, or long-term use of certain drugs (alcohol, opiates, or amphetamines) may increase the anesthetic dose needed to produce unconsciousness but this is often used as an excuse for poor technique."...with no citation...
 * Where does the information come from? Are these neutral sources? If biased, is that bias noted?
 * Are there viewpoints that are overrepresented, or underrepesented?
 * Patient physiology under-represented (no citation)
 * Check a few citations. Do the links work? Is there any close paraphrasing or plagarism in the article?
 * Is any information out of date? Is anything missing that could be added?
 * Terminology needs to be revised (AAGA, responsive), awareness vs recall)
 * Sources are from 1980-2004
 * Boyle's F models still being used?
 * Monitors just focusing on EEG...doesn't talk much about "newer" technologies that by now have been around for quite a while
 * Which sections will you prioritize during this elective?
 * Intro--needs a better overview
 * Background needs to be tightened up and updated, grammar not the best, talking about neuromuscular blockade in a convoluted way (i.e. incidence is halved in the absence of neuromuscular blockade--makes more sense to use neuromuscular blockade as a risk factor that increases incidence by 2x), multiple points made in background need to be organized better (talks about definition, risks, variability of procedures, signs and symptoms, sequelae, controversies, and patient expectations vs realties)
 * Experiences section not necessary (redundant from background) or should be split up into signs/symptoms and outcomes/complications
 * Language is imprecise (conscious sedation section)
 * Incidence section: may be outdated, weird organization (why start with risk factor?)
 * Outcomes section has a primary study
 * Paralytics/muscle relaxant use: too much irrelevant information about how paralytics work
 * Prevention needs to be developed
 * Memory section too long
 * Cognitive psychologists section necessary?!
 * culture references--fine but needs to be cleaned up
 * What resources do you intend to look up?
 * How will you decide what things (e.g., signs, symptoms, side-effects, etc.) to specifically include or exclude?
 * Will you embed article links to other Wikipedia pages?
 * How will you ensure you avoid "doctor speak" and not use jargon?

Work Plan


 * Article chosen
 * Rationale for choosing the article
 * Initial analysis of the article, including:
 * Where does the information come from?
 * Are the sources neutral?
 * Are there viewpoints overrepresented or underrepresented?
 * Overall organization and planned changes
 * What sections will you prioritize?
 * How will you decide what things (e.g., signs, symptoms, side-effects, etc.) to specifically include or exclude?
 * What will you add or augment?
 * What will you remove or decrease coverage of?
 * How will you ensure you avoid "doctor speak" and not use jargon?

Awareness under anesthesia, also referred to as intraoperative awareness or accidental awareness during general anesthesia (AAGA), is a rare complication of general anesthesia when patients regain varying levels of consciousness during their surgical procedures. While it's possible to regain consciousness during surgery without any memory of it, the more clinically significant entity is awareness with explicit recall, where patients can remember the events related to their surgery. This article focuses on intraoperative awareness with explicit recall.

Intraoperative awareness with explicit recall occurs at an incidence rate of 0.1-0.2%. Patients report a variety of experiences ranging from vague, dreamlike states to being fully awake, immobilized and in pain from the surgery. This is usually caused by the delivery of inadequate anesthetics (purposefully or accidentally) relative to the patient's requirements, resulting in patients waking up and becoming conscious during their procedures. Risk factors for intraoperative awareness include anesthetic factors (i.e. use of neuromuscular blockade drugs, use of intravenous anesthetics, technical/mechanical errors), surgical factors (i.e. cardiac surgery, trauma/emergency, C-sections), and patient factors (i.e. reduced cardiovascular reserve, history of substance use, history of awareness under anesthesia). Currently, the mechanism behind consciousness and memory as related to anesthesia is unknown, although there are many working theories. However, intraoperative monitoring of anesthetic level with bispectral index (BIS) or end-tidal anesthetic concentration (ETAC) can help to reduce the incidence of intraoperative awareness. There are also many preventative techniques that should be considered for high-risk patients, such as pre-medicating with benzodiazepines, avoiding complete muscle paralysis, and managing patients' expectations. Diagnosis is made postoperatively by asking patients about potential awareness episodes and can be aided by the modified Brice interview questionnaire. A common but devastating complication of intraoperative awareness with recall is the development of post-traumatic stress disorder (PTSD) for the conscious events experienced during surgery. Thus, prompt diagnosis and referral to counseling and psychiatric treatment are crucial to the treatment of intraoperative awareness and the prevention of PTSD.

