Introduction
In this episode, we review non-invasive ventilation in the NICU, respiratory support without an endotracheal tube, but rather with a nasal cannula or face mask.
If your baby currently has or had Respiratory Distress Syndrome (RDS), the chances are quite high that they are currently or were previously on at least one of the different modes of non-invasive ventilation, either nIMV or NIPPV, CPAP, HFNC, LFNC.
After listening, you will walk away with a much better understanding of the different options of non-invasive ventilation, why one method may be chosen over another, how they will be beneficial to your baby, as well as some of the potential complications.
Tune in to gain a better understanding of the parameters set on each of the different modes including but not limited to rate, PIP, PEEP, i-time, L/min and FiO2.
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Free Image of NICU Equipment from Head to Toe
Episode 11
Why is Non-Invasive Ventilation used in the NICU
Respiratory support can be provided to babies in the NICU either with invasive ventilation or non-invasive support. Invasive ventilation is with a breathing tube or endotracheal tube and is considered invasive, because it is an indwelling piece of equipment inside the body. An invasive device is any medical device that is introduced into the body, either through a break in the skin or through an opening in the body. With an endotracheal tube, it is inserted by a NNP, Neonatologist, or transport RN through the baby’s mouth down into the trachea.
Non-invasive ventilation, is provided to the baby either via nasal prongs or a nasal mask. Our goal as NICU providers is not different from providers of other inpatient care areas in that we are always attempting to minimize the number of invasive pieces of equipment in our patients. Meaning, if the patient does not medically need the invasive line or tube, we want to remove it! Any piece of invasive equipment is a quick source of entry for hospital-acquired infections for our patients.
As we mentioned in our last episode, despite the benefits of invasive ventilation in terms of survival for preterm infants, it does cause barotrauma and volutrauma and it is an important risk factor for BPD. The diagnosis of BPD is associated with neurological sequelae including but not limited to cerebral palsy, visual and hearing impairment, developmental delays as well as chronic respiratory problems.
Not only does invasive ventilation cause lung damage, but it is also a source of entry for organisms in babies who are intubated in the NICU. So, as a provider, we closely monitor blood gas results, parameters on the ventilator, and how the baby appears clinically to wean the ventilator settings with the goal of extubation.
Non-invasive ventilation in general is a method of maintaining the Functional Residual Capacity or the volume that remains in the lungs after a normal, passive exhalation without endotracheal intubation. It also augments the baby’s spontaneous respiratory effort. Non-invasive ventilation may be used as the initial treatment for an infant with RDS or as a “bridge” after extubation to support spontaneous breathing as well as the treatment of apnea of prematurity.
How to determine if an infant is ready to be weaned to Non-Invasive Ventilation
To assist in evaluating extubation readiness, many institutions will do a spontaneous breathing trial. The infant is placed on CPAP via the endotracheal tube without a rate for a set period of time with continuous monitoring of the baby’s heart rate and oxygen saturation levels. The infant will pass the SBT or spontaneous breathing trial if they do not have any desaturations or heart rate drops within the allotted time. If the SBT is successful, it can be helpful in predicting successful extubations.
Once the provider makes the decision to extubate the infant, most babies will then be placed on a mode of non-invasive ventilation. Now, there are some infants, typically either post-surgical or term infants who can be extubated from the ventilator straight to room air without the need for non-invasive ventilation or CPAP. Whereas other infants will need to be placed on additional support post-extubation.
Review of Respiratory Distress Syndrome in Newborns
For a full detailed review of RDS in Newborns and further explanation of some of the common terminology and pathophysiology behind RDS, head to the show notes from Episode 8: Take a Deep Breath – Into Respiratory Distress Syndrome in Newborns.
We also put together a Free Graphic to help you understand RDS in newborns as well! Go and grab it now!
Oxygen blender use in the NICU
Often times, babies in the NICU require some additional oxygen with their respiratory support. The FiO2, or fraction of inspired oxygen, is the concentration of oxygen in the gas mixture. The FiO2 is separate from the other settings on the ventilator or respiratory delivery device. All of the invasive modes of ventilation we discussed a couple of weeks ago and most of the non-invasive modes have an oxygen blender attached to the respiratory delivery mode to blend the oxygen given to the baby.
Oxygen is considered a drug and although babies in the NICU often need it, it should be used judiciously to avoid harm. Hyperoxia or excess oxygen in the tissues is associated leads to major morbidities in neonates. Hyperoxia has been shown to lead to retinopathy of prematurity and bronchopulmonary dysplasia.
In the NICU, oxygen saturations are monitored very carefully. The recommended requirements vary from baby to baby and are based on their gestational age. It is typically the bedside NICU nurse who will carefully adjust the FiO2 on the blender based on the baby’s oxygen saturations. In NICUs, a low and high saturation alarm is set to alert the staff if they should consider increasing the FiO2 if the baby is saturating too low, or consider weaning the FiO2 if the baby is saturating too high.
