Introduction
Ventilator modes are tailored to a Patients weight, lung mechanics, and clinical condition. These modes determine how breaths are delivered—either fully controlled by the ventilator or shared with the patient.
Definition
Mechanical ventilation is the process by which a machine (mechanical ventilator) directly supplies 21% of fraction of inspired oxygen (FiO2) into the airways of the patient through an ET tube or tracheostomy.
Purposes
- To provide relief from respiratory distress.
- To improve gas exchange.
- To reduce the effort of breathing.
- To reverse fatigue in respiratory muscles.
- To enhance healing especially after lung surgery.
- To prevent complications.
Indications
- Apnea, for example, neuromuscular or cardiopulmonary collapse.
- Respiratory failure.
- Compromised airway.
- Severe hypoxemia.
- Respiratory muscle fatigue.
- Chronic obstructive pulmonary diseases.
- Brain herniation.
- Cyclic antidepressant toxicity.
- Persistent acidosis.
- Thoracic and abdominal surgery.
- Drug overdose.
- Inhalation injury.
- Neuromuscular disorders.
- Multiple trauma.
- Shock.
- Multiple system failure.
- Coma/unconsciousness.
- Abnormal ABG values.
- PaO2 <50 mmHg with FiO2 >60%.
- PaCO2 >50 mmHg with pH ≤7.25 or ≥7.45.
- Vital capacity <2 times tidal volume.
- Respiratory rate >35 breaths/min.
- Apneic spells.
Contraindications
- Severe dysrhythmias.
- Cognitive impairment.
- Head or facial trauma.
Types
1) Negative-Pressure Ventilators
In this type, negative pressure is exerted on the external chest. The decrease in intrathoracic pressure during inspiration results in inflow of air into the lungs, for example, iron lung, body wrap, and chest cuirass.
2) Positive-Pressure Ventilators
Here, lung inflation occurs by positive pressure which is exerted on the airway. The various subtypes are discussed next.
- Pressure Cycled
The air is delivered until the preset pressure is reached and then it cycles off. Expiration occurs passively. - Time Cycled
The inspiration is terminated after a preset time. The volume depends on the length of inspiration and flow rate of air. - Volume Cycled
The volume of air delivered with each inspiration is preset. When the preset volume is delivered, exhalation occurs passively. - Noninvasive Positive-Pressure Ventilators
The various subtypes are as follows: - Continuous positive airway pressure (CPAP).
- Bilevel positive airway pressure (BiPAP).
Modes of Mechanical Ventilation
Two kinds of modes are discussed next:
- Modes of volume ventilation.
- Modes of pressure ventilation.
| Various Modes of Mechanical Ventilation. | |
| Modes of Volume Ventilation | Modes of Pressure Ventilation |
| Control mandatory ventilation (CMV) or control ventilation (CV). Assist control ventilation or assisted mandatory ventilation (AMV). Synchronized intermittent mandatory ventilation (SIMV). Intermittent mandatory ventilation (IMV). | Pressure support ventilation (PSV). Pressure-controlled inverse ratio ventilation (PCIRV). Positive end-expiratory pressure (PEEP). |
Settings of Mechanical Ventilation
| Parameter | Settings |
| Respiratory rate | 6-20 breaths/min. |
| Tidal volume | Usual volume is 10-12 mL/kg. In case of lung injury, it should be 6-8 mL/kg. |
| Oxygen concentration | Usually adjusted to maintain PaO2 level >80 mmHg or SpO2level >90%. |
| PEEP | Usually, 3-5 cm H₂O. PEEP > 10 cm can cause alveolar distension. |
| Inspiratory to expiratory ratio | Duration of inspiration to duration of expiration is normally maintained at 1:2 to 1:1.5. |
| Inspiratory flow rate and time | Speed with which the tidal volume is delivered. Normally, 40-80 L/min at 0.8-1.2 seconds is maintained. |
| Sensitivity | or a pressure trigger is 0.5-1.5 cm H₂O and for a flow trigger is 1-3 L/min below baseline flow. |
| High-pressure limit | or a pressure trigger is 0.5-1.5 cm H₂O and for a flow trigger is 1-3 L/min below baseline flow. |
Articles:
| Articles | Purpose | |
| 1. | Crash cart with emergency medication. | To sedate and resuscitate the patient. |
| 2. | ET intubation trolley. | Facilitates ET intubation. |
| 3. | Suction apparatus with equipment (based on closed or open method of suctioning). | Facilitates suctioning during mechanical ventilation. |
| 4. | Pulse oximeter. | To assess the saturation of oxygen. |
| 5. | Resuscitation equipment (Ambu bag with appropriate size of mask) with advanced respiratory equipment such as laryngeal mask and Combitube. | Revives the patient’s condition during the procedure. |
| 6. | Cardiac monitor. | Identifies the vital parameters such as temperature, pulse rate, respiratory rate, and blood pressure. |
| 7. | Oxygen source. | To support the patient with oxygen. |
| 8. | Stethoscope. | To auscultate the lungs and heart sounds. |
