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The long-term physiological effects of lung reimplantation in the dog
Jo
al of
cal R se
Clinical and Laborato~q Investigation Volume 6 Number 5, May 1966
THE
LONG-TERM PH.YS!OLOGICAL EFFECTS REIMPLANTATION IN TItE DOG I1OBGRT
MARSIIALL~
M
D*,
T H E aim of hmg transplantation is to provide a h m g that will continue to hmctiou well for many years. In the operation of transplantation the 'continuity of tim bronchi and puhnonary w~ssels is restored but the bronddal vessels, nerves, and lymphatics are completely severed. It is possible that these stn lctures play }ome part in maintaining tile normal function o~ the lung [3]. Since the immunological diNeulties have not been e in homologous lung4ransplantation, a study has been m a d e in dogs to determine the long-term ftmetion of the hmgs after reimplantation. Most of t h e studies have been made on 3 dogs whielr have'been observed for periods of a N years, g ~ 2 years, and 2~/., years, respectively, after reimplautation of the left hmg. In 2 of the dogs the puhnonary cireulation does not appear m have been completely restored after reimplantation of the lung, but these dogs still serve to slmw the progress of hmg hmctiOn after operation.
METH
ODS'
Reimplantation In all dogs the left h m g was rdimplanted by a method similar to that of BiJeherl et aL [4]. From the Nuflield Dci)artment of Surgery, Radcliffe Iufirmhry, Oxford, England. Th~ inv~tigatior~ was supl~rt~], in part, by a grant from the Medical "Research Council Submitted fdr publication*Sept, 27, 1965.
AND
A,
J.
OF LUNG
GUNNING~
After e_xeision of the hmg, the vessels were washed through with hcparinizcd saline sotu/ion and the hilar structnrcs sutured in the order atrial 'cuff, bronchus, and p u h n o n m y artery. The eirctdation to the hmg was. inter.up to 2 hours. After-rehmg vessels and bronchi, the hmg was recxpanded by positive pressure and the elmst wall closed around two drains. which were connected to. a" water-seal bottle for a few hours, then clamped, and finally removed after about ~ hours.
Lung Fmwtion 7~sts Measurements of functional residual capacity, diffusing eapacity,-0xygen uptake, and pulmonary stretch reflex~.v; before reimplm,tatio~ and a~ in ~rward. Bronchospi~:om(3try ~,,as carried out" using the tube described previously [27]. The" m e t h o d s used were as:f011ows. Tliis was F U N C T I O N A L I I ~ I I ) U A L C A ! ,A C I T Y . measured by t h e closed-circfiit helium tebhniquc. Measurement was m a d e first on both hmgs a cuffed endotraeheal .tube and then. insertion of a bronehospirometry tube, on each h m g consecutively. DIFFUSING CAI AClTY
F O Il C h l t ~ N
~ I O . OXIDE,
The measurements .lungs combined, b) method described pre~ously [27]. ox~ each eters 185
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and soda-lime cannisters. Measurements were • inade with a high oxygen concentration in each g'pirometer. PUL~[ONARY S'I]~ETCII REFLEXES. The stretch reflexes from each lung were tested a t bronchospirometry by inflating one lung with a pressure of 10 or 20 era. HeO. While inflation was maintained in this lung, the other lung was free to breathe from the spirometer system.
The Mechanical Properties of the L~lgs TIDAL VOLtn,~E. The md~lanical properties of tile two lungs are compared most readily by recording the tidal volume of each lun~ on the X and Y axes; respectively, of a cathc.~de ray oscilloscope [27]. The volume recordings were made'using low-torque pote~itiometers which were rotated.either by the strings of the.normal spirometers or by a pair of low-inertia wedge spirometers. If the nonelastic resistance o f each lung, relative to the tidal volume, is the same for the two h a g s , the tracing will move u p and down a straight line, and the slope of the li~ie is a measure of the relative c~;mpliance of the two lungs, In this situation the time constants of the two lungs are the same [29]. If the time constants are unequal, the tracing will describe a loop; the lung widl the smallest time constant (smallest nonelastic resistance relative to its compliance) will fill more rapidly at the start of inspiration and empty more rapidly at the start Of expiration. In none of the dogs were the time constantsso different that, during normal respiration, one lung bad begun to empty before the other nile had filled completely. ~ e ratio of tidal volumes of the two lungs v~as therefore a measure of the relative compliance" of itlae two lungs. In addition, simultaneous pressure-volume loops of each lung were recorded on a doublebeam cathode ray oseilloscope by applying a pressure signal, obtained from an intraesophageal balloon, to ~the ~." axis of the oscilloscope and the volume signals from the lungs, one to each beam, on tlle Y axis of tlie oscilloscope, UNIFOR~.ilTY OF VENTiIa~TION. ~ae nitrogen wasl~out 0f file lungs w a s meas~_~red by monitoring the expired nitrogen while the dog was ~6
q)reathing 100% oxygen, A comparative measure of the nitrogen washout in each hmg was obtained by sampling from each side.of th( ~ bronchospirometry tube in turn for four or five breaths while the dog x~;~as breathing I007~ oxygen. Another metl/od used to test tile uniformity of ventilation was suggested by Dr. Jere :\*lead (personal communication). Tlle dog was enclosed in a body plethysmograph, with breathing nlaintained through a cuffed endotracheal tube to the outside of th%plethysmograph. The airflow from the hmgs was measured by a pneumotachygraph On the plethysmograph and the outpu t was integrated to measure the volume expired. Flow was recorded on the Y axis and volume on the X axis of a cathode ray oscilloscope. A 10 liter aspirator bottle was evacuated to a pressure of ~200 nam. Hg, connected through to the endotracheal tube, and the curve of flow rate and lung volume recorded as the dog's lungs were collapsed. "~qth short rest periods between, the hmgs were emptied at slower, uniform rates by sucking out the lungs with a large piston punap. It has been shown (by Dr. :'dead) that, in normal lungs, when the n~aximum flow ~ t e falls at small lung volumes, the curves are superimposed whatever the initial rate of lung emptying. When lung emptying is not uniform, tile flow rates that can be attained at small hmg voh, mes are higher When the lung is emptied slowly and uniformly than when it is emptied rapidly with a powerful suction. DuS~rlNGOF "rile LUNG. An club: for, as described b y DuBois and Dautrebande [8], was used to produce a cloud of fine charcoal particles. Before a n d after inhalation of the particles into one of t_lae lungs, recordings of the tidal volumes of each hmg on coordinateaxes were made as described above. After an interval, recordings were made before and after inhalation into the other lung. Ten to 30 breaths of dust were taken into each qung, b rond~oscopy afterward showed a coating of dust i~x the bronchi. AEnOSOLINHALATION. A sol,.ltion of 3~/b histamine acid phosphate was nebulized in a DeVilbiss No. 40 nebulizer and the aerosol inhaled into each lung in'tt~rfi. Coordinate re-
XiAIISIIAIA. AND ( ; U N N I N G :
LONG-'YEI~,N! E F F E C T S
cordings of tidal volume were made before and after each inhalation.. 19 some experiments[ similar recordings were made after the inhalation of isoprenalinc aerosol. CILI:AItY ACHON. An attempt was first made to measure ciliary activity by placing, in one 6f the peripheral bronchi, a small deposit of radioactive gold adsorbed on to charcoal particle-s. The radioaet!vity along the bronchus was eotmted with the use of a collimated scintillation counter. The deposit of radioactive material could be located, but it did not move over a period of several hours, possibly because of the eft'oct of radiation on the cilia. Some estimate of eilia~, activity was obtained by placing a small deposit of India ink, adjusted to a pH of 7.5, down each bronchus and observing the rate of movement up each bronchus. coven m~:VL~<. The cough reflex was in. vestigated during I)ronehoseopy by touching the brcmehial m u c o s a with a probe. The response to chemical stimuli was tested by allowing the dog to l)reathe an aerosol of 2 5 ~ citric acid down each side of the bronchospirometry tube in turn. Anesthesia The measurements of hmg volumes mad diffusing capacity and the bronchospirometry were made after the dogs had been premeditated with too@line and ehlorpromazine and anesthetized with pentobarbital. The investigation of cough reflexes, reflexes to dusting, and ciliary action was carried out under vew light pentd)arbital anesthesia and also under ehloralose anesthesia.
RESULTS
Lung Function I'ULN[ONARY S~rltErCH I~EFLE~I:~. ~le H e r ing-Breuer stretch reflex, as reported by others [31], was absent in the rNmplanted hmg when tested a few months after operation. Inflation of the fight lung t o a pressure of 20 em. H~O produced an apnea lasting for 1 minute or more, but inflation of the left hmg had ahnost no effect on respimto W xhythm
"
~
OF
LUNG I I E I , M P L A N T A T I O N
.20 cmfH~O i lift.
