22 Renal failure and dialysis
Jocelyn M. De Guzman and Bryan B. Kitch
Introduction
Renal failure in its various forms represents a spectrum of disease with profound implications for patient management. With differing etiologies for both acute and chronic forms of the disease, patients may present with a wide variety of complaints that directly relate to their renal function. This chapter will discuss the array of disorders, including acute, chronic, and end‐stage renal disease; their complications; and treatments most pertinent to EMS clinicians.
A brief review
According to the 2019 United States Renal Data System annual report, close to 750,000 people in the United States are living with end‐stage kidney disease (ESRD). Of those receiving treatment, 63% were undergoing hemodialysis, 7% peritoneal dialysis, and 30% had functional transplanted kidneys. While the number of prevalent cases continues to rise, the incidence of new cases has plateaued, owing to an increased number of patients starting renal replacement therapy, increased survival rates, and longer life expectancy of this population [1]. With the increasing number of ESRD patients potentially using the EMS system, the EMS physician must ensure that education about renal emergencies is an integral part of training and protocols.
Receiving approximately 20% of the body’s cardiac output, the kidneys function to filter blood through their 2 million nephrons. The series of microscopic and macroscopic elements serve to filter waste, complex metabolites, and excess fluids, exchange electrolytes, and manage acid and base regulation with the resultant fluid being excreted from the nephron. Additionally, the kidney controls red blood cell production with the production of erythropoietin and has a role in blood pressure regulation through renin secretion. Renal function is largely defined by estimated glomerular filtration rate in milliliter/minute/1.73 m2 (body surface area), with lesser values corresponding to more severe renal impairment [2].
Renal failure encompasses the entire spectrum of kidney malfunction including acute kidney injury, chronic kidney disease (CKD), and ultimately ESRD. Progression between acute and chronic disease is patient‐specific, dependent on several factors, including etiology of renal insult, reversibility of damage, and timeliness of treatment. While the specific pathophysiology differentiating each stage of disease will not be covered in this chapter, it is imperative for the EMS clinician to be able to identify and manage the emergent clinical presentations associated with renal failure.
Renal replacement therapy
Renal replacement therapy includes the modalities of hemodialysis, peritoneal dialysis, continuous renal replacement therapy, and renal transplant. While typically employed for treatment of ESRD, these therapies are also used for management of severe cases of acute kidney injury including poisonings, symptomatic uremia, and severe fluid overload.
Hemodialysis
Hemodialysis filters the patient’s blood to rapidly remove fluid and solutes. Home hemodialysis is possible for select patients. Specialized vascular devices enable rapid infusion and removal of blood. These devices must be able to support over 350 mL/min of blood flow, with some patients achieving rates of 600‐1200 mL/min [3].
A dialysis patient’s access site should not be used except in critical emergencies (e.g., cardiac arrest resuscitation). Patients are advised to avoid use of blood pressure cuffs, tourniquets, and venipuncture on the extremity that has their access, and they will typically convey this concern to EMS personnel [4]. There are several dialysis access options:
AV fistula – a surgically created connection between an artery and a vein, usually from the brachial or radial artery to the cephalic vein. It takes longer than 4 weeks, and often more than 8 weeks, to “mature” and be ready to use. A patient may have a fistula created and be in the process of maturation while using a different access device for dialysis [5].
AV graft – similar to a fistula, the artery and the vein are connected by way of a synthetic device. It is more prone to complications than a fistula [5].
Tunneled catheter – a large IV catheter that accesses a central vein, usually the internal jugular [6]. Prior to entering the vein, the catheter is run through the skin and soft tissue from a different site (i.e., tunneled). Doing so reduces risks of infection and need for frequent dressing changes [7]. The catheters are often held in place by balloons and other securing devices. This method has the advantage in that it is immediately available for use once inserted. Compared to other long‐term methods of venous access, the catheter has the highest rates of complication and mortality [4,7].
Nontunneled catheter – a large‐bore IV in a central vein with two ports. It is typically used as a temporary bridge to a different device [8].
Peritoneal dialysis
For peritoneal dialysis, the patient’s own abdominal contents, rather than an external machine, serve as the dialysis membrane. The patient has a permanent catheter through the abdominal wall, which itself can be a source of complications. Typically, the patient will require several exchanges of fluid to reach his or her goal. The exchanges may be automated to occur during sleep or may be performed with several extraction/replacements of fluid spaced throughout the day [4, 9].
Renal transplant
An alternative to dialysis for ESRD patients is renal transplantation. A successful transplant can allow a dialysis‐dependent patient to live a nearly normal.
Typically, the patient’s new kidney is implanted in the abdominal cavity or pelvis. This has implications for any patient complaining of abdominal pain. A renal cause (e.g., transplant rejection) must be considered. Furthermore, the kidney is not protected in its native location in the retroperitoneum. The physical exam and focused history after trauma should be mindful of this anatomical difference, although outcomes and injury patterns may not be significantly different from those of nontransplant patients [10].
Kidney transplant patients continue to receive immunosuppressive medication to avoid rejection. They may not mount fevers with infection and are at risk for atypical and opportunistic infections. Vague and mild symptoms may actually be concerning signs and should warrant careful evaluation. A thorough medication history can alert the EMS clinician to the presence of immunosuppression.
Complications of renal disease
Many of the complications of renal failure are more likely to be found in those with no remaining renal function. While possible in the acute renal failure patient, those known to be dialysis dependent more often present to EMS with one or more of the following acute complications of chronic disease.
Fluid overload
Fluid overload in renal disease is similar to congestive heart failure. Given the prevalence of comorbidities such as hypertension and cardiac disease in this population, dyspnea and pulmonary edema may result from either pump failure from a primary cardiac etiology, or excretion failure from the poor renal function. Additionally, the ESRD patient may enter a state of high‐output heart failure due to the presence of an AV fistula. The inability to clear waste products can also result in uremic cardiomyopathy [4].
Diagnosis and treatment of fluid overload in this patient population overlap
