1. Nepal Medical College and Teaching Hospital (NMC), Nepal: diackmarie3@gmail.com
2. Nepal Medical College and Teaching Hospital (NMC), Nepal: steward001@gmail.com
3. Nepal Medical College and Teaching Hospital (NMC), Nepal: parshukirby88@outlook.com

*             Correspondence: diackmarie3@gmail.com

Keywords: predisposing factors, cardiac resection, re-procedure

1. INTRODUCTION

Up to 5% of patients having heart surgery need chest re-exploration during the first postoperative phase [1]. The primary signs and symptoms are bleeding, cardiac arrest, and hemodynamic instability (clinical suspicion of cardiac tamponade) [2,3]. Higher patient morbidity (sepsis, arrhythmia, decreased cardiac output, kidney failure, prolonged mechanical ventilation, longer ICU/hospital stay) and higher resource consumption are linked to postoperative bleeding [4,5]. Either coagulopathic or surgical causes may be the cause of the bleeding [6]. A number of patient features, including as high age, low BMI, length of stay on ECC, five or more anastomoses, and/or requirement for non-elective surgery, have also been recognized as risk factors for re-examination [7]. This study’s primary goal was to identify the risk variables for re-exploration and its most common cause by using propensity score matching. Evaluating the relationship between re-exploration and death and readmission to the intensive care unit were secondary goals.

2. MATERIALS AND METHODS

In 2019, a retrospective observational study was carried out on a consecutive cohort of patients receiving cardiac surgery in the United States. The procedures included complex aortic surgery, routine coronary surgery (both on-pump and off-pump), valve replacements, congenital heart defects, and post-infarction complications. Individuals undergoing transcatheter aortic valve replacement were not included. Our center does not perform heart transplants. Our center adheres to the guidelines and recommendations of the European Associations of Cardiothoracic Surgery and Cardiothoracic Anesthesiology [8] for pre-operative antiplatelet and anticoagulation management, transfusion, and coagulation protocols. These protocols are informed by the results of thromboelastography and routinely involve the use of cell saver and fibrinogen administration. Examine variables Physicians who were educated for this task and in charge of entering data from our center into the Public Health Service registry collected the data [9]. Prior to surgery, information was obtained regarding the following: the ICU or ward where the procedure would take place; the type of surgery (elective, urgent, or emergency); the preoperative diagnosis; EuroSCORE and SAPS 3 score; age, sex; the NYHA stage; and the history and presence of anemia, antiplatelet or anticoagulation therapy, percutaneous coronary intervention, cardiac surgery, obesity, hypertension, COPD, severe pulmonary hypertension, AMI, congestive heart failure, peripheral vascular disease, stroke, or kidney failure (creatinine > 1.2 mg/dl). Surgical procedures were classified as elective when scheduled in advance, urgent when needed to be done within 24 to 48 hours, and emergency when quick action was needed. Intraoperative data were obtained about circulatory arrest, aortic crossclamp time, ECC time, and any significant bleeding (transfusion of at least 4 units RBC). The number and reason for re-explorations, the duration of mechanical ventilation, the length of ICU stay for re-explored patients, and complications, such as cardiogenic shock, perioperative myocardial infarction, sternal dehiscence, sepsis, multiple organ failure, stroke, mechanical ventilation > 24 hours, and/or renal replacement therapy (continuous or intermittent dialysis), were all recorded after surgery. As outcome variables, data on death and the requirement for ICU readmission were also gathered. For qualitative variables in a descriptive study, absolute (n) and relative (%) frequencies were determined. For qualitative variables, the Fisher exact test or Pearson’s chi-square test were used, depending on the situation. After developing a multivariate logistic regression model, factors that showed statistical significance in the bivariate analysis (p < 0.05) were included.

