Chills, medically known as rigors, are a common and often distressing experience for individuals undergoing hemodialysis. These chills manifest as uncontrolled shaking and shivering, which can be caused by a drop in core body temperature or, more seriously, by an underlying medical issue like an infection. While the dialysis process is designed to remove waste and excess fluid, it can also disrupt the body’s thermal regulation and expose the patient to potential contaminants. Prevention strategies range from simple environmental adjustments to complex machine parameter modifications and strict infection control protocols.
Environmental and Comfort Adjustments
The physical environment of the dialysis unit plays a significant role in patient comfort and can directly contribute to the onset of chills. Dialysis centers are often kept cool to offset the heat generated by the numerous machines and the activity of the staff. Patients, however, remain seated for several hours, which limits their heat production and makes them more susceptible to cold.
Patients can take immediate action by wearing warm, layered clothing to their appointments. Items like a warm hat, gloves, and thick socks are particularly helpful, as heat can be lost quickly from the head and extremities. Bringing a blanket or requesting an extra one from the staff can also significantly help maintain body warmth during the session. It is important to note that the vascular access site, whether a fistula, graft, or catheter, must remain visible to the clinical staff for safety monitoring.
Patient positioning within the facility can also be a factor, as sitting directly under an air conditioning vent can increase exposure to cold drafts. Requesting a chair location away from direct airflow or exterior doors can help minimize unwanted cooling. Some manufacturers offer specialized clothing designed for dialysis patients that provides warmth while allowing easy access to the treatment site.
Adjusting Dialysis Parameters for Thermal Stability
The dialysis machine itself influences the patient’s thermal state through the temperature of the dialysate, the fluid used to filter the blood. The blood flowing through the machine exchanges heat with the dialysate before being returned to the body. Conventionally, the dialysate temperature is set around 37°C (98.6°F) in an attempt to match the patient’s core body temperature.
However, even a dialysate temperature of 37°C can sometimes cause a slight increase in the patient’s core temperature. This thermal gain can trigger a natural response called vasodilation, where blood vessels near the skin surface widen to release heat. This vasodilation can lead to a drop in blood pressure, and paradoxically, the subsequent efforts to correct the temperature can result in a chill. The physiological difference between the threshold for skin vasodilation and the onset of shivering is very small, often only 0.3°C to 0.8°C.
A technique known as thermoneutral or cooled dialysis involves setting the dialysate temperature lower, typically in the range of 35°C to 36°C, or often 0.5°C below the patient’s resting core temperature. This slight cooling prevents the core temperature from rising, which improves hemodynamic stability and can reduce the incidence of intradialytic hypotension. While this cooled dialysate can sometimes cause discomfort and even shivering in some patients, it is a clinically proven method to avoid the heat-related physiological stress that can precede chills. Furthermore, the rate of ultrafiltration, which is the removal of excess fluid, can also affect thermal stability; rapid fluid shifts can sometimes lead to blood pressure drops that manifest as chills.
Protocols for Preventing Contamination and Infection
The most concerning cause of chills and rigors during dialysis is an infection or a pyrogenic reaction, which is the body’s response to bacterial byproducts like endotoxins. These reactions can be a sign of a bloodstream infection, which requires immediate attention. Preventive measures focus on maintaining a sterile environment and preventing the entry of contaminants into the patient’s circulation.
Strict adherence to hand hygiene by both staff and patients is a fundamental requirement before accessing the vascular site. Staff must follow rigorous sterile techniques when cannulating the fistula, graft, or catheter, as the access site is a potential entry point for bacteria. This includes thorough cleaning and disinfection of the access site before needle insertion. Catheters carry the highest risk of infection, making meticulous care and the “scrub-the-hub” protocol for the catheter ports essential.
The quality of the water used to create the dialysate must be continuously monitored, as contaminated water or dialysate can introduce endotoxins and bacteria into the blood. Dialysis facilities must meet stringent standards for water treatment and equipment sterilization, including the proper disinfection of the dialyzer and tubing between uses. Patients should immediately report any signs of a potential access site infection, such as redness, swelling, pain, or drainage, to their healthcare team before their treatment begins.