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Keywords:Arterial blood gasVentilator daysRoutine testingUnnecessary testingIntensive care unit

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Journal of Critical Care 30 (2015) 438.e1438.e5

Contents lists available at ScienceDirect

Journal of Cr

j ourna l homepage: wthe assessment of acid base status [4]. The current literature suggests ed; a change in patientmanagement based on theABG results occurred in

42% of cases; and ABG analysis was frequently performed on a routineare the need to evaluate the adequacy of patient ventilation, the need toquantify the response to therapeutic or diagnostic interventions, moni-toring of severity and progression of documented disease process, and

zation survey inquiring about the level of training of the ordering clini-cian, reason for ordering ABG, and the effect of the results on patientmanagement. The study showed that 79%of ABG test resultswere expect-an ABG sample should be obtained, when the results are highly likely toinuence patientmanagement [3]. Common indications for ABG sample

[3]. In 2007, Melanson et al [3] determined the utiin a tertiary care hospital by having physicians an1. Introduction

Respiratory depression is a potentially lethal condition and hasreceived much attention in the literature [1]. Hypercapnia is a directindicator of respiratory depression, and arterial blood gas (ABG)analysis is an accurate and reliable tool to evaluate hypercapnia in thecontext of respiratory diseases and conditions affecting the lungs [2].Most ABG samples are obtained in the Intensive Care Unit (ICU). Ideally,

that indications for ABG analysis should be based on the clinical assess-ment of the patient.

Arterial puncture for ABG analysis is an invasive procedure; andpotential complications include occlusion of the artery, digitalembolization leading to digital ischemia, sepsis, local infection,pseudoaneurysm, hematoma, bleeding, and skin necrosis [5]. Arterialblood gas samples are frequently obtained for reasons such as change inventilator settings, a respiratory or cardiac event, and as routine testing Conict of interest disclosure: The authors declare tother conict of interest related to the submitted manusc Corresponding author at: Department of Internal Med

4646 North Marine Drive, Chicago, IL 60640. Tel.: +1 773E-mail address: fblum@weisshospital.com (F.E. Blum)

http://dx.doi.org/10.1016/j.jcrc.2014.10.0250883-9441/ 2014 Elsevier Inc. All rights reserved.patients; P = .007) was found along with a decrease in the number of ventilator days per patient (P = .004)and a shorter length of stay for ventilated patients in group 2 compared with group 1 (P= .04).Conclusion: A signicant decrease of ABGs obtained in the ICU does not negatively impact patient outcomeand safety. A decrease in the number of ABGs per patient allows cost-efcient patient care with a lower riskfor complications.

2014 Elsevier Inc. All rights reserved.Purpose:Arterial blood gas (ABG) analysis is a useful tool to evaluate hypercapnia in the context of conditions anddiseases affecting the lungs. Oftentimes, indications for ABG analysis are broad and nonspecic and lead tofrequent testing without test results inuencing patient management.Materials and methods: Electronic charts of 300 intensive care unit (ICU) patients at a single institution werereviewed retrospectively. Reassessment of indications for ABGs led to a decrease of the number of ABGs in theICU betweenMarch andNovember 2012. Data relating to ventilator days, length of stay, number of reintubations,mortality, complications after arterial puncture, demographics, and medications in 159 ICU patientsbetween December 2011 and February 2012 (group 1) were compared with 141 ICU patients betweenDecember 2012 and February 2013 (group 2). Subgroup analysis in ventilated patients was performed.Results: A decrease of number of ABGs per patient (6.12 5.9, group 1 vs 2.03 1.66, group 2 in ventilateda b s t r a c ta r t i c l e i n f oReevaluation of the utilization of arterial bIntensive Care Unit: Effects on patient safe

Franziska E. Blum, MD a,, Elisa Takalo Lund, MS a, HeaEdgar G. Chedrawy, MD, MSc c,d, Jeffrey Zilberstein, Ma Department of Internal Medicine, Weiss Memorial Hospital, afliate of the University of Illinob Department of Vascular Surgery, Weiss Memorial Hospital, Chicago, ILc Department of Cardiovascular and Thoracic Surgery, Weiss Memorial Hospital, Chicago, ILd Department of Cardiothoracic Surgery, University of IllinoisChicago at Chicago, Chicago, ILe Department of Medicine, Section of Pulmonary, Critical Care, Sleep and Allergy, University ofhat they have no nancial andript.icine,WeissMemorial Hospital,5647400; fax: +1 7735645226..od gas analysis in theand patient outcome

er A. Hall, MD b, Allan D. Tachauer, MD a,,e

hicago, IL

oisChicago at Chicago, Chicago, IL

itical Care

ww.jcc journa l .o rgbasis or to assess parameters, which can potentially be assessed clinicallyor through other measures, such as capnometry [3].

