Anesthesia works in 5 ways:

1. analgesic (pain reliever)
2. amnesiac (loss of memory)
3. promotes unconsciousness
4. immobility of the patient
5. elimination (or reduction) of autonomic responses such as tachycardia (increased heartbeat), increased breathing, hypertension, lacrimation (tear production)

autonomic nervous system
(noun)
: a part of the vertebrate nervous system that innervates smooth
 and cardiac muscle and glandular tissues and governs involuntary 
actions (as secretion, vasoconstriction, or peristalsis) and that consists
 of the sympathetic nervous system and the parasympathetic nervous system
(Merriam-Webster Medical)

The obstruction of sensory, reflex, mental and motor functions are needed to safely and effectively operate on a patient. There are inhalation and intravenous General anesthetics or a combination of both agents can be used.  The laws of Gas such as Dalton's partial pressure law and Henry's law will be utilized to calculate the concentration of an anesthetic in its gas phase from the partial pressure of the anesthetics to better understand the body's reaction and submission to inhalation of General anesthesia. Of course you don't need to know all this scientific jargon because that is the anesthesiologist's responsibility. Hence the adamancy regarding proper certification. Ascertain that your anesthesiologist is fully qualified and fully  certified or at minimum, a CRNA, to safely administer any type of anesthesia to you. This is very important. However for some types of anesthesia such as versed and fentanyl, there is no need for an actual anesthesiologist - just an OR tech who repeatedly says your name over and over to make sure you are under completely as well as checks your fingernails and toenails. The nails turn blue with lack of oxygen and red with excess carbon dioxide.

These factors are what makes it possible for anesthesia to "work". This information has been provided for you so you won't feel overwhelmed when you discuss anesthesia with your surgeon.

Your Choices In Anesthesia
There are a few choices that you may have for anesthesia although not all surgeons and their practices will offer every one. 

The four main categories of anesthesia are:

• local anesthesia
• regional anesthesia 
• sedation 
• general anesthesia 

Local anesthesia: is what you have when you receive a shot to numb the immediate area where the "work" will be performed. You most commonly receive local at the dentist's office but also receive it during a rhinoplasty or other type of surgery in addition to Sedation or General. 

The injection is most commonly of Lidocaine (or Xylocaine), epinephrine (as a vasco-constrictor to impede bleeding) in a saline carrier. Local anesthesia is thought to block nerve impulses by decreasing the permeability (think of microscopic openings for a substance to leak through) of nerve membranes to sodium ions. There are many different local anesthetics that differ in absorption, toxicity, and duration of action. There is a possibility of Lidocaine Toxicity - which we will discuss more on this later on.

You can also obtain the benefits of local anesthesia by using a topical agent, or ectatic mixture of local anesthetics (EMLA) cream which contains lidocaine and prilocaine to numb the mucus membranes or broken skin area before a procedure such as injectable fillers, micropigmentation or other minimally invasive procedures. The white EMLA cream is applied and covered and then an hour must go by before undergoing the procedure for optimum anesthetic effects. For some procedures it is more of a hassle to anesthetize with an EMLA than to stand the pain itself. Believe it or not brain surgery is performed under Local anesthesia (to the scalp) so that the patient can be awake to assist the surgeon when a specific cut or correction is made - testing for the existence of senses after a certain move, etc. 

However EMLA is beginning to be considered "old fashioned" as you can now get "Ela-Max". It is cheaper, available over the counter (OTC), faster and doesn't have to be occluded (covered). It contains 4% Lidocaine and is making it's way to a surgeon near you.

Regional anesthesia: was named such because a "region" of the body is anesthetized without rendering the patient unconscious. For instance, spinal anesthesia for childbirth. Do not get this confused with an epidural as they are very similar in effects but a different locale is injected with the anesthetic. In an epidural the injection is in the area outside the spinal fluid called the epidural space, the catheter is placed inside this area so that anesthetic injections may be given or can be tube-fed if needed for longer periods of time (from hours to weeks). With spinal anesthesia, the local anesthetic is injected into the spinal fluid that causes a loss of sensation to the areas below the navel. Also, in spinal anesthesia, such narcotics as morphine and fentanyl can be infused in addition to or partially substituting the anesthesia.

You may have heard of nerve blocks. A nerve block is considered regional as an anesthetic is injected into a nerve cluster. There are nerve clusters all of your body - for instance, under the jaw, in the chin, and under the eye. They sometimes feel like little holes in the bone where your nerves are "clustered", then branch out to the different areas of the face or anywhere on the body. 

