What happens if you are allergic to the anesthesia drugs you receive? 

This is one of the most common questions my colleagues and I are asked. 

Allergy denotes a response by the body's immune system to a `foreign` substance. Usually the substance (or `allergen`) is something not ordinarily harmful to the body, such as penicillin. 

Severe allergic reactions during anesthesia are fortunately rare, occurring only once in every 5,000 to 25,000 anesthetics. Unfortunately, these reactions can sometimes be fatal; about a 3% (3 in 100) mortality has been documented. 

The most severe form of allergic reaction is known as anaphylaxis. During an anaphylactic reaction the patient may experience difficulty breathing, as air passages close up. Swelling of the face and mouth can occur, and a reddish skin rash is also sometimes seen. The heart and blood vessels are severely affected, and this is the hallmark of the condition: the heart rate increases and blood pressure can drop to dangerously low levels. 

Anaphylaxis during general (asleep) anesthesia presents in a similar way but there are three unique features. 

First, the patient who is asleep cannot tell us about light-headedness or breathlessness which might be early warning symptoms. 

Second, during a typical general anesthetic, many drugs are given, and it is hardly ever clear which of these drugs have caused the reaction. 

Third, during anesthesia there are many other potential causes for the blood pressure to drop or the air passages to close off. A diagnosis of anaphylaxis is therefore not always easy to establish. 

Although severe allergic reactions may be a little more difficult to detect under anesthesia, a patient having an anaphylactic reaction under anesthesia is actually in a very good place to get promptly treated. All the necessary equipment and medication to successfully treat the reaction is at hand in the operating room. Anesthesiologists are experts in the treatment of such reactions. Treatment may include insertion of a breathing tube, administration of intravenous fluids, and a variety of drugs, the most important of which is epinephrine (adrenaline). Early and appropriate treatment is almost always successful. 

It is worth noting that drugs are not the only cause of allergic reactions. For example, one important non-drug cause of anaphylaxis is allergy to natural rubber (`latex`). Reactions to latex are a special problem during anesthesia as surgical gloves are usually made of this material. 

Two final notes about allergy. First, many allergic reactions are not life-threatening, resulting only in a transient skin rash or such symptoms as nausea and vomiting. Secondly, many drug reactions are not true allergies, representing only an increased sensitivity to common side-effects of the medication. 

Does diprivan, halothane or succinylcholine inhibit the body`s ability to regenerate heat? 

Your body temperature is normally tightly controlled around a set point near 37 degrees centrigrade. Anesthetic agents (e.g. halothane, Diprivan) affect body temperature in one of two ways. 

• First, they affect the body's thermostat, which is in the hypothalamus, a part of the brain. The effect of anesthetics is to widen the range of temperature that the hypothalamus allows. 
• Second, anesthetics cause vasodilatation (widening of blood vessels) which causes heat to be redistributed from the "core" to the surface. Vasodilation causes a net heat loss from the body, and a decrease in core body temperature. The hypothalamus allows this drop in temperature. 

Succinylcholine is a muscle relaxant that does not affect heat balance. However all muscle relaxants inhibit shivering, which is one of the compensatory mechanisms that your body uses when it becomes cold. Shivering generates heat through muscle contraction. 

Various warming measures are used before, during and after anesthesia to try to maintain body temperature at or above 36 degrees centigrade. These include keeping the operating room as warm as tolerable, forced air warming blankets, warmed intravenous fluids, and so on. 

Is there a maximum dose recommendation for versed? 

Not that I'm aware of. Versed, like most other anesthetic agents, is titrated to effect. In other words, you give some, as you assess the effect clinically and with monitoring equipment. Then you give some more if necessary. 

What is the name of a common anesthesia drug often administered along with Versed? Propinol? Proplyn? Propol? 

The drug you are thinking of is called propofol, originally introduced into the US by the company Zeneca, and marketed as Diprivan. Versed is one of the trade names for midazolam. 

Help!! Can you tell me why neostigmine would be contraindicated for the reversal of neuromuscular blockade in multiple sclerosis patients? 

ﾠAs you are aware, neostigmine is a drug used to reverse the effects of certain neuromuscular blocking agents that are commonly given during general anesthesia. Multiple sclerosis is a neurologic disease with a wide variety of signs and symptoms. I am not aware of any contraindication to the use of neostigmine that is specific to patients with multiple sclerosis. I would be interested to know where you obtained this information! 

I am allergic to ophthalmic neosynephrine. Do I need to worry about administration of this drug systemically? I believe it is used to increase blood pressure in emergency situations; might it be administered to me when I can`t advise of this allergy? 

Neosynephrine, also known as phenylephrine, is a drug that is commonly given by intravenous injection to treat low blood pressure during anesthesia. Phenylephrine eye drops are also widely used by ophthalmologists to dilate the pupil of the eye. 

Allergic reactions to phenylephrine eye drops can occur occasionally. These reactions can take the form of eye redness, swelling of the eyelids, redness of the skin around the eyes, and itching. This type of allergic reaction is called "contact dermatitis". 

Allergic reactions to intravenous phenylephrine are extremely rare. In someone who has a history of phenylephrine-related contact dermatitis, it may be impossible to predict whether a more serious, life-threatening allergic reaction (also called "anaphylaxis") might occur following the intravenous administration of phenylephrine. Allergists are the physicians best-trained to make an assessment of this problem and to perform further testing where appropriate. 

Your anesthesiologist should always be informed about your medication allergies or other adverse reactions to drugs. He or she will want to know the exact nature of the reaction you had, and the details of any allergy testing that may have been performed. With this information, the anesthesiologist is in a good position to make a judgement about avoiding the use of phenylephrine during your anesthetic. 

Any patient with a significant allergy is advised to carry this information at all times. Medic-Alert bracelets are useful - these are engraved with allergy or other health information helpful in case of a medical emergency. 

I am taking MS-Contin under a doctors care for chronic pain. Does this medicine interfere with novacain used in a dentist's office for a filling? If so what does a dentist use to numb the patients mouth? 

ﾠMS-Contin is a long-acting form of morphine, taken by mouth, which is often used for chronic pain conditions. 

Novocain is the trade name for the local anesthetic procaine. Procaine was one of the first local anesthetics developed, and the trade name has become synonymous with local anesthetics in general. 

Novocain, and other commonly used local anesthetics do not interfere with morphine. Pain killers may of course help to dull any dental pain that occurs after the dentist is done. You are unlikely to have a problem relating to your use of MS-Contin at the dentist`s office. 

What is morphine made from? 

ﾠMorphine is extracted from the dried milky exudate of the unripe seed capsule of the opium poppy (Papaver somniferum).