Dialysis serves as an artificial replacement for failed kidney function, primarily by filtering waste products and removing excess fluid from the blood. Missing a scheduled dialysis session means that the essential filtration and balancing mechanisms are abruptly halted, allowing toxins and fluid to accumulate unchecked. Even a single missed treatment can rapidly lead to a dangerous buildup of substances in the bloodstream, creating conditions that can quickly become life-threatening.
Accumulation of Waste Products and Fluid
The immediate consequence of missing dialysis is the uninterrupted accumulation of metabolic waste products, which the kidneys are no longer able to excrete. Nitrogenous wastes, such as urea and creatinine, begin to build up in the blood, a condition known as uremia. This toxic environment affects multiple body systems, often resulting in symptoms like severe fatigue, persistent nausea, and vomiting. The buildup of these substances can also lead to confusion and a significant loss of appetite.
Fluid retention, or volume overload, is another immediate and serious effect, as the patient’s body retains all the water and salt consumed since the last treatment. This excess volume exerts pressure on the circulatory system, leading to noticeable peripheral edema, particularly swelling in the ankles, legs, and hands. Weight gain between sessions is a direct measure of this retained fluid.
The most severe danger from volume overload arises when this fluid backs up into the lungs, causing pulmonary edema. Since the heart cannot efficiently manage the massive fluid volume, pressure increases in the blood vessels surrounding the lungs’ air sacs. This causes fluid to leak into the lung tissue, leading to severe shortness of breath (dyspnea) and a feeling of drowning. This shortness of breath is a medical emergency that indicates significant strain on the heart muscle.
Risk of Acute Electrolyte Imbalance
The most acute and potentially fatal risk from a missed dialysis session stems from unchecked changes in blood chemistry. Dialysis is specifically designed to maintain safe levels of minerals, and without it, certain electrolytes can spike to dangerous concentrations. The most concerning of these is potassium, leading to a condition called hyperkalemia.
Potassium is an electrolyte that regulates the electrical signals necessary for nerve and muscle cell function, including the heart muscle. When potassium levels become excessively high, the electrical stability of the heart is compromised, interfering with its normal rhythm. This can trigger irregular heart rhythms, or arrhythmias, which may manifest as palpitations, a fluttering feeling in the chest, or sudden, severe chest pain. An uncontrolled rise in potassium can rapidly progress to ventricular fibrillation, which leads to sudden cardiac arrest and death.
The body also rapidly develops metabolic acidosis because the failing kidneys cannot excrete hydrogen ions, which are acids. The blood becomes increasingly acidic, which further worsens the effects of hyperkalemia and impairs organ function. Symptoms of this acid buildup include a profound sense of fatigue, confusion, and changes in breathing patterns, often characterized by rapid, deep respirations as the body attempts to compensate by blowing off carbon dioxide. The combination of uremia, hyperkalemia, and severe acidosis creates a highly unstable state where muscle weakness becomes profound, signaling a systemic crisis.
Immediate Action Plan
If a dialysis session is missed, the patient or caregiver must immediately contact the dialysis clinic or the attending nephrologist. The purpose of this call is to inform the medical team of the missed treatment and to arrange for an urgent, make-up session as quickly as possible. Waiting until the next regularly scheduled appointment is highly inadvisable, as the body’s internal balance can deteriorate rapidly within hours.
Should the patient experience any severe, sudden symptoms, immediate activation of emergency medical services (911 or local equivalent) is necessary. These severe indicators include the inability to catch a breath, the onset of severe chest pain, new or worsening confusion, or an irregular or pounding heart rhythm. These signs often reflect life-threatening complications, such as acute pulmonary edema or severe hyperkalemia, which require immediate hospital-level intervention.
Patients should not attempt to manage symptoms at home through restrictive dieting or fluid restriction alone, nor should they wait for their clinic to call them back if severe symptoms are present. The medical team will determine the safest course of action, which may involve immediate transport to an emergency room for urgent treatment and stabilization. Prompt communication and emergency action when a session is missed are the next lines of defense.