Ann Thorac Surg 2002;73:1394-1401
© 2002 The Society of Thoracic Surgeons
Original article: cardiovascular
Safe, highly selective use of pulmonary artery catheters in coronary artery bypass grafting: an objective patient selection method
Thomas A. Schwann, MDa,b,
Anoar Zacharias, MDa,b,
Christopher J. Riordan, MDa,b,
Samuel J. Durham, MDa,b,
Milo Engoren, MDa,
Robert H. Habib, PhD*a,b
a Division of Cardiovascular Surgery, St. Vincent Mercy Medical Center, Toledo, Ohio, USA
b Medical College of Ohio, Toledo, Ohio, USA
Accepted for publication January 11, 2002.
* Address reprint requests to Dr Habib, Cardiopulmonary Research, St Vincent Mercy Medical Center, 2213 Cherry St, ACC Bldg, Suite 309, Toledo, OH 43608 USA
e-mail: robert_habib{at}mhsnr.org
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Abstract
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Background. Routine versus selective use of pulmonary artery catheter (PAC) monitoring in coronary artery bypass grafting operations is a topic of significant debate. Accordingly, we retrospectively examined operative outcomes in 2,685 consecutive (1994 to 1998) coronary artery bypass grafting patients in whom PAC use was highly selective. Next, we developed a quantitative model of PAC use in terms of its multivariate predictors as a means of providing an objective criterion for patient PAC use selection.
Methods. Safety of the implemented selective PAC use was assessed by comparisons to contemporaneous coronary artery bypass grafting outcome reported by The Society of Thoracic Surgeons’ national data. Continuous relations describing PAC use in terms of continuous univariate predictors were obtained using overlapping-range patient cohorts. Next, independent predictors of PAC use were derived by multivariate regression to best fit the categorical variable PAC (Yes = 1, No = 0). Model estimates were a continuous variable (PAC score) with values between 0 and 1.
Results. Planned use of PAC was based on collective consideration of preoperative patient variables, and was not limited to low-risk or preserved ejection fraction patients. Planned and unplanned use of PAC was limited to 176 (planned, 6.6%) and 66 (unplanned, 2.4%) patients, respectively, whereas no PAC was used in 2,443 (91%). Overall patient characteristics and risk factors in this series were comparable to contemporaneous Society of Thoracic Surgeons data, and the incidence of operative deaths was 2.31% (n = 61; observed-to-expected [Society of Thoracic Surgeons risk] mortality = 0.73). Independent predictors of PAC use were ejection fraction, Society of Thoracic Surgeons risk, intraaortic balloon pump, congestive heart failure, reoperative surgery, and New York Heart Association class IV. Expectedly, PAC scores were substantially different for PAC (mean ± standard deviation, 0.37 ± 0.20; median, 0.38) and no PAC (0.14 ± 0.11; median, 0.10) patients (p < 0.001). Area under the receiver operating characteristic curve derived for PAC score was relatively high (area, 0.85). Moreover, the corresponding summed sensitivity (0.68 to 0.91) and specificity (0.85 to 0.62) was maximized at 1.53 for PAC score between 0.15 and 0.31.
Conclusions. Our results indicate that highly selective use of PAC in coronary artery bypass grafting can be accomplished safely, and it need not be limited to patients with preserved ejection fractions or low operative risk. Indeed, coronary artery bypass grafting without PAC may be preferable in the vast majority of patients as it reduces catheter-associated risks and resource utilization without incurring an increased operative risk. Also, pending further prospective confirmation, our analysis suggests that collective consideration of PAC use predictors to derive a PAC score provides an objective criterion to minimize unnecessary use of PAC with an acceptably low probability of error.
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Introduction
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After its introduction in 1970 [1], use of pulmonary artery catheters (PAC) for invasive hemodynamic monitoring grew rapidly despite a lack of substantive direct evidence of its safety, efficacy, or improved patient outcomes [2–4]. Recent studies have raised questions regarding the appropriateness of routine use of PAC in critically ill and surgical patients [5, 6]. This is in addition to the possible implications of routine PAC use on cost of care [7, 8].
A large fraction of PAC utilization occurs in cardiac operations. In late 1998, we surveyed 48 large-volume cardiac surgery programs in the United States, and obtained 30 responses from institutions that performed between 725 and 3,000 cardiac operations in 1997 (data available upon request). The survey results showed that 20 of 30 (67%) programs used PACs routinely (
80%) in isolated coronary artery bypass grafting (CABG) compared with only 4 programs (13%) using it selectively (
20%).
