Continuous positive airway pressure (CPAP) is the application of pressure to maintain airway patency, prevent atelectasis, improve oxygenation, and avoid airway trauma imposed by intubation; nasal continuous positive airway pressure (NCPAP) is used for delivering CPAP in neonates.1 Various products are used to deliver NCPAP; while features of the various designs differ in some areas, all have a heated and humidified blended gas source, a pressure-generating apparatus, along with a circuit and nasal interphase. Binasal prongs are the most common method of gas delivery. Due to unique anatomical and physiological characteristics of the columella area in neonates, binasal prong use can result in hyperemia, edema, ulceration, and complete columellar necrosis.2 Proposed mechanisms for pressure injury (PI) include interface pressure, friction, or shearing forces when the device is applied to the nose, and creation of a warm and humid microclimate surrounding the affected area. The global reported incidence of nasal trauma ranges from 20% to 60%.3–5
Researchers have compared the rates of injury with different CPAP systems and found differences based on design.3–9 We also found one study that reported fewer complications with a nasal cannula when compared to binasal prongs or masks.10 Researchers and clinicians have also questioned whether dressings can prevent PIs.11 Guidelines from the National Pressure Ulcer Advisory Panel (NPUAP), European Pressure Ulcer Advisory Panel, and Pan Pacific Pressure Injury Alliance recommend use of barrier products to offload pressure and reduce friction or shearing forces in all patients at risk for PI.12 Findings from multiple studies suggest that barrier dressings are effective for prevention of sacral PI, but less is known about their efficacy in prevention of medical device-related pressure injury (MDRPI) in infants managed with NCPAP.13–15 The objectives of this study were to measure the incidence and severity of nasal septum injury in premature infants receiving noninvasive ventilation (NIV) via a nasal cannula and to evaluate the efficacy of polyvinyl chloride foam in reducing these MDRPIs in neonates managed by NCPAP.
Data were collected via review of medical records. Our study setting was a single-center, level 4, regional neonatal intensive care unit (NICU); this unit is part of a 200-bed freestanding children's hospital located in the Northeastern United States. The 57-bed NICU cares for approximately 2500 neonates annually, including 200 to 300 newborns weighing less than 1500 g. Our NICU also serves neonates with the most complex conditions; we offer extracorporeal membrane oxygenation, therapeutic hypothermia, and provide innovative cardiac, neurologic, and gastrointestinal surgery. The medical records of all premature infants under 286/7 weeks' gestational age requiring NCPAP during their admission were identified and reviewed. We limited our review to neonates managed by a minimum of 24 hours of NCPAP. Exclusion criteria were congenital nasal deformities and neonates who were older than 286/7 weeks' gestational age when started on NCPAP. The study protocol was reviewed and approved by the Cohen Children's Medical Center of New York Institutional Review Board (approval number HS16-013C).
Continuous positive airway pressure was delivered via a nasal cannula. The NCPAP used in our facility includes a short, binasal prong cannula and a small diameter, lengthy connecting tube attached to a ventilator circuit capable of transmitting positive pressure. This system is approved by the US FDA as an oxygen-delivering nasal cannula. The thin-walled nasal cannula we selected for use (RAM Cannula Neotech, Valencia, California) is a class 1 medical device that comes in 3 sizes; sizing is based on the patient's weight. We have found that this system is lighter than traditional NIV apparatus. Our clinical experience also suggests that the system is easy to maintain, which encourages parental bonding. Theoretical advantages of the system are its construction using a soft material and thin-walled prongs with a relatively large inner diameter prong resulting in lower resistance. The thin-walled cannula produces 60% to 80% occlusion of the nares that facilitates exhaled gas flow and minimizes the chances of carbon dioxide accumulation.
Based on this initial evaluation, the manufacture suggests that users should not develop a nasal injury while using the thin-walled cannula.17 This recommendation is based on concerns that use of a foam dressing may create a 30% loss of occlusion between the prong and nostrils; this proportional loss was based on their initial product evaluation.17 Nzegwu and colleagues16 evaluated this thin-walled cannula we used while delivering different modes of NIV. They also reported no breakdown of the nasal skin, but identification of PIs of the nasal skin was not a stated aim of their study.
Despite these recommendations, we elected to use a dressing to reduce the risk of nasal injury when the thin-walled cannula was introduced into our facility. The polyvinyl foam we selected was a precut soft foam placed on the prongs (Neoseal, Neotech, Valencia, California). Specifically, the adhesive surface is placed against the prongs in order to reduce the risk of MDRPI of the nasal skin by redistributing tissue interface pressures, friction, and potential shearing forces created when the NCPAP system is in active use (Figure 1).
