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Biomedical subjects

J P Rasmussen

Publications and source records attributed to J P Rasmussen.

At least 19 recordsLinked to original sources
PubMed1989

Effect of methylprednisolone on endotoxemia and complement activation during cardiac surgery.

The influence of high doses of methylprednisolone on complement activation and endotoxin concentration was investigated in two groups of eight patients undergoing coronary artery bypass grafting. Group 1 received methylprednisolone, 30 mg/kg, at the induction of anesthesia; group 2 served as the control group. The endotoxin concentrations increased significantly in both groups at the start of cardiopulmonary bypass. During cardiopulmonary bypass, the endotoxin concentrations were significantly higher in the steroid group compared with the control group (p less than 0.01). After completion of surgery, the endotoxin concentrations declined to almost zero within seven days in both groups. Complement activation was significantly reduced in the steroid-treated group during cardiopulmonary bypass compared with the control group (P less than 0.01). The clinical outcome after the first postoperative week was the same in the two groups. It appears that high-dose steroids can reduce complement activation during cardiopulmonary bypass, although the clearance of endotoxins may also be reduced.

Aged↗
PubMed1989

Endotoxemia and enhanced generation of oxygen radicals by neutrophils from patients undergoing cardiopulmonary bypass.

Plasma endotoxin concentrations and oxidative burst response of peripheral blood polymorphonuclear leukocytes were examined in 12 patients undergoing coronary artery bypass. The measurements were made just before the operation, 5 minutes after removal of the aortic crossclamp, and 24 hours after the operation. Endotoxin was quantitated by a combination of a sensitive Limulus amebocyte lysate assay and rocket immunoelectrophoresis measuring picogram amounts of endotoxin. Peripheral blood neutrophils were purified by a two-step dextran sedimentation and metrizoate sodium Ficoll (Lymphoprep., Nyegaard, Oslo, Norway) centrifugation. The oxidative burst response of these cells was measured for their ability to generate superoxide anion and was determined by a cytochrome c reduction assay. Preoperatively, all the plasma samples except one were free of endotoxin. The endotoxin levels reached 100 pg/ml 5 minutes after removal of the aortic crossclamp, and except in one sample they had decreased 24 hours after the operation. Studies on the generation of superoxide by neutrophils showed a decline in the response 5 minutes after removal of the aortic crossclamp and an enhancement of the response to f-Met-Leu-Phe by cells obtained from 11 of 12 patients 24 hours postoperatively. In vitro addition of bacterial lipopolysaccharide to blood from healthy individuals also enhanced the superoxide response of the neutrophils. We conclude that during cardiopulmonary bypass the circulating blood is contaminated by endotoxin and the neutrophils are primed for enhanced generation of oxygen radicals. The released oxygen radicals may be involved in the tissue damage observed in these patients.

Aged↗
PubMed1987

Presence of circulating endotoxins during cardiac operations.

Ten patients having coronary artery bypass grafting were intraoperatively and postoperatively analyzed for endotoxins with the Limulus amoebocyte lysate test. A new highly sensitive rocket immunoelectrophoretic assay for reading the reactions of endotoxins with Limulus amoebocyte lysate was used. Preoperatively, all blood samples from the patients had negative Limulus amoebocyte lysate tests, negative blood cultures, normal total white cell counts, and were clinically without signs of infection. Intraoperatively, a substantial amount of endotoxins were found in samples from the extracorporeal circuit, the pulmonary artery, and the cardiac suction lines, which persisted during the cardiopulmonary bypass. The endotoxin content decreased significantly (p less than 0.05) 6 hours after cardiopulmonary bypass and further decreased within the seventh postoperative day (p less than 0.01). A positive Limulus amoebocyte lysate test was also found in some of the fluids administered during the operation, that is, the cardioplegic fluids, the priming fluids for the extracorporeal circuit, the blood transfusions, and the ice for local cooling. Postoperatively, all patients had rectal temperatures below 38.5 degrees C, but no correlation was found between the magnitude of endotoxin content and the degree of fever. Only one of the patients had positive blood cultures. Despite the measured endotoxin content, no intraoperative or postoperative complications were found.

Aged↗
PubMed1986

PEEP reverses nitroglycerin-induced hypoxemia following coronary artery bypass surgery.

