Common Questions and Insights about Anesthesia
Will I need General Anesthesia for my Surgical Procedure?
Article Written By: Dr. Taylor J. Graber MD
Peer Reviewed By: Dr. Shane Regnier MD, PhD
Date Updated: July 11th, 2022
Undergoing a surgical procedure? Have questions about Anesthesiology? ASAP IVs has you covered by answering some of your burning questions about how the process works!
1. What's the difference between general anesthesia and local anesthesia? What about sedation? What does anesthesia do?
Local anesthesia and general anesthesia are two very different procedures.
Local anesthesia is the administration of local anesthetics, which are medications administered for the purpose of interrupting neural conduction. They function by inhibiting the influx of sodium ions in neuronal membranes, which prevents the neuron from “firing” or depolarizing. This prevents the cell from transmitting an electrical signal, which prevents a message from being delivered down the nerve to the spinal cord and then to the brain. Functionally, this results in “anesthesia” or an absence of sensation at the location where the medication has been injected. This can be a “field administration” where the local anesthetic (numbing medicine, such as Novacaine, Lidocaine, Ropivicaine, Bupivicaine, Cocaine, etc.) is administered broadly to a specified area. This can be helpful when there is a skin laceration, and numbing the area would make the administration of stiches more comfortable to the patient. As an alternative, the local anesthetic can also be administered in an extremely localized and targeted fashion. This is when a dentist administers the local anesthetic to certain areas of the mouth, right next to specified nerves, which makes the mouth completely insensate. Physicians can also use this anatomy for various other procedures, such as targeted nerve blocks. Ultrasound can be used to obtain a real-time picture of a nerve and patient anatomy, and a needle can be carefully inserted directly adjacent to a nerve to very effectively “numb” a desired part of the body. This can be seen in Interscalene Nerve Blocks, Femoral Nerve blocks, Sciatic Nerve blocks, etc. Local anesthetics can also be used for spinal or epidural anesthesia for effective pain control during labor and the delivery of a baby, which is very safe and well-tolerated.
On the other hand, sedation and general anesthesia work in a very different way. Whereas local anesthetics act on targeted nerves, sedation and general anesthesia work on the brain and brainstem/spinal cord. This is achieved through the use of targeted intravenous or inhaled medications to obtain a desired effect. These medications disrupt electrical impulses and neurotransmitters in the brain to alter normal brain physiology and induce a state of unconsciousness. The amount of medication given can be used to “deepen” the level of sedation, and make the patient less aware or less awake. This occurs in defined “stages” or “levels of procedural sedation” with the deepest level of anesthesia being referred to as General Anesthesia.
1: Least Sedation – Minimal Sedation/Anxiolysis – This is the lightest plane of anesthesia, where a medication is given to “take the edge off” but the patient is still breathing effectively and can adequately respond to questions or verbal sedation.
2: Moderate Sedation or Conscious Sedation – This represents a deeper level of sedation, which results from more medications or larger doses of medications being given. The patient is more “sleepy” than in Minimal Sedation, but upper airway muscle tone and airway reflexes are diminished, which can lead to obstruction or snoring. Once sedation reaches this phase, it is increasingly imperative for the patient to have monitors in place to measure physiologic functions (effective heart rate, rhythm, blood pressure, oxygen saturation), and that the provider is able to monitor the patient and act accordingly if there is instability in any of these monitors.
3: Deep Sedation – This represents a further deepening of the plane of anesthesia, where the patient can be aroused to more direct or noxious stimuli, but it may take multiple attempts to arouse the patient. Blood pressure, heart rate, oxygen saturation, and upper airway tone can be affected, so there should be a medical provider (most frequently an Anesthesiologist or Certified Registered Nurse Anesthetist) present to monitor the patient. This is a deeper plane of anesthesia than Moderate Sedation.
