Patients and methods: A prospective analysis of 129 patients (100 males, 29 females; mean age: 62.9±8.5 range, 44 to 82) who underwent routine off-pump isolated coronary artery bypass grafting surgery between January 2018 and December 2018 was performed. The number of patients who had subxiphoid mediastinal drainage and one mediastinal Jackson-Pratt drainage was 64 (Group 1), and the number of patients who had subxiphoid mediastinal drainage and intercostal chest drainage was 65 (Group 2). Postoperative pain scores, analgesic needs of patients, and radiological effusion and pneumothorax assessments were recorded, and pleural complications requiring invasive intervention were compared.

Results: There was no difference between the groups in terms of age, sex, and comorbidities. There was a significant superiority in Group 2 in terms of pain scoring in the first hour after extubation and the need for analgesia in all follow-up periods (p<0.001). In two (3.12%) patients in Group 1 and in two (3.07%) patients in Group 2, pleural effusion requiring intervention was detected. There was no significant difference between the two groups in terms of effusion pneumothorax, in terms of blood transfusion, and other postoperative complications. Postoperative whole blood replacement was higher in Group 2 (p=0.002).

Conclusion: In off-pump heart surgery patient groups that do not have a high risk of bleeding, follow-up can be done without inserting an intercostal chest tube as a result of good bleeding control.

Due to their structure, the use of smaller and more flexible silicone drains can be as effective as larger and firm drains.[6] These drains are clog-resistant and cause less patient discomfort with their small size and flexibility. In addition, an earlier study showed that the incidence of pericardial effusion, tamponade, and postoperative atrial fibrillation was reduced compared to conventional large drains.[7] This study aimed to evaluate whether postoperative pain level changes and whether complications such as effusion and pneumothorax that require intervention arise due to the drainage placed in the thorax cavity, either intercostal or subxiphoidal.

Anesthesia and surgical technique
Standardized drugs (midazolam, rocuronium, fentanyl, and propofol) were administered to all patients as anesthetic drugs by the same anesthesia team at our institution. All patients were operated on by median sternotomy. The internal mammary artery was used in all patients. The saphenous vein was used for other vessels according to the number of diseased vessels. Off-pump surgery was performed in all patients. After appropriate heparinization (heparin at a dose of 1 mg/kg; activated clotting time was kept at >300 sec), distal anastomoses were performed with octopus support, and proximal anastomoses were performed with a side clamp. After standard bleeding controls, one no. 32 Fr drain and one Jackson-Pratt drain (extending between the posterior part of the heart and the pericardium) were placed to the mediastinum of patients in Group 1. No thorax drain was placed in this group of patients. In Group 2, one no. 32 Fr drain was placed in the mediastinum and one no. 36 Fr drain in the left thorax (through the fifth or sixth intercostal space in the middle axillary region). Heparin neutralization was performed with protamine. The mediastinum was routinely closed in all of the patients in the same way.

Postoperative follow-up
All patients were transferred to the intensive care unit. Pneumothorax was checked by posteroanterior chest radiographs. All patients were extubated at the appropriate time after routine intensive care follow-up. The pain assessment of the patients in the surgical area was started 1 h after the extubation and evaluated every 6 h using a verbal pain category scale indicated in Figure 1, and the scores were recorded.[8] Nonsteroidal pain relievers were administered to patients who responded as feeling a pain level of 2 or 3. Narcotic analgesics (tramadol 50 mg) were administered to patients who indicated a pain level of 4 or 5.

Figure 1. Verbal category scale.[8]

Intensive care follow-up was performed to the same standards. Antiaggregant and anticoagulant postoperative treatment was conducted similarly. Drains were pulled in the last 12 h if there was less than 100 mL of drainage. The first posteroanterior chest radiographs were obtained after the operation. Chest radiographs were renewed daily until discharge. After the patients were discharged, chest radiographs were taken on the seven- and 30-day controls to see if there was any effusion requiring intervention in the left thorax. Posteroanterior chest radiographs were obtained at discharge, and both posteroanterior and left lateral radiographs were taken in controls after discharge since they were able to show less amount of fluid. Thorax ultrasonography was performed on patients with suspicious appearance on direct radiographs as it is more sensitive. Consultations from the thoracic surgery department were conducted for the patients with effusion findings to discuss whether to intervene. In case of need, pleural drainage procedures were performed by the same surgical team.

