Ventilator Support

Objectives of the Course

The objectives as presented include:

  1. Identify the criteria used to determine the need for mechanical ventilator support.

  2. Describe the modes of mechanical ventilation.

  3. Explain the commonly monitored ventilator settings.

  4. Discuss the major complications of mechanical ventilation with intubation.

  5. Briefly explain noninvasive ventilator support.

  6. Describe the nursing care of the patient requiring ventilator support.

  7. Describe the process of weaning a patient from mechanical ventilation and the nurse's role in the process.

Types of Ventilatory Support

  1. Noninvasive Ventilatory Support: Examples include BiPAP (Bi-level Positive Airway Pressure) or CPAP (Continuous Positive Airway Pressure).

  2. Invasive Ventilation Support: This includes mechanical ventilation via an endotracheal tube (ET), which can be nasotracheal or orotracheal.

Modes of Noninvasive Ventilatory Support

  • BiPAP (Bi-level Positive Airway Pressure):

    • Higher pressures are delivered during inspiration, referred to as Inspiratory Positive Airway Pressure (IPAP).

    • Lower pressures are delivered during exhalation.

  • CPAP (Continuous Positive Airway Pressure):

    • Maintains the same pressure throughout the entire respiratory cycle, without pressure reduction during exhalation.

    • It functions similarly to Positive End Expiratory Pressure (PEEP), which is used for a client on a ventilator.

Comparison between CPAP and BiPAP

  • CPAP:

    • Continuous air pressure of up to 20 cmH2O during inhalation.

    • No significant pressure reduction during exhalation.

  • BiPAP:

    • Continuous air pressure can go up to 25 cmH2O during inhalation.

    • Allows for a pressure reduction of up to 90% during exhalation.

Ventilatory Support: Indications and Contraindications

BiPAP Indications:

  • Acute Respiratory Failure

  • COPD (Chronic Obstructive Pulmonary Disease)

  • Patients with Heart Failure

  • Weak Respiratory Muscles

  • Altered Mental Status

  • Increased Secretions

Contraindications:

  • Intact gag reflex and ability to protect own airway.

  • DNR or DNI code level.

  • Massive airway trauma.

  • Non-passable upper airway obstruction, requiring cricothyroidotomy or emergency tracheostomy.

Intubation with Mechanical Ventilation

Endotracheal Tube Components:

  • Tube cuff, 15-mm connector to the oxygen source.

  • Cuff inflation line and pilot balloon.

  • Spring-loaded cuff inflation valve.

Complications Associated with Endotracheal Intubation:

  1. Limited head and neck motion due to arthritis or cervical spine injury.

  2. Potential for teeth to be chipped or removed, causing airway obstruction.

  3. Risk of client obstructing by biting the tube.

  4. Increased salivation and difficulty swallowing, leading to challenging mouth care.

The 6 P’s of Intubation:

  1. Preparation: Obtain consent and set up equipment. Prepare medications for Rapid Sequence Intubation (RSI).

  2. Preoxygenation: Use 100% oxygen with a bag valve mask (BVM).

  3. Pretreatment: Administer medications to reduce adverse effects of intubation.

  4. Paralysis and induction: Administer medications for airway control.

  5. Placement: Verify tube placement by auscultation for lung sounds and visual checks.

Rapid Sequence Intubation Medications

  • Pretreatment Medications:

    • Lidocaine (1.5 mg/kg): Reduces risk of increased intracranial pressure (ICP).

    • Fentanyl (3 mcg/kg): Damps sympathetic nervous response to intubation.

  • Induction Medications:

    • Etomidate (0.3 mg/kg): Provides anesthesia, contraindicated in cases of adrenal insufficiency.

    • Ketamine (1-2 mg/kg): Provides anesthesia by inhibiting neuroexcitation.

    • Midazolam (0.2 mg/kg): Sedative and amnesic, cautioned in hypotensive/hypovolemic patients.

    • Propofol (1.5-3 mg/kg): Suppresses brain activity; causes vasodilation.

  • Paralysis (Neuromuscular Blockade):

    • Succinylcholine (1.5 mg/kg): First choice unless contraindicated, lasts 4-10 minutes, may cause bradycardia and hypotension.

    • Rocuronium (1 mg/kg): Second choice for paralysis, lasts about 45 minutes.

    • Vecuronium (0.15 mg/kg): Alternative to Rocuronium, lasts 25-40 minutes.

Nursing Priorities of Care for Endotracheal Tube

Monitoring:

  1. Correct positioning of the tube: Document position at the teeth or lip.

  2. Careful observation for symmetric chest rise and fall, lung auscultation (unilateral breath sounds may indicate tube misplacement).

  3. Measure and document cuff pressure (20-25 cmH2O); use MOV (Minimal Occlusive Volume) or MLT (Mean Leak Test) technique.

  4. Monitor for signs of unplanned extubation or airway complications such as aspiration.

Maintenance:

  • Maintain proper cuff inflation; replace suction equipment every 24 hours.

  • Provide oral care every 2-4 hours, clean mouth with suction toothbrush or chlorhexidine.

  • Frequent assessment of skin integrity around the tube and repositioning if necessary.

Comfort and Communication:

  • Assure pain control: Use both pharmacological and non-pharmacological techniques.

  • Facilitate communication through alternative means (e.g., white boards, notepads).