Non-Invasive Mandatory Ventilation (nIMV) or Non-Invasive Positive Pressure Ventilation (NIPPV)
Nasal intermittent mandatory ventilation (nIMV) or it may also be referred to as nasal intermittent positive pressure ventilation (NIPPV) are commonly used in the NICU. The most common form of NIPPV uses peak inspiratory pressures or PIP and shorter inhalation times. It provides intermittent breaths either through short binasal prongs, masks, or long nasopharyngeal tubes.
With NIPPV, it combines the main physiologic advantages of nasal CPAP like stabilization of the alveoli with the positive pressure but it also provides better ventilation with the additional intermittent breaths. NIPPV maintains functional residual capacity (FRC) or the volume that remains in the lungs after a normal, passive exhalation, it facilitates gas exchange, improves lung compliance and airway resistance. With the above benefits, it decreases the baby’s work of breathing and decreases the incidence of apnea.
The provider will modify the different parameters of NIPPV based on the baby, their blood gas results, FiO2 requirement, CXRs, and the baby’s clinical appearance. The adjustable parameters on NIPPV include the respiratory rate, the PEEP, PIP, and i-time.
The respiratory rate on nIMV is the number of breaths delivered to the baby in a minute, typically 20-40. The PEEP, or positive end expiratory pressure, is the positive pressure that is maintained throughout expiration to prevent the alveoli from collapsing. The PEEP also helps to minimize the resistance needed against the increased surface tension. On NIPPV, you will also set a PIP, or peak inspiratory pressure. The PIP, just as its name states, is the predetermined peak pressure reached at the end of inspiration. Each breath that is given to the baby at the set rate has a PIP and a PEEP.
On NIPPV, the PIP and PEEP that has been ordered and displayed on the ventilator may be set higher than what you would typically see with invasive ventilation – this is due to the fact that not all of the set pressure from the PIP and PEEP go directly into the trachea, airway and lungs. With non-invasive ventilation, there is not a complete adequate seal and it does not go directly into the trachea like invasive ventilation with an endotracheal tube. From the nasal cannula or mask, some of the pressure will naturally also go down into the baby’s esophagus and stomach. Therefore, a typical PEEP on non-invasive ventilation may range from 5-8 or even up to 9 and the typical PIP ranges from 18 up to 28. The i-time or inspiratory time is the time it takes to achieve the target pressure and it is typically maintained at 0.5 seconds. There will also be an air-oxygen blender that allows for titration of oxygen.
For weaning on NIPPV, once the baby has consistently low FiO2 requirements and stable blood gases, the provider may begin to wean the settings. As with invasive ventilation, the PIP is typically weaned initially followed by the rate and PEEP.
According to the American Academy of Pediatrics, studies that have compared NIPPV to nasal CPAP have consistently found that NIPPV reduces the rate of extubation failure and the frequency of apnea in preterm infants more than CPAP. NIPPV also has been found to significantly decrease the need for invasive ventilation – especially in the first 72 hours when compared to CPAP as well.
Continuous Positive Airway Pressure (CPAP)
CPAP has been the standard of neonatal respiratory care in the NICU for decades. It was first introduced by Gregory and colleagues back in 1971. CPAP delivers a constant level of positive pressure or PEEP to the baby’s airways which distends the lungs, overcomes alveolar collapse and improves ventilation. CPAP can be delivered via either short binasal prongs, a nasal mask or long nasal prongs.
The ordered PEEP on the CPAP helps to prevent the alveoli from collapsing, it maintains functional residual capacity, facilitates gas exchange, improves lung compliance and airway resistance. Just as with NIPPV, it will also decrease the baby’s work of breathing, decrease the incidence of apnea, and improve ventilation perfusion in babies.
CPAP has different apparatuses from which it can be delivered. A common method used in NICUs in the United States as well as low-income countries is bubble CPAP. Bubble CPAP immerses the end of the respiratory circuit into a column of water from which the baby exhales against, generating bubbles. The length of the immersed tubing determines the level of PEEP or pressure from 4 to 8 cm of water on average. CPAP can also be delivered via a ventilator and the PEEP is set on the ventilator. Whether CPAP is delivered via bubble CPAP or through a ventilator, there will be an air-oxygen blender that allows for titration of oxygen.
Weaning from CPAP is done slowly by decreasing the PEEP by 1 cm of water and closely monitoring for any clinical deterioration. Once the infant is stable on +4 or +5 cm H2O, they can be taken completely off of respiratory support to room air, or may be placed on a High Flow Nasal Cannula. Some NICUs opt to continue CPAP on premature infants until they reach 32 weeks corrected gestational age even if they are stable enough to come off before because CPAP has been found to stimulate lung growth, improve lung function, and help suppress airway hyper-reactivity in premature infants.