Arterial blood gas analysis is a costly intervention and can lead toserious complications for the patient [3,4]. The current literature doesnot sufciently reect if a cost-efcient utilization of ABG analysisthrough signicant reduction of the number of ABG samples affects

patient outcome and patient safety. This study determines the effect ofreconsideration of the indications for ABG analysis, on patient outcomeand safety.

2. Methods

2.1. Data collection

The study was conducted at Weiss Memorial Hospital, an academicteaching hospital and afliate of the University of Illinois at Chicago,with a 16-bedmultidisciplinary ICU. A total of 300 patients were includ-ed in this retrospective data review. With the goal to provide excellentyet cost-efcient patient care, the indications to obtain an ABG samplein the ICU (including, for example, change in ventilator settings,respiratory or cardiac event, routine testing, metabolic event,postintubation and postextubation as well as preintubation andpreextubation, follow-up on abnormal test results, unreliable pulseoximetry data, and altered mental status) were reevaluated based onan evidence-based review of the literature betweenMarch and Novem-ber 2012. This change in the ICU model included intensivist-led teamdiscussion between attending physicians, resident physicians, and nurs-ing staff during rounds, assessing the indication to obtain an ABG foreach individual patient and individual clinical situations based on thequestion if the results from an ABG analysis would lead to a change inpatient management. The decision to obtain an ABG sample was made

medications including anesthetics and opiate-derived analgesics (al-prazolam, clonazepam, chlordiazepoxide, diazepam, hydromorphone,lorazepam, morphine, methadone, oxycodone, tramadol, fentanyl, mid-azolam, propofol, and remifentanil); readmissions to the ICUwithin theperiods mentioned above; complications from arterial puncture; anddemographic data including age, sex, Body Mass Index (BMI) as wellas cardiac and pulmonary comorbidities. Ventilator days and LOS inthe ICU were dened as primary outcome factors. Number ofreintubations, 30-day mortality, and complications after arterial punc-ture were secondary outcome measures. Subgroup analysis was per-formed in ventilated patients only (66 vs 60 patients in group 1 andgroup 2, respectively). Datawere extracted fromHorizon Physician Por-tal (McKesson Corporation, Chicago, IL) and MIDAS (version 8.1.4;MidasPlus Inc, Tuscon, AZ).

2.2. Statistical analysis

Statistical analysis was performed using SPSS version 21 (IBM Corp,Armonk, NY) and Microsoft Excel 2010 (Redmond, WA). After assess-ment of the normality of distribution of data collected with theKolmogorov-Smirnov test,Mann-WhitneyU testwas applied to analyzethe differences of ventilator days, LOS in the ICU, reintubation rates, andmedications. The t test was used to analyze patient age and BMI; andFisher exact test was applied to assess sex, 30-day mortality, cardiacand pulmonary comorbidities, and regression analysis; and Pearson

er p

438.e2 F.E. Blum et al. / Journal of Critical Care 30 (2015) 438.e1438.e5based on the assessment of the patient rather than routine daily ABGsampling, which included physical examination; ventilator parameters;and the awakening, breathing, coordination, delirium screening, and ex-ercise/early mobility assessment [6]. Before this change in practice wasintroduced in daily patient care, ABG analysis was commonly orderedby single health care providers with various levels of experience as amatter of routine and without an intensivist-led team assessment ofthe indication for ABG analysis based on the question if test results arelikely to lead to change in patient management. To determine the effectof this measure on patient outcome and safety, we conducted a retro-spective data review for the period between December 2011 and Febru-ary 2012 (group 1) and between December 2012 and February 2013(group 2). We included the number of ABG samples obtained in theICU; number of ventilator days; number of reintubations; length ofstay (LOS) in the ICU; 30-day mortality after admission to the ICU;

Fig. 1. Count of the number of ABG analysis pproduct correlation was performed. Data are presented as mean SD.This study was approved by the Institutional Review Board at

Vanguard Health Chicago Institutional Review Board/Tenet HealthCare. Waiver of consent was obtained.

