0
Original Research: Critical Care |

The Effect of Point-of-Care Ultrasonography on Imaging Studies in the Medical ICUMedical ICU Point-of-Care Ultrasonography: A Comparative Study FREE TO VIEW

Margarita Oks, MD; Krystal L. Cleven, MD; Jose Cardenas-Garcia, MD; Jennifer Ann Schaub, MD; Seth Koenig, MD, FCCP; Rubin I. Cohen, MD, FCCP; Paul H. Mayo, MD, FCCP; Mangala Narasimhan, DO, FCCP
Author and Funding Information

From the Hofstra North Shore Long Island Jewish School of Medicine (Drs Oks, Cleven, Cardenas-Garcia, Koenig, Cohen, Mayo, and Narasimhan), Hempstead, NY; and Yale New-Haven Hospital (Dr Schaub), New Haven, CT.

CORRESPONDENCE TO: Margarita Oks, MD, Department of Medicine, North Shore Long Island Jewish Health System, 300 Community Dr, Fourth Floor, Manhasset, NY 11030; e-mail: moks@nshs.edu


Part of this article has been presented and published in abstract form at CHEST 2013, October 26-31, 2013, Chicago, IL (Oks M, Cohen R, Koenig S, Narasimhan M. Chest. 2013;144[4_MeetingAbstracts]:542A).

FUNDING/SUPPORT: The authors have reported to CHEST that no funding was received for this study.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians. See online for more details.


Chest. 2014;146(6):1574-1577. doi:10.1378/chest.14-0728
Text Size: A A A
Published online

BACKGROUND:  Point-of-care ultrasonography performed by frontline intensivists offers the possibility of reducing the use of traditional imaging in the medical ICU (MICU). We compared the use of traditional radiographic studies between two MICUs: one where point-of-care ultrasonography is used as a primary imaging modality, the other where it is used only for procedure guidance.

METHODS:  This study was a retrospective 3-month chart review comparing the use of chest radiographs, CT scans (chest and abdomen/pelvis), transthoracic echocardiography performed by the cardiology service, and DVT ultrasonography studies performed by the radiology service between two MICUs of similar size and acuity and staffing levels.

RESULTS:  Total number of admissions, patient demographics, and disease acuity were similar between MICUs. Comparing the non-point-of-care ultrasonography MICU with the point-of-care ultrasonography MICU, there were 3.75 ± 4.6 vs 0.82 ± 1.85 (P < .0001) chest radiographs per patient, 0.10 ± 0.31 vs 0.04 ± 0.20 (P = .0007) chest CT scans per patient, 0.17 ± 0.44 vs 0.05 ± 0.24 (P < .0001) abdomen/pelvis CT scans per patient, 0.20 ± 0.47 vs 0.02 ± 0.14 (P < .0001) radiology service-performed DVT studies per patient, and 0.18 ± 0.40 vs 0.07 ± 0.26 (P < .0001) cardiology service-performed transthoracic echocardiography studies per patient, respectively.

CONCLUSIONS:  The use of point-of-care ultrasonography in an MICU is associated with a significant reduction in the number of imaging studies performed by the radiology and cardiology services.

Critical care ultrasonography is performed by frontline intensivists to establish diagnosis and to guide the management of critically ill patients. The critical care clinician who uses point-of-care ultrasonography is personally responsible for image acquisition and immediate interpretation of the acquired data. This is different from the traditional approach to imaging studies in the medical ICU (MICU), where the radiology and cardiology services are responsible for image acquisition and interpretation. It is not clear whether the use of critical care ultrasonography reduces the use of traditional imaging techniques in the MICU, such as chest radiography, CT scanning, transthoracic echocardiography (TTE), and DVT study. This study compares the use of traditional imaging studies between two MICUs: one where point-of-care ultrasonography is used as the primary imaging modality and the other where ultrasonography is used only for procedure guidance.

