Eur J Cardiothorac Surg 2005;27:508-511
© 2005 Elsevier Science NL
The predictors and outcome of recidivism in cardiac ICUs
Hunaid A. Vohra*,
Ira R.A. Goldsmith,
Michael D. Rosin,
Norman P. Briffa,
Ramesh L. Patel
Cardio-thoracic Surgical Unit, Walsgrave Hospital, Clifford Bridge Road, Coventry CV2 2DX, UK
Received 29 July 2004;
received in revised form 18 November 2004;
accepted 22 November 2004.
* Corresponding author. Address: 359, Roding Lane North, Woodford Green, Essex IG8 8LH, UK. Tel./fax: +44 208 551 9914. (E-mail: hunaidvohra{at}yahoo.co.uk).
 |
Abstract
|
|---|
Objective: Reinstitution of step-up care (recidivism) following cardiac surgery may be associated with increased mortality. This has, however, not been widely reported. Methods: We, therefore, studied 8113 consecutive patients who underwent coronary artery bypass grafting (CABG), valve replacement/repair or combined valve+CABG surgery between January 1996 and December 2003 to determine the reasons for readmission to the intensive care unit (ICU) and their outcomes in terms of length of stay in (i) the ICU (ii) hospital and (iii) the in-hospital mortality following recidivism. Results: Of the 7717 patients discharged out of the ICU, 2.3% (182) of patients [mean age 70.4±8.35 years (range 30–90 years); 65.4% (119) males] required step-up care. Recidivism was 1.8% (101 of 5633) following coronary artery by-pass grafting (CABG) and 3.9% (81 of 2084) following valve replacement/repair±CABG (P<0.05). The mean interval from ICU discharge to ICU recidivism was 6.6±8.4 days (range 6h to 28 days). The principal reasons for recidivism were (i) respiratory failure requiring reintubation and ventilation in 54.9% (n=100) of patients (ii) cardiovascular instability (including that secondary to dysrhythmias) and heart failure in 23.1% (n=42) (iii) renal failure requiring haemofiltration in 6.6% (n=12) (iv) sepsis in 1.1% (n=2) (v) cardiac tamponade/bleeding requiring re-exploration in 7.7% (n=14) and (vi) gastro-intestinal complications requiring laparotomy in 6.0% (n=11) patients. Multivariate analysis showed that, during primary ICU stay, respiratory complications, low cardiac output state, dysrhythmias, renal failure requiring haemofiltration and re-exploration for bleeding were independent predictors of recidivism. Following recidivism (i) the mean length of stay in the ICU was 6.65±6.2 days (range 4h to 51 days), (ii) mean hospital stay was 19.2±17.3 days (10–60 days) and (iii) the 30-day in-hospital mortality was 32.4%. Conclusions: Patients are more likely to require recidivism following valve surgery±CABG than CABG alone. Whilst respiratory complications were the most common reasons for recidivism in our study, patients who required mechanical supports to maintain vital functions following surgery were most prone to recidivism. Hence, efforts should be made to treat cardio-respiratory problems early in this group of patients to reduce ICU recidivism.
Key Words: Recidivism • Intensive care unit • Cardiac surgery
|
1. Introduction
|
|---|
Following cardiac surgery the use of ICU facilities varies amongst various institutions. Factors such as the pre-operative health status of the patient, the institutions physical constraints, high costs, individual surgical practice styles and the type of cardiac operation influence the use of ICU facilities following surgery [1]. There is increasing pressure to make ICU beds available for cardiac surgery. This may be achieved my increasing the resources available or reducing the time the patients stay in ICU after cardiac surgery. However, patient care cannot be compromised at any cost. Hence, it is becoming increasingly important to identify patients at high risk of returning to the ICU during the same admission after undergoing cardiac surgery.
