Mucociliary function in autotransplanted, allotransplanted, and sleeve resected lungs

Hypoxic Gene Expression of Donor Bronchi Linked to Airway Complications after Lung Transplantation

RATIONALE

Central airway stenosis (CAS) after lung transplantation has been attributed in part to chronic airway ischemia; however, little is known about the time course or significance of large airway hypoxia early after transplantation.

OBJECTIVES

To evaluate large airway oxygenation and hypoxic gene expression during the first month after lung transplantation and their relation to airway complications.

METHODS

Subjects who underwent lung transplantation underwent endobronchial tissue oximetry of native and donor bronchi at 0, 3, and 30 days after transplantation (n = 11) and/or endobronchial biopsies (n = 14) at 30 days for real-time polymerase chain reaction of hypoxia-inducible genes. Patients were monitored for 6 months for the development of transplant-related complications.

MEASUREMENTS AND MAIN RESULTS

Compared with native endobronchial tissues, donor tissue oxygen saturations (Sto2) were reduced in the upper lobes (74.1 ± 1.8% vs. 68.8 ± 1.7%; P < 0.05) and lower lobes (75.6 ± 1.6% vs. 71.5 ± 1.8%; P = 0.065) at 30 days post-transplantation. Donor upper lobe and subcarina Sto2 levels were also lower than the main carina (difference of -3.9 ± 1.5 and -4.8 ± 2.1, respectively; P < 0.05) at 30 days. Up-regulation of hypoxia-inducible genes VEGFA, FLT1, VEGFC, HMOX1, and TIE2 was significant in donor airways relative to native airways (all P < 0.05). VEGFA, KDR, and HMOX1 were associated with prolonged respiratory failure, prolonged hospitalization, extensive airway necrosis, and CAS (P < 0.05).

CONCLUSIONS

These findings implicate donor bronchial hypoxia as a driving factor for post-transplantation airway complications. Strategies to improve airway oxygenation, such as bronchial artery re-anastomosis and hyperbaric oxygen therapy merit clinical investigation.

Outcomes of Sleeve Lobectomy versus Pneumonectomy for Lung Cancer

Background

Sleeve lobectomy for lung cancer in close proximity to or involving the carina is widely accepted. Operative morbidity and mortality rates, recurrence, and survival rates have varied considerably across studies.

Materials and Methods

From March of 2005 to July of 2010, sleeve lobectomy was performed in 19 patients and pneumonectomy was performed in 20 patients. In this paper, the results of sleeve lobectomy and pneumonectomy for patients with lung cancer will be compared and evaluated.

Results

There were no postoperative complications in either group, but there was one mortality in the pneumonectomy group. There was better preservation of pulmonary function in the sleeve lobectomy group than the pneumonectomy group (p=0.066 in FVC, p=0.019 in FEV1). The 3-year survival rates were 46.7% in the sleeve lobectomy group and 54.5% in the pneumonectomy group (p=0.505). The 3-year disease-free survival rates were 38% in the sleeve lobectomy group and 45.8% in the pneumonectomy group (p=0.200).

Conclusion

Sleeve lobectomy for lung cancer showed low mortality, low bronchial anastomotic complication rates, and good preservation of pulmonary function.

Vagal control of mucociliary clearance in murine lungs: a study in a chronic preparation