Study Site and Design

This study was a retrospective chart review of a 3-month period from April to June 2012 that compared the rate of imaging studies performed by the radiology and cardiology services between two MICUs. The North Shore Long Island Jewish Health System is a nonprofit health-care organization located in the greater New York metropolitan area. This study was carried out in the MICU of two tertiary care teaching hospitals of the system: Long Island Jewish Medical Center (LIJ) and North Shore University Hospital (NSUH). Both MICUs are closed-book units and staffed by full-time attending physicians with 24-h coverage, pulmonary critical care medicine fellows, and internal medicine and emergency medicine residents. Both LIJ and NSUH MICUs have 18 beds and an average of 1,200 to 1,300 admissions per year.

Although similar in size, staffing, and clinical capabilities, at the time of the study the two MICUs used critical care ultrasonography in very different ways. At the NSUH MICU, ultrasonography was used routinely for guided insertion of central venous catheters and performance of thoracenteses but not for other applications. In general, the attending staff in charge of the NSUH MICU did not have experience with other aspects of critical care ultrasonography and, thus, did not use it regularly. In contrast, the attending staff in charge of the LIJ MICU had full competence1 in all aspects of critical care ultrasonography and used point-of-care ultrasonography regularly for diagnosis and patient management as well as for procedure guidance. Specifically, the LIJ MICU had three fully capable ultrasound machines (M-Turbo; FUGIFILM SonoSite, Inc) that were always positioned in the unit. On morning rounds, an ultrasound machine accompanied the team to the bedside of every patient, with a team member specifically assigned to perform the appropriate examination to give immediate results to the team. Based on the results of the bedside examination, the MICU team made immediate diagnostic and management decisions. After morning rounds, the machines were available and used regularly for follow-up examinations and evaluation of new admissions, disease evolution, hemodynamic function, and changes in critical condition. Three of the full-time attending physicians at the LIJ MICU were fully trained in advanced critical care echocardiography, including transesophageal echocardiography. There was no established protocol at either MICU requiring daily chest radiographs for intubated patients.

This research was approved by the institutional review board of the North Shore Long Island Jewish Health System (study number 13-500A). The requirement for informed consent was waived by the institutional review board.

Outcome Measurements

One investigator reviewed all MICU admissions at both LIJ and NSUH for the study period and abstracted basic demographics and indicators of disease severity. The Charlson Comorbidity Index (CCI) was used for objective assessment of disease acuity. The CCI is an age-adjusted index based on 19 preexisting conditions obtained from International Classification of Diseases, Ninth Revision, codes on patient admission. The CCI correlates with mortality, with each point correlating with a relative risk of 2.3% mortality rate at 1 year. The CCI has been compared against physiology-based scores, such as the APACHE (Acute Physiology and Chronic Health Evaluation) and Simplified Acute Physiology Score II and III, and has been shown to comparably predict mortality rates.26 The data for calculation of retrospective APACHE scores were not available. The cardiology and radiology imaging studies performed while the patients were in the MICU were recorded. Deidentified data were entered into a standard spreadsheet for subsequent analyses. The number of chest radiographs, chest CT scans, abdomen/pelvis CT scans, cardiology service-performed TTE studies, and radiology service-performed DVT studies were tallied for each patient during his or her stay in the MICU.

Statistical Analysis

Descriptive statistics were calculated for all data collected because the data were not normally distributed. The t test was used to compare continuous variables, and the χ2 test was used to compare categorical variables. Wilcoxon rank sum was used to calculate statistical significance (defined as a P < .05) in the number of imaging studies ordered. Statistical analyses were completed using SAS version 9.2 software (SAS Institute Inc).

The patient demographics, mean length of stay, CCI scores, and predicted mortality rates are presented in Table 1. The number of studies per patient performed at each MICU are shown in Table 2.

Table Graphic Jump Location
TABLE 1 ]  Patient Group Characteristics

Data are presented as mean ± SD unless otherwise indicated. CCI = Charlson Comorbidity Index; LIJ = Long Island Jewish Medical Center; MICU = medical ICU; NS = not significant; NSUH = North Shore University Hospital.

Table Graphic Jump Location
TABLE 2 ]  Number of Studies per Patient

Data are presented as mean ± SD (total No. of studies). TTE = transthoracic echocardiography. See Table 1 legend for expansion of other abbreviations.

