the learning curve for laparoscopic cholecystectomy.pdf

The Learning Curve for Laparoscopic Cholecystectomy

The Southern Surgeons Club’, Michael J. Moore, PhD, Charles L. Bennett, MD, PhD, Durham, North Carolina

BACKGROUND: The use of laparoscopic surgical procedures without previous training has grown rapidly. At the same time, there have been allegations of increased complications among less experienced surgeons.

METHODS: Using multivariate regression analyses, we evaluated the relationship between bile duct injury rate and experience with laparoscopic cholecystectomy for surgeons in the Southern Surgeons Club.

RESULF~: Fifty-five surgeons performed 8,839 procedures. Fifteen bile duct injurles (by 13 surgeons) resufted wlth 99% of the injuries occurring within the first 30 cases performed by an individual surgeon. Multivariate analyses indicated that the only significant factor associated wlth an adverse outcome was the surgeon’s experience with the procedure. A regression model predicted that a surgeon had a 1.7% chance of a bile duct injury occurring in the first case and a 0.17% chance of a bile duct injury at the 50th case.

CONCLUSIONS: While surgeons appear to learn this procedure rapidly, institutions might con- sider requiring surgeons to move beyond the initial learning curve before awarding privileges. Am J Surg. 1995;170:55-59.

S ince its introduction in 1988, laparoscopic cholecystectomy has gained widespread acceptance among surgeons in the United States and abroad. The diffusion

of this technology was unprecedented, in that there were few reports on the benefits, risks, and cost effectiveness of the

From the Department of Economics, The Fuqua School of Business (MJM) and the Center for Health, Policy Research and Education, Duke University Medical Center, and the VA Medical Center, Department of Medicine (CLB), Durham, North Carolina.

*Members and associates of the Southern Surgeons Club who contributed to this study and other participants are listed in the Appendix.

Grant support: Dr. Bennett is a recipient of a Senior Career Development Award of the Veterans Administration.

Presented in part at the National Institutes of Heafth Consensus Development Conference, “Gallstones and Laparoscopic Cholecystectomy,” Bethesda, Maryland, September 14-16, 1992.

Requests for reprints should be addressed to William C. Meyers, MD, Chief, Gastrointestinal Surgery, Duke University Medical Center, Durham, North Carolina 27710.

Manuscript submitted April 51994 and accepted in revised form August 16, 1994.

procedure. In addition, uncertainties exist over whether laparoscopic procedures are as safe as open cholecystectomies. Injuries to the bile duct during open cholecystectomy occur in approximately 0.1% to 0.2% of cases.1,3 In contrast, a previous study of 1,5 18 cases of laparoscopic cholecystectomies by the Southern Surgeons Club found a rate of 0.5% for bile duct injury during laparoscopic cholecystectomy and a rate of 0.2% for injury not recognized at the time of the initial surgery.4 The injury rate decreased with experience. There was a 2.2% incidence of bile duct injury in the first 13 patients operated on by each surgical group compared to 0.1% for subsequent patients. While there have been allegations of increased complication rates among individual surgeons during the early period following laparoscopic training, no previous study has documented how quickly individual surgeons are able to learn the procedure.

Previous studies have shown better outcomes when surgeons perform higher volumes of more established procedures, such as coronary artery bypass grafts, gastrointestinal operations, total hip replacements, abdominal aneurysm repairs, prostatec- tomies, hysterectomies, and vascular repairs5-10 However, the previous studies of the volume-outcome relationship have suf- fered from methodologic limitations. The previous studies have usually been based on cross-sectional data representing information on procedures performed at one period of time, rather than longitudinal information on procedures performed over longer periods of time.5 Also, few studies have evaluated the relation between physician (as opposed to surgical group or hospital) experience and outcomes. Finally, studies on the volume-outcome relationship have not addressed new procedures, such as laparoscopic cholecystectomy.

