Fast-Track Cardiac Surgery in a Department of Veterans Affairs Patient Population

Fast-Track Cardiac Surgery in a Department of Veterans Affairs Patient Population Martin J. London, MD, A. Laurie W. Shroyer, PhD, Verna Jernigan, MS, David A. Fullerton, MD, Deborah Wilcox, BSN, Janet Baltz, RN, James M. Brown, MD, Samantha MaWhinney, ScD, Karl E. Hammermeister, MD, and Fredrick L. Grover, MD Departments of Anesthesiology, Cardiothoracic Surgery, Medicine, Nursing, Preventive Medicine and Biometrics, University of Colorado Health Sciences Center, Denver Veterans Affairs Medical Center, Denver, Colorado

Background. “Fast-track” (FT) cardiac surgery is popular in the private and university sectors. This study was designed to examine its safety and efficacy in the Department of Veterans Affairs elderly, male patient population, a population with multiple comorbid risk factors, often decreased social functioning, and impaired support systems. Methods. Time to extubation, hospital length of stay, perioperative morbidity, and mortality were studied in two consecutive cohorts undergoing cardiac operations requiring cardiopulmonary bypass before (pre-FT: n 5 255, January 1992 to September 1993) and after (FT: n 5 304, October 1993 to October 1995) institution of an FT protocol at a university-affiliated teaching Department of Veterans Affairs medical center. Preoperative risk factors, including a Department of Veterans Affairs risk-adjusted estimate of operative mortality, and perioperative surgical and anesthetic processes of care were evaluated. Results. The mean Department of Veterans Affairs risk estimate of perioperative mortality was not different between the pre-FT and FT cohorts (3.5% versus 3.7%, p 5 0.13). In the FT cohort, median time to extubation decreased significantly (19.2 versus 10.2 hours; p < 0.001)

along with median surgical intensive care unit stay (96 versus 49 hours; p < 0.001) and total postoperative length of stay (222 versus 167 hours; p < 0.001). Median postoperative day of hospital discharge decreased from day 10 to 7 (p < 0.001). One patient (0.3%) required emergent reintubation directly related to early extubation. Reintubation for medical reasons was unchanged between pre-FT and FT groups (6.3% versus 5.0%; p 5 0.48). Postoperative morbidity was similar between groups except for nosocomial pneumonia, the rate of which decreased significantly in the FT cohort (14.7% versus 7.3%; p < 0.005). Thirty-day (3.9% versus 4.6%; p 5 0.69) and 6-month mortality (6.7% versus 6.9%; p 5 0.91) were unchanged. Conclusions. An FT cardiac surgery protocol has been instituted in a university-affiliated teaching Department of Veterans Affairs medical center, with decreased length of stay and no significant increase in postoperative morbidity, 30-day mortality, or 6-month mortality. It was associated with a lower rate of nosocomial pneumonia, a finding that must be validated in a prospective study. (Ann Thorac Surg 1997;64:134 – 41) © 1997 by The Society of Thoracic Surgeons

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going cardiac operation. The median postoperative LOS was 4 days, and only 2.5% of patients were readmitted within 6 months of discharge. However, this approach was not widely adopted until reports from the Baystate Medical Center using a similar protocol, now termed “fast-track” (FT) management, documented similar findings [3]. It now appears that economic forces are leading to routine use of FT management across the United States and Canada, despite relatively limited data on its safety and efficacy among different patient populations undergoing cardiac operations. Approximately 7,000 cardiac surgical procedures are performed annually at 43 medical centers in the Department of Veterans Affairs (DVA) health care system [4]. These predominantly elderly, male patients have a high frequency of comorbid risk factors, particularly chronic obstructive pulmonary disease and current smoking, factors associated with postoperative pulmonary complications and considered by many to be contraindications to early postoperative extubation [5]. Other differences

ntil recently, the routine use of high doses of intraoperative and postoperative opioids and benzodiazepines resulted in mandatory overnight mechanical ventilation for all patients undergoing cardiac operations. Anecdotal reports and small clinical series in the late 1970s through the early 1980s documented the safety of early postoperative extubation, a practice facilitated by lower doses of intravenous anesthetic agents and greater use of volatile agents [1]. Despite these studies, there was little interest in, or incentive to, reduce hospital length of stay (LOS) at most centers. In 1990, Krohn and colleagues [2] presented data on a clinical pathway using patient and family education, early extubation, pharmacologic adjuvants (including perioperative steroids), aggressive mobilization, ambulation, and early hospital discharge in 240 patients under-

Accepted for publication Jan 20, 1997. Address reprint requests to Dr London, Anesthesia 112A, Veterans Affairs Medical Center, 1055 Clermont St, Denver, CO 80220 (e-mail: [email protected]).

© 1997 by The Society of Thoracic Surgeons Published by Elsevier Science Inc

0003-4975/97/$17.00 PII S0003-4975(97)00248-8

Ann Thorac Surg 1997;64:134 – 41

between this population and the private sector include lower socioeconomic status, lower functioning on quality of life scales, and impaired social support systems [6]. In the fall of 1993, an FT protocol similar to that of Engelman and associates [3] was implemented at the Denver Veterans Affairs Medical Center, a 276-acute care bed, university-affiliated teaching institution (see Appendix 1). In this report, observational data are presented on a retrospective cohort of cardiac surgery patients operated on before and after adoption of this protocol. The hypothesis of this investigation is that the FT protocol has resulted in a reduction in the duration of postoperative intubation and hospital LOS without significant change in morbidity or mortality.

