Direct Mechanical Ventricular Actuation for Resuscitation

human studies did not show clinically important changes in gas exchange or pulmonary hemodynamics as a result of sclerotherapy: 20.21 Thus, it is not clear that variceal sclerotherapy causes adult respiratory-dfstress syndrome; if it does, it appears to do so rarely. Variceal sclerotherapy is a widely used, effective therapy which causes a variety of pleural, pulmonary and Bacon 10 will be very helpful to clinicians who must evaluate patients with abnormalities related to this procedure. Alfred F. Connors, t-; M.D., F.C.C.R Cleveland Department of Medicine, Case Western Reserve University; Director, Medical Intensive Care Unit, MetroHealth Medical Center.

REFERENCES

1 Johnston G~ Rodgers HW A review of 15 years experience in the use of sclerotherapy in the control of acute haemorrhage from oesophageal varices. Br J Surg 1973; 60:797-800 2 Terblanche J, Northover JMA, Bornman ~ Kahn D, Barbezat GO, Sellars SL, et ale A prospective evaluation of injection sclerotherapy in the treatment ofacute bleeding from esophageal varices. Surgery 1979; 85:239-45 3 Kjaergaard J, Fischer A, Miskowiak J, Lindahl F, Baden H. Sclerotherapy of bleeding esophageal varices: long-term results. Scand J GastroenteroI1982; 17:363-67 4 MacDougall BRD, Westaby D, Theodossi A, Dawson JL, Williams R. Increased long-term survival in variceal haemorrhage using injection sclerotherapy: results of a controlled trial. Lancet 1982; 1:124-27 5 The Copenhagen Esophageal Varices Sclerotherapy Project. Sclerotherapy after first variceal hemorrhage in cirrhosis: a randomized multicenter trial. N Engl J Med 1984; 311:15941600 6 Potzi R, Bauer ~ Reichel ~ Kerstan E, Renner F, Gangl A. Prophylactic endoscopic sclerotherapy of oesophageal varices in liver cirrhosis. A multicentre prospective controlled randomised trial in Vienna. Gut 1989; 30:873-79 7 Cello J~ Grendell JH, Crass RA, Trunkey DD, Cobb EE, Heilbron DC. Endoscopic sclerotherapy versus portacaval shunt in patients with severe cirrhosis and variceal hemorrhage. N Engl J Med 1984; 311:1589-94 8 Cello J~ Grendell JH, Crass RA, Weber TE, Trunkey DD. Endoscopic sclerotherapy versus portocaval shunt in patients with severe cirrhosis and acute variceal hemorrhage: long-term follow-up. N Engl J Med 1987; 316:11-5 9 Henderson JM, Kutner MH, Millikan WJ, Galambos JT, Riepe S~ Brooks WS, et ale Endoscopic variceal sclerosis compared with distal splenorenal shunt to prevent recurrent variceal bleeding in cirrhosis. Ann Intern Med 1990; 112:262-69 10 Edling JE, Bacon BR. Pleuro-pulmonary complications of endoscopic variceal sclerotherapy. Chest 1991; 99:1252-57 11 Stroncek DF, Hutton S~ Silvis SE, Vercellotti GM, Jacob HS, Hammerschmidt DE. Sodium morrhuate stimulates granulocytes and damages erythrocytes and endothelial cells: probable mechanism of an adverse reaction during sclerotherapy. J Lab Coo Med 1985; 106:498-504 12 Cacciola E, Giustolisi R, Musso R, Vecchio R, Longo A, Triolo A, et ale Activation of contact phase of blood coagulation can be induced by the sclerosing agent polidocanol: possible additional mechanism of adverse reaction during sclerotherapy J Lab Clin Med 1987; 109:225-26

