Mechanical ventilation

Overview

Mechanical ventilation is a therapeutic method that assists or takes over breathing when you’re unable to do so on your own. This support might be necessary during surgery or if your lungs are not functioning properly. The purpose of mechanical ventilation is to maintain open airways, deliver oxygen, and remove carbon dioxide.

Mechanical ventilation acts as a form of life support, stabilizing you while other treatments and medications work to address the underlying condition. 

A ventilator, which is the machine used in this process, helps manage your breathing by:

• Delivering oxygen to your lungs
• Removing carbon dioxide (CO2) from your lungs
• Providing pressure to keep the small air sacs in your lungs (alveoli) from collapsing

The settings on the ventilator can be adjusted according to your specific needs.

Mechanical ventilation is often accompanied by intubation, but they are distinct procedures. Intubation involves inserting a tube into the airway (trachea) through the throat, which is then connected to a ventilator. In some cases, a face mask can be used instead, allowing for ventilation without intubation.

The duration of mechanical ventilation varies based on the underlying condition, ranging from hours to days, weeks, or in rare instances, months or even years. The goal is to minimize the time spent on a ventilator. Healthcare providers will regularly evaluate your ability to breathe independently. If prolonged ventilation is necessary—typically after about two weeks—a healthcare provider may transition from an endotracheal tube to a tracheostomy, which involves placing a tube directly into the neck.

Types

Modern mechanical ventilators operate using positive pressure to deliver air into your lungs. Positive pressure ventilation can be classified into two types: invasive and noninvasive.

• Invasive mechanical ventilation: This involves placing a tube in your airway that is connected to the ventilator. The tube may be inserted through your mouth (intubation) or placed directly into your neck (tracheostomy).
• Noninvasive ventilation: This method uses a face mask connected to the ventilator. The mask is secured with straps to ensure a tight fit, allowing the ventilator to push air into your lungs. Noninvasive ventilation includes devices such as CPAP (Continuous Positive Airway Pressure) or BiPAP (BiLevel Positive Airway Pressure), which are commonly used at home.

Reasons for undergoing the procedure

Healthcare providers use mechanical ventilators to assist with breathing when you are unable to breathe on your own. Mechanical ventilation serves several critical functions:

• It provides oxygen to your lungs.
• It helps remove carbon dioxide to prevent its buildup.
• It maintains pressure to prevent parts of your lungs from collapsing.

Mechanical ventilation may be required in various situations, including:

• Surgery: General anesthesia can impair your ability to breathe adequately on your own.
• Lung conditions or infections: Certain respiratory conditions may necessitate mechanical support.
• Medical emergencies: Situations that block the airway or hinder breathing can require mechanical ventilation.
• Neurological conditions: Conditions affecting the brain may disrupt communication with the rest of the body, affecting your ability to breathe properly.
• Blood gas imbalances: Conditions that result in high levels of carbon dioxide (hypercapnia) or low levels of oxygen (hypoxemia) may need mechanical ventilation.
• Aspiration prevention: To avoid accidental aspiration of fluids into the lungs.

Certain conditions that might necessitate mechanical ventilation include:

• Acute Respiratory Distress Syndrome (ARDS)
• Chronic Obstructive Pulmonary Disease (COPD)
• COVID-19 and other respiratory illnesses
• Pneumonia 
• Anaphylaxis
• Coma
• Stroke
• Traumatic brain injury

Risks

While healthcare providers take measures to minimize complications associated with mechanical ventilation, some risks can still occur:

• Bacterial infections: The tube used for ventilation can introduce bacteria into the lungs, potentially leading to infections like ventilator-associated pneumonia (VAP), which is typically treated with antibiotics.
• Lung damage: The pressure exerted by the ventilator can cause harm to the lungs.
• Collapsed lung: Weak areas of the lung may develop a hole, leading to a pneumothorax, or collapsed lung.
• Heart and blood flow changes: Mechanical ventilation can impact heart function, potentially lowering blood pressure or increasing heart rate. This can reduce the amount of oxygen delivered to the blood, despite adequate oxygen levels in the lungs.
• Difficulty weaning off the ventilator: In some cases, prolonged use of a ventilator may require transitioning from an endotracheal tube to a tracheostomy, where a tube is inserted through a small incision in the neck.
• Prolongation of the dying process: In situations where recovery is unlikely, mechanical ventilation may extend the dying process and cause unnecessary suffering. Healthcare providers will assist in making decisions regarding ventilation in such cases.

Before the procedure

The healthcare provider will start invasive mechanical ventilation by:

• Administering medication to relax you (sedation) and to prevent movement (paralytic). While you will likely remain sedated throughout, the paralytic effect will diminish once the ventilator is in place.
• Inserting an endotracheal (ET) tube through your mouth into your trachea (the airway leading to your lungs).
• Connecting the ET tube to a ventilator, which will assist with your breathing until your medical team determines that you can breathe independently again.

These steps outline the general process for starting mechanical ventilation, though specific procedures may vary based on your individual circumstances and whether the situation is an emergency.

During the procedure

While you’re on a ventilator, healthcare providers will carry out additional procedures to manage your condition and prevent complications:

• Bronchoscopy: A bronchoscope, a small, lighted camera, will be inserted through the breathing tube to examine your airways and lungs. This may involve taking samples of mucus or tissue for further testing.
• Suctioning: To keep your airways clear, a catheter will be inserted into the breathing tube to remove mucus or secretions. This procedure might induce coughing or gagging.
• Medications: Aerosolized medications will be administered through your breathing tube to target your lungs directly. Additionally, intravenous (IV) medications will be given to you through a vein.
• Monitoring: You will be connected to machines that track vital signs, including blood pressure, heart rate, respiratory rate (breaths per minute), and oxygen levels. Your healthcare providers may also use chest X-rays and blood tests to assess lung function and gas levels.
• Mobilization: Your healthcare providers will frequently reposition you, including sitting you up and occasionally assisting with walking. 
• Nutrition and fluids: As you cannot eat or drink normally while intubated, liquid nutrition will be provided via a feeding tube inserted through your nose into your stomach, and fluids will be administered through an IV.

Throughout your time on the ventilator, your healthcare provider will strive to keep you as awake and comfortable as possible, using medications to manage pain and anxiety. You may be conscious but feel drowsy or disoriented. In more severe cases, deeper sedation might be necessary for your comfort and recovery, with your arms possibly restrained to prevent accidental dislodging of the tube.

After the procedure

Before discontinuing mechanical ventilation, your healthcare team will perform tests to assess your ability to breathe independently, with the endotracheal (ET) tube still in place. Once your condition has improved and you show signs of being able to breathe on your own, the ET tube will be removed, concluding your mechanical ventilation.

This process, known as extubation, may leave you with a sore throat, mouth discomfort, or a hoarse voice. After extubation, your healthcare provider might place you on alternative breathing support, such as noninvasive ventilation with a mask or an oxygen mask. In some cases, if you cannot maintain adequate breathing, reintubation and mechanical ventilation may be required.

Outcome

Mechanical ventilation offers several key benefits:

• Reduced breathing effort: It eases the burden of breathing, allowing your body to concentrate on recovering from infections or other conditions.
• Oxygen and carbon dioxide management: It ensures adequate oxygen delivery while effectively removing carbon dioxide.
• Prevention of lung collapse: The ventilator provides pressure to keep the small air sacs in your lungs from collapsing.
• Airway maintenance: It helps keep your airways open.

The recovery duration from mechanical ventilation varies based on the underlying condition and the length of time you were on the ventilator. Your healthcare provider will provide guidance on what to expect during recovery and how to manage your care.