Sedation: can be gas, oral or intra-venous (IV). Most common are liquids such as versed. This is where a sedative such as Valium may be given ahead of time as well as a liquid formulation for the main event - a catheter is inserted into the vein of the hand or arm and a mixture of saline (as a carrier), Versed and DIPRIVAN or Ketamine and a few other additives for a nice "sedative cocktail". They can customize the concoction specifically for the patient. Say if a little epinephrine is needed to help the senses or heart (which is essentially speed or an adrenalin-type medication). You may feel this sometimes if you have had asthma shots or go to the dentist and have gotten a shot to numb the area. It feels like you are cold and shaking afterwards if you are sensitive to it (like me). You are usually given Sedation with Local as well. The Sedation helps with the anesthetic properties - ease of mind, loss of memory, etc. with the benefits Local for pain relief after you awaken and intra-operatively for impediment of bleeding (bruising).

You may have had "laughing gas" (nitrous oxide) before for dental work or OBGYN matters. It is an inhaled gas, actually low doses of the same gases for General anesthesia, that incorporate the pain relief, the amnesiac properties as well as the other 3 that are important in invasive surgery but are not as strong so a sedative or local or even regional may be administered as well. The good thing about nitrous oxide is when they take the mask off, you are back to "normal" a few minutes later but still with no pain if you had the local anesthetic as well - which is more probable than not.

A few liquid anesthetics like the Versed and Ketamine can be taken orally, but some can be inserted via the rectum with a small lubricated tube or even inhaled like a nasal spray. 

General Anesthesia: General can be given by an inhaled gas or by a liquid. General isn't fully understood, yet. But they speculate that it works in several ways:

• neuromuscular blocking agents which effect the spinal cord (resulting in immobility of the patient)
• "brain-stem reticular activating system" (resulting in unconsciousness) 
• cerebral cortex (as seen as changes in electrical activity on an electroencephalogram)
• Inhalational agents to control autonomic responses and provide analgesia and amnesia
   (or)
• Benzodiazepines (such as Valium - my favorite) for their anti-anxiety and amnesiac effects
• obstruction of nerve conduction
• interruption of synaptic transmission (It is more difficult to explain synapses interruption, so take my word for it - I don't even remotely understand it yet.

Total Intravenous Anesthesia (or TIVA) is intravenous sedation only - it's what I prefer with Light Sleep by Versed, etc. This is done without a TCI pump and the anesthesiologist calculates the needed dosage by skill and experience with the weight factors.

Gas Or Liquid? Inhaled, Injected Or Swallowed?
Anesthesia in a gaseous state is inhaled into the lungs; the blood that travels to the lungs for oxygenation is then saturated by the oxygen and anesthetic gas "absorbed" by your aveoli (the little spongy things in your lungs that grab oxygen out of the air) which is then carried to the central nervous system (CSN). The effects of the anesthesia and the rate at which they affect the patient are dependent upon these factors:

• gas concentration
• rate of gas flow from the anesthesia machine
• rate/depth of breathing (that's why they say "breathe deeply")
• amount of blood the patient's heart pumps each minute
• solubility of the gas in the patient's blood (some gases are more soluble than others)

Some inhalants are:

• Enflurane
• Halothane
• Isoflurane
• Sevoflurane
• Desflurane

Once the anesthesiologist turns off the anesthetic gas and only delivers pure oxygen; or alternatively removes the mask entirely (as in gaseous state "Twilight", Laughing Gas), the blood stream returns the gases to the lungs where it is then eliminated by exhalation. However, the more soluble the gas is in blood, the longer it will take to purge from the body. Nitrous oxide and desflurane are the shortest in duration of the available anesthetic gases and soon after the gas concentration is turned off - viola! you wake up! Halothane or sevoflurane are "stronger" and work rather fast but they also take longer to expel from the body. Usually these two are utilized first to render the patient unconscious then the anesthesiologist changes over to the desflurane.

Regardless you will more than likely require a urinary catheter to "catch" any accidental urinating. They usually insert the catheter after you are already under. I had mine inserted without anything - straight insertion for a kidney infection. You, thankfully, will be oblivious of the whole event.