The thin-walled cannula was set up according to manufacturer instructions and the size was chosen based on the patient's weight. The tubing was anchored by hydrocolloid holders on the cheeks. Nurses made sure that the thin-walled nasal cannula adhered symmetrically on both sides in order to avoid impingement of the ears or back of the head. Prongs were chosen to ensure no more than 30% leak in order to ensure passive carbon dioxide outflow, since this system does not have the expiratory limb characteristic of class 2 devices. Thus, the only difference between our setup versus the manufacturer's recommendations for use was the addition of the foam dressing applied to the thin-walled nasal prongs as described earlier (Figure 1). Respiratory therapists and nurses ensured that the foam barrier did not occlude the nares via frequent visual assessment (at least every 3 hours) and by ensuring that adhesive side was consistently attached to prongs and not the neonate's skin. Standard nursing care was provided; specifically, the nasal skin was inspected every 3 hours for erythema, breakdown, and edema by lifting and repositioning the nasal prongs. In addition, a nonalcoholic liquid polymer skin protectant (Cavilon No Sting Barrier Film, 3M, St Paul, Minnesota) was placed under the skin/device interfaces once daily. Normal saline wipes were used to clean skin as needed; skin dryness was assured before placing the thin-walled nasal cannula.
Medical records were reviewed during 3 periods from April 2014 until September 2016. I extracted all data from medical records using a standardized form developed for purposes of this study. Demographic and pertinent clinical data collected include gestational age, birth weight, CPAP application on admission, incidence of sepsis, patent ductus arteriosus, necrotizing enterocolitis, and length of stay as a surrogate of morbidity and actual mortality in each group. All data were deidentified upon entry into the standardized, computerized form.
Study Period 1
The thin-walled cannula described earlier was introduced to our NICU in April 2014. Prior to introduction of the specialized cannula, we used a standard NCPAP cannula and a polyvinyl foam as offloading barrier for CPAP interphases. We also applied a foam dressing on the prongs of the cannula in order to prevent PI of the nasal skin. Upon switching to the specialized, thin-walled cannula, we continued use of polyvinyl foam as a barrier dressing.
Study Period 2
Despite skepticism among clinicians at my facility, we decided to implement the manufacturer recommendation that the specialized walled nasal cannula could be used without the addition of a foam barrier dressing as an additional PI preventive intervention. Before entering into this period of care, all neonatal staff (RNs and respiratory therapy staff) completed mandatory reeducation on MDRPI, concentrating on their prevention in patients using respiratory devices such as NCPAP. Risk factors for nasal injuries were reviewed, along with preventive measures including evaluation, repositioning, and essential skin care. Procedures for proper sizing and placement of the thin-walled nasal cannula based on the manufacturer's recommendations were reinforced. An RN or respiratory therapist evaluated each patient's columellar condition every 3 hours. We ultimately elected to terminate period 2 after only 3 months because of the high incidence and severity of nasal injuries.
Study Period 3
Based on our experiences during study period 2, we went back to managing patients with the thin-walled nasal cannula and foam dressing during study period 3. No new technologies or clinical practice guidelines were introduced in the unit during the study time.
Assessment of Skin and Mucosa of Nose
During all 3 study periods, infants were monitored once a shift for the development of nasal injury until weaned off CPAP. Trained members of our neonatal wound care service, including a wound certified physician, clinical nurse educators, and trained neonatal nurses, evaluated, confirmed the presence of, graded, and treated nasal injuries during all 3 periods. All nasal injuries were followed to resolution or in the case of columellar necrosis, 1-month past discharge in the neonatal clinic. Nasal injuries may involve skin and mucosa, rendering it difficult to assign a single NPUAP stage. We classified skin damage as mild (erythema or stage 1), moderate (worsening erythema and partial-thickness injury or stage 2), and severe (full-thickness—stage 3 to columellar necrosis—stage 4) categories attempting to follow NPUAP staging (Figure 2).
All analyses were carried out using SAS Version 9.4 (SAS Institute Inc, Cary, North Carolina). We used the χ2 test to evaluate differences in dichotomous variables and completed analysis of variance plus Bonferroni post hoc testing for continuous variables.
