Clinical Signs in Medicine: Pulsus Paradoxus

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Pulsus paradoxus, a physical sign of tremendous diagnostic ment of this “pulse” is by measurement of the “systolic blood and prognostic significance can be seen in a variety of cardiac pressure”. The mechanisms in various pathologies are dis- and extra-cardiac conditions. This article will discuss the cussed below. mechanism, pathophysiology, detection and management of patient with pulsus paradoxus. Causes of Pulsus Paradoxus Cardiac causes Historical Aspects 1. Cardiac tamponade The reduction in pulse volume during inspiration was first 2. Pericardial effusion described by Lomer in 1669 in constrictive pericarditis1. A simi- 3. Constrictive pericarditis lar finding was described by Floyer and later by William in 4. Restrictive cardiomyopathy4 1850 in bronchial asthma1. Adolf Kussmaul (Freiberg, Ger- 5. Pulmonary embolism many) coined the term “pulsus paradoxus” in 1873 in three 6. Acute myocardial infarction patients with constrictive pericarditis. The “paradox” was: (1) 7. Cardiogenic shock the discrepancy between the absence of the pulse and present Extracardiac pulmonary causes corresponding heart beat and (2) Amidst this irregularity, the 1. Bronchial asthma regularity with which the pulse disappeared during inspira- 2. Tension pneumothorax tion.1 Extracardiac non-pulmonary causes 1. Anaphylactic shock (during urokinase administration)5 Respiratory Influences on the Pulse Volume 2. Volvulus of the stomach6 Under normal conditions, arterial blood pressure fluctuates 3. Diaphragmatic hernia6 throughout the respiratory cycle, falling with inspiration and 4. Superior vena cava obstruction4 rising with expiration. The changes in the intrathoracic pres- 5. Extreme obesity sures during breathing are transmitted to the heart and great vessels. During inspiration, the right ventricle distends due to Mechanisms and Pathophysiology increased venous return, the interventricular septum bulges As a general guideline, pulsus paradoxus will be a result of the into the left ventricle reducing its size (reversed Bernheim ef- following mechanisms operating alone or in combination:4 fect), and increased pooling on blood in the expanded lungs 1. Limitation in increase in inspiratory blood flow to the right decreases return to the left ventricle, decreasing the stroke ventricle and pulmonary artery volume of the left ventricle. Additionally, negative intratho- 2. Greater than normal pooling of blood in the pulmonary racic pressure during inspiration is transmitted to the aorta. circulation The relatively higher negative pressure in the pulmonary cir- 3. Wide excursions in the intrathoracic pressure during in- culation compared to the left atrium in patients with pericar- spiration and expiration dial pathology causes back flow of blood from the left atrium 4. Interference with venous return to either atrium especially into the pulmonary veins during inspiration.2 during inspiration Therefore, during inspiration the fall in the left ventricular stroke volume is reflected as a fall in the systolic blood pres- In this review the pathophysiology underlying only the major sure. The converse is true for expiration. During quiet respira- causes will be discussed. tion, the changes in the intrathoracic pressures and blood pressure are minor. The accepted upper limit for fall in systolic Constrictive Pericarditis and Cardiac Tamponade blood pressure with inspiration is 10 mmHg. Pulsus paradoxus has great diagnostic significance in pericardial disease. The following mechanisms are proposed to op- Pulsus Paradoxus: What is the Paradox? erate: The “paradox” refers to the fact that heart sounds may be 1. Tense fluid accumulation within the pericardial sac im- heard over the precordium when the radial pulse is not felt.3 pairs left ventricular filling causing an exaggerated reduc- This is due to an exaggeration of the normal mechanisms tion in systolic blood pressure during inspiration. Katz and mentioned above. Moreover, the clinical method of assess- Gauchat found that with pericardial tamponade,

 2002 Journal of Postgraduate Medicine. Online full text at http://www.jpgmonline.com46 Khasnis A et al: Pulsus Paradox