Anesthesia in a liquid, injectable state is administered by injection directly into the bloodstream, usually through an intravenous catheter (IV). Some of these anesthetics include:

barbiturates such as: 

• Propofol: (DIPRIVAN^® Injectable Emulsion is one name brand - which is what I prefer with Versed) "Widely used anaesthetic induction agent with slightly slower onset than thiopentone, a greater tendency to drop blood pressure. The rapid, pleasant offset makes it suitable for monitored sedation, maintenance of anaesthesia, and patient sedation in ICU. Pain on injection is probably pH related and can be ameliorated by addition of plain lignocaine (2-5ml of 1% to 20ml propofol works fine. New target controlled infusion (TCI) technique makes continuous administration easier" (Virtual Anesthesia Textbook) *please read below!
• Ketamine: "An intravenous NMDA-receptor antagonist anesthetic agent with analgesic, intoxicating and dissociative hallucinatory properties. Associated catecholamine output which masks cardiac depression. Potent analgesic properties, mild respiratory depresion and some maintenance of muscle tone. Can be used as a total intravenous anesthetic, particularly useful for trauma or field situations. Recreationally abused (referred to as "vitamin K") for intoxicating and hallucinatory effects. These same effects are undesirable after anesthesia. Some interest in use of low doses with general anesthesia to inhibit NMDA-receptor associated nocioceptive 'wind-up'. Limited cerebral protection." (Virtual Anesthesia Textbook)
• Etomidate: "An induction agent presented in propylene glycol with less cardiovascular depression than thiopentone. Causes pain on injection, occasional involutary movements, suppresses cortisol production. Depresses cerebral metabolism but conflicting evidence for cerebral protection. (Virtual Anesthesia Textbook)
• Pentothal (sodium thiopental, thiopentone, aka sodium Pentothal): "...Main advantage of thiopentone is rapid onset and lesser tendency than propofol to drop blood pressure". (Virtual Anesthesia Textbook) This was once very popular but is losing to Propofol. 

Eventually there will be "Target Controlled Infusion (TCI) machines in which a microprocessor-controlled syringe pump automatically and variably controls the rate of infusion of a drug to attain a user defined target level in an effect site in the patient (usually blood). This greatly simplifies maintenance of a steady blood level. At present commercial TCI systems are only available for propofol." 

analgesic narcotics (or opioids) such as:

• Alfentanyl
• Anileridine
• Buprenorphine
• Butorphanol
• Codeine
• Dextromoramide
• Diamorphine
• fentanyl (most common) 
• Hydrocodone
• Hydromorphone (rarely used! this is a synthetic heroin, aka Dilaudid)
• Levorphanol
• Meperidine/Pethidine
• Methadone
• morphine
• Nalbuphine
• Nalmefene
• Naloxone
• Naltrexone
• Oxycodone
• Pentazocine
• Propoxyphene, Dextropropoxyphene
• Sufentanil
• Tramadol (weak opiod action but prevents noradrenaline and serotonin reuptake (which is similar to a number of antidepressant agents)

benzodiazepines like:

• Valium
• Diazapam (which is a generic version of valium)
• Versed is also considered in this category

Flumazenil: (used for reversal of anesthesia/reversal of conscious sedation) "Flumazenil is a specific benzodiazepine antagonist which may be used to promptly reverse or attenuate benzodiazepine-induced sedation or anesthesia, usually postoperatively or in the intensive care unit. Flumazenil is also useful in the management of the patient presenting a suspected benzodiazepine overdose, has had anecdotal success in the treatment of hepatic encephalopathy, and can be used for intra-operative "wake-up" testing (e.g., to test for neurological intactness during back surgery)...Flumazenil does not antagonize the CNS effects of opioids, ethanol, or, propofol" (D. John Doyle MD PhD FRCPC Department of Anaesthesia, The Toronto Hospital)

Just like gases, the effects and duration depend on a few factors such as the amount injected, the weight of the patient, the fat-solubility of the drug and the fat percentage of the patient's body as well as the patient's body and how it reacts to drugs. Pentothal (sodium thiopental) is fat soluble and its effects are felt soon after injection. 

Used in small doses most of these can be used for Light Sleep Sedation or Twilight.

