pneumonectomy is a lung resection technique that has been used to remove all lung lobes in humans and dogs when bilobectomy or lobectomy techniques are inadequate to remove the pathology in the hemi - thorax . in dogs
, pneumonectomy has been performed in some pathological conditions , such as lung tumors , congenital lung anomalies , chronic lung collapse , chronic progressive lung inflammation , post - traumatic diffuse parenchymal laceration , and bronchial rupture .
the reported morbidity and mortality rate after pneumonectomy is extremely high in humans suffering from respiratory , cardiac and gastrointestinal system problems , acute respiratory distress , pneumonia , pulmonary edema , pulmonary thromboembolism , bronchopleural fistula ( bpf ) , pyothorax , esophagopleural fistula , cardiac herniation , lung lobe torsion , hemathorax and chylothorax .
the most commonly encountered complication of pneumonectomy in humans is bpf , which is described as a pathologic connection between the bronchus and pleural space [ 2,3,18,19,21,31 - 33,36 ] .
closure failure of the bronchial stump ( bs ) after partial or complete lung resection is the primary cause of bpf in humans , leading to a prolonged hospitalization period and the need for multiple operations [ 1,11,16 - 18,19,21,31 - 34,36 ] .
some authors   have reported of the incidence of bpf to be in the range of 0 - 28% , while others   have reported the incidence to be between 0% and 12% .
the mortality rate of bpf has been reported to be between 15% and 70% [ 8,10,14,16,18 - 20,37 ] .
pneumonia , pleural infections and failure in bs closure are the primary risk factors for bpf . the proper bs closure technique to prevent bs dehiscence after pneumonectomy has been long debated in the field of human thoracic surgery .
therefore , the stapler technique has been used to prevent bpf in humans and dogs [ 1 - 3,17,22 ] .
there seems to be no consensus between researchers regarding the optimal method for bs closure because several authors have made different suggestions for this procedure .
the surgical procedures for bs closure are focused on suture line ( transversal versus longitudinal ) , suture technique ( manual versus mechanical ) , clamping technique ( open stump technique versus closed stump technique ) and whether or not to wrap the bs ( e.g. pleuralization , flap ) . both manual ( by running or interrupted suture ) and mechanical sutures have been routinely used in humans and dogs .
the superiority of both methods has been clearly demonstrated by incidence of bpf complications in humans . in recent years , the autogenic tissue wrapping of the bs after pneumonectomy has been reported to decrease the incidence of bpf .
therefore , in this technique the intercostal muscle flaps are primarily used to support the vascularity of the bs and the line of anastomosis in the trachea .
in addition , the popularity of intercostal muscle flap usage has been increased in human thoracic surgery due to their thickness , autogenous and self - vascularization properties . in the present study ,
this literature data was compared with the histologic healing and bpf complications encountered following three different bs closure techniques ( manual suture , stapler and manual suture plus tissue flab ) after pneumonectomy in dogs were evaluated for a period of one month .
a total of 27 hybrid dogs ( two years old , 20 kg in weight and sex was not considered ) were used in this study .
histological healing was evaluated in 18 dogs ( n = 18 ) ; nine dogs ( n = 9 ) were reviewed separately due to postoperative complications .
the 18 dogs were separated into two groups : group i ( gi ) ( n = 9 ) and group ii ( gii ) ( n = 9 ) .
right and left pneumonectomies were performed in the dogs in gi and gii , respectively .
the dogs in gi and gii were further divided into three subgroups [ subgroup i ( sgi ) ( n = 3 ) , subgroup ii ( sgii ) ( n = 3 ) and subgroup iii ( sgiii ) ( n = 3 ) ] according to the bs closure technique performed . the main stem bronchus was closed with a manual suture in subgroup i ( sgi ) ( n = 3 ) , with a stapler in subgroup ii ( sgii ) ( n = 3 ) , and with a manual suture plus tissue flab ( pedicled intercostal externus - internus muscle ) in subgroup iii ( sgiii ) ( n = 3 ) following pneumonectomy ( table 1 ) .
the dogs were anesthetized and continued with 2% isofloran after the administration of xylasine hcl ( 1 mg / kg i m ) and thiopental na ( 15 mg / kg iv ) .