Statistical analysis
Statistical analysis was performed using IBM SPSS version 23.0 software (IBM Corp., Armonk, NY, USA). Data were reported as mean ± standard deviation (SD), median (interquartile range), or frequency (percentage). The independent sample t-test, chi-square test, Fisher exact test, Mann-Whitney U test, GLM, and repeated analysis of variance measurements were used. The statistical significance level was accepted as p<0.05.

Table 1 Preoperative demographic characteristics and clinical data

Preoperative laboratory data were compared between the groups. The albumin value was significantly higher in Group 1, and the calcium value was significantly higher in Group 2. There was no significant difference in other baseline values (Table 2).

Table 2 Preoperative laboratory values

Effusion requiring drainage was detected in two patients at the first control after discharge in Group 1. In the same group, one patient had minimal pneumothorax without intervention in the left thorax. In Group 2, two patients underwent percutaneous thoracentesis due to significant pleural effusion at the first outpatient control, although there were no patients with pneumothorax. Frequency of these complications was not statistically significant between the two groups.

Although there were no significant differences in the amount of postoperative drainage and intraoperative and postoperative blood transfusion, the need for fresh frozen plasma and fresh whole blood in the postoperative period was significantly higher in Group 2 (Table 3). Operation time, postoperative extubation time, postoperative atrial fibrillation frequency, and discharge times were similar in both groups. The number of vessels undergoing anatomic surgery and the length of intensive care unit stay were significantly higher in Group 1 (Table 4). The verbal category scale for the pain assessment of the patients was found to be significantly higher in those in Group 2 in all evaluation periods in the first 48 h (Table 5). Based on the pain rating scale, nonsteroidal analgesia and narcotic analgesia applications were significantly higher in Group 2 (Table 6).

Table 3 Blood transfusion and drainage between groups

Table 4 Operational and postoperative follow-up parameters between groups

Table 5 Comparison of pain scores between groups

Table 6 Postoperative pain relief between the groups

In a study conducted by Guden et al.[11] in 2012, it was shown that both the subxiphoid and intercostal tract could be used to insert a chest tube. Although there are early studies on different locations of the chest tube, no studies have been conducted on not placing drains into the thoracic cavity. Pericardial tamponade is the most feared complication after cardiac surgery. We were able to execute the study since we used mediastinal drains to eliminate this risk.

In a study by Frankel et al.,[12] no significant difference was evident in intensive care follow-ups between the patients who were using classical chest tubes and flexible silastic drains. In our study, although there was a significant difference in terms of length of stay in the intensive care unit in favor of the patients in Group 1, it did not affect our results since it was not one of the main evaluation points of this study.

There was a significant difference in pain scores and analgesia needs, particularly in the postoperative follow-up period and until the drains were removed. There was a significant decrease in pain in Group 1 starting at the first hour after the intubation and in the type and amount of analgesia performed. In a study conducted by Bjessmo et al.,[13] no significant difference was reported in the assessment of pain with the use of two different drains. There are contradictory results in the literature on this subject. Some studies support the results of our study.[14,15] Although there was a significant increase in the duration of intensive care unit stay in Group 1, significant improvements were observed in patients in Group 2 in terms of treatment compliance, mobilization, and compliance with respiratory physiotherapy exercises. These data suggest that this is due to low levels of pain and analgesic needs of patients. Pulmonary hypoventilation findings may occur due to decreased pulmonary function of patients due to trauma in bone and muscle during surgery.[16] The location of the drain to be placed in the thoracic cavity has been well studied, and in our study, effusion, which required thoracentesis on the fifth postoperative day, was detected only in two patients after the drainage was not placed in the thorax cavity. Only one patient developed left minimal pneumothorax that did not require any intervention and regressed in the follow-up. In the same way, the necessity of thoracentesis was determined and applied to the two patients in the first group after discharge. This suggests that there is no significant difference in pleural complications. Our results are not congruent with a priori knowledge of the necessity of a thoracic tube in classical surgical teaching.

