Emergency department course of patients with asthma receiving initial emergency medical services care—Perspectives From the National Hospital Ambulatory Medical Care Survey

Abstract

Objective

Although 911 calls for acute shortness of breath are common, the role of emergency medical services (EMS) in acute asthma care is unclear. We sought to characterize the demographics, course, and outcomes of adult emergency department (ED) patients with asthma in the United States receiving initial EMS care.

Methods

We analyzed data from the 2016–2019 National Hospital Ambulatory Medical Care Survey (NHAMCS). We included patients aged ≥18 years with an ED visit diagnosis of asthma, stratifying the cases according to initial EMS care. Accounting for the survey design of NHAMCS, we generated nationalized estimates of the number of EMS and non-EMS asthma visits. Using logistic regression, we determined the associations between initial EMS care and patient demographics (age, sex, race, and insurance type), ED course (initial vital signs, triage category, testing, medications), and outcomes (hospital admission, ED length of stay).

Results

Of 435 million adult ED visits during 2016–2019, there were ≈5.3 million related to asthma (1.3 million annually, 1.2%; 95% confidence interval [CI], 1.1%–1.4%). A total of 602,569 (150,642 annually, 11.3%; 95% CI, 8.6%–14.8%) ED patients with asthma received initial EMS care. Compared with non-EMS asthma patients, EMS asthma patients were more likely to present with an “urgent” ED triage category (odds ratio [OR], 22.2; 95% CI, 6.6–74.9) and to undergo laboratory (OR, 2.78; 95% CI, 1.41–5.46) or imaging tests (OR, 2.42; 95% CI, 1.21–4.83). ED patients with asthma receiving initial EMS care were almost 3 times more likely to be admitted to the hospital (OR, 2.81; 95% CI, 1.27–6.25). There were no differences in demographics, ED use of β-agonists or corticosteroids, or ED length of stay between EMS and non-EMS asthma patients.

Conclusions

Approximately 1 in 10 adult ED patients with asthma receive initial care by EMS. EMS asthma patients present to the ED with higher acuity, undergo more diagnostic testing in the ED, and are more likely to be admitted. Although limited in information regarding the prehospital course, these findings highlight the more severe illness of asthma patients transported by EMS and underscore the importance of EMS in emergency asthma care.

INTRODUCTION Background

Acute asthma is a major public health problem, and its treatment is time sensitive. The prevalence of acute asthma in the United States is 7.8%, representing >25 million patients and >1.8 million annual emergency department (ED) visits.¹ Almost half of adults with a history of asthma report an exacerbation in the previous year, and 10% have visited the ED.² Prompt treatment is essential to optimize asthma outcomes.^3–5 Time delays in acute asthma care are associated with increased disease severity and increased need for hospitalization.⁶

Importance

Prehospital emergency medical services (EMS) offers one of the fastest ways to provide acute asthma care. Essential acute asthma interventions performed by EMS may include support of oxygenation and ventilation and administration of inhaled or intravenous medications. The role of EMS in the care of children with acute asthma has been examined in terms of demographics, treatments initiated, and impact on ED stays.^7–9 However, similar insights for adults are not known. Most importantly, the downstream ED and hospital course and outcomes of asthma patients receiving initial EMS care are not known. This information is important for understanding the systemwide characteristics, course, risk, and outcomes of adults with acute asthma.

Goals of this investigation

In this study, we sought to characterize the demographics, management, and outcomes of adult ED visits for acute asthma and to determine the differences between the patients who do or do not receive initial EMS care.

METHODS Study design and setting

This study was classified as non-human subject research by the Ohio State University Office of Responsible Research Practices.

We analyzed data from the National Hospital Ambulatory Medical Care Survey (NHAMCS).^10,11 The NHAMCS is an annual, national probability sample of ambulatory visits made to non-federal, general, and short-stay hospitals in the United States conducted by the National Center for Health Statistics (NCHS) at the Centers for Disease Control and Prevention (CDC). The survey has been conducted annually since 1992. The ED component of the NHAMCS uses a multistage design composed of 3 stages: (1) 112 geographic primary sampling units that comprise a probability subsample from the 1985 to 1994 National Health Interview Surveys, (2) ≈480 hospitals within primary sampling units, and (3) patient visits within emergency service areas. Sample hospitals are randomly assigned to 16 panels that rotate across thirteen 4-week reporting periods throughout the year. Hospital staff or US Census Bureau field representatives complete a patient record form for each sampled visit according to information obtained from the medical record. The data collected for NHAMCS include information on patient demographics, reasons for visit, vital signs, cause(s) of injury, diagnoses rendered, diagnostic tests ordered, procedures provided, medications prescribed, resources consulted, and disposition, including hospital discharge information if admitted.

