Alteration in Ventilation Part One

Critical care - Slide 1 to 136

Larynx

Located at the top of the trachea; houses vocal cords; transition point between the upper and lower airways; composed of nine cartilage segments (largest is the thyroid cartilage).

Vocal cords

Folds within the larynx essential for phonation; housed in the larynx.

Thyroid cartilage

Largest cartilage of the larynx.

Epiglottis

Flap of tissue that closes over the larynx during swallowing to prevent aspiration.

Valsalva maneuver

Technique involving a sudden increase in intra-abdominal and intrathoracic pressure; can reduce venous return and blood flow.

Carina

Point where the trachea divides into the right and left main bronchi.

Right mainstem bronchus

Right primary bronchus; shorter, wider, and more vertical than the left.

Lobar bronchi

Bronchi that supply the lobes of the lungs (second-order bronchi).

Tertiary bronchi

Third-order bronchi within the bronchial tree.

Terminal bronchioles

Smallest airways without an alveolus; lead to respiratory bronchioles.

Respiratory bronchioles

Bronchioles involved in gas exchange.

Alveolar ducts

Passages connecting respiratory bronchioles to alveoli.

Alveoli

Gas exchange units of the lungs; site of oxygen and carbon dioxide diffusion; contain macrophages. Endpoints of the respiratory tract.

Alveolar macrophages

Macrophages in alveoli that phagocytose debris and pathogens.

Type I alveolar cells

Cells forming the alveolar wall through which gas exchange occurs.

Type II alveolar cells

Cells that produce surfactant to coat the alveoli and reduce surface tension.

Surfactant

Lipid-protein coating that lowers surface tension in alveoli, aiding expansion and preventing collapse.

Alveolar collapse

Collapse of alveoli due to injury or surfactant deficiency, impairing gas exchange.

Bony thorax

Skeletal frame of the chest including clavicles, sternum, scapulae, ribs, and thoracic vertebrae.

Ribs

12 pairs forming chest wall; first seven attach to the sternum; 8–10 attach to ribs above; 11–12 are floating ribs.

Diaphragm

Primary inspiratory muscle; contracts to descend during inhalation, creating negative pressure.

Inhalation

Phase of breathing when the diaphragm and accessory muscles contract, drawing air into the lungs.

Exhalation

Breathing out; inspiratory muscles relax and the lungs recoil, expelling air.

Intrapleural pressure

Pressure in the pleural space between visceral and parietal pleura.

Intra-alveolar pressure

Pressure inside the alveoli.

Intra-thoracic pressure

Pressure within the entire thoracic cavity.

Ventilation

Movement of air into and out of the pulmonary airways and alveoli.

Pulmonary perfusion

Blood flow from the right heart through the lungs to the left heart.

Diffusion

Gas movement across a semipermeable membrane from high to low concentration between alveoli and capillaries.

External respiration

Gas exchange between the atmosphere and the blood in the lungs.

Oxyhemoglobin

Oxygen bound to hemoglobin in red blood cells.

PaO2

Partial pressure of arterial oxygen in the blood.

Internal respiration

Oxygen release by red blood cells to tissues and CO2 uptake by blood.

Pulmonary capillaries

Capillary network surrounding alveoli where gas exchange occurs.

Pulmonary arteries

Carry deoxygenated blood from the right ventricle to the lungs.

Pulmonary veins

Carry oxygenated blood from the lungs to the left atrium.

Visceral pleura

Membrane covering each lung.

Parietal pleura

Membrane lining the thoracic cavity.

Pleural fluid

Fluid between the pleural layers allowing smooth sliding of the lungs.

Pleura pain (pleuritis)

Nerve endings in parietal pleura transmit pain during inflammation.

Type I alveolar cells

Alveolar cells that form the wall for gas exchange.

Type II alveolar cells (surfactant cells)

Cells that secrete surfactant to reduce surface tension.

Surfactant

Lipid-protein substance reducing alveolar surface tension to prevent collapse.

Gas exchange units

Alveoli where oxygen and carbon dioxide exchange occurs.

Carina

Branch point where the trachea divides into the main bronchi.

Pneumothorax

Air in the pleural space that can cause lung collapse.

Pulmonary artery

Artery carrying deoxygenated blood from the heart to the lungs.

Pulmonary vein

Vein carrying oxygenated blood from the lungs to the heart.

Pleuritis

Inflammation of the pleura often causing sharp chest pain on breathing.

Pulmonary hypertension

Elevated blood pressure within the pulmonary arteries.

Oxygen therapy

Treatment delivering supplemental oxygen to treat hypoxemia.

Nasal cannula

Low-flow oxygen delivery device placed at the nostrils.