We conducted several experiments that focused on the effect of vagal control on mucociliary clearance (MCC) in murine lungs. We hypothesized that loss of vagal control by chronic denervation (i.e. vagotomy) would reduce both basal MCC and the increase in MCC typically observed upon stimulation of capsaicin sensitive C-fibers. Vagotomy was performed on the right side of C57BL/6 mice and MCC was measured 5 days later. Mucociliary clearance was measured by gamma scintigraphy after oropharyngeal aspiration of the radioisotope (99m)technetium and was expressed as the amount of radioactivity removed from the right lung 6h later. Baseline MCC was unaffected by vagotomy, averaging 6.5+/-4.9% and 6.8+/-5.8%, in 6 vagotomized and 6 non-vagotomized mice (controls), respectively. Mucociliary clearance increased significantly to 12.7+/-5.9% in 9 non-vagotomized mice treated with 1.6 x 10(-9) M capsaicin, a vagally-mediated, nociceptor stimulus (p=0.041). Capsaicin was admixed with (99m)technetium and administered by oropharyngeal aspiration. In contrast, MCC was unchanged from control values in 9 vagotomized, capsaicin-treated animals, averaging 6.0+/-5.5% (p=0.024). These findings suggest that loss of vagal control through denervation does not affect basal MCC in C57BL/6 mice, but does appear to reduce the capacity of mice to respond to nociceptor agents that stimulate MCC. These data could have implications for patients whose lungs are denervated due to lung transplantation, since they may be at risk for an inadequate MCC response to inhaled irritants and inflammatory mediators, which are also nociceptor stimuli.

Should lung transplant recipients routinely perform airway clearance techniques? A randomized trial

BACKGROUND AND OBJECTIVE

Despite the widespread use of airway clearance (AC) techniques to clear excessive secretions and improve lung function, little is known about their efficacy following lung transplantation (LTx). This study compared the effects of two AC strategies (proactive vs reactive) on a range of clinical outcomes following LTx.

METHODS

A prospective randomized trial was conducted. Uncomplicated patients were recruited 1 month postoperatively. Patients performed AC using positive expiratory pressure either twice daily (proactive strategy) or only in the presence chest infection (reactive strategy). Lung function (FEV(1) and FVC), CXR (Brasfield score) and bronchoscopic airway characteristics (anastomotic healing, patency and secretions) were assessed at 1, 2 and 3 months postoperatively. Adherence was measured.

RESULTS

Of 60 consecutive patients, 36 (18 proactive, 18 reactive) were recruited and completed the study. Both groups improved lung function (FEV(1) 72 +/- 4% to 81 +/- 4%, P < 0.0001; FVC 69 +/- 3% to 81 +/- 3%, P < 0.0001) and Brasfield scores (17.8 +/- 0.5 to 19.8 +/- 0.5, P < 0.002) over the study period. No significant differences for any outcome were found between the two groups. The vast majority of patients had fully healed, 100% patent anastomoses without secretions at 3 months. There were no significant differences between the two groups in airway characteristics and the incidence of chest infection. Adherence to both strategies was high (84% proactive, 100% reactive).

CONCLUSIONS

Proactive AC following lung transplantation was not associated with a reduced incidence of respiratory infection, alteration of CXR findings or improvement in airway characteristics.

Mucociliary clearance and sense of smell following management of Le Fort maxilla fractures

OBJECTIVE

To assess mucociliary transport and olfaction in patients after Le Fort fractures.

STUDY DESIGN

Forty-one patients were enrolled who had sustained a Le Fort fracture during the preceding five years. Control group consisted of students. Olfaction and mucociliary transport were examined in all subjects. A capillary with saccharine was placed on the inferior nasal concha, and time was recorded in which the subject tasted sweetness in the mouth. Results were subject to statistical analysis. Patients with allergy, sinus disease and smokers were excluded from the examination.

RESULTS

Disturbance of mucociliary transport and olfaction turned out to be statistically dependent on the type of fracture and management.

CONCLUSIONS

Le Fort fracture might be complicated by compromised mucociliary clearance and olfactory disturbances.

Effects of Bronchial Transection and Reanastomosis on Mucociliary System

STUDY OBJECTIVES

The mechanisms involved in the impairment of mucociliary function after lung transplantation are not completely understood. The purpose of the present study was to isolate the effects of unilateral bronchial transection and reanastomosis in a rat model.

DESIGN

In situ bronchial mucociliary transport (MCT) was determined proximal and distal to the bronchial anastomosis, as well as in the right bronchus, in 48 rats classified into six groups: intact rats, and rats at 1 day, 2 days, 7 days, 15 days, and 30 days after bronchial transection and reanastomosis of the left main stem bronchus. In vitro mucus transportability and mucus contact angle were studied in another group of eight rats after 1 week of surgery.