4: General Anesthesia – This represents the deepest plane of anesthesia. The patient is completely non-responsive to stimulation. The patient is often “unable to maintain an airway” which means they either stop breathing entirely or that obstructive sleep apnea becomes so severe that the patient is unable to breathe in and out with unconscious breaths. Heart rate and blood pressure may be effected. The medical provider should be able to predict and act extremely quickly if medications are needed to rescue heart rate and blood pressure, or if a the patient needs to have a breathing tube inserted into the trachea to sufficiently restore effective breathing.
2. Is anesthesia considered safe for most people? Can it cause any complications or side effects?
General anesthesia for surgical procedures has advanced rapidly over the last century. With the advent of increasingly sophisticated intraoperative monitors, physician anesthesiologists or CRNAs are able to more effectively monitor patients under anesthesia and make changes quickly when they are needed. Due to the increased knowledge base of these skilled providers, and the vastly improved technology, general anesthesia is exceedingly safe.
The most frequent side effect of general anesthesia is nausea and vomiting following the procedure. This is from a combination of factors, including the type of surgery performed, the medications used for the anesthesia, the amount of narcotics given, and others. Patients who experience nausea with anesthesia (called Postoperative Nausea and Vomiting or PONV) are more likely to experience it with future surgeries. The risk factors for PONV are: being young, a female, have a history of PONV or motion sickness, a non-smoker, having a laparoscopic, breast, or ENT procedure, or long hours of using inhaled anesthetics or nitrous oxide. The risk of developing PONV in the postoperative period can be attenuated by the Anesthesiologist by administering pre-emptive anti-emetic (anti-nausea) medications (such as a Scopolamine patch, Dexamethasone (a steroid), Metoclopramide, Ondansetron, Droperidol), using a total intravenous anesthesia mixture (called TIVA, mainly using Propofol as the sole anesthetic), using regional anesthesia procures where possible (using targeted nerve blocks to reduce the pain experienced during and after the surgical procedure, which minimizes the amount of opioid or narcotic medications which need to be administered, which predispose a patient to increased nausea).
After PONV, the next most frequent post-operative side effect is delayed mental status or neurologic recovery. Most patients will feel sleepy after anesthesia, and the depth of sedation used in the anesthetic, as well as the medications used and techniques applied, can influence how long it takes to recover after anesthesia until a patient is mentally alert and back to baseline. The age of the patient and whether the patient has pre-existing dementia can also effect the wakening after anesthesia. This information is used by the Anesthesiologist to tailor the anesthetic to each individual patient to optimize results.
Other side effects include surgical pain (which can be reduced by the use of local anesthetics or targeted nerve blocks during the surgery, as well as the administration of intravenous or oral pain medications), a sore throat from the breathing tube (the endotracheal tube is gently inserted through the mouth, through the vocal cords, and into the trachea. This is frequently a gentle, and controlled process, however this can cause a sore throat after the procedure), urinary retention, and a few others.
Overall, general anesthesia is very safe and incredibly well-tolerated.
3. When might you get anesthesia? (Type of procedure, etc.) Why is it necessary?
Sedation is given for any medical procedure where pain or anxiety may place the patient at risk or may make the medical procedure not safe to perform.
Local anesthetics can be used for removal of skin lesions, suturing skin lacerations, or minor surgical procedures.
Light sedation can be used for office based procedures which are not very painful, often in tandem with local anesthetics to reduce the amount of pain a patient perceives.
Moderate to General Anesthesia procedures are reserved for more invasive procedures and surgeries, such as colonoscopies, appendectomies, cholecystectomies (removing the gallbladder), total knee replacements, open heart surgeries, etc.
The more surgical stimulating a procedure is, the more anesthesia is generally needed to keep a patient still, unconscious, and comfortable during a procedure. By using local anesthetics, spinal injections, or regional nerve blocks, the amount of pain perceived by a patient can be reduced, and the amount of sedation or anesthesia needed to keep a patient comfortable can be reduced, leading to reduced nausea, faster neurologic recovery after sedation, faster time to leave the hospital/surgery center and return home, and improved satisfaction.
