In: Anesthesia24 Sep 2009
Failure of local anesthetics to achieve profound analgesia may be related to:
• inaccurate anatomic placement of local anesthetic solution
• placing too little solution
• allowing insufficient time for it to diffuse and take effect
• injecting into inflamed or infected tissues
• using an outdated or improperly stored anesthetic solution.
It is recommended that a local anesthetic not be injected in infected tissue because of the risk of spreading the infection and the increased probability of achieving less than effective anesthetic results owing to the low pH within the infected tissue maintaining the ionized, non-lipid-soluble state to the anesthetic. Source your medication needs online. zetia medication home delivered
COMPLICATIONS OF LOCAL ANESTHETICS
• Spread of infection: occasionally infection may be spread into the tissues by the needle passing through a contaminated tissue or by the needle being contaminated before use.
• Hematoma: damage of a blood vessel by the tip of a needle may lead to bleeding into the tissues, resulting in the formation of a hematoma. Significant bleeding may produce swelling, act as an irritant to the tissues, and cause pain and trismus. Theoretically, the localized collection of blood becomes an ideal culture medium for bacteria, although infection of a hematoma is unusual.
• Nerve damage: rarely, during an injection the needle may pierce a nerve bundle during placement, producing an immediate electric shock sensation to the patient. It is usually followed by a partial sensory deficit, but subsequently a complete return to normal sensation usually follows.
• Blockade of the facial nerve: if the injection is given in close proximity to the facial nerve, a motor blockade causing temporary paralysis of the muscles of facial expression may occur. The effect may last for 12 hours. In such circumstances, the desired branch of the trigeminal nerve will not be anesthetized, and a subsequent injection will be required at the correct anatomic location to achieve the desired effect. viagra plus
Systemic complications include:
• Regional or systemic infection: the spread of infection within the perioral tissues can be potentially spread through planes of the head and neck by passage of a needle through an infected area.
• Endocarditis risk: injections such as the intraligamen-tary injection can force bacteria into the systemic circulation and cause bacterial endocarditis.
• Cardiovascular disease: patients with ischemic heart disease (angina pectoris (drug Norvasc is used to treat high blood pressure (hypertension) or angina), previous myocardial infarction) or who have had previous cardiac surgery or circulatory dysfunction such as cardiac failure, show higher plasma levels of lidocaine when compared with healthy subjects given the same dose. Therefore it is recommended that the maximum safe dose be halved in such patients. Low plasma potassium levels and acidosis also potentiate adverse effects of local anesthetics on the myocardium.
• Liver disease: patients with reduced hepatic function may exhibit an abnormally decreased rate of metabolism of amide local anesthetics, resulting in potentially toxic blood levels. Dosage levels must therefore be reduced for these patients.
• Pseudocholinesterase deficiency: local anesthetics of the ester type (eg, procaine) should be avoided in patients who have this rare familial enzyme defect as metabolism of these drugs is impaired. Ester-type local anesthetics are no longer routinely used for dental procedures.
• Methemoglobinemia: this is a rare complication caused by a metabolite of prilocaine that oxidizes the ferrous component of heme in red blood cells to the ferric state. This reduces their oxygen-delivering capacity and results in tissue hypoxia.
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