Effect of Emergency Department Crowding on Pneumonia Admission Care Components

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The American Journal of Managed Care, April 2011, Volume 17, Issue 4

Multivariate analyses associate increased emergency department volume with delayed nursing-dependent care for patients with pneumonia, despite high ratios of nurses to patients.


To determine pneumonia admission care components that are most affected by emergency department (ED) crowding.

Study Design:

Secondary analysis of a crosssectional observational survey.


The setting was a 29-bed academic ED with 39,000 visits per year and state-mandated ratios of nurses to patients. The patients were ED admissions with pneumonia, January 1, 2004, to June 30, 2005. From ED medical records and databases, we abstracted the times of arrival, room placement, ordering of chest radiograph and when obtained, ordering of blood culture and when obtained, and ordering of antibiotic and when administered. We assessed associations between ED volume at the time of arrival of a patient with pneumonia and component durations using multivariate linear regression.


For 407 ED admissions with pneumonia, the median component durations (in minutes) were as follows: 20 for arrival to room placement, 44 for arrival to chest radiograph order, 10 for chest radiograph order to radiograph obtained, 120 for room placement to antibiotic order, 10 for blood culture order to culture obtained, 30 for antibiotic order to antibiotic administered, and 195 for arrival to antibiotic administered. Sixtyone percent of patients received antibiotic within 4 hours. We estimate that for every 10 additional ED patients the time from arrival to ordering of a chest radiograph was prolonged by 14.3 minutes and from ordering of antibiotic to administration by 9.3 minutes.


Despite compliance with mandated ratios of nurses to patients, the time from antibiotic ordering to administration (a nursing task) was prolonged with higher ED volumes, as were throughput measures. Targeting these may expedite treatment under crowded ED conditions.

(Am J Manag Care. 2011;17(4):269-278)

Multivariate analyses associated increased emergency department (ED) volume with delayed nursing-dependent care for patients with pneumonia (time from antibiotic ordering to administration), despite compliance with required ratios of nurses to patients.

  • In our academic ED with strict ratios of nurses to patients, the time from antibiotic ordering to administration (which reflects ED nursing workload) was prolonged in association with increased ED volume.

  • If these findings are reproduced in other settings, EDs may want to focus on nursing processes to find ways to maintain performance during periods of high ED volume, in addition to looking at measures to decrease ED crowding.

Emergency department (ED) crowding delays the time to first antibiotic dose for patients admitted with communityacquired pneumonia.1-3 Pneumonia was one of the initial areas identified by The Joint Commission (TJC) and the Centers for Medicaid and Medicare Services (CMS) as a hospital core measure for quality care. In 2002, TJC and CMS established a target of time to first antibiotic dose within 4 hours of hospital arrival (changed to 6 hours in April 2007) for this publicly reported benchmark and have indicated that hospital and individual physician funding may someday depend on performance on this and other core measures.4,5 Hospitals and physicians attempting to improve performance need to direct limited resources to aspects of care requiring improvement, without sacrificing care provided to others or disrupting processes that work well. It is likely that determining which admission care components are most affected by increasing volume will provide insight into areas for improvement for the care of all ED patients, not just those with pneumonia.

Emergency departments are closely scrutinized for their ability to meet the target to first antibiotic dose, yet the effect of ED volume is just beginning to be recognized.1-3 If a connection between ED volume and particular care components can be established, specific processes could be targeted for quality improvement efforts, without requiring a large influx of resources. This is critical as EDs become increasingly responsible for more time-sensitive interventions (ie, those for patients with trauma, sepsis, stroke, and acute coronary syndrome) and as healthcare dollars shrink. The objective of this investigation was to determine care components provided to patients with pneumonia who were admitted through the ED that were most affected by increasing ED patient volume.


