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.

Antimicrobial therapy for potential infections related to hemodialysis access (whether catheter or graft) should cover gram-positive species, including methicillin-resistant Staphylococcus aureus (MRSA) and gram-negative species. Gram-positive species account for up to two thirds of cases of hemodialysis access–related bacteremia. Enterococcus and gram-negative rods are also frequently implicated. Broad-spectrum antibiotic coverage should be initiated empirically until the results of culture are available, especially in patients who have a history of gram-negative bacteremia or who may be septic from a secondary source. The recommended regimen is 1 g of vancomycin intravenously (with sequential doses according to the level of the drug at dialysis) plus gram-negative coverage with either an aminoglycoside or a third-generation cephalosporin.

Removal or exchange of an infected catheter is advisable because a bacterial biofilm can form rapidly in the lumens of most indwelling central venous catheters and serve as a source of continued infection. Systemic antibiotics given alone are relatively ineffective in eradicating infection if the catheter is not removed. There are occasional protocols that have demonstrated catheter salvation, but none have done so reliably. Catheter removal with delayed replacement is required in patients who are clinically unstable, who have metastatic infectious complications, or who have tunnel infections.³ Tunneled catheters can be replaced with temporary nontunneled catheters or can be changed over a guidewire, thus avoiding disruption of the patient’s dialysis schedule.

Tips and Tricks

Use of Hemodialysis Graft or Catheter for Emergency Vascular Access

Peripheral hemodialysis access sites may be used for placement of an intravenous catheter in an emergency when no other access is available:

• Do not use a tourniquet.

• Avoid puncturing the back wall of the vessel.

• Use a small intravenous catheter if possible.

• Secure all sources of intravenous access tightly. Infusions may need to be given under pressure because of the relatively high pressure within the peripheral graft.

• Apply firm but nonocclusive pressure for 10 to 15 minutes after removing the intravenous catheter. Ask a nurse experienced in hemodialysis for assistance with removal if available.

• Document the presence or absence of a thrill before and after the procedure.

Central venous hemodialysis access may also be used in an emergency when no other access is available:

• Either the red or blue port may be used because both lead to the vein (even though one is used to withdraw blood during hemodialysis and the other to return it). The “arterial” (red) port is proximal to the “venous” (blue) port to avoid recirculation during dialysis.

• Aspirate at least 2 mL from the port being used because it usually contains heparin between hemodialysis sessions.

• After use, contact a nurse experienced in hemodialysis to clear and prepare the catheter according to standard protocols.

Patient Teaching Tips

Hemodialysis

Keep your access site clean and allow it to be used only for dialysis or emergency access.

Do not allow placement of a blood pressure cuff on your access arm.

Do not lift heavy objects or put pressure on your access arm.

Check the pulse (thrill) in your forearm access graft daily.

Air Embolism

Venous air embolism is a rare complication of hemodialysis that can occur during a session or during insertion of (or more rarely during removal of) a tunneled venous catheter. Air enters the systemic venous system and is transported to the right heart and pulmonary arteries, thereby potentially leading to changes in gas exchange, cardiac arrhythmias, and death.

When air embolism is suspected, 100% oxygen is administered and the patient is intubated if necessary. The patient is placed in the Trendelenburg and left lateral decubitus positions in an attempt to trap air in the apex of the right ventricle and prevent migration to the pulmonary arterial system. Transfer to a hyperbaric chamber should be considered if the patient is stable. If the patient is unstable or suffering arrest, chest compressions may break up the air bubbles—aspiration of intracardiac air should be considered.

Cardiac Tamponade

Many dialysis patients have small pericardial effusions that are not clinically significant. Symptomatic cardiac tamponade can occur in these patients either as a result of an acute pericardial hemorrhage (possibly after heparin administration during hemodialysis) or as an exacerbation of volume overload in the setting of a preexisting effusion. Hemodynamically compromised patients with significant pericardial effusions confirmed by ultrasonography (particularly if right ventricular collapse in diastole is noted) may be treated with emergency pericardiocentesis if they are not sufficiently stable to be transferred for a pericardial window. Providers should be prepared for complications of hemorrhage in renal failure patients requiring pericardiocentesis.

