Advanced practice nurses (APNs) are registered nurses prepared at the master’s or doctoral level. They function in a multitude of inpatient and outpatient settings across the health care continuum. APN roles include Clinical Nurse Specialist (CNS), Nurse Practitioner (NP), Certified Nurse–Anesthetist, and Nurse Midwife. Though their practice environments, patient populations, specialty knowledge-base and skill sets vary greatly, all APNs share core competencies of direct clinical practice, expert coaching and guidance, consultation, research, clinical and professional leadership, collaboration, and ethical decision-making [1]. CNSs and Acute Care Nurse Practitioners (ACNPs) possess education and expertise in areas that uniquely equip them to practice in the critical care environment. All APN roles require advanced nursing knowledge and skills; the roles are not the same as those held by physicians, although APN practice may be similar to physicians in many medical therapeutic realms [1]. When APNs begin to transfer new skills or interventions into their practice, they become nursing skills, informed by the clinical practice values of the nursing model: “the advanced practice of nursing is not the junior practice of medicine [1].”

This chapter describes the Acute Care CNS and ACNP roles, scope of practice, certification, credentialing, and reporting mechanisms. In addition, the science related to outcomes of APN practice and co-practice with other providers is discussed.

CNS—A CNS is an expert clinician in a specialized area of nursing practice. The specialty may be defined by a population (women), a setting (critical care unit), a disease or medical subspecialty (cardiovascular disease), a type of care (rehabilitation), or a type of problem (wounds) [1,2]. The CNS approaches the APN role through three spheres of influence: at the patient level in direct care, at the nurse level with staff development, and at the institution level providing oversight of care [1]. Staff education and system change responsibilities represent a large percentage of the CNS’s role [1]. In each of the spheres of influence, the primary goal of the CNS is continuous improvement of patient outcomes and nursing care. Key elements of CNS practice are to create environments through mentoring and system changes that empower nurses to develop caring, evidence-based practices. The CNS is responsible and accountable for diagnosis and treatment of health-illness states, disease management, health promotion, and prevention of illness and risk behaviors among individuals, families, groups, and communities [3].

ACNP—Of the APN categories, nurse practitioners (NPs) have undergone the broadest expansion in practice arenas. Emerging from the primary care setting, NPs began to expand their role into specialty and subspecialty areas in response to population changes in health care. Preparing NPs for acute care practice began in the early 1990s as a response to the need for advanced level practitioners in the inpatient, acute and critical care settings. Only ACNPs have been educated and trained to manage critically ill patients in ICU settings, but NPs with other educational preparation (such as family, adult, or gerontology) may practice in other hospital areas. However, this use of other NPs in the acute care setting has been questioned, as their scope of practice (academic preparation and experience) does not always include acute care patient management [4].

Though both CNS and ACNP are targeted to a patient-centered approach to care for patient populations, the continuous on-unit presence of the ACNP at the bedside of patients often differentiates the role of the ACNP from the CNS role [1]. In a 2006 American Association of Critical Care Nurses (AACN) study of APN practice, ACNPs reported spending 74% of their practice time directed toward individual patient management, while CNSs divided their time between nursing personnel (36%), populations of patients (21%), and other disciplines, organizations, or systems (17%) [4]. The primary responsibilities of ACNPs involve activities related to direct management of patient care, accounting for 85% to 88% of time spent in the role [5]. Key elements of the ACNP role include conducting physical examinations and comprehensive health assessments, gathering patients’ medical histories, ordering and interpreting the full spectrum of diagnostic tests and procedures, use of differential diagnoses to reach a medical diagnosis, prescribing medications, providing and evaluating the outcomes of interventions, conducting rounds, initiating transfers and consultations, and preparing patients for discharge [6,7]. ACNP care includes health promotion, disease prevention, health education, and counseling as well as the diagnosis and management of acute and chronic diseases [3].

Credentialing is furnishing the documentation necessary to be authorized by a regulatory body or institution to engage in
certain activities and to use a certain title [1]. In all states, APN regulation for practice is based on basic nursing licensure, but many states have additional rules and regulations that delineate requirements and define and limit who can use a specific advanced practice nursing title [1,7]. Nurse practice acts are administered under the authority of state governments to assure public safety [7]. In 23 states, the board of nursing has sole authority over advanced practice nursing; in others, there is joint authority with the board of medicine, the board of pharmacy, or both [8]. Advanced practice nursing certification is national in scope, and it is a mandatory requirement for APNs to obtain and maintain credentialing in most states [9]. APNs must fulfill continuing education (CE) and practice requirements to successfully maintain their national certification, although requirements differ from specialty to specialty. Each advanced practice nursing certification entity clearly lays out the requirements and time frame for recertification. National certifications for most specialties last from 5 to 8 years, and require that the candidate retest unless established parameters are met [1].

Credentialing and licensure for prescriptive authority also occur at the state level. Pharmacology requirements vary from state to state, with most states requiring a core advanced pharmacotherapeutics course during the graduate APN educational program, and yearly continuing education credits to maintain prescriptive privileges [1].

The requirement for APN hospital privileges varies according to the nurse’s practice. Many hospitals have different levels of hospital privileges, ranging from “full” privileges to modified privileges for specific functions [1]. A collaborative practice agreement exists between an APN and physician to define parameters of practice for the APN. Many states require this as part of APN licensure [8]. This agreement may take many forms, from a one-page written agreement defining consultation and referral patterns to a more specific prescribed protocol for specific functions based on state statues for APNs. These agreements should be written as broadly as possible to allow for practice variations and new innovations [1].

CNS—Upon completion of an accredited graduate CNS program, certification by examination is available through the American Nurses Credentialing Center (ANCC), or through the certification boards of specialty organizations. The American Association of Critical Care Nurses (AACN) offers a Critical Care Nurse Specialist exam [2]. However, certification exams are not available for many CNS specialties. This is a major regulatory barrier for many CNS specialties in those states that require CNS certification for second licensure [1]. Creating a universal CNS certification examination is in the forefront of current efforts to address this problem. Some states allow prescriptive authority for CNSs.