Circulatory assist techniques in cardiogenic shock: metabolic aspects

Assisted circulation in severe cardiogenic shock was evaluated using a reservoir and a single pump without an oxygenator in 88 dogs. Study groups included: no treatment, substrates only (cysteine, ribose), nitroprusside, left ventricular (LV) + right atrial (RA) bypass + substrates, LV + RA bypass, left atrial (LA) + RA bypass, LA bypass, LV bypass, LV + RA + fluosol. Metabolic studies of O2 consumption, acid and alkaline phosphatase, lactate, creatine phosphokinase (CPK), myocardial depressant factor (MDF), and tissue adenosine triphosphate (ATP) were done in the course of 4-hour treatment periods followed by 2-hour observation periods. Best survival at 4-hour and 6-hour levels were achieved in LV + RA bypass. Cysteine and ribose reduced survival when added to the pump supported (LV + RA bypass) group. Cysteine/ribose improved survival over the no treatment group. O2 consumption increased significantly in the groups with best survival but remained unchanged from control or shock levels when cysteine/ribose were added. Unusually high levels of CPK, acid and alkaline phosphatase, and MDF occurred in both groups receiving cysteine/ribose, indicating significant organ damage correlating with poor survival. Lactate levels were less predictive. Heart tissue ATP levels were higher in groups with good survival. Liver ATP levels were lower in high survival groups. Lung ATP did not differ between groups.

Simple alternatives using a single centrifugal pump for biventricular assistance in cardiogenic shock

The application of pumps and other mechanical and physiologic aids for improving circulation and heart recovery must be based on physiologic requirements. The needs of circulation and cardiac recovery are different and depend on competence of the right ventricle as well as the left ventricle and the pattern of cannulation and decompression. Our studies of various bypass techniques and drugs in a standardized severe cardiogenic shock model lead us to believe that biventricular decompression can be accomplished with a single centrifugal pump without an oxygenator. Cardiogenic shock and severe biventricular failure was best treated by LV + RA bypass, based on survival, hemodynamics and metabolism. LA + RA bypass was the next best. LA bypass, LV bypass, substrates (cysteine and ribose) and nitroprusside were intermediate. Circulatory support is not enough unless appropriate cardiac decompression ensures myocardial recovery.

White clot syndrome

Heparin therapy is currently a vital component in the medical management of thromboembolic events. Despite its widespread use, it is associated with relatively few complications, and these are usually minor and quickly reversible. Recently a much more dramatic and serious complication of heparin therapy has been identified. In heparin-induced thrombocytopenia with associated thrombosis or "white clot syndrome," patients have paradoxic thromboembolic events while receiving heparin. These events are of acute onset and of major consequence, often resulting in limb loss or death. This paper describes our own experience with ten patients in whom the white clot syndrome occurred during heparin therapy for thrombotic or embolic events. Both porcine and bovine heparin preparations were being given through various routes. In the three cases in which platelet aggregation testing was completed, results were positive. Our ten patients ultimately had a 20% major limb amputation rate and an overall 50% mortality.

Single-pump techniques for assisted circulation in cardiogenic shock: experimental evaluation and case report

Acute cardiogenic shock or bridging to transplantation often involves the need for circulatory and cardiac support systems that are more effective than the intraaortic balloon pump. Biventricular failure, which is present in many cases, is generally treated with total cardiac replacement or with a complex of pumps and oxygenator that makes application difficult. With the goal of developing a universally applicable method of cardiac and circulatory support, we undertook a series of canine experiments designed to evaluate the effect of various treatment methods on survival, hemodynamics, and metabolic function. The series involved 123 dogs, in which cardiogenic shock was induced by means of multiple coronary artery ligations. The individual animals were then subjected to bypass, treated medically, or left untreated, depending on random selection. Each treatment lasted for 4 hours and was followed by a 2-hour period of observation. The following single-pump methods were tested: 1) left ventricular (LV) bypass, 2) left atrial (LA) bypass, 3) left ventricular and right atrial (LV + RA) bypass, 4) left atrial and right atrial (LA + RA) bypass, 5) LV + RA bypass, plus treatment with substrates (cysteine and ribose), and 6) LV + RA bypass, plus treatment with fluosol. Each bypass system incorporated a single reservoir and a centrifugal pump, and blood was returned to a femoral artery. Medical therapy consisted of either 1) treatment with sodium nitroprusside alone or 2) treatment with substrates alone. With respect to survival and hemodynamic effects (as reflected by oxygen consumption), LV + RA bypass and LA + RA bypass proved superior. During the posttreatment period, LV + RA bypass was associated with the highest survival rates and, therefore, with the most satisfactory recovery of myocardial or cardiac function. Despite the limited desaturation produced during venous shunting from the right atrium, perfusion of the entire body and consumption of oxygen were least in the LV + RA bypass group. The addition of substrates, or even of fluosol, caused a reduction in oxygen consumption. Our experience also includes one clinical case in which LA + RA bypass was used to support a 57-year-old man for 32 hours, after left atrial bypass alone proved inadequate. The dual-chamber technique brought about an improvement not only in hemodynamics but also in blood-gas values and pH. On the basis of this case and the canine experiments, we conclude that LV + RA and LA + RA bypass techniques offer safe, effective means of long-term temporary support for patients in severe cardiogenic shock.

