High-Flow Nasal Cannula Use Outside of the ICU Setting

We conducted a survey that was distributed to the Pediatric Research in Inpatient Settings (PRIS) Network site leads. The PRIS Network consists of 114 sites representing 45 US states and 2 Canadian provinces. Data were collected by using Research Electronic Data Capture. Each PRIS site has a designated representative, and the survey required reporting of the institutions’ name to ensure that multiple surveys were not completed from a single institution. The survey was reviewed by the PRIS Steering Committee members and piloted with physicians from several institutions. The survey consisted of 10 initial questions related to institutional demographics. We encouraged the PRIS representative to engage with other colleagues at their site if the representative was unable to complete any portion of the survey. Survey domains included HFNC practice information, such as program characteristics, indications for use, flow and oxygen rate parameters, presence of protocols, and staffing. After initial distribution, 3 monthly reminder e-mails were sent. The survey was deemed exempt by the institutional review board.

Bivariable analyses were used to identify variables more often present in sites that provide HFNC therapy on the wards. For institutions that used HFNC on the wards, descriptive data were compared by hospital type. Respondents reported their hospital types as either freestanding children’s hospitals (CHs), CHs within adult hospitals, or community hospitals. For the purposes of hospital type comparison, we designated freestanding CHs and CHs within adult hospitals as CH sites. We chose to group in this manner because these two settings share a similar care model and resources, such as on-site ICUs, pediatric-trained ancillary staff and services, and trainee presence. Community hospitals were designated non-CH sites. P values were calculated by using Fischer’s exact test and the χ² test. Statistical analyses were completed by using R software.

Of the 114 PRIS sites contacted, our survey was completed by the designated representative at 77 sites, resulting in a survey response rate of 68%. Freestanding CHs and CHs within adult hospitals made up the majority of responding sites, with 42% and 39% responses, respectively. Non-CH sites accounted for approximately one-fifth of all respondents. Most responding sites were associated with a university center. The 77 sites represented 5 geographic regions in the United States (97%) and Canada (3%): the Midwest (29.9%), Northeast (22.1%), Southeast (22.1%), mid-Atlantic (11.7%), and West (11.7%) regions. The majority of responding sites had an on-site PICU (90%), whereas 66% reported an on-site NICU that accepts patients from the ED and/or pediatric ward. Slightly more than one-third of sites had a step-down unit (36%). We used the term pediatric ward to describe an acute care unit specializing in the care of children exclusively, with more specific requirements based on a particular hospital’s capacity. A step-down unit, also referred to as an intermediate care unit, is a unit for patients who require services beyond the capabilities of the pediatric ward but with less severity of illness than those patients requiring intensive care.^26,27  We considered these as two distinct care settings within a hospital.

Thirty-seven of the 77 sites (48%) used HFNC therapy on the pediatric ward. Of those sites using HFNC on the wards, the majority were freestanding CHs (46%) and 27% were CHs within adult hospitals. Non-CH sites made up 27%. Data for comparing the practices of ward HFNC use by setting type are summarized in Table 1. All CH sites that provided HFNC on the ward had an on-site ICU, compared with 60% of non-CH sites (P = .003). Comparative data of responding sites are summarized in Table 2.

Implementing HFNC in the pediatric ward setting was an interdisciplinary process most often initiated by the pediatric hospital medicine department (78%). This was followed by respiratory therapy (RT) (46%) and critical care medicine (35%) and typically included leadership in the ED, nursing, and hospital administration. Seventy percent of sites that used HFNC on the ward had been doing so for <5 years. All sites had pediatric hospitalists staffing the ward. In decreasing order, other provider types that staffed the wards were pediatric residents (76%), family medicine residents (65%), general pediatricians (41%), and nurse practitioners or physician assistants (19%).

All sites reported using HFNC for patients with bronchiolitis. Pneumonia (51%) and asthma (43%) were other indications for HFNC use. EDs, ICUs, and wards were the most common settings where HFNC was initiated. CH sites initiated HFNC more often in the ED and ICU (P = .01) compared with non-CH sites. There were no statistically significant differences found between the sites that employed ward use of HFNC and those that did not in terms of hospital type, ICU presence, or university affiliation.

Seventy-six percent of sites used locally developed protocols to guide HFNC use. CH sites used local protocols more often than non-CH sites (85% and 50%, respectively); this difference was not statistically significant. Protocols addressed HFNC initiation (68%), ongoing assessment (68%), and, less often, weaning (57%). We did not query protocol exclusion criteria. CH sites were significantly more likely to have order sets (P = .02), reassessment requirements (P = .05), and weaning protocols (P = .01) (Table 1).