Study Design

This is a secondary analysis of a cross-sectional observational survey of patients admitted through a university tertiary care hospital ED and discharged between January 1, 2004, and June 30, 2005, after an inpatient hospitalization for pneumonia.1 We determined the effect of concurrent ED volume on the duration of care components provided to patients admitted with pneumonia. The study was approved by the committee on human research at our institution.


Our 29-bed academic ED has an annual census of 39,000 and is staffed by emergency medicine, internal medicine, pediatric, and psychiatry residents, as well as nurse practitioners and physician assistants. Patients are seen according to triage acuity. Patient care is supervised 24 hours a day by board-eligible and board-certified emergency physicians. Our ED adheres to a strict ratio of nurses to patients (1:4) as mandated by state law. Dedicated ED radiology technicians are present 24 hours per day. Emergency department triage and physician notes are electronically documented (File-Maker Pro, version 7; FileMaker, Inc, Santa Clara, California). Emergency department orders and nursing notes are handwritten. Physicians and clerical staff notify ED nurses of pending orders by posting an icon on the electronic patient tracking board (GE Centricity; GE Healthcare UK Ltd, Buckinghamshire, England) or by calling with portable phones. These handwritten orders and nursing notes are electronically scanned and stored after the ED visit and are accessible for quality assurance and research.


As part of ongoing quality assurance and TJC/CMS core measure reporting at our institution, an outside vendor (University HealthSystem Consortium, Oak Brook, Illinois) (UHC) reviews medical records of inpatients eligible for TJC/ CMS core measure PN-5b4 (as detailed in a prior study1). The UHC reviewed medical records of all patients meeting

the eligibility criteria from January 1, 2004, through December 31, 2004, in accord with TJC/CMS reporting requirements. Thereafter, the TJC/CMS reporting requirements were revised, and UHC selected a random sample of 75 patients per calendar quarter using a computerized random number generator (SAS version 9.1; SAS Institute Inc, Cary, North Carolina). The UHC excluded patients in accord with TJC/CMS core measure PN-5b exclusion criteria4 (as detailed in a prior study1). Medical records of all remaining patients were reviewed by UHC for antibiotic timing, and the results were reported to our institution. From this group of patients, we selected those admitted through the ED. Analyses were restricted to patients with available data on the time of antibiotic administration.

Data Collection and Processing

Collected from administrative databases were patient demographic and presenting characteristics (age, sex, race/ ethnicity, and mode of arrival [self or ambulance]), triage acuity (1-4, where 1 is emergent), and level of care to which the patient was admitted (intensive care unit or not).1 Using a structured data collection form, we reviewed each patient’s ED medical record to obtain the following: date and time of ED presentation (from the ED triage notes), time of room placement (from the ED nursing notes), time when a chest radiograph was ordered (from the ED orders) and obtained (from the radiology records), time when a blood culture was ordered (from the ED orders) and obtained (from the ED nursing notes), and time when an antibiotic was ordered (from the ED orders) and administered (from the ED nursing notes). For patients with missing or illegible scanned data, we made 3 attempts to obtain the archived paper medical record before reporting the data as unavailable. All data abstraction was performed by 2 of us (CF and CAM), who were not blinded to the study hypothesis but were blinded to ED volume data.

An ED database permits calculation of the hourly ED census on any prior date. From this database, we determined the total number of ED patients who were present at the time of arrival of each patient with pneumonia.

All data were entered into an electronic spreadsheet. Microsoft Excel 97 (Microsoft Corporation, Redmond, Washington) was used.


Figure 1

We calculated the duration of the following care components: ED arrival to ED room placement, ED arrival to chest radiograph order, chest radiograph order to radiograph obtained, blood culture order to culture obtained, room placement to antibiotic order, and antibiotic order to antibiotic administered. We classified care components as related to system hroughput (arrival to room placement and arrival to chest radiograph order) or by provider discipline as follows: radiology technician (chest radiograph order to radiograph obtained), physician (room placement to antibiotic order), and nurse (blood culture order to culture obtained and antibiotic order to antibiotic administered) (). We chose not to calculate time from room placement to chest radiograph order (a potential marker of physician workload), as chest radiographs may be ordered by triage and bedside nurses and physicians at our institution by preestablished protocols; therefore, this care component does not solely reflect physician or nursing workload. Similarly, we did not include time from room placement to blood culture order because nurses often obtain (but do not send) blood cultures before the physician sees the patient and writes this order.