Study population

We identified adult ED visits associated with acute asthma by using ED visit International Classification of Diseases, Tenth Revision (ICD-10) diagnoses. The NHAMCS reports up to 3 ICD-10 diagnoses for each ED visit. Patients may report a history that is not directly related to the reasons for ED presentation. Therefore, we devised a hierarchical classification strategy, defining acute asthma as an ED visit with either: (1) ICD-10 code for asthma as the first ED diagnosis or (2) an ICD-10 asthma code for the second ED diagnosis and a concurrent ICD-10 code for a respiratory disease in the first ED diagnosis (Figure 1, Appendix S1). We excluded ED visits with an asthma ICD-10 listed solely in the third ED diagnosis. Because hospital coding practices transitioned from the International Classification of Diseases, Ninth Revision to the ICD-10 in 2015, we limited the analysis to 2016–2019. We limited the cohort to patients age ≥18 years.

FIGURE 1. Taxonomy for identification of emergency department (ED) asthma visits using first 2 National Hospital Ambulatory Medical Care Survey ED diagnoses. Diagnosis no. 3 was not used to identify asthma cases. ICD-10, International Statistical Classification of Diseases, Tenth Revision.

Exposure and outcomes

The primary exposure was mode of ED arrival, defined as arrival by EMS versus other modality, as reported in the data set. Demographic characteristics included patient age, sex, race (White, African American, or other), insurance payor (private, Medicare, Medicaid, or other), and prior medical history of asthma or chronic obstructive pulmonary disease (COPD). Course of ED care included initial vital signs (temperature, heart rate, respiratory rate, systolic and diastolic blood pressure, and pulse oximetry), triage category, laboratory tests (arterial blood gases, basic metabolic panel, creatinine, cardiac enzymes, complete blood count, comprehensive metabolic panel, D-dimer, electrolytes, lactate, liver enzymes, and prothrombin time), and imaging (x-rays). The NHAMCS reports triage category using the Emergency Severity Index (ESI): urgent (“immediate,” “emergent,” or “urgent”) and non-urgent (“semi-urgent” and “non-urgent”).¹² ESI is one of the most widely used ED triaging systems internationally and draws on information regarding patient presentation, vital signs, acuity, and required resource allocation.¹³

The Bottom Line

Little is known about emergency medical services (EMS) care for patients with asthma. Using a large US national database, the authors describe the demographics, treatments, and outcomes of patients with asthma exacerbations treated by EMS. More than 600,000 emergency department (ED) patients with asthma, 1 in 10 of all asthma-related ED visits, were treated by EMS. Patients treated by EMS were of higher acuity, underwent more diagnostic testing in the ED, and were more likely to be admitted to the hospital.

Asthma treatments included medications (short-acting β-agonists, anticholinergics, systemic corticosteroids, and inhaled corticosteroids; Appendix S2) and ED procedures (nebulizer therapy, bilevel positive airway pressure [BiPAP]/continuous positive airway pressure [CPAP], and endotracheal intubation). Outcomes included hospital admission, death in the ED, length of ED stay, and the total length of stay if the patient was hospitalized.

Data analysis

We determined the absolute number and incidence of ED patients with asthma arriving by EMS versus other modalities. We determined differences in ED demographics, course, and outcomes using univariate odds ratios (ORs) with 95% confidence intervals (CIs). To obtain nationally weighted estimates, we accounted for the survey sampling design and weight variables of the NHAMCS data set. Because the NCHS considers estimates with <30% relative standard error or based on <30 raw observations to be unreliable, we collapsed subcategories to ensure that table cells satisfied the requisite number of raw observations. We also noted the estimates limited by the number of raw observations. We conducted the analysis using Stata version 17 (Stata, Inc., College Station, TX).