~ g
tEFr
.
.
i
IN T I I E I)OC
:
..........
B
Fig. I. The effect of unilateral hmg inflation on the respirato W rhythm. (A) Dog 3, 2.',4 years after reimphmtation of the left lung[ (B) Dog 1, 3 ~ years after reimphmtation of the left lung.
(Fig. 1A). [n Dog 1, when tested 33-~ years after reimplantation of the left hmg, the Hering-Breuer r,Atex appears to be returning (Fig. IB): Inflation of the left hmg to a pressure of 20 cm. of water caused the interval between breaths to increase to almost four times that before inflation, whereas, 6 months previously, inflation of t h e l e f t lung h a d had Ve~ little effect on respiratory rhythm. Deflation reflexes Were also )nvestigated by applying a negative pressure to each lung in turn, but deflation ~ of one hmg inflated the other and made it impossible to assess the resuits. LV~-~C S~JZ. The funetionaI residual capacity of the two lungs, measured together and of each lung separately, is shown inFigure 2. LUNGCOZ-II'LIANCE. The relative compliance of t h e two lungs is indicated by t h e tidal volume of the left-lung, expressed as a percentage of the total tidal volmne (Fig. 3). A measure of the distei~sibility of the lungs which takes into account the Change in volume of the 187
J O U R N A L OF SUllCtCAL ]~ESEAItCII
VOL. 6 No. 5, ~XIAY ~966
DOG !
/
-
6"
~a0
V 4~
u: "'~,r,"'D06 ,30"
i veA~s AFTe~ ~E~MPLA~TAT~ON OF t e F T LUNQ
Fig. 4. The ratio of tidal w~lume to functional re,dual capacity (F.R.C.) of each hmg, measured before and at i,{tervals after reimplantation of the left Irreg.
oze. / \t
Fig. 2. The fnnctional residual capacity of tlae hmgs measured before and at intervals after reimplantation of the left lung. R = right lung, L = felt lung, R + L = l~th lungs measured together. 501
°1
the results of nitrogen washout measurements on the hmgs. These washout times did not differ appreciably from those of a control dog. In Dog 3 the left lung washed out more quickly than the right, blot the ventilation per unit of lung volume was much greater on the left thau o , the right. Curw~s of fJov., rate related to lung volume, obtained as described above, did not sho;,v, in any of the ~,,.gs, ;:~' that flow rates which could be achieved at low lung volumes were higher after the lungs had been emptied slowly than they were after r~nid emptying, q~aus this test did not show any evidence of unequal emptying of the lungs. . L ~ W A Y nESZSTANCE. An example of the recording of the tidal volume of the two lungs on coordinate axes is shown in Figure 5. In all TIOAL VOLUME
YEARS AFTER REIHPLANTATtON OF LEFT LUNG
Fig. 3. The ~dal volume of the left lung, expressed:as a percentage of the total tidal Volume, measured before and at intervals after reimp]antation of the left lung. hmg, is obtained by comparing the tidal volumes 'per 1 ~ ml.-0f: fu~ctionaI residual capacity. This is a measure of the specific cornpliance of the lung. Figure 4 shows the ratio of the s p e c i e compliance of t h e ~ght and left lungs. IJN'I~OR~-T'x" O F " ~ N q ~ T Z O r ¢ . Table 1 shows ~88
/;
RIGHT LUNG /
* 3 ¢
e .//';, f00 Hr. 4~*
|OO
TIDAL
VOLUHE
00(3 2
ML,
*LEFT~LUNG
Fig. 5. Tracings obtained by ooordinate recording Of tidal volume at bronchoscopy. For explanation see text.
.~IAI1SItALL ANI) G U N N I N G :
Table 1.
Dog No. 1
:~ 3
Both Lungs Years Time to After 2% Ne No. of Relmplant. (rain.) t~c.aths 3~ 7 23 2½ 5½ 32 2½ 7¼ 21
LONG-TEE.%I E F F E C T S
Dog No. 1 2
IIEI~IPLANTATION
IN T H E
Nitrogen Washout o[ the Lungs Tidal Vol,/100 ml. F.R.C. (ml.) Right Lung
Left Lung
30,0 31.8 ~,8
37,3 29.9 36,8
3 dogs, before reimplantation of the left hmg, file record during inspiration and expiration was a straight line, as shown for Dog 1 irl Figure 5. The record for Dog 1 remained a straight line after reimplantation, but the tracings for Dogs 2 and 3 became ~ anticlockwise loop with most deviation from the straight line on expiration (arrow pointing down, Figure 5). This ~implies that the time constants of the two hmgs are similar on inspiration b u t that the time constant of the left lung is shorter than that of the right on expination. cough ~mI-'LEXES. The cough reflex was investigated both under very light pentobarbital and under ehloralose anesthesia. Touching the larynx or lnovement of the bronehoscope in the larynx caused coughing: but mechanical stimulation of the bronchi below the carina or an aerosol of 25ct~ citric acid breathed through each side of tile bronchospirometry tube in turn did not cause coughing. RI:;FLEX B R O S C I t O C O N S T R I C T I O N , Inhalation of charcoal dust into each lung in turn, with'coordinate re~qrding of the tidal volumes, caused no change in the relative time constants of the two hmgs; neither was there any change in the relative compliance of the two lungs. Inhalation of histamine aerosol in the two Tal~le 2.
OF LUNG
Right Lung Time to 2% Nz No, of ( min.) Breaths 7 4 5)/2
23 31 32
Left Lung Time to 2% N~ No. of (rain.) Breaths 7 over 7 3
over 40 20
dogs ill which it was used caused a decrease in compliance in tile lUng which inhaled the aerosol. Tile results are shown in Table 2. Tile response of the left hlng was approximately equal to ~that of the right, Histamine did not change the shape of the loop obtained by coordinate recording~that is, it did not change the time constant of the lungs, Any change in nonelastic resistance was equal and opposite to the change in compliance. This effect w o u l d be produced if t h e histamine caused terminal airway closure rather than narrowing of the airvcays. OXYGEr: m'Tar:E. The percentage oxygen uptake of file left lung is shown in Figure 6. The value of 50% obtained for Dog 1 before operation is higher than float usually found in normal dogs and the postoperative valu~ of about 40% are in the normal range for the left lung. There has been no tendency for the oxygen uptake of the left lung to f aU with the passage of time. It is most probable that some vascular damage was produ-ced in Dogs 2 and 3 a t the time of operation and that this is the reason for the l o w ~values for the oxygen uptake of the left lung obtained postoperatively; there has been no further deterioration in Dog 2 a n d some recovery of function in Dog 3.
Effect of Histamine Aerosol on Lung Compliance and Tidal Volume
Control 34.7 31.7
Percentage of Tidal Volumeon Left Histamine: Histamine: Right Lung Control ~ f t Lung 40:7 36.6 32,5 34.2 31.7 27.8
Percentage Change in Compliance After Histamine Right Lung Left Lung ~22 --19 --11 ~16 ~89
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figures can be given for the ciliary activity of the right and left main-stem bronchi. In 2 of the dogs, however, the India ink injected, into the bronchi traveled up comparable lengths of the right and left main-stem bronchi to the carina in the same time. In the other dog the rate of movement on the left side was only about one.third that on the right.
Ilistological Findings
o
Fig. 6. The oxygen uptake of the left hmg, expressed as a percentage of the total uptake, measured before and at intervals after reimplantation of the left lung. ~ e measurements of oxygen uptake were made with the dogs breathing a high oxygen concentration from each of the spirometers. Under these conditions the blood leaving each lung is fully saturated with oxygen, and since the inixed venous blood entering eac4a lung has the same oxygen content, the a~eriovenous oxygen difference o f each lung will be the same, The ox),gen uptake of each hmg is therefore proportional to the blood flow through each lung. ~IE
DIFFUSING
C~PACITY
FOil CAllllO:'4 ~[ONOX-
row. The°results of measurements of the diffusing capacity of both lungs for CO are shown in Figure 7. cILIAmt" Ac':~w~r~". No precise quantitative ttl
a
x O
g
B2-
It "x"
YEARS AFTER REIIHPLANTAT!ON~
tEFT tUN6
Fig. 7. The diffusing capacity of the lungs for carbon monoxide, measurecl before and at intervals after ieimplantation of the left lung. ~9o
Dog 1 died of pneumonia a few days after the final measurements reported here were m a d c ~ t h a t is, 3:~{ years after reimplantalion of the left lung. At autopsy hoth hmgs showed patd~y consolidatign, rather more on the right side than the left, but the left lung had no adhesions arid otherwise appeared normal. The lungs were inflated with formol saline and allowed to fix. q'be puhnonaD, artery suture line was almost invisible, and tile suture line and the main branches of tile arte W showed no evidence of thrombosis. Similarly, the suture line in the left atrium was also clean, and all the main pulmonary veins w e r e patent: The bronchus had healed well, with only a small crescent of mucosa pulled into the lumen on the medial wall. Blocks of tissue were taken for histological examination from above the bronchial suture line, across the suture line, at 1, 3, and 5 era. below the suture line, and from the periphery of the lung. Blocks were also taken across the atrial and pulmonary artery suture lines, and from the right lung for purposes of comparison. The sections were stained with hematoxylin and eosin and with Hohnes's stain for nerve fibers. The small bro~ehial arteries in the sections were not appreciably different in the two brags, and no evidmace was found of fl~rombosed or obliterated arteries. There was considerable peribronchial and periarterial edema in bofl:t hmgs, presumably the result of the pneumonia. In the left lung, lmndles of nerve fibers were found in branches of'the bronchi down to 1.5 ram. diameter. F a i l u r e to field them in branches smaller than this was probably due m inadequacy of tlle staining technique; Some of the nerve brandies were within sheatlis, but around oth6rg ~o sheaths were
51IARSIi[ALL AND G U N N I N G :
LONG-q['EtlNI E F F E C T S
evident. "/Tie number of nerve bundles was approximately file same in the left as in the right hmg. Peribronehial ganglia were not seen in any of the sections taken from below the suture line.
