Mechanical Ventilation Lecture

Introduction

• Mechanical ventilation: Life-saving intervention for patients unable to breathe on their own.
• Uses positive pressure: Delivers oxygenated air into the lungs for gas exchange.
• Complex topic: Important for respiratory therapists and medical professionals to understand.

Indications for Mechanical Ventilation

• Insufficient oxygenation: When not enough oxygen is received, impacting tissues and organs.
• Insufficient ventilation: When carbon dioxide is not removed, leading to increased blood acidity.
• Acute lung injury: From events like sepsis, pneumonia, aspiration, or severe asthma.
• Severe hypotension: Conditions like shock, sepsis, CHF causing extremely low blood pressure.
• Inability to protect the airway: Risk of aspirating secretions into the lungs.
• Upper airway obstruction: Conditions like epiglottitis and laryngeal edema.
• General indication: Whenever spontaneous breathing is inadequate to sustain life.

Contraindications

• No true contraindications as patients cannot survive without adequate ventilation and oxygenation.
• Patient choice: Some patients may choose not to receive mechanical ventilation (e.g., DNR orders).

Principles of Mechanical Ventilation

• Ventilation: Moving air into and out of the lungs.
• Oxygenation: Absorbing oxygen into the bloodstream.
• Lung compliance: Lung's ability to expand and contract.
• Airway resistance: Impedance of airflow through the respiratory tract.
• Dead space ventilation: Volume of ventilated air that doesn't participate in gas exchange.
• Respiratory failure: Inability of the lungs to oxygenate blood or remove carbon dioxide.

Mechanical Ventilator

• Breathing machine: Uses positive pressure to deliver breaths.
• Intubation required: Artificial airway (endotracheal tube) connects the patient to the ventilator.
• Supportive device: Assists with breathing until the patient's condition is treated.

Benefits

• Decreases work of breathing: Reduces energy and work for each breath.
• Maintains adequate oxygenation: Can deliver up to 100% FiO2 and Positive End-Expiratory Pressure (PEEP).
• Helps remove CO2: Increased respiratory rate or tidal volume helps with CO2 removal.
• Provides stability: Supports the patient allowing other treatments to work.

Complications

• Barot trauma: Injury from alveolar over-distention.
• Ventilator-associated pneumonia: Develops after 48+ hours of ventilation.
• Positive End Expiratory Pressure (PEEP) complications.
• Oxygen toxicity: Cell damage from high oxygen levels over time.
• Ventilator-induced lung injury.

Types of Mechanical Ventilation

1. Positive pressure: Common type, uses higher pressure to push air into lungs.
2. Negative pressure: Less common, uses lower pressure outside thoracic cavity.
   • Examples: Iron lung, cuirass ventilation.
3. Invasive: Involves artificial airways (endotracheal tubes or tracheostomy tubes).
4. Non-invasive: Uses face masks (CPAP and BiPAP).

Ventilator Modes

• Volume control: Delivered volume set by operator, variable Peak Inspiratory Pressure.
• Pressure control: Delivered pressure set by operator, variable tidal volume.
• Primary modes: Assist-control (full support) and SIMV (partial support).

Ventilator Settings

• Mode: Determines how the ventilator functions.
• Tidal volume: Volume of air delivered per breath.
• Frequency/rate: Number of breaths per minute.
• FiO2: Percentage of inspired oxygen.
• Flow rate: Rate of air delivery.
• I:E ratio: Ratio of inspiratory to expiratory times.
• Sensitivity: Effort needed to trigger a breath.
• PEEP: Pressure to keep alveoli open at end of exhalation.
• Alarms: Safety mechanisms for detecting issues.

Initiation of Mechanical Ventilation

• Initial settings: Mode, tidal volume, frequency, FiO2, flow rate, I:E ratio, sensitivity, PEEP.
• Tailored to the patient's condition and adjusted over time.

Artificial Airways

• Endotracheal tubes (ET tubes): Through nose/mouth into trachea.
• Tracheostomy tubes: Through neck incision directly into trachea.
• Other types: Oropharyngeal, nasopharyngeal, LMA, King laryngeal tubes, esophageal obturator airways, etc.

Drugs Used

• Sedatives: Calming, relaxing, reducing anxiety (e.g., benzodiazepines).
• Analgesics: Pain relief (e.g., morphine, fentanyl).
• Paralytics: Muscle relaxation (e.g., neuromuscular blocking agents).

Ventilator Management and Monitoring

• Ventilator management: Assess oxygenation/ventilation, adjust settings, manage airway, provide humidification.
• Monitoring: Vital signs, breath sounds, imaging, blood gases, capnography.

Ventilator Alarms

• Types of alarms: High pressure, low pressure, low volume, high frequency, apnea, high PEEP, low PEEP.

Ventilator Waveforms

• Types of waveforms: Flow-volume loop, pressure-volume loop, constant flow, descending ramp, pressure-time, flow-time.
• Used to assess lung mechanics and ventilator settings.

Ventilator Troubleshooting

• Common problems: Bronchospasm, secretion buildup, airway obstruction, Dynamic hyperinflation, kinked tube, patient positioning, etc.

Weaning from Mechanical Ventilation

• Process: Gradually reducing support to allow spontaneous breathing.
• Success factors: Type of disease, patient age, comorbidities, duration on ventilator.
• Weaning criteria: Stable condition, adequate cough, manageable secretions, stable oxygenation and hemodynamics.

Extubation

• Factors: Ability to protect the airway, maintain respiratory function, manage secretions, stable hemodynamics.
• Procedures: Typically performed by respiratory therapists.

Neonatal Mechanical Ventilation

• Special considerations: Smaller tidal volumes and lower pressure needs.
• Anatomical differences require specific ventilatory support.

Conclusion

• Importance of understanding: Crucial for respiratory therapists and medical professionals.
• Complex topic: Requires thorough knowledge and understanding.

Further Learning Resources

• Guide on website: More detailed information available online.
• Additional videos: Other helpful videos linked for further learning and support.