Signs and Symptoms
Intraoperative awareness can present with a variety of signs and symptoms. A large proportion of patients report vague, dreamlike experiences, while others report specific intraoperative events. These events include hearing noises or conversations in the operating room, remembering details of the operation, sensing pain associated with intubation or surgery, having weakness or muscle paralysis, and feeling anxiety, helplessness, or an impending sense of doom. Intraoperative signs that may indicate patient awareness include hypertension (high blood pressure), tachycardia (high heart rate), and patient movement. Recognition of the symptoms of an awareness event may be delayed. One review showed that only about 35% of patients are able to report an awareness event immediately after the surgery, with the rest remembering the experience weeks to months afterward. Distressing experiences can lead to postoperative psychological problems, including post-traumatic stress disorder (PTSD), which is characterized by recurrent anxiety, irritability, flashbacks or nightmares, avoidance of cues related to the trauma, and sleep disturbances.

Causes and Risk Factors
Intraoperative awareness is usually caused by the administration of inadequate anesthetic drugs relative to the patient's requirements, resulting in the patients waking up and becoming conscious during surgery. This under-dosing of anesthesia may be intended or unintended. A low level of anesthesia may be required, or unavoidable, during certain procedures. These include cardiac and emergent surgeries (i.e. where patients may have minimal cardiac reserve and cannot tolerate deep anesthesia) or C-sections (i.e. where light anesthesia is desired to reduce the effects of the drugs on newborns). Other procedures, such as endoscopies or colonoscopies, are performed under conscious sedation or monitored anesthesia care (MAC). These anesthetic techniques are different from general anesthesia, and thus, it is expected that some patients may be aware or conscious during the procedure. However, patients without this expectation may believe they had experienced awareness under anesthesia. Unintended under-dosing of anesthesia may occur in situations where the patient has an individually increased anesthetic requirement relative to the general population (i.e. due to a personal history of substance use). It may also occur due to the use of drugs that make monitoring the depth of anesthesia difficult, or due to equipment failure and/or anesthetist error.

The risk factors for the administration of inadequate anesthesia can be categorized into patient-related factors, surgery-related factors, and anesthesia-related factors.

Patient-Related Risk Factors

 * Chronic substance/medication (opioid, benzodiazepines, cocaine) or alcohol abuse: These patients develop tolerance and thus have a higher dosage requirement for anesthetic drugs. If the anesthetist is not aware of the patient's history with substance or alcohol abuse, this may lead to the administration of an inadequate amount of anesthesia for that particular patient.
 * Chronic pain patients: While these patient are not abusing their medications, they take a lot of medications to manage their chronic pain. Thus, they also have higher tolerance and require a higher dosage of anesthesia.
 * Limited cardiovascular reserve: These patients are very sick and don't have the cardiovascular reserve to tolerate deep anesthesia. For example, giving more anesthesia may dangerously lower their blood pressure. Thus, they can only be given a low dose of anesthetic drugs, which increases the risk of having intraoperative awareness.
 * History of awareness under anesthesia: Those who have experienced intraoperative awareness in the past are more likely to experience it in the future. It is debatable if there is a genetic component to experiencing intraoperative awareness. One study shows a 5x increased risk in patients with a history of awareness under anesthesia.
 * Younger age: Those who are younger, such as kids and teenagers, are at a 8-10x increased risk due to the anesthetic drug being redistributed more rapidly in their bodies. This makes it more difficult for the anesthetist to know for certain what the adequate blood concentration of the anesthetic drug is.