This study compared the use of traditional imaging studies in two MICUs that were similar in terms of number of beds, medical staffing, number of admissions, and patient disease severity but differed in their use of critical care bedside ultrasonography. The number of chest radiographs, body CT scans, cardiology service-performed TTE studies, and radiology service-performed DVT studies were all significantly reduced in the LIJ MICU, where the intensivists used ultrasonography as the primary imaging modality. The reduction of chest radiographs in the LIJ MICU occurred in the context that neither MICU had protocols mandating daily chest radiographs for intubated patients. We conclude that the use of point-of-care ultrasonography by intensivists is associated with a reduction in both radiographic and nonradiographic imaging studies performed by the radiology and cardiology services in the MICU.

Given this observed association, several advantages may accrue with the use of bedside ultrasonography in the MICU. Several studies have documented increased complications and mortality risk associated with intrahospital transport from the ICU to the radiology suite for imaging studies such as CT scanning. These complications include hypotension, arrhythmias, hypoxia, and cardiac arrest711 as well as ventilator-associated pneumonia.12,13 Another problem is that transport of the unstable patient through the hospital requires increased staff resources, which often are not available.14,15 Radiation exposure is a major concern with CT scanning1622; thus, point-of-care ultrasonography may reduce the need for CT scans.23 Cost reduction is another potential benefit of point-of-care ultrasonography in the MICU. We did not attempt a cost analysis for imaging services between the two MICUs. From a reimbursement standpoint, the quantitative cost of an imaging procedure in the hospitalized patient is difficult to measure because reimbursement is based on a diagnostic-related category rather than on the cost of an individual procedure. At the qualitative level, bedside ultrasonography likely reduces the cost of imaging in the MICU from the standpoint of hospital costs.

This study has several limitations. First, it was an unblinded retrospective chart review, and with the data not being normally distributed, it required the use of nonparametric analysis techniques. Despite this, we were able to detect a statistically significant difference in the use of traditional imaging studies between the two MICUs. Second, although both MICUs were similar in size and staffing, alternative factors could influence decisions of the two clinical teams to order more or fewer traditional imaging studies, such as personal practice styles, a generally different level of expertise in critical care medicine as reflected by the lack of use of bedside ultrasonography, or various levels of perception of medicolegal risk. Third, simple demographics and severity of disease as measured by the CCI were similar between the two MICUs, but many other factors need to be measured before concluding that the two patient groups were well matched. Fourth, we collected no data on the type, indication, results, or clinical effect of ultrasonography. We only can report that ultrasonography was fully integrated into the functioning of one MICU but not the other. Finally, the results of this study cannot be readily generalized to another MICU. The LIJ MICU approach to critical care ultrasonography requires several dedicated machines, a number of frontline intensivists skilled in critical care ultrasonography, the deployment of ultrasonography as a primary tool on work rounds, a team decision to rely as much as possible on ultrasonography as a primary imaging tool, and the decision that confirmatory imaging is not required for ultrasonography examinations performed by the MICU team. For example, several of the intensivists in the LIJ MICU were fully trained in echocardiography, which may have reduced the need for full echocardiographic studies performed by the cardiology service; this may not be the case for other MICUs.

The use of point-of-care ultrasonography by intensivists in the MICU is associated with a reduced number of imaging studies performed by radiology and cardiology services compared with a similar MICU that did not use bedside ultrasonography. The use of daily intensivist-performed critical care ultrasonography offers the potential for reducing risk associated with patient transport, radiation exposure, and hospital costs.

Author contributions: M. O. and M. N. had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. M. O. contributed to the study concept and design, data acquisition and interpretation, and drafting of the manuscript; K. L. C. and J. C.-G. contributed to the data acquisition and interpretation and drafting and final approval of the manuscript; J. A. S. contributed to the data analysis and interpretation and drafting and final approval of the manuscript; and S. K., R. I. C., P. H. M., and M. N. contributed to the study concept and design, critical revision of the manuscript for important intellectual content, and final approval of the manuscript.

