Angioneurotic Edema

-A general term applied to the development of acute edema in the subcutaneous or submucous tissues.

-Anesthetic help may be sought during an attack, when edema of the lips, tongue, or larynx may cause respiratory problems.

Causes:

-Angioedema may be secondary to the release of histamine, or many other vasoactive substances such as bradykinins, prostaglandins, or leukotrienes.

-It is thought that pediatric and adult angioedemas differ. Children are less likely to require intubation or tracheostomy than adults. Recent work in adults has shown substantial increases in plasma bradykinin during attacks of hereditary, acquired, or captopril-induced angioedema.

-The development of edema may be:

1. Part of a general anaphylactoid or anaphylactic reaction to a drug, bite, sting, or the ingestion of a substance.

2. A manifestation of hereditary angioneurotic edema, a condition caused by a deficiency of C1 esterase inhibitor.

3. A result of an acquired form of C1 esterase inhibitor deficiency which usually occurs in association with a B-lymphocyte malignancy.

4. A known side effect of a drug. Recently, there have been several cases of angioedema reported, usually involving the tongue, floor of the mouth, epiglottis, and aryepiglottic folds, secondary to treatment with ACE inhibitors. Most occur in the first week of treatment but may be delayed for up to a year. Can be associated with elevated serum bradykinin levels.

Presentation:

1. There may be a history of a predisposing factor. This can be ingestion of food or a drug, an infection, bite or sting, a family history of angioedema, or a B-lymphocytic malignancy.

2. Edema of subcutaneous tissue may occur alone or be accompanied by hypotension.

3. Patients taking ACE inhibitors have developed problems in the perioperative period. Angioedema of the tongue occurred 15 min after tracheal tube removal.

4. A patient with acquired C1 esterase inhibitor deficiency undergoing cardiopulmonary bypass had massive activation of the common pathway, coagulopathy, pulmonary edema, and circulatory collapse.

Management:

1. Assessment of severity of airway obstruction.

2. If the angioedema is part of an anaphylactic or anaphylactoid reaction:

a) Give epinephrine (adrenaline) IV or IM, 0.1–0.5 mg depending on the severity.

b) If the condition is severe and involves the glottis, an airway should be established, either by tracheal intubation, cricothyroidotomy, or tracheostomy.

c) Second-line treatment includes IV fluids, chlorpheniramine IV 10–20 mg, and steroids.

3. Hereditary angioneurotic edema, or acquired C1 esterase inhibitor deficiency. These do not respond to epinephrine (adrenaline) or antihistamines, but to replacement of the deficient inhibitor by either:

a) An infusion of fresh frozen plasma.

b) Purified C1 esterase inhibitor concentrate.

Read more ☛ Acquired C1 Esterase Inhibitor Deficiency

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Acquired C1 Esterase Inhibitor Deficiency

-This may be a familial or, more rarely, an acquired disorder involving the complement system.

-The acquired form is mostly associated with a B-lymphocyte malignancy, and antibodies have been detected against abnormal immunoglobulins present on the malignant B-cells. The reaction between the two causes C1 activation, which in turn produces a secondary reduction in the concentrations of C1, C2, and C4 and reduced functional activity of the C1 esterase inhibitor.

-This form must be distinguished from the physical forms of angioedema that occur in response to food, drugs, or insect bites, or in association with connective tissue disorders.

-Recently, many patients have developed angioedema in response to treatment with ACE inhibitors, particularly enalapril and captopril. Substantial increases in plasma bradykinin have been demonstrated during attacks of hereditary, acquired, and captopril-induced angioneurotic edema.

Preoperative Abnormalities:

1. Intermittent attacks of angioneurotic edema that can involve any part of the body, and result from extravasation of intravascular fluid and protein into subcutaneous and mucosal structures.

2. As with hereditary angioneurotic edema, there is a low level of C1 esterase inhibitor, and sometimes life-threatening episodes of edema of the upper airway may develop in response to stress or local trauma, particularly dental treatment. However, attacks of edema may occur without any obvious reason, and recurrent abdominal pain may be a presenting feature.

3. As with the hereditary form, epinephrine (adrenaline), antihistamines, and steroids are ineffective for prophylaxis, and for treatment of these attacks.

4. The two conditions may be distinguished by the fact that in the acquired form the onset is late, no family history is elicited, no complement abnormalities are found in the patient’s blood relatives, and the underlying malignancy may already have been diagnosed.

5. Differentiation may now be made on measurement of the C1q subunit of C1; patients with acquired deficiency have a decreased level of C1q, compared with those with the hereditary form, in whom the C1 level is normal.

Anesthetic Problems:

1. Tracheal intubation and manipulation of the upper airway may precipitate local angioneurotic edema, for which treatment with epinephrine (adrenaline), steroids, and antihistamines is ineffective. Edema may also occur after dental extractions.

2. Although tranexamic acid has been recommended to prevent attacks in both forms, venous thrombosis has been reported after its prophylactic use during surgery in the acquired disease.

