|Year : 2015 | Volume
| Issue : 4 | Page : 213-216
Prolonged intensive care unit stay after coronary artery bypass graft surgery: Role of perioperative factors
Babatunde Babasola Osinaike1, Babatunde Okikiolu2, Oluyemisi Olusesin3
1 From the Department of Anaesthesia, University College Hospital; Department of Anaesthesia, College of Medicine, University of Ibadan, Ibadan, Nigeria
2 From the Department of Physiotherapy, University College Hospital, Ibadan, Nigeria
3 From the Department of Nursing, University College Hospital, Ibadan, Nigeria
|Date of Web Publication||14-Jan-2016|
Babatunde Babasola Osinaike
From the Department of Anaesthesia, University College Hospital; Department of Anaesthesia, College of Medicine, University of Ibadan, Ibadan
Source of Support: None, Conflict of Interest: None
Introduction: Long stay in the Intensive Care Unit (ICU) after coronary artery bypass graft (CABG) surgery has been found to result in increased hospital mortality, poor long-term prognosis, prolonged hospital stay, and consequently, high cost and expenses. We, therefore, reviewed CABG surgery performed at the Madras Medical Mission Chennai, India, during a 3-month period to determine perioperative factors that are significant predictors of prolonged ICU admission.
Methods: We retrospectively studied patients who had elective CABG surgery from November 2008 to January 2009. Information about the following perioperative variables were retrieved; patient demographics, history of co-morbid disease, pre-operative left ventricular (LV) function, the number of coronary vessels grafted, duration of bypass, the level of cardiovascular support post-bypass, the need for surgical re-exploration and duration of stay in the ICU. Prolonged ICU admission was defined as stay over 4 days after elective CABG surgery.
Results: A total of 194 patients were reviewed, with males accounting for 84%, age ranged from 32 to 80 years, and duration of stay in the ICU from 2 to 14 days, with mean values of 58.06 ± 8.48 years and 3.96 ± 1.60 days, respectively. Univariate analysis showed significant differences in the number of patients with pulmonary hypertension (P = 0.002), mean bypass time (P = 0.018), requirement for LV support with inotrope (P = 0.021) and surgical re-exploration (P = 0.016) when patients with ICU stay ≤4 days were compared to those with stay over 4 days. Multiple regression revealed only LV support (β =0.69; P = 0.003) as the independent predictor of prolonged ICU stay.
Conclusion: This review showed LV support with inotrope as the only independent predictor of prolonged ICU stay after CABG surgery. Therefore, an excellent perioperative care leading to a reduced requirement for LV support after cardiopulmonary bypass for CABG surgery should be the goal.
Keywords: Coronary artery bypass graft, Intensive Care Unit, length of stay
|How to cite this article:|
Osinaike BB, Okikiolu B, Olusesin O. Prolonged intensive care unit stay after coronary artery bypass graft surgery: Role of perioperative factors. Niger Postgrad Med J 2015;22:213-6
|How to cite this URL:|
Osinaike BB, Okikiolu B, Olusesin O. Prolonged intensive care unit stay after coronary artery bypass graft surgery: Role of perioperative factors. Niger Postgrad Med J [serial online] 2015 [cited 2018 Oct 18];22:213-6. Available from: http://www.npmj.org/text.asp?2015/22/4/213/173968
| Introduction|| |
Coronary artery bypass graft (CABG) surgery remains a very important procedure for patients with narrowed coronary artery (ies) either as a result of multiple vessel disease or following failed percutaneous intervention (s). It basically involves replacing the narrowed portions of the vessels with venous or arterial grafts while the patient is connected to cardiopulmonary bypass (CPB) machine or sometimes done off-pump.