| 8. | Humidification system. | To supply humidified ventilation. |
| 9. | Flow chart. | To document the condition of the patient with mechanical ventilator. |
| 10. | Personal protective equipment (PPE) such as mask, gloves, caps. | To maintain aseptic techniques during procedure. |
Procedure
| Nursing action | Rationale | |
| 1. | Obtain baseline ABG value and chest X-ray. | Helps to determine progress of therapy. |
| 2. | Explain the procedure to the patient and family. | Enhances cooperation. |
| 3. | Administer premedication as per the physician’s order. | Enhance cooperation through mild sedation. |
| 4. | Establish the airway by tracheostomy or cuffed ET tube. | A closed system is necessary for positive-pressure ventilation. |
| 5. | Prepare the ventilator. Turn on power. Set Tidal volume (V) (usually 5-7 mL/kg body weight). Peak pressure. Fractionated oxygen level. Ventilator sensitivity. Rate at 12-14breaths/min. Flow rate. Inspiratory to expiratory ratio (I: E). | Prior preparation saves time and energy. These settings can be adjusted and changed according to the patient’s demand. |
| 6. | Connect oxygen and compressed air source. | To promote oxygenation. |
| 7. | Select mode of ventilator-controlled, assist control, SIMV, PEEP, CPAP, or PSV. | Mode is selected according to the patient’s condition. |
| 8. | Check machine functional measures, V., rate, and IE ratio; analyze oxygen: check all the alarms. | Mode is selected according to the patient’s condition. |
| 9. | Based on the patient’s condition and ABG value, set the ranges for alarm. High-pressure alarm limits: 10-15 cm H₂O. Low pressure alarm: 5-10 cm H₂O. | To identify changes and to act. High-pressure alarm indicates decreased lung compliance (pulmonary disease), decreased lung volume (pneumothorax, tension pneumothorax, haemothorax, pleural effusion), increased airway resistance (secretions, coughing, bronchospasm), and loss of patency of airway (mucus plug, airway spasm, biting or kinking of the tube). Low-pressure alarm indicates disconnection, leak, changing compliance, and resistance. |
| 10. | Connect the patient to the ventilator. | To support the patient. |
| 11. | Assess for adequate chest movement and rate. | Ensures proper functioning of the equipment. |
| 12. | Assess frequently for change in respiratory status by ABG, pulse oximetry, respiratory rate, use of accessory muscles, breath sounds, and vital signs. | To identify the changes and to change the settings accordingly. |
| 13. | Monitor and troubleshoot alarm conditions. Ensure appropriate ventilation at all times. | To identify and correct problems. |
| 14. | Change position every 2 hours (Q2H). Lateral position is desirable, from right semi prone to left semi prone. Make the patient to sit in upright position at regular intervals if possible. | To prevent pressure ulcers. |
| 15. | Assess the need for suctioning at least every 2 hours (closed suction is ideal than intermittent suction). | To clear secretions. Intermittent suctioning increases the risk of ventilator-associated pneumonia (VAP). |
| 16. | Auscultate breath sounds every 2 hours and observe for diaphragmatic excursions and use of accessory muscles of respiration. | To identify the accumulation of secretions, air entry, and any difficulty in breathing. |
| 17. | Check the water level in the humidifier. | To ensure that humidification is adequate. |
| 18. | Always wash hands after emptying Prevents cross-contamination fluid from the ventilator circuit | Monitor for change in compliance or onset of conditions that may cause airway pressure to increase or decrease. |
| 19. | Assess airway pressure at frequent intervals. | Monitor for change in compliance or onset of conditions that may cause airway pressure to increase or decrease. |
| 20. | Measure delivered tidal volume and analyze oxygen concentration every 4 hours or more frequently if indicated. | Monitor for change in compliance or onset of conditions that may cause airway pressure to increase or decrease. To ensure that the patient is receiving the appropriate ventilator assistance. |
| ET care | ||
| 21. | Apply suctioning every 4 hours or whenever necessary. Inflation of ET/ tracheostomy tube cuffs to be monitored regularly. Rotate the ET tube daily to prevent pressure ulcer on the patient’s lips and tongue. Humidifier to be changed daily and kept adequately filled with sterile distilled water. | Prevents obstruction of the ET tube and VAP. |
| 22. | Monitor for cardiovascular function. Assess for arborealities. Monitor pulse rate and arterial BP; intra-arterial BP monitoring may be carried out. | To assess the cardiovascular status. |
| 23. | Monitor pulmonary capillary wedge pressure, mixed venous oxygen saturation (SVO), and cardiac output. | Intermittent and continuous positive-pressure ventilation may increase the pulmonary artery pressure and decrease the cardiac output. |
