Predicting mortality.
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Acute Kidney Injury↗
Biomedical subjects
Milo Engoren
Publications and source records attributed to Milo Engoren.
Is hospital procedure volume a reliable marker of quality for coronary artery bypass surgery? A comparison of risk and propensity adjusted operative and midterm outcomes.
BACKGROUND: Worse operative mortality has been reported for hospitals with low versus high coronary artery bypass grafting surgery volumes. Despite a lack of comparisons beyond the early postoperative period and evidence of surgeon-volume confounding, some have suggested that regionalization of coronary artery bypass grafting in favor of high volume institutions is warranted. METHODS: We retrospectively compared operative mortality and 3-year survival in coronary artery bypass grafting patients (2001 to 2003) at a low-volume hospital (n = 504; 160 per year [median]) versus a high-volume hospital (n = 1,410; 487 per year) served by the same high-volume surgeon team. Covariate risk adjustment was done via multivariate and propensity modeling. RESULTS: The two hospital cohorts exhibited multiple demographic and risk factor differences. Unadjusted low-volume hospital vs high-volume hospital operative mortality was similar overall (2.38% vs 2.98%; p = 0.59) with nearly identical Society of Thoracic Surgeons observed-to-expected ratios (0.83 vs 0.82), irrespective of preoperative risk category. Hospital volume did not predict operative mortality (odds ratio, 95% confidence interval = 0.82; p = 0.602). At follow-up, a total of 28 low-volume hospital deaths (5.6%) and 135 high-volume hospital deaths (9.6%) occurred at similar surgery-to-death intervals (p = 0.7). Unadjusted 0 to 3-year survival was significantly worse for high-volume hospitals (risk ratio = 1.59; 1.06 to 2.39; p = 0.026). Yet procedure volume was not independently associated with worse midterm survival after covariate (risk ratio = 1.28; 0.84 to 1.96; p = 0.247) or propensity score (risk ratio = 1.11; 0.72 to 1.71; p = 0.648) adjustment. CONCLUSIONS: Hospital and surgeon volume effects on coronary artery bypass grafting outcomes are interdependent, and therefore hospital coronary artery bypass grafting volume per se is not a reliable marker of quality. Instead, outcome quality markers should rely on thorough risk-adjustment based on detailed clinical databases, possibly including annual and cumulative surgeon volume.
Aged↗
The effect of prompt physician visits on intensive care unit mortality and cost.
OBJECTIVE: To determine the effect on mortality, length of stay, and direct variable cost of physician response time to seeing patients after intensive care unit admission. DESIGN: Retrospective analysis of the intensive care unit database. SETTING: Medical center. PATIENTS: Subjects were 840 patients who had complete direct variable cost data and a subset of 316 patients who were matched by propensity scores. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Median time to first visit by a physician was 6 hrs. One hundred thirty-five patients (16.1%) died in hospital compared with 25.0% predicted by Acute Physiology and Chronic Health Evaluation risk (p < .001). Higher Acute Physiology and Chronic Health Evaluation risk, older age, mechanical ventilation on arrival in the intensive care unit, and longer time until seen by a physician were predictors of hospital mortality. Each 1-hr delay in seeing the patient was associated with a 1.6% increased risk of hospital death, which further increased to 2.1% after including propensity score. However, patients seen more promptly (<6 vs. >6 hrs) had greater hospital direct variable cost ($11,992 +/- $12,043 vs. $10,355 +/- $10,368, p = .04), before controlling for acuity of illness and other factors that may have affected time to evaluation. In the subpopulation of propensity-matched patients, patients seen promptly (<6 vs. >6 hrs) had shorter hospital length of stays (11 +/- 11 vs. 13 +/- 14 days, p = .03) but similar direct variable costs ($10,963 +/- 10,778 vs. $13,016 +/- 13,006, p = .16) and similar mortality rates (24 vs. 30, p = .46). CONCLUSIONS: In the total patient population, delay in seeing patients was associated with an increased risk of death. In the propensity-matched patients, promptly seen patients had shorter hospital stays but similar direct variable costs.
