Neonatal Mechanical Ventilation: An Overview (2024)

Neonatal mechanical ventilation is a critical medical intervention employed to support the respiratory needs of newborns facing life-threatening respiratory distress.

This essential technique involves the use of mechanical ventilators to provide controlled and regulated airflow into the infant’s lungs.

This article breaks down the key aspects of neonatal mechanical ventilation, its indications, techniques, and the challenges it presents in providing the best possible care to these fragile patients.

What is Neonatal Mechanical Ventilation?

Neonatal mechanical ventilation refers to the medical process of using a mechanical ventilator to assist or fully take over the breathing process for newborn infants who are unable to breathe adequately on their own. This can be due to a variety of reasons, such as prematurity, respiratory distress syndrome, congenital abnormalities, or other medical conditions affecting the lungs or airways.

In neonatal mechanical ventilation, a machine delivers a controlled flow of air or oxygen to the infant’s lungs. The ventilator can be set to various modes depending on the infant’s condition and needs.

Indications

Indications for neonatal mechanical ventilation are varied and depend on the specific respiratory needs of the newborn.

Generally, mechanical ventilation is indicated when a newborn has significant respiratory distress or failure and cannot maintain adequate oxygenation and ventilation on their own.

Here are some of the common indications:

• Respiratory Distress Syndrome (RDS): Common in premature infants, RDS is caused by a deficiency of surfactant, a substance that helps keep the airways open.
• Apnea of Prematurity: Inability of premature infants to maintain regular breathing, leading to frequent pauses in breathing.
• Bronchopulmonary Dysplasia (BPD): A chronic lung disease that affects newborns, especially those who are premature and have been treated with oxygen and mechanical ventilation.
• Meconium Aspiration Syndrome: Occurs when a newborn breathes in a mixture of meconium (first feces) and amniotic fluid, leading to lung inflammation and blockage.
• Persistent Pulmonary Hypertension of the Newborn (PPHN): A condition where the blood vessels in the lungs do not expand after birth, leading to high pressure in the lungs and inadequate oxygenation.
• Congenital Diaphragmatic Hernia (CDH): A birth defect where a hole in the diaphragm allows abdominal organs to move into the chest, impeding lung development.
• Pneumonia or Sepsis: Infections that affect the lungs, making it difficult for the newborn to breathe effectively.
• Neurological Conditions: Conditions like hypoxic-ischemic encephalopathy where the brain’s control over breathing is compromised.
• Airway Anomalies: Congenital anomalies of the airway that impede breathing.
• Cardiac Abnormalities: Certain heart conditions that lead to poor oxygenation or respiratory distress.
• Surgical Procedures: Infants undergoing major surgery may require mechanical ventilation during and after the procedure.

Note: In all these conditions, the primary goal is to ensure adequate oxygenation and ventilation to support the infant’s other organs and systems while minimizing potential lung injury. The decision to initiate mechanical ventilation is made by a team of neonatologists and other specialists based on a thorough evaluation of the infant’s condition.

Modes

The modes of neonatal mechanical ventilation refer to the different ways in which mechanical ventilators can be set to assist or fully control an infant’s breathing.

Each mode is designed to cater to specific needs based on the infant’s lung function and medical condition.

Here are some commonly used modes:

• Continuous Positive Airway Pressure (CPAP): CPAP delivers a continuous level of positive pressure to the airways throughout the breathing cycle. This helps keep the airways open and can be used in infants who can breathe on their own but need extra support to keep their airways open.
• Assist/Control Ventilation (A/C): In this mode, the ventilator delivers a preset number of breaths per minute. If the infant initiates a breath, the ventilator will provide support. If the infant does not breathe spontaneously, the ventilator will deliver the set number of breaths.
• Synchronized Intermittent Mandatory Ventilation (SIMV): SIMV delivers a set number of mandatory breaths synchronized with the infant’s own breathing efforts. Between these mandatory breaths, the infant can breathe spontaneously with or without additional support.
• Pressure Support Ventilation (PSV): PSV provides a preset level of pressure support for each spontaneous breath the infant takes, reducing the work of breathing.
• High-Frequency Oscillatory Ventilation (HFOV): HFOV delivers very small breath volumes at extremely high rates (hundreds of breaths per minute). It’s often used for infants with severe lung disease to minimize lung injury.
• High-Frequency Jet Ventilation (HFJV): Similar to HFOV, HFJV delivers rapid, small bursts of air to the lungs. It’s used for specific types of lung problems.
• Adaptive Support Ventilation (ASV): ASV is an advanced mode that automatically adjusts ventilation parameters based on the infant’s needs and can be used for both controlled and assisted ventilation.