DISCUSSION
The purpose of this study was to investigate tile changes in hmg function, particularly long-term changes, which might occur in lungs that have no bronchial arterial or nerve supply. Although many experimental animals have a well-marked stretch reflex from the hmgs [36], the role of stretch reflexes in man is still under inves6gatiom Widdicombe [35] showed that man has only a w,'eak HeringBrcuer reflex. Recent experiments involving Mocking of both vagi in man [15] show that the vagi are not essential for maintenance of a nonfiaI respiratory rhythm although vagal block does appear to allow some prolongation of breath-holding time. In hmg reimplantation or transplantation all the nerves {o and from the lung are severed, and this may have a greater influence d~an vagal section only. Several worl-:e~ have reimplanted one lung and, at a later date, removed the other [i, g, 10, 13, 17, 19, 23, 37]. In some of file animals, respiration became slower and irregular after removal of the normal hmg [I,'~, 19, 23], but in others no abnormality was reported. Most of the animals subjected to pneumonecton@ of the normal lung started spontaneous breathing after operation. ~ l e respiratory paralysis fllat Howard and "~Vebb [20] found after total denereation of the lungs has been attributed to damage to tile phrenie nerves [13]; however, respiratory para}ysis was usually associated with high denervation of the trachea, and it is possible thae receptors in the trachea and larynx may be suflqcient in some anfinals for the maintenance of rhythmic respiration. The cause of death after pneurnonectomy in many of the animals, as also in those after occlusion of t!-.e contralateral pulmonary artery, is pulmonary edema caused by the high
OF
LU N G
REINIPLANTATION
IN T I l E
I~G
pulmonary arterial pressure [4, 6, 18]. Duvoisin et al. [10] suggest that the cause of det~tb in their own series, and in those reported by others, was due to damage in tile reimplanted lung. A normal dog can exist oll only ~ % of its puhnonary vascular bed [16] so that if death is due to.puhnonary insufficiency the denervation of the hmg, or al}sence of the hronddal arterial supply, may play a part in causing death; however, as discussed below, no evidence was found that rei|nplant~rtion 1-ms any effect on the tone of the p u l m o n a ~ vessels. In studies which have been reported previously, no evidence of a return of the IleringBreuer reflex has been found, Portin et aL [31] found that the Hering-Breuer reflex was s~lI absent in a dog 35 months after reimplantation of tim lung although in the dog at autopsy numerous nerve fibers were found below the suture line in both the pnhnonary artery and the bronchus. The retunl of the Hering-Breuer reflex in Dog I, .3~/~ years after reimplantation, appears to be the first instance reported of restoration of the reflex. In this dog, too, nerve trunks were found in the peribronehial tissues. If st retd~ reflexes are essential for normal function of the lungs, fllen regeneration of the puImona W nerves may be important in patients in Mmm hmg transplantation is carried out and who may require eontralateral pneumoneetomy at a later date. In these (togs eMdence was sought for the presence of reflexes other than the stretch reflex. The cough reflex might be important in preventing infection in the lung, although a cough is probably concerned mairJy with clearance of the trachea and main bronchi raffler tllan of the smaller'bronchi [26]. If bronchial secretions .are present on the normal side, or if secreOons on the reimplan~d side are moved as far as the c a n n a by ciliaW action, any cough induced will be equally effective on both lungs. The lower airways of a dog are noted for their insensitivity to ~ e cough reflex, and in the dogs studied here, in spite of the very light anesthesia and a sensitive IaryngeM reflex, no reflex could be obtained from the lower airways. The inhalation . of ~dust has been reported 191
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to cause an increase in airway resistance due to a nervous reflex from the bronchi [36]. In these dogs. no bronchoconstrietor effect was found, either in the normal or in the reimplanted lung. This could be due to insensitivity in the method used, but the method would llave detected a change of the order found by Widdieombe et aL [36]. Another reason for the absence of reflex could be that the receptors are mainly in the upper trachea. It has been suggested that emphysema is more liable to develop in reimplanted h.mgs than normal hmgs. This could happen if loss of the nerve supply to the hmg resulted in bronehiolar eonstricti0n or if the ,absence of a bronchial blood supply caused irnpairment of the elasticity of the hmg tissue [7]. One di~culty in following dogs such as these over a period of years is that the dogs' ages are unknown, and it is often difficult to be certain of their maturity. ~ m s 2 of the dogs studied, and also 1 control dog, wllich was studied over a period o~ 2 years, showed an increase in the hmctional residual capacity of the lungs v,,hieh was probably related to maturity rather t h a n ' t o the development of emphysema, although marginal emphysema is not uncommon in dogs. During the period of observation the weight of Dog 1 increased from 15.0 to 16.0 kg., that of Dog 2 from I5.0 to 16.4kg., and that of Dog 3 from 15.9 to 20.0 kg. ~ e increase in the size of the hmgs in Dog 3 has resulted from increase in the volume of the right hmg rather than that of the left, but damage to the pulmonary circulation may be responsible for the failure of the left lung to grow. The changes in lung volume found at the final measurements in Dog 1 m a y b e due to the development of pneumonia from which this dog died 3 days later. The relative eomplianee of the two lungs (Fig. 3) does not change appreciably over the.years. In view of the changes in lung size, the specific compliance of the hmgs (compliance per unit vo]nme of lung) is a better indication of any change in lung elasticity Milch may have taken place. T]~e specific compliance of the left lung, relative to that of the right (Fig. 4), tended to fall over the years in Dogs 1 and 2, but in Dog 3 there :t9e
was no significant change from the rather low vMue immediately after operation, ~-m change in specific compliance of the hmgs at the end of the period of observation, compared with thc values before operation, were for Dog l, right lung - - 1 9 ~ , left hmg --7'~;, Dog 2, right lung -[-20~, left hmg + g6¢fi, and Dog 3, right lur, g -- 16%, left hmg + 33~?;. These figures, taken in conjunction with those for changes in lu,ig voh, me, do not indicate any tendency for the reimplanted hmg to become more distensible or more fibrosed than the normal lung. The measurements of the time constants of the two hmgs also indicate that the time constant of the reimplanted hmg is not incrc
.~IAIISItALL AND C U N N | N G :
LONG-TEIt~I
corded by, bronehospirometry. In none of the dogs did the relative oxygen uptake of the hmgs change during infllsion, as would be expected if the pulmona W vessels in the reimplanted hmg were snlqeet to vasoconstriction thaicould be relieved by aeetyleholine. A deerease in the relative blood flow through a reimplanted hmg is more likely to be due to vascular thrombosis following operation than to active vasoconstriction. q>n months after reimplantation of the hnlg in Dog 1 measnrements were made of differential hmg blood flmv during the breathing of anoxic gas mixtures by each of the lungs in turn. Anoxia of ei0mr hmg caused a shift of blood flow to the other lung. TMs response to anoxia wmdd be expected to occur since it also happens in the isolated perfused lung [91.