APACHE↗
Role of hemodilutional anemia and transfusion during cardiopulmonary bypass in renal injury after coronary revascularization: implications on operative outcome.
OBJECTIVE: Acute renal injury and failure (ARF) after cardiopulmonary bypass (CPB) has been linked to low on-pump hematocrit (hematocrit). We aimed to 1) elucidate if and how this relation is modulated by the duration of CPB (TCPB) and on-pump packed red blood cell transfusions and 2) to quantify the impact of post-CPB renal injury on operational outcome and resource utilization. DESIGN: Retrospective review. SETTING: A Northwest Ohio community hospital. PATIENTS: Adult coronary artery bypass surgery patients with CPB but no preoperative renal failure. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: We quantified post-CPB renal injury via 1) the peak postoperative change in serum creatinine (Cr) level relative to pre-CPB values (%DeltaCr) and 2) ARF, defined as the coincidence of post-CPB Cr > or =2.1 mg/dL and >2 times pre-CPB Cr. The separate effects of lowest hematocrit, intraoperative packed RBC transfusions, and TCPB on %DeltaCr and ARF were derived via multivariate regression, overlapping quintile subgroup analyses, and propensity matching. Lowest hematocrit (22.0% +/- 4.6% sd), TCPB (94 +/- 35 mins), and pre-CPB Cr (1.01 +/- 0.23 mg/dL) varied widely. %DeltaCr varied substantially (24 +/- 57%), and ARF was documented in 89 patients (5.1%). Both %DeltaCr (p < .001) and ARF (p < .001) exhibited sigmoidal dose-dependent associations to lowest hematocrit that were 1) modulated by TCPB such that the renal injury was exacerbated as TCPB increased, 2) worse in patients with relatively elevated pre-CPB Cr (> or =1.2 mg/dL), and 3) worse with intraoperative packed red blood cell transfusions (n = 385; 21.9%), in comparison with patients at similar lowest hematocrit. Operative mortality (p < .01) and hospital stays (p < .001) were increased systematically and significantly as a function of increased post-CPB renal injury. CONCLUSIONS: CPB hemodilution to hematocrit <24% is associated with a systematically increased likelihood of renal injury (including ARF) and consequently worse operative outcomes. This effect is exacerbated when CPB is prolonged with intraoperative packed red blood cell transfusions and in patients with borderline renal function. Our data add to the concerns regarding the safety of currently accepted CPB practice guidelines.
Acute Kidney Injury↗
Evaluation of capnography using a genetic algorithm to predict PaCO2.
INTRODUCTION: Noninvasive estimates of Paco(2) are usually done by measuring exhaled carbon dioxide at end-expiration (Petco(2)). While commonly used in studies involving healthy patients, it is less useful in sicker patients. Conditions that affect the terminal dead space and hence the accuracy of Petco(2) as a surrogate for Paco(2) may also affect other components of the capnogram. A genetic algorithm is a computer technique for discovering relationships between variables. The purpose of this study was to use a genetic algorithm to improve the precision of Paco(2) prediction in comparison to Petco(2). METHODS: Inspiratory and expiratory volumes were measured and analyzed by the computerized capnogram. Data were recorded for 2 min. Within 5 min of recording the capnograms, arterial blood gases were obtained. After excluding artifact and incomplete capnograms, five of the remaining breaths from each patient were selected. A genetic algorithm, constructed in postfix notation, consisted of 1,000 chromosomes with genes randomly selected from the 11 capnographic data fields and mathematical operators. The algorithm was constructed on 400 breaths from 83 randomly selected patients (construction group) and tested on 160 breaths from the remaining 32 patients (test group). RESULTS: For the construction group, the bias and precision between Petco(2) and Paco(2) were 4.3 +/- 4.9 mm Hg (mean +/- SD). For the 160 breaths in the test group, Petco(2) predicted Paco(2) with bias and precision of 2.9 +/- 4.2 mm Hg. The best chromosome found by the genetic algorithm was (10 x 5 + 5 x 5 x 5)/(10 x 10) x Petco(2) - (5 x 5 x 10 + 5 x 5)/(10 x 10) x int time + 2 x 2 x 2 x 2 + (2 x 2)/10, which reduces to 0.65 x Petco(2) - 2.75 x int time + 16.4. This produced a bias and precision of 0.9 +/- 4.1 mm Hg in the construction group and 0 +/- 3.7 mm Hg in the test group (p < 0.01). CONCLUSIONS: In this study of nonintubated emergency department patients, a genetic algorithm produced an improvement in bias and precision of Paco(2) prediction.
