Pulsus paradoxus
Encyclopedia
In medicine
Medicine
Medicine is the science and art of healing. It encompasses a variety of health care practices evolved to maintain and restore health by the prevention and treatment of illness....

, a pulsus paradoxus (PP), also paradoxic pulse or paradoxical pulse, is defined as an exaggeration (more than 10 torr) of the normal variation during the inspiratory phase of respiration, in which the blood pressure declines as one inhales and increases as one exhales. It is a sign
Medical sign
A medical sign is an objective indication of some medical fact or characteristic that may be detected by a physician during a physical examination of a patient....

 that is indicative of several conditions including cardiac tamponade
Cardiac tamponade
Cardiac tamponade, also known as pericardial tamponade, is an emergency condition in which fluid accumulates in the pericardium ....

, pericarditis
Pericarditis
Pericarditis is an inflammation of the pericardium . A characteristic chest pain is often present.The causes of pericarditis are varied, including viral infections of the pericardium, idiopathic causes, uremic pericarditis, bacterial infections of the precardium Pericarditis is an inflammation of...

, chronic sleep apnea
Sleep apnea
Sleep apnea is a sleep disorder characterized by abnormal pauses in breathing or instances of abnormally low breathing, during sleep. Each pause in breathing, called an apnea, can last from a few seconds to minutes, and may occur 5 to 30 times or more an hour. Similarly, each abnormally low...

, croup
Croup
Croup is a respiratory condition that is usually triggered by an acute viral infection of the upper airway. The infection leads to swelling inside the throat, which interferes with normal breathing and produces the classical symptoms of a "barking" cough, stridor, and hoarseness...

, and obstructive lung disease
Obstructive lung disease
Obstructive lung disease is a category of respiratory disease characterized by airway obstruction. It is generally characterized by inflamed and easily collapsible airways, obstruction to airflow, and frequent office visits and hospitalizations. Types of obstructive lung disease include; Asthma,...

 (e.g. asthma
Asthma
Asthma is the common chronic inflammatory disease of the airways characterized by variable and recurring symptoms, reversible airflow obstruction, and bronchospasm. Symptoms include wheezing, coughing, chest tightness, and shortness of breath...

, COPD
Chronic obstructive pulmonary disease
Chronic obstructive pulmonary disease , also known as chronic obstructive lung disease , chronic obstructive airway disease , chronic airflow limitation and chronic obstructive respiratory disease , is the co-occurrence of chronic bronchitis and emphysema, a pair of commonly co-existing diseases...

).

The paradox in pulsus paradoxus is that, on clinical examination, one can detect beats on cardiac auscultation during inspiration that cannot be palpated at the radial
Radial artery
In human anatomy, the radial artery is the main blood vessel, with oxygenated blood, of the lateral aspect of the forearm.-Course:The radial artery arises from the bifurcation of the brachial artery in the cubital fossa. It runs distally on the anterior part of the forearm...

 pulse
Pulse
In medicine, one's pulse represents the tactile arterial palpation of the heartbeat by trained fingertips. The pulse may be palpated in any place that allows an artery to be compressed against a bone, such as at the neck , at the wrist , behind the knee , on the inside of the elbow , and near the...

. It results from an accentuated decrease of the blood pressure, which leads to the (radial) pulse not being palpable and may be accompanied by an increase in the jugular venous pressure
Jugular venous pressure
The jugular venous pressure is the indirectly observed pressure over the venous system...

 height (Kussmaul's sign
Kussmaul's sign
Kussmaul's sign is the observation of a rise in jugular venous pressure on inspiration. It can be seen in some forms of heart disease and is usually indicative of limited right ventricular filling.-Background:...

). As is usual with inspiration, the heart rate
Heart rate
Heart rate is the number of heartbeats per unit of time, typically expressed as beats per minute . Heart rate can vary as the body's need to absorb oxygen and excrete carbon dioxide changes, such as during exercise or sleep....

 is slightly increased, due to decreased left ventricular output.

Mechanism of reduced blood pressure during inspiration in normal conditions and in tamponade

Normally during inspiration, systolic blood pressure decreases ≤10 mmHg., and pulse rate goes up slightly. This is because the intrathoracic pressure becomes more negative relative to atmospheric pressure. This increases systemic venous return, so more blood flows into the right side of the heart. However, the decrease in intrathoracic pressure also expands the compliant pulmonary vasculature. This increase in pulmonary blood capacity pools the blood in the lungs, and decreases pulmonary venous return, so flow is reduced to the left side of the heart. Also the increased systemic venous return to the right side of the heart expands the right heart and directly compromises filling of the left side of the heart. Reduced left-heart filling leads to a reduced stroke volume which manifests as a decrease in systolic blood pressure. The decrease in systolic blood pressure leads to a faster heart rate due to the baroreceptor reflex, which stimulates sympathetic outflow to the heart.

Some people claim that during inspiration, the increased volume of the right ventricle causes the septum to bulge dramatically into the left ventricle, but this is unlikely as there is still a large pressure gradient between the right and left ventricle during inspiration. However, during cardiac tamponade this is NOT the case. Here there is an equalization of pressures among all of the chambers of the heart . This means that there is a zero-sum game and as the right ventricle gets more volume, it can push the septum into the left ventricle and therefore reduce the volume of the left ventricle. This additional loss of volume of the left ventricle that ONLY occurs when there is a equalization of the pressures (as in tamponade) allows for the further reduction in volume and therefore a reduced cardiac output leading to a further decline in BP. However, in situations where there the left ventricular pressure remains higher than the pericardial sac (most frequently from coexisting disease with an elevated left ventricular diastolic pressure), there is no pulsus paradoxus .