Material and Methods Study Design After Institutional Review Board approval (9/15/95), retrospective data collection was instituted for this project. All patients undergoing cardiac operation at the Denver Veterans Affairs Medical Center requiring cardiopulmonary bypass (CPB) (with the exception of planned circulatory arrest) from January 14, 1992, to October 1, 1995, were entered into a database. Patients were stratified into two consecutive sequential cohorts: pre-FT (January 14, 1992 to September 30, 1993; n 5 255) and FT (October 1, 1993 to September 30, 1995; n 5 304). One patient in the FT cohort was studied twice (initial valve replacement with semielective replacement for endocarditis several months later). Preoperative risk factors were selected based on previous risk models developed by the DVA’s Continuous Improvement in Cardiac Surgery Program (CICSP) [4]. This CICSP model generates a “risk-adjusted” estimate of perioperative mortality. Perioperative processes of care specific to the FT protocol, as well as other processes known to independently influence patient outcome (such as surgical procedural details), were identified [7]. For the process of care and outcome variables chosen specifically for this study, a variety of sources were used, including the medical record, the DVA hospital computer system database, the national Beneficiary Indicator Records Locator System, the CICSP data set, and special software and reports developed by the hospital’s Information Resources Management Service.

Statistical Analyses Univariate statistical analyses were performed to determine differences between the pre-FT and FT patient groups. For continuous variables, unpaired t tests or the Wilcoxon rank sum test (the nonparametric analogue to the unpaired t test) was used. For discrete variables, a x2 test or Fisher’s exact test (for variables with small prevalence rates) was used. Deaths were censored in all postoperative time to event data elements, as appropriate. Kaplan-Meier survival analysis was used for selected variables measuring time to an event (eg, LOS). Statistical significance was accepted at a p value less than 0.05. Data were analyzed using the SAS, version 6.10 (SAS Institute, Cary, NC).

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Table 1. Patient Risk Factorsa Risk Factor Age Male sex Previous cardiac operation Surgical priorityb Elective Urgent Emergent Preop IABP Angina classc I and II III and IV NYHA class I and II III & IV Diseased coronary arteriesd 0 1 2 3 Left main $ 70% stenosis LV contraction scoree I (normal) II (mild) III (medium) IV (severe) V (very severe) Preoperative myocardial infarctionf Cardiomegaly (radiographic) Digoxin use (within 2 wk) Diuretic use (within 2 wk) IV nitroglycerin (within 48 h) Current smoking COPD FEV1 (L) Preoperative bronchodilator use Creatinine $ 2.0 mg/dL Diabetes Insulin dependent Oral hypoglycemic use Cerebrovascular diseaseg Peripheral vascular diseaseh Home . 50 miles from VAMC CICSP risk estimate (%)

Pre-FT

FT

p Value

62.4 6 9.4 99.6 9.0

63.4 6 9.6 99.3 11.2

0.15 1.00 0.40 0.44

86.7 8.2 5.1 4.3

85.5 6.9 7.6 5.9

20.4 79.6

14.8 85.2

87.1 12.9

91.1 8.9

8.2 12.6 32.6 46.7 12.2

6.3 12.8 38.2 42.8 7.9

63.5 18.8 11.0 5.9 0.8 56.9

56.9 18.1 14.1 10.2 0.7 56.9

0.99

16.9 9.0 17.7 18.0 29.8 23.5 2.9 6 0.7 8.2

25.7 15.1 26.3 19.4 29.6 35.5 2.6 6 0.8 14.1

0.01 0.03 0.01 0.68 1.00 0.002 0.001 0.03

2.8

2.6

0.93 0.06

9.8 10.2 17.7 11.8 60.4

11.2 16.8 17.8 19.7 63.5

0.40 0.08

0.12

0.50

3.5 6 3.8 3.7 6 3.6 median 2.3 median 2.5

0.09 0.26

0.97 0.01 0.45 0.13

a

All values are percent of total group unless otherwise specified. Surgical priority (elective 5 clinically stable, operation .72 hours after cardiac catheterization; urgent 5 clinical condition mandating prompt operation within 12 to 72 hours of catheterization; emergent 5 unstable clinical condition with operation on same day of catheterization). c d Angina class 5 Canadian Cardiovascular Society Class. Diseased e LV contraction score 5 ejection coronary arteries $50% stenosis. fraction based on preoperative contrast ventriculogram, radionuclide angiogram, or echocardiogram (I, $0.55; II, 0.54 to 0.45; III, 0.44 to 0.35; IV, f Preoperative myocardial infarction, myocar0.25 to 0.34; V, ,0.25). g Ceredial infarction by history or Q waves on electrocardiogram. brovascular disease, previous cerebrovascular accident/transient ischh Peripheral emic attacks or surgical repair or $50% carotid stenosis. vascular disease, disease of arteries to legs below aortic bifurcation manifested by claudication or surgical repair or absent or diminished pulses or $50% stenosis. b

COPD 5 chronic obstructive pulmonary disease (history of functional disability or hospitalization, or chronic bronchodilator use or FEV1 ,75% FT 5 predicted); FEV1 5 forced expiratory volume in 1 second; fast-track; IABP 5 intraaortic balloon pump; NYHA 5 New York Heart Association.