Potential complications from NIPPV and CPAP
A few of the potential complications with NIPPV or CPAP are the increased risk for air leaks, nasal irritation or breakdown from the prongs, gastrointestinal perforations, and gastric distention or CPAP belly. Just as I described before, some of the air that enters into the baby’s nostrils will naturally flow into the esophagus as opposed to the trachea and baby’s can have some excessive abdominal distention due to the increased air in their abdomen.
Heated Humidified High Flow Nasal Cannula (HHHFNC)
Heated, humidified, high flow nasal cannula (HHHFNC) delivers heated and humidified gas through bi-nasal prongs that are not meant to occlude the nostrils. HHHFNC is not typically used as a first line of treatment for RDS, but rather as a bridge between CPAP and room air or Low Flow Nasal Cannula. The mixture of oxygen and air is delivered at a flow rate greater than 1 L/min and may go up to 8 L/min. The goal of a HFNC is to provide PEEP or positive end expiratory pressure in a less invasive way compared to CPAP.
The mechanisms of HHHFNC are thought to decrease airway resistance, increase the efficiency of gas exchange by the washout of nasopharyngeal dead space in the upper respiratory tract, and increase functional residual capacity. It also supplies positive distending pressure and improves lung compliance. With the above benefits, it decreases the baby’s work of breathing and it reduces their supplemental oxygen requirement. HHHFNC will also be connected to an oxygen blender to provide a blend of oxygen and air.
One key feature of HHHFNC is the preconditioning of the inspired gas. Since it normally takes metabolic energy for our bodies to warm and humidify the air we breathe, HHHFNC has the advantage of reducing the baby’s energy expenditures. Although CPAP is also typically warmed, studies have revealed that HFNC is warmed a bit more. HHHFNC has also been shown to decrease the amount of nasal septum breakdown and is typically more comfortable for the infant.
Some of the common disadvantages of HHHFNC include the inconsistency of the continuous distending pressure given to the baby that may result in traumatic air dissection. The flow can generate high nasopharyngeal airway pressures in certain circumstances like tightly fitted nasal prongs, high flow rates, and/or a closed mouth. So, many NICUs limit the flow to only 3-4 L as opposed to going up to 8 L/min. Careful attention should be given to the size of nasal prongs used on the baby to allow an adequate leak between the prongs and nares, as well as the use of the lowest effective flow rates.
For weaning with the HHHFNC, it is gradually weaned down by 0.5L or 1L/min based on the baby’s clinical appearance and oxygen requirements.
Low Flow Nasal Cannula (LFNC)
Low Flow Nasal Cannulas deliver oxygen at liter flows of less than 1 L/min. Often times, babies that are on a low flow nasal cannula do not need the positive pressure, but rather they need the supplemental oxygen to keep their saturations in the appropriate range for their gestational age.
A LFNC can either be set up with an oxygen blender for a mixture of air and oxygen with an adjustable FiO2, or possibly without a blender at 100% oxygen based on the baby’s eye exam. Although 100% of oxygen may be given, the baby receives less than 100% once the flow rate and baby’s weight are factored in.
An infant with BPD or bronchopulmonary dysplasia may need to use a LFNC at or near discharge. Bronchopulmonary Dysplasia damages the baby’s lungs and causes scarring. But, a baby’s lungs will continue to grow and the amount of alveoli rapidly increases during the baby’s first 6 months of life. Lung growth and the volume continue to increase a large amount in the first 2 years. So although your baby may need to go home on oxygen, hopefully as their lungs continue to grow, they will eventually no longer need it.
Our son, William did come home on a LFNC. Luckily, he only needed it for one month, but every baby and their lungs are completely different so the length of time will be varied from infant to infant. Although it may be scary to think of having a baby home on oxygen, the hospital will ensure that you are completely supported and prepared. You’ve got this! Just think about how far your baby has already come!
Closing
I hope you have gained some value from our review of non-invasive ventilation in the NICU. Not every baby in the NICU needs respiratory support, but it is quite common for our NICU babies to need some support during their stay. I hope the review of the benefits of each mode of support, as well as when each one is typically used, and the potential complications of NIPPV, CPAP, HHHFNC, and LFNC in the NICU has been helpful. You should now have a better understanding of the different parameters the provider will set with each mode and also how they are typically weaned.
My goal as always is to provide you with the basic knowledge so you have a better understanding of common diagnoses, conditions, and equipment used in the NICU so you feel more comfortable asking questions about your baby. You may now be able to almost predict which mode of respiratory support your baby may be weaned to as they improve.
As I previously mentioned, I strongly recommend if you have not already, go back and listen to Episode 8, Take a Deep Breath – Diving into Respiratory Distress Syndrome in Newborns for a thorough review on RDS and if your baby is intubated, Episode 10, Ventilator Review in the NICU – What Does Positive Pressure, Volume-Targeted, and High Frequency Do?
As always, share our podcast or this particular episode with someone who you feel would benefit from it.
Remember, once empowered with knowledge, you have the ability to change the course.
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