The Anesthesia Spectrum: Choosing the Right Anesthesia

What is Anesthesia?

Anesthesia refers to the use of certain drugs to prevent pain, sensation, awareness, or movement during a surgical procedure. It is an essential component of any surgical procedure and is aimed at making your surgical journey comfortable.

The type of anesthesia for you will depend on factors like the planned procedure, your previous medical conditions, previous surgeries, previous anesthetic exposures, history of allergies, your anesthesiologist’s choice and finally your choice. Your anesthesiologist will discuss all the possible anesthesia options in your case with you before your procedure.

Preoperative evaluation for Anesthesia

Some patients ask – How will my anesthesiologist decide the choice of anesthesia?

A good preoperative evaluation by a qualified and experienced anesthesiologist is very important for formulating an optimal plan of anesthesia which keeps the patient pain free and gives the surgeon good operating conditions while achieving risk reduction for both anesthesia and surgery. There are many criteria in preoperative evaluation that are considered by your anesthesiologist while deciding the anesthesia options for you. These include:

• History: First of all, your anesthesiologist will take a detailed medical and surgical history from you. You should mention all your medical conditions and the treatments being taken for those conditions. You should also mention all the surgeries that you have undergone, starting from oldest to latest. If you know about any anesthetic or surgical problems encountered in your previous procedures, you should mention them. It is also pertinent to mention any general allergies or allergies to any medicines that you are aware of. For example, if you are allergic to eggs, your anesthesiologist may want to avoid an anesthetic drug called propofol in your anesthesia.
• Physical examination: After history, a complete physical examination will be performed by your anesthesiologist to look for any physical findings that may need further assessment or medical management. For example, you may not have symptoms of asthma earlier, but your anesthesiologist may find a wheeze in your chest, suggestive of mild asthma and may prescribe you some inhalers.
• Investigations: A history and physical exam is followed by a review of all the relevant investigations. These may include blood tests, urine tests, Electrocardiogram (ECG), Chest X-ray and other tests specific to the surgery to be performed.
• Surgery being planned: Certain types of anesthesia may be feasible for some surgeries and may not be feasible for others. This limits the choice of anesthesia options that you may be offered. For example, spinal anesthesia is best suited to surgeries below the ribcage and cannot be used for surgery on the brain.
• Patient factors: Some patient factors may not be favorable for a particular type of anesthesia, even if it is the first choice for a procedure. In that case, the anesthesiologist may be inclined towards the second choice of choice of anesthesia. For example, coronary artery bypass surgery (CABG) involves cutting the chest open (thoracotomy), is a prolonged surgery and involves blood loss and blood transfusions. So it is best done under general anesthesia. But if the patient has severe COPD (a lung disease), the anesthesiologist may decide to go ahead with epidural anesthesia. This may not be the first choice for CABG, but is best for this patient as it spares the need for airway instrumentation and ventilation of the diseased lungs.
• Patient choice: Your anesthesiologist will discuss all the anesthesia options possible in your case for your specific surgery. You can indicate your choice from the possible options, but it is strongly recommended to go with the choice that your anesthesiologist considers best for you. This is what I would do, if I were the patient!

What are the types of anesthesia?

There are four main types of anesthesia:

• General anesthesia (GA)
• Regional anesthesia
• Monitored anesthesia care (MAC)
• Local anesthesia          

We will review each of the above-mentioned anesthesia options, one by one, along with their indications, benefits, and drawbacks.

General anesthesia (GA)

• General anesthesia (GA) is a type of anesthesia in which certain medicines are injected in your veins or certain gases are administered to you from a mask, to put you to sleep.
• You will fall asleep before the procedure starts and will remain unconscious throughout the procedure. You will have no pain or awareness during the procedure.
• After your procedure is over, your anesthesiologist will stop the anesthetic drugs and give some medicines to reverse the effect of anesthesia and wake you up.
• Since GA puts your brain to sleep, any surgery on any part of the body can be performed under GA. However, GA is usually reversed for surgeries above the umbilicus. It can also be used for surgeries below the umbilicus in cases where patient wants general anesthesia or there are contraindications to spinal anesthesia (please see Spinal Anesthesia (SA).
• For the patient, GA offers the advantages of no pain or awareness during the procedure and for the surgeon, GA offers a fully cooperative patient with excellent muscle relaxation.
• GA is very safe with low risk of complications in normal patients. However, in patients with concomitant medical conditions like high blood pressure, diabetes, asthma, epilepsy, heart disease, liver or kidney disease etc, the risk may be higher depending the age of patient, number and severity of medical conditions, planned surgery (major or minor), duration of surgery (short vs long duration) and history of any major allergic reaction to anesthetic drugs previously.
• The side effects with GA are few and most of them usually abate on their own or with simple medicines. For example, nausea and vomiting, sore throat, drowsiness or confusion on waking up, shivering, allergic reactions etc.
• For more information on general anesthesia, please see General Anesthesia (GA).