respiration was ensured by mechanical ventilation ( 15 ml / kg tidal volume , respiration rate 15/min and 25 cm h2o alveolar pressure ) .
thoracotomy incision was made on the 4th intercostal space according to the standard procedure in the sgi and sgii groups , but the 4th intercostal externus - internus muscle prepared as a pedicled flap in the sgiii group .
pneumonectomy was carried out using the open bronchi resection technique in groups sgi and sgiii . in sgii , however , resection was performed after stapler closure .
subgroup i ( manual suture ) : vertical mattress sutures were applied over the excision line , and the end of the stump was sutured with a simple interrupted suture pattern using 2 - 0 vicryl ( ethicon , uk ) ( fig .
subgroup ii ( stapler ) : a ta-30 stapler ( ethicon , uk ) ( 4.8 mm ) was initially applied to the main stem bronchus , and the bronchus was then excised ( fig .
subgroup iii ( manual suture plus tissue flab ) : pedicled intercostal externus - internus muscle was extended towards the bs and then wrapped and sutured using a simple continuous suture pattern with 2 - 0 vicryl after manual suturing of the bs with 2 - 0 vicryl ( fig .
the pleural space was filled with warm sterile saline , and then 50 cm h2o endobronchial pressure was applied to determine the bronchial air leakage .
extra vertical mattress suture(s ) was / were applied over the excision side of the bs in cases where air bubbles occurred due to the bs .
saline was aspirated , and a 28-french thoracostomy tube ( argyle , usa ) was inserted into the pleural cavity ventro - cranially .
the tube was fixed to the skin with a ' chinese finger trap ' suture pattern , and a heimlich flutter valve was connected to the tube for pleural drainage .
postoperative care was carried out in compliance with the rules of the national society of medical research principles of laboratory animal care for a period of one month .
the dogs were relieved with carprofen ( 5 mg / kg / d sc ) .
cefazolin na ( 20 mg / kg iv tid ) was used as an antibiotic agent for 5 days .
hematologic parameters and blood gas analysis of the dogs were controlled routinely , and the dogs were closely monitored for suspected cardiac problems and respiratory failure after pneumonectomy .
the thoracostomy tube and skin sutures were removed on days 5 and 7 after surgery , respectively . at the end of the postoperative first month
, the dogs in gi and gii were sacrificed with high - dose thiopental na .
the bs was removed from each animal , fixed in 10% neutral - buffered formalin and then embedded in paraffin .
five micrometer thick sections from these samples were placed on slides and stained with hematoxylin and eosin for microscopic examination .
statistical analysis was carried out using fisher 's exact test and pearson 's chi - square test to determine the differences between subgroups in terms of histological healing and bpf complications , respectively .
a total of 27 hybrid dogs ( two years old , 20 kg in weight and sex was not considered ) were used in this study .
histological healing was evaluated in 18 dogs ( n = 18 ) ; nine dogs ( n = 9 ) were reviewed separately due to postoperative complications .
the 18 dogs were separated into two groups : group i ( gi ) ( n = 9 ) and group ii ( gii ) ( n = 9 ) .
right and left pneumonectomies were performed in the dogs in gi and gii , respectively .
the dogs in gi and gii were further divided into three subgroups [ subgroup i ( sgi ) ( n = 3 ) , subgroup ii ( sgii ) ( n = 3 ) and subgroup iii ( sgiii ) ( n = 3 ) ] according to the bs closure technique performed . the main stem bronchus was closed with a manual suture in subgroup i ( sgi ) ( n = 3 ) , with a stapler in subgroup ii ( sgii ) ( n = 3 ) , and with a manual suture plus tissue flab ( pedicled intercostal externus - internus muscle ) in subgroup iii ( sgiii ) ( n = 3 ) following pneumonectomy ( table 1 ) .
the dogs were anesthetized and continued with 2% isofloran after the administration of xylasine hcl ( 1 mg / kg i m ) and thiopental na ( 15 mg / kg iv ) .
respiration was ensured by mechanical ventilation ( 15 ml / kg tidal volume , respiration rate 15/min and 25 cm h2o alveolar pressure ) .
thoracotomy incision was made on the 4th intercostal space according to the standard procedure in the sgi and sgii groups , but the 4th intercostal externus - internus muscle prepared as a pedicled flap in the sgiii group .
