Use of an Expiratory Filter to Reduce
Nosocomial Spread When Treating a COVID
Positive Neonate with bCPAP: A Case Report
Noah Daniel1*, Ghassan Bou Saba1, Navid Roodaki2, Daisy Garcia2, Michelle Dundek1,3, Hena Wadhwa1, Ellie Ng1 and Thomas Burke1,3,4,5
1Vayu Global Health Foundation, Boston, Massachusetts, USA
2locos Training and Regional Medical Center, Department of Pediatrics, San Fernando City, La Union, Philippines
2Massachusetts General Hospital, Global Health Innovation Lab, Department of Emergency Medicine, Boston, Massachusetts, USA
2Harvard Medical School, Boston, Massachusetts, USA
2Harvard T.H. Chan School of Public Health, Boston, Massachusetts, USA
Submission: September 20, 2022; Published: October 13, 2022
*Corresponding author: Noah Daniel, Vayu Global Health Foundation, 22 Welgate Rd, Medford, MA, 02155, USA, Tel: (+1)7038221329
How to cite this article:Noah D, Ghassan Bou S, Navid R, Daisy G, Michelle D, et al. Use of an Expiratory Filter to Reduce Nosocomial Spread When
Treating a COVID Positive Neonate with bCPAP: A Case Report. Acad J Ped Neonatol 2022; 12(2): 555887. 10.19080/AJPN.2022.12.555887
The SARS-CoV-2 virus has caused COVID-19 infections in neonates. Although neonates are usually less severely affected by COVID-19 than adults, they are still at risk for respiratory compromise and transmission of COVID-19 to parents and health care workers. Continuous positive airway pressure (CPAP) is a promising alternative to invasive ventilation for the treatment of infants in respiratory distress due to COVID-19 and other etiologies. However, controlling respiratory virus transmission remains a challenge for neonatal intensive care units (NICUs), particularly those in resource constrained settings. To mitigate COVID-19 aerosol transmission, WHO recommends the use of expiratory filters on aerosol generating procedures such as when providing non-invasive ventilation with CPAP. Expiratory filters have routinely been used when treating neonates with invasive ventilation, but there is a dearth of evidence on the use of expiratory filters during the treatment of neonates with non-invasive ventilation. We describe the use of a novel bubble CPAP (bCPAP) system engineered with an expiratory filter to treat a COVID-19 positive neonate with respiratory distress at Ilocos Training and Regional Medical Center in the Philippines. This case raises awareness of the potential use of expiratory filters during treatment with bubble CPAP to mitigate respiratory virus transmission in resource constrained NICUs.
The SARS-CoV-2 virus has caused COVID-19 infections in neonates. Although neonates are usually less severely affected by COVID-19 than adults, they are still at risk for respiratory compromise and transmission of COVID-19 to parents and health care workers [1data describing the effect of SARS-CoV-2 in this group are scarce, and guidance is variable. We aimed to describe the incidence, characteristics, transmission, and outcomes of SARS-CoV-2 infection in neonates who received inpatient hospital care in the UK. METHODS: We carried out a prospective UK population-based cohort study of babies with confirmed SARS-CoV-2 infection in the first 28 days of life who received inpatient care between March 1 and April 30, 2020. Infected babies were
identified through active national surveillance via the British Paediatric Surveillance Unit, with linkage to national testing, paediatric intensive care audit, and obstetric surveillance data. Outcomes included incidence (per 10 000 livebirths]. Continuous positive airway pressure (CPAP) is a promising alternative to invasive ventilation for the treatment of infants in respiratory distress due to COVID-19 and other etiologies [2-4].
In the age of the COVID-19 pandemic, treatment procedures are expected to work in tandem with infection control protocols. Aerosolized droplets are considered the primary transmission route of COVID-19 and contribute to high COVID-19 infection rates . Therefore, NICU infection management protocols generally call for medical staff to wear PPE (personal protective equipment),
use of expiratory filters during aerosol generating procedures (i.e.
ventilation), and geographic isolation of suspected COVID-19
positive newborns in a designated COVID-19 ward [6-8].
Recommended transmission control measures have limited
applicability for high volume and resource constrained settings.
