Tunneled central venous catheters in children with malignant and chronic diseases: A comparison of open vs. percutaneous implantation.

PURPOSE: Tunneled central venous catheters (tCVCs) are routinely used for long-term venous access in children with cancer and chronic diseases. They may be inserted by surgical venous cut-down or percutaneously. The aim of this study was to compare the operative times and intraoperative complications of both techniques. METHODS: This study compared group A (surgical venous cut-down, years 2002-2006) with group B (percutaneous, years 2008-2012). Patient characteristics, operative times, and intraoperative complications were obtained from surgical reports. (IRB review and approval, number 6/15). Both Hickman/Broviac and Portacath catheters were included. RESULTS: 343 patients in group A and 321 patients in group B were studied. Ages at implantation and underlying diagnoses were similar. Operative time was significantly shorter in group B. Only 60% of primarily dissected veins were suitable for surgical implantation, whereas successful vessel puncture was possible in 96% (87% on the first attempt, 9% on the second). Bleeding occurred in 2% of patients in group A, and pneumothorax occurred in 1.8% of patients in group B. Early catheter dislodgement was similar in both groups. CONCLUSION: Percutaneous tCVC implantation is safe, less invasive, and faster than surgical implantation. Both techniques are feasible, and complication rates are low. LEVEL OF EVIDENCE: Level III.

The influence of controlled limb reperfusion with PGE1 on reperfusion injury after prolonged ischemia.

BACKGROUND: Controlled reperfusion of ischemic limbs has been found to be protective in limiting ischemia-reperfusion injury. We aimed to analyze local hemodynamic effects of prostaglandin E1 (PGE1) administrated during controlled reperfusion in an in vivo setting. MATERIAL AND METHODS: Twenty-four pigs underwent exposure of the infrarenal aorta and iliac vessels. Pigs were observed for 7.5 h without limb ischemia (group I). In the others, limb ischemia was produced by clamping the aorta for 6 h. Reperfusion was conducted in uncontrolled (group II), controlled (group III), and controlled fashion with addition of PGE1 (group IV) for the initial 30 min. We evaluated regional blood flow in the left common iliac artery, cardiac output, systemic vascular resistance, oxygen and glucose consumption, muscle adenosine triphosphate (ATP), and potassium levels in iliac vein. RESULTS: Benefits after reperfusion were observed in group IV compared with group III regarding regional blood flow at 60 min (P < 0.01) and 90 min (P < 0.01), glucose consumption at 30 min, (P < 0.05) and potassium regulation at 30 (P < 0.05) and 90 min (P < 0.05). CONCLUSION: The addition of PGE1 to controlled reperfusion further reduces local hemodynamic effects of ischemia-reperfusion injury compared with standard controlled and uncontrolled reperfusion in an animal model.

Inhibition of neutrophil activity improves cardiac function after cardiopulmonary bypass.

BACKGROUND: The arterial in line application of the leukocyte inhibition module (LIM) in the cardiopulmonary bypass (CPB) limits overshooting leukocyte activity during cardiac surgery. We studied in a porcine model whether LIM may have beneficial effects on cardiac function after CPB. METHODS: German landrace pigs underwent CPB (60 min myocardial ischemia; 30 min reperfusion) without (group I; n = 6) or with LIM (group II; n = 6). The cardiac indices (CI) and cardiac function were analyzed pre and post CPB with a Swan-Ganz catheter and the cardiac function analyzer. Neutrophil labeling with technetium, scintigraphy, and histological analyses were done to track activated neutrophils within the organs. RESULTS: LIM prevented CPB-associated increase of neutrophil counts in peripheral blood. In group I, the CI significantly declined post CPB (post: 3.26 +/- 0.31; pre: 4.05 +/- 0.45 l/min/m2; p < 0.01). In group II, the CI was only slightly reduced (post: 3.86 +/- 0.49; pre 4.21 +/- 1.32 l/min/m2; p = 0.23). Post CPB, the intergroup difference showed significantly higher CI values in the LIM group (p < 0.05) which was in conjunction with higher pre-load independent endsystolic pressure volume relationship (ESPVR) values (group I: 1.57 +/- 0.18; group II: 1.93 +/- 0.16; p < 0.001). Moreover, the systemic vascular resistance and pulmonary vascular resistance were lower in the LIM group. LIM appeared to accelerate the sequestration of hyperactivated neutrophils in the spleen and to reduce neutrophil infiltration of heart and lung. CONCLUSION: Our data provides strong evidence that LIM improves perioperative hemodynamics and cardiac function after CPB by limiting neutrophil activity and inducing accelerated sequestration of neutrophils in the spleen.

