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overhydration, systemic sepsis, oral-gastrointestinal contamina- tion, anemia, supine positioning, oxygen toxicity, and barotrau- ma. But mortality persists, and the patient who gets to the stage of 100% oxygen and high airway pressure despite and after our best efforts is sicker now than the same patient in 1973. From

Extracorporeal Membrane Oxygenation Revisited, Revisited To the Editor:

In an editorial referring to our report on extracorporeal life support in adult respiratory failure (ARF), Bosken and Lenfant [l] point out that many things have changed in the 18 years since the NHLBI-sponsored adult extracorporeal membrane oxygenation (ECMO) study was designed. We agree; this is why we con- ducted the phase I-safety and efficacy-"ECMO Revisited clinical experience reported in this issue of The Annals [2]. Bosken and Lenfant comment that research on extracorporeal life sup- port (ECLS) should be based on carefully designed protocols incorporating modem understanding of pulmonary pathophysi- ology, supportive treatment, and ECLS technology. They argue that reference to the 1974 to 1979 NHLBI ECMO study [3] is outdated, and the current mortality risk of the 1973 selection criteria is unknown. We agree, and included this discussion in our manuscript. However we welcome the opportunity to pro- vide further commentary.

Gattinoni and Kolobow [5] we learned (hat the ventilator man- agement in ECMO-treated patients in the NHLBI study was all wrong. Why go to all the trouble and risk of extracorporeal support, then leave the patient at high O2 and airway pressure? The same investigators suggest that the use of venoarterial (rather than venovenous) bypass might have contributed to lung injury. They reported 50% survival, and others have corrobo- rated their report. From the experience with ECMO in newborn infants and children we learned that survival is more than 90% in patients with reversible disease, that bleeding should be a rare complication, that devices for ECLS are safe and reliable during weeks of continuous use, and that successful management of ECLS requires a large and well-trained team. There was reason to believe that ECLS should be revisited. Bosken and Lenfant agree that reevaluation of adult ECLS is appropriate. The questions are: how to select moribund but salvageable patients for phase I studies, and when to design and fund phase I1 prospective, randomized trials?

The answer to .the first question is realistically simple. No matter what physiologic criteria are used-even with correlative mortalitv data from that institution or from the literature-the

See also pages 551 and 553.

How should a new high-technology treatment proceed from laboratory to clinical study to clinical practice? This was the topic of an NIH workshop conducted in June 1990 using the diffusion of ECMO for neonatal respiratory failure as an example [4]. Neonatal ECMO began with laboratory development and de- pends on continuous refinement through basic research. Phase I clinical trials in moribund infants were conducted until (1) the technique was stable and standardized, (2) relative risk and safety were documented, and (3) results allowed formulation of a hypothesis for a phase I1 evaluation. Two prospective, random- ized (phase 11) trials were done in centers with preliminary experience in more than 50 cases. A phase I11 prospective, randomized trial demonstrated improved cost-effectiveness com- pared with other contemporary therapy. This research on neo- natal ECMO has been sponsored by the NIH since 1972. A record of all cases (now more than 6,000) is maintained in a central Registry, documenting patient characteristics, risk and safety, and growth of the technology as dinical research became clinical practice. Our research group was responsible for much of the neonatal ECMO research, and we are following the same se- quence in the reevaluation of ECLS in adult and pediatric respiratory failure.

We participated in the 1974 to 1979 NHLBI adult ECMO study design and implementation. That was a benchmark project because it was the first prospective, randomized study of a life support technique in which the end point was death. There were many problems with the study [5], but we learned many lessons: Characterize the patient population and results of standard treatment first. Conduct the study only in centers that are very experienced with both standard and experimental treatment. Use a randomization design that minimizes the logistical and ethical dilemmas. Assure enough diversity of patients that the study will not be dominated by a single patient group. Stop the study when one treatment is clearly better, or when there is clearly no difference. All of these concepts were applied to the development of neonatal ECMO including the design of the prospective, randomized studies of life support.

