To not fly blind in patients with advanced heart failure or cardiogenic shock, certain equations exist to help us manage our patients. This allows us to identify who is not doing well and act on their deterioration before it really hits the fan. We use cardiac power output (CPO), which I have dissected in THIS POST, to measure how the left heart is doing. Clinicians and researchers want to validate the aortic pulsatility index for those with cardiogenic shock secondary to decompensated heart failure. I introduce you to the pulmonary artery pulsatility index to measure how the right heart is doing.

After all, right ventricular (RV) dysfunction is a common complication of decompensated heart failure and acute myocardial infection, leading to cardiogenic shock and possibly death. I want to clarify right off the bat that, per Lim et al., “the PAPi is related to, but is not a direct measure of RV function.” The index is here to help us, not to be an absolute. I recommend you check out Lim’s article, which is far more thorough than this post.

Cite this post as Eddy J. Gutierrez, “Pulmonary Artery Pulsatility Index (PAPi),” eddyjoemd blog, July 6, 2022. Available at: http://eddyjoemd.com/papi/

How do we obtain a Pulmonary Artery Pulsatility Index (PAPi)?

Floating a Swan Ganz catheter would be best to obtain your patient’s pulmonary artery pulsatility index. This catheter is also called a pulmonary artery catheter. Yes, this is invasive. Then again, these patients are incredibly sick. We contemplate performing far more invasive procedures to save their lives, such as right-sided mechanical circulatory support.

How To Calculate the Pulmonary Artery Pulsatility Index (PAPi)?

To calculate PAPi, you need to plug the pulmonary artery’s pulse pressure into the equation. You subtract the systolic pulmonary artery pressure (sPAP) from the diastolic pulmonary artery pressure (dPAP). That pulse pressure is divided by the central venous pressure (CVP).

PAPi=(systolic pulmonary artery pressure-diastolic pulmonary artery pressure)/CVP

Instead of obtaining a PAPi, why don’t we just do an echo?

It is understandable if you want to limit the procedures performed on patients. Some may not have the comfort level to float a swan. An echocardiogram is a reasonable alternative to obtain. Obtaining views of the right heart via echocardiography is more complex. It is challenging to obtain windows in many patients for several reasons. I care for many post-op cardiac surgery patients who recently had a sternotomy. It is almost impossible to obtain a window sufficient to make a clinical determination. Sure, one could drop a TEE probe, but this skill set is less ubiquitous than we all wish it were. Heck, it has been several years since I have done this myself.

TAPSE

When performing an echo, we look at the tricuspid annular plane systolic excursion (TAPSE). Per Škulec et al., TAPSE is “evaluated from a four-chamber apical view, is an echocardiographic parameter for detecting right ventricular systolic dysfunction (RVD).” TAPSE “is measured from the apical four-chamber view using M-mode imaging.” A TAPSE < 16 mm is considered abnormal. Digging deeper into TAPSE is beyond the scope of this post.

Pulmonary Artery Pulsatility Index (PAPi) Score Interpretation

PAPi was first validated in 2012 in patients with acute myocardial infarction who had severe right ventricular dysfunction. For the sake of this post, we will ignore the cutoffs used for patients with implantable LVADs. If you’re looking for PAPi in LVAD patients, CLICK HERE for an article that could help you.

PAPi < 0.9
– indicates possible RV failure and that the clinician should consider RV support. Like everything in medicine, this is NOT an absolute.

PAPi > 0.9
– indicates that the RV is likely normal. This number is what is considered to be the normal range. Some literature uses PAPi > 1.0.

Limitations of the Pulmonary Artery Pulsatility Index (PAPi)

Kapur et al. state that PAPi has not been studied in patients with pulmonary hypertension. Pulmonary hypertension may reduce the accuracy of the pulmonary artery pulsatility index because the right heart has been remodeled. To my knowledge, I have not encountered any data on using PAPi in the post-cardiac surgery population or chronic heart failure.

What about s/p cardiac surgery and chronic decompensated right heart failure?

We do not have data on whether the pulmonary artery pulsatility index works for patients after cardiac surgery and decompensated heart failure. It likely works, but the magic number one may need to be corrected to determine if the RV is failing. LVAD patients, for example, had a happy right heart when the PAPi was two or higher. Some of us still use the number of one in practice in populations outside of the ones represented in clinical trials. Still, we have to be academically honest with ourselves, saying that this is guesswork rather than proven in the data.

