A New Method of External Cardiac Massage to Improve Diastolic Augmentation and PrGlong Survival Time

Transcription

1 A New Method of External Cardiac Massage to Improve Diastolic Augmentation and PrGlong Survival Time Takahira Ohomoto, M.D., Isamu Miura, M.D., and Souji Konno, M.D. ABSTRACT Experiments were performed on 5 dogs to determine the reason for unsatisfactory survival rates following closed-chest cardiac massage and to help develop new means for increasing survival following acute myocardial infarction and other causes of cardiac arrest. A new technique, named the countermassage method, was subsequently developed. Coronary and carotid flows after use of countermassage following cardiac arrest were increased 1.4 and 2 times, respectively, in contrast to flows obtained during manual closed-chest cardiac massage. These increases brought flows up to normal levels. We also tried to determine whether survival could be extended by this method to facilitate clinical treatment such as defibrillation or placing a temporary pacemaker catheter under fluoroscopic control, which are hard to accomplish during the brief time permitted by conventional closed-chest cardiac massage. The closed-chest cardiac massage method advocated by Kouwenhoven [51 is practical because it may be carried out in any place at any time by virtually anyone. It is widely applied during emergency cardiac resuscitation. A device based on the manual massage principle is currently being popularized, but survival with it has been unsatisfactory on the whole, and it seems to be least effective in ischemic heart disease [6,8,12]. Analysis of the unsatisfactory results with conventional cardiac massage techniques led us to develop a mechanical adaptation incorporating the principles of both the conventional mechanical method adapted from manual closed-chest massage and the machine used to compress the abdomen. A small device was constructed that improves the hemodynamics of coronary and carotid flow. The technique, which has been termed the countermassage method, consists of abdominal compression followed by chest compression of the standard type with the complete maneuver being carried out 7 to 9 times per minute. The abdomen is compressed between 78 and 82% of each cycle; the chest is compressed a quarter-cycle after abdominal compression begins and lasts 27 to 3% of each cycle. The sequence of compression is controlled automatically. Cardiac output during use of the countermassage device can be augmented to 3 times the levels obtainable through conventional mechanical or manual massage. Coronary and carotid flows can be improved 2 and 1.4 times, respectively, compared with flows obtained by conventional methods; these are equivalent to normal flows (Fig 1). The need for clinical treatment of circulatory insufficiency or arrest due to serious arrhythmia and ventricular fibrillation or to atrioventricular block accompanying acute myocardial infarction has increased greatly in the past twenty years. Successful administration of treatment such as defibrillation or pacing within the 15 minutes of resuscitation time permitted by the original closed-chest cardiac massage has been difficult. The countermassage method has added 15 to 2 minutes to this critical period. From The Heart Institute of Japan, Tokyo Women s Medical College, Tokyo, Japan. We gratefully acknowledge the assistance of Professor Kiichi Tsuchiya, Waseda Institute of Technology, in manufacturing the cardiopulmonary resuscitator discussed in our study. Accepted for publication Jan 7, Address reprint requests to Dr. Ohomoto, The Heart Institute of Japan, Tokyo Women s Medical College, 1 Kawadacho, Shinjuku-ku, Tokyo, Japan. Materials and Methods Fifty adult mongrel dogs weighing from 1 to 3 kg were anesthetized intravenously with pentobarbital (15 mg per kilogram of body weight). An endotracheal tube was inserted, and the dogs were ventilated with a positive- and negativepressure respirator. Ascending aortic pressure, 284

2 285 Ohomoto, Miura, and Konno Method of External Cardiac Massage *O r... n(-.. -j i i -.. Countermassage ; ; ; CONTROL CONVENTIONAL COUNTER- MASSAGE MASSAGE Fig I. Coronary and carotid flows by the countermassage method are 1% and9oo/ those of a natural cardiac beat, respectively, and are 2. and 1.4 timesgreater than flow rates attainable with manual or conventional mechanical massage. right atrial pressure, inferior vena caval pressure, carotid flow, left circumflex coronary artery flow, and cardiac contractions were determined. A flow probe was inserted to measure coronary flow, and in order to correct for the error due to change in position of the probe during massage, it was fixed to pericardium which lay vertical to the axis of the coronary arteries. Hemodynamic comparisons were made, and long-term hemodynamic function with the manual, conventional mechanical, and countermassage methods was measured (Fig 2). Prior to the experimental study, control values for cardiac function were recorded. Ventricular fibrillation was produced with 15 volts of direct current applied for 1 or 2 seconds using an electrode catheter inserted into the right ventricle through the femoral vein. In the control study, 5 dogs had massage for 3 minutes under optimal conditions that had been determined in advance for both the conventional mechanical and the countermassage machines (Table 1). Manual massage was administered by 3 persons alternating every 5 minutes to avoid individual fatigue. The compression frequency of both the conventional mechanical and countermassage machines was 7 to 9 cycles per minute. The compression time ratio for the conventional machine (time of compressionitime of compression and decompression, or SmlT) was.27 to.3. The compression time ratio of the countermassage machine (SclT) was.78 to.82. The compressive phase-shift angle of the countermassage machine to the conventional machine was -9 degrees. This indicates that for the most effective coronary and carotid flows, chest compression with the conventional machine should be started a quarter-cycle following compression of the abdomen (Fig 3). The compressive strokes of both the conventional and the countermassage machine averaged about 4 mm. Fig2. System of external cardiac nzassage fibrillating canine heart. fora Conventional Massage Machine I, Counter Massage Machine 1 1 Aortic Pressure... Venous Pressure--... Coronary flow.^^--- ECG. Carotid Flow... / / I essure Reaulator