Adult↗
Comparison of cardiac output determined by bioimpedance, thermodilution, and the Fick method.
BACKGROUND: Cardiac output can be determined by using a variety of methods. OBJECTIVES: To determine the precision and bias between 3 methods for determining cardiac output: bioimpedance, thermodilution, and the Fick method. METHODS: Cardiac output was determined by using bioimpedance via neck and thorax patches and thermodilution via pulmonary artery catheter in 46 patients in the intensive care unit. A subset of 15 patients also had cardiac output determined by using the Fick method. RESULTS: Mean (SD) cardiac output in all patients was 6.3 (2.2) L/min by thermodilution and 5.6 (2.0) L/min by bioimpedance. In the 15 patients in whom all 3 methods were used, mean cardiac output was 6.0 (1.7) L/min by thermodilution, 5.3 (1.7) L/min by bioimpedance, and 8.6 (4.5) L/min by the Fick method. Bias and precision (mean difference +/- 2 SDs) were 0.7 +/- 2.9 L/min between thermodilution and bioimpedance, 1.7 +/- 3.8 L/min between the Fick method and thermodilution, and 2.4 +/- 4.7 L/min between the Fick method and bioimpedance. CONCLUSION: Bioimpedance, thermodilution, and Fick determinations of cardiac outputs are not interchangeable in a heterogeneous population of critically ill patients.
Aged↗
Hospital and long-term outcome of trauma patients with tracheostomy for respiratory failure.
Studies of tracheostomy for respiratory failure have suggested a poor prognosis, however, trauma patients may have a better outcome. Data from 113 trauma patients were retrospectively analyzed for comorbidities, laboratory values, and hospital course. Long-term survival was determined from the Social Security Death Index. Trauma patients were young, overwhelmingly male, relatively healthy, and frequently uninsured. Seventy-five per cent of trauma patients were liberated from mechanical ventilation by hospital discharge. Timing of tracheostomy had no effect on days of mechanical ventilation or hospital length of stay. Hospital survival was 98 per cent, and 3-year Kaplan-Meier survival was 80 per cent. Older age and higher admission creatinine levels were predictive of late death. Trauma patients who undergo tracheostomy are likely to survive and be liberated from mechanical ventilation.
Adult↗
Effects of intraaortic balloon augmentation in a porcine model of endotoxemic shock.
OBJECTIVE: Patients with septic shock commonly have myocardial dysfunction associated with lactic acid production and troponin I release. The purpose of this study was to evaluate the effects on intraaortic balloon pump (IABP) support on myocardial dysfunction. DESIGN: Prospective, randomized controlled study. SETTING: Animal research laboratory. METHODS: Ten pigs had arterial, pulmonary arterial, and coronary catheters inserted. After receiving endotoxin infusion over 30 min, half the animals received IABP support. RESULTS: Coronary sinus lactic acid levels (P< 0.05 for both 90 min versus baseline and 60 min versus baseline) and arterial lactic acid levels (P < 0.05 for both 90 min versus baseline and 60 min versus baseline) increased with time but did not differ between IABP and sham groups. While overall there was no difference with time in myocardial lactic acid consumption or production (calculated as arterial lactic acid level minus coronary sinus lactic acid level), the IABP group showed net myocardial lactic acid consumption at 90 min, while the sham group showed myocardial lactic acid production. Three of five animals in each group showed troponin I release. The levels were similar and did not differ between groups. CONCLUSION: IABP had no benefits in this porcine model of endotoxemic shock.
Animals↗
Hospital and long-term outcome after tracheostomy for respiratory failure.