| 24. | Monitor for pulmonary infection. Aspirate tracheal secretions into a sterile container and send it to the laboratory for culture and sensitivity testing. | Allows for the earliest detection of infection or change in infecting organisms in the tracheobronchial tree. |
| 25. | Evaluate the need for sedation or muscle relaxants. | Sedatives may be prescribed to decrease anxiety or to relax the patient to prevent competing with the ventilator. |
| 26. | Report intake and output precisely and obtain an accurate daily weight if possible. | To monitor fluid balance. Positive fluid balance results in increase in body weight and interstitial pulmonary edema, and early recognition of fluid accumulation. |
| 27. | Monitor nutritional status. Provide enteral or parenteral nourishment. | To maintain the metabolic needs of the body. |
| 28. | Monitor gastrointestinal function. | Mechanically ventilated patients are at risk for the development of stress ulcers. |
| 29. | Perform passive ROM exercise of all extremities for patients who are unable to do so. | Prevents contractures. |
| 30. | Provide mouth care for every 1-4 hours. Assess the pressure area from ET tubes. | Enhances comfort and reduces the risk of infection. |
| 31. | Test stools and gastric drainage for occult blood. | Stress may lead to gastrointestinal bleeding. |
| 32. | Measure abdominal girth daily. | Provides objective assessment of the degree of distension. |
| 33. | Use alternative methods of communication. Use communication board or booklet to communicate with the patient. | To meet basic needs. |
| 34. | Provide psychological support. Orient to the environment and function of mechanical ventilator. Ensure adequate rest and sleep. | Mechanical ventilation may result in sleep deprivation and loss of touch with surroundings and reality. |
| 35. | Maintain flow sheet to record ventilation pattern, ABGs, venous determinations, and hemoglobin every 1 hour. | Documentation enhances to comply with legal and ethical rules. |
| 36. | Change the ventilator circuit every 24 hours and assess the ventilator function every 4 hours. | Prevents contamination of the lower airways (VAP). |
| 37. | Check the position of the ET tube; measure the cuff pressure daily using manometer. | To keep the airway in position. |
| 38. | Follow measures to prevent. VAP. Adhere “ventilator bundle” protocol according to the hospital’s policy. Peptic ulcer disease prophylaxis. Deep vein thrombosis prophylaxis (unless contraindicated). Catheter-related bloodstream infection (CBSI) protocol. Use catheter-related urinary tract infection (CAUTI) prophylaxis protocol. Elevate the head end of the bed to 30°-45°. Apply closed suctioning. | Infection deteriorates the general condition. |
| Weaning process | ||
| 39. | Preweaning Assess the patient for weaning criteria: vital capacity, 10-15 ml/kg: tidal volume, 7-9 mL/kg, minute ventilation, 6 L/min maximum inspiratory pressure (MIP), 20 cm H₂O: PaO2, greater than 60 mmHg with FiO2, less than 40%, rapid or shallow breathing index-less than 100 breaths/min. Assess the intake and output, nutritional status, activity level, laboratory values, vital signs, and psychological readiness for weaning. | The patient must be physically and psychologically ready for weaning. |
| 40. | Weaning phase | |
| Prepare appropriate equipment. | ||
| Position the patient in sitting or semi-Fowler’s position. | Increases lung compliance and work of breathing. | |
| Preferably early morning is the ideal time for weaning or according to the physician’s order. | The patient should be rested. | |
| Perform bronchial hygiene such as postural drainage and suctioning before weaning. | The patient should be in the best pulmonary condition for weaning to be successful. | |
| Disconnect the mechanical ventilator and connect with the T-piece adapter. | Stay with the patient to monitor for tolerance of the procedure. | |
| Monitor the patient for factors indicating need for reinstitution of mechanical ventilation. | Indicates intolerance to weaning procedure. | |
| Blood pressure increases or decreases greater than 20 mmHg in systolic pressure or 10 mmHg in diastolic pressure. | ||
| Heart rate increases 20 beats/min, greater than 110 beats/min. | ||
| Respiratory rate increases 10 breaths/min or greater than 35 breaths/min. | ||
| Tidal volume less than 250-300 mL (in adults). | ||
| PaO2, less than 60, PaCO2 greater than 55, or pH less than 7.35. | ||
| When the patient tolerates 40-60 minutes of continuous weaning, weaning increments can increase rapidly. | ||
| When the patient tolerates spontaneous ventilation throughout the day, begin night weaning. | ||