FiO2 (Fraction Inspired Oxygen)

Concentration of oxygen in inspired air; varies with device and flow.

Low-flow systems

Oxygen delivery methods that mix with room air (e.g., nasal cannula, simple mask).

High-flow systems

Deliver a specified, constant oxygen concentration independent of breathing pattern (e.g., Venturi mask).

CPAP

Continuous Positive Airway Pressure; maintains a single positive pressure to keep airways open.

BiPAP

Bilevel Positive Airway Pressure; provides two levels of pressure for inhalation and exhalation.

Oximetry (SpO2)

Noninvasive measurement of arterial oxygen saturation.

Pulse oximetry

Noninvasive method to measure SpO2 using a sensor on the body.

EtCO2 (End-tidal CO2)

Carbon dioxide concentration at the end of an exhaled breath; monitored by capnography.

Capnography

Monitor or waveform showing EtCO2 over time.

ABG (Arterial Blood Gas)

Blood test measuring pH, PaO2, PaCO2, and bicarbonate to assess oxygenation and acid-base status.

Allen’s test

Assessment of collateral circulation to the hand before radial artery puncture.

Radial artery

Artery commonly used for arterial blood gas sampling.

PAWP/PCWP (Pulmonary Capillary Wedge Pressure)

Left atrial pressure surrogate obtained via Swan-Ganz catheter to assess LV filling.

Swan-Ganz catheter

Pulmonary artery catheter used to measure hemodynamic parameters including PCWP.

Left ventricular end-diastolic pressure (LVEDP)

Pressure in the left ventricle at end of diastole; approximated by PCWP.

Pulmonary angiography

X-ray imaging of pulmonary vasculature to diagnose clots or vascular anomalies.

CT pulmonary angiography (CTPA)

Contrast-enhanced CT used to diagnose pulmonary embolism.

Ventilation-Perfusion (V/Q) scan

Nuclear medicine study assessing ventilation and perfusion to detect mismatches and emboli.

Ventilation-perfusion ratio (V/Q ratio)

Relationship of ventilation to perfusion; normally about 0.8 (4:5).

Shunt

Blood bypassing oxygenation areas in the lungs, causing unoxygenated blood to circulate.

Dead-space ventilation

Ventilation without perfusion; air reaching alveoli that are not perfused.

Silent unit

Coexistence of shunt and dead-space ventilation; little or no ventilation and perfusion.

V/Q mismatch

Discrepancy between ventilation and perfusion causing impaired gas exchange.

Oxyhemoglobin saturation (SpO2)

Proportion of hemoglobin that is bound with oxygen; measured by pulse oximetry.

HCO3- (Bicarbonate)

Buffer in blood; part of acid-base balance; regulated by kidneys and lungs.

pH

Measure of acidity/alkalinity of blood; normal ~7.35-7.45.

PaCO2

Partial pressure of carbon dioxide in arterial blood.

PaO2

Partial pressure of oxygen in arterial blood.

Respiratory acidosis

Acidosis due to hypoventilation increasing PaCO2.

Respiratory alkalosis

Alkalosis due to hyperventilation lowering PaCO2.

Metabolic acidosis

Acid-base disorder with low pH and low HCO3- due to increased acid or bicarbonate loss.

Metabolic alkalosis

Elevated pH due to increased bicarbonate or loss of hydrogen ions.

Hypoventilation

Inadequate ventilation causing CO2 retention and acidosis.

Hyperventilation

Excessive ventilation causing CO2 loss and alkalosis.

Pleuritic pain

Sharp chest pain that worsens with breathing; often due to pleural inflammation.

Orthopnea

Shortness of breath when lying flat; relieved by sitting up.

Sputum

Mucus produced by the respiratory tract; color and amount provide infection clues.

Dyspnea

Subjective sensation of difficult or uncomfortable breathing.

Wheezing

High-pitched whistling sound during breathing, often with obstruction.

Incentive spirometry

Device and technique to encourage deep breaths to prevent atelectasis.

Postural drainage

Positioning to use gravity to drain secretions from lungs.

Chest physiotherapy (CPT)

Manual percussion and chest therapy to loosen mucus.

High Frequency Chest Wall Oscillation (HFCWO)

Vest therapy delivering pulses to loosen secretions.

Oscillating Positive Expiratory Pressure (OPEP)

Handheld device creating resistance/vibration to clear mucus.

Tracheostomy tube

Tube inserted through the neck into the trachea to maintain airway.

Endotracheal tube

Tube inserted through mouth or nose into the trachea for airway and ventilation.

Nasotrachael tube

Common term for nasotracheal tube used during anesthesia.

Oropharyngeal airway

Airway adjunct placed in the mouth to prevent tongue obstruction.