Intubation and Mechanical Ventilation

What is Intubation?

Intubation is a medical procedure where a tube (endotracheal tube) is inserted into the trachea (windpipe) through the mouth or nose. It is commonly performed to maintain an open airway or to administer oxygen, anesthetic gases, or medication directly into the lungs.

What is Mechanical Ventilation?

Mechanical ventilation is a life-support technique where a machine (ventilator) is used to assist or replace spontaneous breathing. It is used when a patient is unable to breathe adequately on their own due to a variety of conditions such as severe respiratory distress, injury, surgery, or critical illness.

Indications for Intubation and Mechanical Ventilation

• Airway Obstruction: Due to trauma, allergic reaction, or foreign body.
• Respiratory Failure: Conditions like COPD, ARDS (Acute Respiratory Distress Syndrome), pneumonia, or heart failure.
• Surgical Anesthesia: During general anesthesia to manage the airway and ensure controlled breathing.
• Neuromuscular Diseases: Such as ALS (Amyotrophic Lateral Sclerosis), which affects muscle control including breathing muscles.
• Severe Shock: Resulting in impaired oxygen delivery to tissues.

Procedure for Endotracheal Intubation

Preparation

1. Pre-Oxygenation: The patient is given oxygen to avoid hypoxia during the procedure.
2. Patient Positioning: The patient is typically placed in a supine position with the neck slightly extended to align the mouth, pharynx, and trachea.
3. Equipment Check: Ensure that the necessary equipment (laryngoscope, endotracheal tube, suction, ventilator) is ready.

Steps in Intubation

1. Sedation and Paralysis: Medications like sedatives (propofol, midazolam) and muscle relaxants (succinylcholine) are administered to relax the muscles and make the procedure smoother.
2. Visualization of the Airway:
   • A laryngoscope is inserted into the mouth to lift the tongue and visualize the vocal cords.
   • Once the vocal cords are seen, the endotracheal tube is passed through them into the trachea.
3. Tube Placement Confirmation:
   • Visual confirmation of the tube passing through the vocal cords.
   • Capnography (monitoring exhaled CO₂ levels).
   • Auscultation of the lungs and stomach.
   • Chest X-ray for final confirmation.
4. Tube Securing: The endotracheal tube is secured to prevent displacement.

Procedure for Mechanical Ventilation Setup

Types of Mechanical Ventilation

1. Invasive Ventilation: Involves the use of an endotracheal or tracheostomy tube. Full control or assistance is provided by the ventilator.
2. Non-Invasive Ventilation (NIV): Utilizes a mask that fits over the nose or mouth (e.g., CPAP or BiPAP). Used for conditions like sleep apnea or less severe respiratory issues.

Ventilator Settings

• Tidal Volume (Vt): The volume of air delivered with each breath. (Usually 6–8 mL/kg of ideal body weight).
• Respiratory Rate (RR): The number of breaths delivered per minute. The normal rate is typically set between 12 to 20 breaths per minute, depending on the patient’s condition.
• Positive End-Expiratory Pressure (PEEP): The pressure in the lungs at the end of expiration. It prevents alveolar collapse and improves oxygenation. Common settings range from 5 to 15 cmH₂O.
• Fraction of Inspired Oxygen (FiO₂): The percentage of oxygen in the air mixture delivered to the patient. It is set to maintain adequate oxygen saturation (usually >90%). It ranges from 21% (room air) to 100%.
• Inspiratory:Expiratory Ratio (I:E ratio): This controls the duration of inspiration relative to expiration. A typical ratio is 1:2, meaning expiration lasts twice as long as inspiration.
• Pressure Control or Volume Control:
  • Pressure Control: The ventilator delivers air until a set pressure is reached.
  • Volume Control: The ventilator delivers a set volume of air with each breath.

Types of Ventilator Modes

• Assist-Control Ventilation (AC): The ventilator delivers a preset number of breaths, but the patient can also initiate additional breaths that will be fully supported by the ventilator.
• Synchronized Intermittent Mandatory Ventilation (SIMV): The ventilator delivers a preset number of breaths, but the patient can take spontaneous breaths in between, without full ventilator assistance.
• Pressure Support Ventilation (PSV): The patient initiates all breaths, and the ventilator provides pressure support for each breath to reduce the work of breathing.
• Continuous Positive Airway Pressure (CPAP): Used in non-invasive settings to maintain positive pressure in the airways, aiding spontaneous breathing.

Monitoring and Care for Intubated Patients

Regular Monitoring

• Oxygen Saturation (SpO₂): Ensure adequate oxygenation levels (usually above 90%).
• Blood Gas Analysis: Monitor arterial blood gases (ABG) to assess oxygen and carbon dioxide levels.
• Ventilator Alarms: Respond to alarms indicating problems like disconnection, high pressure, or patient distress.

Sedation and Comfort

Sedation is often required to keep the patient comfortable and prevent agitation. Common agents include propofol, midazolam, or dexmedetomidine.

Prevention of Complications

• Ventilator-Associated Pneumonia (VAP): Elevating the head of the bed, oral care, and reducing the duration of intubation can help prevent infection.
• Pressure Injuries: Secure the tube properly and rotate the position regularly to avoid injury to the mouth or lips.

Suctioning

Regular suctioning of the airway is necessary to remove secretions and prevent blockage of the endotracheal tube.

Weaning from Mechanical Ventilation

Criteria for Weaning

• Improved respiratory function and resolution of the underlying cause.
• Adequate oxygenation (FiO₂ <40% and PEEP <5-8 cmH₂O).
• Stable cardiovascular function.
• The patient is awake and able to initiate spontaneous breaths.

Weaning Process

1. Spontaneous Breathing Trials (SBT): The ventilator is set to minimal support, and the patient’s ability to breathe independently is tested.
2. Pressure Support Mode: Reduces the ventilator’s support, encouraging the patient to work harder to breathe.
3. Extubation: Once the patient successfully passes the weaning trials, the endotracheal tube is removed. Careful monitoring is needed to ensure the patient can maintain adequate breathing post-extubation.

Complications of Intubation and Mechanical Ventilation

• Barotrauma: Damage to the lung tissue from high pressures used in ventilation, leading to pneumothorax (collapsed lung).
• Ventilator-Associated Pneumonia (VAP): A common infection occurring in patients on long-term mechanical ventilation.
• Tracheal Injury: Injury to the trachea from prolonged intubation or tube movement.
• Airway Obstruction: Mucous plugs or secretions can block the airway, requiring suction or reintubation.

Conclusion

Intubation and mechanical ventilation are critical interventions used to support patients with respiratory failure or compromised airway function. Proper technique, monitoring, and care during the process help to minimize complications and ensure a successful outcome. Understanding the procedures and ventilator settings allows for better management of patients requiring life-support ventilation.