Financial/nonfinancial disclosures: The authors have reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

CCI

Charlson Comorbidity Index

LIJ

Long Island Jewish Medical Center

MICU

medical ICU

NSUH

North Shore University Hospital

TTE

transthoracic echocardiography

Mayo PH, Beaulieu Y, Doelken P, et al. American College of Chest Physicians/La Société de Réanimation de Langue Française statement on competence in critical care ultrasonography. Chest. 2009;135(4):1050-1060. [CrossRef] [PubMed]
 
Christensen S, Johansen MB, Christiansen CF, Jensen R, Lemeshow S. Comparison of Charlson comorbidity index with SAPS and APACHE scores for prediction of mortality following intensive care. Clin Epidemiol. 2011;3:203-211. [CrossRef] [PubMed]
 
Needham DM, Scales DC, Laupacis A, Pronovost PJ. A systematic review of the Charlson comorbidity index using Canadian administrative databases: a perspective on risk adjustment in critical care research. J Crit Care. 2005;20(1):12-19. [CrossRef] [PubMed]
 
Charlson ME, Pompei P, Ales KL, MacKenzie CR. A new method of classifying prognostic comorbidity in longitudinal studies: development and validation. J Chronic Dis. 1987;40(5):373-383. [CrossRef] [PubMed]
 
Hall WH, Ramachandran R, Narayan S, Jani AB, Vijayakumar S. An electronic application for rapidly calculating Charlson comorbidity score. BMC Cancer. 2004;4(94):94. [CrossRef] [PubMed]
 
Grendar J, Shaheen AA, Myers RP, et al. Predicting in-hospital mortality in patients undergoing complex gastrointestinal surgery: determining the optimal risk adjustment method. Arch Surg. 2012;147(2):126-135. [CrossRef] [PubMed]
 
Hurst JM, Davis K Jr, Johnson DJ, Branson RD, Campbell RS, Branson PS. Cost and complications during in-hospital transport of critically ill patients: a prospective cohort study. J Trauma. 1992;33(4):582-585. [CrossRef] [PubMed]
 
Szem JW, Hydo LJ, Fischer E, Kapur S, Klemperer J, Barie PS. High-risk intrahospital transport of critically ill patients: safety and outcome of the necessary “road trip.” Crit Care Med. 1995;23(10):1660-1666. [CrossRef] [PubMed]
 
Evans A, Winslow EH. Oxygen saturation and hemodynamic response in critically ill, mechanically ventilated adults during intrahospital transport. Am J Crit Care. 1995;4(2):106-111. [PubMed]
 
Braman SS, Dunn SM, Amico CA, Millman RP. Complications of intrahospital transport in critically ill patients. Ann Intern Med. 1987;107(4):469-473. [CrossRef] [PubMed]
 
Voigt LP, Pastores SM, Raoof ND. Review of a large clinical series: intrahospital transport of critically ill patients: outcomes, timing, and patterns. J Intensive Care Med. 2009;24(2):108-115. [CrossRef] [PubMed]
 
Kollef MH, Von Harz B, Prentice D, et al. Patient transport from intensive care increases the risk of developing ventilator-associated pneumonia. Chest. 1997;112(3):765-773. [CrossRef] [PubMed]
 
Bercault N, Wolf M, Runge I, Fleury JC, Boulain T. Intrahospital transport of critically ill ventilated patients: a risk factor for ventilator-associated pneumonia—a matched cohort study. Crit Care Med. 2005;33(11):2471-2478. [CrossRef] [PubMed]
 
Kue R, Brown P, Ness C, Scheulen J. Adverse clinical events during intrahospital transport by a specialized team: a preliminary report. Am J Crit Care. 2011;20(2):153-161. [CrossRef] [PubMed]
 
McLenon M. Use of a specialized transport team for intrahospital transport of critically ill patients. Dimens Crit Care Nurs. 2004;23(5):225-229. [CrossRef] [PubMed]
 
Smith-Bindman R. Is computed tomography safe? N Engl J Med. 2010;363(1):1-4. [CrossRef] [PubMed]
 