pneumonectomy was carried out using the open bronchi resection technique in groups sgi and sgiii . in sgii , however , resection was performed after stapler closure .
subgroup i ( manual suture ) : vertical mattress sutures were applied over the excision line , and the end of the stump was sutured with a simple interrupted suture pattern using 2 - 0 vicryl ( ethicon , uk ) ( fig .
subgroup ii ( stapler ) : a ta-30 stapler ( ethicon , uk ) ( 4.8 mm ) was initially applied to the main stem bronchus , and the bronchus was then excised ( fig .
subgroup iii ( manual suture plus tissue flab ) : pedicled intercostal externus - internus muscle was extended towards the bs and then wrapped and sutured using a simple continuous suture pattern with 2 - 0 vicryl after manual suturing of the bs with 2 - 0 vicryl ( fig .
the pleural space was filled with warm sterile saline , and then 50 cm h2o endobronchial pressure was applied to determine the bronchial air leakage .
extra vertical mattress suture(s ) was / were applied over the excision side of the bs in cases where air bubbles occurred due to the bs .
saline was aspirated , and a 28-french thoracostomy tube ( argyle , usa ) was inserted into the pleural cavity ventro - cranially .
the tube was fixed to the skin with a ' chinese finger trap ' suture pattern , and a heimlich flutter valve was connected to the tube for pleural drainage .
postoperative care was carried out in compliance with the rules of the national society of medical research principles of laboratory animal care for a period of one month .
the dogs were relieved with carprofen ( 5 mg / kg / d sc ) .
cefazolin na ( 20 mg / kg iv tid ) was used as an antibiotic agent for 5 days . lactate ringer and
hematologic parameters and blood gas analysis of the dogs were controlled routinely , and the dogs were closely monitored for suspected cardiac problems and respiratory failure after pneumonectomy .
the thoracostomy tube and skin sutures were removed on days 5 and 7 after surgery , respectively . at the end of the postoperative first month , the dogs in gi and gii were sacrificed with high - dose thiopental na .
the bs was removed from each animal , fixed in 10% neutral - buffered formalin and then embedded in paraffin .
five micrometer thick sections from these samples were placed on slides and stained with hematoxylin and eosin for microscopic examination .
statistical analysis was carried out using fisher 's exact test and pearson 's chi - square test to determine the differences between subgroups in terms of histological healing and bpf complications , respectively .
postoperative ventrodorsal and lateral radiographs showed no signs of intra - thoracic pathology , such as pneumothorax or hemathorax , in the dogs during a one - month period following pneumonectomy .
2a ) ; however , no abnormal clinical condition due to mediastinal shift was observed .
complications were encountered in 9 of the 27 dogs ( 10 dogs in sgi , 7 dogs in sgii and 10 dogs in sgiii ) and included two bpfs ( on the 5th and 10th day ) , one postoperative cardiac failure ( 15th day ) and one postoperative respiratory arrest ( 1st h after surgery ) in the sgi group ; one bpf ( 5th day ) in the sgii group ; and two bpfs ( on the 1st week and 15th day ) , one cardio - pulmonary failure ( on 3rd week ) and one peri - operative cardiac arrest in the sgiii group ( table 2 ) . respiratory arrest and sudden onset of death
tension pneumothorax and subcutaneous emphysema were observed in the postmortem radiographs of these animals ( fig .
necropsy on the dog that died on the 15th day revealed myocardial petechial hemorrhagic spots related to the cardiac failure . in a different dog in sgi ,
the cause of the postoperative respiratory arrest ( 1 h after surgery ) was insufficient lung volume , which caused the postoperative spo2 value of the dog to decrease .
in sgiii , alveolar emphysema , pneumonia and petechial myocardial hemorrhage were seen macroscopically in the dog with cardiopulmonary failure that died during the 3rd week after surgery .
peri - operative cardiac arrest after left pneumonectomy was seen as a complication in one of the dogs in sgiii .
this was related to an underlying cardiac problem , which was determined to be an atrioventricular blockage and sinus pause after pneumonectomy based on the results of ecg .
