Download - Impact of 24-Hour In-House Intensivists on a Dedicated Cardiac Surgery Intensive Care Unit

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CARDIOTHORACIC ANESTHESIOLOGY:The Annals of Thoracic Surgery CME Program is located online at http://cme.ctsnetjournals.org.To take the CME activity related to this article, you must have either an STS member or anindividual non-member subscription to the journal.

mpact of 24-Hour In-House Intensivists on aedicated Cardiac Surgery Intensive Care Unit

anwal Kumar, MD, Ryan Zarychanski, FRCPC, Dean D. Bell, FRCPC,izwan Manji, PhD, FRCSC, Joel Zivot, FRCPC, Alan H. Menkis, FRCSC, andakesh C. Arora, PhD, FRCSC; on behalf of the Cardiovascular Health Research inanitoba Investigator Group

ardiovascular Health Research in Manitoba (CHaRM) Investigator Group, Cardiac Sciences Program, St. Boniface Generalospital/I.H. Asper Clinical Research Institute, Department of Hematology/Medical Oncology, Cancercare Manitoba, and Sections

f Hematology and Critical Care, University of Manitoba, Winnipeg, Manitoba, Canada

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Background. Intensive care unit (ICU) physician staff-ng models for cardiac surgery patients vary widely andorrelate poorly with outcomes. Clinical outcomes asso-iated with 24-hour, in-house intensivists working in aedicated post–cardiac surgical unit has not been previ-usly investigated. We sought to examine the safety andfficacy of such a model.Methods. A retrospective, propensity-matched, cohort

tudy of all patients undergoing a cardiac surgical pro-edure at a single tertiary center was performed. Theontrol cohort (n � 1,467) consisted of patients admittedo the traditional, mixed surgical intensive care unitSICU) from January 2005 to January 2007. The interven-ion cohort (n � 1,089) consisted of patients admitted to aewly created “hybrid” cardiac surgery ICU (CICU) fromanuary 2007 to January 2008, which was staffed by4-hour in-house consultant intensivists and a daytime,ast track cardiac anesthesiologist. The primary outcomesere blood product utilization, requirement for ventila-

ion, and ICU recidivism.

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esearch Institute, Winnipeg, Manitoba, R2H 2A7, Canada; e-mail:[email protected].

2009 by The Society of Thoracic Surgeonsublished by Elsevier Inc

Results. The proportion of patients in the CICU cohortho received transfused red blood cells was decreased

ompared with the SICU cohort (30.2% versus 42.3%, p <.001). Similar reductions in platelets and fresh frozenlasma were also observed. The CICU patients were less

ikely to arrive to the ICU intubated (43.7% versus 66.5%,< 0.001). There were no differences in postoperative

omplications. Overall hospital length of stay was re-uced in the CICU cohort by a median of 1 day (6 days

interquartile range, 5 to 8] versus 7 days [5 to 9], p <.001). Significant reductions in mortality and ICU recid-vism were not observed.

Conclusions. The current Manitoba CICU model of4-hour intensive care physician/cardiac anesthesiologisttaffing in postoperative cardiac surgery care is associatedith reduced transfusion of blood components, de-

reased requirement for mechanical ventilation, andhorter hospital length of stay.

(Ann Thorac Surg 2009;88:1153–61)
© 2009 by The Society of Thoracic Surgeons
ver the past 2 decades, the risk profile of patientsundergoing cardiac surgery has changed. Increas-

ngly, cardiac surgical operations are performed on olderatients with recent coronary syndromes, higher New Yorkeart Association classifications, lower left ventricular ejec-

ion fractions and cardiogenic shock preoperatively [1, 2].hese demographic changes within cardiac surgery aressociated with increases in mortality, intensive care unitICU) length of stay (LOS), and resource utilization [3–8].espite the increasing complexity of post–cardiac surgicalatients admitted to the ICU, the ideal intensive carerganizational framework has yet to be determined.

ccepted for publication April 17, 2009.

resented at the Forty-fifth Annual Meeting of The Society of Thoracicurgeons, San Francisco, CA, Jan 26–28, 2009.

ddress correspondence to Dr Arora, Cardiac Sciences Program, 369ache Ave, CR 3012, St Boniface General Hospital/I.H. Asper Clinical

Several centers have developed early extubation or “fast-rack” clinical pathways to minimize the need for intensiveare in appropriately selected patients [9–11]. Enders andolleagues [12] examined the safety of managing fast-trackatients in a post anesthesia recovery unit, thereby avoid-

ng ICU admission entirely. This study demonstrated that,n elective patients, direct admission to a post anesthesiaecovery unit was safe and effective [12]. To address thencreasing complexity of patients, other centers have cre-ted dedicated units for postoperative cardiac surgical care.ovick and coworkers [13] demonstrated that patients

dmitted to a specialized cardiac surgery recovery unit hadeductions in their composite complication rate after themplementation of an early extubation protocol. Two stud-es have addressed the efficacy of 24-hour consultant inten-ive care physician “intensivist” staffing models in a mixeddult ICU [14, 15]. We are unaware of any studies that havexamined this model of intensivist coverage in a dedicated
ardiac surgery ICU.
0003-4975/09/$36.00doi:10.1016/j.athoracsur.2009.04.070

http://cme.ctsnetjournals.org

mailto:[email protected]

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1154 KUMAR ET AL Ann Thorac Surg24-HOUR CARDIAC SURGERY ICU INTENSIVIST COVERAGE 2009;88:1153–61