Why Shouldn't I Eat Before Surgery?
You are often told "don't eat past midnight the night before your surgery" but perhaps only a few sips of water. To better explain this to you, this is best said by the American Society of Anesthesiologists Guidelines on Sedation and analgesia by Non-Anesthesiologists

Example of Fasting Protocol for Sedation and Analgesia for Elective Procedures:

Gastric emptying may be influenced by many factors, including anxiety, pain, abnormal autonomic function (e.g., diabetes), pregnancy, and mechanical obstruction. Therefore, the suggestions listed do not guarantee that complete gastric emptying has occurred. Unless contraindicated, pediatric patients should be offered clear liquids until 2  to 3 hours before sedation to minimize the risk of dehydration.

age	Solids and Nonclear Liquids*	Clear Liquids
Adults	6 to 8 h or none after midnight1	2  to 3 h
Children older than 36 months	6  to 8 h	2  to 3 h
Children aged 6  to 36 months	6 h	2  to 3 h
Children younger than 6 months	4  to 6 h	2 h

* This includes milk, formula, and breast milk (high fat content may delay gastric emptying).
¹ There are no data to establish whether a 6  to 8 h fast is equivalent to an overnight fast before sedation/analgesia. American Society of Anesthesiologists Guidelines on Sedation and analgesia by Non-Anesthesiologists, source: www.GasNet.org

Well, What Does It Feel Like?
Injectable liquid anesthesia (IV Sedation): If you had been given an oral sedative or valium prior you usually could care less what they are sticking in you.  If you haven't been given a sedative, it is less stressful for some patients. It feels sort of like blood being drawn, but for a shorter period of time. It's the initial placement of the IV catheter that may sting a bit. After the needle is injected into the vein it is pulled out and a little plastic tube is left in your vein. The catheter is taped to your skin so it is not knocked out and is ready to be used as a sort of "doorway" for anything they deem suitable for your body. This is usually done before you get into the actual O.R. - by a nurse - and you have a saline bag hooked up to you. The medications will be given with a drip system with this saline. The saline will keep you hydrated both during and post-operatively.

Some people get it in the crook of the elbow, some the hand. I dislike the hand ones as it's a nasty place for a bruise to be, at least with the arm you can hide it - it all depends upon your veins. 

You are then brought to the O.R. if you aren't on the table yet. They insert a hypodermic into your tube that you are attached to or they attach the bag of it with a drip system to add a few drops every few minutes and when they spring open the stopper and it starts heading towards your body. The the effects of the anesthesia are felt soon after injection or opening the stopper - a few seconds in fact. It feels like "heat" going into you veins then creeping up your arm - then it "jumps" from your shoulder to a metallic-like taste under your tongue and then you are anesthetized. 

Gaseous-state anesthesia (Twilight, Gaseous General): All this entails is breathing through a mask. However this depends upon what type. The newer types fit over your mouth and nose  usually and force air into your lungs. Then again, Twilight or Laughing Gas can be given via a mask. With the older intubation you have the pleasure of having a tube down your throat but you don't usually remember it going in. You may wake up with a raw throat. You may wake up with a sore, dry throat regardless because "canned" or cylinder air (scubadiving tanks as well) is d-r-y. There is no moisture in these tanks. It is your turbinates (three little fleshy flaps in your sinuses) inside your nasal structure that moisturizes the air which you breathe. Also be advised that if you have bronchospasm, asthma or other disorders such as this, intubation is contraindicated. Please make sure you read the risks associated with Anesthesia, below.

click for a larger image

You basically are told to count down from 100, and see how far you can make it - usually 97. After the gas hits the aveoli in your lungs, your blood is saturated by the anesthesia gases where they are carried to your central nervous system (CNS) where you are then blissfully anesthetized. 

Your Anesthesiologist
If you are going under General deep sedation, it is usually best to choose a surgeon who will have a separate anesthesiologist - this is important. The anesthesiologist basically must know for your weight and body fat percentage what will work best for you and in what amounts plus they monitor your heart rate, breathing rate, your blood pressure, etc. and stand there and say your name over and over so that if you answer or stir they know you aren't getting enough anesthesia.

To become an anesthesiologist, a person must complete:

• college

• medical school

• internship

• three-year anesthesiology residency

Recovery From Anesthesia
This is very important. Many things can go wrong during initial recovery. The shivering and feeling cold is the least of your worries. Please read the below information and discuss the regarding your surgeon's anesthesia protocol.

• "Patients must be monitored during recovery to ensure that any adverse events are rapidly recognized and treated.
  
• Vital signs should be recorded at regular intervals and pulse oximetry should be continued until the patient is no longer at risk of hypoxemia.
  
• Monitoring should include observation by a person trained in recognition of post-procedure/post-sedation complications.
  
