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May.26.2022
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Mechanical Ventilation: Neonatal Time-Triggered, Pressure-Limited, and Time-Cycled (Respiratory Therapy)

ALERT

Mechanical ventilation has inherent risks, including infection, barotrauma, volutrauma, bronchopulmonary dysplasia, and lung injury.

Increased levels of supplemental oxygen during mechanical ventilation can result in retinopathy of prematurity and lung injury from excessive arterial oxygen levels.

OVERVIEW

Time-triggered, pressure-limited, and time-cycled mechanical ventilation is a mode that the respiratory therapist (RT) sets to provide a continuous flow of heated and humidified air to the patient through positive pressure ventilation via an artificial airway. This mode of mechanical ventilation is used to support or improve ventilation and oxygenation.

Most neonates are ventilated because of immaturity of lung tissue or respiratory distress syndrome (RDS). The primary goal of mechanical ventilation is to support breathing and oxygenation while using protective lung strategies to minimize potential damage to the neonate’s lungs.

Time-triggered, pressure-limited, and time-cycled mechanical ventilation is achieved using ventilators specifically designed to ventilate neonates using this mode. These ventilators require capabilities, including the ability to generate low tidal volumes (VTs) and low flows and to sense low-flow and low-pressure changes and other very small dynamic changes generated by the patient.

With time-triggered, pressure-limited, and time-cycled mechanical ventilation, inspiration is triggered by time. Expiration is also cycled or initiated by time. However, the breath is limited by pressure, and when a certain pressure is reached, the unnecessary flow is diverted away from the patient.

Mechanical ventilation can produce negative outcomes in the neonatal patient. One concern involves the patient’s head position during care. Research suggests that the head position may affect cerebral hemodynamics and contribute to the development of germinal matrix‐intraventricular hemorrhage (GM‐IVH) in very preterm neonates.undefined#ref3">3 Turning the head toward one side may occlude jugular venous drainage while increasing intracranial pressure and cerebral blood volume.3 It is suggested that cerebral venous pressure is reduced and hydrostatic brain drainage improved if the patient is cared for in the supine, head midline position.3

Neonates ventilated using a volume-targeted mode of ventilation (VTV) were more likely to suffer no lung damage, and had reduced rates of death or complications, including bronchopulmonary dysplasia, pneumothoraces, hypocarbia, severe cranial pathologies, and duration of ventilation compared with patients ventilated using pressure‐limited ventilation (PLV) modes.2

Neonatal ventilation modes can target a set VT as an alternative to traditional PLV using a fixed inflation pressure. VTV aims to produce a more stable VT to reduce lung damage and stabilize the partial pressure of carbon dioxide (PCO2).2

EDUCATION

  • Provide developmentally and culturally appropriate education based on the desire for knowledge, readiness to learn, and overall neurologic and psychosocial state.
  • Explain the purpose and possible complications of mechanical ventilation.
  • Describe and explain the equipment and alarms.
  • Discuss the need for suctioning and explain the procedure to the family.
  • Discuss with the family the role of sedation during the period of mechanical ventilation.
  • Discuss methods the family may use to interact with and calm their neonate.
  • Encourage questions and answer them as they arise.

ASSESSMENT AND PREPARATION

Assessment

  1. Perform hand hygiene before patient contact. Don appropriate personal protective equipment (PPE) based on the patient’s need for isolation precautions or the risk of exposure to bodily fluids.
  2. Introduce yourself to the family.
  3. Verify the correct patient using two identifiers.
  4. Determine the family’s desire to be present during the procedure.
  5. Assess the family’s understanding of the reasons for and risks and benefits of the procedure.
  6. Auscultate breath sounds before placing the patient on mechanical ventilation and assess the chest radiograph for tube placement.
  7. Check for adequate chest rise and for breath sounds in all lung fields.
  8. Assess vital signs and peripheral oxygen saturation (SpO2).

Preparation

  1. Ensure that all necessary equipment is present at the patient’s bedside and functioning properly, including a manual resuscitation bag (MRB) with an appropriate-size mask, pressure manometer (if not built into the MRB), and suction equipment.
  2. Ensure that the endotracheal (ET) tube is secured to the patient with an appropriate securing device.
  3. Position the patient supine with the head of the bed elevated 15 to 30 degrees4 and the head in a position of comfort to avoid placing pressure on the ET tube and ventilator circuit interface.
  4. Consider prone positioning in infants to improve ventilatory status, per the organization’s practice.
  5. Ensure that the ventilator has been appropriately calibrated per the organization’s practice and the manufacturer’s recommendations.
    1. Ensure that the ventilator circuit and humidification device are appropriately assembled on the ventilator and that they are ready for attachment to the patient.
    2. Ensure that all necessary connections are made to connect the ventilator to medical air, oxygen, and electricity (back-up [red] outlets).
  6. Ensure that all the ventilator alarms are functioning appropriately.
  7. Ensure that the ventilator graphics are recording data.
  8. Ensure that the ventilator circuit humidification system is turned on and heating properly with water in the heater chamber and the temperature alarms appropriately set per the organization’s practice and manufacturer’s recommendations.