The total diffusing capacity of the hmgs for carbon monoxide in the dogs remained unehange~t or even increased after reimplantation, This does not indicate that the dog still has a good diffusing capacity in the reimplanted lung. q31e diffusing capacity, remained unchanged after reimplantation in another dog which was later discovered to have a completely fil)rosed Ieft hmg. In some species the cilia are partly under the control of the nervous system. The piflatal cilia of the frog are normally immobile but may be made to beat by neural stimulation [25]. The cilia of vertebrates beat continuously, even in tissue culture [32]. Direct observation of the cilia in the duck and turtle [ ~ ] failed to show that the rate of beat was influenced by nerve stimulation. Shmagina [33] showed, however, that a small load placed on the tracheal cilia of the dog or cat was moved more rapidly when the vagus was stimulated and more slowly when the sympathetic nerw~s were stimulated. The evidence for direct nervous control of the cilia is not supported by anatomical studies for neither in the dog, rabbit, nor man has any nerve supply been foufid to die cilia [11, 21, 22, 34]. The efferent nerves to the bronchi all end in the smooth muscle or around the brondlial glands. Pi6ron [30] and also Gordonoff [14] have suggested that nerves may, have an in-
EFFECTS
OP" LUNG
ItEI.~II'LANTATION
IN T I l E
I)OG,
direct action on cilia W activity by dmnging the composition of the liquid layer in whicli the cilia work. The ciliary activity in the lungs of these dogs measured, 2 to 3 years after reimplant;3tion, was not obviously decreased, and there is no reason to suppose that a reimplanted or transplanted hmg is more liable to retain secretions than a normal lung. It is of interest that when Dog 1 died of pneumonia, the right. hmg was affected more severely than the left. The lymphatic vessels are also divided at the time of reimplantation of the hmg. Although Nigro et aL [~S] reported dilated lymphatic channels in the re.implanted lung several months after operation, Eraslm{et aL [12] have shown that mlmerous lymphatic vessels cross the suture line by 30 days after operation. qqm reimplanted hmgs of these dogs were not clinically edematous and the compliance was not reduced so there is no evidence of significant lymphatic ohstruetion in the reimplanted hmg. The eNeiency of the lymphatic circulation, however, may be an importm~t factor if the other lung is removed; total pneumonectomy may cause the pulmonary arterial pressure to rise and ilierea:se the exudation of fluid into the reimplanted lung.
CONCLUSIONS
II~ese experimene~ on reimplantatimi of the lung in normal dogs indicate that the hmg may function normally for many years and may even regain its stretch reflex. Transplantation of the hmg in.man, .however, may iiitroduee long-term complications oflmr than those due to immunological di~eulties. A lung, or a lobe, will probably be transplanted most commonly in patients in whom the re~ maining lung is eidmr fibrosed or emphysematous. If the remaining hmg is fibrosed, the presence of an adequate amom~t o f normal (transplanted) hmg in the thorr~ will mean that the stiffer, fibrosed lung will expand very little during inspiration, al!d it wi!l probably undergo a progressive contraction. This may have two disadvantages: first, the con59a
J O U I t N A L OF SUItGICAL llESGAIIClI
YOL. 6 NO. S~ ;NIAY
tracted inactive lung will provide a site for bronchial infection; and second, if the h m g contracts down completely, there is the danger that stretch 'reflexes will not be stimulated. ~-~e stretch reflexes, however, may not be essential for normal respirat!0n, If transplantation of the h m g is done for emph'ysema, tim remaining em.physematous h m g will probabl>; remain distended and take v e w little part in gas exchange. On inspiration th'e transplanted lung will distend more easily, a n d on expiration it will empty before the emphysematous hmg. Again there is the possibility of inadequate stretch reflex activity. A n o t h e r possible d a n g e r is that the ernl£hysematous h m g will continuQ to expand and compress the transplaot, in much the same way that solit~ry lung cysts can expand and compress normal lung tissue. This might happen in patients with primary emphysema raffler than in those with emphysenaa secondary to chronic bronchitis. A transplanted lobe w o u l d be m o r e ' v u l n e r a b l e than if a whole lung were transplanted. SUMMARY Physiological measurements of h m g function, including bronehospirometrie measurerncnts, have been m a d e on 3 dogs for up to 33,~ years after reimplantation of the left iung. T h e r e is no evidence that the reimplanted l u n g degenerates more rapidly than the norreal lung. T h e hmg does not show any evid e n c e either of fibrosis or of over distention, and the airway resistance is commensurate with h m g size. c i l i a w activity is also normal in .the reimplanted~ lung. The blood flow thr.gugh t h e reimplanted Itmg is nomla] unles~ vascular obstruction, o c curs at the time of operation. No evidence of vasoconstriction was found in the reimplanted lung. ~ l e lung stretch reflexes are absent initially b u t s h o w evidence of r e g e n e r a t i o n after several years; Other reflexes f r o m the bronchi, such as the cough reflex and bronclaoeonstrietor.reflexes, were looked for but were not demonsti'ated in effher hmg. 194
1966 REFERENCES
i. Alican, F,, and Hardy, J. D. Lung reimplantation: Effect on respiratory pattern mad function. J.A.M.A. 183:147, 1963. 2. Blumenstock, D. A., Collins, J, A., Ilcd~tman, H. B., qqmmas, E.'D,, and Ferfel)ce, J. W. Functioning homografts of the lung in dogs. Ann. N,1L Acad, ScL 99:882, 1962~ 3. Bogardns, G; M. Evaluation in dogs of |he relationship of pulmonary brond~ial and hilar adventitial circulation Io the problem of hmg tmnsplantatlou. Surgery 43:849, 1958. 4. BiJcherl, E. S., Leseh, P., Nasseri, M,, and Prondz)~ski, B. V, L~mgenfnnctionsstudien naeh Homo- ut~d Autotransplantation bzw. Denervation der linken Lunge und hnschliesscnder Unterbindung der rechten Pulmonalartcrie. Thorax. chlr~trgie 11:540, 1964~ g. Biicherl, E. S., Lesch, P., Nasseri, M., and l~ichter, M. Ergebnisse experlmentelle Untersnelmngen naeh uonnoflmrTner nnd hypothermer Homotransplantation der Lunge. Arch. Kll,~. Chit, 296: 660, 1961. 6. Christiansen, K. II., Buck, A. S., Fanfera, F., Gross, R., Pind~, L. "W,, Stainback, \V. C., and Trummer, M. J. tlomologous transplantation of canine lungs. Arch. Surg. 90:38, 1965~ 7. Cudkowicz, L., and Armstrong, J. B. The bronchial arteries in p~,lmonary emphysema. Thorax 8:46, 1953. 8. DuBois, A, B. and Dautrebandc L. Acute effects of breathing inert dust particles and of carbachol aerosol on tim med~anieal characteristics of the hmgs in man: Changes in r~sponse after Y'qmlingsympathornimetic aerosols. 3. Clin. lnvest. 37:1746, I958. 9. Duke, H. N. Puhnonary vas~mmtor responses of isolated perh~sed cat hmgs to anoxia and hypercapnia. Qttart. ]. Exp. PhysioL 36:75, 195t. 10. Duvoisin, G. E., Fowler, W. S., Payne, \V, S., and Ellis, F, H. Reimplantation of the dog lung with survival after cont~dateral pnemnoneetomy. Surg. Forun~ 15:I73, 1964. 11. Engstr6m, H. The structure and innervation of the tracheobronehial--,all. Bronches 3:327, 1953. 12. Eraslan, S., Turner, M. D., and Hardy, J. D. Lymphatic regeneration following lung reimplantation in dogs. St*rgend 56:970, 1964. 13, Faber, L. P., and Beattie, E, J. Respiration following lung dener'¢ation.. Surg, Forum 9:383, 1959. I4. Gordonolf, T. Physiologie und Pha~akologie des Expectorattonsvorgang~. Ergebn. Physiol. 40:53, 1938. 15. Guz, A., Noble, M. L M., Ve'iddicombe, J. G.. Trcnchard, D., Mushin, VC W.," and Makey, A.R. The role of vagal.and glossopharyngeaI afferent nerves in respiratory sensation, control
X I A I / S I | A L L AND G U N N I N G :
16.
17.
tS.
19.
fi0. 21. 22. 23. 24.
25.
26.
