Complications of local anesthesia are adverse reactions resulting from the administration of local anesthetic drugs. Depending on the type of complication, the patient may have symptoms such as suffocation, impaired hemodynamics and intracardiac conduction, changes in the central nervous system, skin rash. The diagnosis is established on the basis of anamnesis and clinical manifestations, in some cases, an ECG, CT, radiography, ultrasound is prescribed. Specific treatment includes administration of antihistamines and corticosteroid hormones, infusion therapy, and discontinuation of anesthetic use. In severe cases, resuscitation is required.
Dangerous reactions to the introduction of local anesthetics are quite common. The frequency of their occurrence is 1 case per 150-200 uses of drugs of this group. Signs of skin allergy (urticaria) are detected in 90% of patients. About 6% of patients respond to the injection of the drug with swelling of the face, neck, and respiratory tract. Anaphylactic shock is detected in 3% of cases. The share of general toxic reactions, accompanied by damage to the central nervous system and the conducting apparatus of the heart, accounts for no more than 1%. There is no dependence on gender and age, complications are equally often found in all categories of the population. Up to 70% of adverse reactions occur in residents of developed countries, in the countries of the “third world” allergy is diagnosed much less often.
The main cause of allergic reactions is hypersensitivity to the components of the solution. The drug, once in the body, is transformed into an inferior antigen – hapten. Next, the hapten forms a complex with a protein and is perceived by the body as a foreign agent. The provoking factor is the peculiarities of the metabolism of a particular patient. Biotransformation of the drug may differ slightly from normal, which leads to the formation of complexes that cause allergies. The intensity of symptoms depends on the degree of sensitization of the body. In addition to hypersensitivity reactions, complications of local anesthesia arise for the following reasons:
- Medical error. It includes the wrong choice of an analgesic or its dosage, refusal to use vasoconstrictive substances in the composition of the medicinal solution, violation of manipulation techniques. All this mainly leads to toxic effects of drugs on the heart and brain, infectious processes. If the procedure is carried out incorrectly, damage to nerve trunks, blood vessels, and other structures may occur.
- Inadequate reaction. Excessive motor activity of the patient in response to the actions of a specialist sometimes causes the injection needle to break off. This happens more often with thin needles with a diameter of 0.6 mm (23G). In addition, with sudden movements of the patient, excessive traumatization of soft tissues, vascular and nerve damage is possible (if infiltration is performed near the neurovascular bundles).
- Prolonged anesthesia. If it is necessary to provide prolonged spinal anesthesia, the solution is fed into the epidural space through a thin catheter. The anesthetic is deposited around the nerves, its concentration becomes toxic. A persistent neurological deficit develops – the ponytail syndrome. Simultaneous administration of a large dose of the drug provokes total spinal anesthesia with motor blockade and depression of the medulla oblongata.
The pathogenesis of the negative effects of local anesthesia varies by types of adverse events. With allergies, there is an excessive activation of immune mechanisms, which leads to the development of inadequate protective processes. These processes provoke regional proliferation of fluid from the vascular bed, hemodynamic disorders (anaphylactic shock), hyperemia of the skin in certain areas. Toxic reactions are characterized by a violation of the polarization and depolarization of cells, a change in the work of cellular sodium channels. The toxic effect on the central nervous system is to disrupt the conduction of nerve impulses by stopping their transmission in the ganglia of the nervous system. Infectious complications arise as a result of getting into the wound and multiplying pathogenic flora, which the body cannot cope with on its own.
Complications of local anesthesia can be systematized for reasons, but this method of division is more important in the prevention of pathological conditions, and not in cases where it is necessary to stop an already developed reaction. To eliminate the consequences of manipulation, it is necessary to have a clear understanding of the processes occurring in the patient’s body, therefore, the most used classification is by type of adverse events and their prevalence:
- Defeat of the central nervous system. It is diagnosed both with the absorption of a large amount of anesthetic from the place of its administration, and with an erroneous intravascular infusion. It is characterized by severe neurotoxic phenomena, can be spinal and cerebral. With the spinal variety of pathology, there is a total suppression of reflex arcs, the work of the medulla oblongata. Cerebral intoxication leads to a violation of consciousness, communication functions, coordination.
- Defeat of the conducting system. It is especially often observed when using high doses of mecaine, lidocaine. These drugs suppress the electrical activity of the heart, slow down AV conduction in toxic doses, and aggravate atrioventricular blockade in its presence. All of the above can cause bradycardia and cardiac arrhythmias up to cardiac arrest.
- Allergies. They occur in the form of urticaria, angioedema, anaphylactic shock. The latter is considered the most severe form of hypersensitivity to the drug. Sometimes an allergy to m / a develops in the form of nonspecific phenomena: dizziness, general deterioration of well-being, slight respiratory depression, variable skin rash.
- Traumatization. Occurs when the technique of the procedure is violated or the patient’s sudden movements. If the nerve trunk is damaged, a pronounced pain syndrome is determined, a violation of the function of the limb. When it enters a blood vessel, a hematoma forms. There may be contractures, areas of skin ischemia, paresthesia phenomena.
- Infectious complications. They can occur in the form of regional inflammation, abscess, phlegmon of soft tissues. The most severe type is a systematized septic process (sepsis), which refers to life-threatening conditions and requires emergency hospitalization. For other bacterial processes, outpatient treatment is usually indicated, which can be conservative or operative.
