SCCM Resource Library-Invasive Hemodynamic Monitoring

Video Transcription

Good morning. My name is Anne Gage. I'm an interventional cardiologist and a cardiac critical care provider.  Today I'm going to be discussing invasive hemodynamics in cardiogenic shock. Before we begin, I have nothing to disclose relevant to this presentation.  The objectives for today's presentation include recognizing the capabilities and technical  limitations of invasive hemodynamic monitoring in the evaluation of critically ill patients with shock.  We will also choose among invasive and non-invasive hemodynamic monitoring methods in different clinical settings.  And hopefully we will improve our clinical diagnostic skills and recognize when these skills alone may suffice to make therapeutic decisions.  There are multiple forms of hemodynamic monitoring that show promise in the management of cardiogenic shock.  These options include arterial lines, pulmonary artery catheters, biomarker measurement, and serial echocardiography.  Dr. Wiley has reviewed the use of ultrasound in shock monitoring. I am now going to focus on the use of the arterial line and the pulmonary artery catheter,  which can also be known as the PA catheter, a right heart cath, or a SWAN. Peripheral arterial catheterization, commonly known as an A-line, is a common form of invasive  hemodynamic monitoring well known to this audience. Arterial lines allow for continuous monitoring of systolic blood pressure and mean arterial pressure.  This facilitates easy and frequent titration of vasoactive medications or inotropes in shock patients.  We know that blood pressure can vary with the stage of cardiogenic shock, but basic consensus definitions include hypotension as a core component of the definition of cardiogenic  shock. Hypotension in these definitions is variably defined, but usually meets either one of the  following criteria, systolic blood pressure of less than 90 millimeters of mercury, a map of less than 60 millimeters of mercury, or a map greater than 30 millimeters of mercury  less than the patient's usual baseline. This is also accompanied by tissue hypoperfusion. To this end, multiple studies have shown a lack of correlation of non-invasive and invasive  blood pressure monitoring under various clinical conditions. Sidlerova et al. examined 85 patients hospitalized for cardiogenic shock.  Blood pressure was measured every six hours for the first 72 hours of hospitalization, with each set of measurements including two invasive blood pressures, two osculatory blood  pressures, and two oscillometric blood pressures. Sidlerova et al. demonstrated that in patients with cardiogenic shock, non-invasive measurements  of systolic blood pressure are often inaccurate compared to invasive measurements of systolic blood pressure.  They specifically found that non-invasive methods overestimate blood pressure in hypotensive patients.  Similarly, Lehman et al. retrospectively examined invasive arterial blood pressure and non-invasive blood pressure measurements in a large ICU database.  They found, again, that non-invasive blood pressure is greater than invasive blood pressure  during periods of hypotension and that non-invasive blood pressure is lower than invasive blood pressure in patients who have hypertension.  Notably, these authors did find a good agreement between non-invasive MAP and invasive MAP. I believe this finding is clinically significant.  In the initial management of shock, we rely on non-invasively measured blood pressures. This is obvious.  It's before our suspicion has been raised and before other methods such as an invasive monitor would be placed.  Therefore, in patients with relatively normal non-invasive blood pressure, but with clinical signs of hypotension, we should be alert to a false sense of security.  The data that I just presented tells us that we must be aware that real blood pressure values could be very different than what we're being lulled to believe by the non-invasive  blood pressure, and we may actually overlook an important diagnosis. Thus, if arterial pressure values really need to be accurately measured, invasive monitoring is recommended.  I want to mention this study that I found to be very interesting as I was reviewing the literature for this presentation.  This is a large study in the anesthesia literature by Wax et al. They examined almost 25,000 intraoperative cases and found similar findings to Lehman  and Sidlova with respect to higher non-invasive blood pressures during periods of hypotension and lower non-invasive blood pressures during periods of hypertension.  However, they also looked at clinical consequences between patients monitored with only an arterial  line and those monitored with both an arterial line and non-invasive blood pressure. In patients where both non-invasive blood pressure measurements and an arterial line  were used, there was a decreased use of blood transfusions, vasopressor infusions, and antihypertensive medications compared to the arterial line group alone.  This led the authors to postulate that during periods of hypotension, when blood transfusion  or vasopressor infusion may be considered, non-invasive blood pressure tends to be higher  than arterial line blood pressure and reassures the clinician that such intervention may not be necessary.  Similarly, during periods of hypertension, non-invasive blood pressure tends to be lower than that measured by an arterial line, making antihypertensive therapy seem less warranted.  While these may sound like beneficial drugs or treatments to minimize, this is not outcome data.  In our patients with cardiogenic shock, I would suggest that the astute provider should make clinical decisions based on most accurate data available.  In the cardiogenic shock patient, where systolic blood pressure defines the condition and may  lead to more aggressive and more rapid recognition of the disease state, blood pressure measurements should be as accurate as possible.  And since we're talking about a state of hypotension, this should occur via an arterial line.  Different clinical settings will require different forms of hemodynamic monitoring. I'd like to suggest that invasive hemodynamic monitoring via an arterial line should be  considered in the following situations, in addition to those that I just discussed. Arterial lines can facilitate the frequent or rapid titration of medications with less  patient discomfort. If you're going to be using a medication where rapid titration due to a short half-life  is being used, such as for us frequently in a patient with cardiogenic shock, the use of nitroprusside, the patient will have less discomfort if you're titrating your medication  every three to five minutes and using an arterial line rather than using a continuously inflating blood pressure cuff.  Additionally, in some situations when you'll need to follow serial ABGs or serial lactate, a arterial line can decrease the number of sticks in the appropriate setting.  Peripheral arterial catheterization is also absolutely necessary for monitoring for north-south syndrome in VA ECMO patients.  This is beyond the scope of this presentation, but in order to ensure that there is appropriate  cerebral perfusion in patients on VA ECMO, a right radial arterial line is an absolute necessity and this cannot occur via a non-invasive blood pressure measurement.  Lastly, although a minority of patients, a peripheral artery catheter may be helpful for the use of pulse pressure variation in appropriately selected mechanically ventilated  patients, there are certainly times when clinical diagnostic skills may certainly suffice to make the appropriate diagnosis.  Non-invasive blood pressure monitoring in combination with an excellent physical exam will frequently be sufficient for the initial diagnosis of cardiogenic shock patients who  are in stage C or classic cardiogenic shock. These patients typically present with relative hypotension and are cool or cold on exam.  Additionally, they may have elevated jugular venous pressure. When physical exams suggest hypoperfusion with or without volume overload, this should  be enough to raise suspicion for cardiogenic shock and non-invasive blood pressure monitoring may certainly be sufficient to diagnose this condition.  