Cardiac Monitor vs. In Vitro Diagnostics: An Edwards Lifesciences Industry Perspective

If you only skim the Edwards Lifesciences website, you might think it is mainly about transcatheter heart valves. That’s the story that gets the headlines. But if you want to understand the Edwards Lifesciences industry more fully, there is another thread that matters to me almost every day: critical care and hemodynamic monitoring.

I’m an ICU physician. I’m one of the people called when a patient is no longer following the expected path. In that role, triage is really a question of time: how many minutes do we have, can what we want to do fit inside that window, and what is the worst consequence if we act too late?

That is why the question “What is in vitro diagnostics?” keeps coming up in clinical conversations. The U.S. Food and Drug Administration describes in vitro diagnostics as tests done on samples such as blood or tissue taken from the human body. The sample is sent somewhere else and analyzed outside the body. A cardiac monitor is a different category. It does not wait for a sample to travel to a lab. It creates a continuous signal from the patient in real time.

The comparison that follows is not a claim that continuous monitoring should replace laboratory testing. It is a comparison of two different ways to see what is happening to a patient, and it is meant to help teams stop treating them as if they were the same kind of purchase, the same kind of data, or the same kind of clinical answer.

What This Comparison Is Really About

When I compare continuous cardiac monitoring with in vitro diagnostics, I’m comparing a live feed with a photograph. An IVD can be a very good photograph. It can show a troponin elevation, a potassium of 6.8, or a lactate that has been climbing over several hours. It is often precise, standardized, and extremely useful. But it is always a picture from the past. A continuous monitor is the part that tells you whether the patient is still moving in the wrong direction at the moment you are looking.

That doesn’t mean the monitor replaces the lab. It means they answer different questions.

Dimension 1: How Soon Does the Answer Arrive?

Time is the dimension with the clearest winner. Continuous monitoring answers every few seconds. A cardiac monitor with an arterial pressure signal can show a falling mean arterial pressure, a rising heart rate, or a narrowing pulse pressure within the same heartbeat. An IVD is constrained by sample transport and analyzer time. Even a STAT blood gas takes minutes, and many important IVD results take 30 to 60 minutes from the moment the sample is drawn. Some tests are batched, which takes even longer.

In March 2024, I was called about a patient whose nurse noticed urine output had slowed over three hours. The blood gas drawn 40 minutes earlier was stable. The monitor showed a narrowing pulse pressure and an upward heart-rate trend. By the time a second lab result came back, we had already started the resuscitation. The lab later confirmed the problem, but the monitor is what made us act early enough.

This is also where an infusion pump fits into the story. An infusion pump can deliver vasopressors reliably, but the pump alone is not a feedback system. If the patient’s pressure is dropping, the pump will keep delivering the same dose until someone changes it. The cardiac monitor is what supplies the feedback. Without that signal, you are adjusting treatment by guesswork.

Dimension 2: What the Result Actually Tells You

IVDs are strong at identifying molecular and cellular facts. A high-sensitivity troponin tells you whether cardiac muscle has been injured. A lactate trend tells you whether there is a mismatch between oxygen delivery and oxygen consumption. A blood gas tells you about ventilation, acid-base status, and electrolytes at a single point in time.

Continuous hemodynamic monitoring is not trying to replace those facts. It is trying to characterize the system that delivers oxygen to tissue: blood pressure, cardiac output, stroke volume variation, pulse pressure variation, and central or mixed venous oxygen saturation. These values describe flow and pressure as they are happening.

When I see a patient with respiratory distress and a new troponin rise, the IVD tells me cell injury has occurred. The monitor tells me whether the circulation is compensating or failing. Both facts matter. If you remove one, you can still make a reasonable decision, but you are making it with a missing piece of the picture.

This is where I reversed my own early assumption. When I was a trainee, I thought of tests as either “real” lab tests or “noisy” bedside signals. It took me about four years and a lot of decompensating patients to understand that the distinction was not real versus noisy. It was precise but delayed versus continuous but messy. Sometimes you need the precision. In an emergency, you often need the continuity more.

Dimension 3: Reliability, Artifacts, and Context

Let me be direct: continuous monitors can produce bad numbers. An arterial line can have a damped waveform, a drift in zero reference, or artifacts from patient movement. The monitor is not magic. It needs proper set-up, calibration, and interpretation.

In vitro diagnostics also produce errors. Hemolyzed samples, labeling mistakes, and patient-specific interferences can create a misleading result. A normal lactate can be absent if the sample sat too long before analysis. A high potassium can be the result of a difficult draw rather than a true metabolic emergency.

Here is the lesson that still surprises residents: when the monitor and the laboratory tell conflicting stories, do not automatically trust the one with the most precise-looking number. Verify the waveform. Reposition the transducer. Repeat the sample. Make a clinical judgment. In an emergency, the question is not which device looks more accurate in a brochure. The question is which signal is reliable in this patient, right now.

Continuous monitoring also creates alarm fatigue. I don’t have hard data on the true-to-false alarm ratio in every unit, but I can tell you anecdotally that an unmanaged monitor is worse than no monitor. The technology needs a protocol, not just a purchase order.

Dimension 4: Cost and Total Burden

If you are responsible for a budget, the base cost of an IVD test can look lower than the cost of a monitoring system. But total cost is not the same as list price.

Every time you draw an IVD sample, you pay for phlebotomy, transport, reagents, analyzer time, and result review. Repeat that often enough across a long ICU stay, and the cumulative cost becomes real. Patients who receive too many blood draws can also develop hospital-acquired anemia. This is not an argument against phlebotomy. It is an argument for thinking about what each source of information actually costs over the whole illness.

I’m not going to give you a dollar amount, because I don’t have access to your hospital contract prices. What I can say from experience is that in an unstable patient, the extra cost of continuous monitoring behaves like a rush fee. You are paying for time certainty. In urgent critical care, the cost of missing a deterioration event is usually much higher than the cost of the sensor or the system. That equation is why certainty is worth paying for.

This approach worked for us because we were using monitoring for a selected high-risk population, not for every bed in the hospital. If you put continuous monitors on every low-risk ward patient, the cost grows and the alarms become noise. Your situation may be different. The technology needs to be matched to the acuity.

Scene-Based Recommendations

So when should each approach win? Here is the honest, scene-based answer:

• For an unstable patient who is on vasopressors through an infusion pump, use continuous cardiac monitoring as the primary safety loop. Use serial IVDs to understand the cause: infection, ischemia, bleeding, or metabolic disturbance.
• For a relatively stable patient who needs a diagnostic answer, such as chest pain with normal hemodynamics, start with the IVD. A troponin result will help confirm or exclude injury, and a continuous monitor may not change the immediate decision.
• For a patient receiving fluid resuscitation in shock, use continuous response markers when available—pressure, flow, stroke volume variation—and confirm the clinical direction with IVD markers like lactate over the following hours.

The Bottom Line

The deeper point is not that one technology is superior to the other. It is that they measure two different kinds of time. In vitro diagnostics measure a specimen that has left the body. Continuous monitoring measures a patient who is still trying to live.

If you have spent time on the Edwards Lifesciences website, you have probably seen the emphasis on structural heart innovation. The critical care side of that company’s history is quieter, but equally relevant: it is about reducing the gap between a change in the patient and a change in action. For a patient in shock, that gap is everything.

In my opinion, that is the right lens for monitoring decisions. The question is not “can we afford a little more monitoring?” The question is “what is the cost of acting on information from 30 minutes ago?” When you frame it that way, many budget decisions become clearer, especially in the moments when the answer cannot wait.