Diederich S, Lenzen H. Radiation exposure associated with imaging of the chest: comparison of different radiographic and computed tomography techniques. Cancer. 2000;89(suppl 11):2457-2460. [CrossRef] [PubMed]
 
Mettler FA Jr, Thomadsen BR, Bhargavan M, et al. Medical radiation exposure in the U.S. in 2006: preliminary results. Health Phys. 2008;95(5):502-507. [CrossRef] [PubMed]
 
Mayo JR, Aldrich J, Muller NL; Fleischner Society. Radiation exposure at chest CT: a statement of the Fleischner Society. Radiology. 2003;228(1):15-21. [CrossRef] [PubMed]
 
Berrington de González A, Mahesh M, Kim KP, et al. Projected cancer risks from computed tomographic scans performed in the United States in 2007. Arch Intern Med. 2009;169(22):2071-2077. [CrossRef] [PubMed]
 
Smith-Bindman R, Lipson J, Marcus R, et al. Radiation dose associated with common computed tomography examinations and the associated lifetime attributable risk of cancer. Arch Intern Med. 2009;169(22):2078-2086. [CrossRef] [PubMed]
 
Smith-Bindman R, Miglioretti DL, Johnson E, et al. Use of diagnostic imaging studies and associated radiation exposure for patients enrolled in large integrated health care systems, 1996-2010. JAMA. 2012;307(22):2400-2409. [CrossRef] [PubMed]
 
Peris A, Tutino L, Zagli G, et al. The use of point-of-care bedside lung ultrasound significantly reduces the number of radiographs and computed tomography scans in critically ill patients. Anesth Analg. 2010;111(3):687-692. [CrossRef] [PubMed]
 

Figures

Tables

Table Graphic Jump Location
TABLE 1 ]  Patient Group Characteristics

Data are presented as mean ± SD unless otherwise indicated. CCI = Charlson Comorbidity Index; LIJ = Long Island Jewish Medical Center; MICU = medical ICU; NS = not significant; NSUH = North Shore University Hospital.

Table Graphic Jump Location
TABLE 2 ]  Number of Studies per Patient

Data are presented as mean ± SD (total No. of studies). TTE = transthoracic echocardiography. See Table 1 legend for expansion of other abbreviations.

References

Mayo PH, Beaulieu Y, Doelken P, et al. American College of Chest Physicians/La Société de Réanimation de Langue Française statement on competence in critical care ultrasonography. Chest. 2009;135(4):1050-1060. [CrossRef] [PubMed]
 
Christensen S, Johansen MB, Christiansen CF, Jensen R, Lemeshow S. Comparison of Charlson comorbidity index with SAPS and APACHE scores for prediction of mortality following intensive care. Clin Epidemiol. 2011;3:203-211. [CrossRef] [PubMed]
 
Needham DM, Scales DC, Laupacis A, Pronovost PJ. A systematic review of the Charlson comorbidity index using Canadian administrative databases: a perspective on risk adjustment in critical care research. J Crit Care. 2005;20(1):12-19. [CrossRef] [PubMed]
 
Charlson ME, Pompei P, Ales KL, MacKenzie CR. A new method of classifying prognostic comorbidity in longitudinal studies: development and validation. J Chronic Dis. 1987;40(5):373-383. [CrossRef] [PubMed]
 
Hall WH, Ramachandran R, Narayan S, Jani AB, Vijayakumar S. An electronic application for rapidly calculating Charlson comorbidity score. BMC Cancer. 2004;4(94):94. [CrossRef] [PubMed]
 
Grendar J, Shaheen AA, Myers RP, et al. Predicting in-hospital mortality in patients undergoing complex gastrointestinal surgery: determining the optimal risk adjustment method. Arch Surg. 2012;147(2):126-135. [CrossRef] [PubMed]
 
Hurst JM, Davis K Jr, Johnson DJ, Branson RD, Campbell RS, Branson PS. Cost and complications during in-hospital transport of critically ill patients: a prospective cohort study. J Trauma. 1992;33(4):582-585. [CrossRef] [PubMed]
 
