Introduction

Distraction osteogenesis (DO) is an effective therapeutic approach alternative to the use of various bone grafts in the treatment of craniomaxillofacial anomalies and deformities and has become an increasingly popular technique in the past two decades [1]. DO is the traction application to the callus formed between bone fragments created with osteotomies to stimulate bone formation by producing stress on the callus via this traction [2]. Separation and consequent osteogenesis between bone sites are obtained by implanted distraction devices in adjacent bone. After the separation of bone segments and defect repair, activation of the distraction device finishes but the distraction device held in place until the osteoid tissue in the distraction gap has mineralized for consolidation. Due to the time length required for achieving extensive bone regeneration, maturation, and consolidation, distraction osteogenesis process may generate discomfort for patient and may result in some complications [3].

Current aims in the surgical area of DO include enhancing bone regeneration and shortening the necessary time for treatment. Several mechanical, chemical and biological treatment options have been evaluated to increase the quality of newly formed bone and shortening the treatment time of DO [4-8].

Near-infrared (NIR) phototherapy uses monochromatic light in the optical region between 600–1000 nm to irradiate tissues without causing destruction and thermal effects [9]. Phototherapy has been used in medicine and dentistry with the increasing popularity since Maiman developed the ruby laser in 1960. Light-emitting diodes (LEDs) working efficiently of biologically active wavelengths introduced as an alternative photon source after lasers.

Light generated using LED arrays or low-level laser (LLL) between 630–1,000 nm has been shown to enhance retinal function in cultured primary neurons [10]. Phototherapy has the physiologic effect on cellular metabolism with NIR photons absorbed by cytochrome C and increased adenosine triphosphate (ATP) production is achieved in the mitochondria by this respiratory chain which allows improved function and metabolism of poorly perfused or intoxicated cells [11]. Photobiomodulation is suggested to enhance wound healing, tissue regeneration and growth, bone regeneration, nerve regeneration, chondral and fibroblastic proliferation, angiogenesis and collagen synthesis [12-20].

Speeding up the consolidation and bone maturation in DO is a challenging clinical aim. The purpose of this study was to determine the effects of LED photobiomodulation therapy (LPT) on bone healing during the consolidation period of DO and the possibility of a shortened consolidation period for earlier device removal and reduction of complications.

Material and Methods

Sixteen adult male 8-month-old New Zealand rabbits (Oryctolagus cuniculus), each weighing between 3000 and 3500 g divided into two groups (n=8) were used for this study.

The rabbits were kept single in standard cages at a temperature of 23°C, exposed to a 12- hour light-dark sequence. They were acclimated for 2 weeks before surgery. All animals were fed with standard laboratory pellet chow and distilled water ad libitum. The study was approved by Erciyes University Animal Care and Ethics Committee. All procedures and follow-up were held according to local animal studies research center regulations.

Surgical procedure

All surgical processes were done under sterile circumstances in an operating room by the same experienced surgeon. Intramuscular (IM) injection of 35 mg/kg ketamine (Ketalar; Pfizer, New York, USA) and 8 mg/kg xylazine hydrochloride (Rompun; Bayer, Leverkusen, Germany) was used to achieve general anesthesia. The animals were then placed on the operating table in a supine position. The operation area was shaved and prepared with betadine solution. Lidocaine (0.5%) with 1:200.000 epinephrine was injected in the left ramus and submandibular areas subcutaneously. A 3 cm incision was completed through the skin on the left of the mandible 2 cm from the midline. The facial artery was conserved to the extent as much as possible during dissection through the subcutaneous and muscle layers to expose the lateral side of the mandibular corpus. The mental nerve was identified and preserved. A vertical corticotomy between the premolar teeth and inferior border of mandible was made with a reciprocating saw and the titanium pins used for fixating the distractor were placed perpendicular to the corpus and parallel to each other (Figure1). A custom-made distractor was fixed to the pins, then the osteotomy was completed with a thin chisel osteotome and the distractor was tested (Figure 2). Soft tissues were primarily closed in layers.

Postoperatively, both groups of animals were given IM 200.000 U of penicillin and 0.2 mg buprenorphine every 12 hours for 3 days. The wound was cleaned with betadine daily during the first week. After a 5-day latency period, the distractor was activated at a rate of 0.5 mm/12 hours for seven days.