The policy implications of a volume-outcome relationship depend on the functional form of the relationship.11*13 If the likelihood of an adverse outcome continues to decline as caseload increases, then the goal should be to limit care to a very few surgeons and centers. However, if there is a threshold effect (surgeons having performed more than a minimum number of cases have better outcomes), then the goal should be to assure that patients are referred to surgeons who have reached this threshold. Learning programs might be required so that experienced surgeons accompany those with less experience until the threshold number of cases is performed.

This study was designed to evaluate the relationship between volume and outcome for laparoscopic cholecystectomy using data that transcend the limitations of previous studies. In particular, the analyses used longitudinal data, evaluated a new procedure, and addressed the volume-outcome relationship for individual surgeons rather than for groups of surgeons. In addition, this study investigates whether the volume-outcome relationship identified in the

THE AMERICAN JOURNAL OF SURGERY* VOLUME 170 JULY 1995 55

.APAROSCOPIC CHOLECYSTECTOMY/SOUTHERN SURGEONS CLUB 1

initial experience of the Southern Surgeons Club applies to individual surgeons and, if so, is the relationship of the con- tinuous or threshold type.

METHODS Surgeons

A total of 20 participating surgical groups and 55 individual surgeons contributed data to the study. The participating surgeons were all members of the Southern Surgeons Club, a group comprising academic and private surgical practices. Each surgical practice had to submit data on all cases. The participating surgical groups practiced in the following states: Alabama (2 groups); Florida (2 groups); Georgia (1 group); Kentucky (1 group); Louisiana (2 groups); Maryland (1 group); Massachusetts (1 group); Mississippi (1 group); North Carolina (3 groups); South Carolina (1 group); Tennessee (3 groups); and Virginia (2 groups).

In this analysis, the definition of “academic” as opposed to “private practice” was based on whether residents regu larly participated in the laparoscopic procedures. Ten groups (26 surgeons) practiced in academic centers and 10 groups (29 surgeons) practiced in private hospitals. The academic groups averaged 2.6 surgeons per group (range 1 to 6) and the private-practice groups averaged 2.9 surgeons per group (range 1 to 6). All surgical groups began doing laparoscopic cholecystectomy from June 1989 through July 1992. This study continued through May 1993.

Cases and Complications A case was defined as a laparoscopic cholecystectomy if

the entire procedure was initially intended to be performed through the laparoscope and no laparotomy was planned for any purpose other than the insertion of trocars. To en- sure uniformity of reporting with respect to surgical complications for this report, we restricted the analysis to cases of bile duct injuries. Bile duct injury was defined as any (iatrogenic) traumatic disruption of the major hepatic biliary system, other than simple biliary leakage. For confir- matory purposes, the surgeons also reported biliary leak- ages, details of the actual injuries, and relevant historical information on the patients with injuries. Biliary leakage was defined as a documented, clinically significant bile col- lection that was not associated with major biliary injury, nor with a documented disruption of the major biliary system. Thus, the major biliary system is defined as the major hepatic radicals or common duct and not the gallbladder, gallbladder bed, or cystic duct. The total incidence of biliary leakage among the 8,839 patients was 0.44% (39 patients). Follow-up on all patients was at least 6 months. Liver function tests were ordered at follow-up, however, only if indicated clinically.

Data Analysis Data on individual surgeon experience were analyzed us-

ing multivariate probit regression models.14 The unit of analysis was the individual patient. The outcome variable was a dichotomous indicator variable reflecting the occur-

rence of a bile duct injury. Probit regression analysis ‘was used to estimate the effects of potential predictor variables on the likelihood of a bile duct injury. The probit regres-

sion model assumes that the binary outcome is related to the predictor variables according to the relationship Prob [a, = l] = F(RX,), where i indicates the observation, a, the outcome at case i, Xi a vector of explanatory variables, and F the cumulative normal distribution function. The predicted probability of an accident at experience level 0 (ie, Prob [a, = 11) is then equal to F(BX,), where R indicates the estimated parameters.

