An absent or weak pulse may be generalized or may affect only one extremity. When generalized, this sign is an important indicator of such life-threatening conditions as shock and arrhythmia. Localized loss or weakness of a pulse that’s normally present and strong may indicate acute arterial occlusion, which could require emergency surgery. However, the pressure of palpation may temporarily diminish or obliterate superficial pulses, such as the posterior tibial or the dorsal pedal. Thus, bilateral weakness or absence of these pulses doesn’t necessarily indicate underlying pathology. (See Evaluating peripheral pulses.)
After you detect an absent or weak pulse, review the patient’s history of heart disease. Ask him what medications he’s taking and whether he has any other illnesses. Also, question him about associated signs and symptoms, such as chest pain or dyspnea.
If you detect an absent or weak pulse, palpate the remaining arterial pulses to distinguish between localized or generalized loss or weakness. (See Managing an absent or weak pulse, pages 532 and 533.) Then check other vital signs and evaluate cardiopulmonary status.
When a dissecting aneurysm affects circulation to the innominate, left common carotid, subclavian, or femoral artery, it causes weak or absent arterial pulses distal to the affected area. Absent or diminished pulses occur in 50% of patients with proximal dissection and usually involve the brachiocephalic vessels. Pulse deficits are much less common in patients with distal dissection and tend to involve the left subclavian and femoral arteries. Tearing pain usually develops suddenly in the chest and neck and may radiate to the upper and lower back and abdomen. Other findings include syncope, loss of consciousness, weakness or transient paralysis of the legs or arms, the diastolic murmur of aortic insufficiency, systemic hypotension, and mottled skin below the waist.
With aortic stenosis, the carotid pulse is sustained but weak. Dyspnea (especially paroxysmal dyspnea or dyspnea on exertion), chest pain, and syncope dominate the clinical picture. The patient commonly has an atrial gallop. Other findings include a harsh systolic ejection murmur, crackles, palpitations, fatigue, and narrowed pulse pressure.
With acute occlusion, arterial pulses distal to the obstruction are unilaterally weak and then absent. The affected limb is cool, pale, and cyanotic, with increased capillary refill time, and the patient complains of moderate to severe pain and paresthesia. A line of color and temperature demarcation develops at the level of obstruction. Varying degrees of limb paralysis may also occur, along with intense intermittent claudication. With chronic occlusion, occurring with such disorders as arteriosclerosis and Buerger’s disease, pulses in the affected limb weaken gradually.
Cardiac arrhythmias may produce generalized weak pulses accompanied by cool, clammy skin. Other findings reflect the arrhythmia’s severity and may include hypotension, chest pain, dyspnea, dizziness, and decreased level of consciousness (LOC).
Life-threatening cardiac tamponade causes a weak, rapid pulse accompanied by these classic findings: paradoxical pulse, jugular vein distention, hypotension, and muffled heart sounds. Narrowed pulse pressure, pericardial friction rub, and hepatomegaly may also occur. The patient may appear anxious, restless, and cyanotic and may have chest pain, clammy skin, dyspnea, and tachypnea.
Findings of this disorder include bounding pulses in the arms and neck, with decreased pulsations and systolic pulse pressure in the lower extremities. Auscultation may reveal a systolic ejection click at the base and apex of the heart and, occasionally, over the carotid arteries that’s often accompanied by a systolic ejection murmur at the base.
Peripheral vascular disease causes a weakening and loss of peripheral pulses. The patient complains of aching pain distal to the occlusion that worsens with exercise and abates with rest. The skin feels cool and shows decreased hair growth. Impotence may occur in male patients with occlusion in the descending aorta or femoral areas.
A pulmonary embolism causes a generalized weak, rapid pulse. It may also cause abrupt onset of chest pain, tachycardia, dyspnea, apprehension, syncope, diaphoresis, and cyanosis. Acute respiratory findings include tachypnea, dyspnea, decreased breath sounds, crackles, a pleural friction rub, and a cough — possibly with blood-tinged sputum.
With anaphylactic shock, pulses become rapid and weak and then uniformly absent within seconds or minutes after exposure to an allergen. This is preceded by hypotension, anxiety, restlessness, feelings of doom, intense itching, a pounding headache and, possibly, urticaria.
With cardiogenic shock, peripheral pulses are absent and central pulses are weak, depending on the degree of vascular collapse. Pulse pressure is narrow. Other signs include cold, pale, clammy skin; hypotension; tachycardia; rapid, shallow respirations; oliguria; restlessness; confusion; and obtundation.
With hypovolemic shock, all peripheral pulses become weak and then uniformly absent, depending on the severity of hypovolemia. As shock progresses, remaining pulses become thready and more rapid. Early signs of hypovolemic shock include restlessness, thirst, tachypnea, and cool, pale skin. Late signs include hypotension with narrowing pulse pressure, clammy skin, a drop in urine output to less than 25 ml/hour, confusion, decreased LOC and, possibly, hypothermia.
With septic shock, all pulses in the extremities first become weak. Depending on the degree of vascular collapse, pulses may then become uniformly absent. Shock is heralded by chills, sudden fever and, possibly, nausea, vomiting, and diarrhea. Typically, the patient experiences tachycardia, tachypnea, and flushed, warm, and dry skin. As shock progresses, he develops thirst, hypotension, anxiety, restlessness, and confusion. Then pulse pressure narrows, and the skin becomes cold, clammy, and cyanotic. The patient experiences severe hypotension, oliguria or anuria, respiratory failure, and coma.
In thoracic outlet syndrome, the patient may develop gradual or abrupt weakness or loss of the pulses in the arms, depending on how quickly vessels in the neck compress. These pulse changes commonly occur after the patient works with his hands above his shoulders, lifts a weight, or abducts his arm. Paresthesia and pain occur along the ulnar distribution of the arm and disappear as soon as the patient returns his arm to a neutral position. The patient may also have asymmetrical blood pressure and cool, pale skin.
Localized absent pulse may occur distal to arteriovenous shuntsfor dialysis.
Continue to monitor the patient’s vital signs to detect untoward changes in his condition. Monitor hemodynamic status by measuring daily weight and hourly or daily intake and output and by assessing central venous pressure.
Radial, dorsal pedal, and posterior tibial pulses aren’t easily palpable in infants and small children, so be careful not to mistake these normally hard-to-find pulses for weak or absent pulses. Instead, palpate the brachial, popliteal, or femoral pulses to evaluate arterial circulation to the extremities. In children and young adults, weak or absent femoral and more distal pulses may indicate coarctation of the aorta.
Teach the patient how to check his pulse. Advise him to call his health care provider if he has difficulty palpating or is unable to palpate a pulse. Explain the importance of following a low-sodium diet and maintaining fluid restrictions, if necessary. Discuss signs and symptoms of fluid overload to report to the health care provider. Teach the patient to avoid activities that reduce circulation, such as prolonged sitting and crossing the legs.
Read excerpts from these other book chapters related to Cardiac arrest:
Copyright Details: Signs & Symptoms: A 2-in-1 Reference for Nurses, Copyright © 2008 Williams & Wilkins.
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More About This Book:
Title: Signs & Symptoms: A 2-in-1 Reference for Nurses Authors: Springhouse Publisher: Lippincott Williams & Wilkins Copyright: 2007 ISBN: 1-58255-318-1 
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