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In our center, a dedicated cardiac surgery intensiveare unit was opened in January 2007 with a new “hy-rid” clinical coverage model that incorporated the un-

nterrupted presence of trained intensivists and an earlyxtubation pathway managed by cardiac anesthesiolo-ists. The hypothesis of our study was that care provided

n a hybrid dedicated cardiac surgery ICU staffed by4-hour in-house intensivists would be associated witheneficial clinical outcomes.

atients and Methods

ata Source and Collectionata for this study was complied in a retrospective

ashion using the Winnipeg Regional Health AuthorityCU database and the Saint Boniface General Hospital,ardiac Sciences Program surgical database (Winnipeg,anitoba). These databases have been prospectively

ollecting data from 1989 and 1995 respectively. Patientata was analyzed after approval from the research ethicsoard of the University of Manitoba.

escription of the Intensive Care Physiciantaffing Modelsaint Boniface General Hospital is one of two tertiaryare centers in the province of Manitoba and became theole provider of cardiac surgical procedures for theegion (�1.2 million patient referral base) in 2007. Before

ig 1. (A) Traditional mixed surgical inten-ive care unit staffing arrangement: an in-ouse certified intensivist, leading a housestaffomprised of junior residents of various medi-al backgrounds, provided daytime staffing.ighttime staffing was provided by a member

f this housestaff with on-call intensivistack-up. Patients were transferred to a step-own unit, followed by transfer to the generalard. (B) Cardiac surgery intensive care unit

CICU) staffing arrangement: upon leaving theperating room, patients followed one of tworacks. If they were a fast-track candidate, theardiac anesthesiologist would be the primaryaregiver. If patients required multisystemare, then the daytime intensivist would behe primary caregiver. Both consultants wouldign out to a nighttime certified intensivist.he next morning, patients would either beischarged directly to the ward or continuentensive care unit care. The step-down unitas eliminated in the CICU model.

007, patients were admitted to a traditional, mixed o

urgical intensive care unit (SICU) after cardiac surgerylongside patients from a variety of other surgical spe-ialties. Daytime coverage of the SICU consisted of aonsultant intensivist and a team of junior residentouse-staff from various disciplines. Overnight coverageas provided by an in-house junior resident with the

ntensivist providing home-call back-up. After ICU dis-harge, the patients were transferred to a step-down for

able 1. Fast-Track Extubation Criteriaa

emodynamically stable on minimal to no vasopressor/inotropic support

ore body temperature � 35.5°Cuff leak presentwake, able to obey commands, and able to maintain a patentairwaydequate pain controlressure support ventilation � 6ositive end-expiratory pressure � 5 cm H2Oraction of inspired oxygen � 0.50idal volume � 6 mL/kginute ventilation � 150 mL/kg

H � 7.30 to 7.50inor on-going coagulopathy causing bleeding was not acontraindication to extubationifficult airway was not a contraindication to early extubationif patient met above criteria

Anesthetic management was tailored to meet these criteria within theperating room or shortly thereafter within the intensive care unit.

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1155Ann Thorac Surg KUMAR ET AL2009;88:1153–61 24-HOUR CARDIAC SURGERY ICU INTENSIVIST COVERAGE

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ntermediate care, before the general cardiac surgicalard (Figure 1A). In the step-down unit, patients could

etain invasive hemodynamic monitoring and receiveestricted doses of a limited number of inotropicgents.

reation of the Hybrid Cardiac Surgery Intensiveare Unitfter regional restructuring in 2007, surgical volume

able 2. Baseline Patient Characteristics in the Unmatched C

SIC

emographicsAge, years, mean � SDFemale, nBody surface area, m2

APACHE II scorea

Smoking, nDiabetes mellitus, nFamily history of premature CAD, nDyslipidemia, n 1,Hypertension, n 1,Previous cerebrovascular event, nChronic obstructive pulmonary disease, nChronic renal insufficiency, nPeripheral vascular disease, n

ardiac historyPrevious MI, nPrevious MI � 21 days, nPrevious MI � 21 days, nCCS class I–II, nCCS class III–IV, n 1,Preoperative ß-blocker use, n 1,Preoperative acetylsalicylic acid use, n 1,Preoperative ACE inhibitor use, nCardiogenic shock, nLVEF � 35%, n 1,LVEF � 35%, nperative detailsPreoperative hemoglobin, g/L, mean � SD 1Reoperation, nNonemergent, n 1,Emergent, nCABG, n 1,CABG � valve, nValve only, nOther, nIntra-aortic balloon pump used, nIMA used (all cases), n 1,Cross-clamp time, minutes, mean � SDCPB time, minutes, mean � SD 1

The Acute Physiology and Chronic Health Evaluation (APACHE II) was uf scores for this test is 0 to 71.

CE � angiotensin-converting enzyme; CABG � coronary artery byardiovascular Society; CICU � cardiac surgery intensive care unitVEF � left ventricular ejection fraction; MI � myocardial infarction

ncreased from approximately 700 to 1100 cardiac surgical m

ases per year. A dedicated cardiac surgery intensive carenit (CICU) was created to accommodate this increase;

he total number of available beds in this new unitemained limited to 8–10, primarily due to resourcevailability. In addition, access to over-flow post anesthe-ia recovery beds, as others have described [12], was notvailable. A hybrid “fast-track” approach to postopera-ive patient care was therefore developed.

