CCRN (Adult) key terms

The volume of oxygen transported to the tissues each minute, calculated as cardiac output multiplied by arterial oxygen content. When it falls below tissue demand, anaerobic metabolism and lactic acidosis develop.

The volume of blood the heart ejects each minute, equal to heart rate multiplied by stroke volume. Typical resting adult values are roughly 4 to 8 liters per minute.

The volume of blood ejected from a ventricle with each contraction, determined by preload, afterload, and contractility. A typical adult resting value is about 60 to 100 mL per beat.

The degree of ventricular stretch at end-diastole, reflecting how much blood fills the chamber. It is estimated clinically using pressures such as central venous pressure or pulmonary artery occlusion pressure.

The resistance the ventricle must overcome to eject blood during systole. It rises with vasoconstriction, aortic stenosis, and elevated systemic vascular resistance, and it falls with vasodilator drugs.

The intrinsic strength of myocardial fibers independent of preload and afterload. It increases with sympathetic stimulation and inotropic drugs, and it decreases in ischemia and heart failure.

The average arterial pressure across one cardiac cycle, approximated as one-third systolic plus two-thirds diastolic pressure. It reflects perfusion pressure for vital organs; adults generally need at least 65 mmHg.

The resistance to blood flow offered by the systemic vasculature, derived from mean arterial pressure, central venous pressure, and cardiac output. It rises with vasoconstriction and falls with vasodilation or vasodilator therapy.

The oxygen saturation of blood sampled from the pulmonary artery, usually through a pulmonary artery catheter. It reflects the balance between oxygen delivery and consumption; normal is about 65 to 75 percent.

A pressure obtained by inflating the balloon of a pulmonary artery catheter, used as an estimate of left atrial pressure and left ventricular filling. Values are interpreted alongside cardiac output and clinical findings.

The portion of each breath that reaches conducting airways or unperfused alveoli without participating in gas exchange. It increases with pulmonary embolism, low cardiac output, and excessive ventilator pressures, raising PaCO2.

Blood that passes through the lungs without contacting ventilated alveoli, so it returns to the left heart poorly oxygenated. Shunt responds little to supplemental oxygen because the blood never reaches functioning alveoli.

The airway pressure measured during an inspiratory hold, reflecting alveolar pressure and lung stretch. Keeping it at or below 30 cm H2O helps prevent ventilator-induced lung injury.

Trapped gas and residual positive pressure remaining in the alveoli at end-expiration, usually because exhalation is incomplete. It can impair venous return, cause hypotension, and increase work of breathing.

The volume of air moved into or out of the lungs with each breath. Lung-protective ventilation in acute respiratory distress syndrome typically uses about 6 mL/kg of predicted body weight.

The ratio of arterial oxygen partial pressure to the fraction of inspired oxygen, used to grade hypoxemia severity. A ratio below 300 suggests acute lung injury, and below 100 suggests severe impairment.

The difference between measured serum cations and anions, used to sort out causes of metabolic acidosis. A widened gap suggests accumulation of unmeasured acids such as lactate or ketones.

A calculated value describing the metabolic component of acid-base status, representing the strong acid or base needed to restore normal pH under standard conditions. Negative values indicate metabolic acidosis.

The pressure gradient driving blood flow to the brain, calculated as mean arterial pressure minus intracranial pressure. Targets are typically 60 to 70 mmHg in adults with acute brain injury.

The pressure exerted inside the rigid skull by brain tissue, blood, and cerebrospinal fluid. Sustained elevations above roughly 20 mmHg threaten cerebral perfusion and require prompt intervention.

Life-threatening organ dysfunction caused by a dysregulated host response to infection. It is identified by a rise in organ failure assessment scores and requires early antibiotics, cultures, and fluid resuscitation.

Sepsis with persistent hypotension requiring vasopressors to maintain mean arterial pressure and a lactate level above 2 mmol/L despite adequate fluid resuscitation. Mortality is high without early recognition and treatment.

An abrupt decline in kidney function marked by rising serum creatinine or falling urine output. Causes are grouped as prerenal, intrinsic renal, and postrenal, and management focuses on fluids and hemodynamic optimization.

A slow, continuous extracorporeal therapy that removes fluid and solutes in hemodynamically unstable patients with kidney failure. It is typically delivered through a dialysis catheter in the intensive care unit.

Continuous measurement and display of carbon dioxide in exhaled breath. It confirms endotracheal tube placement, monitors ventilation, and can suggest low cardiac output or bronchospasm.

The likelihood that a patient's cardiac output will rise after a fluid bolus. Dynamic measures such as pulse pressure variation or a passive leg raise predict it better than static filling pressures do.

Progressive dysfunction of two or more organ systems after an acute insult such as sepsis, trauma, or shock. It reflects widespread inflammation and ischemia and is a leading cause of intensive care unit death.

The ethical duty to act in ways that promote the patient's health and well-being. It underlies interventions intended to help and requires balancing likely benefits against burdens and risks.

The ethical duty to avoid causing harm, often summarized as above all do no harm. It requires weighing the risks of tests and treatments and avoiding interventions whose burdens outweigh their likely benefits.

The principle that patients with decision-making capacity may determine their own care. Respecting it means giving information, honoring informed refusals, and avoiding paternalism even when clinicians disagree with the choice.

The ethical obligation to tell the truth and avoid deceiving patients or families. It supports informed consent and trust, and it is balanced against sensitivity when sharing difficult information.

A process in which a person with capacity voluntarily agrees to treatment after understanding its purpose, risks, benefits, and alternatives. It requires adequate disclosure, comprehension, and freedom from coercion.

A legal document prepared while a person has capacity that states preferences for future medical care or names someone to decide. Examples include living wills and durable powers of attorney for health care.

A legal designation naming a surrogate to make medical decisions if the patient loses capacity. The surrogate should follow the patient's known wishes and, when these are unknown, the patient's best interests.

A clinical judgment that a proposed intervention cannot achieve its intended goal, such as restoring meaningful survival. Disagreements about futility often require ethics consultation and clear, ongoing communication with families.

The experience of knowing the ethically appropriate action but feeling prevented from taking it by institutional, clinical, or hierarchical constraints. It contributes to nurse burnout and to compromised patient care.

Acting to protect and promote a patient's rights, values, and preferences, especially when the patient cannot speak for themselves. Nurse advocates question unsafe orders and confirm patients understand their options.

Transferring responsibility for performing a specific task to another team member while retaining accountability for the outcome. It requires assessing the task, the delegate's competence, and the level of supervision needed.

An organizational approach that encourages reporting errors and near misses without blame for human error, while still holding people accountable for reckless behavior. It supports safety, transparency, and organizational learning.