Surgery-Related Risk Factors

 * Cardiac surgeries: Patients undergoing cardiac surgery usually have limited cardiovascular reserve. The hemodynamic instability encountered during the surgery (abnormal heart rate, abnormal blood pressure, potential blood loss) precludes the use of deep general anesthesia. Thus, a low dose of anesthetics is used to maintain hemodynamic stability, but that also increases the risk for intraoperative awareness.
 * Emergency/trauma: In emergency/trauma situations, patients may also be hemodynamically unstable (low heart rate, low blood pressure, significant blood loss), which precludes the use of deep general anesthesia and thus requires light anesthesia, similar to cardiac surgeries. In addition, the time from administration of anesthesia to surgical incision may be shortened in emergent situations, so patients may not yet be fully unconscious for the initial part of surgery.
 * C-sections: During C-sections, a low dose of anesthesia is used purposefully to maintain consciousness in the mother so that she may participate in the birth and to reduce the effect of anesthetic drugs on the newborn.

Anesthesia-Related Risk Factors

 * Use of neuromuscular blockade agent: The use of a neuromuscular blockade agent (i.e. succinylcholine, rocuronium, etc.) has been shown to have a 2x increased risk of intraoperative awareness. These agents are muscle relaxants that cause paralysis, which facilitate intubation and are required by certain surgeries. When patients are paralyzed, they are unable to move, speak, or respond to pain. In this setting, if they become conscious during surgery, they are unable to signal their consciousness to the OR staff. They can, however, still exhibit physiological signs of distress, such as high blood pressure and high heart rate (see Signs and Symptoms). However, without patient movement or obvious response to surgical stimuli, the anesthetist may not detect clinical signs of consciousness and may not deepen the anesthesia. The use of a neuromuscular blockade agent is the most important risk factor for the development of PTSD, as being aware while being completely paralyzed is usually an extremely distressing experience.
 * Use of total IV anesthesia (TIVA): When using all IV anesthetics, there is no way to measure the blood concentration of the drug. As a result, there is a high risk of under-dosing the anesthetics and causing intraoperative awareness.
 * Not pre-medicating with benzodiazepines: Benzodiazepines are drugs used before surgery for their sedative, hypnotic (sleep-inducing), anxiolytic (anti-anxiety), and amnesic properties. These drugs can prevent memory formation, so if they are not used prior to the procedure, there is an increased risk of patients remembering their intraoperative awareness event.
 * Difficult intubations: Difficulties during intubation can prolong the induction process and extend the time until patients are able to receive inhaled anesthetics. The initial short-acting anesthetics given to facilitate intubation may wear off during a difficult intubation, increasing the risk that patients may regain consciousness and feel the pain associated with intubation.
 * Equipment failure/mechanical errors: Machine and equipment failure may cause intraoperative awareness from the failed delivery of adequate anesthetics.
 * Technical/human errors: Lapse in judgment or human mistakes on the part of the anesthetist may also result in the under-dosing of anesthetics, thus causing intraoperative awareness.

May be unavoidable in hemodynamically unstable pateints (trauma or cardiac) (1)

light anesthesia and machine malfunction (3)

Surgical factors: C section, cardiac, emergency, trauma (1), hemodynamic instability during trauma/cardiac precludes use of deep GA (4), incidence up to 40% (Phillips, Bogetz), C section-light anesthesia needed to reduce effect on newborn, up to 0.4% (4) (Lyons)

Anesthestic factors: RSI, reduced doses, difficult intubations, TIVA, use of NO-opioid anesthetic techique (1), inadequate dosing (2), NMB*** (3), misues of equipment or human error (4)


 * Rapid sequence induction: This is a quickened process of induction and intubation to help prevent aspiration events. Due to the short and quick process, a patient may not be
 * Rapid sequence induction: This is a quickened process of induction and intubation to help prevent aspiration events. Due to the short and quick process, a patient may not be