The decision to fast-track a patient postoperatively was

� 1,467) CICU (n � 1,089) p Value

10.8 64.3 � 11.4 0.5325.6%) 283 (26%) 0.84

0.24 1.99 � 0.25 0.024.4 14.3 � 4.9 0.008

67.2%) 714 (65.7%) 0.4430%) 361 (33.2%) 0.0848.6%) 521 (48%) 0.7771.5%) 810 (74.6%) 0.0870.2%) 781 (71.9%) 0.335.8%) 58 (5.3%) 0.629.8%) 94 (8.7%) 0.342.9%) 27 (2.5%) 0.4931.8%) 213 (19.6%) �0.0001

54.9%) 583 (53.5%) 0.4851.2%) 306 (52.5%) 0.6548.8%) 277 (47.5%)24.1%) 288 (26.5%) �0.000175.9%) 801 (73.5%)75.4%) 827 (76.9%) 0.4184.4%) 929 (86.3%) 0.1757.1%) 681 (63.3%) 0.0021.8%) 15 (1.4%) 0.4789.0%) 932 (89.9%) 0.4711.0%) 105 (10.1%)

18.9 134.3 � 18.7 0.883.6%) 57 (5.3%) 0.0494.9%) 1,025 (94.2%) 0.455.1%) 63 (5.8%)73.6%) 763 (70.1%) 0.018.2%) 115 (10.6%)11.1%) 107 (9.8%)7.1%) 104 (9.6%)5.2%) 33 (3.1%) 0.00978.3%) 829 (76.1%) 0.19

41 69.6 � 42.9 �0.000154.7 106.3 � 56.2 �0.0001

assess patients on the intensive care unit (ICU) admission day; the range

graft surgery; CAD � coronary artery disease; CCS � CanadianPB � cardiopulmonary bypass; IMA � internal mammary artery;

ICU � traditional mixed surgical intensive care unit.

ohort

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onsultation between the surgeon and the cardiac anes-hesiologist. A dedicated CICU cardiac anesthesiologist,ho was free from all other clinical and administrativeuties, would direct care of patients suited for earlyxtubation (fast-track candidates [10]) during daytimeoverage (08h00–16h00). The criteria for extubation ofast-track candidates is summarized in Table 1. Patients

able 3. Baseline Patient Characteristics in the Matched Coho

SIC

emographicsAge, years, mean � SDFemale, n 2Body surface area, m2

APACHE II scorea

Smoking, n 6Diabetes mellitus, n 3Family history of premature CAD, n 4Dyslipidemia, n 7Hypertension, n 6Previous cerebrovascular event, nChronic obstructive pulmonary disease, nChronic renal insufficiency, nPeripheral vascular disease, n 1

ardiac historyPrevious MI, n 5Previous MI � 21 days, n 2Previous MI � 21 days, n 2CCS class I–II, n 2CCS class III–IV, n 7Preoperative ß-blocker use, n 7Preoperative acetylsalicylic acid use, n 8Preoperative ACE inhibitor use, n 5Cardiogenic shock, nLVEF � 35%, n 8LVEF � 35%, nperative detailsPreoperative hemoglobin, g/L, mean � SD 1Reoperation, nNonemergent, n 8Emergent, nCABG, n 6CABG � valve, nValve only, nOther, nIntra-aortic balloon pump used, nIMA used (all cases), n 7Cross-clamp time, minutes, mean � SDCPB time, minutes, mean � SD 1

The Acute Physiology and Chronic Health Evaluation (APACHE II) was uf scores for this test is 0 to 71.

CE � angiotensin-converting enzyme; CABG � coronary artery byardiovascular Society; CICU � cardiac surgery intensive care unitVEF � left ventricular ejection fraction; MI � myocardial infarction

ho were not fast-track candidates (i.e. difficult airway, t

eep hypothermic arrest, significant pharmacologicalupport, or ongoing bleeding due to coagulopathy), wereanaged by an intensivist within the same ICU. In

ddition to this daytime hybrid approach, the dedicatedICU model employed 24-hour, seven days a week

n-house intensivist coverage. At 18h00, the daytimentensivist and cardiac anesthesiologist signed over care

� 933) CICU (n � 933) p Value

� 10.8 64.5 � 11 0.955.7%) 234 (25.1%) 0.75� 0.24 2.0 � 0.25 0.71� 4.1 14.3 � 4.8 0.516.6%) 618 (66.2%) 0.882.3%) 306 (32.8%) 0.809.1%) 451 (48.3%) 0.755.5%) 699 (74.9%) 0.790.8%) 667 (71.5%) 0.76.7%) 51 (5.5%) 0.46.6%) 84 (9%) 0.74.6%) 24 (2.6%) 1.009.9%) 189 (20.3%) 0.86

3.9%) 521 (55.8%) 0.493.9%) 267 (51.2%) 0.406.1%) 254 (48.8%)3.3%) 221 (23.7%) 0.836.7%) 712 (76.3%)6.1%) 719 (77.1%) 0.627.1%) 813 (87.1%) 1.001.8%) 579 (62.1%) 0.92.2%) 12 (1.3%) 0.837.6%) 811 (86.9%) 0.86.2%) 93 (10%)

� 50.2 107.5 � 52.9 0.35.8%) 36 (3.9%) 0.95.5%) 898 (96.2%) 0.42.5%) 35 (3.8%)3.3%) 691 (74.1%) 0.97.9%) 88 (9.4%)0%) 94 (10.1%).9%) 60 (6.4%).7%) 29 (3.1%) 0.589.5%) 746 (80%) 0.82� 39.3 71.5 � 42.2 0.7� 50.2 107.5 � 52.9 0.35

o assess the patients on their intensive care unit admission day; the range

graft surgery; CAD � coronary artery disease; CCS � CanadianPB � cardiopulmonary bypass; IMA � internal mammary artery;

ICU � traditional mixed surgical intensive care unit.