It was appropriate to stop the 1974 to 1979 study prematurely, and the results and conclusions were accurate and appropriate. Why, then, are we revisiting adult ECMO now? For all the reasons that Bosken and Lenfant enumerate, and more. Modern understanding of lung injury, recovery, and supportive treat- ment has definitely improved both prevention and outcome in severe respiratory failure. We have learned to avoid or treat

skepticai reader will argue that the patient might have survived with better conventional therapy (preferably in his or her own institution). The 1974 NHLBI ECMO entry criterion is as good or as bad as any, and it has been used (and reverified) consistently over many years. When the parameters are measured after and despite all appropriate treatment, patients with high mortality risk are identified. That is the only purpose of selection criteria for a phase I study, and as long as the preintervention treatment and patient characteristics are described, anyone can repeat the study. We reported that 4 patients who met our entry criteria but were not treated with ECLS all died, but the skeptical reader would appropriately argue that our care was inadequate. We can only ask the reader to trust that our conventional management of adult respiratory failure is as good as his or hers.

The second question is more challenging, and we addressed it in our discussion. Another prospective, randomized study of adult ECLS should be done when both ECLS and conventional treatment are standardized and characterized; in a center or centers with experience with 50 ECLS patients; when mortality and morbidity risk with standard treatment is well characterized; and when an adequate diversity of salvageable patients can be assured.

In the meantime, based on reported experience with more than 400 patients in the modem era, we know that the survival of adult respiratory failure treated with ECLS is at least 50%. This is better than the results of any other treatment with a survival of, say, 20%. This experience is corroborated in our own phase I trial reported in this issue. Therefore we describe ECLS as extraordi- nary but appropriate (not experimental) treatment for patients with reversible respiratory failure when the treating physician believes (based on the best measurements available) that the chance of survival is less than 20%. Robert H . Bartlett, M D Harry L . Anderson I l l , M D The University of Michigan Medical Center 2920 Taubman Health Care Center 1500 E Medical Center Dr Ann Arbor, MI 48109-0331

References 1. Bosken C, Lenfant C. Extracorporeal membrane oxygenation

2. Anderson HL 111, Delius RE, Sinard JM, et al. Early experience revisited . . . again. Ann Thorac Surg 1992;53:551-2.

0 1992 by The Society of Thoracic Surgeons Ann Thorac Surg 1992;73842 0003-4975/92/$5.00

Ann Thorac Surg 1992;53:73842

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with adult extracorporeal membrane oxygenation in the mod- ern era. Ann Thorac Surg 1992;53:553-63.

3. NHLBI-NIH. Extracorporeal support for respiratory insuffi- ciency. DHEW Publication, 1980.

4. Wright L. NIH Workshop on Neonatal ECMO and Diffusion of Technology. NIH/NICHHD (in press).

5. Gattinoni L, Pesenti A, Mascheroni D, et al. Low frequency positive pressure ventilation with extracorporeal CO, removal in severe respiratory failure. JAMA 1986;256:881-5.

Esophagogastrectomy for Acid Injury To the Editor:

In their article on emergency esophagogastrectomy for corrosive injury, Horvlth and collaborators [ l ] wrote that damage to the stomach is generally observed in the antrum and fundus, but acute necrosis usually affects the major part of the stomach and is only very rarely cured by partial resection. This has been our experience, too. They added that they always perform total esophagogastrectomy and the esophagus is resected without a thoracotomy. We behave differently concerning the esophagus

In a group of 80 patients treated for severe corrosive esopha- gogastric burns, total gastrectomy had to be performed in 20 patients because of necrosis and perforation. It was done within 24 hours in 12 patients: 5 had ingested an acid (2 >150 mL, 2 4 5 0 mL, 1 unknown quantity), 4 had ingested a base (1 >150 mL, 1 <150 mL, 2 unknown quantities), 2 had ingested bleach (>150 mL), and 1 had ingested formaldehyde (<150 mL). Gastrectomy was done between postinjury days 1 and 20 in 8 patients: 1 had ingested an acid (<150 mL), 3 had ingested a base (2 >150 mL, 1 unknown quantity), and 4 had ingested bleach (>150 mL). The duodenum, cardia, and cervicothoracic esopha- gus were hand-sutured. A terminal cervical esophagostomy and a feeding jejunostomy were performed.

Five of the 20 patients died in the postoperative period: of multiple small bowel perforation on day 9, of peritonitis on day 18, of systemic sepsis on days 2 and 18, and of a tracheoesoph- ageal fistula on day 33. The 15 survivors had a second-stage retrostemal colon interposition bypassing the excluded esopha- gus. One died of complications of an esophageal mucocele at 4 years, 4 were found to have a nonsymptomatic small esophageal mucocele, and 1 had a regressive mucocele.