RESULTS

Between 2016 and 2019, there were an estimated 435 million (95% CI, 394–476 million ) adult ED visits in the United States. Using our classification taxonomy, there were an estimated 5.3 million total acute asthma ED visits, corresponding to ≈1.3 million (1.2%; 95% CI, 1.1%–1.4%) annual acute asthma ED visits. Among ED acute asthma visits, asthma was the first ED diagnosis in 76.5% and the second ED diagnosis in 23.5%. Among ED patients with acute asthma, a total of 602,569 arrived by EMS, corresponding to ≈150,642 annually (11.3%; 95% CI, 8.6%–14.8%) (Figure 2). The percentage of ED acute asthma visits arriving by EMS varied by year: 2016, 16.6%; 2017, 6.7%; 2018, 8.9%; 2019, 11.6%.

FIGURE 2. Study population. Data are from the National Hospital Ambulatory Medical Care Survey, 2016–2019. ED, emergency department; EMS, emergency medical services.

There were no differences in patient age, sex, race, insurance type, or history of asthma or COPD between EMS and non-EMS acute asthma ED visits (Table 1). Acute asthma ED visits in the Northeast census region were more likely to arrive by EMS. There were no differences in time of arrival between EMS and non-EMS ED acute asthma ED visits. Initial ED vital signs were similar between EMS and non-EMS patients with acute asthma (Table 2). However, compared with non-EMS, EMS visits were more likely to present with an “urgent” triage category. EMS patients with acute asthma were more likely to undergo blood tests or imaging. EMS patients with acute asthma were almost twice as likely to receive inhaled anticholinergics in the ED. There were no differences in the ED administration of short-acting β-agonists, systemic corticosteroids, or inhaled corticosteroids between EMS and non-EMS cases. Few acute asthma ED visits involved treatment with BiPAP or CPAP (EMS 1.2% vs non-EMS 0.4%) or endotracheal intubation (EMS 0.4% vs non-EMS 0.0%).

TABLE 1 Demographic characteristics of emergency department asthma visits, stratified by arrival by EMS versus other modality.

Characteristic	Arrival by EMS, n = 602,569; n (%)	Arrival by other modality, n = 4,723,797; n (%)	Total, N = 5,326,366; N (%)	Odds ratio (95% CI)	P value
Census region
Northeast	229,570 (38.1)	822,055 (17.4)	1,051,625 (19.7)	3.37 (1.35–8.42)	0.01
Midwest	120,620 (20.0)	947,378 (20.1)	1,067,998 (20.1)	1.54 (0.56–4.22)	0.40
South	142,494 (23.6)	1,627,998 (34.5)	1,770.492 (33.2)	1.06 (0.39–2.89)	0.92
West	109,885 (18.2)	1,326,366 (28.1)	1,436,251 (27.0)	Reference	–
Time of arrival
8:00–3:00 PM (day)	230,660 (38.8)	1,989,945 (43.5)	2,220,605 (42.9)	Reference	–
4:00–11:00 PM (evening)	235,080 (39.5)	1,503,303 (32.9)	1,738,383 (33.6)	1.34 (0.64–2.82)	0.42
Midnight-7:00 AM (overnight)	129,493 (21.8)	1,081,858 (23.6)	1,211,351 (23.4)	1.03 (0.43–2.47)	0.94
Age
18–39 years	314,865 (52.3)	2,565,668 (54.3)	2,880,534 (54.1)	Reference	–
40 years or older	287,704 (47.7)	2,158,128 (45.7)	2,445,832 (45.9)	1.09 (0.57–2.05)	0.80
Sex
Male	180,102a (29.9)	1,709,509 (36.2)	1,889,610 (35.5)	Reference	–
Female	422,467 (70.1)	3,014,288 (63.8)	3,436,756 (64.5)	1.33 (0.64–2.78)	0.45
Race
White	208,169 (34.5)	2,242,146 (47.5)	2,450,315 (46.0)	Reference	–
Black/African American	154,067* (25.6)	1,305,665 (27.6)	1,459,732 (27.4)	1.27 (0.56–2.90)	0.57
Other	8001a (1.3)	184,245 (3.9)	192,246 (3.6)	0.47 (0.08–2.87)	0.41
Missing	232,333 (38.6)	991,741 (21.0)	1,224,074 (23.0)	N/A
Insurance type
Private	95,032a (15.8)	1,105,533 (23.4)	1,200,565 (22.5)	Reference	–
Medicare	91,618a (15.2)	605,079 (12.8)	696,697 (13.1)	1.76 (0.70–4.42)	0.23
Medicaid and other state programs	244,556 (40.6)	1,738,679 (36.8)	1,983,235 (37.2)	1.64 (0.68–3.93)	0.27
Other	39,531a (6.6)	632,576 (13.4)	672,107 (12.6)	0.73 (0.23–2.33)	0.59
Missing	131,832 (21.9)	641,930 (13.6)	773,761 (14.5)
Medical history
Asthma	602,569 (100.0)	4,723,321 (99.9)	5,325,890 (99.9)	Reference	–
COPD	66,685a (11.1)	347,938 (7.4)	414,623 (7.8)	1.57 (0.54–4.55)	0.41