Importantly, routine planned use of PAC occurs despite the fact that the large majority of CABG patients do not experience significant postoperative hemodynamic instability, are extubated expeditiously, and are transferred from intensive care within 24 hours of operation. In such patients, a PAC provides little or no clinical benefit, is arguably an unjustified resource utilization, and may represent additional unnecessary risk of catheter-related complications. Moreover, patients who develop late hemodynamic or cardiopulmonary complications will most likely have a new PAC inserted as the original catheters are typically removed during the first postoperative day unless clinical events dictate otherwise. We contend that optimal use of PAC in CABG should be limited to either patients with ongoing hemodynamic instability or those who are highly likely to develop such symptoms intraoperatively or early during the postoperative period. However, no objective method is currently available for identifying this subset of patients with a low probability of error.
For nearly two decades, we have adhered to a practice of highly selective PAC use in CABG that is not limited to low-risk patients or to those with preserved left ventricular function. Instead, planned use of PAC was based on a collective consideration of preoperative patient variables. In this study, we evaluate the safety of the above long-implemented approach by means of CABG outcome comparisons to contemporaneous Society of Thoracic Surgeons’ (STS) national data [9]. A second goal of this investigation was to develop objective criteria for PAC use patient selection. We thus derived a multivariate model that provides a preoperative PAC score that potentially represents a quantitative means for selecting patients in whom CABG can proceed without a PAC and in which the likelihood of unplanned postoperative PAC use is low. A prospective trial validating this model is underway.
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Material and methods
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Patients
With approval of the Saint Vincent Mercy Medical Center (Toledo, OH) Human Investigation Committee, we retrospectively studied 2,685 consecutive isolated CABG patients between January 1994 and end of June 1998 in whom PAC use was highly selective. Standard cardiopulmonary bypass techniques were applied in all patients with predominant (> 95%) use of normothermia [10]. Arterial blood flow during cardiopulmonary bypass was determined on the basis of a cardiac index of 2.5 to 3.0 L · min-1 · m-2, and mean arterial pressure was maintained at a minimum of 60 mm Hg. All surgeons used standardized clinical pathways for intraoperative and postoperative care to minimize intersurgeon variability. Demographics, risk factors, operative variables, postoperative complications, and operative mortality data were collected on each patient and entered into the cardiac surgery database according to STS definitions.
Utilization of pulmonary artery catheters
The decision to use a PAC during CABG, rather than standard central venous pressure (CVP) monitoring, was always made by the surgeon on the basis of a comprehensive consideration of preoperative variables. A single factor was rarely sufficient to cause use of PAC. Preoperative factors considered in selecting patients included whether the procedure was a reoperation, emergency, severity of left ventricular (LV) dysfunction (percent ejection fraction [EF]), left main coronary artery disease, unstable angina, recent myocardial infarction, renal failure, congestive heart failure, intraaortic balloon pump, and chronic obstructive pulmonary disease. Patients in whom intraoperative circumstances dictated placement of a PAC in the immediate postoperative period were considered as unplanned.
Pulmonary artery catheter subgroups
In this study, CABG patients who received a PAC during their admission were categorized to various study subgroups according to the flow chart in Figure 1.
Briefly, patients selected to receive a PAC were categorized as planned PAC patients (PACP), whereas those with unplanned use of PAC were categorized as PACU. All remaining patients were categorized as No PAC. Unplanned PAC patients were further divided to (1) PACU (Early), or those in whom a PAC was inserted either on arrival to the cardiovascular intensive care unit (CVICU) or during the first postoperative day 1; and (2) PACU (Late), or those with PAC insertions during or after postoperative day 2. Alternatively, to ascertain the efficacy of PAC use selection, PACP patients were further categorized to those who likely benefited from this monitoring [PACP (Benefit)] versus those who did not [PACP (No Benefit)]. Note the latter group consisted of all PACP patients who had an unremarkable postoperative course, ie, free of complications, hemodynamic instability or hospital death, expeditious extubation, and timely CVICU ( 1 day) and hospital ( 8 days) discharge. Accordingly, optimal PAC use should be limited to the PACP (Benefit) and PACU (Early) subgroups [PAC (Needed)].