Intervals longer than 600 minutes were analyzed as equal to 600 minutes to limit their influence on the overall results, while still including them as very long intervals. This value was chosen because it was the mean total length of stay of admitted ED patients. If the task was performed before the time of order, we set order times to equal the time of order completion to eliminate negative intervals.


The primary outcome was the time from antibiotic order to antibiotic administered (a nursing task). We chose this a priori based on casual observation that nursing staff seemed busier than physician staff during times of ED crowding. Secondary outcomes included times to completion of each care component.

Primary Data Analysis

We assessed the association of total ED volume with the duration of each care component using multivariate linear regression analysis to control for demographic and presenting characteristics. We also controlled for the time from arrival to the start of the care component to control for the possibility that subsequent intervals would be affected by the previous intervals. For example, if providers were cognizant of delays preceding their involvement, those providers may have behaved differently, either to expedite care intervals to maintain compliance with the antibiotic timing measure or to direct care to sicker patients, having decided that the target could not be met. Patients who had missing values were excluded from the analysis.

Analyses were conducted using commercially available statistical software (SAS version 9.1; SAS Institute, Cary, North Carolina). We used linear regression analysis because results are most meaningfully and interpretably estimated as effects on the mean duration of the measured care component. Because many care components had skewed distributions that resulted in violation of the normality assumption for residuals from the models, we used bias-corrected accelerated bootstrapping to obtain valid confidence intervals (CIs).6 We tested the linearity assumption for continuous predictors by adding quadratic terms. For predictors with strong evidence of nonlinearity, we categorized them into quartiles.


Characteristics of Study Patients

Figure 2

A total of 731 of 898 patients discharged from our hospital with a primary or secondary diagnosis of pneumonia during the study period met eligibility criteria for measure PN-5b and were chosen by UHC for review (). Of this total, 245 (33%) met exclusion criteria. For 79 patients, we could not ascertain the time of antibiotic administration, leaving 407 patients for the final analysis. The initial study1 for which these data were abstracted consisted of 405 patients. Further investigation resulted in 2 additional patients with known time to antibiotic administration. Demographic and presenting characteristics of the study sample are given in Table 1. The median number of ED patients present at the time of arrival of the patients with pneumonia was 24.5 (interquartile range, 17-30; range, 3-52).

Main Findings

Table 2

Table 3

The mean (SD) and median (interquartile range) durations of care components for the study population are given in . The median time from ED arrival to antibiotic administration was 195 minutes (61% received antibiotics within 4 hours of ED arrival). For nursing-dependent intervals (), for every 10 additional ED patients present at the time of arrival of the patients with pneumonia, the time from antibiotic order to antibiotic administered was prolonged by an estimated 9.3 (95% CI, 1.4-19.0) minutes, while the time from blood culture order to culture obtained was not prolonged (−0.4 minutes [95% CI, −7.2 to 7.4]). For system throughput intervals, the time from arrival to chest radiograph order was prolonged by 14.3 (95% CI, 6.5- 24.0) minutes, while the time from arrival to room placement seemed nonlinearly associated and was prolonged most (by 26.0 [95% CI, 10.6-49.0] minutes) at the highest quartile of ED volume. For provider-specific intervals (Tables 4, 5, and 6), the time from chest radiograph order to radiograph obtained (radiology technician dependent) seemed nonlinearly associated with ED volume and was actually reduced (−9.5 [95% CI, −19.1 to −2.0] minutes) in association with the third quartile of ED volume. For each additional 10 patients in the ED, the time from room placement to antibiotic order (physician dependent) was prolonged by 18.1 minutes (95% CI, −5.1 to 43.0), butthis did not reach statistical significance.