3. Results

A total of 300 patients were included in the study (159 in group 1 and141 in group 2). Sixty-six patients in group 1 and 60 patients in group 2were ventilated in the ICU. The number of ABG samples obtained per pa-tientwas lower in group2 (all patients, 3.73.7; ventilated patients, 2.03 1.66) (Figs. 1 and 2) compared with group 1 (all patients, 5.5 4.7;ventilated patients, 6.12 5.9) (all patients, P b .001; ventilated patients,P b .001) (Figs. 2 and 3) (Table 1). A decrease of ABGs of more than 60%per patient was observed for ventilated patients.

atient for all patients in group 1 and group 2.

ient

438.e3F.E. Blum et al. / Journal of Critical Care 30 (2015) 438.e1438.e5The number of ventilator days per patient differed signicantlybetween groups (group 1, 6.46 5.04 vs group 2, 3.7 2.61; P =.004) (Mann-Whitney U test) (Fig. 3) (Table 1). Patients had a signif-icantly shorter LOS in the ICU in group 2 compared with group 1(ventilated patients: group 1, 8 5.6 vs group 2, 6 5.1; P =.036) (all patients: group 1, 6 4.7 vs group 2, 5 4.7 P = .02)(Mann-Whitney U test), whereas the LOS for all patients did not dif-fer between groups (group 1, 6 4.7 vs group 2, 5 4.7; P = .09)(Mann-Whitney U test) (Table 1) (Fig. 3). The total dose of propofolwas signicantly higher in group 2 compared with group 1 in all pa-

Fig. 2. Count of the number of ABG analysis per pattients as well as in ventilated patients only (group 1 ventilated pa-tients, 102.78 303.63 vs group 2, 235.02 449.64; P = .012)(group 1 all patients, 48.75 210.56 vs group 2, 31.04 148.47;P = .013) (Mann-Whitney U test). The total dose of lorazepam wassignicantly lower in group 2 compared with group 1 in all patientsand in ventilated patients only (group 1 ventilated patients, 81.59 440.38 vs group 2, 5.70 30.29; P = .008) (group 1 all patients,33.56 281.78 vs group 2, 0.212 1.69; P= .022) (Mann-Whitney

Fig. 3. Intensive care unit LOS in days, number of ABG analysis, and ventilator days for ven-tilated patients between December 2011 and February 2013.U test). Pearson product correlation reported a positive correlationbetween the LOS and ventilator days (Correlation Coefcient (CC)0.79, P b .001) as well as LOS and ABGs per patient (CC 0.532, P b.001). Furthermore, a positive correlation was reported betweenventilator days and ABGs per patient (CC, 0.522 P b .001). Bothgroups had similar demographics (Table 2), reintubation rates, com-plications from arterial puncture, and mortality at 30 days (Fisherexact test). Four patients in group 1 and 1 patient in group 2 werereadmitted to the ICU between December 2011 and February 2012and between December 2012 and February 2013, respectively.

in group 1 and group 2, in ventilated patients only.Body mass index was signicantly higher in group 2 comparedwith group 1, and a signicant difference in BMI was found as wellin a subgroup analysis of ventilated patients between group 1 andgroup 2 (group 1, 27 8.5 vs group 2, 29 8.9; P = .044) (all pa-tients: group 1, 25 7.1 vs group 2, 30 8.5 in ventilated patients;P = .007) (t test) (Table 2).

The total dose of alprazolam, clonazepam, chlordiazepoxide, di-azepam, hydromorphone, morphine, methadone, oxycodone,tramadol, fentanyl, midazolam, and remifentanil did not differ be-tween groups and subgroups of ventilated patients (P N .05 each)(Mann-Whitney U test).