3 ~~ 286 The Annals of Thoracic Surgery Vol 21 No 4 April 1976 Table 1. Optimal Driving Conditions for Cardiac Massage Machines Control Variables Driving frequency (cpm) SmiT SciT Driving phase-shift angle (degrees) Stroke of conventional machine (mm) Stroke of countermassage machine (mm) Counter position Optimal Conditions Abdomen SmlT = compression time ratio for conventional massage machine; SciT = compression time ratio for countermassage machine (see text for explanation). Cardiac stimulants were used to compare the long-term hemodynamic effects of each method. A solution combining 1 ml of lactated Ringer's, 1 ml of 7% sodium bicarbonate injection, and 1 mg of epinephrine was injected directly into the right atrium,.2 mlikgimin during the manual and conventional mechanical massages and.4 ml/kg/min during countermassage. After a 3-minute massage, 1 to 2 wattseconds of D-c defibrillation was applied, and supplementary massage was carried out if additional shocks were necessary. Results The hemodynamics of each 3-minute massage are shown in Figure 4. With manual massage, lack of hemodynamic stability was noted which Fig3. For the most effective hemodynamics, compression by the conventional machine should be started one quarter-cycle following compression of the abdomen. ABDOMINAL COMPRESSOR \hest compression V one cycle t (bdominal compression (a quarter-cycle before chest compression) (Phase shift -9" " t9" +18 t27 A was largely attributable to operator fatigue. Coronary and carotid flows dropped substantially within 1 to 15 minutes. The cardiac output was limited to a third to a quarter of normal due to regurgitation of cardiac blood to the venous system through valves deformed during compression [lo]; the peak aortic pressures were high, but mean aortic pressures were low. For the first 15 minutes after massage was begun, mean aortic and venous pressure differences were minimal. Afterward venous pressure began to show an inverse relationship to mean aortic pressure and eventually rose to 2 times the control value, indicating that manual massage was ineffective after 15 minutes. Figure 4 also shows the effect of the conventional mechanical massage machine For the first 15 minutes hemodynamics were stable, with a slight difference between aortic and venous pressures. However, after 15 minutes coronary and carotid flows decreased just as with manual massage, and the effects were ultimately the same. In the countermassage method, hemodynamic function was satisfactory throughout the 3-minute period of application. Coronary and carotid flows approximated the control value of a normal cardiac beat. Although venous pressure was relatively high (4 mm Hg), the aortic-venous pressure difference was kept above 15 mm Hg, which means that circulation was achieved under stable conditions. The long-term hemodynamics of closed-chest massage combined with cardiac stimulants are shown in Figure 5. Note that hemodynamic function after defibrillation was unstable during manual massage (Fig 5a). It is also worth mentioning that while blood pressure rose initially