• Appropriate discharge criteria should be met prior to discharge.
  
  

  Example of Recovery and Discharge Criteria after Sedation and Analgesia Each patient care facility in which sedation/analgesia is administered should develop recovery and discharge criteria that are suitable for its specific patients and procedures. Some of the basic principles that might be incorporated in these criteria are enumerated. General Principles 1. All patients receiving sedation/analgesia should be monitored until appropriate discharge criteria are satisfied. The duration of monitoring must be individualized depending on the level of sedation achieved, overall condition of the patient, and nature of the intervention for which sedation/analgesia was administered. 2. The recovery are should be equipped with with appropriate monitoring and resuscitation equipment. 3. A nurse or other trained individual should be in attendance until discharge criteria are fulfilled. An individual capable of establishing a patient airway and providing positive pressure ventilation should be immediately available. 4. Level of consciousness and vital signs (including frequency and depth of respiration in the absence of stimulation) should be recorded at regular intervals during recovery. The responsible practitioner should be notified if vital signs fall outside of the limits previously established for each patient. Guidelines for Discharge 1. Patients should be alert and oriented; infants and patients whose mental status was initially abnormal should have returned to their baseline. Practitioners must be aware that pediatric patients are at risk for airway obstruction should the head fall forward while the child is secured in a car seat. 2. Vital signs should be stable and within acceptable limits. 3. Sufficient time (up to 2 h) should have elapsed after last administration of reversal agents (naloxone, flumazeil) to ensure that patients do not become resedated after reversal effects have abated. 4. Outpatients should be discharged in the presence of a responsible adult who will accompany them home and be able to report any post-procedure complications. 5. Outpatients should be provided with written instructions regarding post-procedure diet, medications, and activities, and a phone number to use in case of emergency."

Recovery Care - Adapted from the American Society of Anesthesiologists Guidelines on Sedation and analgesia by Non-Anesthesiologists, source: www.GasNet.org

Risks, Contraindications & Complications of Anesthesia
Causes of anesthesia-related death are usually linked to the respiratory system. These include insufficient intubation or proper ventilation which results in hypoxia:

hypoxia
hyp*ox*ia (noun)
[New Latin] First appeared 1941
: a deficiency of oxygen reaching the tissues of the body
-- hyp*ox*ic (adjective)
(Meriam-Webster)

But this was usually because the older monitors were not very good. Medical Science has progressed very much in that respect. 

Complications are mostly related to General Gaseous-state anesthesia and may include:

• laryngospasm: la*ryn*go*spasm (noun) : spasmodic closure of the larynx 

• bronchospasm: bron*cho*spasm (noun) : constriction of the air passages of the lung (as in asthma) by spasmodic contraction of the bronchial muscles 

• aspiration: as*pi*ra*tion (noun) 3 : the taking of foreign matter into the lungs with the respiratory current 

• intubation injury: The teeth, lips, pharynx, esophagus, larynx and trachea may be injured by the tube which is placed down your throat.

• pulmonary edema: pul*mon*ary e*dem*a (noun) : abnormal accumulation of fluid in the lungs

• respiratory arrest: (noun) Cessation of breathing. the condition of being stopped

Cardiovascular complications:

• myocardial ischemia/infarction,: of or relating to the myocardium: myo*car*di*um plural -dia  (noun): the middle muscular layer of the heart wall

  • myocardial ischemia (noun) : localized tissue anemia due to obstruction of the inflow of arterial blood (as by the narrowing of arteries by spasm or disease) 

  • myocardial infarction (noun) : infarction of the myocardium that results typically from coronary occlusion

• cardiac failure: *see heart failure: (noun) 1 : a condition in which the heart is unable to pump blood at an adequate rate or in adequate volume

• cardiac arrest: (noun) : temporary or permanent cessation of the heartbeat which may be secondary to an underlying respiratory problem.

• emboli: em*bo*lus (plural -li) (noun) : an abnormal particle (as an air bubble) circulating in the blood

  • possible causes:

    • clots

    • air bubbles

    • orthopedic stimuli

• hypotension: hy*po*ten*sion (noun) 1 : abnormally low pressure of the blood -- called also low blood pressure...