4. Discussion

Our data indicate that improving costs by virtue of decreasing ABGutilization, based on the reassessment of indications to obtain ABG

Table 1Data primary outcome

Variable Group 1 Group 2 P

No. of ABG analysisVentilated patients 6.12 5.9 2.03 1.66 b .001All patients 5.5 4.7 3.7 3.7 b .001

ICU LOSVentilated patients 8 5.6 6 5.1 .04All patients 6 4.7 5 4.7 .09

Vent days 6.46 5.04 3.7 2.61 .004

Data are presented as mean SD.

In 1997, Pilon et al [9] suggested indications to obtain ABG samples

438.e4 F.E. Blum et al. / Journal of Critical Care 30 (2015) 438.e1438.e5including, for example, a change in ventilator settings.Since this study has been published, no further evaluation of indica-

tions for ABG analysis has been clearly reported. Furthermore, the valid-ity of these indications is questionable in current practice, as a change inventilator setting, for example, is not considered an absolute indicationsamples is safe and does not negatively impact patient outcome. A de-crease of ABG utilization was correlated with a decrease in ventilatordays and LOS in the ICU, allowing further improvement of costs for pa-tient care as well as improvement of safety and quality.

4.1. Reduction of unnecessary ABG analysis in the ICU

A signicant reduction of the number of ABGs of up tomore than 60%per patient in the ICU does not negatively impact patient outcome or pa-tient safety. The utilization of unnecessary testing has been addressed inthe literature and most recently in the Choosing Wisely campaign [7,8].However, the impact of a signicant reduction of ABG analysis on patientsafety and outcome in a closed ICU model has not been addressed yet.

Table 2Demographic characteristics

Variable Group 1 Group 2 P

No. ofpatients (n)

159 (66 patientson ventilator)

141 (60 patientson ventilator)

N/A

Sex (male/female)All 77/86 82/60 .08Ventilated 30/36 33/27 1.00

AgeAll 64 16.9 61 17.9 .082Ventilated 64 14.2 65 13.8 .903

BMI (kilograms per square meter)All 27 8.5 29 8.9 .044Ventilated 25 7.1 30 8.5 .007

Cardiac comorbidities (n)All 93 76 .565Ventilated 44 33 .264

Pulmonary comorbidities (n)All 60 51 .905Ventilated 30 27 1.000

Data presented as mean SD.for ABG analysis and is controversial in the current literature as wellas in routine clinical practice. Furthermore, the change of Positive End-Expiratory Pressure was found to have no signicant inuence of ABGanalysis results [10].

Other studies published also raise concern about commonly used in-dications for ABG analysis.

Pawson andDePriest [11], for example, found that ABGmeasurementdoes not necessarily need to precede extubation after a clinically success-ful spontaneous breathing trial. This nding was further supported by astudy published by Salam et al [12] in 2003, showing that ABG analysisresults do not change extubation decisions in more than 90% of cases.Furthermore, the role of pulse oximetry and capnometry as an alterna-tive for ABG analysis has to be considered [13]. Expiratory carbon diox-ide, for example, was found to correlate well with PaCO2 [13]; theexpiratory carbon dioxidePaCO2 gradient in patients without compro-mise in gas exchange, such as an underlying pulmonary pathology, forexample, is reported as 5mmHg [13]. More research is needed to estab-lish specic guidelines, in which cases, pulse oximetry and capnometrycan be used to replace conventional ABG analysis. Despite previousdata suggesting that indications for ABG analysis should be reevaluated,indications to obtain ABG samples should be based on clinical assess-ment and only if they are likely to change patient management [7,9].Melanson et al [3] have shown in 2007 that clinical routine is still acommon indication for ABG analysis, and 79% of ABG analysis resultswere as expected. In keeping with the new Society of Critical Care Med-icine Choosing Wisely campaign, furthermore, one of the efforts isbased in avoiding routine daily laboratory sampling [8].

These ndings strongly indicate the need to reassess commonlyused indications for ABG analysis and to dene solid clinical guide-lines for indications for this test. Our data suggest that a signicantreduction in ABG analysis is safe and does not negatively impact pa-tient outcome, and it may reduce the likelihood of potential compli-cations from arterial puncture. Our study was not primarilydesigned to detect complications from arterial puncture and com-pare them between groups; however, there were no documentedcomplications for either group. Further research needs to be doneon this particular topic with a larger patient population and aprospective approach on the assessment of complications of arterialpuncture, including minor complications such as vasospasm, whichis difcult to assess in retrospect. The number of pulmonary andcardiac comorbidities did not differ among patients in group 1 andgroup 2, indicating that a decrease of ABG analysis is safe and doesnot impair outcome in this high-risk patient population [14].

