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Respiratory Functional Tests

Overview

• Test conducted by: Gabriela Jimborean, Alpar Csipor, Edith Simona Ianosi, Hedi Balogh, Mioara Szatmary

• Institution: Pneumology Department, UMFST Tg. Mureș

Components of Respiration

• External Respiration: Occurs in the thoraco-pulmonary apparatus.

• Gas Transport: Involves the cardiovascular system (heart, vessels, blood).

• Internal Tissue Respiration: Exchange between capillaries/interstitium and cells, includes:

  • Ventilation: Driven by impulses from the respiratory centers and contraction of respiratory muscles.

  • Pulmonary Perfusion: Supply of blood to the lungs.

  • Gas Exchange: At the level of the alveoli (MAC).

Evaluation Tests for Pulmonary Function

Types of Tests

• Ventilation Tests:

  • Pulmonary Volumes: Measures static lung volumes and flow rates.

  • Pulmonary Mechanics: Includes static and dynamic lung compliance, elastic recoil, and airway resistance to airflow.

• Bronchomotor Tests: Assesses airway responsiveness.

• Gas Diffusion Tests: Via MAC.

• Acid-Base Balance: Through gas exchange mechanisms.

• Muscle Work Tests: Assessing cardiac function.

• Pulmonary Circulation Study: Includes polysomnography, pletismography, gasometry, imaging tests (CT, PET), cardiac echo, EKG.

• Composite Indexes: BODE index, composite index (BMI, spirometry, walking tests).

• Indirect Assessments: Patient questionnaires (CAT, dyspnea scales).

Indications for Respiratory Function Tests

• Diagnosis: Of conditions with dominant functional aspects (asthma, COPD, fibrosis).

• Severity Assessment: Evaluates the functional deficit of respiratory conditions.

• Functional Status: Assessment pre/post-surgery.

• Diagnosis of Respiratory Insufficiency: Of pulmonary origin.

• Oxygen Therapy Indication: In cases of mechanical ventilation needs (invasive/non-invasive).

• Rehabilitation: Respiratory rehabilitation and physical exercise evaluation.

• Work Capacity Evaluation: Quality of life assessment (QOL).

• Screening: For individuals with increased risk (smokers, physically active employees, aviators, military personnel).

Spirometry

• Definition: Measures respiratory volumes and flow rates using flow-volume curves.

  • Predictive Database: Spirometers contain a database for reference predictive values based on variables like sex, age, height, weight, atmospheric conditions (BTPS).

Conditions for Spirometry

• Pre-conditions: Nothing by mouth, no stimulants/medications, no smoking 3 hours prior.

• Patient Preparation: Arrive via scheduled appointment, rest for 30 minutes prior to testing.

• Procedure: Conducted by trained assistants in a quiet environment, ensuring proper setup of equipment.

Forced Spirometry Technique

1. Patient breathes quietly through the mouthpiece (current tidal volume).

2. Following a deep inhalation, the patient exhales as fast and completely as possible.

3. The graphical record includes forced expiratory and inspiratory flow-volume curves.

Spirometry Contraindications

• Absolute Contraindications:

  • Severe respiratory insufficiency.

  • Hemoptysis.

  • Pneumothorax.

  • Uncontrolled cardiovascular diseases (recent heart attack, unstable angina).

  • Recent surgeries, facial trauma, retinal detachment.

Lung Capacity Measurements

• Vital Capacity (CV): Total volume of air expelled after maximum inhalation.

  • Force Vital Capacity (CVF): Volumes during forced expiration.

  • Normal Values: CVF decreases in obstructive diseases (e.g., emphysema, COPD).

Residual Volume (VR)

• Remains in the lungs after maximum expiration, which can increase or decrease in various diseases (e.g., emphysema, restrictive diseases).

Interpretation of Spirometry Results

• PEF (Peak Expiratory Flow) is significant for assessing air passage competency.

• Flow-Volume Curve Analysis: Changes in curve patterns suggest different types of ventilatory dysfunction (e.g., obstructive, restrictive).

• Diagnostic Indicators:

  • Obstruction: Decreased Flow Rates.

  • Restriction: Normal or Increased Flow Rates but reduced capacities.

Gas Exchange

• Factors Affected by MAC: Thickness, surface area, number of functional alveolar-capillary units influence gas exchange efficiency.

• Clinical Signs of Respiratory Insufficiency: Decreased oxygenation and potential for cyanosis, clinical signs like tachycardia, confusion.

Assessment Tools for Gas Exchange

• Arterial Blood Gases (ABG): Provides data on ventilation and condition of acid-base balance.

  • Responses to Treatment: Essential for assessing effectiveness in COPD, asthma, and other conditions.

Summary of Important Parameters

• Normal Values:

  • pH: 7.35 - 7.45

  • PaO2: 80 - 100 mmHg

  • PaCO2: 35 - 45 mmHg

  • HCO3: 22 - 28 mEq/L

This document summarizes key aspects of respiratory function tests, methods, interpretations, contraindications, and relevant conditions for a comprehensive understanding and study for examinations.