PROCEDURE

  1. Perform hand hygiene and don gloves. Don additional PPE based on the patient’s need for isolation precautions or the risk of exposure to bodily fluids.
  2. Verify the correct patient using two identifiers.
  3. Explain the procedure to the family and ensure that they agree to treatment.
  4. Ensure that the ventilator is turned on and is close to the patient.
  5. Before attaching the ventilator to the patient, perform a complete ventilator functionality check by checking all initial ventilator and alarm settings.
  6. Confirm ET tube placement, including:
    1. Bilateral breath sounds
    2. Bilateral chest rise
    3. ETCO2 monitoring
  7. Adjust ventilator settings in collaboration with a practitioner or by following the organization’s practice.
    1. Adjust the peak inspiratory pressure (PIP) until the patient’s chest rises.
      Rationale: A useful clinical indicator of adequate PIP is a gentle chest rise with every breath; a gentle chest rise indicates that the patient has normal chest excursion and adequate breath sounds.
      Use the lowest possible PIP to achieve adequate gas exchange and visible chest rise. Avoid excessive PIP to minimize barotrauma.
    2. Adjust the mean airway pressure (MAP), using ventilator waveforms, to a level of support necessary to successfully ventilate the patient with an awareness that the higher the MAP the higher potential for lung injury.
    3. Set positive end-expiratory pressure (PEEP) for an optimal balance between hemodynamics and oxygenation. To improve oxygenation, attempt to titrate PEEP. Start at a range of 3 to 6 cm H2O.1
    4. Set an inspiratory time (0.3 to 0.5 seconds) with an inspiratory:expiratory (I:E) ratio of 1:2, unless the rate is above 60, then an I:E of 1:1.1
    5. Set the mandatory rate as prescribed by the practitioner or following the organization’s practice.
    6. Set the fraction of inspired oxygen (FIO2) to achieve the desired arterial oxygen saturation (SaO2).
    7. Assess radiographic findings and arterial blood gas (ABG) analysis results to determine the appropriateness of the settings.
  8. Attach the ventilator circuit to the patient via the ET tube adapter. Stabilize the ventilator circuit so that it is not pulling on or putting tension on the ET tube.
  9. Ensure that appropriate alarm parameters are set, including low PIP, high PIP, low VT, high VT, high respiratory rate, low minute ventilation, and high minute ventilation.
    Rationale: Changes in lung compliance can alter the VT delivered to the patient and cause volutrauma or hypoventilation.
  10. Observe the patient for signs and symptoms of increased work of breathing or asynchrony.
  11. Ensure that the ventilator circuit, inline suction catheter (if applicable), and other respiratory-related tubing are properly positioned and are not pulling, pushing, or placing undue pressure on the ET tube or forcing it against the patient’s gums or soft palate. The ET tube should begin midline in the mouth with no pressure on the upper or lower lip or gum. Adjust the position placement of the ET tube, per the organization’s practice, ensuring that no tension is placed on the tube.
    Rationale: Pressure on the patient’s lips or gums from the ET tube results in breakdown in the area of contact. Tension or pressure on the tube can result in unplanned extubation or right main stem intubation.
  12. Discard supplies, remove PPE, and perform hand hygiene.
  13. Document the procedure in the patient’s record.

MONITORING AND CARE

  1. Confirm the patient’s chest radiograph for ET tube placement, lung expansion, and signs of disease (e.g., respiratory distress syndrome, pneumonia, pneumothorax).
  2. Perform routine patient assessments per the organization’s practice.
  3. Monitor all activated alarms and address all reasons why they were activated. If the alarms are activated, disconnect the ventilator from the patient to rule out equipment malfunction while manually ventilating the patient.
  4. Monitor ET tube placement by documenting the centimeter mark at the gum line and monitor skin integrity around the tape and tube-securing device at least once per shift.
  5. Monitor the patient for signs and symptoms of changes in oxygenation and ventilation, including lung sounds.
  6. Monitor the patient’s need for ET tube suctioning and other therapeutic interventions.
  7. Monitor the patient for hypoxemia, hypercarbia, asynchrony, changes in chest wall compliance, and readiness to wean.
  8. Monitor the patient’s vital signs, SpO2, skin color, work of breathing, adequacy of chest excursion, and chest radiography findings.
  9. Monitor SaO2 values and intervene per the organization’s practice.
  10. Monitor ABG values as indicated. In general, blood gas specimens are obtained after initiation of assisted ventilation, after significant changes in ventilation settings, and with changes in the patient’s condition. Report critical values per the organization’s practice.
  11. Monitor the patient for signs of auto-triggering or auto-PEEP or other signs of ventilator dyssynchrony.
  12. Monitor any fluctuation or trends in ventilator measurements, such as VT, minute ventilation, or other trends that may signify a need for changes in ventilator support.
  13. Provide oral care as part of a ventilator bundle to reduce the incidence of ventilator associated events.
  14. Respond immediately to ventilator alarms and watch for changes and fluctuations in prescribed settings that can mean water in the tubing or a need for suctioning. Increasing or decreasing VT at any given PIP indicates changes in lung compliance. If the low-pressure or low-volume alarm sounds, disconnect the patient from the ventilator and attempt to manually resuscitate the patient with an MRB at the same PIP and PEEP as set on the ventilator.
    Rationale: An alarm may be associated with the need for suctioning, the need to drain water from the tubing, or a disconnection of the tubing.
  15. Monitor the patient for signs of unplanned extubation, including sudden deterioration in clinical status, abdominal distention, crying, decreased chest wall movement, breath sounds in the abdomen, agitation, cyanosis, or bradycardia.
  16. Observe the patient for signs and symptoms of pain. If pain is suspected, report it to the authorized practitioner.
  17. Collaborate with team members when scheduling a sedation holiday for a spontaneous breathing trial as part of establishing a readiness for weaning per the organization’s practice.