The observed signicant decrease of the LOS in the ICU in ventilatedpatients and in group 2 comparedwith group 1 aswell as the signicantdecrease of ventilator days in group 2 compared with group 1 is mostlikely amultifactorialnding. Our results show that there is a signicantcorrelation between LOS in the ICU and ventilator days, but at the sametime, the number of ABGs per patient was positively correlated withventilator days and LOS over time. This correlation in particularmay re-ect the indirect effect of the combination of measures taken to de-crease the number of ABG samples obtained per patient as part of anintensivist-led closed ICU model including changes of sedative medica-tion use. For example, the use of propofol instead of benzodiazepines forsedation has been shown to improve patient outcome by reducing theLOS in the ICU and the number of ventilator days [15].

Wang et al [7] reported in a study published in 2002 that educationof physicians and nursing staff has been shown to reduce frequent test-ing, such as frequent ABG analysis. Our approach mainly falls into thiscategory, as the application of a close clinical assessment of the patientin combination with team discussions about the indication to obtainan ABG in each particular case resulted in a decrease sampling of ABGsof up to more than 60% per patient, which in retrospect may indicatemuch of it prior was unnecessary. Hence, teamwork and frequentassessment of the patient at the bedside in an intensivist-led closedICU model seems to be the most effective way to reduce unnecessaryABG analysis. Other techniques to reduce frequent tests described inthe literature are electronic alerts for redundant testing in the computerordering system and changing in funding for tests. Furthermore, it canbe suggested that a feedback on change in ordering ABGs mightpositively enforce ordering behavior. Solomon et al [16] have shownthat a combination of interventions to reduce unnecessary testing ismore effective compared with a single measure.

Given that the presence of an arterial line has been described as themost important predictor of the number of ABG samples obtained fromthe patient [17], it is clear that attention must be paid to the utility oftesting rather than the ease with which a sample can be obtained. Theindication to obtain ABG analysis based on the clinical assessment ofthe patient may vary depending on the health care provider's experi-ence and level of training; therefore,more research is needed to developsolid guidelines and training programs for physicians and nursing staffto establish an equal standard of care for ABG analysis and to increasethe awareness of costs and potential consequences of unnecessary test-ing for the patient. Despite the large size of study population, limitationsof our assessment were conduction of the study at a single center andretrospective data review. Future multicenter studies are needed to de-velop new solid clinical practice guidelines leading to appropriate ABGsampling in the ICU to assure patient safety, further improve patientoutcome, and to simultaneously provide cost-efcient patient care.

5. Conclusion

Arterial blood gas analysis is oftentimes ordered as a routine, andABG results do not change patient management in most cases. This re-sults in increased risk for thepatient and increased costs for patient care.

A signicant decrease of the number of ABGs obtained in the ICUdoes not negatively affect patient safety, reduces the risk for complica-tions, and likely lowers the overall costs for patient care. A decrease ofthe number of ABGs can be done safely in a high-risk patient population.Further research is needed to develop guidelines for appropriate indica-tions for ABG analysis.

Acknowledgment

The authors would like to thank Kevin Baxter, RN, BS (senior dataanalyst, Weiss Memorial Hospital), and Elda Pourshahbaz (technical di-rector, Vascular Lab, Vascular Institute of Chicago at Weiss MemorialHospital), for excellent assistance in data acquisition and assessmentof data availability.

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line for arterial blood gas measurement in the intensive care unit decreases numbersand increases appropriateness of tests. Crit Care Med 1997;25(8):130813.

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438.e5F.E. Blum et al. / Journal of Critical Care 30 (2015) 438.e1438.e5

Reevaluation of the utilization of arterial blood gas analysis in the Intensive Care Unit: Effects on patient safety and pa...1. Introduction2. Methods2.1. Data collection2.2. Statistical analysis

3. Results4. Discussion4.1. Reduction of unnecessary ABG analysis in the ICU

5. ConclusionAcknowledgmentReferences