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o an incoming intensivist who remained in-house, until

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8h00 the following day. The nighttime intensivist servedhe same functional role as the daytime intensivist. Theollowing morning, patients were either discharged di-ectly to the ward or signed over to the daytime inten-ivist for continued CICU care. This model furthertreamlined patient care by eliminating the step-downnit and allowing direct transfer from the CICU to theard (Figure 1B).

tudy Population and Study Variableso minimize selection bias and maximize generalizabil-

ty, the study included all patients undergoing a cardiacurgical procedure regardless of co-morbidity or urgencytatus. The SICU control cohort consisted of consecutiveardiac surgery patients admitted to the traditional ICUwo years before consolidation in 2007 (January 2005 toanuary 2007). The CICU cohort consisted of consecutiveatients admitted to the new CICU over the first year ofperation (January 2007 to January 2008). Variables as-essed in all patients included baseline demographics,elevant co-morbidities, laboratory parameters, and op-rative details, in addition to ICU and hospital outcomes.tandard Society of Thoracic Surgeons and ICU clinicalefinitions were used for operative characteristics andostoperative ICU and hospital outcomes. ICU outcomesere complete for 100% of the patients.

utcomes Measuredo determine the safety and efficacy of the newly createdICU, requirement for mechanical ventilation, allogeneiclood product utilization, and ICU recidivism were therimary end-points as they have been shown to haveegative prognostic impact on patients undergoing cardiacurgery [11, 16–18]. Recidivism was defined as readmis-ion to the ICU during the same hospital stay [19].econdary end-points included common postoperative

able 4. Propensity Matched Postoperative Outcomes Related

SICU

CU outcomesMechanical ventilation on admission, n 620 (66.5%)Median ICU LOS, days (IQR) 0.96 (0.82, 1.83ICU recidivism, n 38 (4.07%)ICU mortality, n 14 (1.50%)

ostoperative outcomeReoperation for bleeding, n 61 (6.54%)Perioperative myocardial infarction, n 6 (0.64%)Postoperative atrial fibrillation, n 250 (26.8%)Postoperative renal dysfunction, n 70 (7.50%)Postoperative cerebrovascular event, n 16 (1.71%)Postoperative infections (all), n 63 (6.75%)Median hospital LOS, days (IQR) 7.0 (5.0, 9.0)Thirty-day mortality, n 20 (2.14%)

I � confidence interval; CICU � cardiac surgery intensive care unit;f stay; SICU � traditional, mixed surgical intensive care unit.

omplications, ICU and hospital LOS, and mortality. u

tatistical Analysisata are presented as mean � SD or median and

orresponding interquartile range where appropriate.aseline characteristics of patients in both ICU cohortsere compared using Student’s T test for continuous

ariables, or Chi Square testing for categorical variables.CU mortality and 30-day mortality were both expresseds a proportion and as an odds ratio (OR) with 95%onfidence intervals (95% CI). An odds ratio of less thansignifies decreased mortality in the CICU model com-ared to the former SICU model of care. The median ICUnd hospital LOS were compared using the Wilcoxonank-sum test. Categorical outcomes were comparedsing the Chi square test. All reported p values are-tailed, with alpha � 0.05.

As it was not possible to randomly assign the model ofCU care, a propensity analysis was undertaken to ac-ount for potential confounding factors and case selec-ion biases. Methodology and the reporting of these dataere based on a previous publication, which utilizedropensity methods [20]. A propensity score derived

rom clinical and laboratory data was developed usingultivariable logistic regression. These variables in-

luded demographic data (age, gender, body surfacerea, and Acute Physiology and Chronic Health Evalua-ion [APACHE] II score), and baseline co-morbiditiesncluding diabetes, chronic renal insufficiency, chronicbstructive pulmonary disease, and peripheral vascularisease. Cardiac history (CCS angina classification, pre-ious myocardial infarction, left ventricular ejection frac-ion grade, cardiogenic shock, and preoperative acetyl-alicylic acid, beta-blocker, and ACE inhibitor use), andperative data (preoperative hemoglobin, reoperation,urgical status, surgical procedure, intra-aortic balloonump use, and cardiopulmonary bypass [CPB] and crosslamp times) were also included. Propensity scores were

e Model of ICU Care

CICU p Value Odds Ratio (95% CI)

408 (43.7%) �0.001 0.39 (0.33, 0.47)0.98 (0.85, 1.93) 0.02 —

29 (3.11%) 0.26 0.76 (0.46, 1.24)12 (1.29%) 0.69 0.86 (0.39, 1.86)

65 (6.97%) 0.71 1.07 (0.75, 1.54)8 (0.86%) 0.59 1.34 (0.46, 3.87)

243 (26.1%) 0.71 0.96 (0.78, 1.18)78 (8.36%) 0.49 1.12 (0.80, 1.57)18 (1.93%) 0.73 1.13 (0.57, 2.25)58 (6.22%) 0.64 0.92 (0.63, 1.32)6.0 (5.0, 8.0) �0.001 —16 (1.71%) 0.50 0.80 (0.41, 1.55)

U � intensive care unit; IQR � interquartile range; LOS � length

to th

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sed to match patients in the CICU cohort with like