Predictor variables included practice-level factors (ie, number of surgeons in the group, private versus academic practice) and surgeon-level variables (ie, age, experience with laparoscopic cholecystectomies). Surgeon experience was defined as the natural logarithm of the number of previous cases. The log form was used to correct for skewness of the data and because of the direct relationship of the experience variable with the rate of learning.

Separate regression models were estimated for academic surgical groups and private-practice surgical groups. Al- though the model for private practices predicted a slightly higher chance of an injury during the first case relative to academic surgeons, there were no statistically significant dif- ferences in the predictions from the two models. Therefore, we present data for all 55 surgeons. Because only 4 surgical groups had more than 1 accident (1 group represented a practice with only 1 surgeon, 2 groups had 1 surgeon with 2 ac- cidents, and the fourth group had 2 surgeons each with 1 accident), intrapmctice correlation effects were not estimated. Because of the infrequent occurrence of more than one accident per group, it is highly unlikely that these effects would significantly alter estimates of physician learning.

RESULTS Surgeon Profiles

The 55 surgeons reported performing a total of 8,839 laparoscopic cholecystectomies for the treatment of gallbladder disease (Table I). Of this total, 4,986 (56%) were performed by private-practice surgeons and 3,853 (44%) by academic surgeons. The average age of the private-practice surgeons was 48.6 years (standard deviation [SD] 7.8) and the academic surgeons’ average age was 43.5 years (SD 7.4).

The 20 surgical groups had participated in similar training procedures. Generally, all surgeons attended a 2- to 3-day course with hands-on experience with animal models. Thereafter, surgeons were supervised by an experienced la- paroscopist during subsequent procedures, with the number varying according to local hospital and surgical group stan- dards. On average, surgeons with little experience with laparoscopic cholecystectomies were supervised by a more experienced surgeon for 10 cases.

Details of Injuries A total of 15 bile duct injuries occurred in the 8,839 cases

of laparoscopic cholecystectomy. Two surgeons had 2 patients who sustained injuries, 11 surgeons had 1 patient with an injury, and 42 surgeons had no patients with injuries. Thirteen percent of the 15 injuries (2 cases) occurred within the first 5 cases, 13% (2) occurred during cases 6 to 10,33% (5) occurred during cases 11 to 15, and 7% (1) occurred between the 16th and 20th cases (Table I).

Eight of the 15 (53%) ductal injuries were of the “classic”

56 THE AMERICAN JOURNAL OF SIJRGERYm VOLUME 170 JULY 1995

LAPAROSCOPIC CHOLECYSTECTOMY/SOUTHERN SURGEONS CLUE _____

TABLE I

Experience of the Southern Surgeons Club With Laparoscopic Cholecystectomies

Academic Private Practice (n = 26) (n = 29)

Average no. of surgeons per group 2.6 2.9

Range l-6 l-6

Average age (y) 43.5 48.6

Standard deviation 7.4 7.8

No. of cases (%) 3,853 (44) 4,986 (56)

Average no. of cases per surgeon 162.5 159.2

Standard deviation 162.5 160.0

Bile duct injuries by surgeon experience’

Never had an injury 20 22

Injuries occurred within:

l-5 cases 0 2

6-10 cases 2 0

11-15 cases 3 2

16-20 cases 0 1

21-25 cases 0 1

>25th case 1 3

‘Two pnvate phyxians had two injuries each.

type in which the common duct (or other part of the major extrahepatic Mary system) was misidentified as the cystic

duct. This duct was transected, with a variable amount of

dissection up the portal hilum. The remaining 7 (47%) in-

juries were simple lacerations or punctures of the major bile

duct. Three of the 15 (20%) injuries were common duct

side-wall punctures that occurred as a result of cholangiography (ie, too aggressive insertions of cystic duct catheters).

