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JOURNAL OF THE NATIONAL MEDICAL ASSOCIATION

JANUARY, 1976

A Serial Comparison of Bronchial Stump Closure Techniques Following Pneumonectomy* RICHARD N. SCOTT, M.D., Senior Surgeon, Surgery Branch, National Cancer Institute, National Institutes of Health, Bethesda, Maryland

PERHAPS the most feared surgical complication following pulmonary resection is a bronchopleural fistula. Because of the high morbidity and mortality associated with this complication, thoracic surgeons have devised numerous technical approaches designed to strengthen bronchial stump closures. These approaches have included alterations in the technique of bronchial stump closure, the use of a variety of sutures and the addition of autologous tissue flaps and synthetic adhesives to the routine operative procedure. However, despite these efforts, the incidence of bronchopleural fistula following pneumonectomy varies from 2.7 to 6.7%. Even more alarming than the incidence of this complication is its overall mortality rate, which has been reported as high as 23.1 %. Preliminary studies in our laboratory have suggested that the inflammatory response between suture and bronchus also affects the strength of bronchial stump closure. The purpose of this presentation is to provide a serial evaluation of the inflammatory response associated with commonly employed suture materials for bronchial stump closure following pneumonectomy. MATERIALS AND METHODS

Ninety adult mongrel dogs weighing between 20-25 kg were anesthetized with intravenous sodium barbiturate (sodium thiamylal surital) and intubated. Respiration was maintained by means of an intermittent insufflating apparatus. Left thoracotomy was performed through the fifth intercostal space and *Awarded the Charles R. Drew Surgical Forum Prize at the 80th National Medical Association Convention, August 10-15, 1975.

the left pulmonary artery, pulmonary veins and bronchial vessels were successively ligated. Trauma to the bronchus and its blood supply was avoided. The bronchus was then transected 1.5 cm distal to the carina. The animals were divided into three groups. Group L. In this group, 35 bronchial stumps were closed with interupted 3-0 silk sutures using the modified open technique of Sweet. Dogs were sacrificed at 24 hours, three, five, seven, 10, and 14 days postpneumonectomy. An endotracheal tube was inserted and the left thoracic cavity opened through the previous incision. After the position of the endotracheal tube was verified at the level of the carina, the right bronchus was dissected free and completely occluded. The endotracheal tube was connected to a cylinder of compressed air with an intervening mercury manometer to measure endotracheal pressure. The left chest was filled with sterile saline and the endotracheal pressure increased until an air leak at the bronchial stump was observed. This pressure was designated as the leakage pressure. All stumps were removed for histological evaluation and routine examination performed on slides stained with Meyer's hematoxylin and eosin. Special stains employed included Wilder's reticulin and Masson's trichrome. The average number of polymorphonuclear leukocytes per high power field along the suture line was counted for each of the specimens and an average for each specimen calculated. This population of means was then averaged for each time period following pneumonectomy. Collagen production was estimated using a scale of 1 to 4+. One plus was considered as

Vol. 68, No. 1

Bronchial Stump Closure

early meshwork of reticulin, small collagen fibers and blood vessels; 2+ was characterized by areas of active collagen formation interspersed with small blood vessels; 3+ by foci of solid collagen without intervening blood vessels; and 4+ by a predominance of areas of relatively avascular, collagenous tissue within the line of closure. Group II. The second group consisted of thirty bronchial stumps closed with an automatic stapling device. The technique of pneumonectomy, the bronchial stump ages at the time of study, the method of determining leakage pressures, and the histological evaluation were identical to those of Group I. Group III. The third group consisted of 25 bronchial stumps closed with interrupted 3-0 nylon sutures as described in Group I. Nylon stumps were evaluated at five, seven, 10, and 14 days postpneumonectomy. The studies performed were idental to those described for Groups I and II. RESULTS

After 24 hours, minimal histological differences existed between the silk and staple closed bronchial stumps. Marked differences were first noted at three days following pneumonectomy. The average number of polymorphonuclear leukocytes (PMN's) per high power field (HPF) in silk closed bronchial stumps at three days (126.42 + 95.18 SD) was significantly greater (p < .001) than that present in the staple closed stumps (29.14 + 29.40 SD). This marked difference in inflammatory response reached its greatest limits at five days postpneumonectomy when the average number of PMN's per HPF of silk closed stumps (238.19 + 23.28 SD) was more than six times that of the staple closed stumps (34.95 ± 4.24 SD; p < .0001). After seven days, the difference in inflammatory response between silk and staple closures persisted but was less pronounced. At 14 days postpneumonectomy, the number of PMN's per HPF in silk closed stumps (195.0 + 11.54 SD) remained significantly greater (p < .0001) than that present in the staple closed stumps (27.25 + 2.99) (Fig. 1). Nylon suture was selected as representa-

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tive of a common monofilament material used for bronchial stump closure. Since there was relatively little difference between silk and staple inflammatory responses for the first three days postpneumonectomy, nylon closures were first evaluated on the fifth postoperative day. At this time, the number Silk

Staple Nylon

250 U. s

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150

,100. 500 1

3

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DAYS FOLLOWING PNEUMONECTOMY

Fig. 1. Quantitation of inflammation in silk, nylon and staple closed bronchial stumps.

of PMN's per HPF in nylon stump closures (80.2 + 18.13 SD) was significantly less (p < .001) than that present in silk closures (238.19 + 23.28 SD). However, the number of PMN's per HPF in the five day old staple closures (34.95 + 4.24 SD) was less than one-half that of the nylon closures (80.2 + 18.13 SD). After the fifth postoperative day, the inflammatory response associated with nylon closures was always less than silk closures and greater than staple closures (Fig. 1). The estimated collagen production in the silk and staple bronchial stump closures revealed little variation at 24 hours postpneumonectomy. However, at three days the staple closed stumps demonstrated an early meshwork of reticulin, small collagen fibers, and blood vessels. The silk closed stumps showed no collagen production at this time. Marked variation in collagen production was first noted at five days when the staple closures demonstrated foci of solid collagen without intervening blood vessels and the silk closures were forming only an early meshwork of small collagen fibers and blood vessels. After seven days, the differences in collagen production between the two types of closures was less marked, and almost idental

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JOURNAL OF THE NATIONAL MEDICAL ASSOCIATION

by the tenth postoperative day. Collagen production associated with nylon closures was intermediate between staple and silk closures. At no time was nylon collagen production as mature as that associated with staple closures. Nylon collagen levels were always greater than the silk levels (Fig. 2). Bronchial stump leakage pressures correlated closely with the above described histological evaluation. Twenty-four hours postpneumonectomy, there was no significant difference between the average leakage pressures of four staple and five silk closed stumps (Fig. 3). However, at three days a marked difference in leakage pressures became apparent. The average leakage pressure of the five staple closed stumps (117.42 mm Hg + 66.6 SD) was significantly greater (p < .05) than the average leakage pressure (54.80 mm Hg ± 14.5 SD) of the five silk closures.

JANUARY, 1976

(139.4 mm Hg + 26.3 SD) (Fig. 3). Similar to the histological pattern described earlier, the leakage pressures associated with nylon closures were all intermediate between silk and staple closures. Staple closures were always stronger than nylon, and silk closures were always weaker than nylon. 350

300

EE

250 200-

A-

150-

A serial comparison of bronchial stump closure techniques following pneumonectomy.

42 JOURNAL OF THE NATIONAL MEDICAL ASSOCIATION JANUARY, 1976 A Serial Comparison of Bronchial Stump Closure Techniques Following Pneumonectomy* RIC...
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