AD 165 Module 7: Gas Exchange and Thorax & Lungs Study Guide

Comprehensive practice flashcards for AD 165 Module 7 covering thoracic structures and functions, mechanics of gas exchange, systematic lung assessment, lifespan considerations, abnormal respiratory patterns and sounds, acute and chronic pulmonary conditions, and respiratory health promotion.

What is the overarching question that should be asked about every pulmonary condition in this unit?

Is the air not getting in (a ventilation problem) or is the blood not getting there (a perfusion problem)?

Where does the second rib attach anteriorly, marking the starting landmark to begin counting ribs and intercostal spaces?

At the sternal angle (angle of Louis).

What is the normal measurement of the costal angle, and under what conditions does it widen?

The costal angle is normally $\le 90^\circ$; it widens in pregnancy and in patients with a barrel chest.

Which vertebra corresponds to the prominent bony bump at the base of the neck, and where do the inferior angles of the scapulae lie?

The bump at the base of the neck is $C7$ (vertebra prominens); the inferior angles of the scapulae sit at approximately the $7\text{th}\text{--}8\text{th}$ ribs.

What anatomical structures comprise the acinus?

The respiratory bronchiole, alveolar ducts, alveolar sacs, and alveoli.

What are the three vertical imaginary reference lines located on the lateral chest wall?

The anterior axillary line (front fold of the armpit), midaxillary line (middle apex of the axilla), and posterior axillary line (back fold of the armpit).

How do the right and left lungs differ in lobe number and anatomy, and why?

The right lung has $3$ lobes (RUL, RML, RLL) and is shorter to accommodate the liver; the left lung has $2$ lobes (LUL, LLL) and is narrower to accommodate the heart.

What are the two layers of the pleura, and what abnormal sound occurs when loss of lubrication causes them to grind together?

The visceral pleura (inner layer wrapping the lung surface) and parietal pleura (outer layer lining the chest wall and diaphragm); their grinding creates a pleural friction rub.

From which anatomical views can the right middle lobe (RML) be auscultated?

The right middle lobe (RML) can only be heard from the anterior and lateral views on the right side; it is not accessible posteriorly.

Which brainstem centers control involuntary breathing, and what is the primary stimulus to breathe?

Breathing is controlled by the medulla and the pons; the primary stimulus is a rise in $CO_2$ in the blood (hypercapnia), while a drop in blood $O_2$ (hypoxemia) also acts as a trigger.

What muscular actions and pressure gradients occur during active inspiration versus passive expiration?

During inspiration (active), the diaphragm contracts and descends while external intercostals elevate the ribs, causing thoracic volume to increase and intrathoracic pressure to decrease so air flows in. During expiration (passive), the diaphragm relaxes and rises as the lungs recoil, decreasing volume and increasing pressure to force air out.

What does accessory muscle use at rest indicate during a respiratory assessment?

It is a red flag indicating the patient is working hard to breathe, experiencing respiratory distress, and requires immediate intervention.

How is ventilation distinguished from perfusion in gas exchange?

Ventilation is the mechanical process of moving air into and out of the alveoli, whereas perfusion is blood flowing through the pulmonary capillaries to pick up oxygen and release carbon dioxide.

What is the difference between hypoxemia and hypoxia?

Hypoxemia is reduced oxygenation in the arterial blood (measured via $SpO_2$ or arterial blood gas), whereas hypoxia is insufficient oxygenation within the cells and tissues.

How are ischemia, anoxia, and hypercapnia defined?

Ischemia is insufficient blood flow of oxygenated blood to tissue (usually from a clot or vasoconstriction); anoxia is a total lack of oxygen delivery to tissues; hypercapnia is an elevation of carbon dioxide ($CO_2$) in the blood.

How is a patient's smoking history calculated in pack-years?

Pack-years equal the number of cigarette packs smoked per day multiplied by the total years smoked (for example, $1\text{ pack/day} \times 20\text{ years} = 20\text{ pack-years}$).

What is the correct four-step sequence for an objective physical lung examination?

Inspection, followed by palpation, percussion, and auscultation.

What is the normal expected finding for a capillary refill assessment?

Color returns to the blanched nail bed within approximately $2\text{--}3\text{ seconds}$; prolonged refill indicates compromised peripheral perfusion or oxygenation.

What is a flail chest, and why is it considered a medical emergency?

Flail chest occurs when multiple rib fractures allow a segment of the chest wall to move paradoxically on its own (sucking inward during inspiration when the rest expands outward), causing asymmetric chest wall motion and severe ventilatory compromise.

How is posterior symmetric chest expansion assessed during palpation, and what does asymmetric lag signify?

Place hands posterolaterally with thumbs pointing toward the spine at approximately $T9\text{--}T10$, pinch a small skin fold, and instruct the patient to take a deep breath; thumbs should move apart symmetrically. A unilateral lag indicates conditions such as atelectasis, pneumonia, pleural effusion, or thoracic trauma.

What do increased and decreased tactile fremitus indicate upon palpation?

