Respiratory Assessment: Anatomy, Physiology, and Clinical Evaluation

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Respiratory System Overview

Key Terms

The respiratory system is essential for gas exchange, maintaining homeostasis, and supporting cellular metabolism. Understanding key terminology is foundational for effective assessment and clinical practice.

Respiration: The process of gas exchange between the atmosphere and body cells.
Ventilation: Movement of air into and out of the lungs.
Perfusion: The flow of blood through the pulmonary capillaries.
Dyspnoea: Difficulty or labored breathing.
Hypoxaemia: Low oxygen levels in the blood.
Hypercapnia: Elevated carbon dioxide levels in the blood.
Tachypnoea: Abnormally rapid breathing.
Haemostasis: The process of stopping bleeding; in respiratory context, maintaining blood stability.
Haemoptysis: Coughing up blood from the respiratory tract.
Pulse oximetry: Non-invasive measurement of oxygen saturation in the blood.
Arterial blood gases (ABG): Laboratory test measuring oxygen, carbon dioxide, and pH in arterial blood.
Respiration rate: Number of breaths per minute.

Functions of the Respiratory System

The respiratory system performs several vital functions to maintain physiological balance and support life.

Oxygen Supply: Delivers oxygen to body tissues for energy production.
Carbon Dioxide Removal: Eliminates CO2, a waste product of metabolism.
Homeostasis: Maintains acid-base balance in arterial blood by regulating CO2 and O2 levels.
Heat Exchange: Assists in thermoregulation (less significant in humans).

Equation for Acid-Base Balance:

This equation illustrates how CO2 affects blood pH.

Structures of the Respiratory System

Major Anatomical Components

The respiratory system is divided into upper and lower segments, each with specialized structures and functions.

Upper Respiratory System: Nose, mouth, pharynx, larynx
Lower Respiratory System: Trachea, bronchi, lungs, pleurae, alveoli

Example: The acinus is the functional unit of the lung, consisting of bronchioles, alveolar ducts, alveolar sacs, and alveoli, where gas exchange occurs.

Upper Respiratory System

Nose

The nose is the first segment of the respiratory system, responsible for filtering, warming, and humidifying inspired air.

Anatomy	Structure	Function	Developmental Considerations
Nose	Upper third is bone; rest is cartilage. Nasal cavity divided by septum. Contains olfactory receptors and paranasal sinuses.	Warms, filters, humidifies air. Cilia move debris out of airways.	Sinus openings narrow in children, increasing risk of inflammation. Sphenoid sinus develops in adolescence. Nasal stuffiness common in pregnancy due to increased vascularity.

Mouth

The mouth serves as both a digestive and respiratory passage, containing structures that aid in taste, digestion, and airway protection.

Anatomy	Structure	Function	Developmental Considerations
Mouth	Contains three pairs of salivary glands (parotid, submandibular, sublingual). Tongue is striated muscle.	Taste sensation. Saliva lubricates food, starts digestion, cleans and protects mucosa.	Salivation starts at 3 months. Young children have relatively large tongues. Older adults may have atrophic tissue and diminished sensation, increasing risk for infection and malnutrition.

Pharynx and Larynx

The pharynx and larynx are critical for both respiratory and digestive pathways, and for sound production.

Anatomy	Structure	Function	Developmental Considerations
Pharynx and Larynx	Extends from base of skull to sixth cervical vertebra. Includes nasal, oral, and laryngeal pharynx.	Pharynx: respiratory/digestive pathway. Larynx: sound production and airway protection.	In children, the airway is more anterior and the narrowest portion is below the glottis. Cricoid cartilage is the narrowest part in children under 10 years.

Lower Respiratory System

Thoracic Cage and Lungs

The thoracic cage protects the lungs and supports respiration. The lungs are paired organs with distinct lobes and pleural coverings.

Right lung: Three lobes; shorter due to liver position.
Left lung: Two lobes; narrower due to heart position.
Pleurae: Visceral and parietal layers with lubricating fluid to reduce friction.

Trachea and Bronchial Tree

The trachea and bronchial tree conduct air to the lungs and filter particulates.

Trachea: 10-11 cm long, anterior to esophagus.
Bronchi: Right main bronchus is shorter, wider, and more vertical than the left.
Dead space: Air in trachea/bronchi not available for gas exchange (~150 mL).
Bronchial tree: Lined with goblet cells that secrete mucus.

Developmental Considerations

Infants and Children

Smaller airways increase risk of obstruction.
Sinus development continues into adolescence.
Large tongue and anterior airway position affect airway management.

Pregnant Women

Increased vascularity may cause nasal congestion.
Elevated diaphragm affects lung capacity.

Older Adults

Atrophic mucosa increases infection risk.
Diminished taste and salivation may contribute to malnutrition.

Respiratory Assessment

Collection of Subjective Data

Subjective data involves patient-reported symptoms and history.

Anatomy	Subjective Data Collection
Nose	Discharge, frequent colds, sinus pain, trauma, epistaxis, allergies, altered smell
Mouth and Throat	Sores/lesions, sore throat, bleeding gums, toothache, hoarseness, dysphagia, altered taste, smoking/alcohol, dental care

Collection of Objective Data

Objective data is gathered through physical examination techniques.

Inspection: Observe thoracic cage, skin color, and breathing pattern.
Palpation: Assess chest expansion, tactile fremitus, and detect masses.
Percussion: Evaluate lung fields and diaphragmatic excursion.
Auscultation: Listen for breath sounds and identify abnormal (adventitious) sounds.

Types of Breath Sounds:

Bronchial: Loud, high-pitched, heard over trachea.
Bronchovesicular: Moderate pitch, heard over major bronchi.
Vesicular: Soft, low-pitched, heard over peripheral lung fields.

Adventitious Sounds: Crackles (rales), wheezes, stridor, and others indicate pathology.

Abnormal Findings

Thoracic Deformities: Barrel chest, scoliosis, kyphosis
Respiratory Patterns: Bradypnoea, hypoventilation, Cheyne-Stokes, Biot's respiration
Lung Sounds: Discontinuous (crackles), continuous (wheezes, stridor)
Respiratory Distress: Dyspnea, abnormal respiratory rates, head bobbing, tracheal tugging, cyanosis, chest pain, hypotension, persistent cough

Pharmacology: Inhaled Medications

Metered Dose Inhalers (MDI)

MDIs deliver precise doses of medication directly to the lungs, commonly used for conditions like asthma and COPD.

Salbutamol: A bronchodilator that relaxes smooth muscle and relieves bronchoconstriction.
Spacer Devices: Improve medication delivery and reduce oropharyngeal deposition.

Example: Administration of an MDI using a spacer is recommended for optimal drug delivery, especially in children and older adults.

Additional info: Academic context and expanded explanations have been added to ensure completeness and clarity for college-level Anatomy & Physiology students.