LONG-TER~I
of breathhlg and arterial press~Ire regulation in conscioHs man. Cltn. ScL 30:161, 1966. H~ggart, G. IL, and VrMkcr, A.M. The physiology of pulmonary embolism as disclosed by quantit;~llive occlusion Of the pulmonary artery. Arch. Surg. 6:764, 1923. tlaglin, J., Telander, R. L , Muzzall, 1t. IL, Kiser, I. C,, and Strobel, C. J. Comparison of hmg antotransphmtation h~ the primate and dog. Surg. Forum 1:4:I96, 1963. Hardy, J. D., Enlshm, S., and Dalton, M. L A~totransplantation mad homotrm~sphmtati(m of the lung: Further stmlies. 1. 77~orae. Cardiov. Surl2. 46:{R)13, 1963. t'lanty, J. I)., Erashm, S., Dalton, M. L,, Alican, F., and Tunmr, M. 1). Rcimplantatirm and homotran~plantation nf the hmg. Ann. Surg. ]57: 707, 1963. l loward, I1. S., and Vrel)I), W. I1.. Respiratory paralysis folh)wing pulmonary denervation. Surg, Form~ 8:466, 1958. l,arselL O. Nerve tenr~inations in the hmg of the rab|dt. J. Comp. Neuu~L 33:105, 15)2I. Larsell, O., and l)ow, IL S. The inner,,ation (ff the human Im|g. Amer. J. Anal. 52:125, 1933. IAnberg, E. J, DemetHadcs, A., Am~strong, 1L V¢., and Konsuwan, 11. Lung reimphmtation it~ the dog. J,A.M.A. 178:486, 1961. Lueas, A. M., aml Douglas, L. C. Principles underlying cilia D, activity in the respiratoD, tract: III. Independence of tracheal cilia in vivo of drag and nenrogenous stimuli. Arch. Otolaryng. 21:285, 1935. Mcl)ona]d, J, F., Leism:e, C. E., and Lenneman, E. E. Neural and chemical control of ciliated epithelimn. Proc. Soe. Exp. Biol. Med. 24:968, 1927, Marshall, 1t., and Holdeu, ~,V, S. Chmlges in calibze of the smaller ai~vays i~ mmL Thorax 18:o4, 1983.
EFFEC'IS
OF
LUNG
IIEINII~LANTATION
IN T I | E
DOG
27. Marshall, R., Sabiston, D. C , Allison, P. R., l~)sman, A, It., and Dunnill, M. S. Immediat~ and late effects of pulmonary cmboli~n by lhrge thmnflfi in dogs. Thorax 18:1, 1963. 28. Nigm, S. L., Evans, IL H., Benfield, J, It., Gago, O., Fry, W. A., and Adams, "-,V. E. Physiologic alterations of cardiopnlmonary function in dogs living one and one-half years on only a reimphmted right hmg. J, 7Vmmc. Cardiov. Surg. 46: 598, 1983. 29. Otis, A. B, MeKerrow, C. B., Bartlett, R. A., Mead, J., Mellroy, ~M. B., Selverstone, N. J., and lladford, E. P. Mt~:hanicaI factors ia~; distribution of pulmonary ventilation. J. "AppL Physiol. 8:427, 1956. 30. Pi6mn, 1t. S|ructure et fonctions de l'epithdlimn de revt, tement des c~nduits respiratoires, J. Franc~ Med. Clair. Thorac. 15:177, 1961. 3I. Porlin, B, A., Rasmussen, G. L , Stewart, J. D., am] Anderson, M. N. "PhysiNogic and anatomic stmlies thirty-~ve months after suecessNl reimplantafion of lung. J. Thomc. CaMiov. Su N. 39:380, 1960. 32. Rose, J. M,, Pomerat, C, M,, and Danes, B. Tissue cMture studies of ciliated nasal mncosa in man. Anat. Reco~l 104:409, 1949. 33. Shmagina, A. O. Nervous control of ciliary movement. Bull. Biol. Med.'Exp. URSS (Moscow) 1:418, 19362 3,t. Spencer, H., and Leof, D. The innervation ot the human hmg. J. Anal. 98:599, 1964. 35. "~Viddieombe, J. G. lte~pirato~ reflexes in man and other rnam'tnalial species, Clh~, ScL 21:1.63, 1961. 36. \Viddieombe, J. G,, Kent, D. C., and Nadd, J . A . Med~antsm of bronchoeonstriction during inhalation of dust. J, Appl. Physiol. 17~613, 1962. 37. Yeh', T, J,, Ellison, L T., and Ellison, R. G. Functional evaluation of the autotranspIanted h!ng in Om dog, Amer. Bee. Resp. Dis. 86:791, 19132.
195
al of
cal R se
Clinical and Laborato~q Investigation Volume 6 Number 5, May 1966
THE
LONG-TERM PH.YS!OLOGICAL EFFECTS REIMPLANTATION IN TItE DOG I1OBGRT
MARSIIALL~
M
D*,
T H E aim of hmg transplantation is to provide a h m g that will continue to hmctiou well for many years. In the operation of transplantation the 'continuity of tim bronchi and puhnonary w~ssels is restored but the bronddal vessels, nerves, and lymphatics are completely severed. It is possible that these stn lctures play }ome part in maintaining tile normal function o~ the lung [3]. Since the immunological diNeulties have not been e in homologous lung4ransplantation, a study has been m a d e in dogs to determine the long-term ftmetion of the hmgs after reimplantation. Most of t h e studies have been made on 3 dogs whielr have'been observed for periods of a N years, g ~ 2 years, and 2~/., years, respectively, after reimplautation of the left hmg. In 2 of the dogs the puhnonary cireulation does not appear m have been completely restored after reimplantation of the lung, but these dogs still serve to slmw the progress of hmg hmctiOn after operation.
METH
ODS'
Reimplantation In all dogs the left h m g was rdimplanted by a method similar to that of BiJeherl et aL [4]. From the Nuflield Dci)artment of Surgery, Radcliffe Iufirmhry, Oxford, England. Th~ inv~tigatior~ was supl~rt~], in part, by a grant from the Medical "Research Council Submitted fdr publication*Sept, 27, 1965.
AND
A,
J.
OF LUNG
GUNNING~
After e_xeision of the hmg, the vessels were washed through with hcparinizcd saline sotu/ion and the hilar structnrcs sutured in the order atrial 'cuff, bronchus, and p u h n o n m y artery. The eirctdation to the hmg was. inter.up to 2 hours. After-rehmg vessels and bronchi, the hmg was recxpanded by positive pressure and the elmst wall closed around two drains. which were connected to. a" water-seal bottle for a few hours, then clamped, and finally removed after about ~ hours.
Lung Fmwtion 7~sts Measurements of functional residual capacity, diffusing eapacity,-0xygen uptake, and pulmonary stretch reflex~.v; before reimplm,tatio~ and a~ in ~rward. Bronchospi~:om(3try ~,,as carried out" using the tube described previously [27]. The" m e t h o d s used were as:f011ows. Tliis was F U N C T I O N A L I I ~ I I ) U A L C A ! ,A C I T Y . measured by t h e closed-circfiit helium tebhniquc. Measurement was m a d e first on both hmgs a cuffed endotraeheal .tube and then. insertion of a bronehospirometry tube, on each h m g consecutively. DIFFUSING CAI AClTY
F O Il C h l t ~ N
~ I O . OXIDE,
The measurements .lungs combined, b) method described pre~ously [27]. ox~ each eters 185
JOlJRNAL OF SUROICAL BESI,;ARCI1
VOL, 6 NO, 5, ,nlhV ]966
and soda-lime cannisters. Measurements were • inade with a high oxygen concentration in each g'pirometer. PUL~[ONARY S'I]~ETCII REFLEXES. The stretch reflexes from each lung were tested a t bronchospirometry by inflating one lung with a pressure of 10 or 20 era. HeO. While inflation was maintained in this lung, the other lung was free to breathe from the spirometer system.