The animals were randomly divided into 2 groups. LPT was applied to the distraction area of 8 rabbits in the experimental group for 21 days starting with the operation. The remaining subjects served as controls.

LED photobiomodulation therapy

OsseoPulse® LED device (Biolux Research Ltd., Vancouver, Canada) was used for LPT application with 618 nm wavelength and 20 mW/cm2 output power in the present study for 20 minutes once a day during21 days after stabilizing animals in a plastic holder to ensure the immobility. The treatment array was positioned in contact with the distraction site (Figure 3). All LPT procedures were applied transmucosally by the same operator (H.A.).

Radiologic and Histomorphometric Analysis

After 30 days of consolidation period, all animals were sacrificed by ketamine and xylazine overdose. Mandibles were dissected out and fixed in 10% formalin (Figure 4).

Dual-energy x-ray absorptiometry (DEXA) analysis was used for radiographic assessment. Bone mineral density (BMD) and bone mineral content (BMC) of bone regenerates in the distraction gap, bone around the pins of distractor and sham group which is normal bone in distracted hemimandibles were measured using DEXA (Lunar DPX-IQ, Madison, WI) (Figure 5).

Each hemimandible was kept in a 10% formalin solution for a week. Then the bone specimens were placed in 10% hydrochloric acid to decalcify for a week at 25˚C. After decalcification, the distraction field was segmented with a scalpel to form a perpendicular slice of mandible. The bone sections were rinsed, trimmed, and implanted in paraffin. The paraffin blocks were sectioned consecutively at 5-μm thickness and stained with hematoxylin and eosin.

All specimens were examined with a light microscope (Nikon Eclipse E400) and a photograph attachment (Nikon Coolpix 5000) was used to photograph each specimen. All images were then transported to PC environment and evaluated with an image analysis program (Clemex Vision Lite Image Analysis 3.5; Clemex Technologies, Longueuil, Canada). Using this analysis program, 0.5 mm2 areas were designated. Excluding damaged cells, vessels, osteoblasts and osteoclasts were marked in the area. With the same image analysis program, the marked cells are automatically calculated. Furthermore, new bone- forming areas were determined and assessed (µm2) in 0.5 mm2 area.

Statistical analysis

All data were analyzed using SPSS (Statistical Package for Social Science, Version 20.0, SPSS Inc., Chicago, IL, USA) package program. The normality and the homogeneity of the data were evaluated using the Kolmogorov-Smirnov normality test and the Levene’s variance homogeneity test. For the osteoclast number and new forming vessel number, the data were not normally distributed thus, the Mann-Whitney U test was used to compare groups. For other variables, the Student t-test was used. The level of statistical significance was set at p less than 0.05.

Results

One animal from the control group was infected and excluded from the study during the consolidation period. A total of 15 hemimandibles which were subjected to DO method were evaluated (p>0.05, Table 1, 2, 3).

When DEXA data were analyzed, it was seen that bone mineral density values were significantly higher in the distraction area of the experimental group (p=0.013, Table 1). However, no significant difference was observed in DEXA data in adjacent bone areas or pin circumferences (p>0.05, Table 1).

Histomorphometric evaluation showed significant increase of osteoblasts and new bone forming area in experimental group (p<0.05, Table 2, Figure 6). In terms of the number of vessels, although the number in the experimental group was higher, it was not statistically significant (p>0.05, Table 3).

Discussion

The use of DO in the treatment of various bone losses and congenital or acquired deformations has become common in maxillofacial surgery in last decades. The main factors affecting the success of the DO are a series of technical factors, such as latency period, distraction rate, rhythm and consolidation length. Long treatment time may lead to various complications during DO [3]. The study reported by Ilizarov stated that a latency phase of at least 7 days is required in adults and could be shorter in pediatric patients. Various studies have suggested different protocols on distraction rates and latency phases [1]. In a study conducted by Aida et al. [21] on the rabbit DO model, it was reported that mature callus with matured lamellar bone is detectable after 4 weeks thus a consolidation period of 1–2 months is appropriate. Currently, a latency period of up to 7 days and a distraction rate of 1 mm per day are considered to be standard in the treatment of adults by DO in clinical practice. Reducing the time of latency and consolidation periods has advantages such as reduced risk of infection and treatment failure. The number of DO researches about shortening the treatment time is increasing. The effects of various pharmacological agents, biostimulation methods, and mechanical stimulation applications to enhance new bone formation during DO were assessed by different researchers.