Note: Data are from the National Hospital Ambulatory Medical Care Survey, 2016–2019.

Abbreviations: CI, confidence interval; COPD, chronic obstructive pulmonary disease; EMS, emergency medical services; N/A, not applicable.

a

Estimates based on <30 raw observations are considered unreliable by the National Center for Health Statistics.

TABLE 2 Presentation and course of emergency department asthma visits, stratified by arrival by EMS versus other modality.

Characteristic	Arrival by EMS, n = 602,569 (11.3); n (%)	Arrival by other modality, n = 4,723,797 (88.7); n (%)	Total, N = 5,326,366; N (%)	Odds ratio (95% CI)	P value
Initial vital signs
Temperature, °F
≤95.0	52,165 (8.7)	229,113 (4.9)	281,278 (5.3)	1.86 (0.61–5.61)	0.27
95.1–99.5	518,176 (86.0)	4,240,219 (89.8)	4,758,395 (89.3)	Reference	–
≥99.6	32,228 (5.3)	254,465 (5.4)	286,693 (5.4)	1.04 (0.23–4.77)	0.96
Heart rate, bpm
≤40	68,975 (11.4)	282,943 (6.0)	351,918 (6.6)	2.17 (0.84–5.60)	0.11
41–80	144,519 (24.0)	914,444 (19.4)	1,058,962 (19.9)	1.41 (0.63–3.15)	0.40
81–120	356,726 (59.2)	3,179,280 (67.3)	3,536,006 (66.4)	Reference	–
≥121	32,349 (5.4)	347,131 (7.3)	379,480 (7.1)	0.83 (0.23–2.94)	0.77
Respiratory rate, breaths/min
≤5	30,281 (5.0)	175,368 (3.7)	205,649 (3.9)	1.41 (0.22–9.02)	0.71
6–15	12,300 (2.0)	100,214 (2.1)	112,514 (2.1)	Reference	–
16–20	401,305 (66.6)	3,143,563 (6.5)	3,544,868 (66.6)	1.04 (0.22–4.86)	0.96
≥21	158,683 (27.6)	1,304,651 (27.6)	1,463,335 (27.5)	0.99 (0.17–0.57)	0.99
BP systolic, mmHg
≤80	0 (0.0)	102,518 (2.2)	102,518 (1.9)	Undefinedb	NA
81–120	216,726 (36.0)	1,060,376 (22.4)	1,277,103 (24.0)	Reference	–
121–160	307,999 (51.1)	2,949,981 (62.4)	3,257,980 (61.2)	0.51 (0.24–1.07)	0.08
>160	77,844 (12.9)	610,921 (12.9)	688,766 (12.9)	0.62 (0.23–1.73)	0.36
Pulse oximetry, SaO2%
<90%	34,260 (5.7)	378,539 (8.0)	412,799 (7.8)	0.69 (0.25–1.88)	0.47
90–95%	143,322 (23.8)	1,110,866 (23.5)	1,254,188 (23.5)	0.98 (0.46–2.12)	0.96
>95%	424,988 (70.5)	3,234,391(68.5)	3,649,379 (68.7)	Reference	–
Triage category
Urgent	443,738 (71.9)	2,454,745 (52.0)	2,898,484 (54.4)	22.2 (6.59–74.91)	<0.001
Non-urgent	7814a (1.3)	960,699 (20.3)	968,514 (18.2)	Reference
Missing	151,016 (25.1)	1,308,353 (27.7)	1,459,368 (27.4)	N/A
Diagnostic tests
Any laboratory test	370,447 (61.5)	1,723,776 (36.5)	2,094,223 (39.3)	2.78 (1.41–5.46)	0.003
Any imaging test	471,684 (78.3)	2,825,066 (59.8)	3,296,750 (61.9)	2.42 (1.21–4.83)	0.01
Medications
Short-acting β-agonists	390,002 (64.7)	2,486,117 (52.6)	2,803,718 (54.0)	1.65 (0.91–3.00)	0.10
Anticholinergics	248,898 (41.3)	1,251,618 (26.5)	1,500,516 (28.2)	1.95 (1.01–3.77)	0.046
Systemic corticosteroids	388,459 (64.5)	3,252,911 (68.9)	3,641,370 (68.4)	0.82 (0.45–1.50)	0.52
Inhaled corticosteroids	35,357a (5.9)	220,299 (4.7)	255,656 (4.8)	1.27 (0.35–4.68)	0.71
Emergency department interventions
Nebulizer therapy	392,966 (65.2)	2,541,010 (53.8)	2,933,976 (55.1)	1.61 (0.86–3.00)	0.13
BiPAP/CPAP	7116a (1.2)	17,426a (0.4)	24,542a (0.5)	3.22 (0.27–39.25)	0.36
Endotracheal intubation	2615a (0.4)	0 (0)	2615a (0.0005)	Undefinedb	–