intrapericardial pressure did not fall during inspiration.4 Pulsus paradoxus in acute myocardial infarction can result from As a result, the pulmonary venous pressure would fall right ventricular infarction, cardiogenic shock or cardiac tam- more than the left atrial pressure during inspiration tend- ponade. However, it has been described in uncomplicated ing to cause a fall in the left ventricular filling during in- myocardial infarction due to the differences in the compli- spiration due to incomplete transmission of the inspira- ance of the left atrium, left ventricle and pulmonary circula- tory fall of intrathoracic pressure to the left atrium. This tion that is further exaggerated by an increase in the left ven- has been documented in other studies as well. Dock7 pro- tricular stiffness due to myocardial ischaemia.16 posed that the inspiratory traction by the diaphragm and mediastinum upon the taut pericardium further increased Respiratory Diseases intrapericardial pressure thus interfering with cardiac fill- Pulsus paradoxus is one of the ominous signs in acute exacer- ing. Shabetai8 found that both vena caval and pulmo- bation of bronchial asthma. This is the most common extra- nary arterial blood flow velocity fail to increase normally cardiac cause of this physical sign. The main mechanism op- during inspiration in patients with constrictive pericardi- erational in respiratory disease is the unusually great fluctua- tis. tions in intrathoracic pressures that are transmitted to the aorta. 2. Fowler et al9 showed that there is a persistence of the nor- The following theories have been proposed: mal inspiratory increase of the filling of the right side of 1. During increased airway resistance, there is an exaggera- the heart during cardiac tamponade. If this was prevented, tion in the inspiratory-expiratory difference in stroke vol- paradoxical pulse did not develop, however severe the ume mediated primarily by the effects of intrathoracic pres- tamponade. Guntheroth et al10 proposed that the normal sure on ventricular preload. Shim et al17 found that pa- respiratory variations of a reduced right ventricular stroke tients of asthma with pulsus paradoxus had greater air- volume are responsible for the exaggerated respiratory flow obstruction than patients without. Also, it was often variations in blood pressure during cardiac tamponade. present in mild obstruction and absent in severe obstruc- 3. Pulsus paradoxus may be caused by pooling of blood in tion. In acute exacerbation of childhood asthma, pulsus the pulmonary circulation and competition of the ventri- paradoxus often correlates with both the severity and re- cles for filling within a relatively fixed pericardial space. sponse to bronchodilators.18 Few reports have highlighted abnormal movement of the 2. Hyperinflation of the chest due to air trapping is also plays interventricular septum during inspiration contributing to a role in pulsus paradoxus. Factors other than hyperinfla- decreased LV volume.11,12 Similar respiratory changes in tion also contribute to the fall in systolic pressure that oc- mitral and septal motions and the similar respiratory in- curs at full inflation of the lungs. This is also observed in teraction between the right and left ventricles have been patients with chronic stable obstructive airway disease.19 observed during the Mueller manoeuvre. These observations suggest decreased left ventricular filling and left ven- Pulsus Paradoxus in Hypovolaemic Shock tricular end-diastolic volume during inspiration in the pres- Hypovolaemia may precipitate pulsus paradoxus in critically ence of pulsus paradoxus. Large pericardial fluid collec- ill patients. Its occurrence may aid in the clinical recognition tions may affect left ventricular function even in the ab- of the common syndrome of occult hypovolaemia in patients sence of clinical manifestations.13 with shock and no obvious blood loss.20 4. One of the other principal causes for pulsus paradoxus is underfilling of the left ventricle during the preceding di- Measurement of Pulsus Paradoxus astole. This is the most likely cause of this combination of Cuff sphygmomanometry events.14 The patient should be instructed not to breathe too deeply (enough to make the chest movements easily visible). The Acute Massive Pulmonary Embolism sphygmomanometer cuff is inflated above systolic pressure. The pulsus paradoxus in this condition results from right ven- Korotkoff sounds are sought over the brachial artery while the tricular dysfunction secondary to acute right ventricular dila- cuff is deflated at rate of approximately 2 to 3 mm Hg per tion and excessive pooling of blood in the lungs in inspira- heartbeat. The peak systolic pressure during expiration should tion.15 first be identified and reconfirmed (when Korotkoff sounds are heard only during expiration). The cuff is then deflated Acute Myocardial Infarction slowly to establish the pressure at which Korotkoff sounds