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Results Patient risk factors are presented in Table 1. The CICSP risk estimate of operative mortality was not statistically different between the pre-FT and FT cohorts (3.5% versus 3.7%; p 5 0.13). There were, however, statistically significant differences in several factors used to calculate this estimate (peripheral vascular disease, cardiomegaly, preoperative digoxin use, and preoperative diuretic use). Three variables independently evaluating preexisting lung disease— clinical diagnosis of chronic obstructive pulmonary disease, preoperative forced expiratory volume in 1 second, and the preoperative use of a bronchodilator—show statistical changes suggestive of a greater degree of underlying lung disease in the FT cohort. Intraoperative and selected early postoperative procedural details are presented in Table 2. Internal mammary artery grafts were commonly used (usually single left, although bilateral or gastroepiploic grafts were used in several patients in the FT cohort). Moderate or mild systemic hypothermia (systemic temperature ,30°C or $30°C, respectively) was used in nearly all patients. However, mild hypothermia was used in a greater percentage of the FT cohort (24% versus 8%, FT versus pre-FT; p , 0.001). Although our clinical practice generally uses both antegrade and retrograde cardioplegia administration, only data on the use of retrograde cardioplegia are presented, as it was not possible to determine exactly which patients had antegrade cardioplegia from the archival sources. The frequency of failed retrograde administration, usually from dislodgement of the catheter, was similar in both groups. Duration of time in the operating room, ischemic arrest time, and total CPB time have decreased modestly. The frequency of intraoperative complications related to surgical technique (either iatrogenic or attributable to underlying disease) was similar between cohorts. The increase in pre-CPB use of nitroglycerin usually during the period of aortic cannulation is most likely related to the use of “lighter” anesthesia. There was no change in the frequency of use of intraaortic balloon pumping for weaning. A significantly greater serum glucose value obtained on arrival to the surgical intensive care unit (SICU) was noted in the FT group in diabetic and nondiabetic patients. Postoperative oral anticoagulation with warfarin, either for preexisting conditions or a new indication (eg, refractory atrial fibrillation or markedly impaired ventricular function), was not different between cohorts. Also shown in Table 2 are several non-FT protocol, deliberate changes in our processes of care instituted in temporal association with the FT protocol. Most notable are our successful efforts to reduce intraoperative blood product use. Use of intraoperative transesophageal echocardiography continues to increase since acquisition of a dedicated operating room unit in March 1992. Fast-track “specific” processes of care are presented in Table 3. Intraoperative crystalloid administration (nonCPB) has decreased significantly, along with a more modest reduction in colloid use. The frequency of volatile

Ann Thorac Surg 1997;64:134 – 41

Table 2. Intraoperative and Postoperative Procedural Detailsa Procedural Detail

Pre-FT

FT

Type of operation CABG only 85.1 86.8 Valve only 9.0 7.6 Valve/CABG 5.1 5.6 Other cardiac 0.8 0.0 Distal vessels grafted (no.) 3.3 6 1.0 3.2 6 1.0 Arterial graftsb 74.8 76.5 Total operating room time (h) Without prep time 6.1 6 1.5 5.2 6 1.2 With prep time 7.0 6 1.6 6.1 6 1.3 CPB time (min) 137 6 42 126 6 41 Ischemic time (min) 85 6 29 79 6 26 Pre-CPB use Nitroglycerin 37.7 51.2 Inotropes 5.1 7.0 Retrograde cardioplegia 90.2 94.8 Lowest temperature on CPB 27.4 6 2.3 28.2 6 2.8 (°C) Low temperature ,30°C on 91.9 75.8 CPB TEE use 35.3 49.5 IABP for weaningc 3.9 4.6 Intraoperative complications Revision of vein/arterial 2.4 1.4 graft LIMA taken down, not 4.0 3.1 used Any tear or laceration 2.8 3.5 Failed retrograde 4.8 4.5 cardioplegia Intraoperative death 0.8 0.3 Intraoperative blood products Fresh frozen plasma 19.2 9.9 Homologous RBC 49.6 31.9 Platelets 23.1 12.5 No transfusion 45.9 65.1 Total urine output (mL) 2083 6 932 1706 6 790 Data on SICU arrival Temperature (°C) 36.6 6 0.8 36.7 6 0.7 Serum glucose (mg/dL) 172 6 58 235 6 70 Platelet count (31,000/mL) 149 6 48 144 6 46 Postop warfarin use 14.2 15.2

p Value 0.49

0.38 0.65 ,0.001 ,0.001 ,0.001 0.01 ,0.001 0.36 0.04 ,0.001 ,0.001 ,0.001 0.69 0.52 0.56 0.67 0.85 0.59 0.002 ,0.001 ,0.001 ,0.001 ,0.001 0.21 ,0.001 0.31 0.75

a

All values are percentage of total group unless otherwise specified. Arterial grafts (left or right unilateral or bilateral internal mammary or gastroepiploic) as a percentage of eligible cases (ie, coronary artery c Exclusive bypass grafting or valve/coronary artery bypass grafting). of patients with preoperation intraaortic balloon pump. b