Dialysis Disequilibrium Syndrome

Dialysis disequilibrium syndrome is characterized by nausea, headache, malaise, vomiting, fatigue, and muscle cramps that occur during or immediately after hemodialysis. In severe cases, patients may exhibit altered mental status, seizures, or coma (although other probable causes of these altered mentation states should be excluded first before attributing such symptoms to dialysis disequilibrium syndrome).

The exact pathogenesis of the syndrome is unclear; it is believed to result from cerebral edema caused by shifts in osmolarity and pH during dialysis. Removal of small solutes such as urea from serum causes a rapid drop in serum osmolarity in the brain. This leads to the rapid ingress of free water, which results in cerebral edema.

The mainstay of treatment is prevention by avoiding rapid shifts in serum osmolarity during dialysis. Symptoms are usually self-limited and resolve within a few hours; severe cases can be treated by raising serum osmolarity with infusions of hyperosmolar solutions such as hypertonic saline or mannitol, in consultation with a nephrologist.^7,⁸

Dialysis Dementia

Dialysis dementia is a form of dialysis-related encephalopathy that is associated with dyspraxia and multifocal seizures. Unlike dialysis disequilibrium syndrome, dialysis dementia is slowly progressive in onset and generally occurs in patients who have been undergoing hemodialysis for at least 2 years. There are three forms of dialysis dementia:

1. An epidemic form believed to be due to contamination of dialysate with aluminum, which is usually excreted by the kidneys (the use of deionized water in dialysis has decreased the incidence of this form)

2. A sporadic endemic form whose cause remains unclear

3. A pediatric form that occurs in children with renal failure even when they have not yet undergone dialysis (this may be related to exposure to aluminum-containing medications)

Seizures in the ED should be treated with benzodiazepines; a serum aluminum level should be obtained in addition to performance of other standard laboratory tests if dialysis dementia is suspected (see Table 116.1).

Peritoneal Dialysis

Structure and Function

PD can be performed in a number of different ways; however, the complications associated with the various methods are similar. Typically, PD is performed with a Tenckhoff catheter (it can be straight or curved, single or dual cuffed) inserted in a median or paramedian line with or without omentectomy. Omentectomy is associated with fewer complications. The dialysate is infused into the abdomen via either a pump or gravity. It remains in the abdomen for a period, known as the dwell time, long enough to allow osmosis and diffusion. The effluent (or dialysate after dwelling in the abdomen) is then drained (Fig. 116.4).⁹

Fig. 116.4 Peritoneal dialysis catheters.

Complications

Complications of PD are organized into three groups: mechanical, infectious, and medical (Box 116.1).

Box 116.1

Complications of Peritoneal Dialysis (In Order of Frequency)

Mechanical

Catheter dislodgment

Catheter malfunction

Leakage, hernias, effusions

Infectious

Peritonitis

Cellulitis, tunnel infection

Abscess

Medical

Malnutrition, hypoalbuminemia

Bowel obstruction

Hyperglycemia

Data from U.S. Renal Data System, USRDS 2005 Annual Data Report. Atlas of end-stage renal disease in the United States. Bethesda, MD: National Institutes of Health, National Institute of Diabetes and Digestive and Kidney Diseases; 2005.

The most common and life-threatening complication is peritonitis, which causes the effluent to be turbid and cloudier than usual. This symptom should not be ignored. Patients are typically afebrile and otherwise well appearing. They do not have a rigid abdomen—instead, findings on physical examination are usually unimpressive, and the patient may at most complain of mild abdominal pain.

Peritonitis is usually the most common finding in patients with PD catheter malfunction, but other problems can arise.¹ Blood in the effluent suggests solid organ damage (especially if the catheter was placed recently), ruptured or leaking abdominal aortic aneurysm, or coagulopathy.

Mechanical Complications

Mechanical complications are related to the process of dialysis and include pump malfunction (for patients maintained on continuous cyclic or intermittent dialysis); inability to instill the dialysate or failure of the effluent to drain because of catheter malfunction or dislodgment; or leakage of fluid into the groin, across the diaphragm, or out of the abdominal wall.

Infectious Complications

Infectious complications include peritonitis, cellulitis at the catheter site, infection in the tunnel site itself, or intraabdominal abscesses.