OBJECTIVE: To determine the patient characteristics, hospital course, hospital cost, posthospital survival, and functional outcome in a group of patients with tracheostomy for respiratory failure. DESIGN: Retrospective chart review combined with prospective evaluation of functional status. SETTING: An urban, tertiary-care medical center. PATIENTS: Adult patients with tracheostomy for respiratory failure between January 1, 1998, and December 31, 2000. METHODS: Retrospective chart review and prospective administration of the Short Form-36 (SF-36) for health status outcome. RESULTS: Four hundred twenty-nine patients were studied. Hospital mortality was 19%. Only 57% of survivors were liberated from mechanical ventilation. At 100 days, 6 months, 1 year, and 2 years after discharge, 24%, 30%, 36%, and 42% of hospital survivors had died, respectively. Patients liberated from mechanical ventilation and having their tracheostomy tubes decannulated had the lowest mortality (8% at 1 year); the mortality of ventilator-dependent patients was highest (57%). Sixty-six patients completed the SF-36 for functional status. While emotional health was generally good, physical function was quite limited. Median hospital direct variable cost was $29,340. CONCLUSION: Overall survival and functional status are poor in patients with tracheostomy for respiratory failure. Patients who are liberated from mechanical ventilation and have their tracheostomy tubes removed have the best survival; however, it comes at a higher hospital cost and longer length of stay.
Adult↗
Is a charge a cost if nobody pays it?
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Amiodarone↗
Cost-effectiveness of different postoperative analgesic treatments.
Pain may produce metabolic changes after surgery, which may contribute to further morbidity. A variety of medicines and techniques can be used to successfully treat pain. It is postulated that improved analgesia leads to improved outcomes, although analgesics may also contribute to morbidity. This article reviews the literature evaluating the cost-effectiveness of providing different types of postoperative analgesics and finds that most studies are so poorly conducted that they prevent definitive conclusions being made. The author suggests that further studies be done using analgesics as just one part of a multimodal rehabilitation approach with careful attention to defining outcome, costs and achieving sufficient power to find or exclude meaningful differences.
Analgesics, Non-Narcotic↗
Operative and 5-year outcomes of combined carotid and coronary revascularization: review of a large contemporary experience.
BACKGROUND: Surgical treatment of concomitant coronary and carotid disease is controversial. Studies comparing staged versus combined coronary artery bypass grafting and carotid endarterectomy (CABG/CEA) report varying and often conflicting operative results. Also, few studies have investigated the long-term outcomes of combined surgery. METHODS: We reviewed the operative outcome and 5-year survival results of 189 consecutive patients (69+/-9 years old, 66 [35%] female patients) who underwent combined CABG/CEA between 1994 and 1999. Survival follow-up was conducted in February 2001 and the incidence of late stroke, carotid surgery, and myocardial infarction was investigated in all surviving patients by mail survey. A phone interview was done by a surgeon of patients with late strokes or repeated CEA. RESULTS: Operative death occurred in 5 of 189 patients (2.65%) 4 of which were in-hospital deaths. A total of 5 (2 permanent, 3 transient [2.65%]) perioperative strokes were documented in these patients, and 1 of the perioperative strokes patients died in the hospital. In all, 156 of 189 patients (82.5%) were alive at the time of the study and completed surveys were collected from 153 of 156 patients (98%). Of these 153 patients, 4 reported a late stroke (2.6%), 5 suffered a myocardial infarction (3.3%), and 16 (10.5%) underwent subsequent CEA (7 ipsilateral to original CEA). Angioplasty (3 of 153, 2.0%) and redo surgery (1 of 153, 0.66%) occurred infrequently. Median survival follow-up was 51 months (range 12 to 84), and the corresponding 5-year Kaplan-Meier survival was 79.4%. This survival was similar to that of age-matched isolated CABG patients (n = 532) with documented history of cerebrovascular disease but no surgical carotid lesions. CONCLUSIONS: Our results suggest that combined CABG/ CEA is safe and may in fact reduce the risk of adverse outcomes in the intermediate term compared with age and risk-matched patients. We speculate the latter may be attributable to a cerebrovascular protective effect of CABG/CEA pending verification by randomized trials. An economic benefit of CABG/CEA may also be inferred from avoiding separate coronary and carotid operations and reduction in the high costs of perioperative stroke.