Between April 2014 and September 2016, 3455 newborns were admitted to our unit. Based on inclusion and exclusion criteria described earlier, we reviewed and extracted data from the medical records of 235 neonates who met these criteria. Data were extracted from the medical records of 80 patients during study period 1, 27 records were reviewed during period 2, and 128 were reviewed during period 3. There were no statistically significant differences in gestational age, birth weight, or other baseline characteristics between 3 groups (the t test was used to assess differences in gestational age between 3 groups). Analysis also revealed no statistically significant differences in the incidence of any other short-term outcome including necrotizing enterocolitis, patent ductus arteriosus, sepsis, chronic lung disease, oxygen use days, hospital length of stay, or mortality rates between cohorts. Table 1 shows demographic and clinical characteristics of the study population. Analysis of variance was used to evaluate the differences between PI rates and severity.
Pressure Injury Occurrences
During study period 1, we reviewed the records of 80 patients and identified 6 PIs of the nasal skin, reflecting an occurrence rate of 7.5%. Three were stage 1 and 3 were stage 2. We reviewed the medical records of 27 patients during study period 2. We identified 13 PIs; 3 were stage 1, 5 were stage 2, and 3 were stage 3. In addition, we identified 2 cases of columella necrosis, reflecting a PI rate of 48%. During study period 3, we reviewed the medical records of 128 patients, reflecting a PI rate of 1.5%. We identified 2 PIs, 1 was stage 1 and 1 was stage 2 (Table 2). Both PIs resolved within 2 to 4 days.
When the barrier foam dressing was used during study periods 1 and 3, we observed no full-thickness PI or cases of columella necrosis. In contrast, the PI rate was 6-fold higher during study period 2, and 40% of the injuries were stage 3 or reflective of columella necrosis. A statistically significant difference in the rate of PI was observed comparing periods 1 and 3 (barrier dressing used) when compared to period 2 (no barrier dressing, P < .001).
Findings from this retrospective study suggest that use of a specialized, thin-walled nasal cannula resulted in a 6-fold higher rate of nasal PI occurrences when compared to its use in combination with a foam barrier dressing. Based on this finding, I assert that use of a foam barrier dressing is effective for prevention of PI and columellar necrosis in infants less than 28 weeks of gestation. Based on a review of the literature, I believe this is the first study to specifically evaluate occurrences and severity of PI associated with this walled nasal cannula in preterm neonates. My results are consistent with overall data on NIV interphases and risk of MDRPI in neonates in general.3,4,7,8
Noninvasive ventilator-delivered CPAP is generally delivered via binasal prongs. Adverse side effects attributed to this life-sustaining therapy include abdominal distention, feeding intolerance, pneumothorax, and nasal injury. The unique anatomy of the neonatal columella area, the need to precisely fit the cannula to deliver distending pressure, and the limited options for repositioning these devices contribute to ongoing interface pressure placed on the nares and septum during NCPAP.18,19 Neonatal skin immaturity has been extensively studied and evidence demonstrates that the stratum corneum is particularly thin in preterm infants younger than 23 to 24 weeks.4 The stratum corneum is a 1- to 2-cell layer around 26 weeks, and it is not deemed mature until at least 33 weeks.7,8 We have found that even then the texture differs drastically from older babies. Intrinsic risk factors such as age, poor nutrition, an underdeveloped immune system, hemodynamic instability, and sepsis increase inflammatory mediators, vasodilatation, and edema, rendering the neonate vulnerable to MDRPI.19 The most common area injured in neonates as a result of medical device is the nose.19 The columellar area of the neonate houses the bony maxillary spine, which is surrounded by sparse vessels and little subcutaneous and dermal tissue needed to offload the pressure (tissue load) created when a nasal cannula is placed in the nares.18 In addition, nasal prongs placed around columella must be securely placed on the face of a 700-g baby in order to prevent them from moving and losing their effectiveness in the warm and humidified environment created in the isolate.
The tissue load from this interface pressure may lead to deformation of skin layers, poor blood flow, ischemia, inflammation, and cell death.2 Injured cells undergo reperfusion injury within few hours from original insult, which may worsen the damage in the next few days even as circulation returns. Lack of robust stratum corneum, thin dermis, constant warmth, and humidity delivered by CPAP apparatus place nasal skin at high risk for injury.4 Research also indicates that a warm, humid microclimate places already poorly perfused skin at a disadvantage (every 1°C increases oxygen consumption by 10%). These conditions also increase metabolic demands of local subcutaneous tissues and weaken the intercellular cytoskeleton's connections, thus reducing the tolerance for applied pressure.2
In addition to the need for secure placement in a warm and humid environment, neonates are often placed prone, thus increasing friction between the nasal skin and prongs. Clinical experience in this area strongly suggests that cutaneous sensations are often diminished in the tiniest and sickest babies as exemplified by the infrequency of crying among sick, preterm neonates. Even when sensations are not impaired, clinical experience demonstrates that pain is particularly difficult to assess in the premature neonate. Finally, mobility is often limited in these vulnerable infants when special developmental positioners are used that limit body and head movement.