Most of these patients have advanced heart disease (New York Heart Association functional Class III and IV), in addition to some co-existing diseases such as diabetes and chronic renal disease. This makes intensive care after CABG a standard component of the treatment for most of these patients. Factors such as age, gender, hospital admission prior to surgery, the number of grafts and CPB time have variously been identified by many authors as determinants of Intensive Care Unit (ICU) length of stay (LOS) after CABG surgery. ,, Identifying these factors will allow for proactive steps aimed at preventing or reducing the risk of development of such identified modifiable factors in patients scheduled for CABG surgery. Long stay in the ICU has been found to result in increased hospital mortality, poor long-term prognosis, high morbidity,  prolonged hospital stay, and consequently, increased cost and expenses.  Furthermore, it may lead to undue occupation of ICU beds leading to a lengthening of waiting list and cancellation of other elective cardiac operations. We, therefore, conducted a review of CABG procedures done at the Madras Medical Mission, Chennai, India over a 3-month period to determine factors that are significant predictors of two prolonged ICU admission.
| Methods|| |
Approval was obtained from the head of surgery who doubled as the Medical Director to retrospectively study a total of 194 patients who had elective CABG surgery from November 2008 to January 2009. Patients who underwent CABG surgery combined with a heart valve repair or replacement, resection of a ventricular aneurysm or other surgical procedures were excluded. Anaesthesia and analgesia were standardised for all patients as per institutional protocol; this included the use of opioids, midazolam, isoflurane and other indicated drugs with complete cardiovascular monitoring. The surgical approach was by median sternotomy and mild hypothermia (32-34°C) was applied during CPB. Standardised weaning and extubation protocol were employed in all patients by the nursing team and respiratory therapists being part of the unit protocol.
Information about the following perioperative variables were retrieved; patient demographics, history of co-morbid disease, pre-operative left ventricular (LV) function, the number of coronary vessels grafted, duration of bypass, the level of cardiovascular support post bypass, the need for surgical re-exploration and duration of stay in the ICU.
Patients were grouped into two; those with ICU stay ≤4 days, and those with stay over 4 days based on initial analysis of our data that revealed the average duration of ICU admission as 4 days. Prolonged ICU stay was defined as a stay over 4 days after elective CABG surgery. Duration of bypass is the time from commencement to the end of CPB.
LV dysfunction was graded based on the ejection fraction (EF) as adequate >50% or inadequate <50%. Furthermore, cardiovascular support was classified as with support or without support, based on the need for drugs and/or devices to maintain systolic blood pressure at or above 90 mm Hg, central venous pressure below 12 mm Hg or pulmonary capillary wedge pressure below 15 mm Hg immediately after bypass. The number of grafted vessels was classified as ≤3 or >3, while the duration of bypass was graded as ≤90 min or >90 min.
Data analysis was performed with SPSS version 17 software (Chicago IL, USA). The numerical variables were presented as mean ± standard deviation, while the categorised variables were summarised as absolute frequencies and percentages. The continuous variables were compared using the Student's t-test, and the categorical variables were compared using the Chi-square test. The perioperative variables with P < 0.05 after univariate analysis were then subjected to multiple regression analysis to determine independent predictors of prolonged ICU stay.
| Results|| |
A total of 194 patients were involved in this review, males accounted for 84%. Patients' age ranged from 32 to 80 years with a mean value of 58.06 ± 8.48 years and duration of stay in the ICU ranged from 2 to 14 days with a mean value of 3.96 ± 1.60 days. [Table 1] shows univariate analysis of perioperative variables according to the ICU LOS. The number of patients with pulmonary hypertension (P = 0.002), the requirement for LV support with inotrope (P = 0.021) and surgical re-exploration (P = 0.016) were significantly different between those with duration of ICU stay ≤4 days and those >4 days.
|Table 1: Perioperative profile of patients according to the ICU length of stay|
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Though we did not find a statistical difference in the number of patients with bypass time < 90 min compared to those with over 90 min in the prolonged ICU stay group (P = 0.34), the mean bypass time was significantly longer in those patients with prolonged ICU stay (99.71 ± 36.30 vs. 86.33 ± 34.88; P = 0.02) [Table 1].