subgroup i ( manual suture ) : histological examinations revealed complete healing in 4 out of 6 bronchial stumps
. granulation tissue formation with new vessel formations as well as continued phagocytosis of the suture material was seen around these 4 bronchial stumps ( fig .
one had severe neutrophil infiltration , and the other had severe neutrophil infiltration along with purulent bronchitis .
subgroup ii ( stapler ) : in the histological examination , complete healing was seen in 4 of these 6 bronchial stumps .
new granulation tissues were seen around the bs and stapler particles were surrounded by macrophages and were being phagocytosed ( fig .
the other two samples had diffuse and severe hemorrhages in the regeneration area , and their healing was considered to be incomplete .
subgroup iii ( manual suture plus tissue flab ) : complete healing was observed in 3 out of 6 bronchial stumps .
the muscle flap used for bs closure was degenerated and necrotized to a great extent , and a granulation tissue forming around the bs covered the area ( fig .
in 2 of the 3 incomplete bronchial stumps , severe neutrophil infiltrations and severe hemorrhage were observed .
the numbers of complete and incomplete histological healings and bpf complications within the subgroups are presented in table 3 .
there were no statistically significant differences in histological healing between the sgi and sgiii groups ( p = 1.00 ; p > 0.05 ) , nor between the sgii and sgiii groups ( p = 1.00 ; p > 0.05 ) .
similarly , there were no significant differences in bpf complications between the sgi , sgii and sgiii groups ( p = 0.945 ; p > 0.05 ) .
postoperative ventrodorsal and lateral radiographs showed no signs of intra - thoracic pathology , such as pneumothorax or hemathorax , in the dogs during a one - month period following pneumonectomy .
2a ) ; however , no abnormal clinical condition due to mediastinal shift was observed .
complications were encountered in 9 of the 27 dogs ( 10 dogs in sgi , 7 dogs in sgii and 10 dogs in sgiii ) and included two bpfs ( on the 5th and 10th day ) , one postoperative cardiac failure ( 15th day ) and one postoperative respiratory arrest ( 1st h after surgery ) in the sgi group ; one bpf ( 5th day ) in the sgii group ; and two bpfs ( on the 1st week and 15th day ) , one cardio - pulmonary failure ( on 3rd week ) and one peri - operative cardiac arrest in the sgiii group ( table 2 ) . respiratory arrest and sudden onset of death
tension pneumothorax and subcutaneous emphysema were observed in the postmortem radiographs of these animals ( fig .
necropsy on the dog that died on the 15th day revealed myocardial petechial hemorrhagic spots related to the cardiac failure . in a different dog in sgi ,
the cause of the postoperative respiratory arrest ( 1 h after surgery ) was insufficient lung volume , which caused the postoperative spo2 value of the dog to decrease .
in sgiii , alveolar emphysema , pneumonia and petechial myocardial hemorrhage were seen macroscopically in the dog with cardiopulmonary failure that died during the 3rd week after surgery .
peri - operative cardiac arrest after left pneumonectomy was seen as a complication in one of the dogs in sgiii .
this was related to an underlying cardiac problem , which was determined to be an atrioventricular blockage and sinus pause after pneumonectomy based on the results of ecg .
subgroup i ( manual suture ) : histological examinations revealed complete healing in 4 out of 6 bronchial stumps .
granulation tissue formation with new vessel formations as well as continued phagocytosis of the suture material was seen around these 4 bronchial stumps ( fig .
one had severe neutrophil infiltration , and the other had severe neutrophil infiltration along with purulent bronchitis .
subgroup ii ( stapler ) : in the histological examination , complete healing was seen in 4 of these 6 bronchial stumps .
new granulation tissues were seen around the bs and stapler particles were surrounded by macrophages and were being phagocytosed ( fig .
the other two samples had diffuse and severe hemorrhages in the regeneration area , and their healing was considered to be incomplete .
subgroup iii ( manual suture plus tissue flab ) : complete healing was observed in 3 out of 6 bronchial stumps .
the muscle flap used for bs closure was degenerated and necrotized to a great extent , and a granulation tissue forming around the bs covered the area ( fig .
in 2 of the 3 incomplete bronchial stumps , severe neutrophil infiltrations and severe hemorrhage were observed .
the numbers of complete and incomplete histological healings and bpf complications within the subgroups are presented in table 3 .
