Disautonomias Flashcards
Como abordar a historia de um paciente com hipotensão postural?
The first step in the evaluation of symptomatic OH is the exclusion of treatable causes. The history should include a review of medications that may affect the autonomic system. The main classes of (1) drugs that may cause OH are diuretics, antihypertensives, antidepressants, phenothiazines, ethanol, narcotics, in- sulin, dopamine agonists, barbiturates, and calcium channel-blocking agents. However, the precipitation of OH by medications may also be the first sign of an underlying autonomic disorder.
The history may reveal an underlying (2) cause for symptoms (e.g., diabetes, Parkinson’s disease) or specific underlying mechanisms (e.g., cardiac pump failure, reduced intravascular volume).
The (3) relationship of symptoms to meals (splanchnic pooling), standing on awakening in the morning (intravascular volume depletion), ambient warming (vasodilatation), or exercise (muscle arteriolar vasodilatation) should be sought.
(4) Standing time to first symptom and presyncope should be followed for management.
(5) Disorders of autonomic function should be considered in patients with symptoms of altered sweating (hyperhidrosis or hypohidrosis), gastroparesis (bloating, nausea, vomiting of old food), constipation, impotence, or bladder dysfunction (urinary frequency, hesitancy, or incontinence).
O que avaliar no exame físico da hipotensão postural?
(1) Physical examination includes measurement of supine and standing pulse and BP. OH is defined as a sustained drop in systolic (≥20 mmHg) or diastolic (≥10 mmHg) BP within 3 min of standing. In nonneurogenic causes of OH (such as hypovolemia), the BP drop is accompanied by a compensatory increase in heart rate of >15 beats/min. A clue that the patient has neurogenic OH is the aggravation or precipitation of OH by autonomic stressors (such as a meal, hot tub/hot bath, and exercise.
(2) Neurologic examination should include mental status (neurodegenerative disorders), cranial nerves (impaired downgaze with progressive supranuclear palsy; abnormal pupils with Horner’s or Adie’s syndrome), motor tone (Parkinson’s disease and parkinsonian syndromes), and reflexes and sensation (polyneuropathies). In patients without a clear diagnosis initially, follow-up evaluations may reveal the underlying cause
Como fazer o manejo nao farmacológico da hipotensão postural?
INITIAL TREATMENT OF ORTHOSTATIC HYPOTENSION (OH)
(1) Patient education: mechanisms and stressors of OH
(2) High-salt diet (10–20 g/d) (3) High-fluid intake (2 L/D) (4) Elevate head of bed 10 cm (4 in.)
(5) Maintain postural stimuli (6) Learn physical countermaneuvers
(7) Compression garments
(8) Correct anemia
Quais as medidas farmacológicas para hipotensão postural?
(1) Midodrine, a directly acting α1-agonist that does not cross the blood-brain barrier, is effective. It has a duration of action of 2–4 h. The usual dose is 5–10 mg orally tid, but some patients respond best to a decremental dose (e.g., 15 mg on awakening, 10 mg at noon, and 5 mg in the afternoon). Midodrine should not be taken after 6 P.M. Side effects include pruritus, uncomfortable piloerection, and supine hypertension especially at higher doses.
(2) Pyridostigmine appears to improve OH without aggravating supine hypertension by enhancing ganglionic transmission (maximal when orthostatic, minimal supine).
(3) Fludrocortisone will reduce OH, but it aggravates supine hypertension. At doses between 0.1 mg/d and 0.3 mg bid orally, it enhances renal sodium conservation and increases the sensitivity of arterioles to NE. Susceptible patients may develop fluid overload, congestive heart failure, supine hypertension, or hypokalemia. Potassium supplements are often necessary with chronic administration of fludrocortisone. Sustained elevations of supine BP >180/110 mmHg should be avoided.
