Target values provide guidance, but ICU care remains personalized

She compares it to driving a car: “The most important thing is that you stay in the correct lane, within your own lane. If you drift too far to the left, you risk a collision with oncoming traffic, but if you go too far to the right, you drive into the ditch. Still, you can’t always just drive straight ahead. Sometimes an accident happens, forcing you to adjust your course.”

For her PhD research, Van der Wal, researcher and anesthesiologist in training, investigated the ideal values within ICU guidelines for oxygen therapy, anticoagulation, and pain management. The goal was to tailor treatments more effectively and safely to each patient.

Anticoagulant treatment

During the COVID-19 pandemic, she studied the use of the blood thinner heparin in COVID patients. She found that the drug was effective in properly treating blood clots (emboli) in their lungs, but also that a higher dose than the maximum prescribed value was needed for a good result.

According to Van der Wal, this shows that the ICU must always critically review previously set standards. “The message is that we should not blindly trust what was established in the past. We need to be willing to continuously reconsider target values and ask ourselves: do these values still hold? Especially when a new disease emerges, like COVID-19.”

Pain management

Another important aspect of ICU care is pain management. The amount of painkillers given to patients varies. There is, however, a minimum and maximum limit. Van der Wal explains, “Too many painkillers can cause patients to remain on ventilation longer because painkillers suppress the respiratory drive. Meanwhile, too few painkillers can trigger an additional stress response, which activates inflammatory and coagulation reactions, impairing recovery.”

According to Van der Wal, the goal is to give patients just enough pain medication so they spend less time in the ICU while remaining comfortable. But how do you determine how much pain relief a patient who is artificially sedated and cannot indicate whether they are in pain should receive? She uses a car analogy again: “When there’s a problem with your motor oil, a warning light comes on in your car. But if you don’t start the car, no signal is given that there’s a problem. It’s similar for patients who are artificially sedated in the ICU: they can’t signal that they’re in pain.”

She researched a new device (the Nociception Level Monitor, or NOL monitor) that can assist doctors in determining pain medication for ventilated patients. This device combines various measurements and predicts whether a patient will experience pain. It was previously used in the operating room at LUMC with promising results: patients had less pain and needed fewer opioids.

Van der Wal tested the device in the ICU but concluded that the tool was not yet suitable for standard use on her ward. “IC patients are very ill. They often have an abnormal heart rhythm compared to healthy patients. The device needs to be adjusted for this. It also requires longer-term testing in a large study before we can implement the monitor in the ICU.”

Oxygenation

The third part of her research concerns oxygen therapy, another crucial pillar of ICU care. Many ICU patients are too weak to breathe deeply and effectively on their own. They receive oxygen via a breathing tube, which takes over their breathing. Very ill patients need a lot of oxygen to help their bodies process disease. But again, it’s a fine balance: too much oxygen is toxic, while too little oxygen can damage tissues.

Van der Wal wanted to know what the ideal oxygen level is within target values for patients. “We compared two groups receiving low and high target oxygen levels, but found no difference in health outcomes between the groups. Unfortunately, we had to stop the study halfway due to the outbreak of COVID-19.”

Still, the study was not in vain. “We now know that we should primarily focus on the individual rather than look for a one-size-fits-all approach. For example, when administering oxygen, we often aim for a value of about 12 kilopascals, as this is the average oxygen pressure in human blood. But not every patient can reach this value because diseased lungs or other problems prevent adequate oxygen uptake. In that case, striving for 12 makes no sense. Instead, we should consider what is feasible for each patient.”

Guidance

Determining ideal target values in the ICU is complicated by differences in diseases, disease severity, and individual patient variations, Van der Wal concludes in her thesis. Her research shows that target values provide valuable guidance, but that it is safe to deviate from them when the situation demands it.

Imeen van der Wal obtained her PhD on April 4th at the Faculty of Medicine/LUMC of Leiden University. Her supervisors were Prof. Dr. E. de Jonge, Dr. H.J.F. Helmerhorst, and Prof. Dr. A. Dahan. You can find the publication of the dissertation here.