Nine of the 15 (60%) injuries were unrecognized at the orig-

inal operation. Two patients developed biliary strictures recognized 2 and 4 weeks after surgery. No other late strictures

were seen. Seven of the 15 (47%) patients underwent

cholangiography, whereas only 29.4% of the total 8,839 pa-

tients underwent cholangiography. Five of the 7 injured pa-

tients who had undergone cholangiography had their injuries

discovered at the original surgery.

In 10 of the 15 cases of injury, the operation was performed

by a 2-surgeon team, whereas a solo surgeon performed the operation in the other 5 cases. The indications for laparo-

scopic cholecystectomy for the cases with injuries were:

chronic cholecystitis (8 patients), acute cholecystitis (5 patients), pancreatitis (1 patient), and gallbladder cancer (1

patient). All patients underwent surgical repairs of the injuries, either immediately or eventually. Eight patients un-

derwent Roux-en-Y hepaticojejunostomies and 7 patients

underwent primary repair of the injuries or lacerations, with or without T-tubes.

Probit Analyses

Probit regression analyses were used to assess the chances of bile duct injury as a function of the cumulative experi-

ence of a surgeon with laparoscopic cholecystectomy. The only significant factor associated with an adverse outcome was the experience of the surgeon with the procedure (P =

0.001) (Table II). Nonsignificant covariates included physician age, academic or private-practice affiliation, and size of the surgical group. The Figure illustrates the proba,

TABLE II

Probit Regression Model Predicting the Probability of a Bile Duct Injury as a Function of Surgeon-Level

and Surgical Group-Level Characteristics

Characteristic Coefficient Standard Error P Value

Intercept -1.957 - -

Surgeons Experience’ (log) -0.234 0.056 0.001

Age -0.0006 0.010 NS

Surgical groups No. of surgeons -0.023 0.055 NS

Academic practice -0.068 0.182 NS

‘Expenence IS defined as the number of laparoscopic cholecystectomies performed by the surgeon. NS = not s/gn/ficant

0.02

g 0.015

6

2 0.01 2

5 0.005 n

0 0 5 10 15 20 25 30 35 40 45 50

Experience (Number of Procedures Performed)

Figure. The graph shows the predicted probability of a bile duct

injury as a function of surgeon experience with laparoscopic cholecystectomy.

bility of bile duct injury with respect to individual surgeon

experience with iaparoscopic cholecystectomy, based on the

regression analysis results. The figure indicates a rapid learn-

ing effect, whereby most of the learning occurs in the first

15 to 20 cases. The model predicts an injury rate of 1.7%

for surgeons with no prior experience, 0.73% after 5 cases,

0.48% after 10 cases, and 0.3 1% after 20 cases.

Approximately 90% of bile duct injuries are predicted to

occur during the individual surgeon’s first 30 cases. After 50

cases, surgeons are predicted to have an injury rate of 0.17%,

one tenth of that associated with inexperienced surgeons.

COMMENTS Laparoscopic cholecystectomy is the preferred treatment

for removal of the gallbladder. This report of 8.839 cases

indicates that the Southern Surgeons Club has experienced

few technical problems. Ninety percent of bile duct injuries

occurred during the first 30 cases performed by individual

surgeons in the study. A regression model predlcted that the chances of a bile duct injury occurring during a proce-

dure conducted by an experienced surgeon decreased from 1.7% during the first case to 0.17% after 50 cases. The

model also predicted that the rapidity of learning laparoscopic cholecystectomy was not significantly related to physician age, number of surgeons in the practice, or whether the hospital setting was academic or private prac-

THE AMERICAN JOURNAL OF SURGERY” VOLUME 170 JULY 1995 57

tice. Of course, the injury rates cited in this study under- estimate the actual rate, since final follow-up was only 6 months. The likelihood that the rates are underestimated is supported by the 0% incidence of late strictures. Most series of bile duct injuries include patients with strictures recognized 6 months after operation.