RESULTS

Distal to the anastomosis site, left bronchus in situ MCT (mean +/- SD) was 0.26 +/- 0.19 mm/min for the intact group, and 0.11 +/- 0.13 mm/min, 0.07 +/- 0.04 mm/min, 0.03 +/- 0.04 mm/min, 0.07 +/- 0.12 mm/min, and 0.05 +/- 0.06 mm/min for 1 day, 2 days, 7 days, 15 days, and 30 days after surgery, respectively (all significantly reduced, p < 0.05). No intergroup differences were found proximal to the anastomosis (p = 0.30). When comparing the left and right bronchi, differences were detected in both distal (p < 0.0001) and proximal sides (p = 0.0001). No significant differences in mucus transportability in vitro were found (p = 0.15). Mucus contact angle of the left bronchus (52.8 +/- 20.5 degrees ) was significantly greater than that of the mucus from the right bronchus (34.4 +/- 12.9 degrees; p < 0.05).

CONCLUSIONS

We conclude that bronchial transection and reanastomosis lead to a marked impairment of MCT in distal airways, which can in part be explained by alterations in the surface properties of mucus.

Bronchial transsection and reanastomosis in pigs with and without bronchial arterial circulation

BACKGROUND

The bronchial artery may be vital to the bronchi and lung parenchyma, but results of lung transplantation have raised doubts. This study was performed to examine the effect of bronchial arterial devascularization on bronchial morphology after bronchial transsection and reanastomosis.

METHODS

In 6 pigs (study group), the left main bronchus was transsected, reanastomosed, and devascularized. Six control pigs had the same operation without devascularization. After 1 week, bronchial arterial angiography was performed, and specimens were examined with conventional histology and scanning electron microscopy.

RESULTS

Histology showed significant changes (inflammation, edema, and fibrosis) in bronchi and lung parenchyma of the study group compared with the unoperated side (p = 0.028) and with the control group (p = 0.050). Scanning electron microscopy showed significant ciliary denudation in the study group's left bronchus compared with the unoperated side (p = 0.043) and with the control group (p = 0.0071).

CONCLUSIONS

The loss of cilia of the bronchial epithelium and the occurrence of inflammation, edema, and fibrosis in bronchi and lung parenchyma 1 week postoperatively were significantly related to the absence of the bronchial arterial circulation.

Experimental tracheal reconstruction with a rotated right stem bronchus

BACKGROUND

To reconstruct a longer tracheal defect, a safe method other than end-to-end anastomosis is necessary.

METHODS

Nine mongrel dogs underwent right thoracotomy. The lobes of the right lung other than the apical lobe were resected, keeping the bronchi in place to be manipulated to extend the right stem bronchial conduit. The trachea was resected for a 10-cartilage-ring length. The modified right stem bronchus was then brought into the mediastinum by rotation in the frontal plane. An end-to-end anastomosis was made. The right apical lobe, once separated, was then reanastomosed end-to-side. Ciliary transport was studied.

RESULTS

Eight of the 9 dogs tolerated the surgical procedure well, and the reanastomosed right apical lobe remained well expanded for 1 year or more postoperatively. The inverted segment did not show any cranial ciliary transport movement.

CONCLUSIONS

A large tracheal defect more than 10 rings in length can be reconstructed using a rotated right stem bronchus with the right apical lobe reanastomosed. The inverted bronchial segment loses its cranial ciliary transport movement.

Medium-term patency and anatomic changes after direct bronchial artery revascularization in lung and heart-lung transplantation with the internal thoracic artery conduit

OBJECTIVE

Our purpose was to study the 2-year patency of direct bronchial artery revascularization in lung transplantation. We wanted to clarify whether the revascularized bronchial artery system is functional after 2 years, whether bronchial artery vascularity changes with time, and whether posttransplantation bronchial artery disease is arteriographically evident after 2 years.

METHODS

Bronchial artery revascularization is performed by anastomosing the internal thoracic artery to as many bronchial artery orifices in the donor descending aorta as possible. Twenty-three patients surviving 2 years or more have had internal thoracic artery-bronchial arteriography performed 1 month and 2 years after transplantation. One-month and 2-year arteriograms have been compared.

