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Biomedical subjects

K W Burchard

Publications and source records attributed to K W Burchard.

At least 55 records · Page 3Linked to original sources
PubMed1986

Right atrial volume during hemorrhage in the dog.

Atrial B receptors elicit reflex changes after hemorrhage and respond to changes in atrial volume, but the latter have not been measured after hemorrhage. An impedance catheter that was originally designed to measure ventricular volume was advanced into the atrium from the femoral vein in each of 10 splenectomized dogs that were anesthetized with alpha-chloralose. The rate of hemorrhage and reinfusion was 2% of the estimated blood volume per min. Cardiac output (CO) was measured with dye dilution. The components of the atrial volume signal that were most sensitive to hemorrhage were the filling that occurred during late ventricular systole (Vs) and the absolute volume at the end of ventricular systole, (Vabs). Both variables were significantly less than base line (P less than 0.05) after 10% hemorrhage. The rate of change of Vs decreased significantly after 20% hemorrhage. However, the volume ejected with each atrial beat (Ve) decreased significantly (P less than 0.05) only after 30% hemorrhage. Atrial output (AO) as computed by multiplying Ve by heart rate (HR) did not change after hemorrhage. The ratio of AO to CO increased in direct proportion to HR (P less than 0.01) so that after 30% hemorrhage, for which HR was high, the decreases in CO from base line in individual dogs correlated significantly with the changes in AO (P less than 0.01). Since the B receptors are known to fire at the end of the ventricular systole at a rate that is dependent on blood volume, their firing may be a function of the concomitant atrial signals, Vs and Vabs, that are most sensitive to blood volume, and these atrial signals may serve as indexes of B fiber activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1986

Interaction of prostaglandins, activated complement, and granulocytes in clinical sepsis and hypotension.

Activated complement, thromboxane A2, prostacyclin, and activated granulocytes have been implicated in hemodynamic dysfunction after trauma, in sepsis, and in hypovolemic and septic shock. This study evaluated the interaction of plasma concentrations of complement components C3a and C5a, thromboxane B2 (TxB), prostaglandin 6-keto-F1 alpha (PGI), and granulocyte aggregation in clinical sepsis and hypotension. Forty-eight critically ill patients were followed clinically for as long as 10 days. Plasma C3a, C5a, TxB, and PGI were measured daily by the radioimmunoassay method. Granulocyte aggregation, the percentage of maximum aggregation of zymosan-activated plasma standard curves, was performed with patient plasma and normal human leukocytes. Patients were studied in four groups: group I, nonseptic, normotensive; group II, hypovolemic shock, group III, normotensive severe sepsis; and group IV, septic shock. Plasma from 12 normal adults was the control value. PGI, TxB, C3a, C5a, and granulocyte aggregation in patients were greater than that in the control subjects. Granulocyte aggregation was increased in groups III and IV versus groups I and II. C3a was increased in group IV versus groups II and III. C5a and TxB did not vary between groups. PGI was greatly increased in group IV compared with groups I through III. C3a and C5a decreased in nonsurvivors. PaO2/FiO2 ratios correlated directly with PGI and inversely with C3a and TxB/PGI. Plasma PGI and C3a are increased in septic shock. C3a and TxB/PGI imbalances are involved in hypovolemic and septic shock.

Adolescent↗
PubMed1986

Prostacyclin and thromboxane A2 in septic shock: species differences.

Prostacyclin and thromboxane A2 have been implicated as mediators of septic shock. Correlations between the human prostanoid response to sepsis and experimental paradigms are poorly understood. The purpose of this study was to compare changes in plasma levels of prostaglandin 6-keto-F1 alpha (PGI) and thromboxane B2 (TxB) during septic shock in Sprague-Dawley rats, domestic pigs, mongrel dogs, and man. Severe sepsis followed by septic shock (systolic BP less than 90 mmHg) was induced in rats by inoculation of 1.0 X 10(9) Aeromonas hydrophila, in pigs by graded IV infusion of 1.0 X 10(9)/ml A. hydrophila; and in dogs by an IV bolus injection of 5.0 X 10(9)/ml Escherichia coli. Plasma PGI and TxB (pg/ml) were measured by radioimmunoassay in control, septic, and septic shock experimental blood samples, and in normal controls, severly septic, and septic shock (systolic BP less than 90 mmHg) S.I.C.U. patients. Control, septic, and septic shock TxB levels in the dog and the pig were significantly greater than in the rat and man. PGI levels in the dog were significantly greater than in other species. TxB increased significantly in murine sepsis and PGI increased significantly in sepsis and septic shock. TxB increased during porcine sepsis and septic shock. In man, both PGI and TxB were significantly increased in severe sepsis, compared to normal controls, but only PGI was significantly higher in septic shock versus normotensive sepsis. Patterns of change in TxB/PGI ratios were similar for all species studied. Changes in PGI in the porcine septic experiments most closely paralleled those observed clinically.

Animals↗
PubMed1986

Trendelenburg versus PASG application--hemodynamic response in man.

