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Biomedical subjects

E Lowenstein

Publications and source records attributed to E Lowenstein.

At least 91 records · Page 5Linked to original sources
PubMed1982

Hypothermic ischemic arrest versus hypothermic potassium cardioplegia in human beings.

To determine if the addition of potassium enhances the myocardial protective effect of intracoronary perfusion hypothermia during aortic cross-clamping, 50 patients undergoing aortocoronary bypass grafting were studied in a randomized, prospective, double-blind fashion. Twenty-six patients received a cold crystalloid solution infused with a handheld syringe into the root of the cross-clamped aorta every 20 minutes, and 24 patients received the same solution but with 25 mEq/L of potassium chloride added, infused in a similar manner. Both groups were analyzed by mortality, rate of perioperative myocardial infarction (electrocardiographic changes, MB-CPK enzyme release, and preoperative and postoperative gated cardiac blood pool scans), intraoperative hemodynamic changes, intraoperative lactate determinations, postoperative arrhythmias, and requirement for pressor or intraaortic balloon pump support. One patient in the potassium cardioplegia group died (massive pulmonary embolism), and none in the hypothermic perfusion group died. Possible perioperative myocardial infarction was diagnosed by more than one marker in 4 of 26 patients in the hypothermic perfusion group and 5 of 24 patients in the potassium group (p = 0.61). There were no differences between the two groups in terms of hemodynamic changes, lactate production, postoperative arrhythmias, or the need for postoperative hemodynamic support. This study in human beings could not demonstrate a specific protective effect of potassium, beyond that afforded by myocardial perfusion hypothermia and wash-out. The data suggest that myocardial hypothermia, achieved through cold intracoronary arterial perfusion, may be the most important beneficial component of so-called cardioplegia for attaining effective intraoperative myocardial preservation in human beings.

Arrhythmias, Cardiac↗
PubMed1982

Acute oliguria after cardiopulmonary bypass: renal functional improvement with low-dose dopamine infusion.

Hemodynamic and renal function response to low-dose (100 and 200 micrograms/min) dopamine infusion was studied in 15 adult cardiac surgical patients who manifested combined oliguria and left ventricular dysfunction postoperatively. Patients were studied an average of 6.6 h after ICU admission, at normothermia and after 2 consecutive hourly urine output determinations of less than 0.5 ml/kg . h in the presence of a left atrial or pulmonary artery occlusion pressure over 12 mm Hg. Dopamine infusion at 100 micrograms/min produced improvement in creatinine, osmolar and free water clearances (70 +/- 10 to 115 +/- 13, 37 +/- 4 to 93 +/- 16 and --15 +/- 2 to --37 +/- 10 ml/min, respectively), and urinary sodium concentration (15 +/- 5 to 29 +/- 10 mEq/L). Urine flow improved overall from 22 +/- 2 to 54 +/- 9 ml/h; however, in 9 of 15 patients, flow was less than 0.5 ml/kg . h (33 +/- 5 to 50 +/- 6 ml/h). In each of these 9 patients, dopamine infusion at 20 micrograms/min further improved urine flow as well as measured renal function. Plasma renin activity measured in 9 of the 15 patients before and during the 100 micrograms/min dopamine infusion was decreased from 1.95 +/- 0.57 to 0.73 +/- 0.39 ng/ml . h. The hemodynamic effect of both dopamine doses was increased cardiac output coupled with decreased systemic (SVRI) and pulmonary vascular resistance index (PVRI). In these 15 patients, low-dose dopamine infusion produced significant improvement in renal function, with resolution of oliguria in every case, and with no deleterious hemodynamic effect.

Adult↗
PubMed1981

Regional ischemic ventricular dysfunction in myocardium supplied by a narrowed coronary artery with increasing halothane concentration in the dog.

