J Thorac Cardiovasc Surg 1994;107:945-947
© 1994 Mosby, Inc.
Bronchial circulation and airway complications after lung transplantation: Possible role of pulmonary rejection
Motoshi Takao, MD,
Hajime Tanabe, MD,
Isao Yada, MD,
Syoji Namikawa, MD,
Hiroshi Yuasa, MD,
Minoru Kusagawa, MD
Department of Thoracic and Cardiovascular Surgery
Mie University, School of Medicine
2-174 Edobashi
Tsu, Mie 514, Japan
To the Editor:
We read with interest the article by Drs Inui and associates.
1 They demonstrated the correlation between bronchial circulation and histologic changes in donor bronchi after lung transplantation in a model of modified lung transplantation in which the graft bronchi are susceptible to ischemia. They also clearly showed the advantageous effect of early routine administration of an adequate dose of prednisolone on bronchial circulation after lung transplantation, and they reviewed recent clinical experience. 2 It is unfortunate, however, that they did not mention the rejection grade in each lung with relation to bronchial mucosal blood flow and histologic findings in donor bronchi. Using canine single lung allotransplantation, we 3 showed that bronchial blood flow at the graft bronchi is much lower in animals with acute pulmonary rejection than in animals with no rejection whereas all of the animals are immunosuppressed with cyclosporine (10 mg/kg per day) and azathioprine (5 mg/kg per day). Furthermore, successful immunosuppressive augmentation including steroid therapy can reverse the decrease in donor bronchial blood flow during acute pulmonary rejection in conjunction with reversal of histologic changes of the graft bronchi, which may indicate rejection itself. 4,5 However, the graft bronchi seem to be more susceptible, in terms of histologic changes, to acute pulmonary rejection during the early postoperative period than during the late postoperative periodonce donor bronchial blood flow has recovered to normal 5 (Fig. 1). The histologic changes of donor bronchi may be closely related to ischemic change besides acute rejection in the early postoperative period. Therefore, we believe that pulmonary rejection is definitely a risk factor for airway complications after lung transplantation, particularly under conditions susceptible to ischemia: lung transplantation rather than heart-lung transplantation, poor lung preservation rather than good lung preservation, and early postoperative period rather than late postoperative period. Therefore, we wonder if the degree of acute pulmonary rejection could explain intergroup and intragroup variations in histologic changes at the donor bronchi in their experiment and determine the possible role of prednisolone in protecting the graft bronchi: inhibition of vascular rejection, antiischemic effect, or both. Much needs to be learned about these mechanisms to define more closely the therapeutic regimens to cope with airway complications after lung transplantation—new potent immunosuppressive agents or improvement of protection for pulmonary ischemic damage; otherwise, revascularization of donor bronchial arteries.
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Fig. 1. Correlation of histologic grades between pulmonary rejection and donor main bronchi (canine left lung allotransplantation).Vertical axis shows histologic changes of the donor main bronchus:A, few significant changes;B, edema in submucosal layer;C, perivascular mononuclear cell infiltration;D,C +B;E, diffuse perivascular infiltration and more edema; F, necrotizing vasculitis of muscular arteries and bleeding around small vessels.Horizontal axisshows histologic grading of pulmonary rejection according to International Society for Heart Transplantation classification. Closed squares, Dog killed by 21 days after transplantation (17.9 ± 3.5 days).Open square, Dog killed thereafter (46.9 ± 24.0days).
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References
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Inui K, Schafer HJ, Aoki M, et al. Bronchial circulation after experimental lung transplantation: the effect of long-term administration of prednisolone. J THORAC CARDIOVASC SURG 1993;105:474-9.[Abstract]
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Miller JD, DeHoyos A. An evaluation of the role of omentopexy and of early perioperative corticosteroid administration in clinical lung transplantation. J THORAC CARDIOVASC SURG 1993;105:247-52.[Abstract]
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Tanabe H, Yada I, Namikawa S, Kusagawa M. Early detection of lung rejection by measurement of bronchial mucosal blood flow using laser Doppler flowmeter. Transplant Proc 1989;21:2590-1.[Medline]
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Takao M, Katayama Y, Onoda K, et al. Significance of bronchial mucosal blood flow for the monitoring of acute rejection in lung transplantation. J Heart Lung Transplant 1991;10:956-67.[Medline]
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Takao M, Katayama Y, Tanabe H, et al. Histologic changes in donor bronchi may explain the reduced mucosal blood flow seen during acute lung allograft rejection. J Heart Lung Transplant1992;11:994-1000.
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Tanabe H, Takao M, Hiraiwa T, et al. New diagnostic method for pulmonary rejection by measurement of bronchial mucosal blood flow. J Heart Lung Transplant 1991;10:968-74.[Medline]