EXPECTED OUTCOMES

  • Adequate oxygenation and ventilation
  • Maintenance of adequate pH and arterial partial pressure of carbon dioxide
  • Oxygenation and ventilation without lung injury
  • Hemodynamic stability
  • Proper placement of ET tube
  • Mobilization and removal of secretions
  • Discontinuance of mechanical ventilation as soon as the patient is physiologically ready

UNEXPECTED OUTCOMES

  • Inadequate ventilation and oxygenation (hypoxemia, hypercarbia, acidosis, alkalosis)
  • Lung overinflation (air-leak syndrome)
  • Acute lung injury (barotrauma, volutrauma, or progression of lung disease)
  • Atelectasis
  • Hemodynamic instability
  • Unplanned extubation or malposition of ET tube
  • Ventilator-associated events
  • ET tube obstruction
  • Inadequately managed pain and agitation from the ET tube or hypoxemia

DOCUMENTATION

  • Education
  • Cardiopulmonary assessment
    • Vital signs
    • Lung sounds
    • Work of breathing
    • Capillary or arterial blood gas results
    • SaO2
    • SpO2
  • Tube placement and centimeter marking at level of the patient’s gums
  • Last change of tube holder and notation of any pressure spots
  • Date and time of and the patient’s response to initiation of ventilator assistance
  • Length of time of spontaneous breathing trial
  • Weaning protocol success
  • Sedation requirements
  • Ventilator settings
    • FIO2
    • Set rate
    • Total rate
    • PIP
    • Inspiratory time
    • VT generated
    • Minute ventilation
    • I:E ratio
    • PEEP
  • Alarm settings
  • Characteristics of ET tube secretions
  • Patient’s response to suctioning
  • Assessment of breath sounds after suctioning
  • Additional interventions and patient’s response
  • Comfort assessment and interventions
  • Unexpected outcomes and related interventions

REFERENCES

  1. Chipman, D.W. (2021). Chapter 54: Neonatal and pediatric respiratory care. In R.M. Kacmarek, J.K. Stoller, A.J. Heuer (Eds.), Egan’s fundamentals of respiratory care (12th ed., pp. 1212-1242). St. Louis: Elsevier.
  2. Klingenberg, C. and others. (2017). Volume‐targeted versus pressure‐limited ventilation in neonates. Cochrane Database of Systematic Reviews, 10, Art. No.: CD003666. doi:10.1002/14651858.CD003666.pub4 (Level I)
  3. Romantsik, O., Calevo, M.G., Bruschettini, M. (2020). Head midline position for preventing the occurrence or extension of germinal matrix‐intraventricular hemorrhage in preterm infants. Cochrane Database of Systematic Reviews, 7, Art. No.: CD012362. doi:10.1002/14651858.CD012362.pub3 (Level I)
  4. Walsh, B.K., Chatburn, R.L. (2019). Chapter 17: Invasive mechanical ventilation of the neonate and pediatric patient. In B.K. Walsh (Ed.), Neonatal and pediatric respiratory care (5th ed., pp. 301-337), St. Louis: Elsevier.

ADDITIONAL READINGS

Elshiekh, E. and others. (2020). Effect of change in newborn’s position during mechanical ventilation on oxygenation. Egyptian Journal Of Hospital Medicine, 80(3), 997–1002.

Kacmarek, R.M. (2021). Chapter 49: Initiating and adjusting invasive ventilatory support. In R.M. Kacmarek, J.K. Stoller, A.J. Heuer (Eds.), Egan’s Fundamentals Of Respiratory Care (12th ed., pp. 1072-1104). St. Louis: Elsevier.

Elsevier Skills Levels of Evidence

  • Level I - Systematic review of all relevant randomized controlled trials
  • Level II - At least one well-designed randomized controlled trial
  • Level III - Well-designed controlled trials without randomization
  • Level IV - Well-designed case-controlled or cohort studies
  • Level V - Descriptive or qualitative studies
  • Level VI - Single descriptive or qualitative study
  • Level VII - Authority opinion or expert committee reports
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