The Mechanical Properties of the L~lgs TIDAL VOLtn,~E. The md~lanical properties of tile two lungs are compared most readily by recording the tidal volume of each lun~ on the X and Y axes; respectively, of a cathc.~de ray oscilloscope [27]. The volume recordings were made'using low-torque pote~itiometers which were rotated.either by the strings of the.normal spirometers or by a pair of low-inertia wedge spirometers. If the nonelastic resistance o f each lung, relative to the tidal volume, is the same for the two h a g s , the tracing will move u p and down a straight line, and the slope of the li~ie is a measure of the relative c~;mpliance of the two lungs, In this situation the time constants of the two lungs are the same [29]. If the time constants are unequal, the tracing will describe a loop; the lung widl the smallest time constant (smallest nonelastic resistance relative to its compliance) will fill more rapidly at the start of inspiration and empty more rapidly at the start Of expiration. In none of the dogs were the time constantsso different that, during normal respiration, one lung bad begun to empty before the other nile had filled completely. ~ e ratio of tidal volumes of the two lungs v~as therefore a measure of the relative compliance" of itlae two lungs. In addition, simultaneous pressure-volume loops of each lung were recorded on a doublebeam cathode ray oseilloscope by applying a pressure signal, obtained from an intraesophageal balloon, to ~the ~." axis of the oscilloscope and the volume signals from the lungs, one to each beam, on tlle Y axis of tlie oscilloscope, UNIFOR~.ilTY OF VENTiIa~TION. ~ae nitrogen wasl~out 0f file lungs w a s meas~_~red by monitoring the expired nitrogen while the dog was ~6
q)reathing 100% oxygen, A comparative measure of the nitrogen washout in each hmg was obtained by sampling from each side.of th( ~ bronchospirometry tube in turn for four or five breaths while the dog x~;~as breathing I007~ oxygen. Another metl/od used to test tile uniformity of ventilation was suggested by Dr. Jere :\*lead (personal communication). Tlle dog was enclosed in a body plethysmograph, with breathing nlaintained through a cuffed endotracheal tube to the outside of th%plethysmograph. The airflow from the hmgs was measured by a pneumotachygraph On the plethysmograph and the outpu t was integrated to measure the volume expired. Flow was recorded on the Y axis and volume on the X axis of a cathode ray oscilloscope. A 10 liter aspirator bottle was evacuated to a pressure of ~200 nam. Hg, connected through to the endotracheal tube, and the curve of flow rate and lung volume recorded as the dog's lungs were collapsed. "~qth short rest periods between, the hmgs were emptied at slower, uniform rates by sucking out the lungs with a large piston punap. It has been shown (by Dr. :'dead) that, in normal lungs, when the n~aximum flow ~ t e falls at small lung volumes, the curves are superimposed whatever the initial rate of lung emptying. When lung emptying is not uniform, tile flow rates that can be attained at small hmg voh, mes are higher When the lung is emptied slowly and uniformly than when it is emptied rapidly with a powerful suction. DuS~rlNGOF "rile LUNG. An club: for, as described b y DuBois and Dautrebande [8], was used to produce a cloud of fine charcoal particles. Before a n d after inhalation of the particles into one of t_lae lungs, recordings of the tidal volumes of each hmg on coordinateaxes were made as described above. After an interval, recordings were made before and after inhalation into the other lung. Ten to 30 breaths of dust were taken into each qung, b rond~oscopy afterward showed a coating of dust i~x the bronchi. AEnOSOLINHALATION. A sol,.ltion of 3~/b histamine acid phosphate was nebulized in a DeVilbiss No. 40 nebulizer and the aerosol inhaled into each lung in'tt~rfi. Coordinate re-
XiAIISIIAIA. AND ( ; U N N I N G :
LONG-'YEI~,N! E F F E C T S
cordings of tidal volume were made before and after each inhalation.. 19 some experiments[ similar recordings were made after the inhalation of isoprenalinc aerosol. CILI:AItY ACHON. An attempt was first made to measure ciliary activity by placing, in one 6f the peripheral bronchi, a small deposit of radioactive gold adsorbed on to charcoal particle-s. The radioaet!vity along the bronchus was eotmted with the use of a collimated scintillation counter. The deposit of radioactive material could be located, but it did not move over a period of several hours, possibly because of the eft'oct of radiation on the cilia. Some estimate of eilia~, activity was obtained by placing a small deposit of India ink, adjusted to a pH of 7.5, down each bronchus and observing the rate of movement up each bronchus. coven m~:VL~<. The cough reflex was in. vestigated during I)ronehoseopy by touching the brcmehial m u c o s a with a probe. The response to chemical stimuli was tested by allowing the dog to l)reathe an aerosol of 2 5 ~ citric acid down each side of the bronchospirometry tube in turn. Anesthesia The measurements of hmg volumes mad diffusing capacity and the bronchospirometry were made after the dogs had been premeditated with too@line and ehlorpromazine and anesthetized with pentobarbital. The investigation of cough reflexes, reflexes to dusting, and ciliary action was carried out under vew light pentd)arbital anesthesia and also under ehloralose anesthesia.
RESULTS
Lung Function I'ULN[ONARY S~rltErCH I~EFLE~I:~. ~le H e r ing-Breuer stretch reflex, as reported by others [31], was absent in the rNmplanted hmg when tested a few months after operation. Inflation of the fight lung t o a pressure of 20 em. H~O produced an apnea lasting for 1 minute or more, but inflation of the left hmg had ahnost no effect on respimto W xhythm
"
~
OF
LUNG I I E I , M P L A N T A T I O N
.20 cmfH~O i lift.
~ g
tEFr
.
.
i
IN T I I E I)OC
:
..........
B
Fig. I. The effect of unilateral hmg inflation on the respirato W rhythm. (A) Dog 3, 2.',4 years after reimphmtation of the left lung[ (B) Dog 1, 3 ~ years after reimphmtation of the left lung.
(Fig. 1A). [n Dog 1, when tested 33-~ years after reimplantation of the left hmg, the Hering-Breuer r,Atex appears to be returning (Fig. IB): Inflation of the left hmg to a pressure of 20 cm. of water caused the interval between breaths to increase to almost four times that before inflation, whereas, 6 months previously, inflation of t h e l e f t lung h a d had Ve~ little effect on respiratory rhythm. Deflation reflexes Were also )nvestigated by applying a negative pressure to each lung in turn, but deflation ~ of one hmg inflated the other and made it impossible to assess the resuits. LV~-~C S~JZ. The funetionaI residual capacity of the two lungs, measured together and of each lung separately, is shown inFigure 2. LUNGCOZ-II'LIANCE. The relative compliance of t h e two lungs is indicated by t h e tidal volume of the left-lung, expressed as a percentage of the total tidal volmne (Fig. 3). A measure of the distei~sibility of the lungs which takes into account the Change in volume of the 187
J O U R N A L OF SUllCtCAL ]~ESEAItCII
VOL. 6 No. 5, ~XIAY ~966
DOG !
/
-
6"
~a0
V 4~
u: "'~,r,"'D06 ,30"
i veA~s AFTe~ ~E~MPLA~TAT~ON OF t e F T LUNQ
Fig. 4. The ratio of tidal w~lume to functional re,dual capacity (F.R.C.) of each hmg, measured before and at i,{tervals after reimplantation of the left Irreg.
oze. / \t
Fig. 2. The fnnctional residual capacity of tlae hmgs measured before and at intervals after reimplantation of the left lung. R = right lung, L = felt lung, R + L = l~th lungs measured together. 501
°1
the results of nitrogen washout measurements on the hmgs. These washout times did not differ appreciably from those of a control dog. In Dog 3 the left lung washed out more quickly than the right, blot the ventilation per unit of lung volume was much greater on the left thau o , the right. Curw~s of fJov., rate related to lung volume, obtained as described above, did not sho;,v, in any of the ~,,.gs, ;:~' that flow rates which could be achieved at low lung volumes were higher after the lungs had been emptied slowly than they were after r~nid emptying, q~aus this test did not show any evidence of unequal emptying of the lungs. . L ~ W A Y nESZSTANCE. An example of the recording of the tidal volume of the two lungs on coordinate axes is shown in Figure 5. In all TIOAL VOLUME
YEARS AFTER REIHPLANTATtON OF LEFT LUNG
Fig. 3. The ~dal volume of the left lung, expressed:as a percentage of the total tidal Volume, measured before and at intervals after reimp]antation of the left lung. hmg, is obtained by comparing the tidal volumes 'per 1 ~ ml.-0f: fu~ctionaI residual capacity. This is a measure of the specific cornpliance of the lung. Figure 4 shows the ratio of the s p e c i e compliance of t h e ~ght and left lungs. IJN'I~OR~-T'x" O F " ~ N q ~ T Z O r ¢ . Table 1 shows ~88
/;
RIGHT LUNG /
* 3 ¢
e .//';, f00 Hr. 4~*
|OO
TIDAL
VOLUHE
00(3 2
ML,
*LEFT~LUNG
Fig. 5. Tracings obtained by ooordinate recording Of tidal volume at bronchoscopy. For explanation see text.
.~IAI1SItALL ANI) G U N N I N G :
Table 1.
Dog No. 1
:~ 3
Both Lungs Years Time to After 2% Ne No. of Relmplant. (rain.) t~c.aths 3~ 7 23 2½ 5½ 32 2½ 7¼ 21
LONG-TEE.%I E F F E C T S
Dog No. 1 2
IIEI~IPLANTATION
IN T H E
Nitrogen Washout o[ the Lungs Tidal Vol,/100 ml. F.R.C. (ml.) Right Lung
Left Lung
30,0 31.8 ~,8
37,3 29.9 36,8
3 dogs, before reimplantation of the left hmg, file record during inspiration and expiration was a straight line, as shown for Dog 1 irl Figure 5. The record for Dog 1 remained a straight line after reimplantation, but the tracings for Dogs 2 and 3 became ~ anticlockwise loop with most deviation from the straight line on expiration (arrow pointing down, Figure 5). This ~implies that the time constants of the two hmgs are similar on inspiration b u t that the time constant of the left lung is shorter than that of the right on expination. cough ~mI-'LEXES. The cough reflex was investigated both under very light pentobarbital and under ehloralose anesthesia. Touching the larynx or lnovement of the bronehoscope in the larynx caused coughing: but mechanical stimulation of the bronchi below the carina or an aerosol of 25ct~ citric acid breathed through each side of tile bronchospirometry tube in turn did not cause coughing. RI:;FLEX B R O S C I t O C O N S T R I C T I O N , Inhalation of charcoal dust into each lung in turn, with'coordinate re~qrding of the tidal volumes, caused no change in the relative time constants of the two hmgs; neither was there any change in the relative compliance of the two lungs. Inhalation of histamine aerosol in the two Tal~le 2.