Szem JW, Hydo LJ, Fischer E, Kapur S, Klemperer J, Barie PS. High-risk intrahospital transport of critically ill patients: safety and outcome of the necessary “road trip.” Crit Care Med. 1995;23(10):1660-1666. [CrossRef] [PubMed]
 
Evans A, Winslow EH. Oxygen saturation and hemodynamic response in critically ill, mechanically ventilated adults during intrahospital transport. Am J Crit Care. 1995;4(2):106-111. [PubMed]
 
Braman SS, Dunn SM, Amico CA, Millman RP. Complications of intrahospital transport in critically ill patients. Ann Intern Med. 1987;107(4):469-473. [CrossRef] [PubMed]
 
Voigt LP, Pastores SM, Raoof ND. Review of a large clinical series: intrahospital transport of critically ill patients: outcomes, timing, and patterns. J Intensive Care Med. 2009;24(2):108-115. [CrossRef] [PubMed]
 
Kollef MH, Von Harz B, Prentice D, et al. Patient transport from intensive care increases the risk of developing ventilator-associated pneumonia. Chest. 1997;112(3):765-773. [CrossRef] [PubMed]
 
Bercault N, Wolf M, Runge I, Fleury JC, Boulain T. Intrahospital transport of critically ill ventilated patients: a risk factor for ventilator-associated pneumonia—a matched cohort study. Crit Care Med. 2005;33(11):2471-2478. [CrossRef] [PubMed]
 
Kue R, Brown P, Ness C, Scheulen J. Adverse clinical events during intrahospital transport by a specialized team: a preliminary report. Am J Crit Care. 2011;20(2):153-161. [CrossRef] [PubMed]
 
McLenon M. Use of a specialized transport team for intrahospital transport of critically ill patients. Dimens Crit Care Nurs. 2004;23(5):225-229. [CrossRef] [PubMed]
 
Smith-Bindman R. Is computed tomography safe? N Engl J Med. 2010;363(1):1-4. [CrossRef] [PubMed]
 
Diederich S, Lenzen H. Radiation exposure associated with imaging of the chest: comparison of different radiographic and computed tomography techniques. Cancer. 2000;89(suppl 11):2457-2460. [CrossRef] [PubMed]
 
Mettler FA Jr, Thomadsen BR, Bhargavan M, et al. Medical radiation exposure in the U.S. in 2006: preliminary results. Health Phys. 2008;95(5):502-507. [CrossRef] [PubMed]
 
Mayo JR, Aldrich J, Muller NL; Fleischner Society. Radiation exposure at chest CT: a statement of the Fleischner Society. Radiology. 2003;228(1):15-21. [CrossRef] [PubMed]
 
Berrington de González A, Mahesh M, Kim KP, et al. Projected cancer risks from computed tomographic scans performed in the United States in 2007. Arch Intern Med. 2009;169(22):2071-2077. [CrossRef] [PubMed]
 
Smith-Bindman R, Lipson J, Marcus R, et al. Radiation dose associated with common computed tomography examinations and the associated lifetime attributable risk of cancer. Arch Intern Med. 2009;169(22):2078-2086. [CrossRef] [PubMed]
 
Smith-Bindman R, Miglioretti DL, Johnson E, et al. Use of diagnostic imaging studies and associated radiation exposure for patients enrolled in large integrated health care systems, 1996-2010. JAMA. 2012;307(22):2400-2409. [CrossRef] [PubMed]
 
Peris A, Tutino L, Zagli G, et al. The use of point-of-care bedside lung ultrasound significantly reduces the number of radiographs and computed tomography scans in critically ill patients. Anesth Analg. 2010;111(3):687-692. [CrossRef] [PubMed]
 
NOTE:
Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging & repositioning the boxes below.

Find Similar Articles
CHEST Journal Articles
PubMed Articles
Guidelines
Diagnosis and treatment of ischemic stroke.
Institute for Clinical Systems Improvement
  • CHEST Journal
    Print ISSN: 0012-3692
    Online ISSN: 1931-3543