Practices such as geographic isolation of patients and assignment
of medical providers solely dedicated to infected patients are often
impractical, if not impossible, in overcrowded and understaffed
hospitals [9,10]. Infections are exacerbated by shortages of PPE,
which was already scarce in low resource settings before the
pandemic . Even if staff have access to advanced face masks,
effective protection depends on a COVID-19 positive patient also
wearing a face mask . However, infection source control via
face masks is not practical in newborns . Successful source
control of COVID-19 infected neonates has been achieved in
some cases via expiratory filters placed on invasive ventilator
circuits (i.e., mechanical ventilators). However, broad applicability
in neonates with respiratory distress is limited since invasive
ventilation is infrequently used .
With all the barriers to quality infection transmission control,
it is not surprising that there have been reported cases of COVID-19
transmission from neonates to masked health care workers. In a
NICU in Botswana, three masked healthcare workers contracted
COVID-19 from interactions with an infant being treated with
supplemental oxygen therapy . Horizontal transmission to
other infants in NICUs has been reported in the US .
Although, WHO urges the use of expiratory filters in adult
and pediatric aerosol generating procedures, and there exists
ample documentation of clinicians using invasive ventilators
equipped with expiratory filters to treat neonates, to the best of
our knowledge we present the first case of an infant diagnosed
with COVID-19 who was treated with CPAP equipped with an
expiratory filter [17-20].
Below, we describe the use of a novel bCPAP system engineered
with an expiratory filter to treat a COVID-19 positive neonate with
respiratory distress and reduce nosocomial infections at Ilocos
Training and Regional Medical Center in the Philippines. The
patient’s parents provided written informed consent to publish
this case report.
A 28-year-old G1P1 COVID-19 positive mother delivered a
33-weekgestational age infant who was in respiratory distress
immediately after birth. Birth weight was 1500 g and APGAR
scores were seven and nine at one and five minutes of life. Moderate
intercostal retractions and tachypnea developed shortly after
delivery. The newborn was treated with one L/min of low-flow
unblended oxygen and immediately transferred from a peripheral
hospital to the Ilocos Training & Regional Medical Center’s
(ITRMC) Neonatal Intensive Care Unit in La Union, Philippines. At
ITRMC, an umbilical vein catheter was placed and blood laboratory
analysis revealed mild anemia (12.6 g/dL) and thrombocytopenia
(57,000). Arterial Blood Gases (ABGs) demonstrated a partially
compensated metabolic acidosis with adequate oxygenation.
Plain chest radiography identified infiltrates in the right lung field
suggestive of pneumonia. The newborn was placed on ampicillin
and gentamycin for possible sepsis, however COVID-19 infection
was considered likely.
The newborn’s work-of-breathing steadily increased,
eventually triggering treatment with a Vayu bCPAP system.
Initial bCPAP settings included an FiO2 of 30% and pressure of
five cmH2O. An electrostatic filter (Great Group Medical Vf-2160
series) with viral filtration efficiency of 99.99% was positioned
immediately prior to the pressure generator in the expiratory limb
of the respiratory circuit.
After being placed on a Vayu bCPAP system, the infant’s
respiratory distress significantly improved. An RT-COVID-19
PCR test performed at 48 hours of life was positive. Additional
laboratory tests at 48 hours included elevated procalcitonin (1.23
ng/mL) and C-reactive protein (3.17 mg/L) levels and a normal
ABG. Upon testing positive for COVID the newborn was moved to
an isolation area and infection control measures such as strict use
of PPE were employed.
On the fourth day of hospitalization, abdominal distention,
and coffee ground oro-gastric tube (OGT) output were noted.
Tachypnea and retractions continued to improve. Abdominal
radiographs demonstrated an ileus. Necrotizing enterocolitis was
suspected, the infant was started on total parenteral nutrition
(TPN) and antibiotics were shifted to Ceftazidime, Amikacin and
Abdominal distention and all signs of respiratory distress
resolved by day seven of life. The neonate was successfully
weaned from the Vayu bCPAP system to room air and oral tube
feeding was initiated.
By the tenth day of hospitalization a repeat COVID RT-PCR was
negative and ABG’s were normal. The newborn fully recovered. As
per hospital protocol during the COVID-19 surge, weekly COVID
RT-PCR tests were administered to all healthcare workers and
all of healthcare personnel that cared for the newborn tested
The infant was discharged on the fourteenth day of life.