In the current study, we analyzed the effect of LPT on the quality of osteogenesis during mandibular DO in the rabbits. Although there are studies that investigated the effects of LPT in various surgical procedures, no studies were performed investigating LPT in DO to our knowledge.

Ekizer et al. [14] investigated the efficiency of LED photobiomodulation on bone formation in interpremaxillary suture during orthopedic expansion and showed that it had a stimulating effect on bone formation. El-Bialy et al. suggested that photobiomodulation therapy stimulated mandibular growth in rats [22]. The efficiency of LPT on the rate of orthodontic movement was evaluated by clinical and experimental trials [14,23]. Kau et al. [23] reported that LPT application at 850-nm near-infrared wavelength, increased the rates of orthodontic movement in the alignment phase of treatment clinically. In a human model, more rapid achievement of dental implant stability was demonstrated as a result of the biostimulation effect of LPT [24].

Although there is no study investigating effects of LPT on DO in the literature, there are limited studies about the effect of LLLT. Miloro et al. evaluated the effect of LLLT achieved by 820 nm wavelength GaAlAs laser in the rabbit model and reported that bone formation was higher in LLLT groups than the control groups [15]. Abd-Elaal et al. evaluated the influence of GaAs laser on mandibular DO clinically and reported that bone quality and quantity was higher in the LLLT group than the control group. They offered that LLLT may shorten treatment process [20]. Results of our study in which biostimulation was achieved with an LED source, appear to be similar to LLLT in new bone formation during DO.

The wavelength of irradiation formed by LED is similar to that expended in LLL (600–1,000 nm) and photobiomodulating effects were supplied with both sources. Laser and LED irradiation stimulate the electron transfer in Cytochrome C Oxidase and increase the intracellular ATP production [10]. LPT has been shown to hasten tissue healing and upturn from ischemia due to increased collagen production and angiogenesis by increasing mitochondrial activity and ATP synthesis [25]. Based on these cellular outcomes, LPT may be effective for the increased bone formation in DO. In the current study, LPT was applicated by a LED device with 618nm wavelength and quality of the new forming bone was evaluated during DO.

LED light is not coherent as laser light, then expected to cause less side effects [9]. LED radiation can be created at a lower price in comparison to the LLL, and applicable to a large area of the body surface safely. Other advantages of LEDs over lasers for use in phototherapy include littler hardware package, lower energy density, and reduced eye damage risk. [11]. In addition, the use of LED arrays provides the opportunity to expand the footprint allowing a one-time application for wide surfaces.

In the present study, LPT improved the bone formation significantly according to radiographic and histologic evaluations. BMD values on the 30th day of the consolidation phase were found to vary significantly between the experimental group subjected for LPT in a wavelength of 618 nm and control groups which are in viable with those obtained in similar studies [17,18]. BMD values in the LED group were also consistent with those obtained histopathologically. Photobiomodulation application may provide a clinical advantage by accelerating bone healing during DO as the complications rise according to the treatment time. On account of accelerating bone healing and decreasing treatment time by using LPT, satisfaction and cooperation of the patients can be enhanced.

Conclusions

There are some studies related to effects of photobiomodulation on bone healing in the literature, but there are none with the use of the infrared LED as the light source in DO. In this study, LED photobiomodulation significantly has positive effect on bone healing on newly formed bone in DO according to radiologic and histologic evaluations in a rabbit model. The role of biological and biomechanical variables influencing angiogenesis and mineralization should be determined to improve the best method to hasten bone healing. Further clinical and experimental studies using LED photobiomodulation with bone substitutes should be investigated.

Scientific Responsibility Statement

The authors declare that they are responsible for the article’s scientific content including study design, data collection, analysis and interpretation, writing, some of the main line, or all of the preparation and scientific review of the contents and approval of the final version of the article.

Animal and human rights statement

All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. No animal or human studies were carried out by the authors for this article.

Funding: None

Conflict of interest

None of the authors received any type of financial support that could be considered potential conflict of interest regarding the manuscript or its submission.