47 J Postgrad Med 2002;48:46-49 Khasnis A et al: Pulsus Paradox become audible during both inspiration and expiration (when be felt in all the accessible arteries (2) There is no need for the Korotkoff sounds are heard during both inspiration and deep inspiration and (3) There must be no irregularity of car- expiration). When the differences between these two levels diac action. exceeds 10 mm Hg during quiet respiration, a paradoxical pulse is present. Absent Pulsus Paradoxus in Cardiac Tamponade4,15,23 Palpation All cases of cardiac tamponade are not accompanied by pul- Usually, palpation of the central pulses (carotid) is recom- sus paradoxus. The reasons for this are not clear in all cases, mended for the evaluation of the character of the pulse. How- but it is likely that other compensatory mechanisms are brought ever, pulsus paradoxus is better appreciated in the peripheral into play in order to maintain a normal systemic blood pres- pulses (radial).4 When the pulsus paradoxus is severe, it may sure. The following are such conditions: be possible to palpate a fall (reduction in the pulse volume) 1. Aortic regurgitation (AR): In the presence of AR, the left during the phase of inspiration and rise during the expiratory ventricle can fill from the aorta during inspiration. There- phase. fore, if aortic dissection produces both AR and tampon- Arterial waveform analysis ade, pulsus paradoxus may be absent. In the intensive care setting, where the arterial waveform is 2. Large atrial septal defect: The normal increase in systemic available, pulsus paradoxus can be diagnosed by visualising venous return on inspiration is balanced by a decrease in changes in the systolic blood pressure tracing during the in- the left to right shunt, resulting in minimal change in the spiratory and expiratory phases of respiration. right ventricular volume. Pulse oximetry waveform analysis21,22 3. Isolated right heart tamponade: This entity has been de- This technique has been found useful in the neonates with scribed in patients of chronic renal failure on hemodialysis cardiac tamponade. In patients with obstructive airway dis- 4. Elevated left ventricular diastolic pressures ease since pulse oximetry is available in ICUs and emergency 5. Severe rheumatoid spondylitis or disease of the bony tho- departments, it is a useful non-invasive means of continually rax: Wide changes in intrathoracic pressure prevented by assessing pulsus paradoxus and air trapping severity. the relative immobility of the chest wall. 6. Coexistent condition producing “reversed pulsus What is Reversed Pulsus Paradoxus? paradoxus” Reversed pulsus paradoxus, a rise in systolic blood pressure during inspiration, was first described by Massumi et al23 in Importance of Kussmaul’s Sign in Pulsus Paradoxus4 patients with idiopathic hypertrophic subaortic stenosis, Kussmaul’s sign is a paradoxical increase in the peripheral isorhythmic ventricular rhythm and patients of left ventricular venous distension and pressure during inspiration. The major failure on positive pressure ventilation. A rise in peak systolic mechanism is a change in the shape of the pericardium with a pressure on inspiration by more than 15 mm Hg is considered resulting increase in the intrapericardial pressure and obstruc- significant. In a mechanically ventilated patient, positive pres- tion to the venous return to the heart. Compare this with the sure ventilation displaces the ventricle wall inward during sys- marked exaggeration of the normal expiratory increase in ve- tole to assist in ventricular emptying causing a slight rise in the nous pressure that accompanies patients with pulmonary dis- systolic pressure during mechanical inspiration. A reverse pul- ease. Note that pulsus paradoxus may be present in both sus paradoxus in mechanically ventilated patients is a sensi- groups of patients. tive indicator of hypovolaemia. Approach to a Patient With Pulsus Paradoxus What is Pseudopulsus Paradoxus? Rule out common, important and life threatening causes first. Salel et al24 described a patient of complete heart block who 1. Careful history of the illness was misdiagnosed to have pulsus paradoxus. This was the 2. Haemodynamic status of the patient result of forfituous synchronism of inspiration with the cyclic 3. Meticulous examination of the jugular venous pulse – do intermittent properly timed atrial contribution to ventricular not forget Kussmaul’s sign and abdominojugular reflux filling characteristic of atrioventricular dissociation in this con- 4. Look for Beck’s triad (distended jugular veins, hypoten- dition. This is termed pseudopulsus paradoxus. This error can sion and muffled heart sounds) – suggestive of cardiac be avoided by strictly adhering to the guidelines for pulsus tamponade paradoxus laid down by Gauchat and Katz: (1) The pulse must 5. Detailed evaluation of the respiratory and cardiovascular