CABG 5 coronary artery bypass grafting; CPB 5 cardiopulmonary bypass; FT 5 fast track; LIMA 5 left internal mammary artery; RBC 5 packed red blood cells; SICU 5 surgical intensive care unit; TEE 5 transesophageal echocardiography.

anesthesia use, defined as 15 minutes or more of use (not including CPB), has increased to include 96% of patients in the FT cohort. Although opioids continue to be used in all patients, the doses have been reduced significantly. Use of midazolam has also decreased significantly, in

Ann Thorac Surg 1997;64:134 – 41

LONDON ET AL FAST-TRACK IN A VETERANS POPULATION

Table 3. Fast-Track Procedural Detailsa Procedural Detail Intraoperative fluid use Crystalloid (mL) Colloid (mL) Pre/Post-CPB anesthesia details Volatile agent used Fentanyl used Fentanyl dose (mg/kg) Sufentanil used Sufentanil dose (mg/kg) Midazolam used Midazolam dose (mg/kg) CPB anesthesia Isoflurane used Maximum inspired concentration (%) Percent total CPB time isoflurane used Temperature isoflurane discontinued (°C) Perioperative monitoring Mixed venous PA catheter a

Pre-FT

FT

p Value

3334 6 1182 2632 6 934 782 6 585 678 6 562

,0.001 0.01

59.6 70.2 93.4 6 32.1 29.8 10.3 6 5.7 97.7 0.16 6 0.08

95.7 56.3 41.6 6 19.3 44.7 3.7 6 1.8 81.6 0.08 6 0.05

,0.001 ,0.001 ,0.001 ,0.001 ,0.001 ,0.001 ,0.001

39.7 1.2 6 0.6

77.6 1.3 6 0.8

,0.001 0.52

19.9 6 14.4

45.9 6 25.0

,0.001

29.5 6 2.3

33.4 6 3.1

,0.001

71.7

41.4

,0.001

All values are percentage of total group unless otherwise specified.

CPB 5 cardiopulmonary bypass; artery.

FT 5 fast-track;

PA 5 pulmonary

part related to one attending physician’s practice of substituting its use by the shorter-acting hypnotic agent propofol by continuous infusion. The dose of midazolam has decreased by 50%. Isoflurane use during CPB has increased significantly, as has the duration of administration (including its use during the rewarming period of CPB). The maximum inspired concentration has not changed significantly. Finally, our deliberate efforts to decrease use of the more expensive mixed venous pulmonary artery catheter are apparent. Patient outcomes are presented in Table 4. The duration of postoperative intubation has been significantly reduced, with approximately 50% of patients extubated by 10 hours in comparison with 19 hours in the pre-FT cohort. The distribution of times to extubation in the FT cohort is bimodal with a “fast” group (ie, extubation the same day; median, 5.5 hours) and a “slow” group (extubation the next day or later; median, 18.8 hours). Only 1 FT patient required emergent reintubation on the day of operation. The frequency of reintubation due to medical reasons, primarily for progressive respiratory failure because of deteriorating cardiac status, sepsis, or pulmonary disease, was not different between groups (excluded are patients intubated for additional postoperative surgical procedures). Length of stay has decreased significantly in all of the phases of the hospital stay. The lengthy preoperative LOS is attributable to a predominance of patients who undergo cardiac catheterization on the same admission (most of whom are admitted with unstable angina). Although not directly attributable to the FT protocol, a

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significant reduction was noted (median, 159 versus 113 hours; p , 0.001) The greatest reduction has occurred in SICU LOS from a median of 96 to 49 hours (p , 0.001). The principal reason for this is more rapid transfer to our intermediate care unit (a move that necessitates removal of all invasive monitoring lines, mediastinal drains, and Table 4. Patient Outcomesa Outcome Duration of intubation (h) Mean Median Reintubation for medical reasons Preop LOS (h) Mean Median Postop SICU LOS (h) Mean Median Postop SICU 1 intermediate care unit LOS (h) Mean Median Postop total LOS (h) Mean Median Median postop day discharge 30-day mortality 6-month mortality No postop complications Postop complications (major) Adult respiratory distress syndrome Cardiac arrest/ventricular fibrillation Cerebrovascular accident New dialysis Reoperation for bleeding Return to CPB (intraop)b Postoperative IABP Operation for sternal infection Postop complications (minor) Atrial fibrillation requiring therapy Any arrhythmia requiring therapy Prolonged use supplemental oxygen Pneumonia requiring antibiotics Discharge home on nasal oxygen Other postop operationc Major Minor None