References

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Introduction

Empyema is the collection of inflammation in the pleural cavity which has adhesive properties and dense content. If not treated, the mortality rate is more than % 10 [1]. The most common cause is the complication of parapneumonic pleural effusions occurring due to bacterial, viral pneumonia caused by the infective agents.

Shortness of breath, pleuritic chest pain, cough, purulent sputum, fever, chills, and weight loss are the most common symptoms. Diagnostic is made through invasive procedures such as laboratory and radiological examinations, thoracentesis, bronchoscopy or pleural biopsy [2, 3]. The main treatment methods are observation, thoracentesis, tube thoracostomy, fibrinolytic, video-assisted thoracoscopic surgery (VATS), or thoracotomy [4]. The treatment method to be selected depends on many features such as the cause of empyema, being acute or chronic, the degree of infection, the characteristic features of empyema fluids, the state of the underlying lung, bronchopleural fistula existence, and the general condition of the patients [5]. It is known that the pleural drainage performed at the early stages significantly improves the clinical condition. However, some problems might be encountered if the treatment is performed in the late phase [6].

In this study, we aimed to share the characteristics, factors effective in surgery, and treatment outcomes of surgically treated patients with empyema.

Material and Methods

Patients

One hundred fifty-six patients treated with surgical operations within ten years were analyzed retrospectively in the study. All patients provided written informed consent and the study was approved by Dicle University, Medical School Ethical Committee.

Procedures

The files of the patients were analyzed retrospectively. Age, sex, symptoms, co-morbidities, location of disease, diagnostic methods, clinical findings, laboratory tests (pH, lactic dehydrogenase (LDH), glucose) and microbiological (gram stain, culture) results were evaluated.

Surgical methods applied to patients and the results, duration of hospitalization, mortality and morbidity were examined.

Patients were divided into three groups as patients treated with tube thoracostomy, VATS or thoracotomy. The characteristics of each group were investigated. Factors affecting the performance of VATS-thoracotomy instead of tube thoracostomy under local anesthesia, and the application of thoracotomy instead of VATS were investigated.

Inclusion and exclusion criteria

Only the patients treated with surgery were included. Tube thoracostomies applied before VATS or thoracotomy were ignored as no positive results were obtained. The patients applied fibrinolytic and reached positive results were evaluated with tube thoracostomy group.

Statistical analysis

In statistical analysis for continuous variables were expressed as the mean ± standard deviation and categorical variables were explained as number-ratio. The results were analyzed by the Chi-square and Fisher’s exact test. P < 0.05 was considered significant.

Results

The number of patients with pleural effusion treated with surgical procedures in our clinic within ten years was 501, and 156 of those patients (31%) had the diagnosis of empyema. The mean age of the patients was 21.07 ± 17.78 years. 110 (%71) were male, while 46 (%29) were female. All effusions were exudates. The mean pleural fluid was pH: 6:54 ± 0.29, LDH: 863.26 ± 268.21, and glucose: 35.22 ± 5.64. In 26 (17%) patients’ gram stain and culture were positive, whereas in 130 (83%), they were negative. It was discovered that in 60 of the patients (38%), loculations existed and in 40 (26%) fluid having purulent characteristics was aspirated (Table 1).

The complaints were shortness of breath (n = 142, 91%), pleuritic chest pain (n = 135, 87%), cough (n = 87, 56%), purulent sputum (n = 48, 31%), fever (n: 43, 28%), chills (n = 43, 28%) and weight loss (n = 23, 15%). The most common comorbidities were diabetes in 21 (13%) patients, chronic obstructive pulmonary disease in 20 (13%), congestive heart failure in 12 patients (8%), extrapulmonary cancers in 7 (4%), and lung cancer in 5 (3%).

The most frequently used radiological method was chest radiography. Computed tomography was the second most common, and thoracic ultrasonography was the third.