OF LUNG
Right Lung Time to 2% Nz No, of ( min.) Breaths 7 4 5)/2
23 31 32
Left Lung Time to 2% N~ No. of (rain.) Breaths 7 over 7 3
over 40 20
dogs ill which it was used caused a decrease in compliance in tile lUng which inhaled the aerosol. Tile results are shown in Table 2. Tile response of the left hlng was approximately equal to ~that of the right, Histamine did not change the shape of the loop obtained by coordinate recording~that is, it did not change the time constant of the lungs, Any change in nonelastic resistance was equal and opposite to the change in compliance. This effect w o u l d be produced if t h e histamine caused terminal airway closure rather than narrowing of the airvcays. OXYGEr: m'Tar:E. The percentage oxygen uptake of file left lung is shown in Figure 6. The value of 50% obtained for Dog 1 before operation is higher than float usually found in normal dogs and the postoperative valu~ of about 40% are in the normal range for the left lung. There has been no tendency for the oxygen uptake of the left lung to f aU with the passage of time. It is most probable that some vascular damage was produ-ced in Dogs 2 and 3 a t the time of operation and that this is the reason for the l o w ~values for the oxygen uptake of the left lung obtained postoperatively; there has been no further deterioration in Dog 2 a n d some recovery of function in Dog 3.
Effect of Histamine Aerosol on Lung Compliance and Tidal Volume
Control 34.7 31.7
Percentage of Tidal Volumeon Left Histamine: Histamine: Right Lung Control ~ f t Lung 40:7 36.6 32,5 34.2 31.7 27.8
Percentage Change in Compliance After Histamine Right Lung Left Lung ~22 --19 --11 ~16 ~89
JOUIINAL O F SUIIGICAL IIESEAIICII
z
.a
VOL,
6
xo.
50 ¸
.0Too ~g
~'0
5, .xtav
1966
figures can be given for the ciliary activity of the right and left main-stem bronchi. In 2 of the dogs, however, the India ink injected, into the bronchi traveled up comparable lengths of the right and left main-stem bronchi to the carina in the same time. In the other dog the rate of movement on the left side was only about one.third that on the right.
Ilistological Findings
o
Fig. 6. The oxygen uptake of the left hmg, expressed as a percentage of the total uptake, measured before and at intervals after reimplantation of the left lung. ~ e measurements of oxygen uptake were made with the dogs breathing a high oxygen concentration from each of the spirometers. Under these conditions the blood leaving each lung is fully saturated with oxygen, and since the inixed venous blood entering eac4a lung has the same oxygen content, the a~eriovenous oxygen difference o f each lung will be the same, The ox),gen uptake of each hmg is therefore proportional to the blood flow through each lung. ~IE
DIFFUSING
C~PACITY
FOil CAllllO:'4 ~[ONOX-
row. The°results of measurements of the diffusing capacity of both lungs for CO are shown in Figure 7. cILIAmt" Ac':~w~r~". No precise quantitative ttl
a
x O
g
B2-
It "x"
YEARS AFTER REIIHPLANTAT!ON~
tEFT tUN6
Fig. 7. The diffusing capacity of the lungs for carbon monoxide, measurecl before and at intervals after ieimplantation of the left lung. ~9o
Dog 1 died of pneumonia a few days after the final measurements reported here were m a d c ~ t h a t is, 3:~{ years after reimplantalion of the left lung. At autopsy hoth hmgs showed patd~y consolidatign, rather more on the right side than the left, but the left lung had no adhesions arid otherwise appeared normal. The lungs were inflated with formol saline and allowed to fix. q'be puhnonaD, artery suture line was almost invisible, and tile suture line and the main branches of tile arte W showed no evidence of thrombosis. Similarly, the suture line in the left atrium was also clean, and all the main pulmonary veins w e r e patent: The bronchus had healed well, with only a small crescent of mucosa pulled into the lumen on the medial wall. Blocks of tissue were taken for histological examination from above the bronchial suture line, across the suture line, at 1, 3, and 5 era. below the suture line, and from the periphery of the lung. Blocks were also taken across the atrial and pulmonary artery suture lines, and from the right lung for purposes of comparison. The sections were stained with hematoxylin and eosin and with Hohnes's stain for nerve fibers. The small bro~ehial arteries in the sections were not appreciably different in the two brags, and no evidmace was found of fl~rombosed or obliterated arteries. There was considerable peribronchial and periarterial edema in bofl:t hmgs, presumably the result of the pneumonia. In the left lung, lmndles of nerve fibers were found in branches of'the bronchi down to 1.5 ram. diameter. F a i l u r e to field them in branches smaller than this was probably due m inadequacy of tlle staining technique; Some of the nerve brandies were within sheatlis, but around oth6rg ~o sheaths were
51IARSIi[ALL AND G U N N I N G :
LONG-q['EtlNI E F F E C T S
evident. "/Tie number of nerve bundles was approximately file same in the left as in the right hmg. Peribronehial ganglia were not seen in any of the sections taken from below the suture line.
DISCUSSION
The purpose of this study was to investigate tile changes in hmg function, particularly long-term changes, which might occur in lungs that have no bronchial arterial or nerve supply. Although many experimental animals have a well-marked stretch reflex from the hmgs [36], the role of stretch reflexes in man is still under inves6gatiom Widdicombe [35] showed that man has only a w,'eak HeringBrcuer reflex. Recent experiments involving Mocking of both vagi in man [15] show that the vagi are not essential for maintenance of a nonfiaI respiratory rhythm although vagal block does appear to allow some prolongation of breath-holding time. In hmg reimplantation or transplantation all the nerves {o and from the lung are severed, and this may have a greater influence d~an vagal section only. Several worl-:e~ have reimplanted one lung and, at a later date, removed the other [i, g, 10, 13, 17, 19, 23, 37]. In some of file animals, respiration became slower and irregular after removal of the normal hmg [I,'~, 19, 23], but in others no abnormality was reported. Most of the animals subjected to pneumonecton@ of the normal lung started spontaneous breathing after operation. ~ l e respiratory paralysis fllat Howard and "~Vebb [20] found after total denereation of the lungs has been attributed to damage to tile phrenie nerves [13]; however, respiratory para}ysis was usually associated with high denervation of the trachea, and it is possible thae receptors in the trachea and larynx may be suflqcient in some anfinals for the maintenance of rhythmic respiration. The cause of death after pneurnonectomy in many of the animals, as also in those after occlusion of t!-.e contralateral pulmonary artery, is pulmonary edema caused by the high
OF
LU N G
REINIPLANTATION
IN T I l E
I~G
pulmonary arterial pressure [4, 6, 18]. Duvoisin et al. [10] suggest that the cause of det~tb in their own series, and in those reported by others, was due to damage in tile reimplanted lung. A normal dog can exist oll only ~ % of its puhnonary vascular bed [16] so that if death is due to.puhnonary insufficiency the denervation of the hmg, or al}sence of the hronddal arterial supply, may play a part in causing death; however, as discussed below, no evidence was found that rei|nplant~rtion 1-ms any effect on the tone of the p u l m o n a ~ vessels. In studies which have been reported previously, no evidence of a return of the IleringBreuer reflex has been found, Portin et aL [31] found that the Hering-Breuer reflex was s~lI absent in a dog 35 months after reimplantation of tim lung although in the dog at autopsy numerous nerve fibers were found below the suture line in both the pnhnonary artery and the bronchus. The retunl of the Hering-Breuer reflex in Dog I, .3~/~ years after reimplantation, appears to be the first instance reported of restoration of the reflex. In this dog, too, nerve trunks were found in the peribronehial tissues. If st retd~ reflexes are essential for normal function of the lungs, fllen regeneration of the puImona W nerves may be important in patients in Mmm hmg transplantation is carried out and who may require eontralateral pneumoneetomy at a later date. In these (togs eMdence was sought for the presence of reflexes other than the stretch reflex. The cough reflex might be important in preventing infection in the lung, although a cough is probably concerned mairJy with clearance of the trachea and main bronchi raffler tllan of the smaller'bronchi [26]. If bronchial secretions .are present on the normal side, or if secreOons on the reimplan~d side are moved as far as the c a n n a by ciliaW action, any cough induced will be equally effective on both lungs. The lower airways of a dog are noted for their insensitivity to ~ e cough reflex, and in the dogs studied here, in spite of the very light anesthesia and a sensitive IaryngeM reflex, no reflex could be obtained from the lower airways. The inhalation . of ~dust has been reported 191
JOURNAL OF SUI1GICAL IIESEARC|I
VOL. 6 NO. 5 , ),lAY 1 9 6 ~