Most surgical groups and hospitals acknowledge that training programs for laparoscopic cholecystectomy are es- sential. However, there is a variation in the types of training practices. The summary statement from the recent National Institutes of Health Consensus Development Conference on “Gallstones and Laparoscopic Chole- cystectomy” addressed this issue: “Strict guidelines for training in laparoscopic surgery, determination of competence, and maintenance of quality should be developed and im- plemented promptly. The formulation of such guidelines will require the involvement of various professional soci- eties (eg the Society of American Gastroenterologic Surgeons [SAGES]), credentialling committees, certifica- tion boards, and educational oversight groups.“15 One ex- ample of a specific policy recommendation is found in the advisory statement of the Department of Health of New York State in which inexperienced surgeons are advised to serve as an assistant for 5 to 10 cases and have an additional 10 to 15 cases performed under supervision.r6

Almost all of the surgeons in this report have participated in intensive courses that included hands-on experience with animals. In addition, all inexperienced surgeons were supervised by surgeons who had extensive experience with laparoscopic techniques. Usually the first 10 cases were done with close supervision. Our data predict that the Southern Surgeons Club would have experienced about 17 injuries during the first 10,000 cases of laparoscopic cholecystectomy. However, if the New York State policy were adopted (ie, the first 15 cases were performed with supervision) and it is assumed that the injury rate during the early phase is similar to that for a surgeon who has done 50 cases, the model predicts that 10 of the 17 bile duct injuries might have been prevented. More stringent policies requiring supervision of greater than 15 cases are predicted to have much smaller effects on decreasing the expected number of bile duct injuries.

A previous study found evidence for a learning curve for open cholecystectomy.6 The study, based on 25,091 cases of open cholecystectomies performed by 2,322 surgeons, included in-hospital mortality as the outcome measure (which occurred in 1.4% of the cases). The study found that hospital volume was the more significant volume measure, but physician volume was marginally related to mortality rates. The authors of the study hypothesized that the relationship between high surgeon volume and good outcomes for open cholecystectomy was more likely to be found among complicated procedures. In contrast, in our study, 90% of the complications were noted among the early cases for individual surgeons; these generally represented less complicated cases.

A learning curve for laparoscopic urologic procedures has also been described previously.17 In this study, a regression model predicted that the chances of a complication occurring during a procedure decreased from 1.0% during the first

LAPAROSCOPIC CHOLECYSTECTOMY/SOUTHERN SURGEONS CLUB 1

case to less than 0.2% after 8 cases. Additional training after attending a 2-day training seminar was the only other significant predictor of complications. As in our study, practice setting (academic versus private practice) and number of physicians in the practice did not correlate with the subsequent rate of complications.

The present results of a learning curve for laparoscopic cholecystectomy are also consistent with those reported for other surgical procedures, such as coronary artery bypass grafts, abdominal aortic aneurysm repair, and hip surgery.6-13 However, the functional form of the learning curve relationship for laparoscopic cholecystectomy is of the low- threshold type, whereby good outcomes are predicted to occur after 10 to 20 cases. Factors considered important in the development of major ductal injuries with laparoscopic cholecystectomy include: proper visualization of the operative field, recognition of the relevant anatomy, and good judgement about when to convert to open cholecystectomy.18 These factors are consistent with a low-threshold type of volume-outcome relationship.

The policy implications of a low-threshold volume-outcome relationship are different from those that apply to high-threshold, or continuously decreasing, volume-outcome relationship. With a low-threshold volume-outcome relationship, strategies that allow for training and close supervision of inexperienced surgeons should be adopted and are likely to be associated with good outcomes. These data should also encourage surgical residency training directors to incorporate threshold numbers of cases into their programs for laparoscopic cholecystectomy. In contrast, policy makers have created regional centers of excellence for procedures such as coronary artery bypass grafting, which have a high-threshold volume-outcome relationship.