Regional anesthesia

• Regional anesthesia is a type of anesthesia in which anesthetic drugs are injected in specific regions of the body.
• This blocks the transmission of sensations in a single nerve or a group of nerves, causing temporary absence of pain, sensation and motor activity in the area supplied by the affected nerves and allowing surgeries to be performed in those areas.

Advantages of regional anesthesia over general anesthesia

• It offers distinct advantage over general anesthesia as it avoids airway instrumentation required for general anesthesia, with lesser chances of sore throat or chest infection.
• It avoids the effect of drugs on the whole body, thereby having lesser systemic side effects.
• The patient can remain awake during the procedure.
• Lesser incidence of nausea, vomiting, and other side effects associated with general anesthesia.
• Early return of oral intake and bowel function.
• Benefits of good muscle relaxation with lesser bleeding for the surgeon.
• Pain relief continues in the postoperative period, unlike general anesthesia where pain relief ends immediately when the patient wakes up.
• Avoids the risks of general anesthetic drugs in high-risk populations like in patients with chronic kidney disease, liver disease, hypertension, old age etc.
• Much more cost-effective as compared to general anesthesia.
• Quicker recovery and shorter hospital stay as compared to GA.
• Spinal anesthesia is the choice of anesthesia in cesarean section as all pregnant patients are considered full stomach and are high risk of aspiration in GA. Moreover, pregnant patients have varying degrees of airway edema and a more difficult airway as compared to general population.
• Moreover, epidural anesthesia serves as a very useful adjunct to spinal or general anesthesia in surgeries of upper abdomen, thorax (coronary artery bypass surgery), orthopedic surgeries of lower limbs, by providing continuous pain relief through epidural catheter. This helps the patient to breathe pain free, eat normally, get out of bed early, and do the physiotherapy exercises, thereby allowing early mobilization and early return to normal functions.

Following are the main types of regional anesthesia:

• Spinal Anesthesia (SA)
• Epidural anesthesia (EA)
• Combined spinal-epidural anesthesia (CSE)
• Caudal block
• Regional nerve blocks or Peripheral nerve blocks, including ring blocks

Neuraxial Anesthesia: The first four types of Regional Anesthesia – spinal, epidural, combined spinal-epidural, and caudal block are together categorized as Neuraxial Anesthesia as the local anesthetic is deposited in the center of the body near the spinal cord.

Regional nerve blocks or Peripheral nerve blocks: In the fifth type-regional nerve blocks, the local anesthetic is deposited around the peripheral nerves.

Spinal anesthesia (SA)

• Spinal anesthesia is a type of regional (neuraxial) anesthesia in which an injection is given in your lower back, to anesthetize your body below your umbilicus.
• The injection is given with a with a very fine needle, and it’s not painful at all. You will feel a little prick, just like a mosquito bite
• An anesthetic drug is injected through this needle into the cerebrospinal fluid (CSF). This is a colorless fluid that is present around your brain and spinal cord and the nerves to all parts of your body pass through this fluid. So when anesthetic drugs are injected in the CSF, the nerves get anesthetized.
• Soon after the injection, you will start feeling numbness, tingling, or warmth in your legs. After 3-5 minutes, your legs will become heavy and you won’t be able to lift them up.
• You may remain awake during the surgery or your anesthesiologist may administer you some drug to make you sleep through the procedure. This is a light sleep and you can easily be awakened from this sleep.
• Spinal anesthesia is most suited for surgeries below the umbilicus. These include lower abdominal, pelvic, rectal or lower limb surgeries. Surgeries above your ribcage are generally done under general anesthesia.
• Being a form of regional anesthesia, spinal anesthesia offers many benefits over GA. (see advantages of regional anesthesia above).
• Spinal anesthesia is extremely safe with a very low complication rate in experienced hands. Some patients complain of not being able to feel or move their legs or remaining awake during the surgery. Some others have persistent low backache or severe headache a few days after the surgery. Spinal anesthesia has also been associated with peripheral injuries, accidental hematoma formation around the nerves or infection. However, nowadays the complication rate is very low and should not deter anyone from opting for spinal anesthesia for surgeries below the umbilicus.
• For more information on spinal anesthesia, please see Spinal Anesthesia (SA).

Epidural Anesthesia (EA)

Epidural anesthesia is a form of regional (neuraxial) anesthesia and is very similar to spinal anesthesia, in that an anesthetic drug is given through a needle inserted in your back and you will start feeling numbness, warmth and weakness in your legs within a few minutes. However, there are a few differences between spinal and epidural anesthesia:

