Mechanical Ventilator

🫁 Mechanical Ventilator: Overview, Types, and Functions

A mechanical ventilator is a life-support device used to assist or replace spontaneous breathing when patients are unable to breathe adequately on their own. This can be due to respiratory failure, surgery, trauma, or neurological conditions.

🔧 What is a Mechanical Ventilator?

A mechanical ventilator is a machine that moves breathable air in and out of the lungs. It delivers a set amount of oxygen and pressure to ensure adequate gas exchange (oxygen in, carbon dioxide out).

📋 Main Indications for Mechanical Ventilation

Acute respiratory failure (e.g., ARDS, COPD exacerbation)
During and after major surgery (especially under general anesthesia)
Neuromuscular disorders (e.g., Guillain-Barré, Myasthenia Gravis)
Severe trauma or head injury
Coma or decreased level of consciousness

🛠️ Types of Mechanical Ventilation

1. Invasive Ventilation

Delivered through an endotracheal tube (ETT) or tracheostomy.
Used in ICU settings or emergency care.

2. Non-Invasive Ventilation (NIV)

Delivered via face mask or nasal mask.
Common forms: CPAP (Continuous Positive Airway Pressure), BiPAP (Bilevel Positive Airway Pressure).

⚙️ Modes of Mechanical Ventilation

1. Volume-Controlled Ventilation (VCV)

Delivers a fixed tidal volume.
Used when precise control over lung volume is needed.

2. Pressure-Controlled Ventilation (PCV)

Delivers air until a preset pressure is reached.
Useful for protecting the lungs from high pressure.

3. Assist-Control (AC) Mode

Ventilator gives full support for every breath—either patient-initiated or machine-triggered.

4. SIMV (Synchronized Intermittent Mandatory Ventilation)

Allows spontaneous breathing between machine-delivered breaths.
Good for weaning off ventilation.

5. Pressure Support Ventilation (PSV)

Used mostly for weaning.
Patient breathes spontaneously, and the ventilator supports with pressure.

📈 Key Ventilator Settings

Parameter	Description
Tidal Volume (Vt)	Volume of air delivered per breath (6–8 mL/kg ideal body weight)
Respiratory Rate (RR)	Number of breaths per minute
FiO₂	Fraction of inspired oxygen (21–100%)
PEEP	Positive End-Expiratory Pressure (usually 5–10 cmH₂O)
Pressure Support	Helps spontaneous breaths with extra pressure

⚠️ Complications of Mechanical Ventilation

Ventilator-associated pneumonia (VAP)
Barotrauma (lung injury from excessive pressure)
Volutrauma (lung injury from high volumes)
Oxygen toxicity
Tracheal damage from prolonged intubation
Ventilator dependency or failure to wean

🔄 Weaning from Mechanical Ventilation

Weaning is the process of reducing ventilator support and transitioning the patient back to spontaneous breathing. Criteria for weaning include:

Stable hemodynamics
Adequate oxygenation (e.g., PaO₂ > 60 mmHg on FiO₂ ≤ 40%)
Normal mental status
Strong spontaneous respiratory effort

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Mechanical Ventilator