Although one or both of these mechanisms may occur, a third may additionally contribute. The large negative intrathoracic pressure increases the pressure across the wall of the left ventricle (increased transmural pressure, equivalent to [pressure within ventricle] - [pressure outside of ventricle]). This pressure gradient, resisting the contraction of the left ventricle, causes an increase in afterload
Afterload
Afterload is the tension or stress developed in the wall of the left ventricle during ejection. Following Laplace's law, the tension upon the muscle fibers in the heart wall is the product of the pressure within the ventricle, multiplied by the volume within the ventricle, divided by the wall...

. This results in a decrease in stroke volume
Stroke volume
In cardiovascular physiology, stroke volume is the volume of blood pumped from one ventricle of the heart with each beat. SV is calculated using measurements of ventricle volumes from an echocardiogram and subtracting the volume of the blood in the ventricle at the end of a beat from the volume...

, contributing to the decreased pulse pressure
Pulse pressure
Pulse Pressure is most easily defined as being the amount of pressure required to create the feeling of a pulse. Measured in millimeters of mercury , the pressure difference between the systolic and diastolic pressures give you the amount of pressure change to create the pulse, which is the pulse...

 and increased heart rate as described above.

Measurement of PP

PP is quantified using a blood pressure cuff and stethoscope (Korotkoff
Nikolai Korotkov
Nikolai Sergeyevich Korotkov was a Russian surgeon, a pioneer of 20th century vascular surgery, and the inventor of auscultatory technique for blood pressure measurement.-Associated eponyms:...

 sounds), by measuring the variation of the systolic pressure during expiration and inspiration. Inflate cuff until no sounds (as is normally done when taking a BP) slowly decrease cuff pressure until systolic sounds are first heard during expiration but not during inspiration, (note this reading), slowly continue decreasing the cuff pressure until sounds are heard throughout the respiratory cycle, (inspiration and expiration)(note this second reading). If the pressure difference between the two readings is >10mmHg, it can be classified as pulsus paradoxus.

Predictive value for tamponade

PP has been shown to be predictive of the severity of cardiac tamponade.

Causes

Pulsus paradoxus can be caused by several physiologic mechanisms. Anatomically, these can be grouped into:
  • cardiac causes,
  • pulmonary causes and
  • non-pulmonary and non-cardiac causes.


Considered physiologically, PP is caused by:
  • decreased right heart functional reserve, e.g. myocardial infarction and tamponade,
  • right ventricular inflow or outflow obstruction, e.g. superior vena cava obstruction and pulmonary embolism, and
  • decreased blood to the left heart due to lung hyperinflation (e.g. asthma, COPD) and anaphylactic shock.

List of causes

Cardiac:
  • cardiac tamponade
    Cardiac tamponade
    Cardiac tamponade, also known as pericardial tamponade, is an emergency condition in which fluid accumulates in the pericardium ....

  • constrictive pericarditis
    Constrictive pericarditis
    In many cases, constrictive pericarditis is a late sequela, in other words a condition that is the consequence of a previous disease, of an inflammatory condition of the pericardium...

    . One study found that pulsus paradoxus occurs in less than 20% of patients with constrictive pericarditis.
  • pericardial effusion
    Pericardial effusion
    Pericardial effusion is an abnormal accumulation of fluid in the pericardial cavity. Because of the limited amount of space in the pericardial cavity, fluid accumulation will lead to an increased intrapericardial pressure and this can negatively affect heart function...

  • pulmonary embolism
    Pulmonary embolism
    Pulmonary embolism is a blockage of the main artery of the lung or one of its branches by a substance that has travelled from elsewhere in the body through the bloodstream . Usually this is due to embolism of a thrombus from the deep veins in the legs, a process termed venous thromboembolism...

  • cardiogenic shock
    Cardiogenic shock
    Cardiogenic shock is based upon an inadequate circulation of blood due to primary failure of the ventricles of the heart to function effectively....



Pulmonary:
  • tension pneumothorax
  • asthma
    Asthma
    Asthma is the common chronic inflammatory disease of the airways characterized by variable and recurring symptoms, reversible airflow obstruction, and bronchospasm. Symptoms include wheezing, coughing, chest tightness, and shortness of breath...

  • chronic obstructive pulmonary disease
    Chronic obstructive pulmonary disease
    Chronic obstructive pulmonary disease , also known as chronic obstructive lung disease , chronic obstructive airway disease , chronic airflow limitation and chronic obstructive respiratory disease , is the co-occurrence of chronic bronchitis and emphysema, a pair of commonly co-existing diseases...



Non-pulmonary and non-cardiac:
  • anaphylactic shock
  • superior vena cava
    Superior vena cava
    The superior vena cava is truly superior, a large diameter, yet short, vein that carries deoxygenated blood from the upper half of the body to the heart's right atrium...

     obstruction

See also

  • Precordial exam
  • Pulsus alternans
    Pulsus alternans
    Pulsus alternans is a physical finding with arterial pulse waveform showing alternating strong and weak beats. It is almost always indicative of left ventricular systolic impairment, and carries a poor prognosis.-Pathophysiology:...

  • List of paradoxes

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
x
OK