Tactile fremitus increases with consolidation (e.g., pneumonia) because solid tissue conducts sound vibrations effectively; it decreases with pleural effusion, pneumothorax, or emphysema because fluid, free air, or hyperinflation obstructs vibration transmission.

What is crepitus, and what underlying condition causes it?

Crepitus is a coarse crackling sensation palpated under the skin ("like Rice Krispies") caused by subcutaneous emphysema when air escapes the lungs into the subcutaneous tissue.

What clinical states correspond to resonant, dull, and hyperresonant thoracic percussion notes?

Resonance is the normal finding over healthy lung tissue; dullness indicates fluid or solid consolidation (such as pneumonia or atelectasis); hyperresonance indicates abnormal trapped air (such as emphysema or pneumothorax).

Where are vesicular, bronchovesicular, and bronchial breath sounds normally heard, and what are their relative inspiratory-to-expiratory (I:E) ratios?

Vesicular sounds are soft and low-pitched, heard over peripheral fields with inspiration longer than expiration ($3:1$); bronchovesicular sounds are moderate in pitch, heard beside the sternum ($1\text{st}\text{--}2\text{nd}$ intercostal spaces) and between the scapulae with equal phases ($1:1$); bronchial (tracheal) sounds are loud and high-pitched, heard over the trachea and larynx with expiration longer than inspiration ($1:2$).

What abnormal pathology is indicated when bronchial breath sounds are auscultated over the peripheral lung fields?

Consolidation (such as lobar pneumonia), because dense consolidated tissue conducts harsh central airway sounds directly out to the periphery.

What do the abnormal voice sound tests bronchophony, egophony, and whispered pectoriloquy signify?

All three indicate lung consolidation (e.g., pneumonia); bronchophony makes spoken '99' sound loud and clear, egophony causes spoken 'ee' to sound like 'aa', and whispered pectoriloquy makes whispered words distinct and clear.

What stethoscope technique and sequencing rules should be followed during thoracic auscultation?

Place the stethoscope diaphragm directly on bare skin, listen for one full respiratory cycle at each spot, evaluate at least $6$ locations per side comparing side to side at each level (ladder pattern), and place the posterior apices slightly higher for optimal sounds.

What are normal expected respiratory findings in an infant regarding breathing route, rate, and chest dimensions?

Infants are obligate nose breathers until $3\text{ months}$, abdominal/belly breathers, have a normal newborn rate of $30\text{--}40\text{ breaths/min}$ (up to $60$), exhibit brief normal apnea under $10\text{--}15\text{ seconds}$, and possess equal anteroposterior and transverse chest diameters ($1:1$ ratio) until approximately age $6$.

Which assessment findings signal acute respiratory distress in an infant?

Nasal flaring, grunting, sternal/intercostal retractions, or apneic pauses exceeding $15\text{--}20\text{ seconds}$.

How does pregnancy alter maternal respiratory anatomy and physiology?

The costal angle widens by approximately $50\%$, tidal volume increases by $40\%$, and breathing becomes deeper to accommodate the growing fetus pushing against the diaphragm.

What typical thoracic and pulmonary changes occur as part of normal aging in older adults?

An increased anteroposterior chest diameter (barrel-like appearance), kyphosis, prominent bony landmarks from diminished subcutaneous tissue, decreased chest expansion from loss of lung elasticity and calcification of costal cartilages, and increased fatigue during deep breathing.

Which abnormal respiratory waveform is illustrated below, characterized by regular waxing and waning depth followed by a period of apnea?

Cheyne-Stokes breathing (associated with severe neurological injury, stroke, or head trauma, typically cycling over $30\text{--}45\text{ seconds}$ before an apneic pause).

Which irregular breathing pattern is shown here, presenting with groups of 3 to 4 normal breaths followed by irregular periods of apnea?

Biot respiration (seen in head trauma, brainstem lesions, and severe neurological damage).

How do tachypnea and hyperventilation differ from each other?

Both are rapid and regular, but tachypnea is shallow ($> 24/\text{min}$), whereas hyperventilation is characterized by both increased rate and increased depth.

What are the key early ('UP') versus late ('LOW') signs of impaired gas exchange?

Early signs reflect compensatory acceleration: tachypnea, tachycardia, restlessness, increased blood pressure, and pale skin/membranes. Late signs reflect decompensation and failure: confusion/stupor, cyanosis, bradypnea, bradycardia, hypotension, and cardiac dysrhythmias.

Why is restlessness prioritized over cyanosis when monitoring a patient for hypoxia?

Restlessness is the earliest clinical manifestation of tissue hypoxia resulting from compensatory mechanisms; cyanosis is a late sign of physiological decompensation, and intervention must occur before cyanosis develops.

What causes crackles (rales), wheezes, and rhonchi, and when are they typically heard during the respiratory cycle?

Crackles are discontinuous popping sounds (like Velcro) heard predominantly on inspiration caused by fluid in the alveoli (e.g., pneumonia, pulmonary edema); wheezes are continuous high-pitched musical sounds heard mainly on expiration caused by air passing through narrowed airways (e.g., asthma, COPD); rhonchi are low-pitched snoring/rumbling sounds caused by secretions in large airways that frequently clear with coughing.

