NRSG 1200: Pathophysiology - Perfusion and Gas Exchange

Vocabulary practice flashcards covering cardiovascular perfusion, hemodynamics, regulatory systems, blood pressure, shock stages, gas exchange physiology, and pulmonary pathophysiology from NRSG 1200.

Perfusion

The flow of blood through systemic tissues that delivers essential oxygen and nutrients to cells.

Spectrum of Perfusion

A physiological continuum spanning from optimal tissue perfusion, to impaired perfusion, down to an absence of perfusion resulting in tissue death.

Right Heart Circuit

The circulatory route where deoxygenated systemic venous blood empties into the right atrium and right ventricle, which then pumps it through the pulmonary arteries to the lungs.

Left Heart Circuit

The circulatory route where oxygenated blood returns from the pulmonary veins into the left atrium and left ventricle, which then ejects it into the aorta to supply systemic tissues.

Cardiac Output

The volume of blood pumped by the heart each minute, defined by the relationship: $\text{Cardiac output} = \text{heart rate} \times \text{stroke volume}$.

Stroke Volume

The volume of blood ejected by the ventricle with each individual heartbeat.

Preload

The degree of stretch on ventricular muscle fibers at the end of diastole, largely determined by end-systolic volume and venous return.

Afterload

The resistance or pressure that the ventricles must overcome to eject blood, primarily influenced by aortic pressure and total peripheral resistance.

Contractility

The intrinsic force or strength of ventricular myocardial contraction, influenced by sympathetic stimulation, end-diastolic volume, and myocardial oxygen supply.

Baroreceptors

Sensory pressure receptors that provide rapid reflex responses to regulate arterial blood pressure.

Renin-Angiotensin-Aldosterone System (RAAS)

A hormonal regulatory mechanism activated to maintain blood pressure by promoting vasoconstriction and renal retention of fluid and sodium.

Natriuretic Peptides

Endocrine peptides that promote urinary sodium and water excretion to reduce circulating blood volume and blood pressure.

Vascular Resistance and Lumen Diameter

The relationship wherein narrowing of a vessel lumen increases resistance and reduces blood flow at an equivalent pressure gradient.

Sustained Hypertension

A chronic elevation in systemic pressure where blood pressure regulation remains altered due to factors such as increased vascular tone, arterial stiffness, altered renal sodium handling, and heightened sympathetic activity.

Target Organs of Hypertension

The major body organs vulnerable to chronic high-pressure injury: the brain (cerebrovascular risk), retina (small-vessel injury), heart (increased ventricular workload), and kidneys (vascular and filtration impairment).

Blood Pressure Measurement Technique

The clinical procedure requiring appropriate cuff sizing (covering correct arm length and circumference), arm support, adequate patient rest, and repeat readings to establish a reliable baseline.

Endothelial Dysfunction

Impaired function of the inner vessel lining that reduces normal vascular protection and promotes lipid accumulation and inflammation within the artery wall.

Atherosclerosis

A pathological vascular process where lipids, inflammatory components, and plaque accumulate inside arterial walls, gradually narrowing the lumen and restricting regional flow.

Arterial Thrombus

A blood clot triggered by atherosclerotic plaque disruption that can suddenly occlude vessel lumen diameter and acutely compromise perfusion.

Ankle-Brachial Index (ABI)

A noninvasive cardiovascular diagnostic comparison of systolic blood pressure between the ankle and brachial arteries to evaluate arterial perfusion to the lower extremities.

Ventilation

The mechanical movement of air through the conducting airways into and out of the alveoli.

Diffusion

The passive transfer of gases across the alveolar-capillary membrane driven by partial-pressure gradients and facilitated by increased surface area and membrane thinness.

Pulmonary Perfusion

The delivery of capillary blood flow to the alveoli to participate in pulmonary gas exchange.

Matched V/Q Pattern

A normal pulmonary state where adequate alveolar air ventilation is appropriately paired with adequate pulmonary capillary blood flow, effectively supporting gas exchange.

Low V/Q Ratio

A ventilation-perfusion mismatch characterized by reduced air reaching the alveoli despite continued capillary blood flow, resulting in less effective blood oxygenation.

High V/Q Ratio

A ventilation-perfusion mismatch characterized by ongoing alveolar air delivery paired with reduced capillary blood flow, resulting in wasted ventilation (dead space).

SpO2 (Pulse Oximetry)

An estimate of arterial hemoglobin oxygen saturation that does not reflect total hemoglobin content, blood flow, or $\text{CO}_2$ elimination.

PaO2

The partial pressure of oxygen physically dissolved in arterial blood ($\text{exercise normal range: } 80\text{--}100\text{ mm Hg}$), reflecting arterial oxygenation rather than total oxygen content.