4 287 Ohomoto, Miura, and Konno Method of External Cardiac Massage.- C. 5!i f14h E E1 l - 12 U - - c " - 1 P12 - E loot 6 a I t 9\ Manual massage Duration of massage (rnin) Conventionol Mossoge Duration of massage (rnin) Counter massage 1 O K I I I I I Duration of massage (rnin) Fig4. Hemodynamic effects of each type of massage in the same animal. With the countermassage method, mean aortic and carotid flo7os uiere improvedto about double the levels with manual massage. after defibrillation due to the effects of the stimulating agents, this did not last. After 8 minutes, on the average, all the dogs died from congestion in various internal organs (especially the liver and hearf muscle) as shown by postmortem examination. Hemorrhage in lung tissue was also noted. Hemodynamic data up to the twenty-seventh day from animals resuscitated by the conventional mechanical method are shown in Figure 5b. Three of 5 dogs had died from pulmonary hemorrhage and 1 other dog was noted at postmortem examination to have slight congestion in both liver and lung. All 5 dogs undergoing countermassage survived. The hemodynamic data on these dogs after 9 days' survival are shown in Figure 5c. In these animals, hemodynamic data during the 3 minutes of massage and after defibrillation were approximately equal to control values. Survival studies on the dogs treated with drugs are detailed in Table 2. The results of another group of studies on survival after defibrillation are shown intable 3. So that the effects of massage alone could be ascertained, no pharmacological agent was used in this group during any massage. In the group receiving manual massage we succeeded in defibrillating 2 dogs after 3 minutes of massage, but the other 3 could not be successfully defibrillated. With conventional mechanical massage, 2 of 3 dogs developed bradycardia and a prolonged QRS time; both died after several minutes of attempted supplementary massage after defibrillation. From these results we concluded that longterm massage using the manual or conventional mechanical methods is not effective and that survival can only be accomplished within the first 15 minutes of massage. Defibrillation should be carried out as quickly as possible. In our experience, survival exceeding 15 minutes among humans with a fibrillating heart, especially when accompanied by acute myocardial infarction, has been extremely rare. With the countermassage technique, despite 4 minutes of massage, 5 of 6 animals were successfully defibrillated and for the most part stabilized after defibrillation. In another set of experiments, each kind of massage was carried out for 5 minutes in the same animal. In spite of the fact that manual and conventional mechanical massage were carried out under the relatively favorable conditions present just after fibrillation, the hemodynamic results obtained were poor. By contrast, during the countermassage period both mean aortic and carotid flows were improved to about double the levels with manual massage, even though countermassage was not started until after this group

5 288 The Annals of Thoracic Surgery Vol 21 No 4 April (a) Manual massage Time (rnin) 6 21 (b) Conventional Massage L E - - -conv~ -i iwr L E\ I I \ 251 Time Time (min) (min) Fig 5. Hemodynamics of long-term survival studies using cardiac stimulants (a) Manual massage was ineffective, and all animals died with severe congestion of various internal organs. (b) Animals receiving conventional mechanical massage showed slight improvement, with 3 of 5 dying from pulmonary hemorrhage. (c) With the countermassage technique all 5 animals survived. On the ninth day 1 was killed for histological examination. had already undergone two other forms of massage and had experienced 1 minutes of poor circulation. Comment The closed-chest cardiac massage recommended by Kouwenhoven [51 in 196 has been the most practical method of preparation for defibrillation up to this point, primarily because it is the only one designed especially for use outside the hospital. However, Stephenson's study [91 of 5,76 patients from 5 facilities revealed that only 819 survived, a rate of 16%. The primary factor in successful resuscitation is the amount of time that has elapsed before resuscitation begins. When more than 4 minutes have passed since the moment of circulatory arrest, Stephenson showed that the survival rate with either closed or open cardiac massage is only 4%. It is therefore absolutely necessary to start cardiac resuscitation within 3 minutes; after this time irreversible changes begin to occur in the brain. The cardiac muscle itself will not undergo irreversible changes for about 1 to 15 minutes, which means that if cerebral circulation is adequately maintained, cardiac massage can prolong the survival time from 3 to 15 minutes before defibrillation is accomplished. The next most important factor in resuscitation is the environment where it is carried out. According to Stephenson [9] the survival rate is relatively high (5%) in the closely controlled atmosphere of places such as the operating room, intensive care unit, and coronary care unit; but it is as low as 21% in other parts of the hospital and drops even further outside the facility. If a patient begins to fibrillate outside the hospital, it is most difficult to transport and defibrillate him within 15 minutes, and an alternative way to prolong survival time is needed. Survival depends largely upon the kind and severity of the causative disease. The survival rate in ischemic heart disease with acute myocardial infarction is as low as 14% even when the patient is treated in an optimal environment like the coronary care unit, according to William and William [12] and Miura [6]. Eliot and Vyden [21 showed that cardiac arrest can be caused by the downward displacement of a cardiac pacemaker (electrical failure), decrease of cardiac contractility (power failure), or hypoxia caused by hypoventilation. It is evident that cardiac arrest is induced by coronary insufficiency, and the existing hypoxia of cardiac muscle makes it difficult to survive this condition. In ischemic heart disease, then, the time limit