Pre-FT

FT

p Value

27.8 6 28.3 17.3 6 28.6 ,0.001 19.2 10.2 6.3 5.0 0.48 202 6 189 159

141 6 136 113

,0.001

144 6 204 96

91 6 145 49

,0.001

196 6 225 142

143 6 231 92

,0.001

291 6 213 222 10 3.9 6.7 35.1

228 6 252 167 7 4.6 6.9 38.4

,0.001 ,0.001 0.69 0.91 0.42

2.8

2.0

0.54

1.6

2.6

0.39

1.6 2.4 2.0 9.8 0.4 2.0

2.0 0.7 1.0 9.2 0.3 2.0

1.00 0.15 0.48 0.81 1.00 1.00

12.8

18.2

0.08

21.9

25.8

0.28

20.3

22.2

0.59

14.7

7.3

0.005

6.0

9.9

0.09

2.8 3.9 93.3

2.3 4.6 93.1

0.88

a

All values are percentage of total group unless otherwise specified. Any return to cardiopulmonary bypass noted on perfusion record after c Major operation defined as open body initial weaning attempt. cavity, minor operation included tracheostomy, tube gastrostomy, leg wound debridement. b

CPB 5 cardiopulmonary bypass; FT 5 fast-track; IABP 5 intraaortic balloon pump; LOS 5 length of stay; SICU 5 surgical intensive care unit.

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Table 5. Stratification of Pre–Fast-Track and Fast-Track Cohorts by Continuous Improvement in Cardiac Surgery Program Risk Estimate CICSP Risk Estimate (%) 0.0 to 2.5 .2.5 to 5.0 .5.0 to 7.5 .7.5 a

Percent in Each Risk Group Pre-FT

FT

56.5 23.5 11.0 9.0

p , 0.001 Pre-FT versus FT.

51.4 27.6 9.5 11.5 b

Median Duration of Intubation (h) Pre-FT

FT

Pre-FT a

18.3 20.4 18.3 39.9

Median SICU LOS (h)

7.3 14.2a 17.6 19.4b

90.3 117.8 116.3 113.1

FT a

47.5 53.1a 48.8a 70.1b

Median Postop LOS (days) Pre-FT

FT

9.0 12.0 14.0 13.5

6.5a 8.5a 8.0b 10.0b

p , 0.05 Pre-FT versus FT.

CICSP 5 Continuous Improvement in Cardiac Surgery Program;

FT 5 fast-track;

absence of intravenous inotropic support). The frequency of readmission to the SICU or intermediate care unit from the surgical ward for postoperative complications was unchanged. The reduction in total postoperative LOS is significant, although less dramatic than time in monitored acute care settings. The overall impact of these changes is reduction in our median postoperative day of discharge from day 10 to 7 (p , 0.001). Neither the incidence of major nor minor complications (Table 4) has changed significantly, with the exception of a significant reduction in the incidence of nosocomial pneumonia (50% decrease). Within the FT cohort the frequency of pneumonia was highest in patients remaining intubated 10 hours or more (9.2% versus 3.9%; p 5 0.09). There was a trend toward a higher incidence of atrial fibrillation in the FT cohort, although it did not reach statistical significance (12.8 versus 18.2%; p 5 0.08). There were no documented episodes of recall of intraoperative events in either group. Thirty-day (3.9% versus 4.6%; p 5 0.69) and 6-month mortality (6.7% versus 6.9%; p 5 0.91) were not significantly different. Comparison of changes in duration of intubation and LOS variables stratified by CICSP risk estimate groups revealed significant changes, or a trend toward significance, within all strata between the pre-FT and FT cohorts (Table 5). No significant changes were noted in either 30-day or 6-month mortality across these same groups (data not shown).

Comment This study reports on FT cardiac surgical management in a Department of Veterans Affairs population. The FT protocol is associated with a reduction in time to extubation along with SICU, intermediate care, and ward LOS. We have documented that patients may be managed with a FT protocol safely, as no major changes in postoperative mortality or morbidity were observed. In addition, our data suggest that this practice may be associated with a reduction in the frequency of nosocomial pneumonia. These results must be considered in the context of our study limitations, which include retrospective data collection, limitation to a single medical center, small sample size, potential confounding changes in important

LOS 5 length of stay;

SICU 5 surgical intensive care unit.

processes of care (including, but not limited to, concurrent attempts to curtail perioperative blood product use and inherent trends over time in care patterns toward reduced resource use and cost containment), and sequential cohort analysis. Despite retrospective data extraction, we are relatively confident of the accuracy of our major study outcomes given use of the DVA’s sophisticated computerized clinical information system (Decentralized Hospital Computer Program) from which many types of administrative, clinical, and laboratory data are accessible (including discharge summaries, operative dictations, and LOS data) [8]. Use of several redundant data sources, both archival at our medical center and in the DVA hospital computer system database, allowed us to triangulate in on incomplete data and verify any conflicting data. Our analysis failed to demonstrate any significant difference in the CICSP risk estimate of operative mortality between cohorts, although several factors used to calculate the risk estimate changed, along with several independent factors (see Table 1). The clinical significance of these differences is questionable given our small sample size and retrospective data collection. However, our observation that the frequency of three independent variables related to underlying pulmonary disease— clinical diagnosis of chronic obstructive pulmonary disease, actual forced expiratory volume in 1 second, and preoperative use of bronchodilators—were higher in the FT cohort would seem to negate any substantial bias against operating on “sicker” patients, particularly those with comorbid factors that might affect success of early extubation. Analysis of study outcomes by CICSP risk strata, with significant changes noted in nearly all strata between the pre-FT and FT cohorts (with no corresponding change in mortality), support our belief that “global changes” in our processes of care were successful. Several different anesthetic agents and techniques are used by different anesthesiologist/resident physicians. It is tempting to speculate that a certain combination of agents or doses is more effective in facilitating early extubation than another. However, aside from the general conclusion noted by others, that “inhalation-based” techniques or “low-dose” opioid techniques are required, these issues cannot be determined from this study because of the small sample size and study design