13 Evans DMD, Jones DB, Cleary BK, Smith PM. Oesophageal varices treated by sclerotherapy: a histopathological study. Gut 1982; 23:615-20 14 Sales BJ,Kilby AE, Deitrich PA, Coffin LH, Krawitt EL. Pleural and mediastfnal changes following endoscopic injection sclerotherapy of esophageal varices. Radiology 1983; 149:639-42 15 Schuman BM, Beckman ~ Tedesco FJ, Griffin J"W: Assad RT. Complications of endoscopic injection sclerotherapy: a review. Am J GastroenteroI1987; 82:823-30 16 Bacon BR, Bailey-Newton RS, Connors AF. Pleural effusions after endoscopic variceal sclerotherapy Gastroenterology 1985; 88:1910-14 17 Bacon BR, Camara DS, Duffy MC. Severe ulceration and delayed perforation of the esophagus after endoscopic variceal sclerotherapy. Gastrointest Endose 1987; 33:311-15 18 Monroe ~ Morrow CF, Millen JE, Fairman ~ Glauser FL. Acute respiratory failure after sodium morrhuate esophageal sclerotherapy Gastroenterology 1983; 85:693-99 19 Connors AF, Bacon BR, Miron SD. Sodium morrhuate delivery to the lung during endoscopic variceal sclerotherapy Ann Intern Moo 1986; 105:539-42 20 Bailey-Newton RS, Connors AF, Bacon BR. Effect of endoscopic variceal sclerotherapy on gas exchange and hemodynamics in humans. Gastroenterology 1985; 89:368-73 21 Camara DS, Caruana JA, Chung RS, Amodeo DJ. The hemodynamic effects of the sclerosant sodium morrhuate. Surg Gyn Obstet 1985; 161:327-31

Direct Mechanical Ventricular Actuation for Resuscitation How Should Efficacy Be Tested? advances in emergency care, survival rates D espite from cardiac arrest remain Standard exter-

low nal cardiopulmonary resuscitation (CPR) produces low cerebral and coronary perfusion pressures and flows, Open-chest CPR produces more physiologic pressures and flows, Despite its physiologic superiority, openchest CPR has not been widely applied. The article by Anstadt et al in this issue of Chest (see page 86) demonstrates that use of direct mechanical ventricular actuation (DMVA) during resuscitation from cardiac arrest can be accomplished rapidly and safely: This device provided better hemodynamic support than manual open-chest CPR. Unfortunately; there were no long-term survivors. Considering the extremely long periods of CPR prior to initiation of DMVA (40-114 minutes), this outcome is not surprising. In previous studies, cardiac arrest victims who required more than 30 minutes of external CPR rarely survived and the survivors often had neurologic deficits. 1•2 The delay in initiating DMVAwas apparently caused by waiting to obtain informed consent. Consent for resuscitation research has sparked debate among investigators and ethicists. Two factors complicate this issue: 1) resuscitation research involves comatose patients, and 2) these patients have life-threatening conditions that require immediate interventions to CHEST I 100 I 1 I JUL'f, 1991

3

prevent death or disability Any delay in therapy while awaiting consent can jeopardize the patient's chance of survival. In addition, families are often not available for consent or are too distraught to be objective. Under the "emergency exception to informed consent" of the United States Food and Drug Administration, consent may be waived in life-threatening situations when there is no better alternative. Based on these considerations, Abramson et al3 proposed the use of "deferred consent" for resuscitation research. They proposed that, under specific conditions, experimental treatment could be initiated prior to obtaining consent but within a reasonable time period "deferred consent" should be obtained. Since the treatment has already been initiated, "deferred consent" in fact is consent to continue therapy and to participate in the clinical trial. Experience with deferred consent in the Brain Resuscitation Clinical Trial II has demonstrated that families were satisfied with this approach." Anstadt et al agree that use of deferred consent could decrease the time required to initiate D MVA during cardiac arrest and thereby lead to more favorable outcomes. The fact that there were no survivors in this study should not imply that DMVA does not have a potential role in cardiac resuscitation. What should this role be in CPR-resistant cardiac arrest cases, particularly vis-a-vis other CPR alternatives, eg, cardiopulmonary bypass (CPB)? Certainly, for DMVA to be beneficial it needs to be employed earlier. The first logical step would be a trial employing D MVA in patients who do not respond quickly, ie, within lOIS min, to routine CPR-advanced life support (ALS), but have a good chance of benefitting from DMVA. We are currently conducting such a feasibility trial of CPB in 15 to 60-year-old patients who have suffered a witnessed cardiac arrest and who have had less than 6 min of no flow (arrest without CPR) and less than 30 min ofCPR-ALS. Although DMVA can provide similar hemodynamics,S CPB does not require a thoracotomy. Furthermore, CPB can control temperature and blood composition as well as reperfusion pressure and flow 6 This may be critical if other therapies are added, such as hypothermia, hemodilution, or brain-resuscitating drugs with cardiovascular depressant side effects. On the other hand, CPB requires a blood-artificial surface interface, systemic anticoagulation (not with heparinbonded systems," however), and vascular access, all of which may be difficult during CPR. In addition, the nonpulsatile flow generated by CPB may be less desirable than the pulsatile flow obtained with D MVA. 8 As clinical feasibility trials progress, a comparative trial may be indicated to determine the relative advantages of these interventions during resuscitation. Both CPB and DMVA offer advantages over standard CPR-ALS that may allow successful resuscitation 4