This leads to the second form of invasive hemodynamic monitoring I'd like to discuss today, the pulmonary artery catheter.  I think it's fair to say that no single monitoring device in the history of medicine has created as much enthusiasm and controversy as the pulmonary artery catheter.  Early retrospective registries failed to show benefit of PA catheter use. Subsequently, several randomized control trials reached negative or neutral conclusions.  Seen here is a summary of 10 years of publications, some retrospective analyses and others are  randomized control trials looking at pulmonary artery catheters versus no pulmonary artery catheters in a myriad of patient populations.  Study populations included a wide variety of patients from those with aneurysmal subarachnoid hemorrhage to ARDS patients to general ICU patients.  As you can see in the far column, these studies showed no benefit to the pulmonary artery catheter in all study populations and often the use of the PA catheter was associated  with an increased rate of complications. The bottom study seen here is the ESCAPE trial or the trial that many cite as the historical  downfall of the PA catheter in cardiac patients. The ESCAPE trial randomized patients with severe symptomatic heart failure despite recommended  therapies to therapy guided by clinical assessment only or therapy guided by clinical assessment and the pulmonary artery catheter.  Notably, this was in a reasonably sick patient population. As I mentioned, patients had to have severe symptomatic heart failure despite recommended therapies.  Randomization required at least three months of symptoms despite the use of an ACE inhibitor and diuretics. The patients had to have an LVEF equal to or less than 30%.  Their systolic blood pressure had to be 125 millimeters of mercury or below and the patients had to have at least one sign and one symptom of congestion.  As you can see from the central figure here where the control and the treatment curves are overlaid, the addition of the pulmonary artery catheter to clinical assessment did  not affect the overall mortality or hospitalization. Taken together, the moral of the story is that there is no data to support the routine use of the pulmonary artery catheter.  But wait, as many of you know, the pulmonary artery catheter continues to play a role in the management of cardiogenic shock and mechanical circulatory support.  While the data I just showed supports the lack of benefit for the PA catheter in routine  practice, it is important to acknowledge that the ESCAPE trial excluded patients with cardiogenic shock or patients with prior inotropic support.  As we know, acute decompensated heart failure is not cardiogenic shock. To this point, the PA catheter has never been studied explicitly in the setting of cardiogenic shock.  So, while we noted the lack of benefit of the PA catheter in routine use, there is recent data to suggest that there may be benefit to this form of invasive hemodynamic monitoring  in the cardiogenic shock population. A recent observational study integrating these various forms of hemodynamic monitoring with  a multidisciplinary diagnostic and therapeutic team, known as the SHOC team, approached, in this study shown here on the left, showed improvement in 30-day survival rates from  47% pre-intervention, that was the average here, 47%, to 77% 30-day survival rates after two years post-implementation.  In this algorithm that I've just told you has prospective data for decreasing the mortality of cardiogenic shock, the first step is the utilization of clinical criteria to identify  a shock state. This seems very appropriate. Recognition should be based on readily available clinical data and bedside assessment.  The next step in data for all patients, though, as you can see here, was right heart catheterization.  This was regardless of whether or not the patient presented with acute decompensated heart failure or whether they came in with cardiogenic shock due to acute myocardial infarction.  You can also see here that the management of all of these patients included serial assessment  of end organ perfusion and hemodynamics with cardiac power output, as well as the pulmonary artery pulsatility index.  Both the CPO and the PAPI require invasive hemodynamic monitoring in the form of a right  heart catheterization and some form of identification of the mean arterial pressure, either through non-invasive monitoring or an arterial line.  Most notably in this study, the use of the right heart cath was associated with a 39% absolute increase in survival.  Shown here is a retrospective registry study examining the outcomes in acute myocardial infarction cardiogenic shock patients treated with an Impella.  In this retrospective registry, the use of invasive hemodynamic monitoring in the form of a pulmonary artery catheter was associated with increased survival.  In patients without hemodynamic monitoring, survival was 49%, whereas survival increased to 63% when invasive hemodynamic monitoring was used.  If you practice in a modern CICU, you know that pulmonary artery catheters are frequently utilized in the treatment of cardiogenic shock.  These catheters are able to confirm the presence and severity of cardiogenic shock. They're also used to assess RV involvement.  The PA catheter can measure pulmonary artery pressures as well as the transpulmonary gradient.  It is able to measure the vascular resistance of the pulmonary and systemic arterial beds.  And a PA catheter can help calculate the cardiac power output and the pulmonary artery pulsatility index, which provide prognostic data in cardiogenic shock.  As of April 2022, I would say, stay tuned. The data for the role of the pulmonary artery catheter in cardiogenic shock continues to emerge.  It is important to remember the pulmonary artery catheter is a diagnostic tool. If it does not improve recognition of a disease state or alter treatment, it will certainly  never impact outcome. However, as our treatment for cardiogenic shock continues to evolve beyond pressors  and inotropes, the use of this diagnostic tool for recognizing shock, determining appropriate support strategies, and titrating treatments very well may end up altering outcome.  Expert opinion in this field is well summarized here. There exists a role of pulmonary artery catheters and the management of patients with cardiogenic  shock for guiding timely initiation, optimization, and when necessary, escalation of medical  and device-based therapies to avoid the onset of end organ dysfunction and hopefully improve early and late outcomes.  I'd like to close with a few words about minimally invasive and noninvasive hemodynamic monitoring.  There are multiple minimally invasive devices that utilize a pulse pressure analysis or a pulse wave analysis derived from an arterial line.  There are also noninvasive forms of pulse waveform analysis, which utilize surface sensors to continuously record the arterial pulse waveform and then use an algorithm to estimate  cardiac output continuously. Other forms of noninvasive cardiac output monitoring include bioimpedance and bioreactance.  Bioimpedance technologies compute cardiac output based on the assumption that thoracic impedance changes over time are proportional to the stroke volume.  Bioreactance devices are a modification of bioimpedance in which phase shifts of an oscillating current are measured as it traverses the thorax.  As you can see from the far column in both of these figures, there are numerous disadvantages and characteristics not suitable for patients with cardiogenic shock.  For example, in some of these, they are inaccurate and severe peripheral edema, hypothermia, shock, severe vasoconstriction, or high doses of vasopressor.  Additionally, some disadvantages may include that they do not work with patients with cardiac arrhythmias or those patients with rapid changes in vascular tone.  Ultimately, a scientific statement from the American Heart Association on the contemporary  management of cardiogenic shock states, although noninvasive devices may be used, their reliability in this setting has not been well studied.  Thank you very much for your attention. I look forward to our panel discussion and the opportunity for some questions.