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Fig 1. Block diagram depicting overall pulmonary artery catheter (PAC) use in 2,685 coronary artery bypass grafting patients subdivided into planned (PACP) and unplanned (PACU) categories (see Material and Methods for definitions).
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Data analysis
Overall safety of the selective PAC use in the study population was investigated by means of outcome comparisons to contemporaneous STS data. Univariate comparisons were performed with 
2 or Fischer’s exact test for categorical variables and either the unpaired Student’s t test or the nonparametric Mann-Whitney rank sum test for continuous variables, depending on applicability. A probability value less than 0.05 was always used to indicate significance (SigmaStat; Jandel Scientific, San Raphael, CA).
Multivariate regression was used in the 2,302 patients (212 had a PAC used) in whom EF data were available to derive a model of PAC use in CABG. Here, we first determined the patient variables that predicted use of PAC by appropriate univariate statistical methods. The role of continuous preoperative variables (age, preoperative hematocrit, EF, STS risk) in PAC use was investigated using overlapping-range cohorts as recently described by us [10]. This approach allowed the derivation of PAC use-continuous variable relations by nonlinear regression analysis. Second, we determined the independent predictors of PAC use by means of multiple linear regression analysis in which all univariate predictors were covaried to obtain a best fit of the categorical variable PAC (Yes = 1, No = 0). This multivariate model used a single coefficient for each variable, but coefficients of continuous predictors multiplied prederived PAC use-variable relation (eg, PAC versus EF) as opposed to the variable itself (or EF).
The multivariate model estimates represent a continuous variable that varies in terms of the independent predictors of PAC use. These estimates then effectively constitute a PAC score that varies between 0 and 1, and the greater the PAC score, the more is the likelihood of PAC use. Sensitivity, specificity, positive predictive value, negative predictive value, and area under the corresponding receiver operating characteristic curve were used to ascertain whether and how PAC score may be used to guide patient selection for PAC use.
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Results
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Preoperative, intraoperative, and postoperative patient data for the entire CABG population (n = 2,685) are summarized in Table 1,
and are contrasted to the 1997 national CABG data as published by the STS [9]. Briefly, this patient series was generally similar in age and comorbidities to the national cohort. Intraoperatively, the incidence of emergency operation, number of grafts per patients, and use of intraaortic balloon pump (intraoperatively and overall) were similar to national statistics whereas other variables differed. Duration of cardiopulmonary bypass and cross-clamp time were relatively less in our patients and may be a reflection of almost universal use of normothermic perfusion. Also, our use of internal mammary artery grafts was noticeably greater (91% versus 77%) and incidence of redo CABG was less (5.6% versus 7.9%). The largest variance from the national data were our lower use of inotropic support when leaving the operating room.
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Table 1. Comparison of Overall Preoperative, Intraoperative, and Postoperative Patient Data (n = 2,685) to the Contemporary National Cardiac Surgery Data as Published by The Society of Thoracic Surgeons
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Postoperatively, our outcome data were comparable to the national STS statistics (Table 1), excepting incidence of postoperative transfusion, which was less frequent in our series (27% versus 37%). Observed operative mortality was 2.31% (62 of 2,685), corresponding to an observed to expected mortality ratio of 0.73, both of which compare favorably to the contemporaneous STS data (2.76% and 0.89, respectively). Expected mortality used to compute observed to expected mortality ratios was derived from the STS CABG operative risk model [11].
Use of pulmonary artery catheter in coronary artery bypass grafting
A total of 242 patients received a PAC (9.0%) during their admission (Fig 1) compared with 2,443 patients (91%) who did not. Use of PAC was planned in 176 patients [PACP; 6.55%], whereas in 66 patients PAC use was unplanned [PACU; 2.46%]. In the latter group, PAC was inserted early after operation in 40 patients [PACU (Early); 1.5%] owing to unexpected intraoperative complications affecting ventricular function. Also, not infrequently, PAC was inserted early postoperatively as a result of hemorrhagic complications. Pulmonary artery catheter insertion was relatively late in 26 patients [PACU (Late); 1.0%], mostly as a consequence of single or multiorgan failure. Of the PACP group, 49 (1.8%) patients had an uncomplicated postoperative course with no hemodynamic instability [PACU (No Benefit)], whereas PAC was potentially useful in 127 (4.7%) patients whose clinical course was complicated or who experienced a slow postoperative recovery [PACU (Benefit)].