Note: The choice of ventilation mode is based on factors such as the infant’s gestational age, the cause of respiratory failure, lung mechanics, and the individual response to ventilation. The goal is always to provide adequate ventilation and oxygenation while minimizing potential harm to the lungs.

Basic Mechanics of Neonatal Mechanical Ventilation

Understanding the basic mechanics of neonatal mechanical ventilation involves several key concepts that are essential to ensure effective and safe respiratory support for newborns.

This includes the following:

• Inspiration: During mechanical ventilation, inspiration is the phase where the ventilator pushes air into the lungs. This can be achieved through various methods, such as delivering a set volume (volume-controlled) or a set pressure (pressure-controlled).
• Expiration: Expiration is generally a passive process where the lungs return to their resting state after being expanded, allowing air to flow out. In some ventilators, a positive end-expiratory pressure (PEEP) is maintained to prevent alveolar collapse.
• Compliance: Compliance refers to the elasticity or stretchability of the lungs and thoracic cage. It determines how much the lungs will expand for a given increase in air pressure. Low compliance, seen in conditions like RDS, means the lungs are stiff and more pressure is needed for expansion.
• Resistance: Resistance is the opposition to airflow within the respiratory system. High resistance can be due to narrowed airways, secretions, or bronchospasm. In mechanical ventilation, more pressure may be needed to overcome increased resistance.
• Surface Tension: Inside the alveoli, surface tension (created by the liquid-air interface) tends to cause alveolar collapse. Surfactant, naturally produced in the lungs, reduces this tension and helps keep the alveoli open. Premature infants often lack sufficient surfactant, increasing the risk of alveolar collapse.
• Work of Breathing: This term describes the effort required for inhalation and exhalation. In conditions where compliance is reduced or resistance is increased, the work of breathing is higher. Mechanical ventilation aims to reduce this work by assisting or taking over the breathing process.
• Time Constant: The time constant of the lung is a product of compliance and resistance. It indicates how quickly the lungs can fill and empty. A short time constant means the lungs fill and empty quickly, while a long time constant means slower filling and emptying.

In neonatal mechanical ventilation, these principles are applied to manage the delicate balance of delivering adequate oxygen and removing carbon dioxide while minimizing potential injury to the underdeveloped and often fragile lungs of newborns.

Ventilator settings are adjusted based on these physiological factors to provide optimal respiratory support.

Basic Mechanisms of Gas Transport in Neonatal Mechanical Ventilation

The basic mechanisms of gas transport in neonatal mechanical ventilation involve several important concepts that are crucial for understanding how ventilators support respiratory function in newborns.

This includes the following mechanisms:

• Tidal Volume (Vt): Tidal volume is the amount of air that moves in and out of the lungs with each breath. In mechanical ventilation, it’s critical to set the appropriate tidal volume to ensure adequate gas exchange without causing lung injury, especially in the delicate lungs of neonates.
• Minute Ventilation (Ve): Minute ventilation is the total volume of air entering or leaving the lungs per minute. It’s calculated as tidal volume multiplied by the respiratory rate. Minute ventilation is a critical parameter for ensuring adequate removal of carbon dioxide (CO2).
• Anatomic Dead Space: This refers to the part of the respiratory system where gas exchange does not occur, primarily the trachea and bronchi. In neonates, the anatomic dead space is proportionally larger than in adults, affecting ventilation efficiency.
• Alveolar Dead Space: Alveolar dead space is the portion of the lungs where alveoli are ventilated but not perfused with blood, and thus no gas exchange occurs. This can happen due to various pathological conditions.
• Physiologic Dead Space: Physiologic dead space is the sum of anatomic and alveolar dead spaces. It represents the total volume of the lungs that does not participate in gas exchange. In healthy lungs, physiologic dead space is primarily the anatomic dead space.
• Oxygenation: Oxygenation refers to the process of adding oxygen to the body. In mechanical ventilation, oxygenation is achieved by delivering air with an appropriate concentration of oxygen. The effectiveness of oxygenation is assessed by measuring blood oxygen levels.
• Ventilation: Ventilation is the process of moving air in and out of the lungs. In mechanical ventilation, this involves the artificial regulation of tidal volume and respiratory rate to ensure adequate removal of CO2 and maintenance of normal blood pH.
• Perfusion: Perfusion refers to the blood flow through the lungs. It is crucial for gas exchange as it brings deoxygenated blood to the alveoli where oxygen is absorbed and CO2 is released. Adequate perfusion is necessary for effective oxygenation.