In summary, we described the use of a novel bCPAP system
engineered with a downstream filter to treat a COVID-19 positive
neonate in respiratory distress. The filter was positioned on the
expiratory limb of the breathing circuit to limit the nosocomial
spread of infection to other patients and healthcare workers
We speculate that there are several reasons this case is without
precedent. First, there have been reports that actively heated and
humidified CPAP systems equipped with expiratory filters may
cause instability in the system’s delivered pressure and impose an
increase in the work of breathing . These effects are far more
detrimental for infants than for adults or older children who have
more developed respiratory systems [22-25]. Additionally, before
the pandemic, infection control was less of a priority and this, in
concert with the dearth of research on the effect of expiratory
CPAP filters on infants, may have inhibited the use of CPAP system
compatible filters when treating neonates .
Findings from our lab are consistent with Davis et al’s conclusion that expiratory filters positioned before a pressure generator significantly increase the delivered pressures in actively
heated bCPAP systems . However, we found that the delivered
pressure in a Vayu bCPAP system did not significantly change
when an expiratory filter (Great Group Medical Vf-2160 series)
was positioned before the pressure generator. When set to 8 cm
H2O of pressure, the mean pressures delivered by a Vayu system
after 24 hours with a filter and without were 8.00 ± 0.05 cm H220
and 7.95 ± 0.03 cm H2O respectively (Figure 2). These results
are consistent with our lab’s previously reported findings that
the Vayu bCPAP system’s delivered pressure remains stable and
accurate when used with an expiratory filter .
The varying effects of expiratory filters on delivered pressures
across different bCPAP systems are likely attributed to the presence
or absence of condensate in the exhalation limbs and within
the expiratory filters of bCPAP systems. We observed persistent
condensate formation in the expiratory limb of a Fisher & Paykal
bCPAP device (which had an increase in delivered pressures), but
no condensate formation in a Vayu bCPAP system (which had no
change in delivered pressure) over a 24-hour test period. Further
investigation identified that the condensation was caused by the
heater in the Fisher Paykel bCPAP circuit. In contrast, the Vayu
bCPAP system is innovative in that it uses the heat from a warmer
or incubator to provide an ideal mixed gas temperature. Our
findings were similar to Davis et al who reported that the delivered
pressure is more stable in a Fisher & Paykel bCPAP device when an
expiratory filter is placed after the pressure generator rather than
before. When an expiratory filter is placed before the pressure
generator it can become saturated with water . Our findings
are consistent with Donaldsson et al’s investigation that reported
no significant changes in delivered pressures of bCPAP devices in
a non-humidified environment .
The Vayu bCPAP system has the potential to mitigate virus
transmission from infants in NICUs with COVID-19 and other
respiratory infections such as respiratory syncytial virus (RSV)
. Since newborns are obligate nose breathers and properly
fitted bCPAP devices are essentially closed systems, the expiratory
filter on a Vayu bCPAP system may help protect healthcare
workers and others that come in contact with infected newborns
by channeling expiratory gases through the expiratory filter .
Despite decades of infection control quality improvement efforts,
respiratory transmission rates remain high for hospitalized
infants who come in contact with RSV infected patients .
Subsequently, nosocomial respiratory viral infections remain a
leading cause of morbidity and prolonged hospital stay among
preterm newborns [31,32]. The burden of respiratory nosocomial
infections is even higher in resource constrained settings where
NICU outbreaks are more frequent and mortality rates greater .
In bCPAP systems without condensation, expiratory filters
appear to have little effect on pressure delivery and are a relatively
affordable modification for thwarting nosocomial infections
compared to building isolation rooms or hiring specialized staff.
Furthermore, as of January 2022 the NICU at Ilocos Regional
Training Medical Center routinely uses novel expiratory filters
that have reusable filter housings. The filter disks of these novel
filters can be replaced every 24 hours at a cost of $0.18 USD.
While expiratory filters for neonates are typically single use and
designed for mechanical ventilators, this case and the development
of reusable filters may help pave the way for exploring use of
expiratory filters with neonatal CPAP systems more broadly [2,33-
Neonatal bCPAP device manufacturers should strongly
consider engineering and testing modifications that allow
incorporation of downstream filters similar to the Vayu bCPAP
system in order to better prepare NICUs worldwide for both the
current and future pandemics.
This case reports is in compliance with the guidelines for
human studies accordance with the World Medical Association
Declaration of Helsinki.
Study approval statement: the Institutional Review Board
of Ilocos Training & Regional Medical Center does not require
approval for case reports.
Consent to publish statement: Informed consent was obtained
from the parents of the patient for publication of the details of
their medical case and any accompanying images. Information
that could possibly identify the patient in this case report were