During the treatment, 94 patients (60%) underwent tube thoracostomy (Group 1), 6 (4%) underwent VATS (Group 2) and 56 (36%) underwent thoracotomy (Group 3). The mean age was 19.70 ± 18:53 in Group 1 (n = 94). Sixty-five patients (69%) were male and 29 (31%) were female. Diseases were on the right in 57 (59%) patients, whereas in 37 (41%), it was on the left. The mean pleural fluid was pH: 6.81 ± 0.21, LDH: 663.67 ± 135.09, and glucose: 39.65 ± 5.13. In 5 (5%) patients, gram stain and culture were positive, whereas they were negative in 89 (95%). Loculation existed in 5 patients (5%). In Group 2 (n = 6), the mean age was 14.86 ± 22.33 years. Five patients (83%) were male and 1 (17%) was female. Diseases were on the right in 3 (50%) patients, while they were on the left in 3 (50%). The mean pleural fluid was pH 6.76 ± 0.05, LDH: 590 ± 123.93, and glucose: 40 ± 6:19. Two (33%) patients had positive gram stain and cultures, while 4 (67%) had negative. Loculations were present in 2 patients (33%). In Group 3 (n = 56), the mean age was 25.18 ± 13.66 years. Forty (71%) of the patients were male and 16 (29%) were female. Disease was on the right in 29 (%52), while it was on the left in 27 (48%). The mean pleural fluid was ph: 6,31 ± 0,20, ldh: 1092.14 ± 135.53, and glucose: 31.07 ± 2.66. Gram stain and cultures were positive in 19 (34%) patients, while they were negative in 37 (66%). Loculation existed in 53 (95%) patients. It was discovered that liquid having purulent characteristics was aspirated in 40 (71%) patients by means of thoracentesis.

It was found that gender and localization was not an effective factor in VATS-thoracotomy application. However, gram stain, positive culture results, the presence of loculations and purulent aspiration in thoracentesis were found to have a significant effect on VATS-thoracotomy application (P < 0.05). In addition, when VATS and thoracotomy were compared, the presence of loculations was discovered to have a more significant role in thoracotomy (p < 0.05) (Table 2, 3).

It was seen that 7 (4%) patients died, 7 (4%) postoperative patients had expansion defect and subcutaneous emphysema, 6 (4%) developed incision infection, and 5(3%) had atelectasis. The mean hospitalization time of the patients was 13 ± 2.5 days.

Discussion

Empyema is rare in healthy individuals. Potential risk factors can be listed as diabetes, alcoholism, gastroesophageal reflux disease, substance abuse and neurological diseases [2]. In our study, the most common concomitant diseases were diabetes, chronic obstructive pulmonary disease, congestive heart failure, lung cancer and other cancers.

Diagnosis is made through clinical, laboratory and radiological findings. Clinical signs vary from weakness to toxic diseases, and shortness of breath, chest pain, cough, purulent sputum, and fever are the most common symptoms. In laboratory tests, leukocytosis, sedimentation rate and C-reactive protein (CRP) are found to be high. From empyema fluid, pH, protein, glucose, LDH, adenosine deaminase (ADA) levels, cell count, Gram stain, culture, and cytological examination and acid-fast bacilli should be investigated. Although chest X-rays are adequate for diagnosis tomography, thoracic computed tomography is very important to detect underlying parenchymal lung disease, loculations, to separate lung abscess, and to choose the treatment method [1, 4].

The most common symptoms of our patients were shortness of breath, chest pain, cough, purulent sputum, fever, chills, and weight loss. In addition, the most commonly used diagnostic method was chest x-ray. All patients were examined in terms of pleural fluid pH, glucose, LDH, Gram stain, and culture.