Ann Thorac Surg 1997;64:134 – 41

limitations [1]. Lack of a randomized, standardized anesthetic protocol, along with variable criteria for extubation based on different pulmonary consultants in the SICU, preclude any firm conclusions. Our current FT practice is geared toward earlier wake up and extubation, often within 2 to 3 hours after operation. Pharmacologic differences may be more important with this more aggressive strategy. Absence of intraoperative recall in either group suggests that our current anesthetic management is adequate to prevent this feared, although rare, complication [9]. An important issue is the safety of early extubation, with the potential for emergent reintubation in patients managed on an FT protocol. In our institution, this was a particular concern given absence of in-house anesthesia personnel after hours. As well, the practice of limiting extubation to the “daylight” hours was deeply ingrained. Although we considered these issues carefully, we elected to proceed with this protocol. We believe that the finding that only 1 FT patient, extubated on the day of operation, required emergent reintubation supports our practice. We now routinely extubate most patients during the late evening hours. We noted a statistically significant reduction in the frequency of postoperative nosocomial pneumonia in the FT group as reported on the discharge summary. However, precisely defining nosocomial pneumonia, even in a prospective study, is difficult and controversial [10]. Given a strong presence by our Infection Control Team (with dedicated nurse specialists) incorporating mandatory sputum culture surveillance and Centers for Disease Control definitions for nosocomial pneumonia, it is likely that these data are accurate [11]. We hypothesize that early extubation is associated with less impairment of pulmonary defense mechanisms (eg, better ability to cough and raise secretions), as clinical studies have shown adverse effects on these parameters during mechanical ventilation [12]. However, this observation requires prospective evaluation because other changes in our processes of care (ie, respiratory therapy ventilator management, suctioning protocols, and equipment changes unrelated to our FT protocol) could be solely responsible. An interesting observation was the increase in serum glucose levels noted on arrival in the SICU in the FT cohort. Although mild postoperative hyperglycemia is expected, as noted in the pre-FT cohort, the greater increase in the FT group is striking. We believe it is related to the use of intraoperative methylprednisolone, although increased catecholamine release related to lighter anesthesia or CPB effects cannot be discounted [13]. The mean levels observed are not life threatening, although potential adverse effects of hyperglycemia in the setting of cerebral ischemia, effects on electrolyte balance and urine output, and other factors make this issue worthy of further study [14]. As noted in Table 2, the measures to reduce excessive blood product use instituted in close temporal association with the FT protocol were successful. This strategy could have had independent favorable effects on periop-

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erative morbidity, including lower infection rates and improved pulmonary function due to avoidance of the potential adverse immunomodulatory effects of homologous transfusion [15]. As well, the use of mild hypothermia (usually 32°C) increased modestly in the FT cohort. However, the role of temperature as a predictor of success of early extubation has not yet been specifically addressed in our analyses. Given that the vast majority of our patients are normothermic (or nearly so) on arrival in the SICU (Table 2), the lowest temperature on CPB may not be as important. The similar success of an FT protocol implemented at two centers reported by Engelman and colleagues [3], one using normothermic CPB and the other using hypothermic CPB (although the exact degree is not reported), supports this contention. An important consideration in evaluating the efficacy of this protocol is the potential for early readmission due to medical or surgical complications, and even death, after discharge. Given the high percentage of veterans from outside our metropolitan area, many of whom do not return to our center for postoperative follow-up, we were unable to verify all hospital readmissions. However, any patients requiring surgical sternal debridement do return to our institution. We did not observe any difference in this complication between cohorts. We also noted no differences between cohorts in 30-day and 6-month mortality. However, our observation of 1 patient in the FT cohort with sudden ventricular fibrillation arrest on postoperative day 7 just before planned hospital discharge (resulting in implantable defibrillator placement) raises concerns that the absolute safety of rapid hospital discharge has not been defined precisely. Our data suggest, but do not prove, that comorbidities and social factors may have hampered efforts to decrease LOS. We have observed that the greater reduction in monitored LOS relative to overall postoperative LOS is at times related to either slowly resolving “minor” physiologic problems (ie, prolonged nasal oxygen requirements attributable to atelectasis) or problems in discharge planning and transportation. Given that more than half of our patients live more than 50 miles from our center (many in isolated rural areas), this may complicate discharge planning. Other factors seen in the DVA system include a high percentage of care delivered by resident physicians and constrained financial resources [16]. We believe that our demonstration that an FT protocol can be successfully implemented in the DVA suggests that these factors are not insurmountable in effecting changes to increase efficiency, while maintaining the quality of patient care delivered. We acknowledge the dedication and hard work of Sharon Del Hotal, secretary, Anesthesia Section, without whom this study would not have been performed. We also acknowledge the contributions of Elizabeth Munoz with data entry, Donald Huckaby, computer programmer, and Micheal B. Jones, Chief, Information Resources Management Service, for length of stay data extraction; John Hawk, PharmD, for operating room pharmacy records; Judith Wilson, RN, for support from the Nursing Service; Douglas Blankenship, RN, for infection control data;

