Ауырсынды уақытша тоқтату дәрілері және Гүнтер Грасс романы

Medications to reversibly block pain
the novel by Günter Grass

A local anesthetic (LA) is a medication that causes absence of all sensation (including pain) in a specific body part without loss of consciousness, providing local anesthesia, as opposed to a general anesthetic, which eliminates all sensation in the entire body and causes unconsciousness. When it is used on specific nerve pathways (local anesthetic nerve block), paralysis (loss of muscle function) also can be induced.

Chronic pain is a complex and often serious condition that requires diagnosis and treatment by an expert in pain medicine. LAs can be applied repeatedly or continuously for prolonged periods to relieve chronic pain, usually in combination with medication such as opioids, NSAIDs, and anticonvulsants. Though it can be easily performed, repeated local anesthetic blocks in chronic pain conditions are not recommended as there is no evidence of long term benefits.

Diagnostic tests such as bone marrow aspiration, lumbar puncture (spinal tap) and aspiration of cysts or other structures are made to be less painful upon administration of local anesthetic before insertion of larger needles. The side effects of inferior alveolar nerve block include feeling tense, clenching of the fists and moaning. The duration of soft tissue anesthesia is longer than pulpal anesthesia and is often associated with difficulty eating, drinking and speaking. There is risk of accidental damage to local blood vessels during injection of the local anesthetic solution. This is referred to as haematoma and could result in pain, trismus, swelling and/or discolouration of the region. The density of tissues surrounding the injured vessels is an important factor for haematoma. There is greatest chance of this occurring in a posterior superior alveolar nerve block or in a pterygomandibular block. Giving local anesthesia to patients with liver disease can have significant consequences. Thorough evaluation of the disease should be carried out to assess potential risk to the patient as in significant liver dysfunction, the half life of amide local anesthetic agents may be drastically increased thus increasing the risk of overdose. Local anesthetics and vasoconstrictors may be administered to pregnant patients however it is very important to be extra cautious when giving a pregnant patient any type of drug. Lidocaine can be safely used but bupivacaine and mepivacaine should be avoided. Consultation with the obstetrician is vital before administering any type of local anesthetic to a pregnant patient. >

When patients are emotionally affected in the form of nervousness or fear, it can lead to vasovagal collapse. This is the anticipation of pain during administration that activates the parasympathetic nervous system while inhibiting the orthosympathetic nervous system. What results is a dilation of arteries in muscles which can lead to a reduction in circulating blood volume inducing a temporary shortness of blood flow to the brain. Notable symptoms include restlessness, visibly looking pale, perspiration and possible loss of consciousness. In severe cases, clonic cramps resembling an epileptic insult may occur. A profound depression of brain functions may occur at even higher concentrations which may lead to coma, respiratory arrest, and death. Such tissue concentrations may be due to very high plasma levels after intravenous injection of a large dose. Another possibility is direct exposure of the central nervous system through the cerebrospinal fluid, i. e., overdose in spinal anesthesia or accidental injection into the subarachnoid space in epidural anesthesia.

Cardiac toxicity can result from improper injection of agent into a vessel. Even with proper administration, it is inevitable for some diffusion of agent into the body from the site of application due to unforeseeable anatomical idiosyncrasies of the patient. Toxicity from anesthetic combinations is additive. Therefore, amides can be used as alternatives in those patients. Nonallergic reactions may resemble allergy in their manifestations. In some cases, skin tests and provocative challenge may be necessary to establish a diagnosis of allergy. Also cases of allergy to paraben derivatives occur, which are often added as preservatives to local anesthetic solutions.

Methemoglobinemia is a process where iron in hemoglobin is altered, reducing its oxygen carrying capability, which produces cyanosis and symptoms of hypoxia. Exposure to aniline group chemicals such as benzocaine, lidocaine, and prilocaine can produce this effect, especially benzocaine. However, the evidence at this point is still limited. Though most case reports to date have recorded most common use of Intralipid, other emulsions, such as Liposyn and Medialipid, have also been shown effective. Ample supporting animal evidence One published case has been reported of successful treatment of refractory cardiac arrest in bupropion and lamotrigine overdose using lipid emulsion. The design of a 'homemade' lipid rescue kit has been described. Although lipid rescue mechanism of action is not completely understood, the added lipid in the blood stream may act as a sink, allowing for the removal of lipophilic toxins from affected tissues. This theory is compatible with two studies on lipid rescue for clomipramine toxicity in rabbits and with a clinical report on the use of lipid rescue in veterinary medicine to treat a puppy with moxidectin toxicosis.