Intravenous nitroglycerin is increasingly used during and after cardiac surgery to control blood pressure and improve subendocardial and peripheral circulation. A dramatic decrease in arterial oxygenation has, however, been reported in a number of poorly controlled clinical trials. In the present investigation 16 patients were studied 2-4 h after coronary artery bypass procedures. All were treated with a continuous infusion of nitroglycerin (1 microgram X kg-1 X min-1). Utilizing an on-off-on drug design, it was clearly established that nitroglycerin depresses arterial oxygenation by increasing the pulmonary venous admixture. Three possible underlying mechanisms are discussed, but at the present time no firm conclusion can be drawn as to the nature of the changes. Eight patients were ventilated with 1 kPa (10 cmH2O) positive end-expiratory pressure (PEEP) during the nitroglycerin infusion. PEEP-ventilation reversed nitroglycerin-induced changes in arterial oxygenation and pulmonary shunting without adversely affecting hemodynamic stability.

Coronary Artery Bypass↗
PubMed1985

Hemodynamic effects of alfentanil in verapamil-treated dogs.

The hemodynamic effects of alfentanil were investigated in six dogs receiving verapamil 0.5 mg X kg-1 and six dogs receiving saline in equal volume. Basic measurements were done after 30 min and the dogs were then given alfentanil 160 micrograms X kg-1 with measurements at 5, 15, and 30 min. Significant increases in central venous pressure (CVP), mean pulmonary arterial pressure and pulmonary wedge pressure (PWP) were found 30 min after verapamil. After verapamil-alfentanil, increases were seen in CVP and PWP at 5 and 15 min and in PWP at 30 min. Mean arterial pressure and cardiac index were unchanged, while a decrease in heart rate was fully compensated by an increase in stroke volume. Indices of contractility were unchanged. All values were within the limits of normal hemodynamic function. We conclude that high-dose alfentanil has no adverse effects on hemodynamic parameters during calcium blockade.

Alfentanil↗
PubMed1978

Cardiac function and hypercarbia.

In 12 patients with heart disease, hypercarbia was induced for carotid endarterectomy. Anesthesia was maintained with nitrous oxide in oxygen and methoxyflurane. In addition to intra-arterial measurements of blood pressure, cardiac output, systolic time intervals (STI), and pressure time indices (PTI) were determined in order to assess cardiovascular responses in these patients. Internal carotid stump blood pressure was measured in five patients before and after induction of hypercarbia. Mild elevation of the Paco2 level affected systolic time intervals but not heart rate and blood pressure. When Paco2 levels reached 56 to 65 torr, systolic but not diastolic blood pressure rose significantly, heart rate and cardiac output increased, while the shortening in the preejection period (PEP), left ventricular ejection time (LVET), and the decrease in the PEP/LVET ratio signified increased mechanical cardiac activity. Hypercarbia caused intense sympathetic stimulation as demonstrated by twofold to threefold increases in plasma catecholamine levels. Stump blood pressure was elevated. Cardiac oxygen demand was significantly increased, while coronary filling time was shortened, as indicated by the increase in the tension time index and shortening in the diastolic time. This signified a relative myocardial underperfusion. Thus, while hypercarbia to levels of 66 to 70 torr increased internal carotid artery stump pressure, it also caused increased cardiac mechanical activity and concomitant unfavorable balance between myocardial oxygen consumption and supply. The measurement of STI and the computation of PTI provided early detection of alterations in cardiac function.

Aged↗
PubMed1978

Cardiac function during induction and early anesthesia with methoxyflurane. An evaluation using systolic time intervals and pressure time indices.

In addition to the standard monitoring of heart rate and blood pressure, the Systolic Time Intervals were used to evaluate cardiac performance, and the Pressure Time Indices (tension time index = TTI; diastolic pressure time index = DPTI) were used to estimate myocardial oxygen balance. Twelve patients with known heart disease were studied during induction with thiopental, intubation, and early anesthesia with methoxyflurane. Cardiac performance diminished after thiopental; and during methoxyflurane it was reflected in increases in pre-ejection period (PEP) and the ratio PEP/LVET. Intubation resulted in a hyperactive state of the heart, as shown by maximal decreases in PEP and PEP/LVET. Myocardial oxygen balance--estimated from the supply/demand ratio (DPTI/TTI)--was impaired after thiopental. After intubation, DPTI/TTI decreased to its lowest value due to an excess of myocardial oxygen demand (TTI) over myocardial oxygen supply (DPTI), signifying a transitory underperfusion of the subendocardium. During methoxyflurane the oxygen balance was gradually restored towards control value. The Systolic Time Intervals and the Pressure Time Indices provided valuable information on cardiac function not available from standard monitoring alone.

Adult↗
PubMed1977

Postoperative pulmonary function in obese patients after upper abdominal surgery.