Although criteria have been described for discharging patients out of general ICUs [2], there is very limited literature on the successful use of such guidelines on the outcome for patients following cardiac surgery. Since readmission to the ICU may imply that such patients have been discharged prematurely, ICU readmission rates have been proposed as measures of quality indexes [3,4]. In the present cardiac literature, the incidence of recidivism following cardiac surgery and criteria defining patients at high risk of requiring step-up care have not been well described. Hence, the aim of our study was to determine the rate of recidivism at our institution, its relationship with the primary length of stay in the ICU, the principal reasons, the independent predictors leading to its occurrence.
|
2. Materials and methods
|
|---|
2.1. Patient population
From 8113 consecutive adult patients who underwent coronary artery bypass grafting (CABG), valve replacement/repair or combined valve+CABG surgery at our tertiary referral centre between January 1996 and December 2003, a total of 7717 patients who were discharged alive from the cardiac ICU were retrospectively studied. Three hundred and ninety six patients who died in theatre or during their primary ICU stay were excluded. Patients who underwent off-pump coronary artery bypass grafting (OPCAB) were excluded from our study. Although few patients may have been discharged out of ICU in a few hours, generally, fast track surgery is not performed at our institution. Information for the study was obtained from the cardiac surgical Patients Analysis and Tracking System (PATS) database and hospital records. All patients who needed recidivism to the ICU were identified and the yearly rate of recidivism determined. The principal reasons for recidivism, length of stay in the ICU as well as hospital following recidivism, the occurrence of post-operative complications and outcome in terms of mortality were also determined in all patients.
2.2. Statistics
Descriptive statistics were obtained using the package STATISTICA for windows v 4.3, StatSoft Inc. USA. Whilst continuous variables were otherwise compared between groups using the students ‘t’ test, categorical data was compared between the two groups using the Fisher's exact test and 
2-test. To determine the influence of various factors on recidivism, patient variables that were considered to influence outcome were analysed using multiple regression analysis, with recidivism as a dependent variable. A value of P<0.05 was considered significant in all statistical analyses.
|
3. Results
|
|---|
From 7717 patients who were discharged out of the ICU following CABG, valve or combined CABG and valve surgery, 2.3% (182) of patients (65.4% (119) males) required readmission to the ICU. The mean age of patients requiring readmission to ICU was 70.4±8.35 years (range 30–90 years) and not significantly different from those who did not require readmission [mean age 66.2±7.5 years (range 29–91 years) (P=0.09)]. Whilst recidivism following CABG was 1.8% (101/5633), recidivism following valve replacement/repair±CABG was significantly higher at 3.9% (81/2084) (P<0.05). Although showing a downward trend, the overall yearly recidivism rate has not changed significantly (Fig. 1).
3.1. Primary length of stay in the ICU and interval to recidivism
The mean length of primary stay in the ICU of patients subsequently requiring recidivism was 2.5±3.4 days (range 5h to 22 days) and longer (although not statistically significant) compared to the primary length of stay of those patients who did not require recidivism, which was 1.6±2.2 days (range 1h to 35 days; P=0.4). Interestingly, as shown in Table 2, the primary length of ICU stay did not have a significant effect on the rate of ICU recidivism in the multiple regression analysis. The mean interval from ICU discharge to ICU recidivism was 6.6±8.4 days (range 6h to 28 days).
3.2. Causes of recidivism
Although some patients may have had multiple complications we classified the causes of recidivism on the basis of the prinicipal complication that lead to readmission to the ICU. Respiratory complications requiring re-intubation and ventilation lead to 54.9% (n=100) of readmissions to the ICU (Table 1). These included hospital-acquired and aspiration pneumonia, inability to clear secretions and poor ventilatory reserve leading to hypoxia or ventilatory failure. Cardiovascular instability (includes that secondary to dysrythmias) and heart failure, contributed to 23.2% (n=42) of the recidivism patients. For the purpose of this study, cardiac dysrhythmias include new-onset atrial fibrillation, supraventricular tachycardia and ventricular tachycardia/fibrillation. The breakout of rest of the causes is shown in Table 1.
3.3. Outcome following recidivism
- (i) Length of ICU and hospital stay. The mean length of stay in the ICU following recidivism was 6.65±6.2 days (range 4h to 51 days), whilst the mean length of hospital stay following recidivism was 19.2±17.3 days (range 10–60 days). The mean length of hospital stay of patients who did not require recidivism was 8.2±7.3 days (range 4–122 days; P<0.05).
- (ii) 30-day hospital mortality. The hospital mortality in patients requiring ICU recidivism was significantly higher compared to those patients who did not require such care, 32.4% (n=59/182) versus 2.05% (n=155/7535; P=<0.05).