RESULTS

Two-year patency of the internal thoracic artery conduit was 100%. The appearance of the bronchial arteries was unchanged after 2 years in 11 patients. A unilateral or bilateral increase in vascularity was found in two and seven patients, respectively. In three patients new vessels, not visible on the first arteriogram, had appeared. In four patients one or more small vessels visible on the first arteriogram had disappeared on the second arteriogram. We have found no arteriographic signs of bronchial artery disease, such as stenosis of the bronchial arteries, and no arteriographic evidence of arteriosclerotic disease in the internal thoracic artery.

CONCLUSION

The internal thoracic artery is an excellent conduit for bronchial artery revascularization, with a 2-year patency of 100% in 23 patients. Only minor changes in the bronchial arteriograms have been found.

Anaesthesia for patients after lung transplantation

PURPOSE

The purpose of this article is to review the literature on post lung transplant patients presenting for surgery and anaesthesia and to provide insight into their perioperative management.

SOURCE

Articles and books were identified via a Medline search and through a review of the bibliographies of these sources.

PRINCIPLE FINDINGS

Single and double lung transplantation is becoming more common and the period of survival is increasing. As a result, more of these patients are presenting for surgery and anaesthesia. Also, it is increasingly likely that these patients may present, either for emergency or elective surgery, to anaesthetists with limited experience in this field. These patients have considerable medical, physiological and pharmacological problems which need to be understood.

CONCLUSION

Anaesthesia, local, regional, or general, can be safely delivered to these patients provided that the physiology and pathophysiology of the transplanted lung, the pharmacology of the immunosuppressive agents, and the underlying surgical condition are understood.

Aerosol clearance by the bronchial circulation

The importance of the tracheobronchial circulation in supporting mucociliary clearance is unclear. In anesthetized, ventilated sheep (n = 8), mucociliary transport of 99mTc-labeled sulfur colloid particles (2.1 microns) was measured during control perfusion of the cannulated bronchial branch of the bronchoesophageal artery or when perfusion through this artery was stopped. Particle retention 60 min after aerosol delivery of particles averaged 55% during control bronchial blood flow conditions. When perfusion was stopped, average retention was significantly increased to 76% (p < 0.05). These results indicate that the bronchial vasculature exerts an important modulating influence on mucociliary transport.

Importance of airway blood flow on particle clearance from the lung

The role of the airway circulation in supporting mucociliary function has been essentially unstudied. We evaluated the airway clearance of inert, insoluble particles in anesthetized ventilated sheep (n = 8), in which bronchial perfusion was controlled, to determine whether airway mucosal blood flow is essential for maintaining surface transport of particles through airways. The bronchial branch of the bronchoesophageal artery was cannulated and perfused with autologous blood at control flow (0.6 ml.min-1.kg-1) or perfusion was stopped. With the sheep in a supine position and after a steady-state 133Xe ventilation scan for designation of lung zones of interest, an inert 99mTc-labeled sulfur colloid aerosol (2.1-microns diameter) was deposited in the lung. The clearance kinetics of the radiolabeled particles were determined from the activity-time data obtained for right and left lung zones. At 60 min postdeposition of aerosol, average airway particle retention for control bronchial blood flow conditions was 57 +/- 7 (SE)% for the right and 53 +/- 8% for the left lung zones. Clearance of particles was significantly impaired when bronchial blood flow was stopped, e.g., right and left lung zones averaged 77 +/- 6 and 76 +/- 7% at 60 min, respectively (P < 0.05). These data demonstrate a significant influence of the bronchial circulation on mucociliary transport of insoluble particles. Potential mechanisms that may account for these results include the importance of the bronchial circulation for nutrient flow, maintenance of airway wall temperature and humidity, and release of mediators and sequelae associated with tissue ischemia.