No robust guidance for management and prevention of neonatal nasal skin injury exists. According to NPUAP, anyone using medical equipment should be deemed as a high-risk patient.15 Recommended strategies to reduce risk include correct fit and positioning, frequent assessments, keeping skin dry and clean, applying nonirritant barrier (dressings that do not gel are recommended to avoid skin stripping or maceration), and vigilance concerning the harness and ventilator circuit position.12 Researchers advocate frequent assessments, developmental positioning, nursing education, and barriers as preventive methods. Despite the importance of nursing vigilance and expertise, studies do not support its efficacy in fully eliminating PI.7,20,21 Nevertheless, Weng and colleagues22 reported a decreased rate of PI when neonates receiving NCPAP were managed with hydrocolloid and film dressings versus those managed without dressings.22 Hsu and coworkers23 advised caution when using hydrocolloid, as epidermal stripping was prevalent during dressing changes, as well as sticky residue especially in humidified environment. They reported the lowest injury rate when using a soft silicone, followed by a hydrocolloid, followed by no barrier. Imbulana and associates24 reported similar findings. In addition, they reported that while hydrocolloid dressings decrease PI injuries, they were difficult to manage in humidified isolettes and prevented visualization of underlying skin.24 Gunlemez and colleagues25 described success in application of a silicone gel sheet at the nasal surface to alleviate direct pressure.
Other researchers have reported success when applying a polyurethane foam for prevention of PI in other anatomic areas. Cohen and colleagues26 found that a polyurethane foam dressing reduced the rate of facial tissue deformations and stresses under an NIV mask. We have used absorbent, atraumatic polyurethane foam (Mepilex Lite foam, Molnlycke Health Care, Norcross, Georgia) but had no success when applying the dressing to the nasal cannula of infants undergoing CPAP due to poor adhesion, frequent need to reposition, and difficulty in cutting the dressing to the appropriate size.
Our experience suggests that the foam barrier we chose has several advantages when used for prevention of nasal tissue injury in infants managed with NCPAP. By placing the foam barrier directly on the prongs some pressure was redistributed while reducing the tissue deformation created by the prongs. Our experience also suggests that this arrangement reduces friction between the nasal skin and cannula, especially when the neonate is placed in a prone position. We further observed that the foam dressing absorbed and promoted evaporation of warm, humid air without changing its relative pliability; potentially alleviating some of the negative effects of the warm, humid microclimate present when these devices are used in neonates. While frequent assessments were completed to ensure that skin was dry and intact, we found that most foam barrier dressings required changing every 2 to 3 days. We also found that placing the adhesive surface of the foam dressing to the prongs prevented medical adhesive-related skin injury while preserving the necessary seal needed to deliver effective CPAP.
Figure 3 illustrates the control chart used in quality improvement projects to assess whether a given process is stable and identify the impact of an effort by looking for evidence of special cause variation. Data from this figure also support the conclusion that addition of the barrier reduced PI occurrences.
Data were collected in a single unit. In addition, the data collection period for study period 2 was shorter than periods 1 and 3. We planned to collect data over a longer period of time resulting in a larger cohort for comparison, but the number and severity of PIs prompted us to discontinue use of the these walled nasal prongs without concurrent use of the foam dressings after 12 weeks. Future studies with a larger patient sample are recommended.
Pressure injuries are a key clinical indicator of the standard and effectiveness of care, but evidence supporting prevention of neonatal MDRPI associated with NCPAP is sparse. In an effort to support NIV, new respiratory devices were introduced in our facility in 2014. While we found that the specialized, thin-walled cannula proved lighter and easier to use than prior designs, we found it resulted in a relatively high prevalence of MDRPI and necrosis of the nasal columella when used without foam dressings applied to the cannula. Contrary to the manufacture's recommendations, we also observed that use of a foam barrier dressing prevented MDRPI and columella necrosis without compromising the intended effect of the device. If no barrier is used, constant vigilance of the nasal skin is recommended.
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