Effects of postoperative carbohydrate overfeeding

Forty-three indirect calorimetric studies were performed on 24 patients who received postoperative supplemental nutrition for a total of 1088 days. Patients were retrospectively grouped into Group 1 (G1) (respiratory quotient greater than 0.95) and Group 2 (G2) (respiratory quotient less than 0.95). The two groups had similar preoperative biochemical values, prognostic nutritional index, nitrogen intake and excretion, predicted resting energy expenditure and caloric intake. Minimal postoperative biochemical changes were noted between the two groups. Postoperative length of stay was longer for GI than GII patients (P = NS). However, septic episodes and mortality were higher (100% vs 40% and 28% vs 10%, P greater than 0.05), respectively, in G1 than in G2 patients. It is concluded that carbohydrate overfeeding may be associated with a high morbidity and mortality.

Management of intra-abdominal lymphomas

Fifty-nine patients (mean age 65) were evaluated for intra-abdominal lymphomas, localized or disseminated, during the period between 1977 and 1985. These lymphomas were lymphocytic (66%), histiocytic (17%), follicular (10%), and mixed (7%). Liver and retroperitoneal nodes were most frequently involved (32%), followed by stomach (31%), bowel (17%), and spleen (20%). Thirty-five patients (59%) underwent some type of surgical procedure supplemented by either chemo- or radiation therapy. Curative and palliative resections accounted for 40 per cent and 26 per cent, respectively while diagnostic laparotomy with or without staging accounted for 34 per cent. The 1-month postoperative mortality was 20 per cent. The 5-year survival was 12 per cent for the surgical group and 0 per cent for the medical group (P less than 0.05). Patients with lymphomas of the stomach and spleen, treated surgically, fared better than their medical counterparts. Most patients in this series died of their disease (55%) or from attempts to eradicate it.

Comparison of arteriography and noninvasive techniques for the diagnosis of carotid artery disease. A statistical analysis of 140 patients

The carotid arteriograms of 140 patients are compared to noninvasive studies performed on the same group using a SAS statistical package for correlation and identity of information obtained. Chi-square and gamma is calculated for all pairs using total number of arteries and also individual sides of the neck. These reveal significant relationship and identity of information for the arteriograms and the Echoflow (continuous wave Doppler imaging) (Diagnostic Electronic Corp.; Lexington, MA). Discrepancies found between the two groups are a higher frequency of normal findings in the arteriograms and a higher frequency of significant stenoses in the Echoflow group. Differences in frequency of occlusion as a diagnosis are difficult to explain because of the time interval between exams. Other noninvasive studies--OPG, wave-form analysis, supraorbital directional flow--showed poor or no correlation and were unreliable for surgical decisions. A comparison of x-ray interpretations (original report, review interpretation, calculated lumen) reveals statistical identity, although there was a 10 per cent variation in those classified as normal and significant stenosis. No attempt was made to determine whether arteriography or Echoflow was more accurate.