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atients in the SICU cohort. A greedy matching proce-ure selected match pairs initially identical to 5 decimallaces of probability [21]. If no match existed at 5 decimallaces, matching would occur at 4 decimal places and son. If no match existed at 1 decimal place then that patientas excluded from the study. The high matching successas designed to reduce the possibility of introducing sys-

ematic biases. Statistical analyses were conducted by usingAS version 9.1 (SAS Institute, Cary, NC).

esults

aseline Characteristics

reoperative baseline demographics, preexisting medicalonditions and operative details within the unmatchedtudy populations are listed in Table 2 (n � 1,467 patientsn the SICU model and n � 1,089 patients in the CICU

odel). Several preoperative differences within the un-atched populations existed. There was a small but

linically irrelevant difference in body surface area be-ween cohorts. The CICU cohort had a lower proportionf patients with peripheral vascular disease and CCSlassification of III-IV. Preoperative acetylsalicylic acidnd beta-blocker use was similar between cohorts; how-ver a greater proportion of patients were on an ACEnhibitor preoperatively in the CICU cohort. Operativergency status was similar, and minor variation in theistribution of the surgical procedures existed. A smallerroportion of the CICU cohort required the use of an

ntra-aortic balloon pump. CPB and cross-clamp timesere also shorter in the CICU cohort. APACHE II scoresere statistically lower in the CICU cohort.

aseline Characteristics After Propensity Matching

ropensity matching was successful for 933 (85.7%) of089 patients admitted to the CICU. After matching, the

ig 2. A significant reduction in the proportion of patient receivingacked red blood cells (PRBCs), platelets, and fresh frozen plasmaFFP) was observed in the cardiac surgery intensive care unit cohortsolid bars) compared with the surgical intensive care unit cohort

topen bars).

reviously described differences were eliminated in theatched study populations (Table 3). The propensityatched populations were used for all subsequent out-

ome comparisons.

utcomesn the CICU cohort, there was a significant reduction inhe requirement for mechanical ventilation on admissiono the ICU (Table 4). In addition there was a substantialecrease in the proportion of patients transfused alloge-eic blood products in the CICU cohort (Figure 2). Theroportion of patients transfused packed red blood cells

PRBCs) decreased from 42.3% in SICU to 30.2% in theatched CICU cohort (OR 0.59 [95%CI 0.49 to 0.71], p �

.001). Likewise, fewer CICU patients received platelet10.0%vs.13.7%, OR 0.70 [95%CI 0.52–0.93], p � 0.01) orresh frozen plasma (14.5%vs.26.8%, OR 0.46, [95%CI.37–0.58], p � 0.001) transfusions. Furthermore, in thoseatients who were transfused, there was a decrease in the

otal number of units utilized within the CICU cohortdata not shown). The elimination of the step-down unitith direct ICU-to-ward transfers in the CICU model didot alter ICU recidivism rates (Table 4).With respect to the secondary outcomes, there were no

ignificant differences observed between the cohorts forommon postoperative events (reoperation for bleeding,erioperative myocardial infarction, atrial fibrillation, re-al dysfunction, stroke, and infection rates). ICU mortal-

ty and 30-day mortality within the CICU cohort were notignificantly reduced (Table 4). Though there was noifference in ICU LOS, the median hospital LOS wasignificantly shorter in the CICU cohort (Table 4).

omment

n this study the implementation of a hybrid CICU modelor postoperative cardiac surgery was associated withignificant reductions in mechanical ventilation, alloge-eic blood transfusion, and hospital LOS. Increases in

CU recidivism were not observed despite elimination ofhe step-down unit and direct transfer to a postoperativeard in the CICU cohort. The authors believe the afore-entioned reductions are important as they have been

inked to adverse outcomes in postoperative cardiacurgery patients [16, 18, 22]. To our knowledge, this typef staffing model has not been previously investigated.The implementation of an early extubation protocol to

xpedite care is a cost saving measure employed in arowing number of centers [11, 12]. Our hybrid model,hich employs a cardiac anesthesiologist to manage the

ow-risk patients, facilitated a lower dependence on me-hanical ventilation when leaving the operating room.owever this ideology cannot be universally imple-ented in all patients as cardiac surgical procedures now

xtends to elderly, higher risk patients with increasingrequency [1, 2]. Therefore physicians with formal criticalare training, versed in the latest concepts of “maximalupportive technologies” and therapies [23], are integralo a multidisciplinary team required for effective care of
hese complex patients. Familiarity and adherence with

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he evidence-based literature on blood conservationtrategies is an example of the benefits of this approach.

Within our hybrid model, familiarity and adherenceith the evidence-based blood conservation strategiesas evident by the significant reduction in transfusion

ates. Since 2001, the average proportion of patientsransfused red cell units at our institution was approxi-

ately 45%. Since the implementation of the CICU, thatroportion has dropped to slightly over 30%; whichepresents a relative risk reduction of nearly 30%. Thiseduction is not only a cost savings, but may also impactatients’ short and long-term outcomes [16, 24].Although our study was not powered, or designed to

etect a difference in 30-day mortality with respect to redell transfusions, reduced transfusions may partially ex-lain the trends in reductions seen in ICU (1.29% vs..50%) and 30-day (1.71% vs. 2.14%) mortality within theICU cohort as compared to the SICU cohort. Despitearious perioperative strategies to reduce blood transfu-ions, some patients will continue to require blood prod-cts. Having dedicated intensivists, with expertise in