Aortopexy in infants and children--long-term follow-up in twenty patients.

BACKGROUND: Aortopexy has become an established surgical procedure for the treatment of tracheomalacia (TM) in infants and children. The aim of the present study was to evaluate the clinical outcome and respiratory function after aortopexy in the long term. METHODS: Between 1992 and 2006, 20 patients (6 female, 14 male) with TM were treated by bronchoscopically monitored pexis of the aorta via a right anterior thoracotomy. Patient age ranged from 4 months to 11 years (mean: 29 months). Five infants had previous surgery of esophageal atresia or tracheo-esophageal fistulae, and five other patients were operated on for gastroesophageal reflux. Postoperative tidal expiratory flow (TEF25%) was compared to age-related values. RESULTS: Mean follow-up was 7.8 years (range: 13 months to 10.7 years). There was no early or late mortality. Most patients (n = 16) showed immediate and permanent relief of symptoms. Compared to corresponding age groups, median TEF25% was slightly but not significantly decreased after aortopexy (p = 0.15). In one patient a re-aortopexy was necessary. Another patient experienced recurrent tracheo-esophageal fistula 3 years after aortopexy. CONCLUSIONS: The bronchoscopically guided aortopexy is an efficient and simple method in the surgical treatment of TM in infants and children. The follow-up data in this series of 20 patients showed improvement of respiratory function and permanent relief of symptoms in the long term.

The use of minimized extracorporeal circulation system has a beneficial effect on hemostasis--a randomized clinical study.

BACKGROUND: Conventional cardiopulmonary bypass (CPB) is associated with increased coagulation and fibrinolytic activity. A closed miniaturized bypass circuit (CorX) features a significantly reduced tubing set, an integrated pump, and an air removal system without a cardiotomy reservoir. In a prospective randomized trial, the effects on hemostasis were investigated while comparing CorX with conventional CPB in patients undergoing coronary artery bypass grafting. METHODS: Over a period of 1 year, 81 patients were randomly assigned either to the CorX system (n = 39, group A) or standard CPB system (n = 42, group B). Primary endpoints were platelet count, plasmin-antiplasmin complex (PAP), prothrombin fragments 1+2 (F1+F2), D-dimers, and fibrinogen. Secondary end-points were hematocrit, blood loss in the first 12 hours postoperatively, transfused packed red blood cells, and fresh frozen plasma in the first 24 hours postoperatively. In addition, we analyzed partial thromboplastin time, prothrombin time, and antithrombin III. RESULTS: After aortic declamping, PAP complex and prothrombin F1+F2 were significantly lower in group A than in group B. The difference in D-dimers between groups reached significance at 1 hour post-CPB. Hematocrit values at the end of CPB measured 26 +/- 6% in group A versus 22 +/- 4% in group B (P = .01). The rest of the observed parameters did not significantly differ between groups. CONCLUSION: Postoperative blood loss was not reduced in the present study. However, the use of the CorX system leads to a significant suppression of activation of coagulation and fibrinolytic cascades compared to conventional CPB, suggesting that miniaturized extracorporeal circuits are a step forward toward reduced imbalance of hemostasis in cardiac surgery.

Seven years' experience with suture annuloplasty for mitral valve repair.