there were no statistically significant differences in histological healing between the sgi and sgiii groups ( p = 1.00 ; p > 0.05 ) , nor between the sgii and sgiii groups ( p = 1.00 ; p > 0.05 ) .
similarly , there were no significant differences in bpf complications between the sgi , sgii and sgiii groups ( p = 0.945 ; p > 0.05 ) .
a considerable number of retrospective studies have been performed on bronchial closure techniques in human medicine , and a few experimental studies have been carried out on the basis of these retrospective studies . however , bs closure techniques , their histological healing patterns and possible cardiac , respiratory and gastrointestinal system complications after pneumonectomy have not been compared experimentally and have only been reviewed in dogs .
, manual suture has been shown to be a safe and cost - effective technique .
the superiority of stapler suture to manual suture remains questionable , and several recent studies have compared the stapler with manual suture techniques .
therefore , in the present study , manual and stapler suture techniques were used in the sgi and sgii groups , respectively .
manual suture , stapler and bs covering with flaps after manual suture closure are still in use today .
pleural flaps , patch with pedicle , pericardial grafts , pericardial fat pad grafts , diaphragm , azygous vein , pericardiophrenic pedicles , mediastinum and transposition of extra - thoracic muscles ( intercostal , serratus and latissimus dorsi ) have been used as flaps in human thoracic surgery .
intercostal muscle flaps are superior to other flaps due to their flexibility , thickness , vascularity and autogenous features , and the usage of these flaps has been recommended by a number of thoracic surgeons .
thus , in this study , pedicled intercostal externus - internus muscle was used to buttress the manual suture line of the bs closure in the sgiii group .
advised the use of simple interrupted and over - to - over suture patterns for bs closure in humans . in veterinary literature , interrupted horizontal and continuous suture patterns have been used for bs closure . in this study
, hermetically horizontal mattress sutures were performed over the excision site , without affecting the vascularity of the main stem bronchus , and the end of the bs was manually sutured with a simple interrupted suture pattern in sgi . in humans and dogs ,
ta-55 and ta-30 staplers have been reported during pneumonectomy   by the parallel approximation of the mucosal membranous and cartilaginous portions of the bronchus and applying the staple transversally to the bronchus .
if the bs is to be closed with a suture , it is important that the same surgical team perform the procedure .
therefore , in the present study , all bs closures were carried out by the same surgical team .
current literatures indicate that the application of 20 - 40 cm h2o intra - bronchial pressure is sufficient to determine the amount of bronchial air leakage before thoracic closure . similarly , the intra - bronchial pressure increases by up to 200 mmhg in humans at the time of coughing . considering these findings and the possible postoperative coughing and barking of the dogs ,
50 cm h2o pressure was applied intra - bronchially to test for air leakage . in cases of air bubbles occurring from the bs , extra vertical mattress suture(s )
pulmonary resection is associated with a considerable risk of infection ; therefore , antibiotic prophylaxis has become a routine procedure during and after pulmonary operations .
in addition , only one dose of prophylactic cephalosporin has been suggested to be an effective dosage following pneumonectomy . in this study ,
cefazolin na was administered during the postoperative period , and no infection - related complications were encountered .
radiologically , the shifted mediastinum was observed in all dogs , and no complications from the mediastinal shift were seen for one month after the operation . in humans , a history of fever and sudden onset of continuous coughing after lung resection raises the suspicion of bpf . in this study , in contrast to the results in humans , the clinical findings in the dogs with bpf were respiratory arrest and sudden onset of death .
tension pneumothorax and subcutaneous emphysema were seen in the postmortem radiographs , and necropsy of the dogs revealed the occurrence of bronchial dehiscence and confirmed the bpf .
possible cardiac , respiratory and gastrointestinal system complications after pneumonectomy have been reported in humans and dogs . in this study , five bpfs , one cardiac failure , one postoperative respiratory arrest , one cardio - pulmonary failure and one peri - operative cardiac arrest were seen in the dogs ( table 2 ) .
necropsy findings , postoperative spo2 values and ecg findings revealed these complications in this study .
it is our opinion that further studies can be planned to demonstrate the complications after pneumonectomy in dogs .
in addition , the fifth postoperative day is the most critical day for bronchial dehiscence , and the incidence of early bpf in the suture technique is 8.6% , although its incidence is 1% in the stapler technique .
