“What Is Anesthesia?” is one of the most frequently asked questions in a hospital environment. Put in the simplest way, anesthesia is the set of methods applied to perform a surgical or medical procedure painlessly and with patient comfort. Moreover, these methods not only eliminate pain; sometimes they cause loss of consciousness during the procedure (for example, general anesthesia) or only numb a certain area (for example, regional or local anesthesia), creating different effects.
What Is Anesthesia and How Does It Work?
The word “anesthesia” etymologically means “numbness” or “lack of sensation”; medically, it is an application that temporarily removes or suppresses sensations such as pain, touch, and temperature. The drugs used to block pain during surgery are called “anesthetics,” and they work by stopping or reducing signal transmission in certain parts of the nervous system. In some types of anesthesia (for instance, general anesthesia), a sleep-like state is created in specific areas of the brain, while in others (for instance, local or regional anesthesia), only nerve fibers are blocked and the patient’s consciousness remains intact.
You can think of this mechanism like turning down the volume of a music system. Normally, nerves in the body provide continuous data flow to the brain. This “data” is actually in the form of electrical impulses, similar to sound waves rising from a music recording. When anesthetic drugs are administered, this data flow decreases or is completely cut off. Various receptors and ion channels in nerve cells (especially sodium channels and GABA receptors) are targets for anesthesia. For example, propofol, one of the general anesthetic drugs, enhances the effect of an inhibitory system called GABA, thereby slowing neuronal activity and causing loss of consciousness. Local anesthetics, on the other hand, block sodium channels in the membranes of nerve cells, preventing the transmission of pain signals to the brain.
The body or the brain does not “shut down” entirely; rather, there is a temporary “mute” state affecting the brain, the senses, or both. After anesthesia wears off, the drugs are eliminated from the body and everything returns to normal. For this reason, anesthesia is a “reversible” condition. The doses of anesthetics and the type chosen are determined by considering both the scope of the surgery and the patient’s overall health status.
What Are the Main Types of Anesthesia Used Today?
In modern medicine, the primary types of anesthesia used in surgeries or diagnostic procedures can be grouped under a few main headings:
General Anesthesia: Affects the entire body and causes temporary loss of consciousness. It completely prevents feeling pain during surgery and generally ensures that the person does not remember the procedure. It is frequently used in large and long surgeries (e.g., heart and brain operations).
Regional Anesthesia: Methods that block the transmission of pain by numbing the nerve bundles in a particular area of the body. Spinal and epidural anesthesia fall into this category. They are often applied in lower abdominal and leg surgeries, as well as during childbirth (for pain control in cesarean or normal delivery).
Local Anesthesia: Used to numb a very small area of the body. For instance, for dental fillings or removal of small skin lesions, pain is eliminated only in the relevant area via injection or superficial (topical) drug application.
Sedation: Aims to keep the patient calmer and more comfortable. Usually, consciousness is not completely closed off, but the patient relaxes and may become semi-sleepy. It is often used for short to moderate painful procedures or for diagnostic procedures such as endoscopy and colonoscopy.
Monitored Anesthesia Care (MAC): An approach in which sedation and analgesia (pain control) are provided simultaneously, and the patient is monitored meticulously. Typically, the patient continues to breathe on their own; deeper sedation or analgesia can be added if necessary. It is preferred especially for minor surgical procedures or endoscopic interventions.
How Does General Anesthesia Induce Loss of Consciousness?
General anesthesia places the patient in a state similar to deep sleep but different from natural sleep. One might describe this as a “reversible coma.” The core principle involves reducing or interrupting communication among brain cells. For instance, propofol and similar drugs act on GABA receptors to enhance the “braking mechanism” of neurons. When the electrical activity in critical areas of the brain slows sufficiently, the person no longer responds to external stimuli. As long as appropriate doses are maintained, the patient remains in a “deep sleep” state throughout the surgery.
An additional important component is the deactivation of pain perception. In some general anesthesia protocols, muscle relaxants are also added so that the surgical field can be more easily visualized and involuntary muscle movements are prevented.
In general anesthesia, the nervous system does not completely “shut down”; the brain stem that controls vital functions continues to operate. Anesthesia specialists monitor the patient using various devices to ensure adequate breathing, circulation, and other reflexes. When mechanical ventilation (intubation) is needed, it is provided. At the end of the procedure, reducing or stopping the drugs gradually increases brain activity, and the patient slowly awakens. Typically, the person does not remember any part of the surgery and experiences minimal pain.
What Are the Risks Associated with General Anesthesia?