Concepts in assisted circulation

Assisted circulation by extracorporeal and extracardiac bypass techniques must be based on the requirements of the heart and of the total body, though these may differ. The cardiac problem in cardiogenic shock is more likely to be a biventricular problem demanding decompression of both sides. Extra pulmonary oxygenation should be avoided because of complexity in long-term use. Principles of assisted circulation may be applied in an extra-thoracic temporary manner or as an intracorporeal long-term device without removal of the heart. We have compared a number of extracorporeal mechanical bypass techniques (left ventricular bypass, left atrial bypass, right atrial plus left ventrical bypass, and right atrial plus left atrial bypass) in dogs at different flow rates with control groups (nitroprusside, metabolic substrates, and no therapy) for survival during and after 4-hour treatment periods in a standard severe myocardial infarction preparation with biventricular failure. The left ventricle was cannulated in a retrograde manner. Right atrial bypass was mixed with oxygenated left ventricular blood before return without oxygenation. Results in 50 dogs revealed that without treatment 20% survived; left ventricular plus right atrial bypass provided 100% survival during the 4-hour treatment, whereas left ventricular bypass and nitroprusside were intermediate with approximately 70% survival. Respiration and acid-base balance were not significantly altered by right atrial bypass, which provided adequate decompression of the right ventricle. Flow rates of 50% of control levels were adequate to provide normal or increased peripheral circulation as well as decompression of both ventricles and maintenance of sinus or nodal rhythm. Left atrial or left ventricular bypass alone was unable to support the heart or circulation in severe failure. Hemodynamics, including total body perfusion, atrial pressures, and dP/dt were improved significantly only by left ventricular plus right atrial bypass, even though reduced rates of flow were used. Similar findings were seen in lactic acid, CPK, and oxygen consumption. The addition of metabolic substrates currently does not improve survival though they appear to act as metabolic modulators. We conclude that the principle of a low flow left ventricular plus right atrial bypass without an oxygenator offers a technique for long- or short-term assistance.

Activated clotting time for control of anticoagulation during surgery

Two groups of patients undergoing extracorporeal bypass were compared for heparin activity and for heparin and protamine dosage. In group I (18 patients), a uniform dosage pattern was neutralized at the end to a normal clotting time. In group II (43 patients), heparin and terminal protamine doses were regulated by activated clotting times (ACT) using a Hemochron (International Technidyne Corp., Metuchen, NJ). In group II there was a 39 per cent reduction of total heparin dose per case, protamine was reduced 76 per cent, and if the initial heparin doses were excluded, maintenance heparin was reduced 73 per cent. No pattern of heparin administration could be applied to all patients. Heparin half-life varied from 43 to 220 minutes. Other factors that alter heparin activity during bypass revealed no statistical differences. Plasma Hgb was significantly higher in group I, and platelet counts the day following operation were higher in group II. ACT allows tailoring heparin and protamine without the unnecessary dangers of variations in patient response and drug potency.

Prognostic Nutritional Index: its usefulness as a predictor of clinical course

Despite mounting evidence, a question still exists as to the true clinical relevance of varying degrees of malnutrition, the role of currently measured nutritional parameters in identifying malnutrition and predicting clinical risk in individual patients, and the efficacy of nutritional therapy. This study was designed to document the usefulness of the Prognostic Nutritional Index (PNI) as a predictor of clinical course. The nutritional assessments and clinical records of 328 subjects in a Veterans Administration Hospital were reviewed, PNI and complication rates were determined for each of the subjects, and the data statistically analyzed. The PNI was found to be a useful indicator of malnutrition and predictor of clinical course. The PNI appeared to be a more sensitive index of clinical outcome than did comparison of individual nutritional parameters to accepted norms, although it accounted for only 17% of the information needed to predict clinical course perfectly.

Complications of heparin-induced thrombocytopenia

Four cases are presented which are believed to represent thrombocytopenia associated with intravascular thrombosis and vascular occlusion in patients receiving heparin. Patients with gangrene all had pre-existing arterial disease and arterial insufficiency. Such venous and arterial thromboses are paradoxic and unpredictable and are completely against the goal of therapy. These complications may have been prevented if the developing thrombocytopenia was discovered earlier and heparin discontinued. Three of these patients died as a result of their complications, and one had an amputation. The unpredictable pattern of such paradoxic reactions requires close monitoring of the platelet count as well as activated PTT and prothrombin time.

Massive impalement wound of the chest. A case report

A 29-year-old man sustained an impalement wound of the right side of the chest with a 6 foot long, 4 by 4 inch wooden post during a high-speed automobile accident. The post entered the right side of the chest anteriorly and exited posteriorly. The great vessels of the chest were spared, but the right lung was lacerated and contused. Removal of the post, treatment of pulmonary parenchymal damage, and reconstruction of the two large chest wall defects presented problems in management. Rapid transport of the patient to the hospital, effective emergency treatment, surgical repair of the chest injury, and appropriate supportive measures contributed to his survival.

