Evaluation and Long-Term Noninvasive Management:
Infants and Small Children
Needed for Evaluation:
1. Capnograph for end-tidal CO2 (EtCO2)
2. Oximeter for oxygen saturation (O2 sat)
3. Peak flow meter for cough peak flow (CPF)
4. Spirometer for vital capacity (VC) and maximum insufflation capacity (MIC)
The most common pediatric neuromuscular disorders (NMDs) are spinal muscular atrophy (SMA) and Duchenne muscular dystrophy (DMD). There are three types of pediatric NMDs based on severity.
NMD type 1: The child can never sit independently.
NMD type 2: The child can never walk.
NMD type 3: The child will temporarily develop the ability to walk (e.g. DMD, SMA type 3).
NMD type 4: Adult onset.
All pediatric NMDs, including the SMAs, are types 1 through 4. Infants and small children should have their end-tidal CO2 (EtCO2), oxygen saturation (O2 sat), and “cry” vital capacity (VC) checked every 3 to 6 months. All children with NMD types 1 and 2 should have oximeters and mechanical insufflation-exsufflation devices (MIE) in the home to use during upper respiratory tract infections (URIs). All children with NMD type 3 need oximeters and MIE and need to use the oximetry feedback protocol once their VCs have plateaued and begin to decrease if not sooner (see plateau VC).
Whether using sleep nasal noninvasive ventilatory support (NVS) or not, on every routine outpatient visit, assessment of end-tidal CO2, O2 sat, and cry VC is monitored. EtCO2 and O2 sat are rarely abnormal unless the child was unfortunately treated at home with supplemental oxygen therapy instead of NVS. Rarely infants, but occasionally somewhat older children treated with oxygen, and especially those who are overweight or have severe scoliosis, may have elevated CO2. They can require NVS or need to have their NVS settings adjusted upwards. Elevated CO2 in children usually warrants sleep nasal NVS. Low O2 sat with normal or low CO2 level is usually an indication of airway secretion congestion or severe scoliosis. The former warrants oximetry feedback protocol management and the latter usually does not warrant any treatment unless O2 sat is less than 96%.
Infants cannot cooperate with spirometry measurements but a cry VC of 50 mL or more for a child with paradoxical breathing (chest sinks in as the belly goes out) indicates the ability to breathe throughout daytime hours provided that sleep nasal NVS is used. In NMD type 1, VCs can increase to a maximum of 100 to 200 mL, and in type 2, invariably exceed 200 mL.
No child with NMD types 1 or 2 have adequate cough peak flows to clear airway secretions, so they all need the oximetry feedback protocol when sick with an upper respiratory tract infection. Like adults, a broad spectrum antibiotic may be helpful to prevent a community-acquired pneumonia. Like adults, unless dehydrated or with a high fever, children are usually better off remaining home with care providers administering the oximetry feedback protocol unless the O2 sat baseline falls and stays below 95%. In this case, hospitalization is warranted because of the risk of a sudden airway mucus plug causing respiratory arrest. Children with pneumonia and decreased baseline O2 sat recover quicker when intubated and can be successfully extubated to continuous (C)NVS and MIE without need to resort to tracheotomy (see centers for noninvasive respiratory management). We now have numerous patients with SMA type 1 who have been CNVS dependent for over 20 years since infancy.
All infants and small children with NMD type 1 and half of those with type 2 have paradoxical breathing and must use sleep NVS.
Polysomnograms and assessments of “ventilation” are irrelevant for infants and small children with NMD type 1 and 2 and paradoxical breathing. If not treated with sleep NVS via nasal interface at inspiratory pressures of 16 to 22 cm H2O, their lungs will not grow and they will develop severe chest deformity including “pectus excavatum”.
About 10% of NMD type 1 children are so severely weak that they become dependent on CNVS before 5 months of age. When nasal NVS is taken off, their O2 sat decreases immediately and without ventilatory support, death would occur in a few minutes. Generally, physicians incorrectly believe that tracheostomy tubes are necessary for these children to survive; however, this is not always true (see outcomes of spinal muscular atrophy).
From diagnosis of paradoxical breathing, children are placed on a portable ventilator (e.g. Trilogy 100[TM]) on continuous mandatory ventilation mode (CMV mode) generally with an active circuit with pressure settings of 18 to 20 cm H2O and back-up rate appropriate for age. No expiratory pressure (PEEP or EPAP) is necessary. They must use NVS during sleep and the parents should observe that it has been set up such that every breath the child takes is augmented by the ventilator. The child must be “in synchrony” with the machine so that when the belly goes out, the chest does as well. Parents are trained to put on the nasal interface and told to accustom the infant to it by initially putting it on while the infant is in deep sleep, then to gradually turn on and turn up the NVS until full 16 to 20 cm H2O settings are reached within a few days. The care provider must see that the chest expands each time the belly goes out (diaphragm contraction). Usually within one week, the infant will no longer want to fall asleep until using nasal NVS. The more the chest expands the better.
Infants already placed on bi-level PAP by other physicians can have their expiratory EPAP settings minimized to 4 cm H2O and their inspiratory IPAP settings increased so that the span (IPAP minus EPAP) is about 16 to 20 cm H2O ("high-level BiPAP"), but ideally, the infant should be switched to pressure-control settings without EPAP. Pressure control of 16 cm H2O adds to one’s breath the same amount of air as would bi-level PAP at IPAP of 20 and EPAP of 4 cm H2O. This will not only maintain normal lung ventilation and blood gases, but promote more normal lung and chest wall growth.
The goal of sleep NVS is to support lung growth and development and to rest respiratory muscles and assist or support breathing and not to treat “sleep disordered breathing” or central and obstructive apneas and hypopneas. This is why these children do not need polysomnograms. Before beginning NVS, these infants often perspire and flush during sleep because of their work of breathing and this is relieved by NVS.
As for adults, all sedating medications and supplemental oxygen must be avoided. They are not a substitute for NVS and MIE. Indeed, they must never be used unless the patient is intubated and the lung ventilation controlled invasively.
If when the user awakens and the nasal interface is removed, the nostrils flair and they are in apparent distress, or if the O2 sat decreases below 95% due to underventilation, then the nasal NVS must be continued and extended into daytime hours. Although 10% of NMD type 1 children develop the need for CNVS before 6 months of age, for about 40% of the others, this occurs before 10 years of age.
Infants and children with NMD type 1 are hospitalized and intubated an average of 0.7 times per year until their 3rd birthday, then 0.3 times per year until their 5th birthday, and then less than once every 10 years afterwards. Although many physicians will pressure parents into consenting their children for tracheotomy, these children can almost always be extubated to CNVS and MIE. We recommend that consent not be given and the doctors be given the information needed to do this where you are or that you get your child transferred to a "Center for Noninvasive Respiratory Management." In addition, your infant should be regularly evaluated by a CNVS and MIE specialist.
Even dependent on CNVS and with no measurable VC since infancy, children can live into adulthood without tracheostomy tubes. Parents must firmly refuse to consent to tracheotomy for their child to be managed noninvasively.