Predictors of pulmonary artery catheter use
Consideration of preoperative risk factors resulted in a total of 15 univariate (11 categorical, 4 continuous) predictors of PAC use. The incidence of each of these factors for PAC versus No PAC patients, the corresponding odds ratio (for categorical variables), and statistical significance are summarized in Table 2. The preoperative continuous PAC use predictors (hematocrit, age, EF, and STS risk) are shown in Figure 2.
Briefly, PAC use was systematically decreased as preoperative hematocrit (%) and EF (%) are increased. Conversely, PAC use was systematically greater with increasing age and operative risk. Note, the roles of age and EF in PAC use are partly reflected in the STS risk-PAC use relations. The independent predictors of PAC use by multivariate analysis were EF, STS risk, intraaortic balloon pump, congestive heart failure, redo operation, and New York Heart Association class IV (Table 3).
These variables, combined, determined a PAC score that is increased as the likelihood of PAC is increased.
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Fig 2. Frequency of overall pulmonary artery catheter (PAC), unplanned (PACU), early unplanned (PACU[Early]), and needed (PAC [Needed]) insertions shown in terms of overlapping-range subgroups [10] of all four univariate (continuous variable) predictors of PAC use: age (top, left), preoperative (Pre-Op) hematocrit (top, right), ejection fraction (bottom, left), and coronary artery bypass grafting risk according to The Society of Thoracic Surgeons (CABG STS risk; bottom, right). Dashed lines represent regression model fit (see equations below) to PAC versus predictor.    
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Pulmonary artery catheter score values were significantly greater for PAC (mean ± standard deviation, 0.37 ± 0.20; median, 0.38; n = 212) compared with No PAC patients (0.14 ± 0.11; median, 0.10; n = 2,090; p < 0.001). Within PAC patients, PAC scores were higher for PACP (0.40 ± 0.20; median, 0.4; n = 156) compared with PACU (0.29 ± 0.20; median, 0.19; n = 56) patients. The frequency and cumulative distribution of PAC scores from all 2,302 patients are shown in Figure 3.
Pulmonary artery catheter scores of No PAC patients (n = 2,090) followed a long-tailed unimodal distribution. Alternatively, these scores were expectedly greater in patients who received a PAC, and their distribution was bimodal with the most frequent scores (peaks) occurring at higher PAC scores compared with No PAC (Fig 3A, insert).
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Fig 3. (Top) Frequency distribution of pulmonary artery catheter (PAC) score values derived from the multivariate model (Table 3) shown as a percentage of all patients (Pts; n = 2,302; only those with known ejection fraction). Note that given the low use of PAC (9%), the long-tailed unimodal distribution of PAC score for All Pts is dominated by that for No PACpatients except at the highest values, at which the large majority of patients who received PAC scored. (Top, inset) PAC score values were expectedly greater for PAC patients and followed a bimodal distribution, particularly in cases of planned insertions (PACP). Circles are actual PACU (open) and PAC (closed) frequencies while lines are bimodal guassian fits to data. (Bottom) Corresponding cumulative frequency distributions of PAC score values. The area between the diverging all patients and No PAC curves reflects the cumulative distribution of PAC score in those who received PAC’s. (Bottom, inset) Cumulative distribution for PAC, unplanned (PACU), PAC (Needed), and PACU (Early) plotted versus PAC score. Note, PACP and PACU (Late) distributions may be inferred as PAC - PACU and PACU - PACU (Early), respectively. See Material and Methods and Figure 1 for definitions of various PAC use subgroups.
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Area under the receiver operating characteristic curve derived for PAC score to indicate CABG without PAC was relatively high at 0.851 (Fig 4).
Moreover, the corresponding summed sensitivity (range, 0.68 to 0.91) and specificity (range, 0.85 to 0.62) was similarly maximized at 1.53 for PAC score between 0.15 and 0.31 (Fig 4, insert). A PAC score of 0.17 represented the point of equal sensitivity and specificity (76%) and thus may represent the optimal objective criterion for PAC use patient selection.
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Fig 4. Receiver operating characteristic (R.O.C.) curve derived for pulmonary artery catheter (PAC) score as a criterion for coronary artery bypass grafting without PAC. (Inset) Corresponding sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) in terms of PAC score. Averaged sensitivity and specificity ([Sens. + Spec.] / 2) are plotted to show range of optimal PAC score values (0.15 to 0.31) to be used as an objective selection criterion.