Video Summary

In this video, Dr. Anne Gage, an interventional cardiologist, discusses invasive hemodynamics in cardiogenic shock. She explains the capabilities and limitations of invasive hemodynamic monitoring and highlights the importance of accurate blood pressure measurements in diagnosing and managing cardiogenic shock. While non-invasive methods can be used initially, she emphasizes that invasive monitoring is recommended for accurate measurement of arterial pressure values. Dr. Gage also discusses the role of arterial lines and pulmonary artery catheters in monitoring and treating cardiogenic shock patients. She explains that while the routine use of pulmonary artery catheters may not show benefit, recent data suggests that they may be beneficial in cardiogenic shock patients. Dr. Gage concludes by discussing minimally invasive and non-invasive hemodynamic monitoring methods and their limitations in patients with cardiogenic shock. She suggests that more research is needed to evaluate the reliability of these devices in this patient population.

Asset Subtitle

Cardiovascular, Shock Non Sepsis, 2022

Asset Caption

Hemodynamics in patients with shock are often complex and can change rapidly as the course of disease evolves and as therapies are initiated. Close monitoring of patients with shock is clearly important, but precisely how to do this remains a subject of great controversy. Years ago, invasive hemodynamic monitoring was common and even routine in some settings, but over time less invasive options have evolved. It remains uncertain whether something has been lost in this shift.

Meta Tag

Content Type Presentation

Knowledge Area Cardiovascular

Knowledge Area Shock Non Sepsis

Knowledge Level Intermediate

Knowledge Level Advanced

Learning Pathway Cardiothoracic Critical Care

Membership Level Select

Tag Hemodynamic Monitoring

Tag Cardiovascular

Tag Cardiothoracic Critical Care

Year 2022

Keywords

Dr. Anne Gage

interventional cardiologist

invasive hemodynamics

cardiogenic shock

blood pressure measurements

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