Pulsus Paradoxus: Cardiovascular Function and Assessment

Cardiovascular Assessment:

Pulsus Paradoxus

Assessing cardiac function, blood pressure and hemodynamic status play an important role during our overall patient assessment and treatment. Although 12 lead ECG evaluation is an essential part of patient assessment, especially cardiac etiology, understanding basic cardiac function plays a major role during treatment and overall patient status.

During normal hemodynamic conditions, during inspiration, adequate cardiac, vascular function and adequate blood volume, certain changes in blood pressure occur. Keep in mind, when we measure blood pressure, we are assessing arterial pressures, not venous.

• Normally during  exhalation and early inspiration, Cardiac Output (CO) decreases slightly, since the Left Ventricle (LV) does not have the adequate amount of space to expand for full capacity preload

•This drop in blood pressure is normally < 10mmHg

•The heart rate also increases, as a compensatory mechanism, in an attempt to maintain normal Oxygen Delivery (DO2)

In a short summary, this occurs due to:

•  Decreased intrathoracic pressures increase venous return to the Right Ventricle (RV), while increased pressures during exhalation, reduce venous return

•This increase in Central Venous Pressure (1-6mmHg) which reflects the pressure of the RV, increases the RV volume and capacity, forcing the Interventricular Septum (the wall dividing the ventricles) towards the left

•This Septum shift towards the left slightly reduces the LV capacity. This is even more marked during a Pericardial Effusion (fluid in the pericardial sac), where the LV can’t expand properly due to the pressure from the Septum and the pericardial sac, decreasing it’s internal diameter, leading to decreased Stroke Volume (SV) since it can’t produce a strong contraction

•A decrease in pulmonary vein blood volume to the LV due to blood pooling from increased lung expansion also reduces the amount of blood brought to the LV

 A decrease >10mmHg during the systolic pressures during inspiration, is considered a significant decrease in Left Ventricular (LV) volume, known as Pulsus Paradoxus. The term paradox refers to an audible cardiac cycle without a palpable pulse during this event.

An easy way to assess for Pulsus Paradoxus is by manual BP assessment.

  1. Inflate the blood pressure cuff until no sounds are heard
  2. Begin deflating the cuff at approximately 2-3mmHg/sec, until the first Korotkoff sound (normal auscultated blood pressure sound) during exhalation
  3. Then listen for the next Korotkoff sound during inspiration
  4. If the drop between the first sound and the next is > 10mmHg, then there is positive Pulsus Paradoxus

What does this mean?

The presence of Pulsus Paradoxus means that there is reduced Venous return to the heart which leads to reduced arterial blood pressure, decreasing CO.

The most common causes of of Pulsus Paradoxus include:

. Increased Pulmonary pressures during COPD (Chronic Obstructive Pulmonary Diesease) exacerbation or Asthma

For further information about Pulmonary Pressures, click on the link below:
http://www.ems12lead.com/2014/01/16/pulmonary-pressures-and-ecg-patterns/

. Cardiac Tamponade
. Pericardial effusions (can lead to tamponade)
. Cardiomyopathies
. Cadiomyopahty
. Post large Myocardial Infarction
. Hypovolemia

2 Comments

  • Shane says:

    Sorry I’m confused. I though an increase in intrathoracic pressure decreases pre-load to the heart and not increase it as mentioned here? Could anybody clear this up?

    Thanks!

    • Ivan Rios says:

      Shane, you are correct. Positive intrathoracic pressures decrease venous return (preload), while negative pressures increase it. Notice, the comment is saying that these pressures increase venous return, not increased intrathoracic pressures, however, I will update this portion so there won’t be any further confusion. During inspiration, intrathoracic pressures, which are mainly negative pressures because you’re pulling air into the lungs from the atmosphere, will increase venous return in combination with increased abdominal or diaphragmatic pressures.

      Thank you for your time and input.

      Ivan Rios

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EMS 12-Lead

Cardiac Rhythm Analysis, 12-Lead ECG Interpretation, Resuscitation
Comments
David Baumrind
All that wiggles isn’t Wellens’
@Gary, by all means, nitpick all you like. I agree with your assessment, and the post has been modified. Thank you for the feedback!
2014-08-30 17:28:16
Gary Huntress
All that wiggles isn’t Wellens’
Not to nitpick but is this really a "slightly leftward axis"? I and AVF are both positive. I put it at about +20 degrees, not leftward.
2014-08-30 11:49:35
Handsome Robb
87 YOM COMPLAINING OF CHEST DISCOMFORT AND DYSPNEA
CHF. 12-lead shows a sinus Tachycardia in the 120s with PACs, besides the anterior leads there's diffuse ST depression, the STE in the anterior leads can be explained by the LBBB, axis is good as well. I wish they posted the EtCO2 waveform so we could see but I'm assuming it's non-obstructive. The elevated EtCO2…
2014-08-30 08:08:22
Christopher Watford
“Bad heartburn” – 82 y.o. female without chest pain.
Brooks, Firstly, thank you for the warm welcome to the club. Secondly, the Glasgow algorithm's only published sens/spec for AMI is 51.6%/97.6% respectively (Tuscon STEMI Database). I've not been able to find any other publications. The GE Marquette 12SL algorithm has been widely studied, but is much older, and ranges in sensitivity from 48% to…
2014-08-29 16:50:14
CB
57 Year Old Male–Chest Discomfort
Given what he was doing (paint fumes on ladder painting) I would first question if the pain is reproducable. Yes his ekg isn't normal but looks like old inferior MI. And he is hypertensive. 02 a must. Def. would give ASA. First would give morphine and see how his cp and bp are. If still…
2014-08-29 11:37:25

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