OBJECTIVE: Our early experience with the mural annulus shortening suture procedure for mitral valve repair showed superior hemodynamic performance over ring annuloplasty. The aim of this study was to assess the durability of the mural annulus shortening suture procedure and evaluate our 7-year experience regarding valve function, hemodynamic performance, and clinical outcome. METHODS: Between 1996 and 2003, 222 elective consecutive patients (58.1% males; age, 59 +/- 14 years) underwent simple or complex mitral valve repair. Minimal invasive reconstruction was performed in 150 patients. For correction of annular dilatation, we used double-running 2-0 polytetrafluoroethylene sutures to reinforce the posterior circumference of the annulus. Patients were investigated prospectively by means of transthoracic echocardiography before discharge and 1 and 5 years after the operation. The mean follow up was 32 +/- 21 months (range 1-77 months). RESULTS: The operative mortality was 3.1%. Hemodynamic performance at 1 and 5 years showed low mean transvalvular gradients (2.1 +/- 0.9 and 2.0 +/- 0.8 mm Hg, respectively) and a calculated mitral valve orifice area of 3.3 +/- 0.9 cm2 and 3.1 +/- 0.6 cm2, respectively, with progressive annular dilatation from 31.2 +/- 3 mm to 33.9 +/- 4 mm at 1 year and 35.7 +/- 4 mm at 5 years (P < .01). Clinical status improved from New York Heart Association class 3.0 +/- 0.4 to 0.6 +/- 0.8 at 1 year and 0.8 +/- 0.8 at 5 years. Freedom form nontrivial residual mitral regurgitation was 82.3%, freedom from reoperation was 95.1% and actuarial survival was 87.2%, all at 77 months. CONCLUSIONS: The midterm results show satisfactory hemodynamic performance and clinical improvement. Valve competence and reoperation rates are comparable with those of other reports. Durability of the mural annulus shortening suture procedure for mitral valve repair is questioned because progressive annular redilatation occurs.

Closure of atrial and ventricular septal defects should be performed by the surgeon.

Surgeons look back on 57 years of experience in the closure of atrial septal defects (ASDs) and 46 years in the closure of ventricular septal defects (VSDs). The transcatheter approaches to repair ASDs started first in the 1980s and for VSDs 8 years later. This study sought to reveal the surgical features only given by the surgical therapy and the limitation of interventional ASD and VSD closure. A variety of surgical techniques including the minimal invasive techniques for ASD or VSD closure are well described in recent publication with good results. The surgical trend is to improve the cosmetic outcome by minimizing the size of skin incision. The latest robotically assisted technique requires only four stab wound incisions. New techniques and devices have revolutionized the transcatheter technique but could not achieve the surgical ability to close all types of ASD or VSD, control arrhythmias, and correct additional valve disease or malformation. The mortality for interventional and surgical procedures approaches zero in recent publication. The residual shunting after surgical closure of ASD varies from 2% to 7.8% versus 5% to 33% after interventional closure. General complications caused by the surgical procedure are negligible; however, the shortness of hospital stay and the cosmetic appeal is an advantage of interventional ASD closure. There is no scientific comparison of surgical vs. interventional VSD closure yet.

Initial experience with a minimized extracorporeal bypass system: is there a clinical benefit?

BACKGROUND: Drawbacks of conventional cardiopulmonary bypass (CPB) are increased inflammatory response, deteriorated coagulation and systemic organ dysfunction. A closed extracorporeal circuit (CorX) features reduced foreign surface area and priming volume. Potential benefits were studied in comparing the CorX system with conventional CPB in arrested heart coronary artery bypass grafting (CABG). METHODS: Two hundred and four patients were randomly assigned either to CorX system (n = 101, group A) or a standard CPB with cardiotomy reservoir (n = 103, group B). Besides evaluation of perioperative data and routine blood samples, we focused on lung function and perioperative bleeding. Polymorphonuclear elastase (PMNE) and terminal complement complex (TCC) served to assess inflammatory response. RESULTS: Patient demographics and operative data did not differ between groups. Postoperative lung function was not significantly impaired comparing groups A and B. Intraoperative blood loss was significantly higher in group A compared with group B (1245 +/- 947 mL vs 313 +/- 282 mL, p < 0.0001) as well as the need of fresh frozen plasma. Postoperative chest drainage did not differ significantly between groups. Two patients in each group required re-exploration due to bleeding. One hour after CPB, PMNE as well as TCC were significantly lower in group A compared with group B (PMNE: 76 +/- 44 ng/mL vs 438 +/- 230 ng/mL, p < 0.0001; TCC: 16 +/- 8 IU/mL vs 29 +/- 19 IU/mL, p < 0.0001). CONCLUSIONS: The CorX system is safe and feasible in patients undergoing CABG. Despite of markedly reduced inflammatory reaction, no clinical benefit was observed.

Echocardiographic assessment in minimally invasive mitral valve surgery.