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Joseph R. Coll, MS, for statistical analysis; Lyle E. Kirson, DDS, and the other cardiac anesthesia attending staff for support of FT management; Stephen Jones, MD, former cardiothoracic surgical fellow, for his clinical efforts; Cynthia Ackerman and the Baxter Perfusionists for perfusion data; and Charles P. Gibbs, MD, Chairman, Department of Anesthesiology, University of Colorado Health Sciences Center, for his gracious support for this project. This study was funded in part by Cooperative Study in Health Services No. 5 (“Processes, Structures and Outcomes of Care in Cardiac Surgery”) from the Department of Veterans Affairs Health Services Research and Development Service.

References 1. Shapiro BA, Lichtenthal PR. Inhalation-based anesthetic techniques are the key to early extubation of the cardiac surgical patient. J Cardiothorac Vasc Anesth 1993;7:135– 6. 2. Krohn BG, Kay JH, Mendez MA, et al. Rapid sustained recovery after cardiac operations. J Thorac Cardiovasc Surg 1990;100:194–7. 3. Engelman RM, Rousou JA, Flack JE, et al. Fast-track recovery of the coronary bypass patient. Ann Thorac Surg 1994;58: 1742– 6. 4. Grover FL, Johnson RR, Shroyer AL, et al. The Veterans Affairs Continuous Improvement in Cardiac Surgery Study. Ann Thorac Surg 1994;58:1845–51. 5. Warner MA, Offord KP, Warner ME, et al. Role of preoperative cessation of smoking and other factors in postoperative pulmonary complications: a blinded prospective study of coronary artery bypass patients. Mayo Clinic Proc 1989;64: 609–16. 6. McCarthy MJ, Jr., Shroyer AL, Sethi GK, et al. Self-report measures for assessing treatment outcomes in cardiac surgery patients. Med Care 1995;33:OS76 – 85. 7. Shroyer AL, London MJ, Sethi GK, et al. Relationships between patient-related risk factors, processes, structures, and outcomes of cardiac surgical care. Conceptual models. Med Care 1995;33:OS26 –34. 8. Ginsburg RE. 1994 Edward R. Stitt Lecture Award. Organizational analysis of the Veterans Administration decentralized hospital computer system: the challenge of innovation in a bureaucratic setting. Milit Med 1995;160:161–7. 9. Gild WM. Risk management in cardiac anesthesia: the ASA Closed Claims Project perspective. J Cardiothorac Vasc Anesth 1994;8(Suppl 1):3– 6. 10. Bonten MJ, Gaillard CA, Wouters EF, et al. Problems in diagnosing nosocomial pneumonia in mechanically ventilated patients: a review. Crit Care Med 1994;22:1683–91. 11. Garner JS, Jarvis WR, Emori TG, et al. CDC definitions for nosocomial infections, 1988. Am J Infect Control 1988;16: 128– 40. 12. Konrad F, Schreiber T, Brecht-Kraus D, et al. Mucociliary transport in ICU patients. Chest 1994;105:237– 41. 13. Lehot JJ, Piriz H, Villard J, et al. Glucose homeostasis. Comparison between hypothermic and normothermic cardiopulmonary bypass. Chest 1992;102:106–11. 14. Sieber FE, Traystman RJ. Special issues: glucose and the brain. Crit Care Med 1992;20:104–14. 15. Landers DF, Hill GE, Wong KC, et al. Blood transfusioninduced immunomodulation. Anesth Analg 1996;82:187–204. 16. Fisher ES, Welch HG. The future of the Department of Veterans Affairs health care system. JAMA 1995;273:651–5.

Appendix 1.

Protocols

Fast-Track Protocol Patients admitted to the Denver Veterans Affairs Medical Center for cardiac operation are managed by a team of surgical residents led by a cardiothoracic surgery resident supervised by a cardiothoracic surgical attending physician. A full-time cardio-