the incidence of bpf following manual suture plus autogenic tissue coverage is 3.9% in humans .
the main focus of this study was not to determine the incidence of bpf in dogs , but we do report that we encountered five bpf complications in 27 dogs .
information on the inflammatory reactions between the suture material and bronchi are important to the prevention of postoperative complications . in the present study ,
neutrophil reactions with different intensities were seen after manual suture closure . in the present study ,
the stapler closure of the bronchi proved to be the preferred alternative within the three closure techniques used .
however , it is unclear which technique is superior to the others from a histological healing point of view .
it is important to note that avascular necrosis and inflammation of the bs after stapler closure have not been well explained in the literature . in the present study , the stapler technique was better than the other techniques and resulted in less severe inflammation and a faster healing process .
current literatures indicate that vascular tissue with pedicle is required for the early healing of the bs . in addition
, pedicle flaps warranted the bs healing in the critical revascularization period continuing for 3 - 4 weeks , and decreased the risk of infection .
self - vascularized flaps are reported to enhance the healing of the bs . according to algar et al .
although yamamoto et al .   indicated that intercostal flaps prevented bpf complications , demos   reported that these flaps could cause fibrosis , ossification and calcification . in our study ,
a severe inflammatory reaction was observed against the degeneration and necrosis of the flap and suture material .
there were no statistically significant differences in histological healing among the subgroups . in the present study
, we emphasize that the use of a thinner muscle flap can potentially reduce the inflammatory reaction , thus resulting in faster healing . in conclusion ,
the usage of a stapler for bs closure is the best choice according to our histological data , although it can not be considered to be a very economic technique .
manual suture plus intercostal externus- internus muscle flap technique has advantage for buttressing to bs .
there were no statistically significant differences among the subgroups with regard to bpf complications . according to the histological healing results
, the manual suture technique did not have an apparent advantage over the other techniques , but stapler closure seemed to be more acceptable than the other methods of closure .
the use of manual suture plus tissue flap technique could not be recommended due to the observation of intense inflammatory reactions following this procedure .
statistical data indicated that none of the techniques seemed to have any superiority over the others with regard to histological healing .
taking the results of the statistical analysis into consideration , all three techniques ( suture , stapler and suture plus tissue flab ) can be used for bs closure .
 the comparison of the histologic healing and bronchopleural fistula ( bpf ) complications encountered with three different bs closure techniques ( manual suture , stapler and manual suture plus tissue flab ) after pneumonectomy in dogs was investigated for a one - month period . 
 the dogs were separated into two groups : group i ( gi ) ( n = 9 ) and group ii ( gii ) ( n = 9 ) . 
 right and left pneumonectomies were performed on the animals in gi and gii , respectively . 
 each group was further divided into three subgroups according to bs closure technique : subgroup i ( sgi ) ( n = 3 ) , manual suture ; subgroup ii ( sgii ) ( n = 3 ) , stapler ; and subgroup iii ( sgiii ) ( n = 3 ) , manual suture plus tissue flab . 
 the dogs were sacrificed after one month of observation , and the bronchial stumps were removed for histological examination . 
 the complications observed during a one - month period following pneumonectomy in nine dogs ( n = 9 ) were : bpf ( n = 5 ) , peri - operative cardiac arrest ( n = 1 ) , post - operative respiratory arrest ( n = 1 ) , post - operative cardiac failure ( n = 1 ) and cardio - pulmonary failure ( n = 1 ) . 
 histological healing was classified as complete or incomplete healing . 
 histological healing and bpf complications in the subgroups were analyzed statistically . 
 there was no significant difference in histological healing between sgi and sgiii ( p = 1.00 ; p > 0.05 ) , nor between sgii and sgiii ( p = 1.00 ; p > 0.05 ) . 
 similarly , no significant difference was observed between the subgroups in terms of bpf ( p = 0.945 ; p > 0.05 ) . 
 the results of the statistical analysis indicated that manual suture , stapler or manual suture plus tissue flab could be alternative methods for bs closure following pneumonectomy in dogs . 
Introduction
Materials and Methods
Experimental group
Bronchial closure
Results
Bronchial closure
Histological findings
Discussion