Complications Assessment:

  • Monitor for major issues such as unplanned extubation and aspiration, providing immediate support and maintaining the airway if these occur.

Positive Pressure Ventilation (PPV)

  • Positive pressure ventilation involves the ventilator forcing air into the airway under positive pressure, thus increasing intrathoracic pressure to inflate the lungs while exhalation remains passive.

Methods of Ventilation by Ventilators:

  1. Volume Controlled Breathing: Delivers a set tidal volume with each breath; pressure within the lungs varies with compliance. Increased risk of volutrauma exists due to possible overdistension or rupture of alveoli.

  2. Pressure Controlled Breathing: Delivers a set amount of pressure for air delivery, while the volume delivered varies based on compliance of the lungs.

Common Modes of Mechanical Ventilation

  • Assist-Control Ventilation (A/C): Every triggered breath (by patient or ventilator) is fully controlled, delivering a set volume or pressure.

  • Synchronized Intermittent Mandatory Ventilation (SIMV): Delivers a set number of breaths with full support while allowing the patient to breathe independently with minimal pressure support.

  • Pressure Support Ventilation (PS): The patient breathes entirely on their own with added pressure support from the ventilator.

Other Methods of Oxygenation and Ventilation

  1. High Frequency Oscillatory Ventilation (HFOV)

  2. Nitric Oxide (NO)

  3. Prone Positioning

  4. Extracorporeal Membrane Oxygenation (ECMO)

Complications of Positive Pressure Ventilation

Major Complications:

  1. Barotrauma: Excess pressure distends the thoracic cavity causing rupture of alveoli.

  2. Volutrauma: Excessive volumes lead to rupture risks.

  3. Alveolar hypoventilation: Resulting from air leaks or inadequate tidal volumes, potentially causing atelectasis.

  4. Alveolar hyperventilation: Caused by excessive volumes leading to overdistension.

  5. Ventilator-Associated Pneumonia (VAP): Pneumonia that develops after 48 hours of mechanical ventilation due to various risk factors.

VAP Prevention Strategies:

  • Minimize sedation and encourage early mobilization of the patient.

  • Maintain head elevation at least 30 degrees.

  • Conduct oral care with chlorhexidine.

  • Ensure strict hand hygiene during suctioning and contact with the patient.

Ventilator Alarms

  1. Low-pressure alarm: Indicates lack of resistance, possibly due to disconnect or cuff leak.

  2. High-pressure alarm: Suggests excessive resistance, possibly due to secretions or tube kinking.

  3. Apnea alarm: Notifies if spontaneous breathing ceases.

    • In case of an undetermined alarm cause, disconnect and use manual ventilation with an Ambu bag.

Complications of Positive Pressure Ventilation: Psychosocial Implications

  • Patients often experience significant discomfort, anxiety, and pain due to immobility and reliance on invasive equipment.

Sedation and Analgesia during Mechanical Ventilation

  • Medically ventilated patients often require sedation (e.g., propofol) and analgesia (e.g., fentanyl). Neuromuscular blockade may also be necessary to prevent patient-ventilator dyssynchrony, assessed through a Train of Four test.

Neurological Complications

  • Increased thoracic pressures can decrease venous return from the brain, resulting in increased ICP. Elevating the head of the bed to 30-45 degrees can help prevent this.

Sodium/Water Balance Issues

  • Fluid retention may ensue after 48-72 hours of PPV, attributed to various physiological responses, affecting treatment and recovery.

Gastrointestinal Complications

  • Stress from illness may lead to increased gastric acid secretion. Prevention methods include using proton pump inhibitors (e.g., pantoprazole) and monitoring for bowel dilation due to air or gas accumulation.

Musculoskeletal Complications

  • Atrophy resulting from immobility necessitates early consultation with physical and occupational therapies and implementing range-of-motion exercises.

Nutritional Considerations during Mechanical Ventilation

  • The metabolic demands of mechanically ventilated patients may contribute to inadequate nutrition, delaying the weaning process. Nutritional programs should be initiated if expectant fasting exceeds 3-5 days.

Weaning from Mechanical Ventilation

Readiness Indicators:

  • Resolution of underlying disease processes.

  • Adequate oxygenation levels must be achieved (PaO2/FiO2 ratio >150, SpO2>90%, PEEP <5 cmH2O, FiO2 <40-60%, pH > 7.25).

  • Hemodynamically stable without myocardial ischemia or blood pressure issues.

  • Patient's respiratory drive should be intact; they need to be able to initiate their own breaths.

Optional Criteria:

  • Hemoglobin levels >7, core temperature <100.4F, and mental status returning to baseline.

Weaning Procedure:

  • The weaning process involves gradually reducing ventilatory support until the patient can breathe spontaneously, incorporating spontaneous breathing trials (SBTs).

  • Pre-weaning assessment involves evaluating the patient's capacity for independent breathing, decreasing sedation to enable spontaneous awakening trials (SATs) and careful monitoring for signs of distress.

Extubation Procedure:

  • Hyperoxygenate and suction prior to extubation.

  • Carefully loosen straps or tapes of the ET tube.

  • Instruct the patient to take a deep breath, deflate the cuff, and remove the tube at the peak of inhalation.

  • Follow up with assessing vital signs and respiratory status immediately after, as per protocol.

Questions for Discussion

  • An invitation for questions or discussions regarding the material presented has been offered to encourage further clarification on the outlined topics.