| CPAP/IMV/SIMV weaning | ||
| Set the ventilator to CPAP/ IMV/ SIMV mode as applicable. | To aid in the weaning process. | |
| Set the rate level. | Rate is set based on the patient’s condition. | |
| Assess the patient’s tolerance of the procedure. In rapid weaning, changes may be made approximately every 20-30 minutes. | To monitor progress and adapt changes accordingly. | |
| 41. | Postweaning phase Check and record vital signs every hour. | To obtain baseline data. |
| Attend the personal hygiene. Daily bath and change the bed linen. Oral hygiene every 4 hours and whenever needed. Eye care every 4 hours and instill artificial tears and cover the eyes with the gauze to prevent exposure keratitis (corneal ulcer) in patients who are unconscious. | To meet ADLs and enhance the patient’s comfort. | |
| Maintain hourly intake and output chart (including blood loss, urine, nasogastric aspirate, etc). | To assess the fluid balance. | |
| Change the drainage bag, chest drainage bottles, and tubing as required. | To prevent infection. | |
| Assess the bowel action at regular days. | To obtain data pertaining to bowel elimination. | |
| Change intravenous administration set and dressing of puncture site every day. | Prevents infection. | |
| Change ventilator circuit tubing, connections, and adapters every day. | Prevents infection. | |
| Change the tape anchoring ET tube and nasogastric tube. | Prevents infection. | |
| Follow aseptic technique. | Prevents infection. | |
| Encourage the patient and relatives to participate in daily care activities. | Participation gives a feeling of acceptance and increases self-esteem. | |
| Provide family counseling. | Enhances family coping skills. | |
| Keep updating the relatives regarding the patient’s condition and prognosis. | To create an atmosphere of warmth and trust. | |
| Documentation | ||
| 42. | Record the mechanical ventilator mode, setting, vital signs, intake and output, ABG, SPO₂, and patient’s response in flow sheet. | For future reference and planning of care. |
Special Considerations
- Ensure the endotracheal (ET) tube or tracheostomy is secure and positioned correctly.
- Regularly assess for tube obstruction, displacement, or leakage.
- Perform suctioning as needed to clear secretions and maintain airway patency.
- Adjust ventilator parameters based on the patient’s condition and arterial blood gas (ABG) results.
- Monitor tidal volume, respiratory rate, oxygen concentration (FiO₂), and peak inspiratory pressure.
- Set alarms for low tidal volume, high pressure, and apnea detection.
- Maintain strict infection control measures, including hand hygiene and aseptic suctioning.
- Elevate the head of the bed 30–45 degrees to reduce aspiration risk.
- Implement oral care protocols to minimize bacterial colonization.
- Use sedation protocols to ensure patient comfort while avoiding over-sedation.
- Assess for pain and agitation, adjusting medications accordingly.
- Consider daily sedation vacations to evaluate readiness for weaning.
- Perform spontaneous breathing trials (SBTs) to assess the patient’s ability to breathe independently.
- Monitor for signs of respiratory distress during weaning attempts.
- Ensure adequate muscle strength and oxygenation before extubation.
- Provide alternative communication methods for ventilated patients.
- Address anxiety and emotional distress through reassurance and support.
- Involve family members in care discussions to improve patient well-being.
REFERENCES
- Annamma Jacob, Rekha, Jhadav Sonali Tarachand: Clinical Nursing Procedures: The Art of Nursing Practice, 5th Edition, March 2023, Jaypee Publishers, ISBN-13: 978-9356961845 ISBN-10: 9356961840
- Omayalachi CON, Manual of Nursing Procedures and Practice, Vol 1, 3 Edition 2023, Published by Wolters Kluwer’s, ISBN: 978-9393553294
- Sandra Nettina, Lippincott Manual of Nursing Practice, 11th Edition, January 2019, Published by Wolters Kluwers, ISBN-13:978-9388313285
- Adrianne Dill Linton, Medical-Surgical Nursing, 8th Edition, 2023, Elsevier Publications, ISBN: 978-0323826716
- Donna Ignatavicius, Medical-Surgical Nursing: Concepts for Clinical Judgment and Collaborative Care, 11th Edition ,2024, Elsevier Publications, ISBN: 978-0323878265
- Lewis’s Medical-Surgical Nursing, 12th Edition,2024, Elsevier Publications, ISBN: 978-0323789615
- AACN Essentials of Critical Care Nursing, 5th Ed. Sarah. Delgado, 2023, Published by American Association of Critical-Care Nurses ISBN: 978-1264269884
- Ernstmeyer K, Christman E, editors. Nursing Fundamentals [Internet]. 2nd edition. Eau Claire (WI): Chippewa Valley Technical College; 2024. PART IV, NURSING PROCESS. Available from: https://www.ncbi.nlm.nih.gov/books/NBK610818/
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