Variability existed regarding parameters of HFNC use. Flow rate at initiation was determined by several factors, including weight, age, protocol, or a combination of these factors. Thirty-eight percent of sites that provided HFNC on the ward determined initial flow rate on a case-by-case basis. Similarly, maximum flow rates were determined by these same factors, with a reported range from 6 to 15 L/minute. Of the 19 sites reporting a maximum flow rate regardless of age or patient weight, 63% reported setting a maximum flow rate of ≤8 L/minute on the wards (Table 3). Forty-one percent of sites defined a standard fraction of inspired oxygen at initiation ranging from 40% to 70%. Of those reporting weaning parameters, 65% of sites weaned from HFNC to standard nasal cannula and 22% of sites weaned from HFNC directly to room air.

Institutional HFNC protocols guided provider care at many levels. The majority of sites required RTs to provide patient assessments (62%). Nursing and physician assessment frequency was established in the protocols, although not as often (46% and 19%, respectively). Approximately one-third of sites had a defined nurse/patient staffing ratio for patients on HFNC. For sites that defined a specific staffing ratio, 85% required a ratio of 3:1 or lower to care for these patients.

Sites used clinical scores for reassessment during HFNC, most commonly a bronchiolitis score (62%) or Pediatric Early Warning Score (49%). Eight percent of sites did not use score-based tools for patient assessment. At initiation of HFNC, few sites required a chest radiograph (3%) or arterial blood gas (5%), whereas establishing intravenous access was a more common requirement (22%). Nearly three-quarters of sites that provided HFNC on the pediatric ward determined diagnostic tests and imaging on a case-by-case basis.

There was also great variability in feeding practices with patients on HFNC. Among those with defined feeding practices while on HFNC, there was a range from oral feeding to maintaining patients by nil per os (NPO) orders. Of the sites reporting feeding practices, 8% permitted oral feeding, whereas 3% gave patients NPO orders. The remainder used various enteral methods, including nasogastric or nasoduodenal feeds, or determined feeding practices on the basis of clinical judgment.

Fifty-nine percent of survey respondents who provided HFNC on the ward tracked outcomes, such as ICU transfer rate, LOS, and intubation rate. Less than 20% of sites reported measuring hospital charges and readmission rates. Less than 10% of sites monitored complications (such as pneumothorax), hospital throughput metrics, and patient satisfaction. Forty-one percent of sites were not currently tracking any outcomes related to HFNC use.

To our knowledge, this is the first study to describe HFNC practice patterns in the pediatric ward setting in North America. Approximately half of survey sites reported HFNC use on the wards. The most common indication for ward HFNC use was the management of acute respiratory distress due to bronchiolitis. Asthma and pneumonia were other less common indications for ward use of HFNC. Although CH sites are significantly more likely to have order sets and initiation and weaning protocols, variation exists about flow amount, oxygen use, feeding practices, and staffing ratios. In addition, of the factors evaluated, there are no apparent factors present in the sites that allow for ward use of HFNC that distinguish them from sites that do not.

Concerns about clinical decompensation and how to best identify which patients might fail HFNC therapy are frequently cited barriers to implementing HFNC on wards.^27,28  However, it should be noted that none of the studies of ward-based protocols revealed increased intubation rates or increased decompensation on the ward.^20–22  Several studies have revealed that response to HFNC is typically observed within 60 to 90 minutes of initiation.^{9,26,27,29–32}  Nonresponders might be identified within the first hour of HFNC therapy by monitoring key vital signs. Experts recommend that units using HFNC in the ward setting have the ability to provide continuous cardiorespiratory monitoring and have resources and staff to support rapid intubation and ventilatory support if required.^16,29  Our survey respondents cited the use of a clinical score to determine HFNC response and ongoing monitoring. Frequent reassessment from RT and nursing was also common in most protocols. Although there was no consensus on patient-to-nurse ratios or frequency of physician-level patient assessments, most sites reported modified nursing ratios for these patients. Having clearly defined protocols for assessment, staffing, and escalation is important for the safety of ward HFNC use.

