Mechanical Ventilation & Weaning Quiz

Mechanical Ventilation & Weaning

• Mechanical ventilation is a supportive therapy for patients who cannot adequately oxygenate or eliminate carbon dioxide. These patients often have acute respiratory failure.
• A ventilator does not cure the underlying disorder, but supports breathing while the disease is treated.
• A ventilator is a machine that delivers and controls gas flow to a patient. Mechanical ventilation uses a ventilator to facilitate oxygen and carbon dioxide transport between the atmosphere and lungs. This can be done with either negative or positive pressure.

Objectives

• Understand the purposes of mechanical ventilation
• Know the indications for starting mechanical ventilation
• Identify criteria for ventilator support
• Classify positive-pressure ventilators
• Differentiate between ventilator settings, parameters, and controls
• Recognize the different modes of mechanical ventilation
• Explain weaning methods
• Know the criteria for weaning
• Identify the nurse's role in weaning

Outlines

• Introduction to mechanical ventilation
• Purposes of mechanical ventilation
• Indications for mechanical ventilation
• Criteria for initiating ventilator support
• Types of ventilators
• Ventilator modes
• Ventilator settings
• Ventilator alarms
• Complications of mechanical ventilation
• Weaning from mechanical ventilation
• Nursing role in weaning

Introduction to Mechanical Ventilation

• Mechanical ventilation helps patients who cannot maintain adequate oxygenation or carbon dioxide elimination, often due to acute respiratory failure.

Definition

• A ventilator delivers and controls gas flow to a patient. Mechanical ventilation uses a ventilator to facilitate oxygen and carbon dioxide transport between the atmosphere and lungs. This can be done with either negative or positive pressure.

Purposes of Mechanical Ventilation

• Support the pulmonary system until the cause of failure is corrected
• Provide appropriate oxygen supplementation
• Reduce the work of breathing
• Improve patient comfort during respiration

Indications for Mechanical Ventilation (Ventilation Abnormalities)

• Respiratory muscle dysfunction (muscle fatigue)
• Neuromuscular disease (e.g., Guillain-Barré syndrome)
• Decreased ventilatory drive (e.g., cardiopulmonary arrest)
• Increased airway resistance or obstruction (e.g., chronic obstructive pulmonary disease (COPD))

Indications for Mechanical Ventilation (Oxygenation Abnormalities)

• Severe hypoxemia (acute hypoxemic respiratory failure)
• Obstructive lung disease (e.g., asthma)
• Restricted lung disease (e.g., pulmonary edema)
• Paralyzed patients (e.g., general anesthesia)

Criteria for Initiation of Ventilator Support

Types of Mechanical Ventilation

• Negative pressure: External vent that doesn't require intubation. Creates negative pressure on the chest to allow air into the lungs. Example: Iron lung.
• Positive pressure: Non-invasive techniques that don´t require intubation. Provides ventilation via a mouthpiece with a tight seal. Invasive techniques use a bedside machine requiring intubation with an artificial airway (like an endotracheal tube) to force positive pressure on the chest.

Positive Pressure Ventilators Settings

• Fraction of inspired oxygen (FiO2): The concentration of oxygen in the gas used for ventilation, ranging from 0.21 (room air) to 1.0 (100%).
• Tidal volume (Vt): The volume of air with each breath, measured in milliliters and typically set between 6 and 10 mL/kg.
• Respiratory rate (RR) or frequency (f): The number of breaths per minute the ventilator delivers, usually between 10 and 20 breaths/minute.
• Inspiratory (I) and expiratory (E) time (I/E ratio): The ratio of inspiratory time to expiratory time; usually 1:1.5 or 1:2.
• Flow rate: The speed at which tidal volume is delivered; typically 40-100 liters per minute.
• Sensitivity/Trigger: The amount of effort the patient needs to initiate a breath.
• Sigh: A deep breath with a greater volume than tidal volume.

Types of Positive Pressure Ventilators

• Volume-cycled: Delivers air until a preset tidal volume is reached.
• Pressure-cycled: Delivers air until a preset pressure is reached.
• Time-cycled: Delivers air for a preset amount of time.

Ventilator Modes

• Control Mandatory Ventilation (CMV): Complete ventilation provided by the ventilator; the patient has no interaction with the ventilator, but sedation/neuromuscular blockade may be needed.
• Assist-Control Ventilation (AC): Patient-initiated breaths receive a preset tidal volume. Preset tidal volume and minimum ventilator rate; sedation to limit breaths may be required.
• Synchronized Intermittent Mandatory Ventilation (SIMV): Preset tidal volume with minimum rate; patients take additional spontaneous breaths at their tidal volume/rate. Often used with pressure support.
• Pressure Support Ventilation (PSV): Positive support pressure assist during spontaneous inspiration. Pressure controlled, patient triggered, pressure limited, and patient cycled.
• Continuous Positive Airway Pressure (CPAP): No machine breaths, but allows spontaneous breathing at an elevated baseline pressure. Patient controls rate and tidal volume. Used to assess and strengthen breathing prior to extubation.
• Positive End Expiratory Pressure (PEEP): Positive pressure applied by the ventilator at the end of exhalation to improve oxygenation (by opening collapsed alveoli).