  • possible causes:

    • hypovolemia: (noun) : decrease in the volume of the circulating blood 

    • massive hemorrhage: massive bleeding

    • anaphylaxis: (noun) 1 : hypersensitivity (as to foreign proteins or drugs) resulting from sensitization following prior contact with the causative agent. Also affects the pulmonary system (lungs)

    • drug overdose

• malignant hyperthermia: (noun) : a rare inherited condition characterized by a rapid, extreme, and often fatal rise in body temperature following the administration of general anesthesia 

• machine malfunction

• liver or kidney injury

• stroke: (noun) : sudden diminution or loss of consciousness, sensation, and voluntary motion caused by rupture or obstruction (as by a clot) of an artery of the brain

• ventricular tachycardia (rapid heartbeat of 100-200 bpm)
  • possible causes:
    • hypoxia: (noun) : a deficiency of oxygen reaching the tissues of the body 
    • Increased CO2: increased carbon dioxide
    • Decreased K+ (vitamin K) : (noun) 1 : either of two naturally occurring fat-soluble vitamins that are essential for the clotting of blood because of their role in the production of prothrombin in the liver and that are used in preventing and treating hypoprothrombinemia and hemorrhage: 
    • Digitalis toxicity
    • Acid-base imbalance (see Acidosis): (noun) : a condition of decreased alkalinity of the blood and tissues marked by sickly sweet breath, headache, nausea and vomiting, and visual disturbances and usu. a result of excessive acid production
• electromechanical dissociation (EMD) ("Clinically, a description of EMD covers a spectrum of bradycardic (relatively slow heart action whether physiological or pathological), to tachycardic (relatively rapid heart action whether physiological (as after exercise) or pathological), arrhythmias associated with pulselessness (excluding V-Tach or V-Fib). 
  *According to new AHA guidelines, EMD is now known as PEA (Pulseless Electrical Activity" J Bergsbaken, University of Wisconsin).
  • possible causes:
    • Hypovolemia
    • Hypoxia: (noun) : a deficiency of oxygen reaching the tissues of the body 
    • Cardiac tamponade: (noun) : mechanical compression of the heart by large amounts of fluid or blood within the pericardial space that limits the normal range of motion and function of the heart 
    • Tension pneumothorax: (noun): pneumothorax resulting from a wound in the chest wall which acts as a valve that permits air to enter the pleural cavity but prevents its escape
    • Pulmonary embolus: a clot that reaches and affects the lungs (plural: pulmonary emboli)
    • Acidosis: (noun) : a condition of decreased alkalinity of the blood and tissues marked by sickly sweet breath, headache, nausea and vomiting, and visual disturbances and usu. a result of excessive acid production
    • Hyperkalemia: (noun) : the presence of an abnormally high concentration of potassium in the blood -- called also hyperpotassemia 
    • Hypothermia: (noun) : subnormal temperature of the body. *some surgeons automatically wrap you in thermal or thermal-compression blankets to keep your blood circulating well and your body warm)

Lidocaine Toxicity:
Lidocaine toxicity is something that can occur with way too many injections of Lidocaine. A common procedure requiring vast amounts of Lidocaine is Tumescent and Super-Wet Technique Liposuction.

"Maximum dose of plain lidocaine is 5mg/kg (7mg/kg max dose for lidocaine with epinephrine).  So for a 30-kg patient the maximum is 150 mg total.  A concentration of 1% means 1 gm lidocaine per 100cc which equals 10mg/cc.  Total volume which can be injected is therefore: 15cc.

Lidocaine freely crosses the blood-brain barrier. Early symptoms are CNS-related including headache, tinnitus, restlessness, facial twitching, lightheadedness, metallic taste, numbness of the lips and tongue.  At higher dose levels, one may see: seizures, loss of consciousness, apnea, and CV collapse.  CV manifestations are rarer; these are related to direct myocardial depression through depression of vascular smooth muscle and conducting system.  At very high doses, one will see: hypotension, labile heart rate, and v-fib arrest.

Treatment for seizures: hyperventilate with 100% O₂, diazepam (thiopental if symptoms persist).  Treat low blood pressure with fluids, trendelenberg, and pressors if required.  Arrhythmia may be refractory (inadvertant IV marcaine) and require prolonged rescuscitation.

Mechanism of local anesthetics is by blocking nerve conduction.  Anesthetic diffuses passively through cell membrane, becomes charged, blocks Na⁺ channel, and prevents action potential." Yale Medical University Core Curriculum

"- Pre-existing cardiac or pulmonary disease may require reduced dosage because sedative and analgesic medications tend to cause cardiovascular and respiratory depression.