The most common cause of empyema is parapneumonic effusions occurring due to bacterial and/or viral pneumonia being complicated by infective agents [1, 3]. Empyema associated with parapneumonic effusions includes 3 periods. During the exudative period, no bacteria existed in pleural fluid, leukocyte is available, pH and glucose are normal, and LDH is low. Antibiotic is sufficient in treatment. In fibrinopurulent period, bacteria and leukocytes are present in the pleural fluid, and septa and loculations are available in the pleural cavity. In empyema fluids, pH is lower than 7.2, and glucose is lower 40 mg / dl, but LDH is higher than 1000 IU / L. In this period, pleural fluid must be drained. A combination of pouch through VATS and fibrinolytic therapy and irrigation is beneficial. During organizations period, thickening and loculations exist in pleura. Thickened visceral pleura prevent the expansion of the lungs. Narrowing in intercostal space, rise in diaphragm, and reduction in hemithoraces volume can be seen. Empyema is displaced toward the side of the mediastinum. Complications such as lung abscesses, bronchopleural fistula, empyema necessitates, rib-spine osteomyelitis, mediastinitis, pericarditis and brain abscess can develop. Decortication should be performed during this period [6, 7]. Ten percent of the parapneumonic effusions turn into empyema asa complication [8]. Pleural effusions are classified into 4 categories according to anatomical, bacteriological, and chemical properties of the fluid [3]. In category 1, pleural effusion, whose pH and culture-gram stain results are not clear and which has less than 10mm level in lateral decubitus graffiti exists. Drainage is not required. In category 2, pleural effusion, whose gram stain and culture results are negative, pH ≥ 7.20, and level is greater than 10mm, but less than half of a hemithorax in lateral decubitus graphite. Drainage is not required. In category 3, loculated effusion at least half of a hemithorax, pleural thickening, positive culture-gram stain are present and pH values are <7.20. Drainage is required. In this group, the risk of complications is moderate. In category 4, fluid at least half of a hemithorax exists. From the expansion defect and purulent fluid, one of the conditions is adequate. Drainage is required. The risk of complications is higher in this group. In this study, the mean pleural fluid for all patients is as follows: pH: 6:54 ± 0.29, LDH: 863.26 ± 268.21, and glucose: 35.22 ± 5.64. In twenty-six of the patients, gram stain and culture results were positive, loculations existed in sixty patients and purulent fluid was observed in 40 patients. In Group 1, the mean pleural fluid was as follows: pH: 6.81 ± 0.21, LDH: 663.67 ± 135.09, and glucose: 39.65 ± 5.13. Five patients had positive gram stain and cultures, and loculation was present in 5 patients. In Group 2, the mean pleural fluid was pH: 6.76 ± 0.05, LDH: 590 ± 123.93, and glucose: 40 ± 6:19. Two patients had positive gram stain and cultures, and loculations existed in 2 patients. In Group 3, the mean pleural fluid was as follows: pH: 6.31 ± 0.20, LDH: 1092.14 ± 135.53, and glucose: 31.07 ± 2.66. Nineteen patients had positive gram stain or culture, in 53 patients loculations were present, and in 40 patients, purulent fluid aspiration existed.

Basic strategies of empyema treatment are controlling infection and sepsis with appropriate antibiotics, drainage of purulent fluid, correction of empyema cavity, prevention of resistant or recurrent disease and the expansion of the lung tissue. Observation, thoracentesis, tube thoracostomy, fibrinolytics, the removal of adhesions with VATS or thoracotomy, decortication and open drainage are the main treatment methods [4]. The treatment method to be selected depend on the cause of empyema, being acute and chronic, the degree of infection, the properties of empyema fluid, underlying condition of the lung, the radiological findings, the presence of bronchopleural fistulas, being able to close the empyema cavity and the general condition of the patients [5].

Although tube thoracostomy plays an important role in the treatment of empyema, simple tube drainage is not sufficient in 36-65% of patients [1, 9]. Chest tube should be installed in areas where there is a large effusion. This can be done successfully with ultrasound or computerized tomography [10]. After tube thoracostomy, clinical and radiological improvement is achieved in 24 hours. If improvement is not seen, it probably means that pleural drainage may not be adequate. The main reasons for the lack of sufficient drainage are the location of the chest tube in the wrong place, the presence of loculations and visceral pleura confining the lungs. In this case, fibrinolytic therapy with the chest tube should be considered. It may be useful in dense fluids which have multiple loculations and viscosity. Fibrinolitics, eliminating septa, facilitate drainage by combining loculations (chemical decortication). Streptokinase, urokinase, and tissue plasminogen activator are the main fibrinolytics used. Complications such as anaphylaxis, pulmonary edema and hemorrhage may develop. In a study conducted, the routine use of intrapleural fibrinolytic therapy was not recommended due to complications .VATS is a safe and effective method in the case of the presence of multiple loculations which are resistant to fibrinolytic therapy or in which tube drainage with thoracotomy cannot be achieved fully [11, 12].

