Dialysis is a procedure that removes waste products and excess fluid from the blood when kidneys are no longer able to perform this function. While life-sustaining, dialysis can lead to complications, one of the most common being intradialytic hypotension (IDH). This sudden drop in blood pressure during treatment requires immediate attention to ensure patient safety and effective dialysis.
Understanding Intradialytic Hypotension
Intradialytic hypotension is defined as a decrease in systolic blood pressure by 20 mmHg or more, or mean arterial pressure by 10 mmHg or more, accompanied by symptoms. Patients might report dizziness, nausea, vomiting, muscle cramps, or faintness. These symptoms arise because the body’s blood pressure drops too low to adequately perfuse organs.
This condition occurs primarily due to the rapid removal of fluid from the bloodstream during dialysis, which can exceed the body’s ability to shift fluid from tissues back into the blood vessels. Other contributing factors include vasodilation, where blood vessels widen, and impaired ability to constrict vessels and maintain blood pressure. Patients with pre-existing conditions like heart disease, diabetes, or autonomic nervous system dysfunction are at higher risk of developing IDH.
The Recommended Patient Position
When a patient experiences intradialytic hypotension, positioning is an immediate intervention. The Trendelenburg position is recommended: the patient lies flat on their back with feet elevated higher than their head. This tilt uses gravity to redistribute blood from the lower extremities towards the core, increasing blood flow back to the heart.
By enhancing venous return to the heart, this position helps increase the volume of blood the heart can pump with each beat, thereby improving cardiac output. This increased output directly contributes to raising blood pressure, helping to restore adequate blood flow to the brain and vital organs. While its universal efficacy is discussed, the Trendelenburg position remains a routine first step in managing IDH episodes due to its physiological benefits.
Beyond Positioning: Other Interventions
Beyond adjusting patient position, healthcare professionals employ other immediate interventions to manage intradialytic hypotension. One action involves reducing or temporarily stopping the ultrafiltration rate on the dialysis machine. This reduces the rate at which fluid is removed from the patient’s blood, allowing the circulatory system to stabilize.
Administering intravenous fluids, such as a saline bolus, is another standard intervention to rapidly increase blood volume and raise blood pressure. Oxygen may also be given to support breathing and tissue oxygenation. For persistent hypotension, medications designed to elevate blood pressure may be administered.
Preventing Future Episodes
Preventing future intradialytic hypotension episodes involves the patient and healthcare team adjusting care. Managing fluid intake between dialysis sessions is important to minimize weight gain, which requires higher rates of fluid removal during treatment. Adhering to dietary recommendations, especially limiting sodium, can help control thirst and reduce fluid retention.
The dialysis prescription can be optimized, including using a slower ultrafiltration rate, adjusting dialysate temperature to be cooler than core body temperature, or modifying dialysate sodium concentration. Adjustments to medication schedules, particularly blood pressure-lowering drugs, may be considered to avoid taking them immediately before a dialysis session. These strategies aim to improve tolerance to fluid removal and maintain stable blood pressure throughout treatment.