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Biomedical subjects

P R Lichtenthal

Publications and source records attributed to P R Lichtenthal.

At least 19 recordsLinked to original sources
PubMed1996

Testing the safety of Baxter continuous cardiac output monitoring system.

The safety of a new continuous cardiac output monitoring system, recently introduced by Baxter Healthcare Corporation's Edwards Critical-Care Division, was evaluated in normal sheep. The study compared the biocompatibility and safety of the Vigilance CCO Monitoring System, which employs a continuous cardiac output (CCO) catheter with Baxter Edward's standard Paceport pulmonary artery catheter. The CCO catheter, which monitors hemodynamic pressures and provides continuous measurement of cardiac output based on the thermodilution principle, contains a thermal filament that is powered and controlled by a unique cardiac output monitor. Parameters were measured periodically in conscious animals and complete necropsies were performed after each study. Time Control, Paceport, and four CCO groups were studied. Selected groups were studied for 3 days (acute), 7 days (subacute), and/or 4 weeks after 3 days of continuous use (recovery). Results showed no significant differences between the CCO and Paceport catheters in any of the parameters studied. On gross pathology, observations were similar. The only difference between catheters were microscopic findings of focal subendothelial or subendocardial changes correlated with areas that could have come into contact with the CCO catheter. In acute groups, these changes consisted of a localized myofiber degeneration or necrosis, while in subacute and recovery groups, consisted only of fibrosis. None of the changes were clinically significant. Thus, the CCO catheter, used in conjunction with the Vigilance CCO Monitoring System, appears to pose no additional risk over a standard Paceport catheter in normal sheep after continuous use for up to 7 days.

Animals↗
PubMed1993

A clinical evaluation of a blood conservation device in medical intensive care unit patients.

OBJECTIVES: This study was designed to a) document the efficacy of a device intended to conserve blood in critically ill patients; b) determine the effect of this blood conservation on hemoglobin concentration and the need for blood transfusions; c) determine if the blood conservation device resulted in interference with arterial pressure waveforms; d) determine if use of the blood conservation device resulted in a difference in the number of accidental needle punctures suffered by healthcare workers. DESIGN: Prospective, randomized, controlled trial. A clinical trial using prospective, random allocation of consecutive eligible patients. SETTING: The medical intensive care unit (ICU) of a university hospital located in a large metropolitan area. PATIENTS: A total of 100 patients who were admitted to the medical ICU, required arterial line monitoring for clinical purposes, and were managed by the ICU medical service. Exclusion criteria included active bleeding or chronic renal failure at the time of ICU admission. INTERVENTIONS: Patients in the experimental group had a blood conservation device incorporated into the arterial pressure monitoring system, while patients in the control group received a conventional arterial pressure monitoring system. MEASUREMENTS AND MAIN RESULTS: Data gathered included: age; gender; ICU discharge status; the duration of ICU stay; time in the study; volume of all blood drawn, discarded, or lost due to leakage; hemoglobin concentrations; blood transfusions; and accidental needle injuries. Arterial pressure waveforms were recorded and inspected for dampening or other deformation. Mean hemoglobin concentrations were compared on ICU admission and at 12-hr intervals. Demographic and clinical characteristics of the two groups were not significantly different. The volume of blood drawn and discarded from arterial catheters was significantly lower in the blood conservation group (blood conservation device: 5.7 +/- 7.5 mL; control: 96.4 +/- 88.5 mL; p < .0001), as was the total volume of blood discarded (blood conservation device: 19.4 +/- 47.4 mL; control: 103.5 +/- 99.9 mL; p < .0001). Mean hemoglobin concentration on admission was similar in the two groups (blood conservation device group: 11.8 +/- 2.5 g/dL; control group: 12.6 +/- 2.3 g/dL). In both groups, the mean hemoglobin concentration declined most rapidly in the first 24 hrs of ICU care and, thereafter, declined more slowly. Although the mean hemoglobin concentration was higher in the blood conservation group after 6 days, statistical significance was not reached until 9.5 days of ICU care. The mean change in hemoglobin concentration (overall: 1.2 +/- 2.2 g/dL) during the study represents a statistically significant (p < .0001) decrease of 9.7%. Hemoglobin concentration during the study decreased by 1.4 +/- 2.2 g/dL in the control group and 1.0 +/- 2.3 g/dL in the blood conservation group (p = nonsignificant). Univariate and multiple regression analysis demonstrated discarded blood volume to be a significant and independent predictor of the decline in hemoglobin concentration. Transfusion requirements were similar in both groups. The blood conservation system did not alter or interfere with pressure waveforms. There were no accidental needle injuries noted. CONCLUSIONS: The conservation of blood in critically ill patients must be a high-priority concern of all healthcare workers. Our data indicate that the blood conservation system eliminates a significant factor in the decline in hemoglobin concentration. With devices as described here, there is no reason to continue the practice of wasting the blood of critically ill patients in order to prevent preanalytic error.

Adult↗
PubMed1987

The effect of ketanserin on blood pressure and platelets during cardiopulmonary bypass.