These concepts form the basis of how neonatal mechanical ventilation supports the respiratory system.

The primary goal is to ensure effective gas exchange—delivering enough oxygen to the body and removing CO2—while minimizing potential damage to the newborn’s lungs.

Careful adjustment and monitoring of ventilator settings, in conjunction with regular assessment of the infant’s blood gases and overall condition, are essential for successful mechanical ventilation in neonates.

Goals of Neonatal Mechanical Ventilation

The goals of neonatal mechanical ventilation are multifaceted, aimed at ensuring survival and minimizing complications in newborns who require respiratory support.

These goals include:

• Adequate Oxygenation: Ensuring that the baby’s tissues and organs receive sufficient oxygen. This is crucial for the proper functioning and development of vital organs, especially the brain and heart.
• Adequate Ventilation: Maintaining appropriate levels of carbon dioxide (CO2) in the blood. Both excessively high and low levels can be harmful.
• Lung Protection: Avoiding injury to the delicate lung tissues of the newborn, which can be caused by excessive pressure or volume delivered by the ventilator.
• Preventing Complications: Reducing the risk of ventilator-associated complications, such as infection, lung injury, and chronic lung disease (like bronchopulmonary dysplasia in preterm infants).
• Supporting Natural Growth and Development: Facilitating normal growth and development, which includes minimizing sedation to allow for interaction and feeding, when possible.
• Facilitating Weaning and Extubation: Gradually reducing ventilator support as the infant’s condition improves, aiming for timely removal of the ventilator and endotracheal tube to promote normal breathing and feeding.
• Family Involvement and Support: Involving the family in the care process, providing emotional support and education about the infant’s condition and care needs.

Note: The approach to achieving these goals is highly individualized, based on the specific needs and responses of each infant. It requires a skilled multidisciplinary team, including neonatologists, nurses, respiratory therapists, and other specialists, to constantly monitor and adjust the treatment plan.

Neonatal Mechanical Ventilation Practice Questions

1. What are the indications for neonatal mechanical ventilation?
Ventilator and oxygenation failure

2. What is considered ventilatory failure in neonates?
PaCO2 less than 60 mmHg and a pH less than 7.24.

3. What is considered oxygenation failure in neonates?
PaO2 less than 50 on an FiO2 greater than 80%, or an SaO2 less than 88% on an FiO2 greater than 80%.

4. How can you treat oxygenation failure in neonates?
By administering CPAP or PEEP.

5. What is the most common cause of a decreased FRC?
Infant Respiratory Distress Syndrome (RDS)

6. What is required for less mature and smaller infants who need suctioning and have an unstable pulmonary condition?
Intubation

7. In general, the PaO2 should be kept between what?
60-70 torr

8. What could cause a sudden decrease in the CPAP level to zero?
A disconnection

9. When a neonate’s ABG and vital signs indicate the need for mechanical ventilation, most neonatal patients require what?
Time-triggered, pressure-limited, time-cycled mechanical ventilation.

10. Volume-cycled ventilation can be used on infants that weigh more than what?
More than 10 kg

11. What is the typical tidal volume goal for a neonatal patient?
4-6 mL/kg

12. What is a general rule to estimate the depth of intubation?
Add six to the body weight in kilograms.

13. Because delivered volumes are so small when volume ventilating infants and small pediatric patients, what must be taken into account?
The tubing compression factor.

14. What factor allows us to consider the volume that is lost within the circuit?
Compressible volume

15. What are the neurological reasons for mechanical ventilation in neonates?
Apnea, apneic periods leading to hypoxemia and bradycardia, intracranial hemorrhage, and drug depression.