The effects of increasing inspired halothane concentration (0.5, 1.0, 1.5, 2.0 per cent) upon left ventricular myocardium supplied by a critically narrowed coronary artery and a normal coronary artery were studied in 11 open-chested dogs. Regional ventricular function was measured by continuous recording of ventricular segment length using pairs of implanted miniature ultrasonic length detectors in the left anterior descending coronary artery (LAD) and left circumflex coronary artery (LC) territories before and during critical stenosis of the LAD by a micrometer-controlled snare. Critical narrowing was documented by ischemic regional ventricular function (i.e., post-systolic shortening; systolic lengthening) limited to the LAD territory when FIO2 = 0 for 90 seconds. Hemodynamic variables (aortic, left atrial and left ventricular pressure, and heart rate) were measured, ECG lead II was recorded, and the first derivative of left ventricular pressure (LV dP/dt) and coronary perfusion pressure derived for each halothane concentration before and during LAD narrowing. Increasing halothane was associated with equivalent progressive depression of global ventricular function before and during LAD constriction. Prior to LAD constriction, no ischemic changes in regional function occurred. Regional ventricular function was normal during 0.5 percent halothane in the presence of LAD constriction. With increasing halothane during LAD constriction, ischemic regional ventricular function was observed in the LAD territory in eight of eleven hearts, whereas regional ventricular function remained normal in the LC territory. The epicardial ECG was recorded in three dogs and was insensitive as an indicator of ischemia, becoming abnormal only after severe ischemic changes were established. In these studies, in which heart rate remained constant, arterial blood pressure and LV dP/dt decreased, and left ventricular end-diastolic pressure increased, decrease in blood flow and oxygen delivery due to a lower perfusion pressure distal to the coronary artery narrowing appears to be primarily responsible for the observations. The authors hypothesize that clinically unapparent episodes of regional myocardial ischemia distal to narrowed coronary arteries may be an important cause of perioperative myocardial infarction.

Animals↗
PubMed1981

Quarrels, separations and infidelity in the two days preceding self-poisoning episodes.

Self-poisoning patients and their relatives or friends were interviewed following admission to a general hospital. Events involving a key person, especially quarrels, were common in the two days preceding the overdose. Quarrels were more common events in women than men. It is argued that the frequency of quarrels supports the idea that hostility is important in the motivation of self-poisoners. It is hypothesized that differences in the frequency of key events and those under and over 36 years might arise from depressive illness being more frequently found in the older group.

Adult↗
PubMed1981

Myocardial temperature mapping. Improved intraoperative myocardial preservation.

An improved approach to intraoperative myocardial preservation technique to ensure uniform myocardial cooling past critically stenosed arteries was developed for patients undergoing aorta-coronary bypass grafting. Proximal anastomoses are done and then, after institution of cardiopulmonary bypass, a separate roller pump head is used to administer a specific controlled volume of cardioplegic solution (1 L) through a 4 degrees C coil to provide controlled pressure in the root of the cross-clamped aorta. Midmyocardial wall temperatures in the anterior, posterolateral, inferior, and septal walls of the left ventricle are measured. Distal anastomoses are then performed sequentially, beginning with the warmest region. After each distal anastomosis, 400 ml of cardioplegic solution are again administered into the aortic root. This approach has been used in 100 consecutive patients from July, 1979, through July 1980 (Group I). and these patients were compared to 97 consecutive patients undergoing aorta-coronary bypass grafting in the previous year (July, 1978, through June, 1979) (Group II) who had myocardial preservation with potassium cardioplegia administered by syringe injection and without regional temperature mapping. There were no perioperative myocardial infarctions in Group I: there were five (5.2%) in Group II (p less than 0.05). A significant reduction in cardiac deaths was also achieved, with two (2.0%) such deaths in Group I and eight (8.2%) in Group II (p less than 0.05). The data suggest that delivery of adequate volumes of cardioplegia solutions by a pressure-regulated system, in combination with myocardial temperature mapping to determine the sequence of bypass grafting, can improve myocardial preservation.

Body Temperature↗
PubMed1979

Ventricular pump performance during hypocalcemia: clinical and experimental studies.