Ketanserin, a serotonin antagonist, was used to control blood pressure during cardiopulmonary bypass in 12 patients having cardiac surgery. The drug was administered as a 10 mg bolus followed by a continuous infusion of either 40, 80, or 120 mg/hr to maintain mean arterial blood pressure below 70 mm Hg. There were 16 hypertensive episodes of which 15 (93.7%) were successfully controlled with ketanserin. Mean arterial pressure decreased significantly from an average of 72 +/- 3 to 52 +/- 9 mm Hg after 1 min. The effect that ketanserin had on platelets was also evaluated. Neither adverse nor salutary effects were seen in the platelet count, though a significant inhibition of serotonin-induced platelet aggregation was observed. Ketanserin proved effective for controlling hypertension during cardiopulmonary bypass but, despite inhibition of serotonin-induced platelet aggregation, it did not prevent thrombocytopenia.

Aged↗
PubMed1985

Dose-related prolongation of the bleeding time by intravenous nitroglycerin.

The effects of intravenous nitroglycerin (NTG) upon the bleeding time, platelet aggregation response, and plasma 6-keto-PGF1 alpha concentration were measured in 17 patients about to undergo coronary bypass grafting. NTG produced a dose-related prolongation of the bleeding time that correlated with the accompanying decrease in systolic blood pressure. Platelet aggregation was not affected and measurements of 6-keto-PGF1 alpha failed to reveal detectable levels (less than 10 pg/ml) either before or after NTG infusion. This suggests that the prolonged bleeding time associated with NTG infusion may be due to vasodilation and increased venous capacitance, rather than altered vascular-platelet interaction.

Adult↗
PubMed1983

Changes in left ventricular performance related to perioperative myocardial infarction in coronary artery bypass graft surgery.

Strict electrocardiographic, enzymatic, scintigraphic, and hemodynamic criteria for perioperative myocardial infarction (MI) were defined and related to serial assessments of left ventricular performance during rest and exercise in patients seen early and late after coronary artery bypass graft operation. Global left ventricular performance was determined by radionuclide ventriculography from which changes in the pattern of serial postoperative ejection fractions (EF) were obtained. Patients were divided into two groups based on the presence or absence of perioperative MI, and were matched in pairs on the basis of preoperative EF and extent as well as location of coronary artery obstructions. The results indicate that neither short- nor long-term depression in resting EF occurred subsequent to perioperative MI. However, an exercise-related increase in EF eight months postoperatively was depressed in patients who had perioperative MI compared with those who did not. Patients with new Q waves and abnormal postoperative elevation in serum levels of the myocardial isoenzyme of creatine kinase (CK-MB) had a greater early decrease in EF compared with patients without evidence of perioperative MI. However, seven days after operation, the EF in both groups returned to preoperative levels. Patients with abnormal technetium 99m-pyrophosphate scintigrams had changes in perioperative EF similar to those in patients without MI. The presence of low cardiac output syndrome immediately after operation was associated with immediate and short-term decreases in EF, which were not seen in any of the other patient subgroups.

Cardiac Output, Low↗
PubMed1983

Respiratory management after cardiac surgery with inhalation anesthesia.

Improvements in cardiac surgery techniques and anesthetic management have given us cause to re-evaluate the necessity for postoperative mechanical ventilation and delayed extubation after open-heart surgery with inhalational anesthesia. One hundred consecutive patients undergoing various types of cardiac surgery were entered into this study; 94 patients met the requirements for spontaneous ventilation in the immediate postoperative time period and mechanical ventilation was not utilized. Of these 94 patients, 40 (45%) met extubation requirements within 90 min and were subsequently extubated. No patient required reintubation. Six (6%) patients failed to meet the requirements for spontaneous ventilation and, therefore, required mechanical ventilatory assistance postoperatively. In the majority of cardiac patients, the anesthetic technique determines postoperative ventilatory needs. Very poor preoperative physical status and unusually long procedures, however, will probably preclude early extubation or spontaneous ventilation and dictate the need for mechanical ventilation regardless of the anesthetic technique.

Adult↗
PubMed1982

Clinical evaluation of the relative effectiveness of multidose crystalloid and cold blood potassium cardioplegia in coronary artery bypass graft surgery: a nonrandomized matched-pair analysis.

Controversy exists concerning the most effective method of myocardial protection during coronary artery bypass graft operations. Accordingly, we performed a matched-pair analysis between 25 patients receiving multidose hypothermic potassium crystalloid cardioplegia and 25 other patients receiving cold blood potassium cardioplegia. Patients were matched on the basis of preoperative ejection fraction (EF) and the number of anatomically similar stenotic coronary arteries. The adequacy of myocardial protection was assessed by serial perioperative determinations of radionuclide ventriculography, hemodynamic measurements, analyses of electrocardiograms and serum levels of MB-CK. We found that the level of myocardial protection was similar between unstratified groups. However, when subgroups were selected on the basis of prolonged aortic cross-clamp time (greater than ninety minutes) or impaired preoperative left ventricular function (EF less than 40%), there was a suggestion that cold blood cardioplegia may be advantageous.