BACKGROUND: Due to limited exposure, removal of intracavitary air and visual assessment of cardiac function during minimally invasive procedures are not always possible. We analysed the utility of intraoperative transesophageal echocardiography (TEE) and postoperative transthoracic echocardiographic (TTE) in minimally invasive mitral valve (MV) procedures. MATERIAL/METHODS: We evaluated data from 163 consecutive patients undergoing isolated minimally invasive MV replacement (n=40) or repair (n=123) via small right anterolateral thoracotomy (121 complex mitral procedures). Cardioplegic arrest was achieved using either endoaortic (n=23) or transthoracic aortic clamp (n=140). In addition to preoperative TTE, TEE was used intraoperatively before and after cardiopulmonary bypass (CPB). Postoperative TTE was performed to monitor valve function at 3 and 12 months, and at 5-year follow-up. RESULTS: Pre-CPB TEE was useful to assess valve dysfunction and assist in placement of the arterial and venous cannulas. During CPB, placement and positioning of the endoclamp were guided effectively in all but 4 patients, in whom recurrent balloon migration necessitated secondary transthoracic aortic clamping. TEE detected one acute retrograde aortic dissection and one circumflex artery occlusion. After 18.7+/-10.6 months follow-up, all patients except three improved symptomatically and had consistently good valve function. CONCLUSIONS: Intraoperative TEE is essential for minimally invasive MV surgery, because it allows immediate control of valve function before and after surgery. It is useful to detect unexpected complications requiring immediate remedy. Postoperative echocardiographic results show that minimally invasive MV surgery is a good alternative to conventional surgery even in complex MV repairs.

Successful treatment of deep sternal infections following open heart surgery by bilateral pectoralis major flaps.

OBJECTIVES: Severe sternum necrosis requiring extended resection necessitates plastic reconstruction of the resulting defect and stabilization of the chest. We analyzed the outcome of patients undergoing bilateral pectoralis major flap repair on functional and cosmetic results, chest stabilization and pulmonary function. METHODS: Twelve patients undergoing cardiac surgery between 1997 and 2001 suffered from a deep mediastinal wound infection and sternum necrosis. After a mean of two attempts of extensive wound debridement, all 12 patients underwent complete sternal resection with plastic reconstruction by bilateral pectoralis major flaps. Risk factors were obesity (n=10) and diabetes (n=11). Six months postoperatively patients underwent physical examination, pulmonary function testing and functional CT scan. RESULTS: Three patients died in hospital (two septic multiorgan failure, one heart failure) and nine were discharged with complete wound closure. One patient suffered a lethal stroke during follow-up. At 6-month follow-up no recurrent sternum infection had occurred. Chest stability was satisfactory without impairment of pulmonary function (VC 77.5+/-12.1% at follow-up vs 77.8+/-12.5% preoperatively). Mobility and force of arms and shoulder were adequate; at CT scan the maximum distance change between the former sternoclavicular joint in inspiration versus expiration was minimal. Quality of life questionnaires showed no significant limitations except a disturbed sleep and mild restriction of executing hobbies and social activities. CONCLUSIONS: Bilateral pectoralis major flap repair is a safe technique to cure severe mediastinitis necessitating complete sternal resection. Wounds close without extensive reconstructive surgery. Cosmetic results as well as stabilization of the chest were good. Patients reported an almost uncompromised quality of life without respiratory impairment.

Graded reoxygenation limits lipid peroxidation during surgical reperfusion.

BACKGROUND: Most cardiac operations with cardiopulmonary bypass (CPB) are conducted with high oxygen partial pressure. The hyperoxic reoxygenation of the ischemic heart induced by aortic declamping may be an important component of cardiac reperfusion injury. The present clinical study assessed the preventive effect of graded reoxygenation on lipid peroxidation. Malondialdehyde (MDA) levels reflect lipid peroxidation, and therefore can be used to quantify reoxygenation damage. MATERIAL/METHODS: 19 patients with coronary artery disease were enrolled consecutively and divided into two groups. In Group I, graded reoxygenation was initiated 1 min before, and continued for 9 min after aortic declamping (paO2: 50-70 mmHg, n=10). Patients undergoing conventional hyperoxic reoxygenation (paO2: >250 mmHg) on CPB (Group II, n=9) served as controls. Blood was collected before commencement of CPB, 2 min before release of the aortic crossclamp, 1 min and 10 min after release of the aortic crossclamp, and 3 hours after CPB. RESULTS: MDA levels [KM/l] did not differ between groups before CPB, but 1 min after aortic declamping MDA increased significantly more in group II (11.02 +/- 1.05; p=0.04) as compared to group I (8.16 +/- 0.74). There was no difference between groups late after reperfusion. CONCLUSIONS: Hyperoxic reoxygenation by release of the aortic crossclamp is associated with increased MDA levels immediately after aortic declamping. Graded normoxic reoxygenation therefore limits lipid peroxidation in the early reperfusion period.

