The term "anesthesia", derived from the ancient Greek for "absence of sensation", refers to a set of medical techniques whose primary objective is to suppress or alleviate pain and other sensations during a medical procedure, whether it be surgical, diagnostic, or obstetric. Anesthesia has revolutionized medicine, allowing for interventions that were previously unthinkable or excessively painful, ensuring both patient comfort and safety.
Its application and management are the responsibility of the anesthesiologist-intensivist (a specialist physician), who not only ensures the patient's insensibility during the procedure but also constantly monitors and manages their vital functions (heart, breathing, nervous system) before, during, and after the intervention.
The Main Types of Anesthesia
There are several forms of anesthesia; the choice of the most appropriate technique is determined by the nature and duration of the procedure, the location of the area to be operated on, and the patient's general health.
1. General Anesthesia (GA)
General anesthesia is a technique that induces a state of reversible loss of consciousness and all sensation in the patient. It is used for major or lengthy procedures, or those requiring complete immobility and total insensibility of the body.
The Components of GA: GA relies on a combination of several classes of drugs to achieve a complete anesthetic state:
- Hypnotics : These are the drugs that induce sleep (unconsciousness). They are most often administered intravenously (Propofol, Etomidate) or, in some cases (e.g., in children), by inhalation (halogenated agents, nitrous oxide).
- Analgesics : These are generally powerful morphine derivatives (synthetic opioids like Sufentanil or Remifentanil) whose role is to reduce, or even eliminate, the pain response to the surgical stimulus. Morphine-free alternatives (Opioid-Free Anesthesia - OFA) are also being developed.
- Muscle Relaxants (or Paralytics) : Administered when necessary, they cause complete muscle relaxation, which is essential for certain surgeries (e.g., abdominal surgery) and to facilitate the placement of a respiratory support device (intubation tube).
Management of Breathing : During general anesthesia, the patient no longer breathes spontaneously when deeply asleep or paralyzed. The anesthesiologist must therefore take over the respiratory function using a ventilator. This is generally done by inserting a device into the airway : an endotracheal tube (into the trachea) or a laryngeal mask.
2. Regional Anesthesia
Regional anesthesia makes it possible to numb a specific part of the body (a limb, a region) while the patient remains conscious (or lightly sedated if they wish). Its principle is based on the reversible blocking of nerve conduction by injecting a local anesthetic near the nerves.
The Main Types of Regional Anesthesia :
- Central Neuraxial Blocks :
- Spinal Anesthesia : The local anesthetic is injected directly into the cerebrospinal fluid. It produces a rapid and effective anesthesia, often used for surgeries on the lower half of the body (lower limbs, urology).
- Epidural Anesthesia : The drug is injected into the epidural space, around the nerves of the spinal cord. Well-known in obstetrics for labor analgesia, it is also used for certain surgeries or for managing post-operative pain.
- Peripheral Nerve Blocks : The anesthetic is injected near a targeted nerve or nerve plexus (a bundle of nerves) to numb only the specific limb or area (arm, leg, hand, foot). The anesthesiologist often uses ultrasound or neurostimulation to precisely locate the nerve structure.
3. Other Techniques
- Combined Anesthesia : This combines general anesthesia with regional anesthesia for the operated area. The regional block helps reduce the amount of medication needed for the GA and ensures better pain management after the operation.
- Sedation-Analgesia (or Hypno-Sedation) : This sometimes combines hypnosis with light intravenous sedation and local anesthesia. The patient is relaxed and insensitive to pain but remains "cooperative" or conscious (conscious sedation).
The Anesthetic Process: Comprehensive Care
Anesthesia is a process that extends well beyond the duration of the surgical procedure itself.
1. The Pre-Anesthetic Consultation
This mandatory appointment is the key step in preparation. The anesthesiologist assesses the patient's health status, medical history, current medications, and potential risks. It is the time to inform the patient about the possible techniques, their benefits, and their risks. The doctor chooses the safest and most suitable technique for the planned procedure and the patient's profile.
2. Monitoring During Anesthesia
The anesthesia team provides constant and rigorous monitoring of vital functions (heart rate, blood pressure, oxygen saturation, respiratory function, temperature, and sometimes brain activity) using sophisticated monitors. This monitoring is systematic and regulated by law.
3. Recovery and Post-Interventional Monitoring
At the end of the procedure, the patient is taken to the Post-Anesthesia Care Unit (PACU), also known as the "recovery room." The goal is to ensure that the patient is fully awake (in the case of GA), that their vital functions are stable, and that their pain is effectively controlled before they return to their hospital room or are discharged.
Risks and Side Effects
Thanks to advances in pharmacology and monitoring techniques, anesthesia has become an extremely safe procedure. Serious risks (cardiac arrest, respiratory complications, severe allergic reactions) are extremely rare.
The most common side effects are generally temporary:
- General Anesthesia : Nausea and vomiting upon waking (less common today), chills, sore throat (related to the breathing device), muscle aches, or temporary memory or concentration problems.
- Regional Anesthesia : A drop in blood pressure, headaches (rare after spinal or epidural anesthesia), bruising at the injection site, or transient pain or numbness in the area served by the blocked nerve.