Management:

1. Progestogen derivatives: Increase the hepatic synthesis of a C1 esterase inhibitor. Its prophylactic value is acquired and hereditary disorders have been reported.

a) Danazol (200 mg TDS) should be given preoperatively but may take several days to become effective.

b) Stanozolol (0.5–8 mg/day) can also be used.

-The lower levels will be required for maintenance, whilst higher levels may be needed in the initial stages. A patient with autoimmune C1 EI, who was known to be carrying a male fetus, was given short-term therapy at 40 weeks of gestation.

2. Tranexamic acid: It should be avoided in the acquired form, especially in the presence of a thrombocytosis.

3. Fresh frozen plasma, and C1 esterase inhibitor concentrate: Used as preoperative prophylaxis and treatment.

Read more ☛ Angioneurotic Edema

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Ebstein’s Anomaly

-A rare congenital cardiac abnormality.

-The septal and posterior cusps of the tricuspid valve are displaced downwards and are elongated, such that a varying amount of the right ventricle effectively forms part of the atrium. Its wall is thin and it contracts poorly. The remaining functional part of the right ventricle is therefore small.

-The foramen ovale is patent, or defective, in 80% of cases.

-The degree of abnormality of right ventricular function, and the size of the ASD, are probably the main determinants of the severity of the condition, which varies considerably.

-The right ventricular systolic pressure is low, and the RVEDP is elevated. Tricuspid incompetence can occur.

-There may be a right to left shunt, with cyanosis, on effort, and pulmonary hypertension, and right heart failure may supervene.

-The natural history of the disease is very variable. Fifty percent of cases present in infancy with cyanosis, and 42% die in the first 6 weeks of life.

-In those who survive to adulthood, symptoms may be precipitated by the onset of arrhythmias, or by pregnancy. A few patients remain asymptomatic, even as adults, although once symptoms develop, the disability can increase rapidly.

-A cardiothoracic ratio of ≥ 0.65 is a better predictor of sudden death than the symptomatic state, and those who developed atrial fibrillation died within 5 years. It has therefore been suggested that tricuspid surgery should be undertaken before the cardiothoracic ratio reaches 0.65.

Preoperative Abnormalities:

1. There may be a right to left shunt, with dyspnea and cyanosis at rest, or on moderate exertion. Alternatively, the patient may be asymptomatic.

2. Episodes of tachyarrhythmias occur in 25% of patients. Some provoke syncopal attacks.

3. The ECG may show varying abnormalities, including large peaked P waves, a long P–R interval, Wolff–Parkinson–White syndrome, RBBB, and right heart strain. Paroxysmal supraventricular tachycardia occurs in 15%, usually because of the presence of WPW syndrome.

4. Chest X-ray may show cardiomegaly, with a prominent right heart border, and poorly perfused lung fields.

5. Paradoxical systemic embolism and bacterial endocarditis may occur.

6. Many other lesions of the tricuspid valve or right ventricle may mimic Ebstein’s anomaly, therefore the discriminating clinical and echocardiographic features for correct diagnosis have been enumerated.

Anesthetic Problems:

These will depend upon the anatomical abnormality, the degree of right to left shunt, and the presence or absence of right heart failure.

1. Induction time is prolonged, because of the pooling of drugs in the large atrial chamber.

2. Intracardiac catheter insertion may be hazardous because it can provoke serious cardiac arrhythmias.

3. Air entering peripheral venous lines or any open veins at subatmospheric pressure may cause paradoxical air emboli.

4. Tachycardia is poorly tolerated because of impaired filling of the functionally small right ventricle.

5. Hypotension may increase the right to left shunt if present.

6. Hypoxia causes pulmonary vasoconstriction, which also increases a right to left shunt.

7. There is a risk of bacterial endocarditis, especially if a CVP line is in place.

8. Deterioration may occur in pregnancy because of a decrease in right ventricular function, and an increase in blood volume and cardiac output, or with the onset of arrhythmias.

Management:

1. The severity of the lesion must be assessed. In the presence of maternal cyanosis or arrhythmias during pregnancy, there should be close monitoring of both mother and fetus. Deterioration may occur, despite previous successful pregnancies.

2. Treatment of heart failure and arrhythmias.

3. Antibiotic prophylaxis against bacterial endocarditis.

4. If a CVP is used for monitoring, its tip should be kept within the superior vena cava. The use of intracardiac catheters should probably be avoided.

5. Techniques should aim to minimize tachycardia and hypotension.

6. Oxygen therapy increases pulmonary vasodilatation. Long-term maternal therapy is required during pregnancy from 14 weeks, to treat fetal hypoxia that is demonstrated by umbilical venous blood gases.

7. Several anesthetic techniques have been described. A two-catheter epidural technique can be used for vaginal delivery to minimize hypotension. Bupivacaine doses must be fractionated and saline rather than air used to site the epidural, to avoid paradoxical air emboli. Cesarean section under general anesthesia, preceded by fentanyl, and a neurolept analgesic technique for hysterectomy, have been described.

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