16. What are the pulmonary conditions for mechanical ventilation in neonates?
Infant respiratory distress syndrome (RDS), diffuse pneumonia, pulmonary edema, meconium aspiration, diaphragmatic hernia, prophylactic use, cyanotic congenital cardiac defect, persistent pulmonary hypertension of the neonate, and post-op after major thoracic or abdominal surgery.

17. The greatest challenge presented in the care of a critically ill infant on mechanical ventilation is to provide adequate gas exchange without causing oxygen toxicity due to what?
A high FiO2 or pulmonary barotrauma.

18. Delivering more than 50% oxygen for more than how many hours will increase the risk of pulmonary oxygen toxicity in a neonate?
Giving 50% oxygen for more than 48-72 hours.

19. What will occur if you give the neonate more than 80% oxygen?
The poorly ventilated alveoli will have all the oxygen absorbed leading to denitrogenating absorption atelectasis.

20. You should keep the PaO2 below 80 mmHg to reduce the risk of what?
Retinopathy of prematurity (ROP)

21. What setting should you set first on the ventilator?
PIP

22. How do you set the PIP setting for an infant?
Set it initially at 20-25 cmH2O, but it may be increased to 35-45 cmH2O.

23. Infants with decreased compliance may need a higher PIP, so is should be set at what?
25-30 cmH2O

24. For infants with increased RAW and normal lung compliance, you should set the PIP at what?
Less than 20 cmH2O

25. How should the PIP be set in premature infants?
Less than their gestational age

26. What can you adjust to control the PaCO2?
PIP

27. How is the rate set for term infants?
20-30 breaths/minute

28. The rate is most commonly used to adjust the PaCO2 after what is set appropriately?
PIP

29. Using a higher rate and lower PIP can decrease the risk of what?
Barotrauma

30. What ventilator setting is set third for neonates?
I-time

31. What should the I-time be set at for a term infant?
0.5-0.6 seconds

32. After you adjust the primary settings for a neonate, you can proceed to set what?
Flow, FiO2, PEEP, and mode.

33. What should the flow for a neonate be set at?
5-8 L/min

34. If the pressure manometer needle swings into a negative range during inspiration, you should increase the flow, but be careful because too much flow leads to what?
Inadvertent PEEP

35. The FiO2 for a neonate on mechanical ventilation should be set at what?
40%

36. The PEEP for a neonate on mechanical ventilation should be set at what?
It should be set between 2-4 with a range of 2-10 cmH2O.

37. What mode is preferred for neonates?
Intermittent Mandatory Ventilation (IMV)

38. Obstructions or uneven airflow in neonates can result in what?
Hypoxemia, air trapping, auto-PEEP, and an increased risk of barotrauma.

39. What are two key clinical goals in treating neonates with increased RAW?
Minimize turbulence during inspiration by reducing the inspiratory flow, and give a long enough expiratory time to prevent air trapping.

40. It usually takes 3 time constants to exhale to 95% of the delivered volume, and how many to exhale completely?
5 time constants

41. Infants with normal compliance and increased resistance have long time constants and, as a result, are at risk for what?
Air trapping and auto-PEEP

42. You should adjust the FiO2 to keep the PaO2 in a preferred range of what?
50-70 mmHg

43. As lung compliance improves, the I-time should be decreased for what two reasons?
1) The alveolar pressure is more readily transmitted throughout the lungs and may decrease venous return to the heart, resulting in decreased cardiac output; and 2) The lungs become more prone to barotrauma or volutrauma.

44. Excessive PEEP can cause barotrauma, which can cause what?
PIE, pneumothorax, or pneumomediastinum.

45. When should intubation and surfactant therapy be considered for a neonate?
If the infant with RDS is having recurrent periods of apnea, persistent respiratory acidosis, or if they have a low PaO2 while on more than 50% with nasal CPAP.

46. What is the primary mode of mechanical ventilation for neonates?
Pressure-controlled ventilation

47. Pressure-controlled ventilation is characterized by what?
A preset pressure.

48. Ventilation can also be achieved using a preset volume in what mode?
Volume-controlled ventilation

49. What initial tidal volume should be used for infants on volume-limited ventilation?
5 mL/kg

50. The smaller the infant, the higher the incidence of what?
Barotrauma

51. What is high-frequency ventilation (HFV)?
A mode that delivers small tidal volumes at very high rates with low pressure to reduce the risk of barotrauma.