Airway mucus and epithelial function in a canine model of single lung autotransplantation

Impaired mucociliary function following lung transplantation has been reported in several human and animal studies. This could be a result of altered ciliary function or mucus properties or both. We assessed airway epithelial function by means of transepithelial potential difference (PD) measurements and physical analysis of mucus. Six mongrel dogs underwent single lung autologous transplantation. Measurements were performed preoperatively and 1, 2, 4, and 10 months postoperatively. At 1 and 2 months postoperatively, there was a significant fall in PD for the transplanted, left mainstem bronchus only (-13.5 +/- 1.7 mV at 1 month and -14.6 +/- 1.7 mV at 2 months postoperatively vs -18.6 +/- 2.3 mV preoperatively, baseline; p < 0.001 for both). The PD values in the small airways, right mainstem bronchus, and the trachea remained unchanged. At 2 months postoperation, the mucus collection rate on the left side was increased (p = 0.03), while the mucus viscoelasticity was decreased (p = 0.04). By 4 months postoperation, all epithelial parameters had returned to baseline, and there was no difference in radioaerosol clearance between the two lungs. The PD decrease and alterations in secretion rate and viscoelasticity reflect disturbed epithelial functional integrity at the site of anastomosis still present at 2 months postoperation. Recovery of bronchial epithelial function and clearance in canine studies of lung autotransplantation after healing of the anastomosis area suggest that persistent impairment of lung clearance observed in some long-term human lung transplantation survivors may be due to other mechanisms such as impaired healing or epithelial function or both, during immunosuppressive therapy. Mucociliary function in the anastomosis area is compromised until complete healing ensues; we speculate that chest physiotherapy may aid in overcoming this obstacle.

Routine immediate direct bronchial artery revascularization for single-lung transplantation

Ischemia of the donor airway remains a significant cause of morbidity after single-lung transplantation; serious manifestations may occur early (anastomotic dehiscence) or late (stricture). Direct, immediate revascularization of the donor bronchial arteries, using the recipient internal thoracic artery, was performed in 10 consecutive recipients of single-lung transplants for whom we procured the organs. Mean recipient age was 52.6 years (range, 43 to 59 years); 6 were male and 4 female. Recipient diagnoses were emphysema (6), obliterative bronchiolitis (2), pulmonary fibrosis (1), and primary pulmonary hypertension (1). Bronchial artery revascularization initially prolonged the ischemic time by only 15 to 20 minutes; this improved with experience. There was one early death and two late deaths in the series. Internal thoracic arteriography was performed 7 to 10 days postoperatively in all 9 surviving patients. There was excellent perfusion of the donor bronchial arteries in 7 of these 9 patients. Bronchoscopy was performed when clinically indicated. No patient had early or late airway healing complications at a median follow-up of 13 months (range, 6 to 16 months). We conclude that direct, immediate bronchial artery revascularization is feasible on a routine basis for single-lung transplantation, and airway healing has been excellent.

In vitro transport of carbon in the trachea of veal calves

Carbon transport was studied in vitro in preparations of trachea and bronchus from veal calves. The mean velocity varied from 4.2 mm/min in the main bronchi to 6.3 mm/min in the ventral trachea. In some locations no transport was observed. Stereomicroscopic evaluation of Alcian blue-phloxine stained mucosal surfaces revealed differences in the appearance of the mucus layer between locations with and without mucus transport. It is concluded that quality and integrity of the mucus layer play an important role in mucus transport.

Radical systematic mediastinal lymphadenectomy in non-small cell lung cancer: a randomized controlled trial

The value of radical systematic lymphadenectomy in the treatment of bronchial carcinoma is controversial. In a randomized controlled clinical trial, radical lymphadenectomy was compared with conventional node dissection in 182 patients with non-small cell lung cancer. Comparison of short-term results revealed a significantly longer operating time in those undergoing systematic lymphadenectomy, but overall morbidity and mortality rates were comparable between groups. However, there were complications associated with radical lymphadenectomy such as prolonged air leakage and haemorrhage. Interim analysis of results at a median follow-up of 26.8 months showed no significant influence of radical lymphadenectomy on local recurrence-free interval, metastasis-free interval or cancer-related survival. In conclusion, radical systematic lymphadenectomy is a safe operation that leads to a better staging of non-small cell lung cancer, but its prognostic benefit is questionable.