We have compared indices of ventricular function during rapid transfusion of citrated (1.5 ml/kg/min) or heparinized (1.5 ml/kg/min) autologous blood in six patients following discontinuation of cardiopulmonary bypass. Infusion of citrated blood was associated with a lowering of plasma ionized calcium concentration ([Ca++], from 0.90 +/- 0.04 to 0.71 +/- 0.4 mM, p less than 0.001) and an increase in pulmonary artery balloon-occluded pressure (PA0, from 9.4 +/- 2.6 to 15.5 +/- 1.7 mm Hg, p less than 0.u1), without a change in left ventricular stroke work index, stroke index, or cardiac index. Transfusion of heparinized blood caused no change in plasma [Ca++]. A rise in PA0, which was similar in magnitude to that observed during citrated blood transfusion, was associated with increased left ventricular stroke work index, stroke index, cardiac index, and mean arterial pressure. Although data obtained during citrated blood transfusion suggest the presence of transient left ventricular dysfunction, its magnitude is not readily expressed in terms of ventricular function curves when accompanied by a simultaneous change in [Cized closed-chest dog by volume loading during hypocalcemia, when mean arterial pressure, heart rate, and [Ca++] were in a steady state, both prior to and following beta blockade with propranolol. Function curves obtained during severe hypocalcemia ([Ca++] = 0.43 +/- 0.02 mM) were shifted significantly to the right and downward, when compared to those obtained during normocalcemia ([Ca++] = 1.06 +/- 0.03 mM). Hypocalcemia combined with beta blockade resulted in severe left ventricular failure, as demonstrated by a flat ventricular function curve.

Aged↗
PubMed1978

Kinetics of intravenous and intramuscular morphine.

The disposition of parenteral morphine was assessed in two pharmacokinetic studies. In Study 1, 10 mg of morphine sulfate was administered by intravenous (IV) infusion, intramuscular (IM) injection, or both, to 8 healthy young adult male volunteers. Plasma morphine concentrations were determined by radioimmunoassay in multiple blood samples drawn after each dose. Mean (+/-SE) kinetic parameters following IV morphine were: volume of distribution (Vd), 3.2 (+/- 0.3) L/kg; elimination half-life (t1/2beta), 2.9 (+/- 0.5) hr; clearance, 14.7 (+/- 0.9) ml/min/kg; extraction ratio, 0.70 (+/- 0.04). After IM morphine, peak plasma levels ranged from 51 to 62 ng/ml and were reached within 20 min of injection. The absorption half-life averaged 7.7 (+/- 1.6) min. Systemic availability was 100% complete. In study 2, 4 elderly male patients (61 to 80 yr of age) received 45 to 80 mg of morphine sulfate IV prior to operative repair of an abdominal aortic aneurysm. Morphine pharmacokinetics were determined as described above. Kinetic variables were Vd, 4.7 (+/- 0.2) L/kg; t1/2beta, 4.5 (+/- 0.3) hr; clearance, 12.4 (+/- 1.2) ml/min/kg; extraction ratio, 0.59 (+/- 0.05). Both studies demonstrate that morphine distribution is rapid and extensive and its t1/2beta relatively short. IM morphine is rapidly and completely absorbed.

Adult↗
PubMed1978

The effect of hemodilution with albumin or Ringer's lactate on water balance and blood use in open-heart surgery.

To determine the effect of intraoperative albumin administration on blood use, water balance, and postoperative clinical course, we studied two groups of adult cardiac surgical patients. Group I (30 patients) received 25 gm of albumin during withdrawal of 2 units of blood prior to cardiopulmonary bypass (CPB) and 50 gm of albumin in the oxygenator prime. Group II (32 patients) received no albumin prior to the end of CPB. No difference in clinical course could be identified, nor was there a significant difference in blood use. Group I patients had lower hematocrit values intraoperatively from the time of blood withdrawal until the conclusion of operation. Coronary artery bypass operations were associated with greater positive water balance than were heat valve operations. Forty-three percent of the patients having coronary artery bypass grafting had a positive water balance greater than 5 liters, whereas 50% of those undergoing valve procedures had a balance less than 3 liters. We conclude that the principal effect of withholding albumin under these circumstances is to increase net positive water balance. The greater positive water balance does not appear to be detrimental.

Adult↗