This report does not evaluate the volume-outcome relationships for other new endosurgical procedures. These data should develop soon. Proper interpretation of information on new procedures should take into account two important factors: (1) experience with endosurgery in general, and (2) consistency of the operative technique (eg, repair of inguinal hernia has a lack of consistency with respect to operative technique). These data on laparoscopic cholecystectomy are relatively pure. The operation was the first experience in endosurgery for all of the surgeons. In addition, the technique simply involved removal of the gallbladder; in other words, with the exception of the specific instruments used, the procedure was remarkably consistent.

This study overcomes several limitations associated with the previous reports of volume-outcome relationships. By evaluating a large number of surgeons performing a new procedure over several years, effects related to learning-by-doing were clearly identified. Previous cross-sectional studies of the per- formance of established procedures by surgical groups or hospitals have had difficulty identifying the effects of individual surgeons. In addition, most reports have retrospectively evaluated in-hospital mortality as the relevant outcome.

The methodology used in this study suggests that coordi- nated efforts to establish registries, such as those of the Southern Surgeons Club, may be helpful to policy makers who are involved in evaluating and regulating the diffusion of new technologies.

58 THE AMERICAN JOURNAL OF SURGERY@ VOLUME 170 JULY 1995

[ LAPAROSCOPIC CHOLECYSTECTOMYlSOUTHERN SURGEONS CLUB1

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the relation between hospital volume and outcomes for selected di-

agnostic categories. Mrd Care. 1984;22:98-114.

13. Maerki SC, Lufr HS, Hunt SS. Selecting categories of patients for

rcgionalizari~m: imphcations of the relationship between volume and

outcome. Mtid Care. 1986;24:148-158.

14. Maddala GC. Limited-Dependent and Qualitative Variables in Econometrics. Cambridge. UK: Cambridge University Press; 1983.

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I+aroscopic cholecystecomy. Am J Surg. 1993;165:527-532,

16. New Yurk State Department of Health Memorandum, Health

Facihties Series H-18. June 12, 1992.

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18. David& AM, Pappas TN, Murray EA, et al. Mechanisms of ma-

J(X hihxy injury during lapxoscopic cholecystectomy. Ann Surg. 1992; 215:1Y6-202.

APPENDIX W&am (1. Meyers, MD, Sean Sue, BS, Charles L. Bennett, MD, PhD,

Ravi Chatl, MD, Mary Ann Iannacchione, RN, Michael J. Moore,

PhD, Elizabeth A. Murray, RN, Theodore N. Pappas, MD, Duke u nweaity, Durham, North Carolina; Donald J. Carmichael, MD,

Umwrsizy of Alabama, Binnmgham, Alabama; Joseph M. Donald, Jr.,

-

MD, Thomas T. Donald, MD, William N. Viar, Jr., MD, AM1

Brookwood Medical Center, Birmingham, AtiatnLI; Donald J.

Carmichael, MD, Baptist Medical Cc?ntrr--I-‘rinsetc~~~. Birmingham, Alabama; Eugene R. Nobles, Jr., MD, Ba$sr Memuriul Hospital,

Memphis, Tennessee; Donald J. Carmichael, MD, Joseph M. Donald.

Jr., MD, Thomas T. Donald, MD, William N. Viar, Jr., MD, Ba@sc

Montclair Medical Cmtrr, Bimunghum. Alubamu; David A. Alhertson,

MD, Bowman Gray School of Medicine, Wmston-S&m, North Carolina; William Chalfant, MD, John N. Crook, MD, Cuhut-nns Memorial

Hospital. Concord, North Carolina; Charles M. Ferguson, MD, Crusvford

Long Hospital. Atlanta, Geor&; Elmo J. Cerise. MD, Gary E Gansat,

MD, Elmwotd Medical Center, _le&x~n, LUUIS~U~; Charles M.

Fetguson. MD, Emor)r University, Atlanta, G~‘trgiti; Edward M.

