Mechanical Ventilation Chapter 11.

Ventilation

The process of moving gas (air) in and out of the lungs.

Respiration

The physiologic process of using O2 by the tissues at the cellular level.

Role of Ventilation

Supports gas exchange and maintains acid-base (pH) balance.

Pressure Gradient

The difference in pressure that drives airflow into and out of the lungs.

Atmospheric Pressure (Patm)

Pressure around us, usually 760 mmHg at sea level.

Alveolar Pressure (Palv)

Pressure inside the lungs, changes during inhalation and exhalation.

Intrapleural Pressure (Ppl)

Pressure in the space between the lung and chest wall, normally slightly negative.

Inspiration

The phase of ventilation where pressure inside the lungs is lower than atmospheric pressure.

Expiration

The phase of ventilation where pressure inside the lungs is higher than atmospheric pressure.

Negative Pressure Ventilation

A mechanism where chest expansion lowers lung pressure, causing air to flow in.

Positive Pressure Ventilation

A mechanism where a machine pushes air into the lungs, raising alveolar pressure.

Work of Breathing

The effort required to move air in and out of the lungs.

Airway Resistance

The opposition to airflow in the respiratory tract caused by airway diameter.

Surface Tension

The inward pull created by liquid in the alveoli that tries to collapse them.

Surfactant

A substance produced by Type II alveolar cells that reduces surface tension.

Active Expiration

Involves muscles like internal intercostals and abdominal muscles to force air out.

Mechanical Work of Breathing

Describes the forces needed to achieve ventilation against resistance.

Elastance

The lung's ability to recoil after being stretched.

Compliance

The lung's ability to stretch and increase in volume.

Factors Opposing Ventilation

Include airway resistance and surface tension that increase work of breathing.

Asthma

A condition marked by narrowed airways and increased airway resistance.

Acute Respiratory Distress Syndrome (ARDS)

A condition characterized by damage to alveolar cells and loss of surfactant.

Inhalation Mechanics

Diaphragm contracts and external intercostal muscles lift ribs, expanding the chest cavity.

Exhalation Mechanics

Diaphragm relaxes, and lungs recoil, raising alveolar pressure to push air out.

Gas Exchange

The process of oxygen entering the blood and carbon dioxide being expelled from it.

Tripod Position

A posture adopted by patients with breathing difficulties to ease respiration.

Shortness of Breath (SOB)

A subjective feeling of not being able to get enough air.

Tidal Volume

The volume of air inhaled or exhaled during normal breathing.

Airway Diameter

The size of the airways affecting the resistance to airflow.

Laminar Flow

Smooth, streamlined airflow that minimizes resistance.

Turbulent Flow

Irregular, swirling airflow that increases resistance.

COPD

Chronic obstructive pulmonary disease, a condition leading to airway narrowing.

Mechanical Ventilator

A device that provides positive pressure ventilation to assist breathing.

Signs of Respiratory Distress

Includes increased work of breathing, changes in respiratory rate, and low SpO2 levels.

Bronchodilators

Medications used to relax and open airways in conditions like asthma.

Ventilator Settings

Adjustments made by respiratory therapists to ensure proper airflow and pressure.

Patient Education

Coaching patients about their breathing and how to manage respiratory issues.