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systems 5. Ward GL, Heiselman DE, White LJ. Pulsus paradoxus in anaphylactic shock due to urokinase administration. Chest 1992;101:589. 6. X-ray chest and ECG may provide diagnosis or rule out 6. Hooper TL, Lawson RA. Volvulus of the stomach—an unusual cause some of the causes of pulsus paradoxus. Postgrad Med J 1986;62:377-9. MEDLINE 7. Emergent pericardiocentesis if large pericardial effusion 7. Dock W. Inspiratory traction on the pericardium: the cause of pulsus paradoxus in pericardial disease. Arch Intern Med 1961;108:837. 8. Aggressive management of asthma, exacerbation of ob- 8. Shabetai R, Fowler NO, Fenton JC, Masangkay M. Pulsus paradoxus. structive pulmonary disease, intercostal tube insertion/nee- J Clin Invest 1965;44:1882-98. 9. Fowler NO. Pericardial disease. In The Heart – Arteries and Veins 3rd dle insertion for tension pneumothorax Ed. Pg 1388 9. Thrombolysis for myocardial infarction or massive pul- 10. Shabetai R, Fowler NO, Guntheroth WG. The hemodynamics of car- monary embolism diac tamponade and constrictive pericarditis. Am J Cardiol 1970;26:480. 10. The other causes should be treated on their own merit 11. Cosio FG, Martinez JP, Serrano CM, de la Calada CS, Alcaine CC. Abnormal septal motion in cardiac tamponande with pulse paradoxus. Echocardiographic and hemodynamic observations. Chest 1977; 71: Limitations of Pulsus Paradoxus 787-8. MEDLINE Although pulsus paradoxus is a valuable physical sign, it 12. Anno Y, Matsuzaki M, Sada K, Sasada T, Fukagawa K, Sasaki T, et al. has its limitations. The use of the term is not uniform and as it Echocardiographic findings of pulsus paradoxus: cardiovascular changes due to respiration. J Cardiogr 1981;11:147-60. MEDLINE is an exaggeration of a normal phenomenon, a cut-off value 13. Wayne VS, Bishop RL, Spodick DH. Dynamic effects of pericardial is difficult to provide.25 In patients of cardiac tamponade, stud- effusion without tamponade. Respiratory responses in the absence of pulsus paradoxus. Br Heart J 1984;51:202-4. MEDLINE ies have shown that when right ventricular diastolic collapse 14. Fitchett DH, Sniderman AD. Inspiratory reduction in left heart filling on echocardiography and pulsus paradoxus were compared, as a mechanism of pulsus paradoxus in cardiac tamponade. Can J right ventricular diastolic collapse was more sensitive and more Cardiol 1990;6:348-54. MEDLINE 15. Constant J. Arterial pulses and pressures. In Bedside Cardiology 4th specific than pulsus paradoxus in detecting increases in Ed. Pg 63. intrapericardial pressure during euvolaemia and hypervolemia 16. Esteban A, Gomez-Acebo E, de la Cal MA. Pulsus paradoxus in acute myocardial infarction. Chest 1982;81:47-50. MEDLINE whereas the two tests were equally valuable in hypovolaemic 17. Shim C, Williams MH Jr. Pulsus paradoxus in asthma. Lancet states.26,27 As with other clinical signs, pulsus paradoxus must 1978;1:530-1. 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Detection of pulsus paradoxus associated with large pericardial effusions in pediatric patients by tially treatable causes are likely to be missed by the examining analysis of the pulse-oximetry waveform. Pediatrics 2002;109:673- physician. 7. MEDLINE 22. Chadwick V, Pearce S, Taylor B, Galland BC. Continuous non-invasive assessment of pulsus paradoxus. Lancet 1992 22;339:495-6. Khasnis A, Lokhandwala Y* 23. Massumi RA, Mason DT, Vera Z, Zelis R, Otero J, Amsterdam EA. “Reversed pulsus paradoxus”. N Engl J Med 1973; 1272–75. Departments of Medicine and Cardiology*, 24. Salel A, Amsterdam EA, Zelis R. Pseudopulsus paradoxus. Chest 1973;64:671-2. Seth G. S. Medical College and K. E. M. Hospital, Parel, 25. Henkind SJ, Benis AM, Teichholz LE. The paradox of pulsus Mumbai - 400 012, India. paradoxus. Am Heart J 1987;114(1 Pt 1):198-203. 26. Cogswell TL, Bernath GA, Wann LS, Hoffman RG, Brooks HL, Klopfenstein HS. 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