Aged↗
Safe, highly selective use of pulmonary artery catheters in coronary artery bypass grafting: an objective patient selection method.
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.
Aged↗
Cardiac output, coronary blood flow, and blood gases during open-chest standard and compression-active-decompression cardiopulmonary resuscitation.
OBJECTIVE: To determine whether open-chest compression-active-decompression (CAD) could improve cardiac output, coronary blood flow, blood gases, and resuscitation compared to open-chest manual compression in a porcine model of cardiac arrest. DESIGN: Prospective, randomized laboratory investigation for measurement of cardiac output, coronary blood flow, arterial and mixed venous blood gases and potassium levels, and return of spontaneous circulation. SUBJECTS: Ten pigs each weighing approximately 36.4 kg. INTERVENTIONS: Following preparation of the model and opening of the chest, ultrasonic flow probes were placed on the ascending aorta and left anterior descending artery. Cardiac arrest was induced by epicardial pacing. Subjects received either open-chest CAD or open-chest manual compression. After 10 min of arrest, defibrillation was attempted. MEASUREMENTS AND MAIN RESULTS: Cardiac output fell to 46+/-53% (95% CI: -20 to 112) and 41+/-14% (95% CI: 23-59) (P>0.05) of baseline with CAD and manual methods at 5 min after arrest, respectively. Similarly, coronary blood flow fell to 33+/-14% (95% CI: 16-50) and 42+/-16% (95% CI: 22-62) (P>0.05) of baseline at 5 min. Both groups developed similar levels of metabolic acidosis, mixed venous hypoxemia, and hyperkalemia, with potassium levels: 6.5+/-4.0 meq/l (95% CI: 1.6-11.4) at 5 min and 7.5+/-4.6 meq/l (95% CI: 1.8-13.2) at 10 min in the CAD group and 5.8+/-2.0 meq/l (95% CI: 3.4-8.3) at 5 min and 6.1+/-1.4 meq/l (95% CI: 4.4-7.9) at 10 min in the manual group. Levels of hyperkalemia were inversely proportional to the square of PvO(2). One pig in each group was resuscitated after defibrillation. CONCLUSION: We found no benefit using CAD. Both low coronary blood flow and hyperkalemia may have limited resuscitation.
Animals↗
Cost, outcome, and functional status in octogenarians and septuagenarians after cardiac surgery.
STUDY OBJECTIVES: To evaluate cost, outcome, and functional status of octogenarians and septuagenarians after cardiac surgery. DESIGN: Observational case control study. Retrospective analysis of hospital cost and outcome. Prospective analysis of functional status at 1 to 2 years. PATIENTS: One hundred three consecutive octogenarians and 103 randomly selected septuagenarians who underwent cardiac surgery. SETTING: A university-affiliated tertiary care center. MEASUREMENTS AND RESULTS: Compared to septuagenarians, octogenarians were more likely to be widowed (p < or = 0.001) and to have had preoperative strokes (p < or = 0.05) but were less likely to have diabetes mellitus (p < or = 0.001). They were less likely to have undergone mitral valve surgery (p < or = 0.01) but were more likely to have undergone coronary artery bypass graft surgery without cardiopulmonary bypass (p < or = 0.001). The hospital mortality rate was 6% in the younger group and 9% in the older group (odds ratio, 1.5; 95% confidence interval [CI], 0.5 to 4.5; p > 0.05). In patients undergoing isolated CABG, the mortality rate was 1.4% in the septuagenarians and 8.2% in the octogenarians (odds ratio, 6.2; 95% CI, 0.7 to 52.7; p = 0.12). Despite similar ICU, postoperative, and total lengths of stay, the median hospital direct variable cost was 35% higher for the octogenarians. At late follow-up, octogenarians had lower levels of physical functioning and general health but otherwise had levels of function that were similar to those of septuagenarians. CONCLUSION: Cardiac surgery can be performed in the elderly with good hospital and late functional results, but at a higher hospital cost than that for younger patients.
Age Factors↗