Multiple regression analysis revealed LV support with inotrope as an independent predictor of prolonged ICU stay (Regression coefficient, β =0.69, P = 0.003) [Table 2].
|Table 2: Multiple regression analysis of predictors of prolonged ICU stay|
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| Discussion|| |
This study reviewed perioperative factors and found LV support as an independent predictor of prolonged stay of more than 4 days in the ICU after CABG surgery. In addition, pre-operative history of pulmonary hypertension, longer bypass time and need for surgical re-exploration were associated with prolonged ICU stay. This is in agreement with many reports published on the impact of perioperative factors on duration of ICU and/or hospital stay after CABG. ,,, This becomes really important in view of the need to reduce the overall cost of care and also make the ICU beds available for other patients. An author opined that prolonged ICU stay can impact on the operating theatre economics.  The inability to offer operative treatment to more patients because of unavailability of ICU beds may lead to cancellation of operation lists and theatre staff may be underemployed. Ghotkar et al. suggested a mixture of patients with a high and low probability of prolonged ICU stay to avoid the possibility of blocking beds in the ICU. 
Different factors have been implicated in many studies as being responsible for prolonged stay in the ICU after CABG surgery. Comparisons between these studies are often difficult because of the disparity in the type and number of independent variables analysed in the different studies. Furthermore, the use of different cut-offs to define a prolonged stay in the ICU (from 2 to 14 days) has contributed to this difficulty. ,,
In agreement with our study, Azarfarin et al.  in a recent study that employed similar cut-off of 4 days (96 h) to define prolonged ICU stay concluded that CPB time and LV support with inotrope were among other factors strongly related to prolonged ICU stay. Michalopoulos et al.  and Hein et al.  in a similar study opined that inotrope use for LV support remained a major predictor of prolonged stay in the ICU. This has been attributed to a high number of open cardiac surgical patients presenting with low cardiac output syndrome (LCOS) in the early post-operative period.  LCOS is a clinical condition that is caused by a transient decrease in systemic perfusion secondary to myocardial dysfunction. It follows an imbalance between oxygen delivery and oxygen consumption at the cellular level which leads to metabolic acidosis.
The long duration of bypass, especially >120 min have been shown in some studies ,,,, to be strongly related to prolonged stay in the ICU after CABG surgery. Mounsey et al.  was of the opinion that CPB time may not be a suitable predictor of ICU stay because this time cannot be suitably predicted or determined until after surgery and may be affected by technical difficulty or skill of the operator. This review showed that intra-operative and post-operative factors played significant roles in determining the duration of ICU stay after CABG surgery compared to pre-operative factors. Previous studies had shown that pre-operative variables such as recent myocardial infarction, age, smoking, EF and the presence of co-morbidities were associated with ICU stays of longer than 2 days. 
Michalopoulos et al. in agreement with our study opined that intra-operative challenges play a significant role in determining the length of ICU stay, and these challenges are often difficult to predict with pre-operative variables. These include factors such as inadequate revascularization, low cardiac output related to systemic inflammatory response syndrome, stunned myocardium, or inadequate myocardial protection during bypass. However, when identified pre-operative factors include a variable such as low EF, the post-operative outcome may not necessarily be poor because revascularisation may be lead to improved myocardial function. Zaroff et al.  reported that though pre-operative low EF is a predictor of poor immediate post-operative outcome after CABG surgery, not all such patients will require inotropic support post-operatively.
In this study, we found that a significantly longer bypass time in patients with prolonged ICU stay. It has been previously established that long bypass time may not only predispose to the need for inotropic support following a longer period of systemic anti-inflammatory response syndrome  but may also lead to excessive primary haemorrhage requiring re-exploration because of CPB-induced haemostatic defect.  Our study has shown that LV support after bypass for CABG surgery is an independent predictor of prolonged ICU stay of more than 4 days. An efficient perioperative care leading to a good recovery of the left ventricle after cardiopulmonary bypass during CABG surgery should, therefore, be the goal. It is hoped that this review will offer clinicians the opportunity to efficiently plan for CABG procedures and allocate resources, being guided by identified risk factors.
We appreciate the support of members of staff of the Department of Anaesthesia, Cardiopulmonary Rehabilitation and Medical Records, Madras Medical Mission, Chennai, India during the conduct of this study.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2]