Occupational exposure to inhalational anesthetics during cardiac surgery on cardiopulmonary bypass.

BACKGROUND: Eventual hazards from occupational exposure of operating room personnel to inhalational anesthetic agents cannot yet be definitively excluded. We determined if occupational exposure of operating room personnel to waste anesthetic gases during cardiopulmonary bypass (CPB) complies with the established governmental limits. METHODS: Ten adults underwent inhalational anesthesia for coronary artery bypass grafting with nitrous oxide and either sevoflurane (n = 5) or desflurane (n = 5). The administration of inhalational anesthetic agents was stopped before initiation of CPB. Gas samples were obtained before and during CPB every 90 seconds from the breathing zones of anesthesiologist (A), surgeon (S), and perfusionist (P). Time-weighted averages (TWA) over the time of exposure were calculated. RESULTS: The surgeon's exposure to nitrous oxide was 9.3 +/- 1.9 parts per million (ppm) before and 3.0 +/- 1.4 ppm during CPB (A: 6.7 +/- 1.1 ppm and 0.5 +/- 0.1 ppm; P: 3.7 +/- 1.4 ppm during CPB). Occupational exposure to desflurane was 0.21 +/- 0.10 ppm before and 0.62 +/- 0.28 ppm during CPB for the surgeon (A: 0.02 +/- 0.01 ppm and 0.02 +/- 0.003 ppm; P: 0.82 +/- 0.26 ppm during CPB), thereby exceeding the given limit of 0.5 ppm. Exposure levels of sevoflurane were below the 0.5 ppm limit at all times, as were nitrous oxide levels (threshold limit: 25 ppm). CONCLUSIONS: Although occupational exposure to inhalational anesthetic agents was low at most times during the study and none of the operating room staff complained about subjective or objective impairment or discomfort, all measures must be taken to further minimize occupational exposure, including sufficient air conditioning and routine use of waste gas scavenging systems on CPB equipment.

Comparison of hemodynamic performance of Medtronic Hall 21 mm versus St. Jude Medical 23 mm prostheses in pigs.

BACKGROUND AND AIM OF THE STUDY: The ideal prosthesis for aortic valve replacement in the small annulus remains controversial, and has yet to be defined. In previous studies, the Medtronic Hall (MH) tilting disc valve showed superior hemodynamic performance in the hemodynamically optimum orientation compared to the St. Jude Medical (SJM) bileaflet valve, especially in smaller-sized valves. Using an animal model, the hemodynamics of 21 mm MH and 23 mm SJM valves, both of which have shown identical performance in previous clinical studies, were compared. METHODS: A rotation device holding either a MH or a SJM aortic valve was implanted into eight pigs. The device allowed rotation of the implanted valve without reopening the aorta. In different orientations (best and worst orientation hemodynamically as defined previously), transvalvular pressure gradients and ventricular dimensions were measured using transesophageal echocardiography at constant hemodynamic conditions. RESULTS: In the optimum hemodynamic orientation, pressure gradients of the MH valve (6.3+/-1.7 mmHg) corresponded to those obtained with the SJM valve (6.3+/-3.7 mmHg), whereas in the worst orientation the MH showed a tendency towards higher gradients (14.0+/-2.9 versus 10.3+/-4.0 mmHg) (p = not significant). A significant increase in left ventricular enddiastolic diameter was observed for both valve designs with rotation from the optimal into the worst orientation. CONCLUSION: In the optimum hemodynamic orientation, the 21 mm MH valve matched the hemodynamic performance of the 23 mm SJM valve. Thus, implantation of the MH valve might be an alternative to root enlargement and implantation of a larger SJM valve in patients with a small aortic annulus, though optimum orientation is required.

Initial in vivo results of the new Medtronic Advantage(TM) bileaflet valve in aortic position and comparison to the SJM.