• The anesthetic drug is injected into a space in your back called the epidural space, instead of injecting the drug in the cerebrospinal fluid as in spinal anesthesia.
• The onset of effect if anesthesia is slower compared to spinal anesthesia.
• The incidence of side effects like fall in blood pressure is lesser as compared to spinal anesthesia.
• The needle used in epidural anesthesia is thicker than that used in spinal anesthesia. However, a numbing injection is given by your anesthesiologist with a very thin needle to numb your skin for placing the epidural needle. So you won’t feel any pain of the epidural needle.
• The epidural anesthesia usually involves placing a very thin plastic catheter in your epidural space through the epidural needle. The advantage of this catheter is that the anesthesiologist can repeat the anesthesia drugs in this catheter during the surgery, if the surgery gets prolonged, whereas it is not so with spinal anesthesia.
• Moreover, the epidural catheter can be used to provide continuous pain relief in the postoperative period for 24-48 hours or even more. This offers a distinct advantage over spinal anesthesia and is very useful in orthopedic surgeries allowing early mobilization and early physiotherapy.
• The epidural catheter is also used to for painless labor and delivery. In case there is any problem during normal delivery, the same epidural catheter can be used to administer drugs for anesthesia in cesarean section.
• Unlike spinal anesthesia, the use of epidural is not limited to surgeries below the umbilicus. The epidural can be given in higher spaces for surgeries on the thoracic level (chest).
• Epidural is also used to provide low back pain relief in cases of chronic low backache by injecting steroids and local anesthetics.

Monitored Anesthesia Care

This is a type of anesthesia in which you are administered anesthesia drugs by your anesthesiologist in carefully titrated doses, so that you remain awake during the procedure or go into a light sleep, while breathing on your own and maintaining your airway.

MAC is preferred in short procedures, done on a day care basis. During the procedure, your anesthesia provider monitors your conscious levels, your vital functions (like heart rate, blood pressure, respiration, oxygenation), and any abnormal clinical situations and acts to rectify them.

Sometimes, your anesthesia provider may convert MAC to general anesthesia, if you or your surgeon are uncomfortable during the procedure under MAC. So the preparation and preoperative evaluation for MAC is the same as GA.

MAC offers the advantages of a quicker recovery and quicker discharge from the hospital, with a much lesser side effect profile, as compared to GA.

For more information on MOC, please read Monitored Anesthesia Care (MAC).

Local Anesthesia

What is local anesthesia?

Local anesthesia is a type of anesthesia in which certain numbing drugs are either injected with a needle or applied as creams/sprays, in specific areas of the body, to perform minor procedures in that particular area.

It is the preferred technique for minor procedures of short duration, on small areas of the body. If it is a major procedure or involves a larger area or is likely to last longer, then some other form of anesthesia may be more appropriate.

Local anesthesia is used for which procedures?

• Local anesthesia is used for many procedures which are routinely done in the doctor’s office or the emergency department, like for applying stiches, draining pus, obtaining a biopsy, mole removal, nail removal, dental procedures etc.
• Local anesthesia may also be used by a surgeon to provide immediate pain relief in the operated area till the other pain killers kick in. For example, the incisions on abdomen after a laparoscopic surgery are commonly injected with local anesthetic at the end of surgery to provide additional pain relief.
• Local anesthesia is often used by anesthesiologists to numb the skin of an area with a very fine needle, so that larger needles inserted in that area do not cause pain. For example, before putting a wide bore needle in your vein, before giving epidural anesthesia (epidural needle is thick) and sometimes, even before spinal anesthesia especially in obese patients where multiple attempts may be needed to put a spinal.

How does local anesthesia feel?

You will remain awake during the procedure and the only pain that you will feel is the pain of needle used for injecting the local anesthetic drug. The part of the body anesthetized will feel numb and heavy. It recovers after some time, usually 1-2 hours. If due sterile precautions are followed, there are no significant complications of local anesthesia. In the absence of any other considerations, you should be able to go home after 1-2 hours of observation after your procedure.

Sometimes, you may not initially feel pain but you may start feeling pain later, as the surgeon goes into the deeper tissue. This is usually because the deeper tissue may not be adequately anesthetized. In that case, you can request your doctor to administer additional local anesthetic.

Which drugs are used for local anesthesia?

Following are the main drugs routinely used for local anesthesia:

• The most common drug used to administer local anesthesia is lidocaine. It is an excellent pain relieving drug with quick onset and short duration of action.
• Other drugs with longer duration of action are bupivacaine and ropivacaine.

The exact drug and the dosage/strength of drug will be decided by your anesthesiologist or surgeon administering the drug.

Carry home message

Anesthesia is an important and inseparable part of any surgery. It is aimed at keeping you pain free and comfortable throughout your procedure. There are many types of anesthesia options available, each with some benefits and drawbacks. Your anesthesiologist will do a Preanesthetic checkup before your procedure by taking a detailed history, doing a thorough physical examination and reviewing your investigations. Based on the preanesthetic checkup findings and keeping in view your planned surgery, your anesthesia provider will explain all the anesthesia options feasible in your procedure and finally make an anesthesia plan after discussing with you and considering your choice as well. Nowadays with newer drugs and techniques, anesthesia is extremely safe, with low incidence of side effects or complications. Talk to your anesthesia provider and understand your anesthesia options well. Have a nice and pain free surgery. Stay healthy!

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