Note: Data are from the National Hospital Ambulatory Medical Care Survey, 2016–2019.

Abbreviations: BiPAP, bilevel positive airway pressure; BP, blood pressure; CI, confidence interval; CPAP, continuous positive airway pressure; EMS, emergency medical services.

a

Estimates based on <30 raw observations are considered unreliable by the National Center for Health Statistics.

b

Undefined because of zero observations in at least 1 cell.

Patients with acute asthma receiving initial EMS care were ≈3 times more likely to be hospitalized (16.3% vs 6.5%; OR, 2.81; 95% CI, 1.27–6.25) (Table 3). There were no acute asthma deaths in the ED. There were no significant differences in ED length of stay or hospital length of stay between EMS and non-EMS patients with acute asthma.

TABLE 3 Outcomes of emergency department asthma visits, stratified by arrival by EMS versus other modality.

Characteristic	Arrival by EMS,n = 602,569(11.3); n (%)	Arrival by other modality, n = 4,723,797 (88.7); n (%)	Total, N = 5,326,366;N (%)	Odds ratio[95% CI]	P value
Disposition
Discharged home	504,166 (83.7)	4,417,275 (93.5)	4,921,441 (92.4)	Reference
Admitted to hospital	98,403a (16.3)	306,522 (6.5)	404,925 (7.6)	2.81 (1.27–6.25)	0.01
Length of emergency department visit (hours), mean (95% CI)
0–3	115,176 (42.7)	1,302,607 (56.0)	1,417,783 (54.6)
4–6	82,522 (30.6)	747,146 (32.1)	829,668 (32.0)	1.19 (0.45–3.17)	0.73
>6	72,076 (26.7)	275,031 (11.8)	347,106 (13.4)	2.83 (0.92–8.72)	0.07
Length of hospital stay if admitted (days), mean (95% CI)	3.5 (1.6–5.5)	2.9 (1.8–4.1)	3.1 (2.1–4.0)	1.06 (0.82–1.39)	0.64

Note: Data are from the National Hospital Ambulatory Medical Care Survey, 2016–2019.

Abbreviations: CI, confidence interval; EMS, emergency medical services.

a

Estimates based upon <30 raw observations are considered unreliable by the National Center for Health Statistics.

LIMITATIONS

The NHAMCS is a sampled data set, and the resulting national estimates may be influenced by sampling bias. Acute asthma interventions such as inhaled β-agonists and systemic corticosteroids were not captured in the NHAMCS if they were given by EMS before arrival in the ED.¹⁴ In addition, the NHAMCS is designed to describe national ED patterns and may miss granular detail pertinent to ED acute asthma care, such as whether supplemental oxygen was given. Patients arriving by EMS may have received a higher triage category and more intensive treatment as a result of the patient's mode of arrival. We also do not have the timing of procedures and medications, so we cannot know the precise number or sequence of bronchodilator treatments given in the ED. Finally, the number of EMS patients undergoing ED intubations was zero, which is lower than expected in clinical practice.