Study Limitations

This is a retrospective single-center study, and the findings may not apply to other settings. Two of us not blinded to the study hypothesis performed the medical record abstraction. We do not believe that this biased the results because the abstractors were blinded to the ED volume data. In addition, we did not conduct a random independent audit of medical records to determine the accuracy of the abstraction process.

We chose to use ED volume as a marker of crowding rather than a more complicated derived score because this replicated our prior work and was readily available. Furthermore, there is no compelling evidence that the derived scores outperform simple measures of occupancy.

Although we categorized pneumonia care components by provider discipline, many components, if not all, are dependent on more than 1 type of provider. We could have categorized arrival to chest radiograph order (which was significantly prolonged at the highest ED volume quartile) as a physician-dependent care component. However, times from arrival to chest radiograph order are not solely reflective of the ED physician’s efficiency, as this component may be disproportionately prolonged by delays in rooming patients (system throughput) or abbreviated if the chest radiograph was ordered by the triage or bedside nurse, as per a standing protocol at our ED. Therefore, we categorized this component as related to overall system throughput. In addition, as awareness of the TJC/CMS benchmark increased, physicians were encouraged to order antibiotics along with their initial orders (for intravenous access, laboratory studies, radiographic studies, etc) rather than after reviewing the results of the initial investigations if the diagnosis of pneumonia was certain. This change in practice could have artificially prolonged the time from antibiotic order to antibiotic administered as nurses went through the steps necessary for antibiotic delivery. However, in our prior study1 among this same sample, we did not find a differential effect of crowding over the duration of the investigation.

Our models did not account for physician or nursing staffing levels, which were unavailable. It is possible that small increases in patient volume are magnified during periods of lesser staffing. In addition, missing data for variables that were included in the models may have altered the results. The influence of the number of ED patients present at arrival on the chance of being excluded from the models in Tables 3, 4, 5, and 6 seemed to be small (all odds ratios were <1.14 per additional 10 patients, and all CIs extended down to at least 0.92).

Our findings must be tempered by the fact that we conducted multiple analyses and that this is a secondary analysis. Our results suggest that ED volume affects nursing care and throughput measures more so than other care components, but these associations need to be confirmed in further work.

Finally, if crowding increases both the time from ED arrival to the start of care and the duration of subsequent intervals, then controlling for the elapsed time to the start of the intern val could be “overcontrolling,” meaning that we control away some of the effect that we are actually looking for. We do not believe that this is the case because the estimates for the previous interval are all small or negative.


We found that 3 care components provided to patients with pneumonia admitted to the hospital through the ED were prolonged in association with increasing ED volume. Two of these, not surprisingly, reflected overall ED throughput. The third, the time from antibiotic order to antibiotic administered, reflects nursing workload. The time from room placement to antibiotic order (physician specific) may also be prolonged, but this did not reach statistical significance.

There is mounting evidence of the detrimental effects of crowding on the quality of care provided to ED patients, with delays in the first antibiotic dose for patients with pneumonia and analgesia administration, lower adherence to acute coronary syndrome guidelines, increased rates of patients who leave without being seen, and poorer patient satisfaction.1-3,7-12 The aim of this study was to determine if particular care components provided to ED patients with pneumonia were more vulnerable to an increasing ED volume than other components. Identification of susceptible care components would provide specific targets for efforts aimed at improving the quality of care for ED patients admitted with pneumonia when it is impossible to move patients out of the ED.

