PubMed Health⌕ Search

Biomedical subjects

E A Hessel

Publications and source records attributed to E A Hessel.

At least 19 recordsLinked to original sources
PubMed1989

Intraoperative management of abdominal aortic aneurysms. The anesthesiologist's viewpoint.

Factors that influence the choice of anesthetic, monitoring methods, and fluid management for aneurysm repair are reviewed, with particular attention to epidural anesthesia and analgesia and the pulmonary artery catheter. Management of bleeding, renal preservation, temperature control, and myocardial ischemia are discussed, and special anesthetic issues associated with ruptured aneurysms and juxtarenal and suprarenal surgery are summarized.

Anesthesia, Conduction↗
PubMed1986

Cardiovascular response to rapid infusion of lactated Ringer's.

Cardiovascular response to rapid infusion of lactated Ringer's was investigated in 5 adult dogs (average body weight = 21.1 kg) under 1% halothane anesthesia. Following implantation of aortic flow probe and left atrial line, the chest was closed and splenectomy was performed prior to the experiment. Warmed lactated Ringer's was administered at five different infusion rates (2.5, 5, 10, 15 and 20 ml/kg/min in random sequence) to each dog until left atrial pressure (LAP) reached 20 mmHg or a maximum of 50 ml/kg had been infused. Subsequent infusions were done after stroke volume (SV) spontaneously returned to the control level. Cardiac output (CO), SV, heart rate (HR), mean arterial pressure (MAP), LAP and central venous pressure (CVP) were monitored simultaneously during infusions. HR was stable during infusions, whereas MAP increased by 39% of control. Response of LAP to volume infused was nearly linear at fast infusion rates (10, 15 and 20 ml/kg/min). Response of LAP to slow infusion rates (2.5 and 5 ml/kg/min) was curvilinear (decelerating curve). The relationship between CVP and volume infused was similar to LAP vs. volume infused. Ventricular function curves (SV, CO and stroke work vs. LAP) were also influenced by the rate of infusion with steeper curves at slow infusion rates than curves derived from fast infusion rates. However, initial changes in SV and CO curves were not significantly affected by the rate of infusion. We conclude that the cardiovascular response to rapid infusion of lactated Ringer's is rate dependent but initial changes in SV and CO curves are not significantly affected at infusion rates of 2.5, 5, 10, 15 or 20 ml/kg/min.

Animals↗
PubMed1984

The early course of pulmonary artery hypertension in patients undergoing mitral valve replacement with cardioplegic arrest.

In an effort to describe the immediate course of pulmonary hypertension following mitral valve replacement, we reviewed preoperative and postoperative data from 62 patients who underwent mitral valve replacement. Patients were divided based on the absence (Group I) or presence (Group II) of severe preoperative pulmonary hypertension, defined as a mean pulmonary artery pressure greater than or equal to 40 mm Hg. Group II patients were subdivided based on the absence (Group IIa) or presence ( Group IIb) of markedly elevated preoperative pulmonary vascular resistance indices, defined as a greater than or equal to 700 dynes . sec . cm-5 . m2. Pulmonary artery wedge pressures fell promptly following mitral valve replacement in all groups, but the course of other hemodynamic parameters varied among groups. Cardiac index increased significantly among Group I and IIb patients but not among Group IIa patients. Group I patients did not have significant changes in mean pulmonary artery pressure and pulmonary vascular resistance index. Group IIa patients had substantial reductions in mean pulmonary artery pressure while pulmonary vascular resistance index remained near 400 dynes . sec . cm-5 . m2. Group IIb patients had substantial reductions in mean pulmonary artery pressure while pulmonary vascular resistance index fell significantly to about 400 dynes . sec . cm-5 . m2. Primary valvular lesion and pharmacologic support were insignificant variables. Data from these hemodynamic groups suggest that at least three mechanisms contribute to the pulmonary hypertension seen in mitral valve disease: passive transmission of elevated left atrial pressures, reactive pulmonary arteriolar vasoconstriction, and morphologic changes in the pulmonary vasculature. The first two mechanisms appear to be rapidly reversed following mitral valve replacement. While others have described the regression of pulmonary hypertension several months following mitral valve operations, data presented here suggest that changes in pulmonary artery pressures and pulmonary vascular resistance index may occur much earlier.

Adult↗
PubMed1983

Noninvasive Doppler determination of cardiac output in man. Clinical validation.