Although general anesthesia has become extremely safe, it still carries some risks, like any medical intervention. These risks are related to the patient’s age, underlying health conditions (such as heart, lung, or kidney problems), the duration and scope of the surgery, the properties of the drugs used, and the patient’s overall physiological status. Here are some of the main risks and complications that may be associated with general anesthesia:
Respiratory Problems: During anesthesia, respiratory reflexes are suppressed. Particularly in lengthy surgeries, lack of full lung expansion can result in “atelectasis” (collapse of a portion of the lung). The risk is somewhat higher in overweight individuals, smokers, or those with chronic lung disease.
Cardiovascular Issues: Sudden drops or rises in blood pressure, heart rhythm disturbances (arrhythmias), and, rarely, heart attacks may occur. Typically, conducting the necessary preoperative tests minimizes these risks.
Allergic Reactions: Some patients may develop an allergic reaction (skin rashes, breathing difficulties, anaphylactic shock) to the anesthetic drugs or other substances used (for example, latex gloves). Therefore, a detailed evaluation by the anesthesiologist before surgery is crucial.
Nausea and Vomiting: Quite common after general anesthesia, especially in the first hours and on the day following surgery. Various medications can be used to manage this.
Postoperative Delirium or Confusion: Particularly in older patients or those who undergo very long surgeries, temporary mental confusion or disorientation (trouble recognizing location, time) may appear.
Rare Severe Complications: Malignant hyperthermia (a rapid and uncontrolled rise in body temperature and muscle rigidity), stroke, or even death (though extremely rare) may occur. These risks are quite uncommon and are typically linked to underlying serious conditions or genetic predispositions.
Minimizing these risks depends on a thorough evaluation before surgery and professional monitoring during the procedure. Hence, patient safety is paramount in modern anesthesia practices. With advanced technology, monitoring equipment allows more precise adjustment of drug dosages, significantly lowering complication rates.
When Is Regional Anesthesia Preferred Instead of General Anesthesia?
In certain surgical procedures, general anesthesia may pose unnecessary risks or create additional problems in terms of undesirable side effects. In such situations, “regional anesthesia” is preferred. In regional anesthesia, nerve transmission is blocked in the area where the operation will be performed, so the patient does not feel pain but remains conscious (or can be lightly sedated if desired). When is regional anesthesia particularly advantageous?
Cesarean and Normal Delivery: Airway-related risks can be higher in pregnant patients, making spinal or epidural anesthesia a safer option. Moreover, the mother remains conscious, can witness the baby’s birth, and recovers more quickly.
Lower Extremity and Hip Surgeries: In hip fractures, knee replacements, or ankle operations, spinal or epidural anesthesia can completely numb that region. Thus, the operation can be performed without general anesthesia. This approach also eases postoperative pain control.
Patients with Higher Risk (Obesity, Respiratory Problems, etc.): Securing the airway in severely overweight individuals or those with significant respiratory illness can be challenging. Since regional anesthesia does not require airway manipulation, it offers an advantage for these patients.
Cardiac Risk Patients: General anesthesia can place a heavier load on the heart for some heart patients. Regional anesthesia can reduce the fluctuations in the cardiovascular system during the operation.
Short or Superficial Surgeries: Minor orthopedic procedures, certain vascular surgeries, or surgeries involving subcutaneous tissues can often be done more comfortably and quickly with regional blocks.
Another benefit of regional anesthesia is that numbness in the area often continues post-surgery, aiding in pain control. Thus, patients require fewer strong pain medications like opioids. However, regional anesthesia is not suitable for every procedure; for example, in large-scale abdominal or internal surgeries, general anesthesia may be unavoidable.
What Are the Differences Between Spinal and Epidural Anesthesia?
The two most well-known methods of regional anesthesia are spinal and epidural anesthesia. Both are administered in the lumbar region, numbing the lower body. However, there are key differences:
Application Site:
Spinal Anesthesia: A thin needle is used to enter the “subarachnoid space” in the lumbar region, injecting the drug directly into the cerebrospinal fluid (CSF). As a result, the nerve roots are directly numbed.
Epidural Anesthesia: A needle or catheter is placed into the “epidural space,” the area outside the membrane covering the spinal cord. The medication spreads through this space to achieve nerve blockage.
Duration and Intensity of Effect:
Spinal Anesthesia: Typically provides a very rapid (within 5–10 minutes) and strong anesthesia. In other words, almost the entire lower body becomes numb, including a noticeable loss of motor function. The effect lasts 1–4 hours, depending on the local anesthetic used.
Epidural Anesthesia: Has a slower onset (15–30 minutes) and may not be as strong as spinal anesthesia; however, the dose and spread can be better adjusted. If an epidural catheter is placed, the medication can be repeated or continuously infused, extending its duration.
Use Cases:
Spinal Anesthesia: Ideal for short lower abdominal and leg surgeries that can be completed with a single dose of medication, such as cesarean sections.