Mechanical Ventilator Alarms

• High pressure/volume: Increased secretions, kinked tubing, patient biting/coughing, water in tubing, ETT advanced into right main-stem bronchus. Interventions: Suction, unkink tube, check for lung sounds, place oral airway, drain water, ensure proper ETT placement, notify physician.
• Low pressure/volume: Disconnected tubing, ETT cuff leak, hole in tubing, humidifier leak. Interventions: Secure connections, deflate/re-inflate cuff, recheck cuff pressure, change tube, tighten humidifier, notify physician.
• High Respiratory rate: Patient anxiety, pain, hypoxia, fever. Interventions: Reassure patient, pain/fever control.
• Apnea: No spontaneous breaths taken. Interventions: Encourage breathing, adjust ventilator mode, notify physician.
• Oxygen alarm: Insufficient/disconnected O2 supply. Interventions: Notify staff to correct malfunction, manually ventilate, monitor oxygen saturation.

Complications of Positive Pressure Ventilation

• Pulmonary system: Barotrauma, acid-base disturbance, Ventilator-Associated Pneumonia (VAP), aspiration, pulmonary infections, oxygen toxicity, ventilator dependence/inability to wean.
• Other systems: Decreased cardiac output (CO), hypotension, sodium and water retention, increased intracranial pressure (ICP), stress ulcers/GI bleeding, immobility-related complications (muscle contractures, pressure ulcers, deep vein thrombosis (DVT)), pain, fear, agitation, and anxiety.

VAP Bundle

• Semi-recumbent positioning with head elevation (30-45 degrees).
• Sedation vacation
• Continuous subglottic secretion removal
• Oral vs. nasal feeding tubes (aspiration prevention)
• Oral hygiene with chlorohexidine
• Stress ulcer prophylaxis

Weaning from Mechanical Ventilation

• Weaning is transferring a patient from ventilator support to spontaneous breathing.

Methods of Weaning

• Synchronized intermittent mandatory ventilation (SIMV) weaning
• Continuous positive airway pressure (CPAP) weaning
• Pressure support ventilation (PSV) weaning
• T-Piece trial

Weaning Criteria

• Awake and alert
• Hemodynamically stable (not needing vasoactive support)
• Arterial blood gases (ABGs) normalized (PaO2 > 60 mmHg on FiO2 < 50%, PaCO2 acceptable with pH of 7.35-7.45)
• Lung mechanics: PEEP ≤ 5 cm H₂O
• Chest X-ray reviewed for correctable factors; treated as needed
• General parameters: Core temperature (36°C to 39°C), adequate pain/anxiety/agitation management, no residual neuromuscular blockade

Nursing Role Before Weaning

• Assess readiness for weaning
• Wean only during the day
• Explain the process of weaning to the patient
• Offer reassurance to the patient
• Elevate the head of the bed and position the patient upright.
• Ensure a patent airway and suction as needed.
• Monitor the patient's response (use of accessory muscles, ABGs & O2 saturation, spontaneous respiratory rate).
• Record the data of weaning trial

Nursing Role During Weaning

• Remain with the patient during weaning initiation
• Instruct the patient to relax and breathe normally
• Monitor respiratory rate, vital signs, ABGs, diaphoresis, and use of accessory muscles frequently.
• Discontinue weaning trials if fatigue or respiratory distress develops.
• Monitor patients for: Dysrhythmias, increase or decrease in heart rate (>20 beats/min), increase or decrease in blood pressure (>20 mmHg), increase in respiratory rate (>10 above baseline or >30), signs of weaning intolerance (tidal volumes < 250mL, diaphoresis, decreased level of consciousness (LOC), dyspnea, restlessness, SaO2 < 90%, PaO2 < 60 mmHg)

Nursing Role After Weaning

• Ensure that extubation criteria are met
• Decanulate (remove the endotracheal tube) the patient
• Document all patient parameters and response.

Care of the Ventilated Patient

• Assess patient status and functioning of ventilator.
• Promote optimal gas exchange.
• Reduce mucus accumulation.
• Prevent trauma.
• Prevent infection.
• Obtain optimal mobility.
• Establish non-verbal communication.

Test your knowledge on mechanical ventilation and weaning processes. This quiz covers the purposes, indications, and classifications of mechanical ventilation, along with the criteria for initiating and stopping support. Challenge yourself on the various modes and settings of ventilators.