ransfusion management, may ultimately benefit theatient.The current recommendation by the Society of Critical

are Medicine for Level I critical care centers is to have4-hour in-house certified intensivist staffing [25].hough 24-hour staffing may be associated with im-rovements in care processes, staffing satisfaction, andeductions in ICU complication rates [15], this issue hasot been investigated in the postoperative cardiac sur-ery ICU setting. It is well appreciated that the first 24ours of care after cardiac surgery are the most important

or the majority of patients [26]. Guru et al. examined theature of preventable deaths in patients undergoingoronary artery bypass surgery and revealed that 61% ofeaths were related to ICU problems, including 35% ofeaths due to improper diagnosis of life threateningvents [27]. We speculate that the CICU intensivist staff-ng model could potentially limit these errors byromptly recognizing and managing serious issues thatccur “after-hours.” Kogan et al. in their study found thatespiratory issues (43.4%), atrial fibrillation (13.2%), andenal insufficiency (11.3%) were the primary cause forCU recidivism in fast-track patients [28]. These insidiousssues can be promptly dealt with by experienced in-ouse intensivist coverage. In addition, in-house inten-ivist staffing may allow for continual optimization ofatients, thus preparing them for ICU discharge the nextorning. This is supported by our data, which shows no

hange in ICU recidivism despite the elimination of thetep-down unit.

The LOS in our traditional SICU was similar to thoseeported by others [1, 10]. After implementation of theew CICU model, the overall hospital LOS was reducedy one full median day. Reductions in ICU LOS were noteen and is likely a partial reflection of our currentnstitutional policy mandating that all postoperative car-
iac surgery patients stay the first night in the ICU. t
imitationsrandomized control trial comparing the two ICU careodels was not possible. As such, an observational

efore-and-after study design, as used by others [12, 13,5], was utilized to address the question. Employing aropensity score analysis allowed for the examination oflarge patient cohort (n � 2,556), matched on more than

0 clinical, physiological, and surgical variables. Thispproach permits valid comparison despite the lack of ariori patient randomization and should serve to botheduce variability and increase overall precision of out-ome estimates.

It is possible that changes in overall care occurred overime, which were unrelated to the ICU models. Duringhe study period (2005–2007) between both models ofare, there were no major operative, ICU, or anestheticreatment or policy changes that were implemented. Thentra-operative anesthetic management and the extuba-ion guidelines remained similar within both models ofare. The findings from the Transfusion Requirements inritical Care trial formed the basis for our institution’seneral transfusion practices and did not change

hroughout the study period [29]. Furthermore, the find-ngs from the BART trial had limited effect on our study30]. Though all patients received some form of anti-brinolytic therapy, only high-risk patients in our centereceived aprotinin. The majority of patients receivedither e-aminocaproic acid or tranexamic acid as thenti-fibrinolytic of choice. Up until the withdrawal fromhe market, late October 2007 (at the end of our studyeriod), the use of aprotinin at our institution remainedimilar throughout the years.

Although the major change being the staffing model,he routine day-to-day ICU patient management had nothanged and was carried out by nursing staff and alliedealth individuals that were familiar with postoperativeardiac cases. One variable that we were unable toontrol for was the addition of cardiac surgeons andardiac anesthesiologists with formal critical care train-ng that routinely staffed the new CICU. The presence ofhese highly qualified personnel may have generated aulture of more tenacious observance to process of carerotocols on a 24-hour/7 days a week basis.We did not capture reintubation of patients within either

are model. This would be useful data to examine given thateintubation has been linked with increased morbidity andortality [22]. Similar ICU length of stays between the twoodels indirectly suggests that reintubation was probably

ot significantly greater in the CICU model.A 1-day shorter hospital LOS, in the absence of an

ppreciable change in the duration of ICU LOS may alsoe due to changes in patient care over time. The use ofniversal telemetry monitoring on all postoperative pa-

ients (a current feature in our institution), rather thanimiting monitoring to patients in the step-down unit,

ay have had an impact and will be the subject of futuretudy.

In conclusion, a dedicated hybrid cardiac surgery in-
ensive care unit, which employs an intensive physician

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taffing model comprised of highly qualified personnelell-versed in both multisystem and fast-track ap-roaches, is associated with reductions in the need forostoperative mechanical ventilation, blood component

ransfusion, and hospital length of stay. Further studiesre needed to ascertain the cost-effectiveness of thisodel and to identify which aspects of this new para-

igm are responsible for the most significant improve-ent in clinical outcomes.

he authors would like to thank Verna Tribula for her endlessfforts in maintaining the cardiac surgical database. We wouldlso like to thank Brett Hiebert for his invaluable assistance inhe amalgamation of the ICU and surgical data.

eferences

1. Abramov D, Tamariz MG, Fremes SE, et al. Trends incoronary artery bypass surgery results: a recent, 9-yearstudy. Ann Thorac Surg 2000;70:84–90.

2. Ferguson TB, Hammill BG, Peterson ED, DeLong ER, GroverFL. A decade of change—risk profiles and outcomes forisolated coronary artery bypass grafting procedures, 1990–1999: a report from the STS National Database Committeeand the Duke Clinical Research Institute. Society of ThoracicSurgeons. Ann Thorac Surg 2002;73:480–90.

3. Bucerius J, Gummert JF, Walther T, et al. Predictors of pro-longed ICU stay after on-pump versus off-pump coronaryartery bypass grafting. Intensive Care Med 2004;30:88–95.