Our data suggested a lack of standardized practice with HFNC flow rates. Most sites set flow maximums of 6 to 8 L/minute for patients receiving HFNC on the wards. This is much lower than that found in studies outside the United States, in which 1 to 2 L/kg per minute were used on pediatric wards.²²  In a prospective trial, Weiler et al³³  evaluated the effect of various weight-based flow rates on efforts of breathing in children <3 years of age. They found that breathing efforts decreased as flow rates increased, with the largest decrease at a flow rate of 2 L/kg per minute in infants, suggesting that lower flow rates may not be physiologically therapeutic.³³  Mayfield et al⁹  evaluated the response to HFNC with HFNC flow rates of 2 L/kg per minute up to a maximum of 10 L in patients <12 months old and reported no adverse events. These results provide evidence that a weight-based flow rate, particularly in younger children, may be a way to standardize HFNC flow delivery. This concept remains controversial, and North American centers appear to be reluctant to use higher flow rates.

Feeding practices were among the most variable aspects of patient care for those on HFNC, with 76% of respondents determining this on a case-by-case basis. In ICU settings, it has been reported that the use of HFNC has been associated with delayed enteral feeding.²⁷  However, studies indicate that adverse events, such as aspiration and worsening respiratory distress, are infrequent in infants with bronchiolitis admitted to the ICU receiving HFNC therapy, supporting the idea that routinely keeping these patients under NPO orders may be unnecessary.^27,32 

Another obstacle to implementation of HFNC on the pediatric ward is avoiding overuse both in terms of duration of therapy and overuse of HFNC. Riese et al²¹  found that implementation of an HFNC ward protocol increased use of the therapy. Fifty-seven percent of surveyed sites reported providing guidance for weaning HFNC in their site’s protocol. Most institutions weaned from HFNC to low-flow nasal cannula rather than directly to room air. Further data to clarify best HFNC weaning practices could be used to avoid prolonged use of the therapy.

The most commonly measured outcomes were ICU transfer rate, LOS, and intubation rate. In a retrospective cohort study of patients with bronchiolitis, use of HFNC resulted in a 14% absolute risk reduction in the intubation rate and a decrease in ICU LOS.³³  Riese et al²¹  published data reviewing the effects of their local institutional ward HFNC protocol on the care of patients with bronchiolitis <24 months of age. They found no change in the ICU transfer rate or LOS after implementation of their protocol.²¹  With many sites not tracking outcomes related to ward use of HFNC, there continues to be a lack of outcomes-related evidence to the use of HFNC in the management of respiratory distress.

Our study has several limitations. Because the survey was distributed by using the PRIS Network, a single response represents institutional practice of each site. Survey responses were not validated because the authors did not review site protocols. The questions may have had a range of interpretation, and there were no other criteria, aside from serving as the designated PRIS representative, required for respondents to complete the survey. Potential misinterpretation was mitigated with pilot testing of the survey before distribution. There is a possibility that our data set underestimates the use of HFNC in the pediatric ward setting because we did not include sites outside the PRIS Network. Community hospitals with pediatric units may have different motivations to provide HFNC to prevent interhospital transfers to tertiary care centers and help provide care closer to home for patients and families.

However, despite these limitations, we believe these data represent a useful summary of current HFNC inpatient pediatric practice within this research network. Exploring why certain institutions choose to use HFNC on the wards may be an area of further study. Tertiary care centers with high PICU and NICU census may explore options to provide HFNC in the ward or step-down units to effectively operationalize their hospital patient flow.

This is the first survey to gather data on HFNC practice patterns outside the ICU in North America. Nearly half of the survey respondents used HFNC on the pediatric wards. All sites used HFNC on wards for management of acute respiratory distress due to bronchiolitis, with some sites also using HFNC in patients with asthma and pneumonia. Although CH sites are significantly more likely to have HFNC orders sets and protocols, variability exists regarding flow rates, initiation, weaning, staffing, and feeding practices. The majority of sites reported using 6 to 8 L/minute as a maximum flow rate. Our study findings suggest that HFNC is being used by pediatric hospitalists in the management of acute respiratory conditions, but the use remains variable and is based on local consensus.

Although emerging literature is beginning to address some questions related to HFNC practice, there are still many unanswered questions related to HFNC use. Providing HFNC outside the ICU may improve the value of inpatient care of respiratory conditions and may improve resource use by preventing unnecessary ICU admission and other ineffective therapies. Future studies should focus on the patient outcome measures to generate evidence for appropriate HFNC use and development of national guidelines.

We thank the PRIS Steering Committee for their input on this study. We also thank Dr Vineeta Mittal for her guidance through the early stages of project development and initial manuscript review.

CH

children’s hospital

ED

emergency department

HFNC

high-flow nasal cannula

LOS

length of stay

NPO

nil per os

PRIS

Pediatric Research in Inpatient Settings

RT

respiratory therapy