All LAs are membrane stabilizing drugs; they reversibly decrease the rate of depolarization and repolarization of excitable membranes (like nociceptors). Though many other drugs also have membrane stabilizing properties, not all are used as LAs (propranolol, for example, though it has LA properties). LA drugs act mainly by inhibiting sodium influx through sodium specific ion channels in the neuronal cell membrane, in particular the so called voltage gated sodium channels. When the influx of sodium is interrupted, an action potential cannot arise and signal conduction is inhibited. The receptor site is thought to be located at the cytoplasmic (inner) portion of the sodium channel. Local anesthetic drugs bind more readily to sodium channels in an activated state, thus onset of neuronal blockade is faster in rapidly firing neurons. This is referred to as state dependent blockade. LAs are weak bases and are usually formulated as the hydrochloride salt to render them water soluble. At a pH equal to the protonated base's pKa, the protonated (ionized) and unprotonated (unionized) forms of the molecule exist in equimolar amounts, but only the unprotonated base diffuses readily across cell membranes. Once inside the cell, the local anesthetic will be in equilibrium, with the formation of the protonated (ionized) form, which does not readily pass back out of the cell. This is referred to as "ion trapping". In the protonated form, the molecule binds to the LA binding site on the inside of the ion channel near the cytoplasmic end. Most LAs work on the internal surface of the membrane the drug has to penetrate the cell membrane, which is achieved best in the nonionised form. This is exemplified by the permanently ionised LA RAC 421 II which cannot diffuse across the cell membrane but, if injected into the cytosol of a nerve fibre, can induce NaKATPase blockage and anesthetic effects. Acidosis such as caused by inflammation at a wound partly reduces the action of LAs. This is partly because most of the anesthetic is ionized and therefore unable to cross the cell membrane to reach its cytoplasmic facing site of action on the sodium channel.

The Vazirani–Akinosi technique is also known as the closed mouth mandibular nerve block. It is mostly used in patients who have limited opening of the mandible or in those that have trismus; spasm of the muscles of mastication. The nerves which are anesthetised in this technique are the inferior alveolar, incisive, mental, lingual and mylohyoid nerves. Dental needles are available in two lengths, short and long. As Vazirani–Akinosi is a local anesthetic technique which requires penetration of a significant thickness of soft tissues, a long needle is used. The needle is inserted into the soft tissue which covers the medial border of the mandibular ramus, in region of the inferior alveolar, lingual and mylohyoid nerves. The positioning of the bevel of the needle is very important as it must be positioned away from the bone of the mandibular ramus and instead towards the midline.

In Peru, the ancient Incas are believed to have used the leaves of the coca plant as a local anesthetic in addition to its stimulant properties. It was also used for slave payment and is thought to play a role in the subsequent destruction of Incas culture when Spaniards realized the effects of chewing the coca leaves and took advantage of it. Shortly after the first use of cocaine for topical anesthesia, blocks on peripheral nerves were described. Brachial plexus anesthesia by percutaneous injection through axillary and supraclavicular approaches was developed in the early 20th century. The search for the most effective and least traumatic approach for plexus anesthesia and peripheral nerve blocks continues to this day. In recent decades, continuous regional anesthesia using catheters and automatic pumps has evolved as a method of pain therapy. Intravenous regional anesthesia was first described by August Bier in 1908. This technique is still in use and is remarkably safe when drugs of low systemic toxicity such as prilocaine are used. Spinal anesthesia was first used in 1885, but not introduced into clinical practice until 1899, when August Bier subjected himself to a clinical experiment in which he observed the anesthetic effect, but also the typical side effect of postpunctural headache. Within a few years, spinal anesthesia became widely used for surgical anesthesia and was accepted as a safe and effective technique. Although atraumatic (noncutting tip) cannulae and modern drugs are used today, the technique has otherwise changed very little over many decades. Epidural anesthesia by a caudal approach had been known in the early 20th century, but a well defined technique using lumbar injection was not developed until 1921, when Fidel Pagés published his article "Anestesia Metamérica". This technique was popularized in the 1930s and 1940s by Achile Mario Dogliotti. With the advent of thin, flexible catheters, continuous infusion and repeated injections have become possible, making epidural anesthesia still a highly successful technique. Besides its many uses for surgery, epidural anesthesia is particularly popular in obstetrics for the treatment of labor pain.