Adult↗
PubMed1982

Extended endocardial resection for the treatment of ventricular tachycardia and ventricular fibrillation.

A total of 40 patients with drug-refractory, life-threatening cardiac rhythm disturbances--ventricular tachycardia in 23 patients and ventricular fibrillation in 17 patients--underwent extended endocardial resection (EER) of scar tissue. Scarring was due to myocardial infarction in 38 patients, to previous congenital heart operation in 1 patient, and to sarcoidosis of the heart in 1. The EER procedure was directed by epicardial and endocardial mapping data whenever possible, and was usually combined with revascularization, aneurysmectomy, or, in 5 patients, mitral valve replacement. Operative mortality was 10%, incident to poor preoperative ventricular function and hemorrhage secondary to previous cardiac surgical procedures. Thirty-three of the 36 survivors (92%) are free of arrhythmia at follow-up periods ranging from 3 to 36 months (mean, 12.5 months); the arrhythmia in the remaining 3 patients is now drug controlled. Thirty-three patients had postoperative electrophysiological studies, and in 30 (91%), the arrhythmia was no longer inducible. The results of surgical treatment for ventricular tachycardia and ventricular fibrillation were similar. The results also proved satisfactory whether the EER procedure was directed by visual observation or mapping.

Adolescent↗
PubMed1981

Nonrandomized matched pair analysis of intermittent ischemic arrest versus potassium crystalloid cardioplegia during myocardial revascularization.

The quest for the ideal method of myocardial preservation during coronary artery bypass graft (CABG) surgery continues at a rapid pace. Nevertheless, in the present clinical practice of cardiac surgery, the choice is chiefly between hypothermic intermittent ischemic arrest and hypothermic potassium cardioplegia. This study applies newer technics in radionuclear cardiology, as well as more conventional enzymatic, electrocardiographic, and hemodynamic determinations, to the evaluation of the effectiveness of the previously mentioned modes of myocardial protection. Serial assessments are made preoperatively as well as during the first ten days postoperatively. We find that the perioperative incidence of myocardial damage and changes in left ventricular performance are almost identical using either method in patients with relatively normal preoperative left ventricular performance who do not have severe preoperative refractory ischemia or necrosis.

Aged↗
PubMed1981

Serial assessment of left ventricular performance following coronary artery bypass grafting. Early postoperative results with myocardial protection afforded by multidose hypothermic potassium crystalloid cardioplegia.

Forty patients who recently underwent coronary artery bypass graft (CABG) operations had serial hemodynamic and scintigraphic studies. Multidose hypothermic potassium crystalloid cardioplegia was used for myocardial protection and newer techniques in anesthetic management and perioperative patient care were also employed. The method of equilibrium cardiac gated blood pool (GBP) scintigraphy was used to obtain perioperative changes in global ejection fraction (EF) and regional wall motion (RWM). Ninety percent of patients displayed a decrease in EF 2 hours postoperatively when compared to their preoperative values. This change was also associated with a fall in cardiac index (CI) and left ventricular stroke work index (LVSWI). Twenty-four hours postoperatively, EF and CI recovered to preoperative levels, but LVSWI remained depressed. Seven days postoperatively, global EF had improved to a value greater than the preoperative one (50% +/- 3% versus 57% +/- 4%, p < 0.05). Perioperative changes in RWM followed the same pattern as EF, but recovery in this index of regional contractility was faster than EF, since maximal improvement was observed 24 hours postoperatively. Thus transient left ventricular dysfunction is common immediately after CABG, but recent advances in myocardial protection and perioperative management are associated with short-term increases in regional and global left ventricular function documented by noninvasive GBP imaging.

Aged↗
PubMed1980

Early and long-term improvement in left ventricular performance following coronary bypass surgery.

Changes in left ventricular performance after coronary artery bypass grafting (CABG) have been variable. Earlier studies based on contrast left ventriculography have shown occasional improvement in left ventricular function in patients with unstable angina or abnormal preoperative ventricular performance, but for the most part repeat cardiac catheterization several months after operation has shown no significant changes in global left ventricular contraction. In the past few years, advances in radiopharmaceutical technology have made the characterization of left ventricular wall motion accurate and highly reproducible. Since prognosis in patients with coronary artery disease and survival after CABG have been related to global ejection fraction (EF), we employed prospectively on analysis of short-term and long-term changes in EF after CABG utilizing multidose hypothermic potassium crystalloid cardioplegia as the method of myocardial protection. Concomitantly, newer techniques in anesthesia and perioperative patient management were employed to minimize myocardial damage in these patients. Postoperative scintigraphic evaluation showed a transient (2-hour) depression in left ventricular function, followed by recovery to preoperative levels at 24 hours and significant improvement in EF at 7 days. From 7 days to 8 months postoperatively, there was no further change in resting EF, but there was another significant exercise-induced increase in EF at the long-term examination. Thus, present advances in the multidisciplinary management of patients with coronary artery disease are associated with improvement in resting and exercise-related EF postoperatively.

Aged↗