Scope

In the United States, in excess of 380,000 patients with renal failure rely on some form of dialysis as life-sustaining renal replacement therapy. More than 90% of these patients are managed with hemodialysis, whereas about 7% use peritoneal dialysis (PD).¹ The most common complication associated with either dialysis modality is infection, although many access site malfunctions and dialysis-related emergencies prompt visits to the emergency department (ED) by this population.

Hemodialysis

Structure and Function

Hemodialysis can be performed through native arteriovenous (AV) fistulas, prosthetic AV grafts composed of polytetrafluoroethylene, tunneled (PermCath) central venous catheters, and nontunneled (temporary) central venous catheters. Different modalities offer different advantages.

Connecting an artery (usually in the forearm) directly to a vein via surgery creates a native AV fistula (Fig. 116.1). Over months, the increased blood flow creates a larger, stronger vein with adequate blood flow for dialysis. Native AV fistulas are less likely than other forms of hemodialysis access to become infected or form clots.

Fig. 116.1 Native arteriovenous graft.

Synthetic AV grafts (Fig. 116.2) are used when forearm veins are unsuitable for native grafts. Synthetic grafts can be used within weeks of placement; however, they have higher infection and clotting rates than native AV fistulas do.

Fig. 116.2 Arteriovenous graft.

Central venous catheters (Fig. 116.3) are used when dialysis access is needed before permanent AV grafts have had time to mature or when fistula or graft surgery fails. Approximately 25% of the hemodialysis patients in the United States use central venous catheters as their primary vascular access. Tunneled, cuffed catheters have a lower infection rate than nontunneled catheters do. All these catheters have a double lumen and are at higher risk for infection and clotting than AV fistulas or grafts are.

Fig. 116.3 Tunneled central venous catheter.

Complications

Infection

Infectious complications are among the foremost causes of morbidity and mortality in hemodialysis patients. The risk for infection results from both impaired immune function related to the renal failure (e.g., altered granulocyte function in uremia) and repetitive access of the vasculature across the protective skin barrier. Vascular access is the source of bacteremia in 48% to 73% of infected hemodialysis patients.²

Clinical findings may include fever, hypotension, altered mental status, skin infection at the access site, and severe sepsis. Patients with diabetes may have ketoacidosis. The differential diagnosis of the various clinical findings in hemodialysis patients is described in Table 116.1.

Table 116.1 Differential Diagnosis of Various Clinical Findings in Hemodialysis Patients

CLINICAL FINDING	DIFFERENTIAL DIAGNOSIS AND CRITICAL ACTIONS
Hypotension	If accompanied by fever, consider sepsis. If sudden onset during dialysis, consider hypovolemia secondary to excessive ultrafiltration, anaphylaxis or anaphylactoid reaction, or air embolism. If accompanied by chest pain, consider tamponade, arrhythmia, or acute coronary syndrome.
Altered mental status	If onset immediately after first hemodialysis session, consider dialysis disequilibrium syndrome. If the onset is gradual, consider dialysis dementia. Infection is a common cause of altered mental status (delirium) in hemodialysis patients, and the presence of a fever should prompt antibiotic administration and a search for the source. Also consider stroke, hypotension, drug effect, seizure, and metabolic derangement (acidosis, hyperkalemia).
Chest pain	Consider acute coronary syndrome, pulmonary embolism, air embolism, uremic pericarditis, and arrhythmias caused by electrolyte imbalance.
Shortness of breath	Consider fluid overload, cardiac tamponade, acute coronary syndrome, air embolism, and anaphylactoid reactions.
Bleeding	Bleeding can be due to excessive anticoagulation during dialysis or uremic coagulopathy.
Fever	Consider line infection in patients with warmth or erythema of the skin overlying the dialysis access site. Consider sepsis if the patient is hypotensive or in shock; obtain blood for culture and administer antibiotics. Fever is almost always due to infection, but overheated dialysate is a potential cause.