- Hepatic and renal abnormalities may impair drug metabolism and excretion resulting in longer duration of drug action." Adapted from the American Society of Anesthesiologists
Guidelines on Sedation and analgesia by Non-Anesthesiologists, source: www.GasNet.org

Smoking Tobacco & Illegal Substances

"- Smoking increases risk of airway irritability, bronchospasm, or cough during sedation. "Adapted from the American Society of Anesthesiologists
Guidelines on Sedation and analgesia by Non-Anesthesiologists, source: www.GasNet.org

Physical Disorders or Attributes

"- Previous problems with anesthesia or sedation

- Stridor, snoring, or sleep apnea

- Dysmorphic facial features (e.g. Pierre-Robin syndrome, trisomy 21)

- Advanced rheumatoid arthritis

- Habitus (extreme obesity)

- Small opening (<3 cm in an adult); edentulous [toothless], protruding incisors; loose or capped teeth; high arched palate; macroglossia; [enlarged tongue] tonsillar  hypertrophy [enlarged tonsils]; nonvisible uvula [: the pendent fleshy lobe in the middle of the posterior border of the soft palate; or in English: the little thing that hangs in the back of your mouth]

- Micrognathia [: abnormal smallness of one or both jaw], retrognathism [: a condition characterized by recession of one or both of the jaws], trismus [: spasm of the muscles of mastication (chewing) resulting from any of various abnormal conditions or diseases (as tetanus) ], significant malocclusion [: improper occlusion (bringing together); esp : abnormality in the coming together of teeth]"

Adapted from the American Society of Anesthesiologists Guidelines on Sedation and analgesia by Non-Anesthesiologists, source: www.GasNet.org

Medication and Supplement Contraindications Regarding Anesthesia
There are some medications and supplements that you simply should not be consuming before and after going under anesthesia, although this may be a partial list PLEASE talk this over with your surgeon!!!

• Ginseng may cause rapid heartbeat/and or high blood pressure in some individuals.
• St. John's Wort, Yohimbe, ("The natural Viagra®") and Licorice root  have a mild monoamine oxidase (MAO) inhibitory effect and may intensify the effects of anesthesia. (*note some well known and popular anti-depressants are MAO inhibitors, disclose any and all medications you are taking - your life may depend on it!)
• Melatonin decreases the amount of anesthesia needed for surgery.
• Echinacea may have a severe impact on the liver when general anesthesia is used. Please advise your surgeon of all medications and supplements and alert him to the possible effects of herbal supplements and remedies, he may not be aware of the contraindications.

Special Medication Alerts!

If you are on Anti-depressants, please advise your doctor. Some monoamine oxidase (MAO) inhibitors (also known as MAOI) intensify the effects of the anesthesia - especially General. This could be quite dangerous in the operating room if your doctor is unaware of your medication usage. If you advise your doctor he or she can make adjustments for your anesthesia or at least will watch for the slightest decrease in heart or breathing rate.

These medications may include: Isocarboxazid, Marplan, phenelzine (Nardil, Nardelzine)
tranylcypromine (Parnate, Sicoton), Deprenyl, selegiline hydrochloride, They are used for the treatment of depression, obsessive-compulsive disorder, eating disorders, essential hypertension (pargyline), chronic pain syndromes, and migraine headaches. They work by inhibiting nerve transmissions in brain that may cause depression. Tranylcypromine and phenelzine account for over 90% of all MAO inhibitors currently prescribed. 

It is reported that drug interactions can occur even weeks after discontinued use of an MAOI. Therefore, in patients undergoing General anesthesia, cessation of usage is normally instructed several weeks prior to surgery to avoid possible cardiovascular effects. Although, I know of several patients who never were instructed to cease their medications and were perfectly fine.

"Anesthetic Requirements: Anesthetic requirements are increased, reflecting accumulation of norepinephrine in the CNS." Ref: Stoelting, R.K, Pharmacology & Physiology in Anesthetic Practice, pp. 378-381.

In Conclusion
The above information is not meant to scare you but rather to inform you so that you are able to make a well-educated decision regarding your anesthesia choice. Remember, thousands of people undergo anesthesia safely every day. Please don't let anesthesia be the straw that broke the camel's back - just know that these complications are possible.

The Least You Need To Know

• As soon as your body is cut or manipulated - your body goes to work. Your heart rate quickens, your body starts to try and repair the injury with a vengence. Well, anesthesia blocks this reaction until after the surgery is over and keeps your body from trying to overwork itself intra-operatively (during surgery). 

