التنفس والوظائف الرئوية

Respiratory System Function

• Breathing is crucial for oxygenation and CO2 exchange.
• Oxygenation involves taking in oxygen.
• Ventilation involves exchanging CO2.

Components Affecting Respiration

• Respiratory center
• Peripheral nerves
• Respiratory muscles
• Nerve-muscle connections
• Thoracic bones
• Airways
• Alveoli

Ventilatory Pump

• Bones, muscles, pleura, peripheral nerves, and airways, are key components.

Phrenic Nerves

• C3, C4, and C5 spinal nerves
• Control the diaphragm.

Lung Defects - Classification

• Obstructive: Expiratory flow is below normal. Anatomical site can be identified. Examples include cystic fibrosis, bronchitis, asthma, bronchiectasis, and emphysema.
• Restrictive: Lung volumes are reduced. Examples include neuromuscular diseases, cardiovascular diseases, pulmonary issues, trauma/chest wall dysfunction, and obesity

Restrictive Lung Disease - Types

• Lung: Interstitial pulmonary fibrosis (IPF), idiopathic, occupational, resection, irradiation.
• Pleural: Pleural effusion, pneumothorax, pleural fibrosis, pleural tumors, pleural thickening.
• Chest wall: Trauma, kyphoscoliosis, neuromuscular disease (e.g., myasthenia gravis [MG], Guillain-Barré syndrome [GBS]), severe obesity, and scleroderma.

Respiratory Failure - Causes

• Lung failure (Type I): Impaired diffusion, Shunt, Hypoxaemia.
• Pump failure (Type II): Hypoventilation, Ventilation-perfusion mismatch, Central depression of respiration, Respiratory muscle weakness, Hypercapnia

Oxygenation/Pulmonary Failure - Possible Causes

• Increased thickness of respiratory membrane.
• Alveolar filling.
• Pulmonary edema.

Ventilation Failure - Possible Causes

• Narrowed airways, preventing adequate air entry.
• Respiratory center suppression.
• Damage to phrenic nerves.
• Weakened muscles.
• Diaphragm damage.
• Thoracic bone damage.

Respiratory System - Key Elements

• Lungs: Involved in pulmonary function.
• Respiratory pump: Mechanism for ventilation.
• Pulmonary failure: Issues with oxygen exchange.
• Ventilatory failure: Breathing problems.
• Hypoxic respiratory failure: insufficient oxygen delivery.
• Hypercapnic respiratory failure: excessive carbon dioxide in the blood.

Lung Compliance

• Dynamic: Lung compliance during air movement.
• Static: Lung compliance during periods without gas flow (e.g., inspiratory pause).
• Decreased compliance linked to factors like supine position, various surgical interventions, chronic restrictive pathologies, and pneumothorax.

Resistance

• Resistance refers to obstacles in the airways impeding air flow.
• Normal resistance in adults is 1-8 cmH20/L/s.

Mechanical Ventilation (MV) Goals

• Control rate of alveolar ventilation.
• Maintain adequate oxygenation.
• Optimize carbon dioxide removal.
• Reduce work of breathing
• Optimize patient comfort
• Mitigate lung injury.
• Monitor parameters like Barotrauma, Volut, Atelectasis, and Biotrauma.

Spirometry - Goals

• Evaluate baseline lung function (pre-employment).
• Screen for undiagnosed lung diseases.
• Track disease progression and response to treatments.
• Assess severity of obstructive and restrictive lung diseases.
• Evaluate the response to bronchodilators.

Spirometry Considerations

• Patient preparation: Dietary restrictions, patient cooperation, vital signs, appropriate clothing.
• Instrumentation: Using proper spirometers and procedures, ensure consistent measurements, and identify potential issues.

Spirometry - Measurement Terms

• TLC: Total lung capacity.
• VC: Vital capacity.
• IC: Inspiratory capacity.
• FRC: Functional residual capacity.
• IRV: Inspiratory reserve volume.
• ERV: Expiratory reserve volume.
• RV: Residual volume.
• FVC: Forced vital capacity.
• FEV1: Forced expiratory volume in the 1st second.
• FEF25-75%: Forced expiratory flow.
• FEF25-75%: % Indicates the percent of forced expiratory flow rate within a specific time period.
• PEF, MEF: Peak expiratory flow, maximal expiratory flow.

Spirometry - Evaluation of Results

• Normal: Values fall within expected ranges.
• Obstructive: Decreased expiratory flow rates.
• Restrictive: Reduced lung volumes or capacity, often associated with slower expiratory flow rates in certain circumstances.
• Mixed: A combination of obstructive and restrictive patterns, resulting in a specific pattern in some cases.

Lung Pathology Features

• Emphysema: Enlarged air spaces in the lungs.
• Bronchiectasis: Irreversible dilation of bronchi.
• Cystic fibrosis: Genetic disorder affecting the lungs and other organs, involving excessive mucus production.
• Interstitial lung disease: Inflammatory or fibrotic tissue around alveoli (air sacs), leading to reduced ability to fill the lungs with air.
• Bronchitis: Inflammation and irritation of the bronchi, possibly leading to excessive mucous production.

Complications

• Atelectasis: Collapsed lung segments.
• Pleuritis: Lung/chest wall inflammation.
• Pleural effusion: Accumulation of fluid between lung layers.
• Pneumothorax: Air in the pleural space.
• Empyema: Pus buildup in the pleural cavity.
• Lung abscess: Cavity formation filled with pus in lung tissue
• Aspiration: Foreign materials lodged in airways.

Procedure - Spirometry

• Patients take deepest breath, exhale forcefully into spirometer.
• Sometimes, rapid inhalation (inspiration) follows exhalation.
• Quiet breathing may precede the forced maneuver.
• Procedure ends after 8 unsuccessful attempts, noting the inability.

Post-Bronchodilator Test

• Administered before another test round, to determine the reversibility of specific conditions.
• Diagnosing asthma versus chronic obstructive pulmonary disease (COPD).

Additional Factors Affecting Spirometry

• Age, height, and gender
• Presence of underlying conditions like disease or injuries

استكشف المعلومات المتعلقة بالوظائف التنفسية مثل FEV1%IVC والشعاب الهوائية. هذا الاختبار مناسب للطلاب والأطباء الذين يرغبون في فهم أفضل لحالات الانسداد والتقييد. احصل على تحدي معرفتك حول فسيولوجيا الجهاز التنفسي.