Epidural Anesthesia: Used when longer-term pain control is needed (for example, during normal labor for pain control or long orthopedic surgeries). With an inserted catheter, painkillers can also be administered post-surgery.
Side Effects:
Spinal anesthesia can cause a “spinal headache,” in which CSF leaks through the needle hole, leading to a severe headache that worsens or improves with position.
The risk of this is much lower with epidural anesthesia because it does not involve direct entry into the CSF. However, careful placement and removal of the catheter are required.
In summary, spinal anesthesia is a fast and effective choice, whereas epidural anesthesia offers longer-lasting and more adjustable comfort. Factors such as the surgery duration, the patient’s condition, and pain control requirements determine which method is suitable.
How Is Local Anesthesia Applied in Minor Procedures?
Let’s say you are getting a dental filling or having a small skin mole removed. In such cases, there is no need to numb the entire body or a large area. “Local anesthesia” is ideal for this type of small-scale procedure. Local anesthesia is applied to prevent pain transmission in a particular, limited region.
Methods of Application:
Injection: The most common method. For instance, for dental procedures, your dentist injects the drug into the gum or palate to numb that area. The same method is used for small skin lesions or minor surgical incisions.
Topical (Surface) Application: There are also creams, sprays, or gels that can be applied to the surface of the skin or mucosa. For example, “EMLA cream” used before drawing blood from a vein in children.
Mechanism of Action:
Local anesthetics are typically “lidocaine” or similar substances. These drugs temporarily block the sodium channels in nerve cells, preventing pain signals from reaching the brain.
To use a brief analogy, when you turn off the light switch at home, no electricity flows to the bulb and it does not light up. Local anesthetics similarly “switch off” the nerve pathway, extinguishing the “light” of pain.
Advantages:
The patient remains conscious, the procedure is short, and recovery is usually quick. Because very low doses are used, systemic side effects are quite rare. The numbness in the application area can also help reduce post-procedural pain.
Points to Note:
The doctor carefully adjusts the dose; if excessive amounts are given or the drug is accidentally injected into a blood vessel, systemic toxicity (e.g., heart rhythm issues, neurological symptoms) may appear.
Some local anesthetics contain “epinephrine” (adrenaline), which constricts blood vessels, keeping the drug in that area longer and facilitating bleeding control. However, caution is necessary in areas with circulation problems.
For small but potentially painful procedures, local anesthesia increases patient comfort and prevents the need for unnecessary deeper anesthesia methods. Its speed and convenience make it the first choice in many medical applications.
What Is Sedation and How Does It Differ from General Anesthesia?
Sedation is a state induced by drugs to relax the patient, reduce anxiety, and sometimes produce a light sleep-like condition. Here, the primary goal is not total loss of consciousness but rather a semi-conscious or less responsive state. General anesthesia, however, involves the patient losing consciousness entirely, with breathing and other reflexes being suppressed much more profoundly.
Different Levels of Sedation Depth:
Light (Minimal) Sedation: The patient is typically awake but calmer. For instance, this level of sedation may suffice for patients with dental procedure anxiety or before endoscopy. The patient can respond to questions but has a reduced level of anxiety.
Moderate Sedation: The patient appears drowsy but can respond to strong stimuli. The pain threshold is raised, and the discomfort felt during the procedure is minimal.
Deep Sedation: The patient barely responds to external stimuli, practically in a sleep-like state. Some respiratory support may be needed, but, unlike in general anesthesia, full muscle relaxation or intubation is not typically required.
Advantages:
During sedation, the patient generally continues breathing spontaneously, and maintaining airway security is easier. It is ideal for short procedures, painful diagnostic procedures (like colonoscopy, endoscopy), or minor surgeries. Since sedation reduces the patient’s anxiety, the medical team can work more comfortably, and the patient experiences lower stress.
Comparison with General Anesthesia:
Level of Consciousness: General anesthesia involves complete loss of consciousness, while sedation usually preserves consciousness or only lightly suppresses it.
Reflexes: In general anesthesia, protective reflexes (like coughing, swallowing) are largely suppressed. In sedation, they usually remain intact.
Side Effect Profile: Sedation generally has fewer side effects, and recovery may be quicker. However, due to issues like overdose or individual sensitivity, breathing difficulties or cardiovascular changes can still occur.
The main distinction between sedation and general anesthesia is how much consciousness is suppressed and the degree of respiratory support needed. Many patients find having a procedure under sedation less “frightening.” However, for certain major surgeries, general anesthesia is mandatory.
Op. Dr. Yunus Kaplan was born in Iskenderun in 1979. He graduated from the Gaziantep University Faculty of Medicine in 2001 and completed his specialization in Otolaryngology in 2009. He has worked at various public and private hospitals. Since 2020, he has been accepting patients in the field of rhinoplasty at his private clinic in Istanbul Nişantaşı.