6 289 Ohomoto, Miura, and Konno Method of External Cardiac Massage Table 2. Survival Studies Using Drugsa in 15 Dogs Drug Inject. Sex & Massage Speed Weight Time Method (mlikgim in) (kg) (min) Result Manual.2 M, 19 3 Died (3 hr) massage M, 15 Died (1 hr) F, 12 Died (defib) M, 17 Died (3 hr) M, 26 Died (1 hr) Conventional.2 M, 23 3 Died (1 hr) massage M, 12 Died (Ih hr) M, 18 Killed (12 days) M, 2 Killed (27 days) M, 2 Died (1 day) Counter-.4 M, 15 3 Killed (9 days) massage M, 2 Killed (3 days) M, 2 Killed (1 days) M, 17 Killed (5 days) M, 2 Alive (more than 1 yr) Solution consisting of 1 ml of lactated Ringer s, 1 ml of 7% sodium bicarbonate injection, and 1 mg of epinephrine. within which resuscitation can be accomplished is less than 15 minutes, and greater emphasis must be placed on maintaining cerebral and coronary circulation. Closed-chest cardiac massage is not adequate to keep circulation stable because it cannot control the low cardiac output induced by regurgitation of cardiac blood into the venous system. Pulse pressure is minimal after 15 minutes and circulatory volume decreases rapidly, thus leading to cardiac shock. In addition, this method cannot selectively maintain coronary circulation. In management of ventricular fibrillation, then, the first problem is to mechanize the massage procedure in order to achieve hemodynamic stability. The second step is to increase coronary circulation selectively through diastolic augmentation. Because it incorporates principles from both the conventional mechanical machine, adapted from manual closed-chest massage, and the massage machine that compresses the abdomen, the countermassage method fulfills both needs. In dogs, hemodynamic stability can be main- Table 3. Results of Resuscitation Using Massage Alone in 14 Dogs Weight Duration of Method (kg) Massage (min) Result Manual massage Cardiac arrest 3 3 Successful defib 23 3 Successful defib Pulmonary edema-arrest 8 3 Cardiac arrest Conventional massage 17 3 Successful defib 18 3 Brad ycardia-arrest 12 3 Bradycardia-arres t Countermassage 25 4 Successful defib 17 3 Bradycardia 15 4 Successful defib 14 4 Successful defib 2 3 Successful defib 13 3 Successful defib

7 29 The Annals of Thoracic Surgery Vol 21 No 4 April 1976 tained for only about 15 minutes using manual or conventional mechanical massage, while it can be supported for as long as 3 to 4 minutes during countermassage. Countermassage also keeps the pulse pressure constant at 15 mm Hg. Pantridge [71 has stated that 6% of acute myocardial infarctions are accompanied by complete atrioventricular block and ventricular arrest within 12 hours. Chiocca [ll has stated that the incidence of ventricular arrest due to ventricular fibrillation is 74%. In 194 Wigger [ll] and Gurevich and Yuniev [3] suggested that the maximum time for defibrillation and reestablishment of the cardiac beat is from 1 to 1% minutes but can be prolonged to 8 minutes when closed-chest cardiac massage is carried out before defibrillation. Hosler [4] asserted that it is necessary to limit the time of defibrillation strictly and mentioned that cardiac massage should be done before a defibrillation of more than 5 seconds in order to augment the coronary circulation. In our experimental studies of defibrillation that sought to improve the extreme bradycardia or atrioventricular block usually present just after this event, supplementary countermassage was carried out for 1 to 2 minutes with 5% of the drive ordinarily used in the countermassage technique. The cardiac beat was shortly reestablished in sinus rhythm. References 1. Chiocca JC Cardiac arrest complicating acute myocardial infarction. Med Ann DC 33411, Eliot C, Vyden JK Resuscitation after myocardial infarction. JAMA 29, Gurevich NL, Yuniev GS Restoration of regular rhythm in mammalian fibrillating heart. Annu Rev Soviet Med 3236, Hosler RM Cardiac resuscitation. Biochem Clin 1327, Kouwenhoven WB Closed chest cardiac massage. JAMA , Miura I A review of 27 cases of acute myocardial infarction. Jpn Heart J 212, Pantridge JF Cardiac arrest after myocardial infarction. Lancet 187, Pierce JA Cardiac arrest and deaths associated with anesthesia. Anesth Analg (Cleve) 4547, Stephenson HE Cardiac Arrest and Resuscitation. St Louis, Mosby, Tsuchia KI, Tanabe TK Studies of the cardiac massage machine (11). Rep Waseda Inst Tech (Japan) 5812, Wigger CJ The physiologic basis for cardiac resuscitation from ventricular fibrillation method for serial defibrillation. Am Heart J 2413, William JG, William FM Resuscitation for cardiac arrest due to myocardial infarction. Dis Chest 5173, 1966 Editor s Note Dr. Ohomoto and his colleagues have stated that the likelihood of human survival after more than 15 minutes of manual or conventional mechanical resuscitation is very small. While the improved perfusion accomplished by the authors with the countermassage technique is certainly desirable, experience with closed-chest cardiac resuscitation in the United States suggests that properly administered resuscitation can be carried out for considerably longer than 15 minutes with hope of survival.