Video-assisted thoracoscopic surgery yields good clinical results in early interventions such as fibrinopurulent period. Therefore, it is recommended to be applied in 4 weeks [4, 13]. The success rate of VATS in empyema treatment is reported to be 68-93% [14, 15]. VATS also provides an opportunity for taking samples from pleural fluid and pleura. Loculations are combined by opening fibrotic septa and bands in the pleural cavity. Pleural drainage is fully provided. By performing debridement and irrigation, chest tube can be placed into the most suitable localization. Additionally, with the help of this method, pleural plaques which are thickened and prevent lung expansion can be identified, and decortication can immediately be performed. The rate of progression to thoracotomy and open surgical decortication during VATS is between 3.1-40% [16]. Stefani et al. [5] reported that delayed operations, fever and pleural thickening are decisive factors for VATS cases which are progressed to thoracotomy due to the complete decortication need. VATS is a less invasive treatment method which is as effective as thoracotomy-decortication in the treatment of empyema. In the literature, it has been reported that early surgical debridement results of the patients over 80 years old treated with VATS are excellent, thus advanced age does not create a contraindication to surgery [17]. Decortication is a major application requiring thoracotomy incision. In addition, it must be suitable for the general condition of patients. Decortication is the extraction of fibrous tissue in visceral and parietal pleura, cleaning purulent fluid and debris and ensuring the expansion of the underlying lung. Decortication to thickened pleura should not be performed in the acute phase as the thickening will disappear in a few months. Decortication can be performed in cases where acute period is over in 3-6 months but pleura are still thick and lung functions decrease [18]. By being patient to decortication, parenchymal damage and postoperative air leak should be reduced to a minimum. With swelling of the lungs, pleural space should be filled, and reaccumulation of fluid should be prevented. During the decortication process, mortality is observed between 1.3-6.6% [19, 20]. Despite this mortality rate, decortication process should be applied to suitable indicated patients [21]. In our study, the mortality rate was 4%. Muhammad et al. [6] stated that they have 50% success through intrapleural streptokinase therapy, 92% with VATS, and 100% with decortication in the treatment of complicated parapneumonic effusion and empyema. In this study, 94 of patients were treated with tube thoracostomy, 6 underwent VATS, and 56 were treated through thoracotomy. When the factors for the selection of the treatment method were considered, it was discovered that gender and localization are not effective in performing tube thoracostomy or VATS-thoracotomy, but the positive Gram stain or culture results, the presence of loculations and purulent aspiration in thoracentesis are significantly effective in VATS-thoracotomy application (p < 0.05). Additionally, when VATS and thoracotomy were compared, the presence of loculations was found to be more effective in performing thoracotomy (p < 0.05).

Open drainage methods are preferred in patients in whom VATS or thoracotomy cannot be performed. There are 2 types of chronic pleural drainage. In Clagett method, which is simple and safe, 1-3 ribs located in the lower part of the empyema cavity are partially resected, a short-thick chest tube is inserted into the empyema cavity and connected to the drain bag. Detoxification is provided by irrigating empyema cavity with antibiotic solutions from the drain. The other method is Eloess, which is more complicated. In this method, a tract is created by using skin-muscle flaps between chest wall and empyema cavity. In the method, 2 or more ribs located in area suitable for empyema cavity are partially resected. Additionally, fistula is formed, and there is no need to use the tube. This application is better tolerated and permits the closure of empyema cavity. In both methods, pleural adhesions are required to not to create a pneumothorax, and they are usually performed at the late period [22]. Recently, mini-vac treatment has been performed to the empyema patients who have a poor general condition and multimorbidity. With this treatment, positive results such as decrease in empyema cavity, acceleration of lung expansion, and early improvement in empyema [23, 24]. In our study, open drainage methods were not performed.

Consequently, tube thoracostomy is the most commonly used surgical method in empyema treatment. Despite the risk of increased mortality, VATS and thoracotomy should be implemented in cases where tube thoracostomy is not successful. Additionally, VATS and thoracotomy should be preferred in cases where gram stain and culture results are positive, and loculations and purulent aspiration exist.

Scientific Responsibility Statement

The authors declare that they are responsible for the article’s scientific content including study design, data collection, analysis and interpretation, writing, some of the main line, or all of the preparation and scientific review of the contents and approval of the final version of the article.

Animal and human rights statement

All procedures performed in this study were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. No animal or human studies were carried out by the authors for this article.

Funding: None

Conflict of interest

None of the authors received any type of financial support that could be considered potential conflict of interest regarding the manuscript or its submission.

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