3. RESULTS AND DISCUSSION

Of the patients, 62.9% had a history or presence of hypertension; 46.9% had dyslipidemia; 32.3% had obesity; 29.5% had diabetes; 24% had chronic renal disease; 15.4% had an AMI; 12.5% had COPD; and 11.5% had severe pulmonary hypertension. Of the patients, 32.4% were in NYHA III–IV and 67.7% were in NYHA I–II prior to surgery. In 73% of cases, the surgery was elective; in 22.6%, it was urgent; and in 4.4%, it was emergency. In 5.4% of cases (n = 116), re-exploration was carried out. Of the 116 patients that were reexamined (Table 1), 56 percent were men, and 86.2% had previously undergone urgent or elective surgery, with valve or aortic surgery being performed in 96.6% of the instances. In the multivariate analysis, valvular/aortic surgery (OR 4.366; 95% CI 1.358-14.034), obesity (OR 1.680; 95% CI 1.11-2.53), pre-surgical diagnosis of endocarditis (OR 2.636; 95% CI 1.422-4.888), and ECC time > 120 min (OR 1.853; 95% CI 1.233-2.783) were all linked to re-exploration (Table 2). Re-exploration was linked in the global series in this analysis of patients undergoing cardiac surgery to obesity, a prior diagnosis of endocarditis, valvular/aortic surgery, and EEC lasting longer than two hours. Nonetheless, homogeneous groups of re-explored and non-re-explored patients chosen by propensity score matching showed no differences in risk variables. Re-exploration was a risk factor for ICU readmission in this comparison, but it did not show up as a predisposing factor for mortality. Prolonged ECC time (> 2 hours) during the initial surgery has been linked in previous studies to the necessity for re-exploration [4,10,11]. Conversely, a low body mass index has been identified as a risk factor [4,10], and obesity has not typically been linked to re-exploration. The high percentage of obese patients—32.2% in the global series and 43.1% in the patients that were reexamined—may have an impact on our findings. Nevertheless, no risk factors were identified to be substantially linked to re-exploration after matching patients who had been examined and those who had not in order to reduce confounding variables. Re-examination was necessary since the patient was unstable and needed vasoactive medications, fluid therapy, and transfusions due to hypotension and hypoperfusion. Tamponade accounted for 56% of the reexploration cases, hemorrhage for 19.8%, and sternal dehiscence for 11.2% of patients. If re-examinations were categorized as early or late, hemorrhage (30.6%) and tamponade (64.5%) were the most common reasons for the former, while tamponade (46.3%), sternal dehiscence (24.1%), and valve-related causes (14.8%) were the most common reasons for the latter. Close patient monitoring and repeated echocardiographic controls are crucial since patients who underwent re-exploration more than 48 hours after surgery had a longer stay in the intensive care unit. However, the death rate did not differ amongst them. The reduced duration of hemodynamic instability (blood loss, tissue hypoxia, vasoactive medications), and subsequently lower level of multiorgan dysfunction, could account for the shorter ICU stay. These findings partially corroborate earlier reports that found longer ICU stays, longer periods of time on mechanical ventilation, and greater fatality rates in patients receiving late re-exploration; however, those investigations characterized this as occurring more than 12 hours after surgery, which could account for the differences observed in our analysis [7, 12].

Table 1: Re-exploration Group characteristics; CABG: Coronary Artery Bypass Graft; MV: Mechanical Ventilation

Table 2: Multivariate analysis of predisposing factors related to Re-exploration.

The vast differences in how other research define “early” and “late” re-exploration make it difficult to compare them with one another. The morbidity and mortality linked to re-exploration in the global series of patients were comparable to those reported in earlier studies, with higher death rates [4,13,14,11], longer periods of mechanical ventilation [4,13,10], higher rates of acute kidney failure [4,13,10,11], and increased dialysis requirements [10]. But there was no correlation found between re-exploration and a higher risk of death among matched groups of patients who had previously explored and those who had not. Re-exploration for bleeding was described by authors as a fatal and morbid side effect of heart surgery [15–16]. The retrospective, single-center design of this investigation presents certain limitations. But because of the large sample size and the use of a propensity score matching technique, the likelihood of election and confounding biases was reduced. In order to produce more comprehensive information, the experimental study’s use of multiple statistical methodologies allowed data to be compared and merged from diverse angles [18].

4. CONCLUSION

Following cardiac surgery, re-exploration is a somewhat common complication that is mostly caused by cardiac tamponade. Re-exploration was not substantially correlated with any risk factor and was not linked to a higher death rate. On the other hand, there was a greater chance of ICU readmission when re-exploration was done.

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