3.4. Predictors of recidivism
Multiple regression analysis showed that previous history of myocardial infarction (P<0.01) was the only independent pre-operative risk factor for recidivism. During the primary post-operative ICU stay (i) respiratory problems (P<0.00001), (ii) low cardiac output state requiring post-operative intra-aortic counterpulsation (P<0.00001), (iii) cardiac dysrhythmias (P<0.003), (iv) renal failure requiring hemofiltration (P<0.003) and (v) re-exploration for bleeding (P<0.02) were independent predictors of recidivism (Table 2). Also, combined CABG+valve surgery emerged as an independent predictor of ICU recidivism (P=0.01).
|
4. Discussion
|
|---|
The ICU recidivism rate of 2.3% in our cardiac surgical tertiary referral centre is well within the previously described rates of 6% (range 5–14%) for general medical and surgical ICUs [5–9] and 5.5% following cardiac surgery [10]. Whilst a high ICU recidivism rate may be due to a low threshold for institution of step-up care, ICU recidivism is generally perceived to reflect either inadequate quality of care of patients or premature discharge of patients out of the ICU [11]. Nevertheless, there is no evidence to suggest that ICU recidivism is reduced by longer primary ICU stay or that ICU recidivism increases in the presence of severe shortage of ICU beds when patients may be transferred out of the ICU prematurely [12]. The results of our multifactorial analysis concurs with the current notion that longer primary length of ICU stay is not related to the risk of recidivism.
The age of patients has shown to influence the readmission rates to general intensive care units [5,13]. However, our study in a cardiac ICU setting coincides with the experience described by Cohn and colleagues [10] that age does not significantly influence cardiac ICU recidivism. Whilst hospital-acquired pneumonia, aspiration pneumonia, inability to clear secretions and poor ventilatory reserve resulting in hypoxia and respiratory failure accounted for the majority of readmissions to the ICU, cardiovascular instability and heart failure were also a common cause for ICU recidivism at our centre. ‘Cardiovascular instability (including that secondary to dysrhythmias) and heart failure’ is considered as one group (cardiac) of causes of recidivism for the purpose of this study to differentiate from ‘respiratory’ causes. Although treatment may be different within the group, this was done to avoid the distribution of incorrect data as it may be extremely difficult to classify primary cardiac dysfunction, arrythmogenic dysfunction and heart failure (in the setting of ICU readmission) separately in a retrospective study like this. Although inspiratory capacity measurements has been shown to be a sensitive indicator for readmission to ICU following liver transplant and an abnormal chest X-ray before their initial ICU discharge have been shown to be associated with recidivism [14], ours is the only study to describe independent predictors of ICU readmission following cardiac surgery. Indeed, multiple regression analysis suggested that following surgery, patients requiring mechanical support to maintain vital functions, for example, ventilation for >24h, postoperative intra-aortic balloon pump (IABP) for low cardiac output state and haemofiltration for renal failure were most likely to require readmission to the ICU following their primary discharge. Also, patient characteristics of a previous history of myocardial infarction, postoperative dysrythmias during primary ICU stay and re-exploration for bleeding were independent predictors of recidivism. The finding that combined CABG+valve surgery is an independent predictor of ICU recidivism is not surprising as these patients are generally higher risk for cardiac surgical morbidity and mortality. Many of these patients possess a poor left ventricular ejection fraction and are in heart failure with pulmonary congestion. Such patients may require closer observation and deserve a lower threshold for initiation of more intense nursing and respiratory, cardiac and renal pharmacologic support on the HDU and the ward than other patients.
In the present study a majority of patients were readmitted to the ICU within the first week after discharge from ICU. Thus, in this time interval any cardio-respiratory deterioration of patients in the high dependency unit (HDU) or ward, especially in those patients who have initially required mechanical support to maintain breathing and circulation, should be managed promptly. Effective analgesia and intense respiratory physiotherapy for patients with respiratory complications have been associated with decreased morbidity and hospital mortality [15] and may help considerably to avoid subsequent ICU recidivism.