DISCUSSION

In this study of national ED visits for acute asthma, approximately 1 in 10 received initial care by EMS. Compared with non-EMS cases, EMS patients with acute asthma presented with higher acuity, received more intensive diagnostic tests, and were almost 3 times more likely to be admitted to the hospital. However, we observed no differences in patient demographics, the use of β-agonists or corticosteroids, or ED length of stay. These observations also highlight the need for future research to assess the involvement of EMS in the overall care of ≈11% of adult patients with asthma.

Few prior studies describe EMS care of acute asthma. Using data from the 2018–2019 National Emergency Medical Services Information System, Peters et al identified ≈ 1.34 million (≈0.62 million annually) 911 EMS activations for asthma or COPD.¹⁵ The authors identified a similar number of EMS activations for the treatment of bronchospasm.¹⁶ Although these figures are 5 times higher than our estimates using the NHAMCS data set, the study by Peters et al encompassed a broader range of inclusion criteria encompassing other conditions (asthma and COPD) and symptoms (bronchospasm); neither reported rates of transport to hospital.¹⁷ In a study of 1007 patients with respiratory distress (including 8% with asthma), Kelly et al noted that patients arriving by EMS were more likely to be admitted to the ward or the ICU and had a 3-fold higher hospital mortality.¹⁸ A study of the effects of the Affordable Care Act on EMS use in New York City estimated the prevalence of EMS calls for asthma as 211 per 100,000 people, with 79% for adults aged ≥18 years.¹⁹ Although restricted to the inferences from the NHAMCS data set, our study offers one of the first system-level perspectives of EMS care in the management of ED patients with asthma. Although we could not describe the details of EMS asthma care, we were able to better identify asthma cases using the NHAMCS diagnosis taxonomies, and we were able to characterize subsequent ED course, care, and outcomes.

Although our estimate of the total number of ED acute asthma cases aligns with CDC reports, there are subset characteristics inconsistent with clinical experience.¹ For example, we noted a very small number of intubated patients with acute asthma (n = 2615 in the EMS group and 0 in the non-EMS group). These unexpected results may be related to the design of the NHAMCS, where the sampled data-collection strategy may have missed intubated cases. Prior studies spotlight select inconsistencies of the NHAMCS; for example, Green found that 1 in 4 intubated patients in the NHAMCS were discharged home or admitted to a non-ICU setting, dispositions inconsistent with clinical expectations.²⁰ Prospective data collection is likely necessary to capture more granular data bridging prehospital, ED, and hospital settings.

Our results shed light on the large population of ED patients with acute asthma receiving initial EMS care and the important opportunities for optimizing prehospital asthma care. Acute asthma is a time-dependent condition; early intervention is essential to avert progression to critical illness, respiratory failure, and death.²¹ Potential areas for innovation in the prehospital setting include EMS acute asthma treatment protocols to improve patients' treatments and outcomes.^21–24 For example, accelerated EMS corticosteroid administration has tremendous potential to improve the overall course of acute asthma care.^14,23 As with other time-sensitive conditions such as trauma, myocardial infarction, and stroke, early EMS care can help to accelerate ED care through the early identification of patients and notification of the receiving facility.²⁵ In addition, there is also likely a subset of patients with acute asthma that could be treated by EMS or mobile integrated health units, averting the need for transportation to the ED.²⁶ As with many conditions cared for by EMS, the prehospital encounter could also be leveraged to activate the healthcare system or public health resources, such as linkage to outpatient acute asthma care.

In conclusion, we found that 1 in 10 adult acute asthma ED patients received initial care by EMS. Although limited in information regarding the prehospital course, these findings highlight the potential severity of disease differences between EMS-transported and non-EMS-transported patients with asthma.

AUTHOR CONTRIBUTIONS

Alix Delamare Fauvel contributed to the conceptualization, formal analysis, writing of the original draft, writing review, and editing. Lauren T. Southerland contributed to the conceptualization, writing review, and editing. Ashish R. Panchal contributed to the conceptualization, writing review, and editing. Carlos A. Camargo Jr contributed to the conceptualization, writing review, and editing. Matthew L. Hansen contributed to the conceptualization, writing review, and editing. Henry E. Wang contributed to the conceptualization, methodology, writing review, and editing. All authors have read and agreed to the published version of the article.

CONFLICT OF INTEREST STATEMENTT

Dr. Wang is Editor in Chief of JACEP Open. Dr. Wang had no role in the editorial evaluation of this manuscript.