Modes of Ventilation: The Basics

Basic modes of ventilation can be mostly categorized into two separate groups:

• Control modes
• Spontaneous modes

Control modes exist to replace the whole process of breathing. When on a control mode, the ventilator completely controls all phases of a breath including:

1. Initiation: Breathing is no longer controlled by the chemoreceptors and diaphragm. The ventilator will push breaths into the lungs at the interval set by the clinician.
2. Inhalation: The amount of air pushed into the lungs is determined by what is set. The lungs will inflate because it is a sealed system.
3. Termination of inhalation: Once the set amount of air is pushed in, the ventilator will stop pushing air into the lungs.
4. Exhalation: The lungs will passively deflate as air moves from high pressure to low pressure.

The control mode is utilized for patients who are not able to breathe on their own or who are not breathing or compensating enough to support the body’s needs. Every single step in the breathing process is determined by what is set by the health care professional. Virtually nothing to do with the respiratory process is decided by the patient.

Spontaneous modes are exactly what the name suggests. They allow the patient to be much more involved in the breathing “decision-making process”. The patient can control much more of the pattern and size (or volume) of their breaths, and they can cycle through the phases of a breath based on what they want to do. Spontaneous modes are used in situations where patients have an intact drive to breathe—meaning they are still initiating breaths regularly and the physiological “trigger” in the brain is still functioning to initiate a breath (remember the chemoreceptors?). In spontaneous modes, the patient does have more control over their breathing pattern, but some aspects of the breath are still dependent on what is set on the ventilator and not fully patient-driven.