Tracheobronchial sleeve resection in children and adolescents

Bronchoplastic techniques preserving lung parenchyma allow resection and reconstruction of the major bronchi and carina and are widely used in adults. The smaller and more delicate airways of children make such operations more demanding, but successful outcome can still be achieved with particular attention to technique. The authors treated 12 patients age 8 to 19 years (mean, 13.8 years) over a 12-year period. Ten patients had tumors of the airway: carcinoid (4), mucoepidermoid (2), malignant fibrous histiocytoma (1), adenocarcinoma (1), granular cell (1), and invasive fibrous tumor (1); and 2 had nonneoplastic strictures. Previous operative treatment included incomplete local excision in 2 and laser ablation in 1. Carinal resection and reconstruction was performed in 6 patients, main-stem bronchial resection in 3, and sleeve lobectomy in 3. There was one death after a complex airway reconstruction for extensive mediastinal fibrosis involving the airway. Postoperative morbidity consisted of prolonged atelectasis in 3 patients. Residual malacia in 1 patient with postpneumonectomy syndrome required further tracheobronchial resection. Follow-up is complete (mean, 64 months; range, 7 to 130). There has been no anastomotic stenosis or tumor recurrence. Preservation of lung function is expected in all patients. In 7 patients, bronchoscopy 4 months to 11 years postoperatively confirmed anastomotic patency and growth. The understanding of bronchoplastic techniques and precise attention to technical detail should allow these procedures to be successfully performed in pediatric patients.

Impairment of bronchial mucociliary clearance in long-term survivors of heart/lung and double-lung transplantation. The Paris-Sud Lung Transplant Group

The study objective was to investigate bronchial mucociliary clearance after heart/lung and double lung transplantation. Bronchial mucociliary clearance was measured using a noninvasive radioaerosol technique: 99mTc-labeled albumin was aerosolized using a spinning-top generator (mass median aerodynamic diameter, 7.5 mu; geometric standard deviation, 1.5 mu). Radioactivity counts were acquired during 60 min with a gamma camera. A region of interest was drawn over the right lung delineated by a 133Xe lung ventilation image. Bronchial mucociliary clearance was assessed as the percentage of decrease in radioactivity per hour calculated on time-activity curves fitted by a monoexponential model. To exclude patients with acute lung rejection, opportunistic lung infection, and obliterative bronchiolitis, all patients with transplants underwent pulmonary function tests and bronchoscopic examination before clearance measurement. Eight heart/lung and five double-lung nonsmoking transplant patients with normal lung histology were studied 19.3 +/- 4.0 mo after surgery and compared to nine normal nonsmokers. A similar proximal deposition of the aerosol was obtained in patients with transplants and normal subjects; skew values of distribution histograms of aerosol radioactivity counts were 2.1 +/- 0.2 and 1.8 +/- 0.1, respectively, and the ratios between central and peripheral 99mTc radioactivity counts were 2.4 +/- 0.1 and 2.3 +/- 0.2, respectively. No significant difference was observed in bronchial clearance values between patients with heart/lung and double-lung transplants (26.4 +/- 3.0 percent/h vs 35.9 +/- 3.5 percent/h). Conversely, bronchial clearance was significantly lower in transplant recipients (30.0 +/- 2.5 percent/h) than in normal controls (58.7 +/- 6.2 percent/h; p < 0.001). This decreased bronchial clearance can be expected to increase the risk of lung infection in long-term survivors of heart/lung and double-lung transplantation.

Critical care management of lung transplant recipients

In the last 10 years, lung transplantation has become an increasingly common procedure for patients with end-stage respiratory disease. Although long-term survival can be achieved, there is still significant morbidity within the first year. Early postoperative problems that may be anticipated include respiratory insufficiency, airway anastomotic problems, hemorrhage, infection, and episodes of acute rejection. These problems and others make the immediate perioperative period particularly challenging. With aggressive management, however, the probability of a successful outcome can be enhanced.