Our finding that a nursing-dependent action was significantly delayed in association with increasing ED volume was particularly notable because we adhere to a state-mandated ratio of nurses to patients. In 2004, California became the first state to mandate minimum ratios of nurses to patients. This legislation resulted in increased use of registered nurses, but it is unclear if there has been an effect on quality measures associated with nursing care.13

We believe that one explanation for the effect on nursing care, even in a system with mandatory ratios, is the underlying cause of crowding. Emergency department crowding often results from boarding admitted patients with complex needs.14 Nursing attention in the ED may be diverted to inpatient tasks15 and to inpatient unit call reports (often repeatedly), which may result in reduced time to devote to newly roomed patients and in less opportunity to obtain or provide backup from or to other nurses. It is also possible that physician or clerical staff communication with nursing staff regarding pending orders (such as a pending antibiotic order) may break down during times of increased ED volume. To more formally address these questions, focus groups or time-and-motion studies should determine how a nurse’s workload differs between crowded and noncrowded ED states and suggest measures that might be taken to maintain flow. When crowded, reallocating nursing staff to the ED (eg, from a float pool) or developing methods to improve communication of pending orders may improve compliance with antibiotic timing. Adding nonnursing personnel who can perform tasks that ED nurses currently perform (such as obtaining intravenous access, blood draws for routine laboratory workup, and blood cultures) may inn crease the time available for ED nurses to devote to medication administration or other nursing-specific activities.

Another nursing care component, blood culture order to culture obtained, did not seem to be substantially prolonged in association with increasing ED volume. In our ED, the patient’s nurse (without a physician order) will often obtain a blood culture at the time when intravenous access is established (particularly if the nurse suspects an infectious etiology), thus reducing the likelihood of an association between ED volume and a prolonged interval from blood culture order to culture obtained. This suggests that nursing care could be expedited by allowing more autonomy for nurses or by creating protocols that would allow a series of uninterrupted steps that do not require waiting for a physician order.

It is worth noting the association between ED volume and delays in arrival to room placement and arrival to chest radiograph order. Our results suggest that system changes aimed at improving the flow to room placement or expediting the ordering of chest radiographs before room placement may improvethe time to antibiotic administration. The latter may be accomplished by instituting protocols or by using senior nurses, nurse practitioners or physician assistants, or physicians at triage. We caution against doing so solely for patients with possible pneumonia, as this would require increased staffing, may unintentionally divert attention and resources from other equally or more acutely ill patients, and may be financially prudent only if done for all patients requiring chest radiographs and other investigations that could be performed by ancillary personnel.

We also note that 1 physician-dependent interval (room placement to antibiotic order) was estimated to be prolonged by 18 minutes because of ED crowding, although this did not reach statistical significance. The wide CIs may reflect the fact that physicians are responsible for an increasing number and heterogeneity of patients as the ED becomes more crowded, rendering it likely that they will have to focus on sicker patients and thus be delayed in providing care for stable patients with pneumonia. At the same time, physician tasks (examining the patient, reviewing the laboratory results and radiographs, and writing orders) are less procedurally oriented than nursing tasks (establishing intravenous access, drawing and labeling blood, ordering or mixing medications, setting pumps, etc), making it easier for physicians to see multiple patients in a short period.

Author Affiliations: From the Department of Emergency Medicine (CF, EJW), University of California, San Francisco Medical Center, San Francisco, CA; Department of Epidemiology and Biostatistics (PB), University of California, San Francisco Medical Center, San Francisco, CA; Section of Emergency Medicine (CAM), Virginia Mason Medical Center, Seattle, WA.

Funding Source: None.

Author Disclosures: The authors (CF, EJW, PB, CAM) report no relationship or financial interest with any entity that would pose a conflict of interest with the subject matter of this article.

Authorship Information: Concept and design (CF, EJW); acquisition of data (CF, CAM); analysis and interpretation of data (CF, EJW, PB, CAM); drafting of the manuscript (CF, EJW, CAM); critical revision of the manuscript for important intellectual content (CF, EJW, PB, CAM); and statistical analysis (PB).

Address correspondence to: Christopher Fee, MD, Department of Emergency Medicine, University of California, San Francisco Medical Center, 505 Parnassus Ave, Box 0208, San Francisco, CA 94143. E-mail: christopher.fee@ucsf.edu.

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