The pulmonary course after jejuno-ileal by-pass operation in six massively obese patients (mean weight 130.2 kg) was followed for the first 5 postoperative days by means of arterial blood gas analysis and measurements of forced vital capacity (FVC), forced expired volume in the first second (FEV1.0) and peak expiratory flow rate (PEFR). The patients were extubated in the operating room and were breathing spontaneously in the postoperative period. Pao2 and FVC reached their minimum values in the first 24 postoperative hours (respectively, 74% and 45% of their preoperative values), but were almost restored in 5 days. PEFR had at this time reached 77% of its preoperative value FEV1.0% (FEV1.0%in per cent of FVC) did not change from the pre- to the postoperative period, but remained about 70%.

Adult↗
PubMed1977

Evaluation of impedance cardiography druing anesthesia in extremely obese patients.

In three anesthetized markedly obese patients, non-invasive stroke volumes (the transthoracic electrical impedance method) were compared to simultaneously obtained invasively measured stroke volumes (dye-dilution method). Close correlations were obtained (r = 0.90--0.98) between the two methods, although constant lower impedance stroke volumes were found in these patients when the values usually employed for the electrical resistivity of the blood (zeta) were used for calculation of the impedance stroke volume. No statistically significant difference (P greater than 0.10) between the two methods was found when a zeta of 175 ohm X cm was used for the calculations, or when the percentage changes in stroke volumes were analyzed. The impedance method is safe and reliable; it also permits non-invasive measurements of stroke volume during anesthesia in markedly obese patients.

Anesthesia↗
PubMed1977

Pulmonary function in obese patients scheduled for jejuno-ileostomy.

Preoperative pulmonary parameters were evaluated in 37 extremely obese but otherwise healthy patients. They were on average 100.9% overweight. X-ray of the chest, electrocardiograms, and residual volume, vital capacity, total lung capacity, maximum breathing capacity, forced expired volume in 1 second, and related ratios were all within the normal range. The alveolar-arterial oxygen gradient and the arterial carbon dioxide tension were also within the normal range. The only abnormal finding was a substantially reduced arterial oxygen tension. It is suggested that the measurement of functional residual capacity, closing volume, and the slope of the alveolar plateau (phase III in the single breath nitrogen washout technique) might give more valuable information.

Adult↗
PubMed1977

Continuous measurement of the oxygen tension in blood. A comparative study in the dog.

An equipment constructed by the International Biophysics Corporation, the Differential Oxygen Analyzer, which was designed for continuous recording of the oxygen tension in the blood, particularly during extracorporeal circulation, was tested. It proved to react rather slowly to changes in the PO2 and the magnitude of the error of the single measurements is far too high at the present stage of development.

Animals↗
PubMed1976

On-line systolic time intervals during anesthesia in patients with and without heart disease.

Twenty-four patients with severe, 24 with moderate, and 24 without heart disease were selected for measurements of systolic time intervals (STI) and blood pressure before and during anesthesia. In all patients anesthesia was induced with thiopental, 4 mg/kg. After tracheal intubation, 12 patients from each heart-disease class received halothane-N2O-O2 (halothane) and 12 patients from each class morphine-d-tubocurarine-N2O-O2 (MS-dTc). Thiopental increased the pre-ejection period (PEP), decreased left ventricular ejection time (LVET), and accelerated heart rate (HR). These changes were similar in patients with and without heart disease. Halothane and and MS-dTc lowered systolic blood pressure and increased PEP/LVET. With halothane but not with MS-dTc these changes were more pronounced in patients who had heart disease. Changes of the PEP/LVET ratio during halothane anesthesia were a better discriminating variable among patients without, with moderate, and with severe heart disease than were changes in systolic blood pressure.

Adult↗
PubMed1976

Changes in cardiac function during and after pregnancy expressed by systolic time intervals.

Hemodynamic changes during the first and third trimester in pregnancy and in the first week of puerperium were evaluated by non-invasive measurements of Systolic Time Intervals (STI) in supine and left lateral position. The Pre-ejection Period (PEP) was found to shorten significantly in pregnancy and the puerperium due to the increased blood volume. The electro-mechanical systole (QS2) and left ventricular ejection time (LVET) were shortened too, while PEP/LVET-ratio was increased in the third trimester due to the mechanical compression of the gravid uterus on the inferior vena cava. A lengthening of QS2 and LVET and a decreased PEP and P/L-ratio were demonstrated in the third trimester in lateral position when the pressure of the enlarged uterus was eliminated. Heart rate (HR) increased in late pregnancy as well as after delivery, while arterial blood pressure (BP) only underwent minor changes. Employment of the STI seems to provide more useful information about the changes cardiac function during gestation than HR and BP does. The measurements of STI can be repeated without any risk or inconvenience to the patients.

Adult↗