When necrosis from ingestion of caustic material is present in the abdomen, aggressive operation is often necessary [3]. If the burns extend to the bowel and pancreas, extended resections with delayed sutures and with enterostomies offer the only chance of cure. What is to be done with the esophagus is more debatable: esophagojejunal anastomosis may be attempted in a small minority of well-selected cases, the esophagus can be sutured over a drain, it can be closed at both ends and excluded, or it can be resected.

Blind resection is easy but may be unnecessary, and it may provoke a tear in the membranous part of the trachea. It has been advocated to stop extensive necrosis of the esophagus from reaching the trachea. However its mortality is high [4, 51. Those who resect the esophagus as a preventive measure also state that if endoscopy discloses necrosis of the trachea, one should refrain from performing an esophagectomy.

In our series, all the patients who died had an autopsy. The esophagus was not the cause of death except in the case of the patient with a tracheoesophageal fistula that appeared on day 33: this was the only failure of exclusion. Two patients underwent emergency bronchoscopy because of respiratory disorders asso- ciated with stage 111 esophageal burns: 1 of them had a white area

PI.

on the posterior surface of the trachea and left bronchus, and 1 had no lesion. They both recovered. The excluded esophagus did not invite immediate danger in our experience, but it could produce a secondary mucocele (which was retrospective proof it was not very deeply burned, as endoscopy generally overesti- mates the lesions). So we suggest immediate exclusion of the esophagus in the majority of cases to avoid the supplementary trauma of resection, with subsequent esophagectomy during coloplasty to prevent the formation of a mucocele [6].

Michel E . Ribet, M D

HSpital Calmette F . 59037 Lille Cedex France

References 1.

2.

3.

4.

5.

6.

Horvlth OP, Ollh T, Zentai G. Emergency esophagogastrec- tomy for treatment of hydrochloric acid injury. Ann Thorac Surg 1991;52:98-101. Ribet M, Chambon JP, Pruvot FR. Oesophagectomy for severe corrosive injuries: is it always legitimate? Eur J Cardiothorac Surg 1990;4:347-50. Gago 0, Ritter FN, Martel W, et al. Aggressive surgical treatment for caustic injury of esophagus and stomach. Ann Thorac Surg 1972;13:243-50. Gossot D, Sarfati E, Celerier M. Early blunt esophagectomy in severe caustic burns of the upper digestive tract. J Thorac Cardiovasc Surg 1987;9418%91. Hwang TL, Shen-Chen SM, Chen MF. Nonthoracotomy esophagectomy for corrosive esophagitis with gastric perfora- tion. Surg Gynecol Obstet 1987;164:53740. Mannell A, Epstein B. Exclusion of the esophagus: is this a dangerous manoeuvre? Br J Surg 1984;71:442-5.

Severe Endobronchial Hemorrhage To the Editor:

In a recent article, Purut and co-workers [ l ] described a case of severe endobronchial hemorrhage during a coronary artery by- pass operation due to pulmonary artery perforation by a Swan- Ganz catheter. The authors are to be commended for their successful and innovative use of an endobronchial balloon cath- eter without subsequent pulmonary resection to control the bleeding, but neither their report nor the accompanying discus- sion commented on the actual need for a Swan-Ganz catheter in their patient. In view of the recognized danger and expense of the Swan-Ganz catheter, it seems pertinent to question its use in a 64-year-old man with no recent infarction and normal cardiac function (ejection fraction 0.67) who was undergoing an opera- tion described as ”elective.” Unfortunately, Swan-Ganz catheters are often inserted by anesthesiologists without the surgeon’s advice or consent, as may have occurred in Purut and co- workers’ patient.

It is important to report complications related to Swan-Ganz catheters to document that use of a Swan-Ganz catheter is not innocuous and should not be routine. Information about cardiac output is rarely necessary intraoperatively in low-risk patients after coronary bypass, because such patients should not require inotropic support to be weaned from cardiopulmonary bypass [2, 31. (A Swan-Ganz catheter can always be inserted postopera- tively if circumstances change.) Information about left ventricular filling pressures is useful, however, and can be easily and inexpensively obtained by inserting a left atrial pressure moni- toring catheter. For the vast majority of surgeons who vent the