A noninvasive technique for assessing cardiac output (CO) was evaluated by comparing it with thermodilution determinations in patients in the intensive care unit. The new method uses pulsed ultrasound to measure aortic diameter and continuous-wave Doppler ultrasound to obtain aortic blood velocity. An initial study evaluating just the velocity measurement showed that changes of the Doppler index of output (DI) correlated well with those of thermodilution cardiac output (TDCO). Linear regression analysis yielded delta DI = 0.87 delta TDCO + 0.14 (r = 0.83, n = 95). Using a university research instrument these measurements were possible in 54 of 60 patients (90%). A second study using a prototype commercial device incorporated the diameter measurement. Ultrasonic cardiac output (UCO), calculated as the time integral of velocity multiplied by the aortic area, was compared to TDCO. The data, obtained from 45 of 53 patients (85%), are described by the linear regression UCO = 0.95TDCO + 0.38 (r = 0.94, n = 110) over a range of 2-11 l/min. Patients with aortic stenosis, aortic insufficiency or a prosthetic valve have been excluded from the second study due to conditions likely to violate the assumptions upon which the calculation of absolute cardiac output is based. These results indicate that accurate CO can be measured by noninvasive ultrasound in most patients. The technique may be useful for extended CO monitoring in acute care patients and for CO assessment in many other types of patients undergoing diagnostic studies and therapeutic interventions.

Aorta↗
PubMed1983

Influence of propranolol on supraventricular tachycardia early after coronary artery revascularization. A randomized trial.

A total of 116 patients undergoing coronary revascularization were randomized preoperatively in a double-blind manner to receive 80 mg daily of propranolol or placebo in the postoperative period. Preoperatively, all patients had been receiving at least 80 mg of propranolol a day to the time of the operation. In addition, all patients had a left ventricular ejection fraction of 0.4 or more, no history of supraventricular tachyarrhythmia (SVT), and no need of digitalis preparations or other antiarrhythmic drugs. All patients were monitored for 5 days and propranolol or placebo was started 24 hours postoperatively. SVT was documented with biatrial electrograms in all cases. Study groups were similar in postoperative creatine kinase MB levels and postoperative weight gain, but the placebo group tended to be older and have more grafts per patient. Seven patients randomized were dropped from the study, two with perioperative infarction, four with persistent ventricular arrhythmias necessitating quinidine or procainamide, and one with persistent postoperative hypotension (placebo). There were no significant differences in the incidence of postoperative SVT in these two groups: 13.2% in the propranolol group and 16.1% in the placebo group. We conclude that 80 mg daily of propranolol given postoperatively to patients undergoing coronary revascularization does not effectively reduce the incidence of SVT.

Clinical Trials as Topic↗
PubMed1982

Circulatory dynamics during surface-induced hypothermia under halothane-ether azeotrope anesthesia.

Circulatory dynamics during surface- induced deep hypothermia using the halothane-diethyl ether azeotrope in 100% oxygen (O2) without circulatory arrest and 95% O2 and 5% carbon dioxide (CO2) with and without 60 minutes of arrest were evaluated in 15 adult mongrel dogs. Mean arterial pressure was lower in animals given 5% CO2 than in animals given 100% O2 during cooling. Cardiac output in the 5% CO2 groups increased until 30 degrees C cooling and then gradually decreased to 29% of control at 20 degrees C. Cardiac output in the 100% O2 group progressively decreased to 16% of control at 20 degrees C cooling and was 51 to 77% of the output in the 5% CO2 animals at comparable temperatures throughout the hypothermia procedure. The differences in cardiac output were attributed primarily to changes in stroke volume since heart rates were not significantly different. These changes were probably secondary to differences in systemic vascular resistance, which had increased sixfold in the animals given 100% O2 and had only doubled in the 5% CO2 groups at 20 degrees C during cooling. Hemodynamic variables in animals given 5% CO2 did not reveal significant differences in arrested versus nonarrested animals during early rewarming. However, with further warming, cardiac output, stroke volume, left ventricular stroke work, and mean pulmonary arterial and pulmonary artery wedge pressures were lower, and systemic and pulmonary vascular resistances were higher in the arrest group. We conclude that the improved results with halothane-diethyl ether azeotrope in 95% O2 and 5% CO2 during surface hypothermia are due to a greater cardiac output and reduced peripheral vascular resistance.

Anesthesia, Inhalation↗
PubMed1982

Termination of ventricular tachycardia by programmed extrastimuli from an externally-activated permanent pacemaker.

Two patients with hemodynamically well-tolerated recurrent ventricular tachycardia, drug resistant and previously requiring numerous external electrical cardioversions, had a permanent pacemaker implanted which could be programmed to deliver extrastimuli to convert the ventricular tachycardia to normal sinus rhythm. The patient- or physician-activated device can be programmed to induce or terminate ventricular tachycardia with extrastimuli delivered at the predetermined intervals which consistently induced or terminated the arrhythmia in the electrophysiology laboratory, allowing repeated evaluation of drug regimens. The pacemaker has reliably, painlessly, and consistently induced and terminated repeated episodes of ventricular tachycardia. This programmable pacemaker offers an alternative therapy for patients with hemodynamically well-tolerated refractory ventricular tachycardia.