to cause an increase in airway resistance due to a nervous reflex from the bronchi [36]. In these dogs. no bronchoconstrietor effect was found, either in the normal or in the reimplanted lung. This could be due to insensitivity in the method used, but the method would llave detected a change of the order found by Widdieombe et aL [36]. Another reason for the absence of reflex could be that the receptors are mainly in the upper trachea. It has been suggested that emphysema is more liable to develop in reimplanted h.mgs than normal hmgs. This could happen if loss of the nerve supply to the hmg resulted in bronehiolar eonstricti0n or if the ,absence of a bronchial blood supply caused irnpairment of the elasticity of the hmg tissue [7]. One di~culty in following dogs such as these over a period of years is that the dogs' ages are unknown, and it is often difficult to be certain of their maturity. ~ m s 2 of the dogs studied, and also 1 control dog, wllich was studied over a period o~ 2 years, showed an increase in the hmctional residual capacity of the lungs v,,hieh was probably related to maturity rather t h a n ' t o the development of emphysema, although marginal emphysema is not uncommon in dogs. During the period of observation the weight of Dog 1 increased from 15.0 to 16.0 kg., that of Dog 2 from I5.0 to 16.4kg., and that of Dog 3 from 15.9 to 20.0 kg. ~ e increase in the size of the hmgs in Dog 3 has resulted from increase in the volume of the right hmg rather than that of the left, but damage to the pulmonary circulation may be responsible for the failure of the left lung to grow. The changes in lung volume found at the final measurements in Dog 1 m a y b e due to the development of pneumonia from which this dog died 3 days later. The relative eomplianee of the two lungs (Fig. 3) does not change appreciably over the.years. In view of the changes in lung size, the specific compliance of the hmgs (compliance per unit vo]nme of lung) is a better indication of any change in lung elasticity Milch may have taken place. T]~e specific compliance of the left lung, relative to that of the right (Fig. 4), tended to fall over the years in Dogs 1 and 2, but in Dog 3 there :t9e
was no significant change from the rather low vMue immediately after operation, ~-m change in specific compliance of the hmgs at the end of the period of observation, compared with thc values before operation, were for Dog l, right lung - - 1 9 ~ , left hmg --7'~;, Dog 2, right lung -[-20~, left hmg + g6¢fi, and Dog 3, right lur, g -- 16%, left hmg + 33~?;. These figures, taken in conjunction with those for changes in lu,ig voh, me, do not indicate any tendency for the reimplanted hmg to become more distensible or more fibrosed than the normal lung. The measurements of the time constants of the two hmgs also indicate that the time constant of the reimplanted hmg is not incrc
.~IAIISItALL AND C U N N | N G :
LONG-TEIt~I
corded by, bronehospirometry. In none of the dogs did the relative oxygen uptake of the hmgs change during infllsion, as would be expected if the pulmona W vessels in the reimplanted hmg were snlqeet to vasoconstriction thaicould be relieved by aeetyleholine. A deerease in the relative blood flow through a reimplanted hmg is more likely to be due to vascular thrombosis following operation than to active vasoconstriction. q>n months after reimplantation of the hnlg in Dog 1 measnrements were made of differential hmg blood flmv during the breathing of anoxic gas mixtures by each of the lungs in turn. Anoxia of ei0mr hmg caused a shift of blood flow to the other lung. TMs response to anoxia wmdd be expected to occur since it also happens in the isolated perfused lung [91.
The total diffusing capacity of the hmgs for carbon monoxide in the dogs remained unehange~t or even increased after reimplantation, This does not indicate that the dog still has a good diffusing capacity in the reimplanted lung. q31e diffusing capacity, remained unchanged after reimplantation in another dog which was later discovered to have a completely fil)rosed Ieft hmg. In some species the cilia are partly under the control of the nervous system. The piflatal cilia of the frog are normally immobile but may be made to beat by neural stimulation [25]. The cilia of vertebrates beat continuously, even in tissue culture [32]. Direct observation of the cilia in the duck and turtle [ ~ ] failed to show that the rate of beat was influenced by nerve stimulation. Shmagina [33] showed, however, that a small load placed on the tracheal cilia of the dog or cat was moved more rapidly when the vagus was stimulated and more slowly when the sympathetic nerw~s were stimulated. The evidence for direct nervous control of the cilia is not supported by anatomical studies for neither in the dog, rabbit, nor man has any nerve supply been foufid to die cilia [11, 21, 22, 34]. The efferent nerves to the bronchi all end in the smooth muscle or around the brondlial glands. Pi6ron [30] and also Gordonoff [14] have suggested that nerves may, have an in-
EFFECTS
OP" LUNG
ItEI.~II'LANTATION
IN T I l E
I)OG,
direct action on cilia W activity by dmnging the composition of the liquid layer in whicli the cilia work. The ciliary activity in the lungs of these dogs measured, 2 to 3 years after reimplant;3tion, was not obviously decreased, and there is no reason to suppose that a reimplanted or transplanted hmg is more liable to retain secretions than a normal lung. It is of interest that when Dog 1 died of pneumonia, the right. hmg was affected more severely than the left. The lymphatic vessels are also divided at the time of reimplantation of the hmg. Although Nigro et aL [~S] reported dilated lymphatic channels in the re.implanted lung several months after operation, Eraslm{et aL [12] have shown that mlmerous lymphatic vessels cross the suture line by 30 days after operation. qqm reimplanted hmgs of these dogs were not clinically edematous and the compliance was not reduced so there is no evidence of significant lymphatic ohstruetion in the reimplanted hmg. The eNeiency of the lymphatic circulation, however, may be an importm~t factor if the other lung is removed; total pneumonectomy may cause the pulmonary arterial pressure to rise and ilierea:se the exudation of fluid into the reimplanted lung.
CONCLUSIONS
II~ese experimene~ on reimplantatimi of the lung in normal dogs indicate that the hmg may function normally for many years and may even regain its stretch reflex. Transplantation of the hmg in.man, .however, may iiitroduee long-term complications oflmr than those due to immunological di~eulties. A lung, or a lobe, will probably be transplanted most commonly in patients in whom the re~ maining lung is eidmr fibrosed or emphysematous. If the remaining hmg is fibrosed, the presence of an adequate amom~t o f normal (transplanted) hmg in the thorr~ will mean that the stiffer, fibrosed lung will expand very little during inspiration, al!d it wi!l probably undergo a progressive contraction. This may have two disadvantages: first, the con59a
J O U I t N A L OF SUItGICAL llESGAIIClI
YOL. 6 NO. S~ ;NIAY
tracted inactive lung will provide a site for bronchial infection; and second, if the h m g contracts down completely, there is the danger that stretch 'reflexes will not be stimulated. ~-~e stretch reflexes, however, may not be essential for normal respirat!0n, If transplantation of the h m g is done for emph'ysema, tim remaining em.physematous h m g will probabl>; remain distended and take v e w little part in gas exchange. On inspiration th'e transplanted lung will distend more easily, a n d on expiration it will empty before the emphysematous hmg. Again there is the possibility of inadequate stretch reflex activity. A n o t h e r possible d a n g e r is that the ernl£hysematous h m g will continuQ to expand and compress the transplaot, in much the same way that solit~ry lung cysts can expand and compress normal lung tissue. This might happen in patients with primary emphysema raffler than in those with emphysenaa secondary to chronic bronchitis. A transplanted lobe w o u l d be m o r e ' v u l n e r a b l e than if a whole lung were transplanted. SUMMARY Physiological measurements of h m g function, including bronehospirometrie measurerncnts, have been m a d e on 3 dogs for up to 33,~ years after reimplantation of the left iung. T h e r e is no evidence that the reimplanted l u n g degenerates more rapidly than the norreal lung. T h e hmg does not show any evid e n c e either of fibrosis or of over distention, and the airway resistance is commensurate with h m g size. c i l i a w activity is also normal in .the reimplanted~ lung. The blood flow thr.gugh t h e reimplanted Itmg is nomla] unles~ vascular obstruction, o c curs at the time of operation. No evidence of vasoconstriction was found in the reimplanted lung. ~ l e lung stretch reflexes are absent initially b u t s h o w evidence of r e g e n e r a t i o n after several years; Other reflexes f r o m the bronchi, such as the cough reflex and bronclaoeonstrietor.reflexes, were looked for but were not demonsti'ated in effher hmg. 194
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195