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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.