Aged↗
PubMed1982

Results of a survey of the professional activities of 811 cardiopulmonary perfusionists.

We queried 811 cardiopulmonary perfusionists in North America on the equipment and techniques they currently use for cardiopulmonary bypass, their professional training, and their income structure. Most cardiac surgical teams use one of four types of bubble oxygenators; only 5% use a membrane oxygenator exclusively. More than 80% monitor the activated clotting time during cardiopulmonary bypass, and 61% confirm the adequacy of heparinization with this test before initiating bypass. Most perfusionists surveyed, 507, are hospital salaried; 117 are employed by cardiac surgeons; and 72 have established a fee for service arrangement. In 1980, reported incomes for cardiopulmonary perfusionists ranged between $12,000 and $110,000, with a mean of $25,000. Only 196 respondents (24%) were graduates of accredited training programs in perfusion technology, but 618 (76%) were board certified in cardiovascular perfusion. This study presents an in-depth survey of the present status of perfusion technology, a discipline which has grown up around the practice of cardiac surgery.

Cardiopulmonary Bypass↗
PubMed1981

The practice of coronary artery bypass surgery in 1980.

We obtained information from 677 cardiac surgeons in the United States on the type of practice, case load, and techniques currently used for coronary bypass operations. These surgeons collectively performed 93,000 bypass operations in 1979. Less than 25% of these procedures were done in university or federal hospitals; the majority were performed in the private sector by surgeons engaged in a single specialty group practice. The mean case load in 1979 was 137 operations per surgeon, and only 46 (6.8%) did fewer than 25 bypass operations during that year. These surgeons devote a relatively small percentage of their professional activity to other areas in thoracic surgery--the majority do not perform congenital heart surgery and two thirds devote less than 10% of their professional activity to general thoracic surgery. Compared with our previous national survey done in 1975, techniques used for bypass grafting have changed considerably over the past 5 years. An increasing number of surgeons conduct cardiopulmonary bypass with an arterial input line introduced into the ascending aorta and with a single cannula for venous drainage and do not routinely vent the left ventricle. Cold chemical cardioplegia has become the technique of choice (by 91% of surgeons) for myocardial protection, sequential bypass grafts are now widely employed, and 83.2% of surgeons perform all distal anastomoses during a single period of cardioplegic arrest.

Cardiac Surgical Procedures↗
PubMed1981

Prevention of acquired transient defect in platelet plug formation by infused prostacyclin.

Cardiopulmonary bypass in baboons produced transient severe platelet dysfunction (bleeding times prolonged to 27.8 +/- 1.4 min compared with 3.9 +/- 0.7 baseline) that was associated with a parallel release of platelet alpha-granule proteins into plasma (platelet factor 4 and beta-thromboglobulin levels of 28.8 +/- 9.3 and 20.0 +/- 1.8 ng/ml, respectively) and their clearance into urine with a reciprocal depletion from circulating platelets. In contrast, platelet-dense granules did not undergo significant release. The bleeding times normalized rapidly following bypass (8.5 +/- 1.4 min at 1 hr). The infusion of prostacyclin (PGI2) into the bubble oxygenator during bypass (40--80 ng/kg/min) prevented the prolongation in bleeding time (p less than 0.01 compared with untreated control values) but did not block the release of alpha-granule proteins. Dosages outside this range were associated with prolonged bleeding times. These results show that transient platelet dysfunction occurring during cardiopulmonary bypass represents activation of platelets independent of alpha or dense granule release and is blocked by potent short-acting inhibition of platelet function using PGI2 infused into the oxygenator apparatus at optimal therapeutic doses.

Animals↗
PubMed1980

Determination of cardiac output by thermodilution during hypothermia.

The thermodilution method for estimating cardiac output was compared with the electromagnetic flowmeter technique in 10 mongrel dogs at normothermia and during surface-induced deep hypothermia. Thermodilution curves obtained during cooling or rewarming must be corrected for the baseline drift caused by changing core temperature. At normothermia, the correlation coefficient between the two methods was 0.96 and the reproducibility of the thermodilution technique was 5 percent. Comparable correlation was present during hypothermia. Curves corrected for baseline drift resulted in significantly different output values from those derived from uncorrected curves (p < 0.05). The thermodilution method is valid at low body temperatures. Clinical confirmation of these results, particularly during open heart surgery in infants, is warranted.

Animals↗