Pleural effusion after cardiac surgery may be due to many causes.[17] However, it is mainly caused by leaks due to trauma in the inner wall of the thoracic wall triggered by the removal of the internal mammary artery. Our study does not focus on the causes of effusion but on whether there is a difference between drain types and accumulated fluid. It is suggested that the absence of a significant hemothorax is due to the fact that there is no adverse effect on the coagulation system in patients due to off-pump surgery and good bleeding control within the operation.

In a study conducted in 2002, no significant difference was reported between flexible silastic drains and classical large drains in terms of pericardial tamponade and pleural effusion.[15] In another study by Moss et al.,[18] similar effusion tamponade results were obtained for both drainage methods. In our study, there was no significant difference in terms of pleural effusion and pericardial tamponade despite the absence of thorax drainage.

One of the common problems after open heart surgery is cardiac arrhythmias with predominantly atrial fibrillation.[19] In the first three days after surgery, there is a significant increase in atrial fibrillation formation.[20] Some studies indicated that the development of atrial fibrillation leaded to a prolonged postoperative intensive care follow-up and discharge times.[21,22] In our study, although the development of atrial fibrillation was higher in percentage, particularly in Group 2, there was no difference between the groups. Since other factors that play a role in the development of atrial fibrillation were not fully compared in our study, it is difficult to make a conclusive comment based only on the types of drains. The fact that there was no significant difference between the two groups in terms of operation times, postoperative intubation times, postoperative stroke, and discharge times made it easier for us to compare postoperative pain and pleural complications.

In Group 2, higher activated prothrombin time and international normalized ratio values in the preoperative period caused an increase in intraoperative fresh frozen plasma and postoperative fresh whole blood transfusion. This situation is incongruent with the studies reported in the literature. Since other parameters were not studied in terms of bleeding, no definitive interpretation could be remarked regarding this condition.

There were several limitations in the present study. The first limitation was the detection of the amount of postoperative effusion by chest radiography, which is known for being not sensitive to effusions of less than 200 mL. This evaluation was first performed by the cardiac surgery team and not by the radiology team. The second limitation was that the follow-up of the patients was not completely blinded, as the same team conducted the follow-ups. The effect of other sources of pain, such as median sternotomy and saphenous incision location, could not be included in the study. In our clinic, a 36 Fr tube was used for the thorax region as a routine procedure. The size and type of chest tubes (36 Fr tube) may have affected the effectiveness of pleural drainage, pain sensation, and associated morbidities.

In conclusion, drains are crucial for patient monitoring in cardiac surgery. We believe that, particularly in off-pump heart surgery patients who do not have a high risk of bleeding, follow-up can be done without inserting an intercostal chest tube if good bleeding control is provided. More comprehensive studies are needed on this subject.

Ethics Committee Approval: The study protocol was approved by the Abant İzzet Baysal University Clinical Researches Ethics Committee (date: 28.12.2017, no: 2017/201). The study was conducted in accordance with the principles of the Declaration of Helsinki.

Patient Consent for Publication: A written informed consent was obtained from each patient.

Data Sharing Statement: The data that support the findings of this study are available from the corresponding author upon reasonable request.

Author Contributions: Idea/concept, design, data collection and/or processing, writing the article: F.B.; Analysis and/or interpretation: K.T.; Control/supervision, analysis and/or interpretation, literature review, critical review: Y.V.

Conflict of Interest: The authors declared no conflicts of interest with respect to the authorship and/or publication of this article.

Funding: The authors received no financial support for the research and/or authorship of this article.

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