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Comment
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Many cardiac surgery centers continue to use PACs in a large majority of CABG cases on the basis that placement of a PAC will allow (1) a more complete assessment of hemodynamics and (2) early and more targeted pharmacologic or surgical intervention to restore homeostasis [12–14]. However, a number of studies refute this and concurrently suggest that PAC use may represent additional unnecessary cost, particularly in low-risk patients with normal LV function [15–20]. Also, however rare, PAC may have serious associated risks such as pulmonary artery thrombosis or rupture, infection, arrhythmia(s), myocardial or valvular injury, insertion problems, and misinterpretation of PAC data by care providers [21–25]. Accordingly, whether and when to use PAC in CABG has become a topic of debate [5, 6, 26]. And, in its Year 2000 Research Survey to the national database participants, the STS queried the wisdom of routine as opposed to selective use of PAC in patients; particularly those who do not exhibit substantial LV dysfunction.
In this study, we present a series of 2,685 consecutive CABG patients in whom overall use of PAC was limited to 9% (6.6% planned), and in whom selective use was attempted irrespective of the degree of LV dysfunction (Fig 2). Surgical outcomes in this series were quite favorable (Table 1). Comparing these outcomes to the contemporaneous national data provided by the STS in which PAC use is more routine supports our contention that highly selective use of PAC in CABG is indeed safe. Additionally, selective PAC use on the basis of clinical judgment by the attending surgeon even in patient cohorts with significant LV dysfunction or high operative risk did not adversely affect outcomes (Fig 5).
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Fig 5. (Top) Observed (OMObs) and expected operative mortality (OMExp, equal to The Society of Thoracic Surgeons risk [STS Risk]) plotted in terms of ejection fraction (EF), in which the latter was determined for overlapping decile subgroups (n = 232 patients each) [10]. Observed operative mortality (squares) was systematically decreased as a function of increasing EF (thick solid line; p < 0.001). Note, the two lowest EF data points represent results from a smaller number of patients (50 and 160, respectively) with the lowest EF. Expected operative mortality (dashed line; p < 0.001) was also systematically less as EF increased (symbols for the raw data were intentionally excluded for graph clarity). (Inset) Corresponding observed-to-expected operative mortality ratios (O/E) based on actual raw data (squares) and regressions (solid line). (Bottom) Observed operative mortality plotted versus expected operative mortality as computed for overlapping decile patient subgroups with increasing STS Risk. Most points fall below O/E = 1 indicating favorable outcomes. Black square reflects results from 50 patients with the highest STS Risk (> 18%).
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At present, randomized trials of PAC use in CABG have not been reported, and we are unaware of any such studies in progress. In face of no data from randomized prospective trials, we must rely on retrospective analyses despite their shortcomings. A number of such studies support our findings. In 1983, Loop and colleagues [20] reported decreased hospital charges and both overall and CVICU hospital stays without increasing either morbidity or mortality when PAC use was limited to patients with EF less than 35% as one of several cost-saving measures. A 1989 study by Pearson and associates [19] prospectively randomly assigned 226 elective cardiac operation patients to either CVP, standard PAC, or oximetric PAC monitoring, but 46 of 74 patients randomly assigned to receive CVP had a PAC instead owing to anesthesiologist preference. The authors observed no significant differences in mortality and CVICU stays among the patient groups, although finding greater catheter and monitoring costs in PAC versus CVP patients. Bashein and colleagues [16] reported acceptably low mortality (0.72%) and perioperative myocardial infarction (3.2%) in 698 patients (55% of all cases) who underwent isolated CABG with CVP monitoring because their EF was at least 40% and they had no history of congestive heart failure and had a normal blood pressure response during exercise testing. Stewart and coworkers [18] used six criteria to preoperatively identify 194 of 312 (62%) low-risk CABG patients who would be candidates for CVP as opposed to PAC monitoring. Of these, CABG proceeded with CVP in 133 patients, whereas the remaining 61 patients had a PAC inserted owing to surgeon or anesthesiologist preference. In these two subgroups, in-hospital mortality was similar, although postoperative complications (morbidity) tended to be increased in PAC patients. These trends included significantly greater total volume infused in the first 12 hours, 24-hour weight gain, and time to extubation. Also, increases in both CVICU stay and total hospital charges trended toward statistical significance. In 1,094 patients assigned to receive either PAC or CVP catheters based on anesthesiologist preference, Tuman and associates [17] reported no significant between-group differences in morbidity or mortality and showed that 7% of CVP patients eventually required insertion of PAC after CABG. However, a subanalysis of these data showed that, when patients are divided into three increasing risk groups, those with a PAC inserted had longer CVICU stays and were more likely to have vasoactive drug infusions. Ramsey and colleagues [27] retrospectively reviewed all 1997 nonemergent CABG (13,907; 58% PAC used) operations from 56 community-based hospitals, and they found that PAC use in CABG was associated with a doubling of in-hospital mortality, increased hospital stay, and increased costs ($1,402 per patient) particularly for hospitals with low volume of PAC use.