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thoracic nurse coordinator assists in admission and discharge planning, patient and family education, and communication. Anesthesia care is provided by cardiothoracic anesthesia residents and attending physicians. The FT protocol was developed by the Chief of Surgery, the Chief of Anesthesiology, the Chief of Cardiothoracic Surgery, the Cardiothoracic Nurse Coordinator, and the Head Nurse of the Surgical Intensive Care Unit. Administration of preoperative cardiac medications is continued up until the time of operation and patients are premedicated with intramuscular morphine supplemented by lorazepam or scopolamine. All patients are monitored with indwelling radial artery catheters. Pulmonary artery catheterization through the right internal jugular vein is performed before or after induction of anesthesia at the discretion of the anesthesia attending physician. Anesthesia technique before institution of the FT protocol used high-dose opioids (fentanyl or sufentanil) supplemented by midazolam, with limited use of volatile anesthetics. After institution of the FT protocol, doses of intravenous opioids and benzodiazepines were reduced and use of volatile anesthetic agents or short-acting intravenous agents was increased. Routine use of isoflurane during cardiopulmonary bypass, by way of a vaporizer on the CPB machine, was encouraged. In contrast to previous practice, it is continued during the rewarming period, up to 5 to 10 minutes before weaning. Long-acting muscle relaxants, commonly used before, were discouraged in favor of intermediate-duration agents (ie, vecuronium, rocuronium). Cardiopulmonary bypass is performed using nonpulsatile bypass with a centrifugal pump and a membrane oxygenator. Myocardial preservation is accomplished using varying combinations of retrograde and antegrade cold crystalloid and blood cardioplegia after institution of either mild or moderate hypothermia. Adjuvant intraoperative pharmacologic agents administered intravenously include methylprednisolone sodium succinate (500 mg), metoclopramide (10 mg), digoxin (0.5 mg), «-aminocaproic acid (5 g), and vitamin K (10 mg). The dose of methylprednisolone was increased in June 1994 from 100 to 500 mg (except in insulin-dependent diabetics, who receive 250 mg). Postoperative methylprednisolone administration (125 mg intravenously every 8 hours for three doses) was sporadic until April 1994, but is now routine, along with intravenous metoclopramide (10 mg every 8 hours for three doses) and digoxin (0.25 mg intravenously or by mouth once a day, continued for 4 weeks postoperatively). Efforts to decrease total time in the operating room, including surgical and CPB times, were emphasized to all clinical staff. Efforts to minimize total fluid administration and blood product administration where appropriate, as well as increasing use of less expensive nonprotein colloids (eg, hetastarch), were also emphasized. To reduce LOS, early transfer from the SICU to the intermediate care unit (“stepdown unit”) on the day after operation (postoperative day 1) was instituted in patients who had been successfully extubated the day of operation (postoperative day 0) and in whom mediastinal drains and the pulmonary artery catheter were removed. Rapid mobilization and ambulation were emphasized with transfer to the surgical ward on postoperative day 2 and hospital discharge by postoperative day 5 in patients with stable hemodynamics, adequate mental status, ability to ambulate and eat, afebrile status, and adequate family or social support systems. Same-day admission was not used in this cohort. To reduce costs, criteria for the use of the more expensive mixed venous oxygen saturation pulmonary artery catheter were agreed on by the anesthesia and surgical staff, substantially reducing its previous routine use. Use of intraoperative transesophageal echocardiography is at the discretion of

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the anesthesiology attending physician, unless requested by the surgeon. Postoperatively, selective ordering of laboratory tests, chest radiographs, and electrocardiograms based on patient condition alone was encouraged. Several months after institution of the protocol, a formal, written clinical pathway was finalized and adopted. This pathway addresses patient assessment, consultations, diagnostic testing, specific therapeutic treatments, medications, nutrition, patient activity, patient education, and discharge planning throughout each phase of the perioperative period.

Ventilator Management and Weaning Protocol In the initial phases of the protocol’s institution early postoperative extubation of low-risk patients was emphasized. Upon arrival in the SICU, the anesthesia attending physician relayed that the patient was a suitable candidate based on a favorable preoperative risk profile, use of a “low-dose” anesthetic regimen, and an uncomplicated intraoperative course. Management of postoperative mechanical ventilation and the actual timing of extubation is directed by pulmonary/critical care medicine consultation with a fellow/attending physician team with input from the anesthesia and surgical staff. Over time, a protocol emphasizing synchronized intermittent mandatory ventilation was instituted in favor of assist control ventilation. Initial tidal volumes range from 10 to 15 mL/kg depending on clinical factors (eg, stretch on internal mammary artery graft, degree of preoperative obstructive lung disease). Initial inspired oxygen settings (70% to 80% in uncomplicated cases) are recommended by the anesthesiologist, based on arterial blood gas results and pulse oximetry before CPB on arrival in the SICU.

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Based on the patient’s time to awakening, body temperature greater than 36°C, hemodynamic stability on minimal inotropic support, chest radiograph results, and lack of excessive mediastinal bleeding, the patient is rapidly advanced to lower ventilator rates and inspired oxygen concentration using pulse oximetry and selective arterial blood gas analysis. Neuromuscular blocker reversal agents (edrophonium or neostigmine) are routinely administered after the patient has a stable temperature of more than 36°C. The patient is advanced to a T-piece or to continuous positive airway pressure spontaneous ventilation. After a period of 20 to 30 minutes of spontaneous ventilation, an arterial blood gas measurement is obtained and if adequate (ie, based on the specific patient’s preoperative pulmonary function tests and room air oxygen saturation), the patient is extubated. Supplemental oxygen (40% to 60%) is administered initially through a humidified face tent and nasal prongs. The patient is weaned to room air during the following 24 hours based on pulse oximetry measurements. After the first several months, higher risk patients were considered for early extubation, including those undergoing redo procedures, patients with impaired preoperative pulmonary function results, those with impaired ejection fraction, and those requiring moderate inotropic support. Patients leaving the operating room with an intraaortic balloon pump or those receiving high doses of inotropic agents were not considered candidates, although all are treated with FT pharmacologic adjuvants and are initially managed with a “light” anesthetic. Unstable patients after CPB are given additional doses of opioids as tolerated and muscle relaxants before leaving the operating room.