An allergic reaction in the form of urticaria is accompanied by the formation of many red spots, somewhat rising above the unchanged areas of the skin. Marked itching is noted. With angioedema, there is a unilateral or bilateral increase in the size of the ears, lips, and soft tissues of the face. The most dangerous is the ANO of the respiratory tract, which manifests itself in the form of suffocation, inspiratory shortness of breath, wheezing, barking cough, acrocyanosis of the lips, earlobes, nails. In the absence of timely help, severe systemic hypoxia develops, the patient dies from lack of oxygen. Symptoms of anaphylactic shock include pallor or marbling of the skin, a sharp decrease in blood pressure, tachycardia, dilated pupils, impaired consciousness, a feeling of suffocation.
When the central nervous system is affected, dizziness, convulsions, ringing in the ears, a metallic taste in the mouth are observed. Nystagmus, speech disorders, dizziness, tremor, numbness of the oral cavity, tongue may be detected. The reaction from the CCC includes bradycardia, arrhythmia, dilation of peripheral vessels, decreased blood pressure, collapse. Fibrillation and asystole are possible. A typical symptom of vascular injury is a rapid increase in hematoma in the affected area. Palpation reveals moderate soreness, swelling. Getting a needle into the nerve trunk provokes a sharp attack of pain radiating along the damaged structure. Subsequently, some patients have stiffness of the limb, back pain, local sensitivity disorder.
Infectious processes are characterized by local and general symptoms. Local symptoms are tissue edema, local hyperemia, and an increase in body temperature in the area of inflammation. With the accumulation of pus, fluctuation is determined, visually a whitish zone (accumulation of purulent masses) can be viewed in the focus. Systemic manifestations include general hyperthermia, deterioration of well-being, pain in muscles and bones, changes in the psycho-emotional background. In severe processes, depression of consciousness, delirium, convulsions are observed. An infectious and toxic shock develops, leading to the centralization of blood circulation, hemodynamic disorders, and the death of the patient.
Usually complications of local anesthesia develop shortly after the drug is administered, so their diagnosis is carried out by the attending physician, most often a surgeon or an anesthesiologist-resuscitator. Delayed consequences (infection) can be detected by a polyclinic surgeon or a general practitioner when a patient visits a polyclinic. In most cases, the type and nature of the complications of local anesthesia is determined taking into account the anamnesis and external signs. Sometimes laboratory and instrumental studies are required to confirm the diagnosis. Diagnostic techniques include:
- Anamnesis collection, examination. The doctor finds out which interventions were performed in the recent past, which anesthetic was used. If the diagnosis is made by a specialist who performed the manipulation, this item is excluded. During the examination, characteristic clinical signs of a particular pathological condition are revealed.
- Laboratory test. In infectious processes, leukocytosis and an increase in ESR are detected in the patient’s blood. With the toxic effect of an anesthetic, there may be a shift in the pH to the acidic side, since the hydrogen index of anesthetics ranges from 3.5 to 6 units. Severe cardiac disorders lead to an increase in the activity of CPK, CFK MV, the appearance of specific markers. With allergies, the content of immunoglobulins in the blood increases.
- Instrumental examination. It is not prescribed for allergies. Signs of central nervous system damage require the exclusion of organic diseases by computed tomography. On the ECG, AV blockade and bradycardia are determined. With purulent processes, sonography, radiography, CT may be required to clarify the boundaries of the inflammatory focus.
With urticaria, the patient is prescribed systemic antihistamines. As a rule, this is enough to eliminate the manifestations of the disease. Edema of the respiratory tract requires intravenous infusion of corticosteroids, oxygen therapy. In severe situations, emergency conicotomy or tracheostomy is resorted to to ensure the patency of the respiratory tract. In anaphylactic shock, infusion therapy using colloidal solutions, the introduction of cardiotonics to maintain heart function and blood pressure is indicated. Hormonal, antihistamines, adrenaline are used.
Anticonvulsants are recommended for violations of the central nervous system. If necessary, the patient is put under anesthesia using injectable drugs. They provide respiratory support up to a ventilator. To accelerate the excretion of the anesthetic, volumetric infusions of saline solutions are performed, followed by the introduction of loop diuretics. Reactions from the heart are stopped with the help of atropine, pressor amines. In case of fibrillation, chemical or electrical defibrillation is performed. In case of cardiac arrest, cardiopulmonary resuscitation is indicated.
In case of infectious complications, antibacterial agents are prescribed. Perform the rehabilitation of the pathological focus with its opening, removal of purulent masses, installation of drains. To eliminate the pain syndrome, non-narcotic analgesics are used. Antimicrobial and wound healing ointments are applied under the occlusive dressing. Hematomas formed when a vessel is damaged usually do not require intervention, with compression of neighboring anatomical structures, the accumulated blood is removed. In case of injuries of nerve trunks, drugs are used to improve neuromuscular conduction, physiotherapy.
Prognosis and prevention
The prognosis for most reactions of complications of local anesthesia is favorable, with timely assistance, negative phenomena can be completely eliminated. Death or disability is possible with the development of anaphylactic shock, Quincke’s edema, bradyarrhythmia outside the walls of a medical institution. Severe complications of infectious processes are extremely rare. Prevention consists in the correct selection of the type and dose of anesthetic, mastery of manipulation techniques, informing the patient about the goals and course of the procedure. It is necessary to strictly observe the rules of asepsis and antiseptics. The patient should inform the doctor in advance about the presence of an allergy to medications, behave as restrained as possible during the intervention, avoid sudden movements.