of patients who remain pulseless despite standard CPR-ALSo In the future, both may have specific roles in our resuscitation armamentarium. Samuel A. Tisherman, M. D.; and Norman S. Abramson, M.D. Pittsburgh International Resuscitation Research Center, Departments of Surgery and Anesthesiology/Critical Care Medicine, Presbyterian University Hospital. REFERENCES

1 Brain Resuscitation Clinical Trial I Study Group. Neurologic recovery after cardiac arrest: Effect of duration of ischemia. Crit Care Med 1985; 13:930-31 2 Pionkowski RS, Thompson BM, Gruchow H~ Aprahamian C, Darin J. Resuscitation time in ventricular fibrillation- A prognostic indicator. Ann Emerg Med 1983; 12:733-38 3 Abramson NS, Meisel A, Safar E Deferred consent: A new approach for resuscitation research. JAMA1986; 255:2466-71 4 Abramson NS, Safar ~ Brain Resuscitation Clinical Trial II Study Group. Deferred consent: Use in clinical resuscitation research. / Ann Emerg Med 1990; 19:781-84 5 Anstadt M~ Hendry PJ, Plunkett MD, et ale Mechanical cardiac actuation achieves hemodynamics similar to cardiopulmonary bypass. Surgery 1990; 108:442-52 6 Safar ~ Abramson NS, Angelos M, et al. Emergency cardiopulmonary bypass for resuscitation from prolonged cardiac arrest. Am J Emerg Med 1990; 8:55-67 7 Bindslev L, Eklund J, Norlander 0, et ale Treatment of acute respiratory failure by extracorporeal COl elimination performed by surface heparinized artificial lung. Anesthesiology 1987; 67:117-20 8 Sanderson JM, Wright G, Sims FW: Brain damage in dogs immediately following pulsatile and non-pulsatile blood Bows in extracorporeal circulation. Thorax 1972;27:275-86

Biomedical Ethics in the 1990s Biomedical ethics came of age in the 1980s. In 1976, the Quinlan case heralded the necessity for actively dealing with life and death issues when confronted with hopelessly ill patients on life support. 1 In 1983, the President's Commission for the Study of Ethical Problems in Medicine and Biomedical Research presented their extensive and ground breaking report to the nation. 2 Concurrently, physicians, lawyers, and scholars began to develop a rapidly growing literature examining old, new and future potential ethical problems.P" However, the biomedical technology of the 1980s has progressed so rapidly that, wherever we turn, we are faced with novel and highly complex ethical quandaries: the use of human fetal tissue, gene therapy in man, genetic alteration of nonhi-man species, and newer approaches to in vitro fertilization. Besides trying to respond to advances in biomedical technology, we remain conflicted over older and equally profound ethical dilemmas: the role of abortion, use of animals in education and research, relieving suffering with powerful analgesics in irreversibly; gravely impaired patients which might hasten Editorials