4. Atoui R, Ma F, Langlois Y, Morin JF. Risk factors forprolonged stay in the intensive care unit and on the wardafter cardiac surgery. J Card Surg 2008;23:99–106.

5. Simon C, Luciani R, Capuano F, et al. Mild and moderaterenal dysfunction: impact on short-term outcome. Eur J Car-diothorac Surg 2007;32:286–90.

6. Scott BH, Seifert FC, Grimson R, Glass PS. Octogenariansundergoing coronary artery bypass graft surgery: resourceutilization, postoperative mortality, and morbidity. J Cardio-thorac Vasc Anesth 2005;19:583–8.

7. Rosenfeld R, Smith JM, Woods SE, Engel AM. Predictors andoutcomes of extended intensive care unit length of stay inpatients undergoing coronary artery bypass graft surgery.J Card Surg 2006;21:146–50.

8. Nakasuji M, Matsushita M, Asada A. Risk factors for pro-longed ICU stay in patients following coronary artery bypassgrafting with a long duration of cardiopulmonary bypass. JAnesth 2005;19:118–23.

9. Cheng DC, Karski J, Peniston C, et al. Early tracheal extu-bation after coronary artery bypass graft surgery reducescosts and improves resource use. A prospective, random-ized, controlled trial. Anesthesiology 1996;85:1300–10.

0. Cheng DC, Karski J, Peniston C, et al. Morbidity outcome inearly versus conventional tracheal extubation after coronaryartery bypass grafting: a prospective randomized controlledtrial. J Thorac Cardiovasc Surg 1996;112:755–64.

1. van Mastrigt GA, Maessen JG, Heijmans J, Severens JL,Prins MH. Does fast-track treatment lead to a decrease ofintensive care unit and hospital length of stay in coronaryartery bypass patients? A meta-regression of randomizedclinical trials. Crit Care Med 2006;34:1624–34.

2. Ender J, Borger MA, Scholz M, et al. Cardiac surgeryfast-track treatment in a postanesthetic care unit: six-monthresults of the Leipzig fast-track concept. Anesthesiology
2008;109:61–6.
3. Novick RJ, Fox SA, Stitt LW, et al. Impact of the opening ofa specialized cardiac surgery recovery unit on postoperativeoutcomes in an academic health sciences centre. Can JAnaesth 2007;54:737–43.

4. Arabi Y, Alshimemeri A, Taher S. Weekend and weeknightadmissions have the same outcome of weekday admissionsto an intensive care unit with onsite intensivist coverage.Crit Care Med 2006;34:605–11.

5. Gajic O, Afessa B, Hanson AC, et al. Effect of 24-hourmandatory versus on-demand critical care specialist pres-ence on quality of care and family and provider satisfactionin the intensive care unit of a teaching hospital. Crit CareMed 2008;36:36–44.

6. Kuduvalli M, Oo AY, Newall N, et al. Effect of perioperativered blood cell transfusion on 30-day and 1-year mortalityfollowing coronary artery bypass surgery. Eur J CardiothoracSurg 2005;27:592–8.

7. Gaudino M, Girola F, Piscitelli M, et al. Long-term survivaland quality of life of patients with prolonged postoperativeintensive care unit stay: unmasking an apparent success.J Thorac Cardiovasc Surg 2007;134:465–9.

8. Koch CG, Li L, Duncan AI, et al. Morbidity and mortality riskassociated with red blood cell and blood-component trans-fusion in isolated coronary artery bypass grafting. Crit CareMed 2006;34:1608–16.

9. Cohn WE, Sellke FW, Sirois C, Lisbon A, Johnson RG.Surgical ICU recidivism after cardiac operations. Chest 1999;116:688–92.

0. Zarychanski R, Doucette S, Fergusson D, et al. Early intra-venous unfractionated heparin and mortality in septic shock.Crit Care Med 2008;36:2973–9.

1. Parsons L. Reducing bias in a propensity score matched-pairsample using greedy matching techniques. Cary, NC: SASInstitute, 2001.

2. Epstein SK, Ciubotaru RL, Wong JB. Effect of failed extuba-tion on the outcome of mechanical ventilation. Chest 1997;112:186–92.

3. Katz NM. The emerging specialty of cardiothoracic surgicalcritical care: the leadership role of cardiothoracic surgeonson the multidisciplinary team. J Thorac Cardiovasc Surg2007;134:1109–11.

4. Koch CG, Li L, Duncan AI, et al. Transfusion in coronaryartery bypass grafting is associated with reduced long-termsurvival. Ann Thorac Surg 2006;81:1650–7.

5. Haupt MT, Bekes CE, Brilli RJ, et al. Guidelines on criticalcare services and personnel: recommendations based on asystem of categorization of three levels of care. Crit CareMed 2003;31:2677–83.

6. St Andre AC, DelRossi A. Hemodynamic management ofpatients in the first 24 hours after cardiac surgery. Crit CareMed 2005;33:2082–93.

7. Guru V, Tu JV, Etchells E, et al. Relationship betweenpreventability of death after coronary artery bypass graftsurgery and all-cause risk-adjusted mortality rates. Circula-tion 2008;117:2969–76.

8. Kogan A, Cohen J, Raanani E, et al. Readmission to theintensive care unit after “fast-track” cardiac surgery: riskfactors and outcomes. Ann Thorac Surg 2003;76:503–7.

