Pulsus paradoxus
Pulsus paradoxus, or paradoxical pulse, is an exaggerated decline in blood pressure during inspiration. Normally, systolic pressure falls less than 10 mm Hg during inspiration. In pulsus paradoxus, it falls more than 10 mm Hg. (See Identifying pulse waveforms, page 650.) When systolic pressure falls more than 20 mm Hg, the peripheral pulses may be barely palpable or may disappear during inspiration.
Pulsus paradoxus is thought to result from an exaggerated inspirational increase in negative intrathoracic pressure. Normally, systolic pressure drops during inspiration because of blood pooling in the pulmonary system. This, in turn, reduces left ventricular filling and stroke volume and transmits negative intrathoracic pressure to the aorta. Conditions associated with large intrapleural pressure swings, such as asthma, or those that reduce left-sided heart filling, such as pericardial tamponade, produce pulsus paradoxus.
To accurately detect and measure pulsus paradoxus, use a sphygmomanometer or an intra-arterial monitoring device. Inflate the blood pressure cuff 10 to 20 mm Hg beyond the peak systolic pressure. Then deflate the cuff at a rate of 2 mm Hg/second until you hear the first Korotkoff sound during expiration. Note the systolic pressure. As you continue to slowly deflate the cuff, observe the patient’s respiratory pattern. If a pulsus paradoxus is present, the Korotkoff sounds will disappear with inspiration and return with expiration. Continue to deflate the cuff until you hear Korotkoff sounds during both inspiration and expiration and, again, note the systolic pressure. Subtract this reading from the first one to determine the degree of pulsus paradoxus. A difference of more than 10 mm Hg is abnormal.
You can also detect pulsus paradoxus by palpating the radial pulse over several cycles of slow inspiration and expiration. Marked pulse diminution during inspiration indicates pulsus paradoxus. When you check for pulsus paradoxus, remember that irregular heart rhythms and tachycardia cause variations in pulse amplitude and must be ruled out before a true pulsus paradoxus can be identified.
Emergency Interventions
A pulsus paradoxus may signal cardiac tamponade—a life-threatening complication of pericardial effusion that occurs when sufficient blood or fluid accumulates to compress the heart. When you detect pulsus paradoxus, quickly check the patient’s other vital signs. Check for additional signs and symptoms of cardiac tamponade, such as dyspnea, tachypnea, diaphoresis, jugular vein distention, tachycardia, narrowed pulse pressure, and hypotension. Emergency pericardiocentesis to aspirate blood or fluid from the pericardial sac may be necessary. Then evaluate the effectiveness of pericardiocentesis by measuring the degree of pulsus paradoxus; it should decrease after aspiration.
History and physical examination
If the patient doesn’t have cardiac tamponade, find out if he has a history of chronic cardiac or pulmonary disease. Ask about the development of associated signs and symptoms, such as a cough or chest pain. Auscultate for abnormal breath sounds.
Medical causes
Cardiac tamponade
Pulsus paradoxus commonly occurs with this disorder, but it may be difficult to detect if intrapericardial pressure rises abruptly and profound hypotension occurs. With severe tamponade, assessment also reveals these classic findings: hypotension, diminished or muffled heart sounds, and jugular vein distention. Related findings include chest pain, pericardial friction rub, narrowed pulse pressure, anxiety, restlessness, clammy skin, and hepatomegaly. Characteristic respiratory signs and symptoms include dyspnea, tachypnea, and cyanosis; the patient typically sits up and leans forward to facilitate breathing.
If cardiac tamponade develops gradually, pulsus paradoxus may be accompanied by weakness, anorexia, and weight loss. The patient may also report chest pain, but he won’t have muffled heart sounds or severe hypotension.
Chronic obstructive pulmonary disease (COPD)
The wide fluctuations in intrathoracic pressure that characterize this disorder produce pulsus paradoxus and possibly tachycardia. Other findings vary but may include dyspnea, tachypnea, wheezing, productive or nonproductive cough, accessory muscle use, barrel chest, and clubbing. The patient may show labored, pursed-lip breathing after exertion or even at rest. He typically sits up and leans forward to facilitate breathing. Auscultation reveals decreased breath sounds, rhonchi, and crackles. Weight loss, cyanosis, and edema may occur.
Pericarditis (chronic constrictive)
Pulsus paradoxus can occur in up to 50% of patients with this disorder. Other findings include pericardial friction rub, chest pain, exertional dyspnea, orthopnea, hepatomegaly, and ascites. The patient also exhibits peripheral edema and Kussmaul’s sign—jugular vein distention that becomes more prominent on inspiration.
Pulmonary embolism (massive)
Decreased left ventricular filling and stroke volume in massive pulmonary embolism produce pulsus paradoxus, as well as syncope and severe apprehension, dyspnea, tachypnea, and pleuritic chest pain. The patient appears cyanotic, with jugular vein distention. He may succumb to circulatory collapse, with hypotension and a weak, rapid pulse. Pulmonary infarction may produce hemoptysis along with decreased breath sounds and a pleural friction rub over the affected area.
Right ventricular infarction
This infarction may produce pulsus paradoxus and elevated jugular venous or central venous pressure. Other findings are similar to those of myocardial infarction.
Special considerations
Prepare the patient for an echocardiogram to visualize cardiac motion and to help determine the causative disorder. Also, monitor his vital signs and frequently check the degree of paradox. An increase in the degree of paradox may indicate recurring or worsening cardiac tamponade or impending respiratory arrest in severe COPD. Vigorous respiratory treatment, such as chest physiotherapy, may avert the need for endotracheal intubation.
Pediatric pointers
Pulsus paradoxus commonly occurs in children with chronic pulmonary disease, especially during an acute asthma attack. Children with pericarditis may also develop pulsus paradoxus due to cardiac tamponade, although this disorder more commonly affects adults. A pulsus paradoxus above 20 mm Hg is a reliable indicator of cardiac tamponade in children; a change of 10 to 20 mm Hg is equivocal.
Book Source Details
- Book Title: Professional Guide to Signs & Symptoms (Fifth Edition)
- Author(s): Springhouse
- Year of Publication: 2006
- Copyright Details: Professional Guide to Signs & Symptoms (Fifth Edition), Copyright © 2006 Lippincott Williams & Wilkins.
Other Book Chapters Related to Orthostatic hypotension
Read excerpts from these other book chapters related to Orthostatic hypotension:
Copyright Details: Professional Guide to Signs & Symptoms (Fifth Edition), Copyright © 2008 Williams & Wilkins.
More About Causes of Orthostatic hypotension
» Next page: Orthostatic hypotension [Postural hypotension] (Professional Guide to Signs & Symptoms (Fifth Edition))
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