Why do certain tests require cooling

The early induction of brain hypothermia, within three hours, is most effective because epinephrine, a trigger factor in these changes, is released in high concentrations immediately after injury. Enabling emergency medical services personnel to minimize the time lag between injury and hypothermia treatment to less than three hours after injury is critical to the efficacy of this approach.

Research indicates that even with early induction of brain hypothermia, the duration of treatment should be between three and seven days, depending upon the severity of brain damage.

Once the hypothermia treatment is complete, careful and gradual rewarming is a necessity for safe treatment. Thermal management for neonatal encephalopathy is referred to as brain hypothermia. In localized skin cooling, cooling the core temperature of the patient is undesirable; it is preferred that the skin be cooled locally to achieve a variety of desired effects.

In a manner similar to that used in hypothermia treatments, a liquid chiller and cooling pads are often used to achieve the desired heat transfer. Skin cooling has been applied with good effect in cancer patients see Figure 1. It is widely known that hair loss is a side effect of chemotherapy treatments and can have a traumatic impact on patient emotional well-being.

By cooling the scalp both during and after chemotherapy treatment, hair loss can be reduced. By placing cold scalp caps on the patient, the vessels in the scalp are cooled, and the capillaries that carry the chemotherapy vasoconstrict.

This vaso-constriction reduces the blood flow to the area, and the low temperature reduces the reaction of the chemotherapy treatments with the hair follicles. The end result is that the damage to hair follicles is significantly reduced, mitigating or reducing hair loss. Some studies have shown that thermal therapy is effective for stroke patients focused on upper limb functional recovery.

Known as thermal stimulation, it has shown to enhance sensory and motor function recovery. The key seems to be the activation of motor and sensory function at the same time.

Biological and chemical reagents are employed to identify and measure a target substance by laboratory and medical technicians. In biotechnology, reagents have been used to identify and manipulate chemical matter in cells.

Reagents may be a compound or a mixture. In organic chemistry, most reagents are small organic molecules or inorganic compounds. Whether a compound, mixture, or organic molecule, most reagents share a common characteristic — they are susceptible to heat and thermal cycles. Reagents have a narrow thermal window for storage and use, which requires precise temperature control.

Biotechnology reagents are particularly affected by heat. Precise thermal management below ambient increases the shelf life of reagents, reducing reagent replacement costs and ensuring the accuracy and reliability of laboratory or medical tests. Different reagents used in chemical and biological processes react differently to storage temperatures. Reagent storage systems have different requirements depending on the specific reagent and the storage time.

These storage systems are generally classified into five types based on temperature range control:. In this application note, we will focus on compressor-based temperature control for reagent storage refrigerators. Within this temperature range, reagents tolerate minor temperature changes.

However, some reagents are more sensitive and will start to break down after only a few of these minor temperature swings. Precise temperature control is one of many designs challenges OEMs face when developing reagent storage systems. Size, weight and power SWaP requirements play a significant role in the design and manufacturing of reagent storage equipment.

Other challenges include minimizing the operating noise level, managing the airflow within the cooling system, preventing condensation inside the chamber and activating temperature alarms if control is not properly maintained. Using eco-friendly, government and industry approved refrigerants is also vital for compressor-based systems to ensure future-proofing of the system.

Miniaturization of equipment to free up laboratory space is as prevalent as ever. This includes reducing the physical size of reagent storage equipment without reducing the storage capacity. This is often achieved by packing more reagents into a smaller space, which could result in a higher thermal load to the unit and a more obstructed path for chilled air to reach the reagents. To meet the required cooling capacity in a more compact form factor, refrigeration systems must have a high coefficient of performance and utlize components that will achieve the desired results.

In order to increase performance while reducing power consumption and noise level, waste heat must be managed and dissipated efficiently. In these cases, one solution is to use a product like a heat pipe to move and spread the heat from the electrical component to a larger surface area far from the immediate contact surfaces. Heat pipes are essentially superconductors of heat along a path defined by the geometry of the pipe.

If we imagine a surgical device with a very localized heating zone at the tip and a relatively long handle with no heating, it is apparent that without heat spreading, the tip of the device and the surrounding area will become very hot relative to the rest of the device. A solution for this application would be to add a heat pipe to the design to transfer a portion of the energy generated at the tip of the device and spread it evenly throughout the handle to maintain a stable, safe, and uniform temperature profile across the whole device.

As a final note about temperature requirements, it is worth discussing applications that require precise temperature control. These applications often involve lasers or sensitive electronics that operate best within a relatively small temperature window.

With only a slight temperature difference between the cooling medium air in the room and the component, a refrigeration system is often required to achieve cooling temperatures below the ambient temperature in the room.

Lower-powered applications can utilize thermoelectric devices a. TECs or Peltier Coolers to achieve precise temperature control and high reliability. Alternatively, temperature control can be achieved using a liquid cooling system and a vapor compression-based chiller to achieve colder than ambient temperatures.

Often when discussing the power dissipation of a component, engineers will talk in terms of steady-state performance. However, there are a significant number of applications that require a more transient approach to the problem. Consider a medical device that operates at full power for 1 minute and then sits idle for the next 10 minutes as its standard operating cycle.

If an engineer were to treat the heat dissipation from this device as a steady-state condition, the cooling system would wind up being sized for 10 times more power than is likely needed. Each additive affects blood sample testing and storage in different ways.

For example, hematology procedures often require the blood to remain in the tube until the anticoagulants stabilize. Depending on the sample use, one of three temperatures will typically be specified for blood sample storage: room temperature, refrigerated, or frozen. Blood used for certain molecular genetic tests can remain stable for many days, with a wide range of acceptable temperature. DNA remains stable at room temperature for up to a month, but because live blood cells begin dying within two days, samples should be cultured or frozen in liquid nitrogen for future use.

Blood banks consider six weeks to be the "shelf life" of blood, but a study from Johns Hopkins University has shown that after three weeks, red blood cells are less effective at delivering oxygen-rich cells throughout the body. Blood stored longer than three weeks becomes less flexible and less able to fit in the body's smallest capillaries.

Depending on the blood's future use, longer storage without refrigerated or frozen temperatures can jeopardize its viability. For example, if stored blood is used in a transfusion, the blood never regains the flexibility that it lost after the three-week mark unrefrigerated in storage.