Since ICU recidivism is associated with a high mortality and longer length of stay in the hospital, as suggested by our study and previous reports [5,6,16] it is encouraging to note no deterioration in yearly rate of ICU readmission in our unit which is well within the published incidence reported in the literature. However, while it is important to avoid recidivism, it is equally important to ensure that recidivism is not delayed for too long before irreversible damage occurs. Likewise, once recidivism occurs, every effort should be made to avoid the associated high mortality. It is important to learn from this large series and one may need to rethink clinical strategies as discussed above to offer cardiac surgery of the highest quality. Further investigation into the influence of factors such as the patients' physiologic reserve, mode of admission, availability of ICU beds, the quality of care in the post-surgical cardiac wards and their influence on ICU recidivism is required. Whilst the use of standard protocols [17,18] and scores [2] for the discharge of patients out of the ICU may influence ICU recidivism, the effectiveness of these following cardiac surgery remains to be established.
|
References
|
|---|
- Mazer CD, Byrick RJ, Sibbald WJ. Postoperative utilization of critical care services by cardiac surgery: a multicenter study in the Canadian healthcare system. Crit Care Med 1993;21:851-859.[Medline]
- Society of Critical Care Medicine Task Force on Guidelines Recommendations for intensive care unit admission and discharge criteria. Crit Care Med 1988;16:807-808.[Medline]
- Brook RH, Lohr KN. Monitoring quality of care in the mediprogram: two proposed systems. J Am Med Assoc 1987;258:3138-3141.[CrossRef][Medline]
- Holloway JJ, Thomas JW. Factors influencing readmission risk: implications for quality monitoring. Health Care Financ Rev 1989;11:19-32.[Medline]
- Cooper GS, Sirio CA, Rorondi AJ. Are readmissions to the intensive care unit a useful measure of hospital performance?. Med Care 1999;37:399-408.[CrossRef][Medline]
- Durbin Jr CG, Kopel RF. A case-control study of patients readmitted to the intensive unit. Crit Care Med 1993;21:1547-1553.[Medline]
- Franklin C, Jackson D. Discharge decision-making in a medical ICU: characteristics of unexpected admissions. Crit Care Med 1983;11:61-66.[Medline]
- Baigelman W, Katz R, Geary G. Patient readmission to critical care units during the same hospitalization at a community teaching hospital. Intensive Care Med 1983;9:253-256.[CrossRef][Medline]
- Snow N, Bergin KT, Horrigan TP. Readmission of patients to the surgical intensive care unit: patient profiles and possibilities for prevention. Crit Care Med 1985;13:961-964.[Medline]
- Cohn WE, Selke FW, Sirois C, Lisbon A, Johnson RG. Surgical ICU recidivism after cardiac operations. Chest 1999;116:688-692.[Abstract/Free Full Text]
- Angus DC. Grappling with intensive care unit quality: does the readmission rate tell us anything [editorial]?. Crit Care Med 1998;26:1779-1780.[Medline]
- Strauss MJ, LoGerfo JP, Yeltazie JA. Rationing of intensive care unit services: an everyday occurrence. J Am Med Assoc 1986;255:1143-1146.[Abstract]
- Rubins HB, Moskowitz MA. Discharge decision-making in a medical intensive care unit: identifying patients at high risk of unexpected death or unit readmission. Am J Med 1988;84:863-869.[CrossRef][Medline]
- Levy MF, Greene L, Ramsay MA, Jennings LW, Ramsay KJ, Meng J, Hein AH, Goldstein RM, Husberg BS, Gonwa TA, Klintmalm GB. Readmission to the intensive care unit after liver transplantation. Crit Care Med 2001;29:18-24.[CrossRef][Medline]
- Kirby EG, Durbin CG. Establishment of a respiratory assessment team is associated with decreased mortality in patients re-admitted to the ICU. Resp Care 1996;41:903-907.
- Franklin C, Rackow EC, Mamdani B. Triage consideration in medical intensive care. Arch Int Med 1990;150:1455-1459.
- Kollef MH, Shapiro SD, Silver P. A randomized, controlled trial of protocol-directed versus physician-directed weaning from mechanical ventilation. Crit Care Med 1997;25:567-574.[CrossRef][Medline]
- Beggs V, Birkemeyer N, Nugent W. Factors related to rehospitalization within thirty days of discharge after coronary artery bypass grafting. Best Pract Benchmarking Health 1996;1:180-186.
Top
Abstract
1. Introduction