Our data concur with others that CABG without PAC is more likely in patients with normal or near normal EF. However, the same data show that less than 40% of patients with severe LV dysfunction (EF 30%) actually require a PAC. Indeed, use of PAC was systematically lower as EF increased (Fig 2), and patients with normal LV function (EF 50%) had a PAC inserted very rarely (3.1%). Given the favorable surgical outcomes in this population irrespective of EF and operative risk (Fig 5), we believe that neither EF nor STS risk should be used alone to determine when a PAC is used.
A pertinent question in this patient series is whether patient selection for PAC use was too selective and hence resulting in too many unplanned insertions. Unplanned catheter insertions occurred in 66 of 2,865 patients (PACU, 2.5%) overall, and of these, 40 occurred early during the postoperative period (PACU [Early], 1.5%). This incidence is perhaps within acceptable limits of postoperative PAC insertions, and the relatively good surgical outcomes in this series suggest that the used PAC selection did not lead to adverse results. Nonetheless, roughly one in four PAC patients (66 of 242) were unplanned, and minimizing this rate of unplanned insertions by objective means may be of clinical benefit.
Selection of patients for planned use of PAC in this patient series was based on collective consideration, by the attending surgeon, of each patient’s preoperative data with the general aim of predicting those likely to develop hemodynamic instability. By retrospective analysis, a total of 15 patient variables were distinctly different between PAC and No PAC patients (Table 2), and of these, six risk factors (EF, STS risk, congestive heart failure, intraaortic balloon pump, reoperation, and New York Heart Association class IV) independently predicted PAC use by multivariate regression model analysis (Table 3). This model provided a PAC score in each patient, and the obtained distribution of PAC score values for the various patient subgroups potentially provides a basis for an objective patient selection criterion.
Inspecting the cumulative distribution of PAC scores (Fig 3, bottom) one notes (1) nearly 50% of all CABG patients had a PAC score less than or equal to 0.1 with essentially none of these patients receiving a PAC (planned or unplanned); and (2) 76.9% of patients had a PAC score less than or equal to 0.2 of whom only 2.3% received a PAC. Of these PAC patients, perioperative data indicated that additional monitoring was perhaps needed in 1.8% (Fig 3, bottom [insert]). These results suggest that PAC score as determined from the multivariate model described in Table 3 may be used to indicate CABG without PAC with a low probability of error. Indeed, this contention is supported by (1) the high area (0.851) under the corresponding receiver operating characteristic curve and (2) relatively high specificity and sensitivity of PAC score to PAC use for values ranging between 0.15 and 0.30 (Fig 4).
In summary, favorable outcomes obtained in a large CABG series in which PAC use was limited to 9% of all patients indicate that selective use of PAC in CABG is safe. Moreover, selective use is perhaps more efficacious in a large majority of CABG cases inasmuch as in these patients, the possibility of catheter-associated complications, unnecessary use of vasoactive drugs, and resource utilization are decreased. Another implication of our data are that preset limits for EF or operative risk for when to use PACs should be avoided, and that these variables should be two of several factors considered in selecting patients. Finally, when collectively considered in the form of a multivariate model (Table 3), predictors of PAC use provided an objective quantitative criterion (PAC score) that may be used to avoid unnecessary use of PAC in a large fraction of CABG patients with reasonably high sensitivity and specificity. Prospective confirmation of the safety and efficacy of limited PAC use based on a priori PAC score as suggested by our retrospective analysis is warranted.
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Invited commentary
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Ann. Thorac. Surg. 2002 73: 1401-1402.
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14(1):
40 - 45.
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Abstract
Introduction
