Oxygenation in Humans

Overview

This lecture introduces the fundamentals of oxygenation in the human body, covering respiratory anatomy, physiology, assessment, and common nursing interventions for oxygenation issues.

Oxygen: Definition and Importance

• Oxygen is a clear, odorless gas comprising 21% of air, essential for all living cells.
• Lack of oxygen leads to cell, tissue, and organism death.

Respiration and its Components

• Respiration is gas exchange between individual and environment, involving ventilation, alveolar-capillary gas exchange, transport, and systemic diffusion.
• Ventilation is air movement in and out of the lungs (breathing).
• Alveolar-capillary gas exchange is diffusion of oxygen and carbon dioxide between alveoli and pulmonary capillaries.
• Transport is movement of gases between lungs and tissues via blood.
• Systemic diffusion is gas exchange between systemic capillaries and tissues.

Respiratory System Structure

• Upper respiratory tract: mouth, nose, pharynx, larynx.
• Lower respiratory tract: trachea, bronchi, lungs, bronchioles, alveoli, pulmonary capillaries, pleural membranes.
• Air is warmed, humidified, and filtered in the nose; sneezing expels irritants.

Pulmonary Ventilation and Pressures

• Inspiration: diaphragm and intercostals contract, increasing thoracic cavity size, lowering intrapulmonary pressure, drawing in air.
• Expiration: relaxation of muscles, decreasing cavity size, raising pressure, expelling air.
• Intrapleural pressure is always slightly negative, keeping lungs inflated.

Lung Volumes and Compliance

• Tidal volume: normal air moved per breath (~500 mL in adults).
• Lung compliance: ease of lung inflation; decreases with aging.
• Atelectasis: lung tissue collapse.
• Lung recoil: lungs' tendency to collapse, important for expiration.
• Surfactant: substance reducing alveolar surface tension, prevents collapse.

Gas Exchange and Transport

• Diffusion: gases move from high to low concentration.
• Hemoglobin in red blood cells transports oxygen as oxyhemoglobin.
• Oxygen transport is affected by cardiac output, number of red blood cells, and hematocrit.

Factors Affecting Respiratory Function

• Age, environment (altitude, pollution), lifestyle, health status, medications, and stress can impact oxygenation.
• Aging and disease increase risk for respiratory issues.

Alterations in Respiratory Function

• Airway obstruction: caused by foreign bodies or secretions.
• Breathing patterns: include eupnea, tachypnea, bradypnea, apnea, and abnormal patterns (Kussmaul, Cheyne-Stokes, Biot's).
• Diffusion issues: hypoxemia (low blood oxygen), hypoxia (low tissue oxygen), cyanosis (bluish skin).
• Transport issues: conditions like heart failure or hypovolemia impair delivery.

Nursing Assessment and Diagnosis

• Assessment includes medical history, physical exam (inspection, palpation, percussion, auscultation), and diagnostics (sputum, blood tests, pulmonary function).
• Common diagnoses: ineffective airway clearance, impaired gas exchange, activity intolerance, anxiety.

Nursing Interventions and Therapies

• Promote oxygenation via deep breathing, coughing, hydration, medication, and incentive spirometers.
• Percussion, vibration, postural drainage remove lung secretions.
• Mucus clearance devices and oxygen therapy are used for excessive secretions or low oxygen.
• Oxygen devices: low-flow (nasal cannula, simple mask), high-flow (Venturi mask, aerosol mask).
• Nebulizers deliver medication in mist form for inhalation.
• Endotracheal intubation and tracheostomy maintain airway in severe cases; require suctioning and patient communication support.

Key Terms & Definitions

• Ventilation — movement of air in and out of the lungs.
• Alveolar-capillary gas exchange — diffusion of gases between alveoli and pulmonary capillaries.
• Tidal volume — normal air volume breathed in/exhaled per cycle.
• Atelectasis — collapse of lung tissue.
• Surfactant — substance reducing surface tension in alveoli.
• Oxyhemoglobin — compound of oxygen and hemoglobin in red blood cells.
• Hypoxemia — low oxygen in the blood.
• Hypoxia — insufficient oxygen in body tissues.
• Cyanosis — bluish discoloration due to low oxygen saturation.
• Eupnea — normal breathing.
• Tachypnea — rapid breathing.
• Bradypnea — slow breathing.
• Apnea — absence of breathing.

Action Items / Next Steps

• Review lecture notes and definitions.
• Practice respiratory assessment techniques.
• Familiarize yourself with oxygenation devices and their indications.
• Complete any assigned readings on respiratory care.

Certainly! Pulmonary edema is a condition where fluid accumulates in the alveoli (air sacs) of the lungs. This fluid buildup interferes with the normal gas exchange process between the alveoli and the pulmonary capillaries.

Here’s why hypoxemia is the correct answer:

• Hypoxemia means reduced oxygen levels in the blood.
• In pulmonary edema, the fluid in the alveoli creates a barrier that impairs the diffusion of oxygen from the alveoli into the blood.
• Because oxygen cannot efficiently pass through the fluid-filled alveoli, less oxygen enters the bloodstream, leading to low arterial oxygen levels.
• This directly causes hypoxemia.

In contrast:

• Hypoxia refers to insufficient oxygen at the tissue level, which can result from hypoxemia but is a broader term.
• Pulmonary edema primarily causes the initial problem of oxygen not entering the blood well, i.e., hypoxemia.

So, pulmonary edema impairs alveolar-capillary gas exchange, leading to hypoxemia as the primary risk.

Summary:

Let me know if you want me to explain more about pulmonary edema or related respiratory conditions!