Medical Complications

Most frequently, medical complications are related to nutrition. Hypoalbuminemia results from poor dietary intake and daily loss of 15 g of protein, which promotes infection by impairing normal immune function. Hyperglycemia occurs as a result of a large glucose load in the dialysate. Bowel obstruction can occur secondary to abdominal surgery.¹⁰

Differential Diagnosis

Although peritonitis is the most common cause of fever and abdominal pain or tenderness in a PD patient, patients with other intraabdominal infections may also have these symptoms. Swelling in the groin or shortness of breath suggests leakage of the dialysate because of the high intraabdominal pressure associated with instilling 2 L of fluid. Common abdominal infections in patients undergoing PD reflect those in the general population: appendicitis, cholecystitis, pancreatitis, and small bowel obstruction.

Diagnostic Testing

Mechanical Complications

Abdominal radiography is the most important modality. Radiographs confirm that the tube is placed correctly in the true pelvis, that no kinks are present, and that the tube has not broken into multiple pieces. Chest radiographs can reveal evidence of pleural effusion, and bowel obstruction is apparent on upright and lateral decubitus abdominal views. For suspected leaks, intraperitoneal water-soluble contrast material can be instilled to demonstrate communication with noted areas of swelling.

Infectious Complications

Culture is critical when testing for infectious complications. PD-associated peritonitis is defined as two of the following three: (1) signs and symptoms; (2) white blood cell (WBC) count higher than 100/mL in the PD effluent, with more than 50% neutrophils after a dwell time of at least 2 hours; and (3) positive culture of an organism from the PD effluent.¹¹ For patients undergoing automated PD who are being evaluated during their nighttime treatment, the dwell time will not be 2 hours, so the percentage of neutrophils should be used for diagnostic purposes even if the absolute WBC count is not higher than 100/mL. Bacteria in the peritoneal cavity have been diluted significantly by the dialysate, which can lead to negative cultures at standard volumes. To improve diagnostic results, 50 mL of effluent should be centrifuged down and the sediment resuspended in 3 to 5 mL of sterile saline before inoculation into both solid and liquid blood culture media. Alternatively, a minimum of 10 mL of effluent per blood culture bottle can be used. Blood cultures are not helpful unless the patient appears septic.¹²

Medical Complications

A comprehensive metabolic panel and serum lipase level should be obtained. Liver function tests and serum lipase levels can differentiate other causes of abdominal pain. Albumin levels are useful markers of malnutrition, which is present in 40% of these patients (25% of whom are severely malnourished). Hypoalbuminemia significantly increases the incidence of morbidity and mortality, especially in patients with peritonitis and those with a serum albumin concentration lower than 35 g/L. Hypokalemia causes decreased gut motility and constipation, which is associated with peritonitis; both conditions should be treated. Hyperglycemia, inadequate dialysis, and volume depletion or overload can be evaluated by physical examination and standard laboratory testing.¹⁰

Red Flags

Complications of Peritoneal Dialysis

Fever

Vomiting

Severe abdominal tenderness

Known or suspected fungal infection

Cloudy or turbid effluent

Treatment

Mechanical Complications

Most complications require removal of the peritoneal catheter or some type of surgical repair; patients need to be switched to hemodialysis until the catheter malfunction is resolved.

For a clogged catheter, attempts to empty the bladder and then the bowel (with laxatives) may improve function. If the catheter is clogged with fibrin or clot, heparin (500 U/L) can be added to the dialysate. If this fails, urokinase can be used as a last resort (5000 IU diluted in saline), which has a success rate of 10% to 15%.⁹

For catheter leakage, the amount of dialysate infused is decreased to lower intraabdominal pressure; the patient will probably still need surgical repair for correction.

In patients with catheter migration, kinking, dislodgment, and cuff extrusion, a one-time 2-g intravenous dose of ampicillin should be given for prophylaxis in the setting of tube manipulation.⁹

Infectious Complications

Gram-positive organisms account for three fourths of PD-associated infections, half of which are due to Staphylococcus epidermidis. Concerning organisms observed in infections are Pseudomonas, S. aureus (including MRSA), and fungal species.¹¹

If the patient has had culture-positive results in the past, these results can help guide antibiotic therapy. Otherwise, empiric antibiotic therapy should cover gram-positive and gram-negative organisms based on local hospital sensitivities.