4. Who performs this procedure?
Light sedation may be performed by nurses who are supervised by a physician (such as a Gastroenterologist, Interventional Radiologist, Cardiologist).
Moderate sedation to General Anesthesia is reserved for medical professionals who are trained in the use of anesthesia medications. To a limited extent, these can be physicians in the Emergency Department (such as the use of Midazolam or Etomidate before a cardioversion, or the use of Ketamine before treating a shoulder dislocation), but these deeper levels of anesthesia are usually reserved to a physician Anesthesiologist or a certified registered nurse anesthetist (CRNA) who may or may not be working in conjunction with an Anesthesiologist.
Before any surgical procedure, it is important to note who your medical care team is, as well as their roles and responsibilities, to make sure any procedure is done safely and effectively.
5. Does it commonly involve side effects? Are most of these major or minor? How long do they last? Please list some common side effects, with a brief description for each wherever necessary
The most common side effect of general anesthesia is postoperative nausea and vomiting or PONV, which can effect 30% of the general population who undergoes a surgical procedure. This is a minor side effect, but can be majorly uncomfortable or inconvenient if you are the patient. The amount of time PONV last is often very short, and is effectively treated in the post-operative care unit (PACU) with the use of anti-emetic (anti-nausea) medciatons.
6. List potential complications of anesthesia (we're looking for major complications here, not short-term side effects). Do these complications happen because of the anesthesia, or more due to underlying conditions?
Most complications of anesthesia arise from the underlying medical status or health problems of the patient. If a patient has a history of PONV, they are more likely to have PONV with recurrent surgeries (as high as 80% of the time with anesthesia, unless effectively prevented). If a patient has a history of Type 2 Diabetes, Obesity, Congestive Heart Failure, and Coronary Artery Disease and is undergoing an open heart surgery, they are more likely to experience complications related to cardiopulmonary instability (maintaining a normal heart rate, blood pressure, oxygen saturation, and ventilation). The complications which will largely depend on a patient’s medical status and general condition.
There are other complications which can arise, such as aspiration of food or liquid into the lungs with the start (induction) of general anesthesia. The odds of this happening are extremely low due to normal pre-operative fasting guidelines, which state that you should not have solid food for >8 hours and should avoid liquids for >2-4 hours before surgery starts. The less food or liquid which is in the stomach, the less the risk of aspiration. For these reasons, it is important to obey fasting guidelines which are provided to patients prior to surgery or caesarian sections.
Possible complications can include the following:
Nausea and vomiting (PONV)
Sore throat, Damage to teeth, or Lacerations (cuts) to the lips, tongue, gums, throat from the insertion of the Endotracheal Tube (aka breathing tube)
Nerve injury secondary to body positioning
Awareness under anesthesia
Anaphylaxis or allergic reaction
Malignant hyperthermia (high fevers, metabolic acidosis, and hemodynamic instability with general anesthesia)
Aspiration pneumonitis (the regurgitation of stomach contents into the lungs).
Respiratory depression
Stroke
Hypoxic brain injury
Embolic event
Cardiovascular collapse, cardiac arrest
Death
7. What about awareness while under anesthesia -- how is that altered and is that a common complication?
Awareness under anesthesia is incredibly rare. The rate at which it occurs in the general anesthesia population is 1 case out of every 1000 cases of general anesthesia. This can occur most commonly under emergency cases (where altered doses of anesthesia have to be provided so that hemodynamic stability is maintained and the patient stays alive), obstetric cases such as an emergency caesarian section requiring an breathing tube (the amount of anesthesia being administered needs to be adjusted because too much anesthetic can make the uterus relaxed and boggy leading to peripartum hemorrhage or severe bleeding), or cardiac (open heart) cases (where anesthesia can affect hemodynamics requiring adjustment, and where the patient is placed on a cardiac bypass machine with its own anesthesia conduit). The rates of these are extremely low, and the job of the anesthesia provider is to carefully monitor the patient and doses of medications being given to most adequately prevent awareness from developing.