Patient factors: chronic substance abuse (opioid, benzo, cocaine)---develop resistance and have higher requirement dosages, ASA IV or V, limited hemodynamic reserve, hx of awareness (1) (Aranake), women (2,3), high individual requirement for anesthestics (4)

Patients may complain of it when they are actually under MAC or regional, need a good discussion with anesthesia staff, awareness is expected for those undergoing MAC (2)

Association between red hair and MAC, but none between red hair and recovery time, postop pain, introp awarness outcomes (4) (Gradwohl)

Many cases of awareness appear to occur during prolonged attempts at airway intubation when the hypnotic effect of intravenous induction agents wears off while patients remain paralyzed with a muscle relaxant (4)

Other reports have described awareness when anesthetic vaporizers were empty or when infusion pumps were not delivering intended doses of hypnotic agents.(4) (Bergman)

Diagnosis
Modified Brice (3)

Intraop awareness cannot be measured, recall can only be deteremined postop

Clinical technqiues to assess: checking for patient movement, response to voice commands, eye opening, lash reflex, ppapillary response, perspiration, teraing

EKG, BP, HR, ETAC

BIS: proprietary algorithm applied to frequency, amplitude, and latency relationship from EKG to generate index number (0 to 100), 100 is awake, 0 is isoelectric EEG and deep sedation), 40-60 means low probability of consciousness under GA, RCTs show decrease incidence of explicit recall, times to awakening, first response, eye opening, consumtpion of anesthestic drugs, others have shown no effect, current data and rec mixed

-things that affect it: cerebral hypoperfusion, gas embolism, hemorrhage, use of muscle relaxants, activation of electromagnetic equipment, patient warming, hypothermia

AEP: auditory-evoked potentials, electrical responses of brainstem, auditory radiation and auditory cortext o sound stimuli delivered via headphonses, analysis of AEP waveform--AEP index (low probability of consciousness <25)

Case by case basis under conditions that place them at risk/pt requires smaller doses of anesthestics (trauma, C-section, TIVA), insufficient evidence

Prevention
During preinduction

-Checking machine (1)

-Prophy benzo (midaz, from RCT) (1), when light anesthesia is unavoidable (4)

-no paralysis unless indicated by surgery (3)

Intraop monitoring (1)

only 2 strategies have shown effectiveness in reducing incidence (4)

BIS: EEG based (4), B-AWARE trial (MYles)

ETAC (4) --READ more

intraop benzos (1)

N2O-relaxant anesthesia supplemented with volatile or IV anesthetic agents to maintain adequate hypnosis (4)

When intubation delayed/require several attempts, supplement induction boluses w/ additioanl inahled or IV hypnotic agents (4)

Postop interview, questionaires, conseling, psychological support (1)

Postop period discussion (4) -- READ more

Prevention begins with recognizing and addressing risk factors (4)

Talk to patients (4), informed consent

High risk patients get ETAC and EEG based monitoring (4)

Treatment
Referral to psych (3)

psychotherapy for PTSD (3)

Outcomes/Prognosis
Modified Brice questionnaire (3)

PTSD is characterized by recurrent episodes of anxiety, irritability, anger, and vigilance, often associated with flashbacks or nightmares, avoidance of cues related to the trauma, and sleep disturbances (4), incidence unknown, related to duration of the awareness episode and the presence of pain, anxiety, and preexisting psychological problems, more than 50% in survey (Whitlock and Osterman)

Kids rarely develop PTSD altho they report intraop awareness more often (4) (Lopez)

Epidemiology (Incidence, prevalence, age distribution, sex ratio)
0.1-0.2%

Sweden study

US study: 31,360 patients, 40 cases of “definite” and “probable” awareness with recall were identified, an incidence of 0.13%. Given that 30 to 50 million general anesthetics are administered in the United States, the number of patients experiencing awareness with recall is estimated at around 50,000 per year. (4)