The present study investigated the Medtronic Advantage (MA) bileaflet valve in an animal model and compared the results to the St. Jude Medical (SJM) valve. Systolic performance and coronary artery flow in different orientations were studied.A rotation device holding either a MA or SJM aortic valve size 23 mm was implanted into eight pigs. Transvalvular pressure gradients and ventricular dimensions were investigated with the valves in different orientations. Coronary artery flow was measured at normal and high cardiac output. Orientation significantly influenced the hemodynamic performance of both valves. The best results for both valves were obtained with one orifice proximal to the right cusp. Pressure gradients and ventricular dimensions of the MA corresponded to the SJM. Coronary artery flow was higher for the MA. The systolic performance of the new MA bileaflet valve was similar to the SJM. During diastole, the MA showed significantly higher LAD coronary flow.

Effect of mechanical aortic valve orientation on coronary artery flow: comparison of tilting disc versus bileaflet prostheses in pigs.

OBJECTIVE: Orientation for optimal systolic performance of tilting disc and bileaflet aortic valves was defined in previous studies. The present study investigates the influence of valve orientation on coronary artery flow in an animal model. METHODS: A rotation device holding either a Medtronic Hall tilting disc (n = 4; Medtronic, Inc, Minneapolis, Minn), a St Jude Medical bileaflet (n = 4; St Jude Medical, Inc, St Paul, Minn), or a Medtronic Advantage bileaflet (n = 3) aortic valve was implanted. The device allowed rotation of the valve without reopening the aorta. Flow through the left anterior descending coronary artery was measured preoperatively and at normal versus high cardiac output after weaning from extracorporeal circulation. Measurements were performed at the best and worst hemodynamic position, as defined previously. RESULTS: Coronary flow rates were similar in all animals preoperatively (26 +/- 4.1 mL/min). After aortic valve replacement, left anterior descending flow increased significantly to 58.2 +/- 10.6 mL/min. Highest flow rates at normal cardiac output were found in the optimum orientation, especially for the Medtronic valves (Medtronic Hall, 64 +/- 8.7 mL/min; Medtronic Advantage, 64.6 +/- 11.6 mL/min; St Jude Medical, 48.3 +/- 10.3 mL/min), whereas the worst position demonstrated significantly lower left anterior descending flow, with no differences among valves (Medtronic Hall, 37.5 +/- 1.3 mL/min; St Jude Medical, 35.7 +/- 10.7 mL/min; Medtronic Advantage, 39.8 +/- 10 mL/min). Left anterior descending artery flow increased significantly with higher cardiac output. CONCLUSIONS: Coronary blood flow was significantly influenced by mechanical aortic valve implantation and the orientation of prostheses. For both valve designs, the previously defined optimum orientation with respect to pressure gradients and turbulence demonstrated the highest left anterior descending flow rates. Even in its optimum orientation, the St Jude Medical valve showed significantly lower coronary flow than the other valves.

Surgical treatment of tracheomalacia by bronchoscopic monitored aortopexy in infants and children.

BACKGROUND: Aortopexy has become an established surgical procedure for the treatment of severe tracheomalacia (TM) in infancy. However, postoperative outcome may be improved by intraoperative bronchoscopic control of the aortopexy. METHODS: Between 1992 and 2000, 16 infants and children (2 female, 14 male) with TM were treated by pexis of the aorta via a right (15 patients) or left (1 patient) anterior thoracotomy. Patients age ranged from 4 to 122 months (mean, 26 mon). Three infants had previous surgery for esophagus atresia and tracheoesophageal fistula. Another four patients were operated for gastroesophageal reflux. In all cases, the aortopexy was monitored intraoperatively by bronchoscopy. Respiratory function was verified for each patient by comparing pre- and postoperative tidal expiratory flow values (TEF 25% in ml/sec). RESULTS: Mean follow-up was 36 months (range, 2 to 60 mo). There was no intraoperative or postoperative mortality. 13 patients showed permanent relief of symptoms. Postoperative median TEF 25% increased significantly compared with preoperative values (81 ml/sec vs. 56 ml/sec; p = 0.016). In one patient repeat aortopexy was necessary. CONCLUSIONS: Aortopexy through a right anterior thoracotomy is an efficient and feasible method in the surgical treatment of TM in infancy and, therefore, can improve postoperative respiratory function. Intraoperative bronchoscopy is advantageous.