• Anesthesia  also helps you forget about your surgery. Surgery can be very traumatic for some so why suffer, right? Healing is better and faster when one does not realize or remembers pain.

• Anesthesia works in 5 ways:

  1. analgesic (pain reliever)
  2. amnesiac (loss of memory)
  3. promotes unconsciousness
  4. immobility of the patient
  5. elimination (or reduction) of autonomic responses such as tachycardia (increased heartbeat), increased breathing, hypertension, lacrimation (tear production)

• The obstruction of sensory, reflex, mental and motor functions are needed to safely and effectively operate on a patient. 

• There are a few choices that you may have for anesthesia although not all surgeons and their practices will offer every one.

• The four main categories of anesthesia are:

  • local anesthesia
  • regional anesthesia 
  • sedation 
  • general anesthesia 

• General Anesthesia can be given by an inhaled gas or by a liquid. 

• Liquid Sedation can be given by injection or some even my oral medication.

• Choose a certified Anesthesiologist - especially when going under General. This may cost more to have a separate anesthesiologist but it is worth your life.

• To become an anesthesiologist, a person must complete:

  • college

  • medical school

  • internship

  • three-year anesthesiology residency

• There are some medications and supplements that you simply should not be consuming before and after going under anesthesia, although the above list may be a partial list PLEASE talk this over with your surgeon.

• KNOW THE RISKS!

• Do realize that thousands of patients safely go "under" every day and that these risks, although possible, are rare.

Online Anesthesia Textbooks (all links leading out of the site launch a new window)
Anaesthetic Pharmacology Textbook (UK)
Anaesthesiology Textbook
Pulmonary Artery Catheterisation
Vascular Thoracic Anaesthesia Manual
Intern On-call Handbook
Obstetric Anaesthesia
Virtual Library

Related Links (all links leading out of the site launch a new window)
American Society of Anesthesiologists
Journal of the American Society of Anesthesiologists
Anaesthesia On-Line - UK 
GASNet - An Online Anesthesia Network
Martindale's Health Science Guide: Anesthesiology & Surgery Center
Virtual Anaesthesia Textbook Home Page 

References:
Yale Medical Core Curriculum - Yale Medical University
Ovassapian A, Schrader SG. Fiberoptic-aided bronchial intubation. Sem Anesth 6:133-142, 1987.
Stoelting, R.K, Pharmacology & Physiology in Anesthetic Practice, pp. 378-381.
Merriam-Webster Medical Dictionary
J Bergsbaken, University of Wisconsin, Pulseless Electrical Activity"
Virtual Anesthesia Textbook
D. John Doyle MD PhD FRCPC Department of Anaesthesia, The Toronto Hospital
Diagrams, Henry Gray - Anatomy of the Human Body
American Academy of Pediatrics, The Transfer of Drugs and Other Chemicals Into Human Milk (RE9403) Pediatrics - Volume 93, Number 1 January, 1994, p 137-150

*drug interactions: "Induction dose requirements of DIPRIVAN may be reduced in patients with IM or IV premedication, particularly with narcotics (eg, morphine, meperidine, and fentanyl, etc) and combinations of opioids and sedatives (eg, benzodiazepines, barbiturates, chloral hydrate, droperidol, etc). These agents may increase the anesthetic effect of DIPRIVAN Injectable Emulsion and may also result in more pronounced decreases in systolic, diastolic, and mean arterial pressures and cardiac output. During maintenance, the rate of DIPRIVAN administration should be adjusted to the desired level of anesthesia and may be reduced in the presence of supplemental analgesic agents (eg, nitrous oxide or opioids). The concurrent administration of potent inhalational agents (eg, isoflurane, enflurane, and halothane) during maintenance with DIPRIVAN has not been extensively evaluated. These inhalational agents can also be expected to increase the anesthetic and cardiorespiratory effects of DIPRIVAN. DIPRIVAN does not cause a clinically significant change in onset, intensity, or duration of action of the commonly used neuromuscular blocking agents (eg, succinylcholine and nondepolarizing muscle relaxants). No significant adverse interactions with commonly used premedications or drugs used during anesthesia (including a range of muscle relaxants, inhalational agents, analgesic agents, and local anesthetic agents) have been observed when used in recommended dosages". http://www.diprivan.com