PaCO2

The partial pressure of carbon dioxide dissolved in arterial blood ($\text{exercise normal range: } 35\text{--}45\text{ mm Hg}$), indicating the respiratory component of ventilation.

Bicarbonate (HCO3-)

The primary form through which carbon dioxide is transported in circulating blood ($\text{exercise normal range: } 22\text{--}26\text{ mEq/L}$), representing the metabolic contribution to acid-base balance.

Arterial Blood pH

The clinical measure of systemic acidity or alkalinity, with a normal exercise reference interval of $7.35\text{--}7.45$.

Pneumonia

A gas exchange disorder marked by inflammatory material and exudate filling the alveolar air space, reducing aeration while capillary blood flow may continue through affected zones.

Asthma

A respiratory condition characterized by airway inflammation, smooth muscle constriction, and mucus production that together narrow the lumen and raise airflow resistance.

Chronic Obstructive Pulmonary Disease (COPD)

A pulmonary disorder involving airway disease and/or emphysema marked by persistent expiratory airflow limitation, loss of elastic recoil, and air trapping.

Emphysema

A structural component of COPD defined by the enlargement and destruction of alveolar walls, leading to reduced recoil and air trapping.

Consolidation

An imaging finding indicating that fluid, cells, or inflammatory exudate have filled the normally aerated alveolar spaces.

Spirometry

A pulmonary function test that measures expiratory airflow rates and volumes to evaluate airflow limitation.

Acute Respiratory Distress Syndrome (ARDS)

A severe form of acute lung injury wherein alveolar-capillary barrier disruption leads to non-cardiogenic fluid leakage, surfactant dysfunction, alveolar collapse/flooding, and markedly decreased compliance.

Respiratory Failure

A life-threatening clinical state where the respiratory system fails to maintain adequate arterial oxygenation, carbon dioxide elimination, or both.

Controlled Oxygen Therapy in COPD

The clinical titration of supplemental oxygen to a specific target (commonly $\text{SpO}_2\text{ of } 88\text{--}92\%$) during exacerbations, without withholding emergent therapy.

Heart Failure

A general term describing several types of cardiac dysfunction that result in inadequate tissue perfusion with blood-borne nutrients.

Left-Sided Heart Failure

Ventricular failure commonly caused by hypertension, coronary artery disease, or valvular disease, presenting with exertional dyspnea, paroxysmal nocturnal dyspnea, fatigue, weakness, arm heaviness, and palpitations.

Right-Sided Heart Failure

Ventricular failure caused by left ventricular failure, right ventricular myocardial infarction, or pulmonary hypertension, manifesting with jugular vein distention, dependent edema, hepatomegaly, ascites, and increased abdominal girth.

Daily Weight Measurement

The single most reliable clinical indicator of acute fluid retention or fluid loss in patients with heart failure.

B-Type Natriuretic Peptide (BNP)

A primary laboratory diagnostic test used to detect cardiac wall stretch and assist in diagnosing and evaluating heart failure.

Shock

Widespread abnormal cellular metabolism occurring when gas exchange, oxygenation, and tissue perfusion needs are not sufficiently met to sustain normal cellular function across all organ systems.

Four Classifications of Shock

The clinical categories of shock based on underlying etiology: hypovolemic, cardiogenic, distributive (neurogenic, septic, anaphylactic), and obstructive.

Initial Stage of Shock

The stage of shock characterized by a baseline mean arterial pressure (MAP) reduction of $<10\text{ mm Hg}$, subtle vascular constriction, and increased heart rate, with clinical manifestations being difficult to detect.

Compensatory Stage of Shock

The shock stage where MAP decreases by $10\text{--}15\text{ mm Hg}$, kidney and hormonal mechanisms activate, urine output decreases, tissue hypoxia develops, and the patient reports subjective thirst and anxiety.

Progressive Stage of Shock

A life-threatening medical emergency defined by a sustained decrease in MAP of $>20\text{ mm Hg}$ from baseline, vital organ hypoxia, rapid weak pulse, pallor, cool moist skin, anuria, and falling $\text{SpO}_2$; requiring correction within $1\text{ hour}$ or less.

Refractory Stage of Shock

The irreversible final stage of shock marked by widespread cellular death, nonpalpable pulses, cold dusky extremities, slow shallow respirations, unmeasurable oxygen saturation, and Multiple Organ Dysfunction Syndrome (MODS).

Multiple Organ Dysfunction Syndrome (MODS)

A progressive sequence of extensive cellular and tissue damage resulting from a massive systemic release of toxic metabolites and destructive enzymes during irreversible shock.

Serum Lactate

A critical diagnostic laboratory test in shock evaluation that quantifies anaerobic metabolism and the severity of cellular hypoperfusion.