Targeted Temperature Management (TTM), also known as therapeutic hypothermia, is a critical intervention aimed at reducing brain injury following cardiac arrest or ischemic events by carefully lowering body temperature. Among various TTM methods, non-invasive cooling pads offer a safer, easier-to-manage alternative compared to endovascular devices and cold fluid infusion. While endovascular cooling provides rapid temperature control, it carries risks such as infection, bleeding, and the need for highly skilled professionals. Cold fluid infusion can cause electrolyte imbalances and potential fluid overload. Non-invasive pads, on the other hand, are straightforward, cost-effective, and avoid invasive complications, making them suitable for prolonged TTM therapy. This review compares the advantages and limitations of each approach, with a focus on the benefits of non-invasive cooling pads for maintaining safe and effective therapeutic hypothermia.
Targeted Temperature Management (TTM) therapy, also known as therapeutic hypothermia, involves lowering and maintaining a patient’s body temperature to improve outcomes after cardiac arrest or other brain oxygen deficiency situations (e.g. ischemic strokes, neonatal HIE). Several technologies and methods are employed to perform a TTM therapy. Surface cooling devices, endovascular cooling devices and cold fluid infusion are the most popular of these methods.
Of course, the most important aspect is to carry out the therapy and cool down the patients who qualify for it. However, it remains an open discussion about the choice of method. Below we will discuss the pros and cons of the available solutions.
Surface cooling devices
Blankets, vests, head coverings (such as TrueCool hypothermia device), are pads of various sizes and shapes that cover the patient, and in which cooled water circulates. These non-invasive pads are straightforward to apply and do not require invasive procedures, making them accessible to a wider range of healthcare providers. There is no risk of complications such as infections or vascular injuries associated with invasive methods. Compared to endovascular cooling systems, these devices are often more cost-effective, requiring less specialised equipment and fewer consumables. Pads can be adjusted easily to ensure consistent cooling across different parts of the body. They can also be repositioned as needed to accommodate patient movement and comfort.
The efficacy of surface cooling may be however limited by factors such as body insulation, ambient temperature, and patient size.
Endovascular cooling devices
This solution involves the insertion of a cooling catheter into a large vein. Endovascular cooling provides efficient and rapid cooling of the core body temperature by directly cooling the blood. However, one should consider whether the speed of cooling using this method compensates for the risks that come with it.
Inserting a catheter into a large vein poses risks such as infection, bleeding, vascular injury, thrombosis, and catheter-related bloodstream infections (CRBSIs). The procedure requires skilled healthcare professionals to insert and manage the catheter, which may not be available in all settings. Endovascular cooling systems are generally more expensive than surface cooling devices, both in terms of initial investment and ongoing maintenance.
The use of catheters and other specialized consumables adds to the cost, and more than that, the invasive nature of the procedure increases the risk of infections, which requires stringent aseptic techniques and careful monitoring.
Cold fluid infusion
Cold infusions can cause changes in electrolyte levels, especially if not monitored closely. This is particularly relevant for electrolytes like potassium and sodium, which can lead to complications such as arrhythmias. Using large volumes of infusion fluids can lead to fluid overload, particularly in patients with compromised cardiac function, potentially resulting in pulmonary edema.
American Heart Association (AHA) Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care and European Resuscitation Council (ERC) Guidelines for Resuscitation: both recognize the role of using cold infusion fluids in the initial phase of TTM therapy. Both organizations emphasize as well the potential risks of using cold fluid infusion method such as hemodynamic instability, electrolyte disturbances, and potential complications.
The same two organizations suggest using surface cooling devices or intravascular cooling catheters for maintaining the target temperature in post-cardiac arrest patients.
Non-invasive cooling pads, in the case of therapies lasting longer than 24 hours, are equally effective as intravascular cooling catheters in achieving and maintaining target temperatures while offering a safer and more comfortable alternative with fewer complications, such as infection and bleeding, associated with invasive methods. This makes non-invasive cooling pads a preferred choice for TTM due to their ease of use and lower risk profile.