What is stridor, what causes it, and what is its clinical urgency?

Stridor is a harsh, high-pitched crowing sound heard on inspiration caused by acute upper airway obstruction (such as croup, epiglottitis, or a foreign object); it is a life-threatening emergency requiring immediate assessment.

What clinical position is illustrated below, and what does its presence indicate?

The tripod position (leaning forward with hands/elbows braced on knees); it helps open the chest and optimize accessory muscle use during severe respiratory distress (e.g., asthma, COPD) and indicates the patient requires immediate intervention.

What are the clinical hallmarks of chronic bronchitis according to lecture notes?

A ventilation defect involving infection and narrowing of the trachea and large bronchi with marked mucus production, presenting with a cough lasting up to $3\text{ months}$, thick sputum, postnasal drip, fatigue, and hypoxemia.

What pathophysiological changes and clinical signs characterize pulmonary emphysema?

A ventilation defect involving loss of lung elasticity, permanent destruction and enlargement of alveoli, and $CO_2$ retention (which can cause confusion), with $80\text{--}90\%$ of cases caused by smoking. Classic signs include dyspnea, barrel chest, difficult exhalation, clubbing, weight loss, and shallow rapid breathing.

Which medical conditions can cause a patient to develop a barrel chest ($1:1$ AP-to-transverse ratio)?

Conditions causing long-term chronic hyperinflation, specifically emphysema, chronic asthma (particularly in children), and cystic fibrosis.

What is atelectasis, why does it commonly occur postoperatively, and how is it prevented?

Atelectasis is the collapse of alveoli or a lung lobe; postoperatively, anesthesia and shallow breathing allow mucus to plug airways and deflate alveoli. It is prevented through early ambulation and incentive spirometry.

What assessment findings are typical of lobar pneumonia?

Tachypnea, decreased expansion on the affected side, fine-to-medium crackles, fever and chills, dullness to percussion, purulent or rust-colored/blood-tinged sputum, increased tactile fremitus, and bronchial breath sounds over the periphery.

What three pathophysiologic changes cause airflow obstruction during an asthma attack?

Bronchospasm (smooth muscle tightening), mucosal inflammation/edema, and thick mucus hypersecretion in the bronchioles.

Why is a pulmonary embolism (PE) considered a perfusion problem, and what are its critical clinical signs?

A thrombus (such as a DVT), fat, or air embolus blocks pulmonary blood flow while ventilation continues normally. Cardinal signs include sudden sharp stabbing chest pain on inspiration, sudden air hunger, distended neck veins, and an overwhelming feeling of impending doom.

What is the hallmark assessment sign of acute pulmonary edema, and what is the primary nursing action?

Pink, frothy sputum accompanied by severe dyspnea that worsens when lying flat; the primary nursing intervention is to immediately sit the patient upright.

What pathophysiological mechanism creates a tension pneumothorax, and what is its major warning sign?

Air enters the pleural space on inspiration but cannot escape, building positive pressure that collapses the lung and compresses the heart and great vessels, precipitously dropping cardiac output. Tracheal deviation toward the unaffected side is a critical late warning sign.

Which congenital chest wall deformity is depicted in the figure below, known as 'funnel breast'?

Pectus excavatum (a sunken sternum depression beginning at the $2\text{nd}$ intercostal space and deepest at the xiphoid-sternal junction, most noticeable on inspiration).

Which structural chest wall abnormality is shown below, known as 'pigeon breast'?

Pectus carinatum (a forward protrusion of the sternum with ribs sloping backward).

What spinal deformity is illustrated below, and at what curvature threshold does it threaten cardiopulmonary function?

Scoliosis (an abnormal lateral S- or C-shaped curve of the spine with asymmetric shoulders and hips); curves greater than $45^\circ$ can reduce lung volume and significantly impair cardiopulmonary function.

What nursing interventions comprise the 'I COUGH' postoperative respiratory program?

Incentive spirometry, Coughing & deep breathing, Oral care, Understanding (patient & staff education), Get out of bed at least $\ge 3\text{ times/day}$, and Head of bed elevated.

Why is regular oral care specifically emphasized as a strategy to prevent hospital-acquired pneumonia?

Brushing teeth lowers the bacterial load in the oral cavity by approximately $30\%$, thereby preventing microaspiration of mouth pathogens into the lungs during sleep.

What is the proper technique and physiological purpose of pursed-lip breathing?

Inhale slowly through the nose, purse the lips as if whistling, and exhale slowly for twice as long as inhalation; this maintains positive airway pressure to prevent airway collapse and purge trapped air.

How are primary, secondary, and tertiary prevention defined in respiratory health promotion?

Primary prevention prevents disease onset (e.g., smoking cessation, PPE, vaccines, I COUGH); secondary prevention screens for early detection (e.g., TB skin tests, chest X-rays, Lung Function Questionnaire); tertiary prevention manages diagnosed chronic conditions to optimize function (e.g., COPD breathing exercises).