Results and complications of intraaortic balloon pumping in surgical and medical patients

The intraaortic balloon was attempted for therapy in 94 patients and successfully placed in 86. The balloon catheter could not be passed through the femoral or iliac artery in 12 patients (13 percent) of the group; in 4 of these the balloon was inserted through an aortic arch graft. The medical indications were cardiogenic shock and preinfarction angina. Ten of the 14 patients in the group with shock survived when treated with an aortic balloon without emergency surgery. Indications for balloon pumping in the surgical group included inability to wean the patient from the pump-oxygenator, postoperative shock and prophylactic placement of the balloon for poor ventricular function. Inability to remove a patient from pump-oxygenator support was the most common surgical indication, and 47 percent of patients were long-term survivors. Only 1 of the 17 patients for whom balloon pumping was used prophylactically died. Complications occurred in 17 percent of the entire group of 86 patients although the rate for medical patients with cardiogenic shock was 50 percent. The most common complication was arterial insufficiency requiring removal of the balloon. Four patients had permanent damage to the legs from ischemia, one patient requiring bilateral amputation. The overall incidence of serious arterial obstruction was 10 percent. Other complications included balloon displacement with arterial obstruction and pericardial tamponade from anticoagulant agents resulting in death.

Increased oxygen pressure to improve the efficiency of membrane oxygenators

Increased O2 pressure was used in a specially constructed oxygenator to test the concept of improved oxygen transfer with hyperbaria. Three membranes were tested: 5-mil Silastic, 1-mil copolymer, and 0.5-mil Teflon. Results are analyzed in terms of pressure, venous saturation, and flow. The 5-mil Silastic proved to be the most reliable and efficient at all levels of saturation and pressure. Oxygen transfers up to 100 cc/m2/min were recorded at lower venous saturations. Normal pCO2 differentials were maintained at atmospheric pressure but decreased as pressure increased. For the Silastic and copolymer membranes, peak efficiency for O2 transfer was at oxygen pressure 3 lb/in2, or 140 mmHg. This usually required a blood pressure of over 300 mmHg using an average blood layer of 0.5 mm. Changes of pressure were more critical than flow, although O2 transfer was found to increase up to flows of 1200 cc/min/m2. Pressure levels of 0-30 lb/in2 were tested. Teflon was most efficient at pressures of 10-15 lb/in2, and did not transfer CO2 in detectable amounts at these pressure levels. Plasma hemoglobin, WBC, and platelets were not seriously altered when studied over 4-hour periods at constant pressures.

The role of intraaortic balloon counterpulsation in patients undergoing cardiac operations

Intraaortic balloon counterpulsation (IABC) was used to assist 60 patients undergoing cardiac operations for reasons of acute left ventricular failure (18 patients) or electively for indications in high-risk coronary and valvular heart disease (42 patients). Nine of 18 patients achieved hemodynamic stability when treated for acute perioperative or postoperative cardiogenic shock. Four of these died from problems unassociated with postoperative left ventricular failure and 5 were long-term survivors, indicating a potential salvage of 50%. In 42 high-risk patients, IABC was used electively to control preinfarction angina before operation (21 patients) and prophylactically to prevent postoperative low-output failure in another 21 patients with severe coronary and valvular heart disease. Thirty-nine, or 93%, of these patients survived. There were no deaths in the preinfarction angina group, 1 death in the group with coronary disease and ejection fractions less than 30%, and 2 deaths in those with valvular heart disease and congestive failure. Seven patients developed thrombotic or ischemic complications, but no permanent damage resulted. IABC is an important form of assistance for any patient with preoperative, intraoperative, or postoperative left ventricular failure and adds safety and hemodynamic stability for the high-risk patient with preinfarction angina or poor ventricular function.

Comparative hemodynamic consequences of inflation hold, PEEP, and interrupted PEEP: an experimental study in normal dogs

Cardiac output and airway, intrathoracic, arterial, pulmonary artery, left atrial, and central venous pressures were studied in 8 mongrel dogs. They were anesthetized and ventilated with (1) inflation hold of various duration, (2) continuous positive end-expiratory pressure and one breath off). The results indicate a minimal decrease in cardiac output (of approximately 5 per cent) with inflation hold. Diminished cardiac output was noted with increasing levels of continuous PEEP. The severity of the decrease in cardiac output wasproportional to the airway pressure. The higher levels (20 cm H2O) OF PEEP were associated with profound decreases. Utilization of a technique of interrupted PEEP substantially reduced the adverse hemodynamic effects in the dog.

The use of saline-washed frozen red cells for extracorporeal bypass

The use of saline-washed frozen red cells and homologous whole blood during cardiopulmonary bypass was compared in two groups of patients with similar medical disease, sex, age, pump time, types of operation, and surgical techniques. A technique for using saline-washed frozen red cells for cardiopulmonary bypass with no increase in hemolysis is described. Increased platelet counts were present at the end of bypass in the patients who were given frozen cells. The availability and the many advantages of frozen cells, such as improved oxygen transport and the absence of homologous blood reactions and viral infections, make them the preferred cellular blood component for use during open-heart operations.