How to Use PAPi in Practice

In my practice, most patients who come to the cardiac ICU in cardiogenic shock come after an acute myocardial infarction or decompensated heart failure. Before they are admitted to the ICU, they pass through the hands of our ER colleagues. Usually, a baseline echocardiogram is ordered. I typically place a probe on the patient’s chest to take a quick look if the echo techs are busy. I also usually have discussions with my cardiology colleagues as well. Depending on their hemodynamics and physical exam, I choose my monitoring device.

If their cardiogenic shock looks to be an isolated left heart issue, I will try using the pulse-contour analysis technology available at my shop. Sometimes, the one that goes on the finger provides sufficiently reliable numbers. Let’s be honest; cardiogenic shock patients have cold fingers, which affects the reliability of this device. An arterial line will be placed for more reliable numbers. A swan is in the patient’s cards if there are right heart issues. Consent needs to be obtained as floating a swan is not without risks. Once the swan is floated, I calculate a PAPi and a CPO. Suppose the PAPi is suboptimal and no immediately reversible issue could be resolved with a stent. In that case, it is time to consider mechanical circulatory support such as the ProtekDuo.

Keywords: pulmonary artery pulsatility index, PAPi, right ventricular function, heart failure, cardiogenic shock

Citations

Lim HS, Gustafsson F. Pulmonary artery pulsatility index: physiological basis and clinical application. Eur J Heart Fail. 2020 Jan;22(1):32-38. doi: 10.1002/ejhf.1679. Epub 2019 Nov 28. PMID: 31782244.
Link to Article
Link to FULL FREE PDF

Škulec R, Parizek T, Stadlerova B, Bilska M, Cerny V. Subcostal TAPSE measured by anatomical M-mode: prospective reliability clinical study in critically ill patients. Minerva Anestesiol. 2021 Nov;87(11):1200-1208. doi: 10.23736/S0375-9393.21.15464-1. Epub 2021 May 13. PMID: 33982987.
Link to Article
Link to FULL FREE PDF

Modin D, Møgelvang R, Andersen DM, Biering-Sørensen T. Right Ventricular Function Evaluated by Tricuspid Annular Plane Systolic Excursion Predicts Cardiovascular Death in the General Population. J Am Heart Assoc. 2019 May 21;8(10):e012197. doi: 10.1161/JAHA.119.012197. PMID: 31088196; PMCID: PMC6585329.
Link to Article
Link to FULL FREE PDF

Korabathina R, Heffernan KS, Paruchuri V, Patel AR, Mudd JO, Prutkin JM, Orr NM, Weintraub A, Kimmelstiel CD, Kapur NK. The pulmonary artery pulsatility index identifies severe right ventricular dysfunction in acute inferior myocardial infarction. Catheter Cardiovasc Interv. 2012 Oct 1;80(4):593-600. doi: 10.1002/ccd.23309. Epub 2012 Jan 10. PMID: 21954053.
Link to (NOT FREE) Article

Morine KJ, Kiernan MS, Pham DT, Paruchuri V, Denofrio D, Kapur NK. Pulmonary Artery Pulsatility Index Is Associated With Right Ventricular Failure After Left Ventricular Assist Device Surgery. J Card Fail. 2016 Feb;22(2):110-6. doi: 10.1016/j.cardfail.2015.10.019. Epub 2015 Nov 10. PMID: 26564619.
Link to (NOT FREE) Article

Kang G, Ha R, Banerjee D. Pulmonary artery pulsatility index predicts right ventricular failure after left ventricular assist device implantation. J Heart Lung Transplant. 2016 Jan;35(1):67-73. doi: 10.1016/j.healun.2015.06.009. Epub 2015 Jun 17. Erratum in: J Heart Lung Transplant. 2017 Nov;36(11):1272. PMID: 26212656.
Link to Article
Link to FULL FREE PDF

Kapur NK, Esposito ML, Bader Y, Morine KJ, Kiernan MS, Pham DT, Burkhoff D. Mechanical Circulatory Support Devices for Acute Right Ventricular Failure. Circulation. 2017 Jul 18;136(3):314-326. doi: 10.1161/CIRCULATIONAHA.116.025290. PMID: 28716832.
Link to Article
Link to FULL FREE PDF

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