9. Hebert PC, Wells G, Blajchman MA, et al. A multicenter,randomized, controlled clinical trial of transfusion require-ments in critical care. Transfusion Requirements in CriticalCare Investigators, Canadian Critical Care Trials Group.N Engl J Med 1999;340:409–17.

0. Fergusson DA, Hebert PC, Mazer CD, et al. A comparison ofaprotinin and lysine analogues in high-risk cardiac surgery.
N Engl J Med 2008;358:2319–31.

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R NEVIN M. KATZ (Washington, DC): I want to congratulater Kumar on an excellent presentation and bringing this subject

o our meeting. Clearly, it is important to recognize that cardio-ascular thoracic critical care has emerged as a specialty, be-ause the physiology, the procedures, and the potential compli-ations in this group of patients are truly unique to medicalractice. With the changes in available surgical manpower and

he increasing complexity of management, cardiovascular tho-acic critical care is now carried out by a multidisciplinary team,hich you have very well described. It is very important that

ardiothoracic surgeons have a leadership role on this team, andcongratulate you for making that part of your paradigm.One of the challenges in cardiovascular critical care is the

arly diagnosis and management of acute kidney injury. I noticehat you did not have an important change in this, and I amondering, since this is an ongoing challenge, how you areoing to address this.Again, I want to congratulate you. I think this is a very

mportant area that we should be developing within thoracicurgery, and, I might say, thoracic surgeons over the last severalears have played a major role in developing this specialty.hank you.

R KUMAR: Thank you for your comments. Our group agreeshat tailored and focused ICU care postoperatively is essential inhe modern era of cardiac surgery. As patient risk profileshange and surgical procedures increase in complexity, havingndividuals who understand the operation and are able toeliver appropriate ICU care is crucial. Our hybrid CICU modelddresses this by having cardiac care specialists formallyrossed-trained in critical care medicine delivering 24-hourn-house care.

With respect to your comment on acute kidney injury, it ismportant to recognize that individuals with renal impairmentfter surgery have a worse prognosis. With such a low event ratend the limited number of study patients, it is difficult to show aeduction in renal dysfunction after surgery. We are currentlyerforming a post hoc analysis of high-risk patients, including

hose with renal impairment preoperatively and postopera-ively, to see the extent of improvement in outcomes with this

odel of care. Having certified intensivists delivering 24-hourultisystem care allows for early diagnosis and intervention of

nsidious postoperative complications, such as pending renalmpairment or cardiac dysfunction. In addition, with critical careraining, decisions to utilize maximal supportive therapies, suchs renal replacement therapy, can be delivered at anytimeuring the day.

R VASSYL A. LONCHYNA (Chicago, IL): Doctor Kumar, aery nice presentation and my congratulations to the group at St.oniface. Also I would like to recognize and greet Dr Barwinsky,ho created your surgical unit, your retired former chief.As a surgeon who now practices critical care, I am very

nterested in your findings and the way you have rededicatedour unit along the various tracks there. You have rightfully
tated at the end that one of the weaknesses is the fact that you h
on’t have the data such as the hours to extubation, because thatertainly would tell us the impact of your intervention in thentensive care unit, whether the fast track or the more complexrack. Granted, also, we know that we have very excellent nursesn the cardiac units that also contribute significantly to thentervention of the protocols that allow for early extubation.

I would like to also just present another option for a hybridnit, and that would be that of an electronic ICU. In thehicagoland area, we have at least three major medical hospital

ystems that have this electronic ICU, which adds another layerf care in overseeing the various problems in ICUs, and thisould perhaps add greater safety to taking care of patients in theostoperative period. Congratulations again for a beautifulresentation.

R KUMAR: Thank you for your comments. With respect todditional early extubation data, that is a deficiency in oururrent database system, which we are looking into. Althoughe are unable to give a true denominator of potential fast-track

andidates, given that the majority of patients are actuallyxtubated intraoperatively, the proportion fast-tracked is in factrobably higher than recorded.Regarding the two tracks of ICU care, since our study was

nclusive of all patients undergoing surgery, our results can beeneralized and not limited to isolated CABG patients as inrevious studies. At this point, we are currently separating the

wo cohorts to further analyze the impact of our hybrid model ofare. At our institution, fast-track anesthesia is more than arocess, it’s a mindset of our anesthesiologists. If a patient isealthy before the operation, receives a technically sound sur-ery, they should be healthy on recovery, and are treated asuch. In addition, because of the hybrid model with the presencef a cardiac anesthesiologist in the ICU, there is a continuity ofnesthetic management that flows from the operating room tohe ICU.

As you mentioned, having dedicated critical care nursesamiliar with post–cardiac surgical patients is essential in devel-ping an effective and efficient ICU model. Nursing backgroundnd experience with cardiac patients was similar between thewo cohorts; therefore, this was not a significant confoundingactor within the study.

With regard to an electronic ICU, as our institution is the onlyeferral center within the district, employing an electronic modelould be of less benefit in our system. Additionally, although an

lectronic ICU is potentially more efficient, we feel the presencef a bedside intensivist 24-hours a day to assess the patient,irect care, and perform any necessary invasive procedures isrucial. Post–cardiac surgical patients are fundamentally differ-nt from general ICU patients. Our institution believes that inrder to address the needs of all cardiac patients in an efficientanner, on-going optimization with in-house care is advanta-

eous. With our hybrid 24-hour model of care and direct ICU toard transfers, we were able to demonstrate a significant de-

rease in the total hospital length of stay by 1 median day—notnly advantageous for the patient, but also a cost savings for the
ealth care system.