Copeland, MD, W. Robert Rout, MD, University of Florida, tiamewilfe, Florida: Steven Eubanks, MD, George Lucas, MD, J. Patrick Luke, MD,

Edward Mason, MD, Lucian Newman, 111, MD, l)a\rld M. Ruben, MD,

John I? Wilson, MD, Titus Duncan, MD, G*orgz Baptist Medical

Center, Atinca. Gewrgia; John S. Bolton, MD, John C. Bowen, MD,

William M.P McKinnon, MD, Daniel H. Hayes, ML), AtmandoSatdi,

MD, J. I’hihp Boudreaux, MD, Orhsner CLnis 8 Alron Ochsndr Medical

Foundation, New Orleans. Louisiana; David R. Baird, MD, Alton G.

Brown, MD, Robert S. Cathcart, MD, Harry B. Gregorir, ML), Telfait

H. Parker, MD, Henry C. West, MD, Roper and St. f+mcis Xaciar Hospitals, Charleston, South Curofina; Elmo J. Cerl>e, MD, Gary E

Gansar, Mt), St. Churlrs Gene& Hospital, New CGUE, Louisiana; Donald J. Carmichael. MD, Joseph M. Donald, Jr., Ml). Thornas T.

Donald, MD, Samuel l? Gillis, MD, William N. Viat, Jr., MD, St.

Vincent’s Hospital, Birmingham. Alabama; Wydn S. Beazley, III, MD,

Richard Claty, MD, Jamea R. L>arden, Jr., Ml), Stuilrt Circle Hospital,

Richmond, Vir@a; Elmo J. Cerise, MD, G,lry E Ciansar, ML). 7&o

In&na~. Nrw Orleuns. Louisiana; Elms J. Cenar, ML), Cry E Gansat,

MD, Tulane University Medical Center, New Or&u, Louisiana; Satkis

G. Aghazari,m, MD, Marn J. Fatha, MD, James C. Fuchs, MD, Joseph

H. Hooper, Jr., MD, Laurence H. Russ, MD, Fr,mcl S. R~~tolo. MD,

Union Memurial Hos@al, Baltimore, Maryland; William 0. Richards,

MD, John L. Sawyers, MD, Kenneth Sharp, ML,, Vunderbilt Uniaersity, Nashville, Tennessee; Janet Dis, PA, Stephen B. Edge, MD, Bruce D.

Schirmet, MD, University of Vqinia, Churlottesvil~, Virgmiu; William

J. Anderson, MD, Jeanne Batlinger, MD, Hexhe! A. Graves, Jr.. MD,

West.&, Bapast. Park&w, and Saint Thoma, Hurp~~ls, Nash%&, Tennessee; Michael E. Daugherty, MD, Thomas H. Greenlee, MD,

Karen Hillenmeyet, PA, Edwin J. Nighbert, ML>, John 13. &wart,

MD, Good Samaritan Hospital, Lexington, Kentucky; Joseph M. Donald,

Jr., MD, Thomas T. Donald. MD, William N. Viar, MD, He&h South Hospital, Birmingham, Alabama; George R. McSwain. MD. L. W. Blake

Memorial and Manatee Hospital, Br&ntutt, F&da; Chatlr~ M.

Fetguson, ML), Mussahwrttz Gmrxral Hospital, Bo,ton. Massachusetts; George Lucas, MD, John l? Wilson, MD, Mrdrsal (:ollfgia of Georgia,

Augusta, Georgia; Ehno J. Cerise, ML>, Gary E Gansar, ML), Mercy

Hospital, New @/enns, LozZana, Alexander J. Haick, Jr,, ML), A.

Michael Koury, MD, Albert L. Meena, MD, Anthony 8. Petro. MD,

C. Randle Voyles, MD, Misriwppi Baptist, Samr Dominic, and Riuer

Oaks Hospitals , h&m 1 Mississippi.

THE AMERICAN JOURNAL OF SURGERY@ VOLUME 170 JULY 1995 59

the learning curve for laparoscopic cholecystectomy.pdf

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