52. HFV appears to be more useful in treating what?
RDS and pneumonia

53. HFV rates range from what?
150-1,800 cycles per minute

54. 1 Hertz equals what?
60 cycles or breaths/min, or 1 cycle (breath) per second.

55. High-frequency positive pressure ventilation (HFPPV) has been found to improve what?
It reduces the incidence of pneumothorax and asynchrony.

56. HFPPV is indicated for what?
Hypoxemia or hypercapnia when conventional methods fail.

57. What is the clinical use for HFPPV?
In cases of severely none compliant lungs an increase in rate to increase minute volume, which allowed the tidal volume is smaller with lower PIP.

58. What are the indications for high-frequency jet ventilation (HFJV)?
Severe pulmonary disease complicated by air leaks, pulmonary interstitial emphysema, pulmonary hypoplasia, restrictive lung diseases, and persistent pulmonary hypertension.

59. Why is auscultation difficult during HFJV?
It is difficult to hear due to the constant vibration and noise produced by the ventilator.

60. What must be monitored during HFJV?
Fluid, electrolytes, and neurological status.

61. What are the indications for high-frequency oscillatory ventilation (HFOV)?
Failure of conventional ventilation, severe RDS, congenital diaphragmatic hernia, diffuse alveolar disease, non-homogeneous lung disease, air leaks, and pulmonary hypoplasia.

62. How is the incidence and severity of bronchopulmonary dysplasia affected when HFOV is used with surfactant replacement therapy during the first hours of life?
It is reduced.

63. What is extracorporeal membrane oxygenation (ECMO)?
ECMO is a life-supporting intervention that provides both cardiac and respiratory support to individuals whose heart and lungs are unable to sufficiently provide oxygenation to the body’s needs. It works by pumping and oxygenating a patient’s blood outside the body, allowing the heart and lungs to rest and recover.

64. What pathologies may be considered for ECMO in neonates?
Persistent pulmonary hypertension, meconium aspiration syndrome, sepsis, and congenital diaphragmatic hernia.

65. ECMO is not recommended for which infants?
Infants that are less than 34 weeks of gestational age, weighing less than 2,000 g, and those having evidence of intracerebral hemorrhage.

66. Why are patients with intracerebral hemorrhage not candidates for ECMO?
Because of the need for systemic heparinization during the procedure.

67. What must a candidate for ECMO have?
A reversible lung disease and free of significant cardiac disease.

68. What are the most common complications of ECMO?
They are related to bleeding from heparinization.

69. What are the physiological objectives of neonatal and pediatric mechanical ventilation?
Decrease VILI, decrease work of breathing, optimize lung volumes, improve oxygenation, and improve alveolar ventilation.

70. What are the normal values for compliance in newborns?
2.5-5 mL/cmH2O

71. What factors increase airway resistance in neonates?
Bronchospasm, airway secretions, edema of the airway walls, inflammation, and the use of artificial airways.

72. What are the partial ventilatory support modes for neonates?
CPAP, PSV, and SIMV.

73. What are the indications for CPAP in neonates?
Respiratory rate more than 30% above normal, paradoxical chest wall movement, grunting, nasal flaring, cyanosis, CO2 less than 60, and a pH greater than 7.25.

74. What are the contraindications for CPAP in neonates?
Prolonged apnea, untreated pneumothorax, hemodynamically unstable, unilateral pulmonary problem, mouth/face abnormalities, or post-surgery.

75. Which laryngoscope blade is often preferred for neonates?
Miller (straight blade)

Final Thoughts

Neonatal mechanical ventilation plays a pivotal role in the care of newborns struggling with respiratory distress. This life-saving intervention requires precision and expertise from healthcare professionals, as it can significantly impact the outcomes of these vulnerable infants.

While it is a vital tool in neonatal care, it also comes with inherent risks and complexities that demand careful consideration.

The ongoing research and advancements in this field continue to improve the efficacy and safety of neonatal mechanical ventilation, ultimately contributing to better outcomes and a brighter future for these tiny patients.