Kids Kidney Research

Patients on dialysis have a very high risk of developing heart and vessel (cardiovascular) disease. In 20-30 yr olds, the chance of dying from cardiovascular disease is the same as that of an 85yr old.

Haemodialysis (HD) places a lot of strain on the heart. It can result in a drop in blood pressure (BP) and symptoms such as headaches and stomach cramps. A low BP is a signal for the heart to work harder to deliver blood to all the organs in the body. The heart itself requires blood to work normally. If its blood supply falls below a critical level this injures the heart muscle (myocardial ischaemia). Injured heart muscle segments are unable to move (contract) normally, thereby reducing overall function. Adults develop myocardial ischaemia during HD. If this results in a temporary reduction in heart function, we refer to this as myocardial stunning. Repeated episodes of myocardial stunning can cause myocardial hibernation, where ‘hibernating' segments of the heart have a permanent reduction of function.

Unlike adults, children do not have coronary heart disease, namely significant blockages in vessels supplying the heart. Despite this they are prone to myocardial ischaemia. It has been shown that children on HD develop myocardial stunning and the amount of stunning is related to intradialytic BP changes. Encouragingly, adult studies have shown that myocardial stunning can be reduced by cooling the solution (dialysate) that is necessary for HD. This method can be easily adopted by all HD units and if the reduction in temperature is judged correctly it has the added value of a more comfortable HD session for the patient.

The aim of this study is to determine: 

1.        Whether cooling the dialysate improves BP and reduces myocardial stunning in children on HD

2.        The optimal dialysate temperature that will benefit the heart by reducing myocardial stunning and also improve children’s symptoms on HD

All patients will start with HD using the standard dialysate temperature of 37°C. During this time baseline measurements will be taken. Children will then randomly allocated to Group A or B. Group A patients will be dialysed against a temperature that is equal to the child’s body temperature as measured by their temperature taken by a tempadot in the mouth (isothermic dialysate) and Group B against the patient’s tempadot temperature minus 0.5°C (cooled dialysate). After 2 weeks at the new temperature, the patients’ heart function during the HD session will be monitored in both groups. Both sets of patients will then return to a dialysate temperature of 37°C for 2 weeks. After this time another set of measurements will be taken before the patient crosses over to the other group. Therefore Group A patients will then be dialysed against cooled dialysate and Group B against isothermic dialysate. Again after 2 weeks at the new temperature, the patients’ HD session will be monitored in both groups.

At each stage of the study heart function will be measured using non-invasive ultrasound measurements at the start and end of the monitored HD session. In addition the patient’s heart rate, BP and any symptoms they are experiencing throughout their HD treatment will be recorded by the investigator. Each child will also be interviewed at the end of their monitored HD treatment to assess the ‘quality’ of their dialysis treatment, namely questions to see if they developed any symptoms of low BP and, more particularly those related to feeling cold. 

Cooling the dialysate is an option that is available to all UK centres. If this is found to be of benefit in reducing the cardiovascular stress of HD the potential is that the means of reducing negative cardiovascular events and death in these young patients has been identified, giving them healthier hearts for their adult lives.