8. Please bullet list any factors that increase your risk of anesthesia side effects or complications (like any underlying conditions).
Nausea and vomiting (PONV)
Risk Factors: Young, Female, Non-Smoker, History of PONV, Surgical Procedure which is Breast/Laparoscopic/ENT, long duration of inhaled anesthetics or nitrous oxide, copious use of narcotics or severe postoperative pain
Sore throat, Damage to teeth, or Lacerations (cuts) to the lips, tongue, gums, throat from the insertion of the Endotracheal Tube (aka breathing tube)
Risk Factors: Altered anatomy of the oropharynx, small mouth opening, large tongue, history of being difficult to intubate, previous cancer or malignancy of the oropharynx requiring radiation, history of prolonged intubation requiring tracheostomy.
Nerve injury secondary to body positioning
Risk Factors: History of pre-existing nerve deficits, extremes of body habitus (obese or extremely skinny/underweight), type of surgery being performed.
Awareness under anesthesia
Risk Factors: Emergency surgery, Emergency Caesarian Section, Heart Surgery
Anaphylaxis or allergic reaction
Risk Factors: History of allergies to medications or latex, previous history of allergic reactions
Malignant hyperthermia
Risk Factors: History of previous malignant hyperthermia or family member with history of malignant hyperthermia, history of rhabdomyolysis
Aspiration pneumonitis (the regurgitation of stomach contents into the lungs).
Risk Factors: Emergency surgery, starting general anesthesia where the patient is not fully fasted, history of gastric outlet syndrome or impaired gastric motility or impaired esophageal sphincter function
Respiratory depression
Risk Factors: obesity, use of preoperative narcotics, history of obstructive sleep apnea, not being attended to by an anesthesia professional (Anesthesiologist MD or DO, or CRNA)
Stroke, Embolic Event, or Hypoxic Brain Injury/ Cardiovascular collapse, cardiac arrest/ Death
All extremely rare. More common when the patient is undergoing a high risk emergency surgery or the patient has multiple critical medical comorbidities.
9. Can you reduce your risk of experiencing anesthesia side effects? If so, offer some basic tips for how.
For most surgical procedures there is nothing which needs to be done other than following the hospital or surgery center’s instructions (such as fasting, making sure you have a driver to pick you up, making sure you have a caretaker for the remainder of the day of surgery). These guidelines are created for a reason, to make sure that everything goes smoothly, risk factors are mitigated, and everyone is safe performing the indicated procedure.
If you have multiple medical comorbidities, make sure that you follow up with your primary care physician prior to surgery to make sure that they are appropriately under control. Blood pressure medications may need adjusting. Anticoagulants or blood thinners may need to be stopped. The chest pressure you have been experiencing when walking up stairs may be a sign of heart ischemia requiring a workup prior to surgery.
10. Do you recommend talking to your care team and anesthesiologist if you have any concerns or questions about the procedure/side effects of anesthesia? If so, why/how might that help?
It is always important to be your own best healthcare advocate. You should take an active participant role in the medical decisions affecting your health, because you are the one who will live with the consequences, not the doctor or nurse. You should take the time to learn about your medical issues being treated, and learn how to best reduce their complication rates.
This includes having sedation or anesthesia for a surgical procedure. Based on the surgery being performed, you are fully entitled to ask what the plan is for anesthesia (sedation vs. general anesthesia), if you as the patient have any risk factors for complications, and if so, how these are going to be monitored or prevented. You are your best advocate to ask if alternate anesthesia approaches can be attempted, such as the use of nerve blocks or regional anesthesia techniques to reduce intraoperative and post-postoperative pain.
In general, if you have any questions or concerns, feel free to voice them and ask questions to your care team. You are the patient, and the most important part of any surgical procedure.