Intermittent or continuous antibiotic therapy can be used with continuous ambulatory peritoneal dialysis (Table 116.2). Dosing regimens are different for patients undergoing automated PD. For intermittent treatment, antibiotics are added to only one of the four daily exchanges. For continuous therapy, a loading dose is given in the first exchange and then a maintenance dose is given in each exchange for the remainder of the course of treatment.¹²

Table 116.2 Intraperitoneal Antibiotic Dosing Recommendations for Patients Undergoing Continuous Ambulatory Peritoneal Dialysis *

ANTIBIOTIC	INTERMITTENT	CONTINUOUS^†
Aminoglycosides
Amikacin	2 mg/kg	LD 25, MD 12
Gentamicin, netilmicin, or tobramycin	0.6 mg/kg	LD 8, MD 4
Cephalosporins
Cefazolin, cephalothin, or cephradine	15 mg/kg	LD 500, MD 125
Cefepime	1000 mg	LD 500, MD 125
Ceftazidime	1000-1500 mg	LD 500, MD 125
Ceftizoxime	1000 mg	LD 250, MD 125
Penicillins
Amoxicillin	ND	LD 250-500, MD 50
Ampicillin, oxacillin, or nafcillin	ND	MD 125
Azlocillin	ND	LD 500, MD 250
Penicillin G	ND	LD 50,000 units, MD 25,000 units
Quinolones
Ciprofloxacin	ND	LD 50, MD 25
Others
Aztreonam	ND	LD 1000, MD 250
Daptomycin	ND	LD 100, MD 20
Linezolid	200-300 mg/day orally
Teicoplanin	15 mg/kg	LD 400, MD 20
Vancomycin	15-30 mg/kg every 5-7 days	LD 1000, MD 25
Antifungals
Amphotericin	NA	1.5 mg/L
Fluconazole	200 mg IP every 24-48 hr
Combinations
Ampicillin-sulbactam	2 g every 12 hr	LD 1000, MD 100
Imipenem-cilastin	1 g bid	LD 250, MD 50
Quinupristin-dalfopristin	25 mg/L in alternate bags^‡
Trimethoprim-sulfamethoxazole	960 mg orally bid

bid, Two times per day; IP, intraperitoneally; LD, loading dose; MD, maintenance dose; NA, not applicable; ND, no data.

^* For dosing of drugs with renal clearance in patients with residual renal function (defined as >100 mL/day of urine output), the dose should be empirically increased by 25%.

^† Per exchange, once daily (mg/L; all exchanges).

^‡ Given in conjunction with 500 mg intravenously twice daily.

Doses for renally excreted drugs should be increased by 25% if the patient produces more than 100 mL of urine per day.¹²

Fungal infections may occur after antibiotic treatment. They require early removal of the catheter and are associated with a mortality of 25%.¹²

Exit site infections should be treated with oral antibiotics except in some cases of MRSA.¹¹ Therapy is guided by Gram stain of the purulent drainage and by previous treatment regimens, although S. aureus, S. epidermidis, and Pseudomonas aeruginosa are responsible for the majority of infections. For first-time infections, immediate empiric antibiotic treatment of gram-positive organisms should be initiated (cephalexin, 500 mg orally two to three times daily). Suspected MRSA infections should be treated with vancomycin, clindamycin, Bactrim, or rifampin (do not use rifampin as monotherapy). Patients with MRSA infections may also be given intranasal and local mupirocin (cream, not ointment, because the polyethylene glycol in the ointment can damage the polyurethane in some PD catheters) twice a day for 5 to 7 days. Suspected pseudomonal infections should be treated with quinolones, although double therapy in accordance with local susceptibility patterns is recommended because of the rapid rise of resistance.¹¹ The duration of treatment is at least 2 weeks for gram-positive organisms and 3 weeks for pseudomonal organisms.

Medical Complications

Management of most medical complications in PD patients is similar to that in the general population. Hyperglycemia can be treated with intraperitoneal insulin, but at higher doses.¹¹ Hypokalemia should be treated aggressively because it leads to constipation and risk for peritonitis. Hypoalbuminemia should be managed with protein supplements and education of the patient. In severe cases, total parenteral nutrition or intravenous albumin (or both) may be necessary.¹⁰