Diminished venous return is the primary determinant of reduced cardiac output in hemorrhagic hypoperfusion. In this study the hemodynamic response of two therapies commonly employed to increase venous return in hemorrhagic hypoperfusion--pneumatic antishock garment (PASG) application and Trendelenburg (TREND) positioning--were compared in normovolemic man. Five patients had PASG pressure of 20 mm Hg compared with 10 degrees Trendelenburg, eight patients had 20 and 40 mm Hg PASG application compared with 10 degrees Trendelenburg. PASG application at both 20 and 40 mm Hg resulted in a significant increase in CVP (11.1 +/- 1.9 baseline to 16.0 +/- 2.7 PASG 40; p less than 0.01) left atrial pressure (LAP) (10.1 +/- 1.3 baseline to 14.4 +/- 1.8 PASG 20; p less than 0.01) pulmonary capillary wedge pressure (PCWP) (11.6 +/- 2.0 baseline to 16.8 +/- 3.4 PASG 40; p less than 0.01) and esophageal pressure (Pes) (5.0 +/- 0.8 baseline to 8.6 +/- 0.9 PASG 40; p less than 0.01). However, transmural right and left atrial pressure (RATP, LATP) and cardiac index (CI) were unchanged. Ten degrees of Trendelenburg resulted in no increase in CVP, PCWP, RATP, or LATP, but CI (2.67 +/- 0.07 baseline to 2.82 +/- 0.1 TREND; p less than 0.01) was significantly increased. Systemic vascular resistance index (570 +/- 46 TREND vs. 668 +/- 53 PASG 40; p less than 0.01) was significantly less in Trendelenburg compared to PASG at 40 mm Hg. The data demonstrate that elevation in CVP, LAP, and PCWP following PASG application is secondary to an increase in intrathoracic pressure (as measured by Pes).(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗
PubMed1986

Enterobacter bacteremia in surgical patients.

The records of 63 surgical patients with one or more positive blood cultures for Enterobacter organisms were reviewed to determine clinical, epidemiologic, and mortality risk factors. Enterobacter bacteremia occurred, on the average, on the twenty-third day of hospitalization, most frequently in male patients (47), after antibiotic therapy (48 patients), placement of central venous catheters (38 patients), gastrointestinal tract operations (36 patients), and respiratory failure (31 patients). Portals of entry were most commonly sputum (25 patients), open skin wounds (16 patients), and central venous lines (12 patients). Mortality risk (22 patients, 35%) was increased with Enterobacter bacteremia occurring after the fifteenth day of hospitalization (18 of 45 patients versus 4 of 28 patients, p less than 0.01), a preceding Enterobacter focus (13 of 22 patients versus 9 of 41 patients, p less than 0.05), preceding non-Enterobacter bacteremia (10 of 15 patients versus 12 of 48 patients, p less than 0.02), preceding total parenteral nutrition (11 of 21 patients versus 11 of 42 patients p less than 0.01), respiratory failure (19 of 36 patients versus 3 of 27 patients p less than 0.01), and renal failure (11 of 12 patients versus 11 of 51 patients p less than 0.01). The mortality risk was not diminished by specific antibiotic therapy. Enterobacter is emerging as an important pathogen in surgical patients. Prolonged antibiotic administration, particularly that of cephalosporins, may promote Enterobacter colonization of the tracheobronchial tree and skin with subsequent invasion enhanced by respiratory failure, open skin wounds, or central venous catheters traversing the skin. Mortality risk is determined primarily by factors associated with critical illness rather than effects of Enterobacter organisms and their specific treatment.(ABSTRACT TRUNCATED AT 250 WORDS)

Cross Infection↗
PubMed1985

Enterococcal bacteremia in surgical patients.

In 73 surgical patients enterococcal bacteremia was preceded by antibiotic administration (n = 58), central venous catheters (n = 52), other-organism bacteremia (n = 44), and gastrointestinal tract operations (n = 41). Surgical wounds and urinary tract infections were the most frequent portal of entry. The overall mortality was 42%. The mortality risk was significantly greater in patients with preceding or concomitant gram-positive bacteremia and four or more days of cephalosporin administration prior to enterococcemia. In 21 patients who had been given cephalosporins and who had gram-positive bacteremia, specific antienterococcal therapy resulted in survival in five of nine patients, compared with three of 12 who survived without therapy. Enterococcal bacteremia in surgical patients follows antibiotic administration, central venous catheter use, other-organism bacteremia, and intra-abdominal operations. Preceding or concomitant gram-positive bacteremia defines a subgroup of patients with high mortality who seem to respond to antienterococcal therapy.

Adult↗
PubMed1985

Thromboxane and prostacyclin in clinical acute respiratory failure.

Plasma levels of thromboxane A2 and prostacyclin have been elevated during experimental acute respiratory failure (ARDS). The present study evaluates the relationship of plasma levels of thromboxane A2 and prostacyclin, measured by radioimmunoassay as the stable metabolites thromboxane B2 (TxB) and prostaglandin 6-K-F1 alpha (PGI) to the incidence of clinical ARDS. Sixty-seven consecutive patients at risk for ARDS were studied prospectively. TxB, PGI, platelet, and leukocyte counts were measured daily for up to 5 days. Of 55 patients without cerebral injury, 25 (45%) developed ARDS, and 30 did not. Of 12 patients with cerebral injury, none developed ARDS. This difference was highly significant (P less than 0.01). TxB was increased and age lower with head injury (P less than 0.05). PGI was significantly lower in ARDS (110 +/- 32 vs 227 +/- 211 pg/ml, P less than 0.05), and mean TxB was unchanged. TxB was increased in age greater than 60 and decreased with prostaglandin inhibitors. ARDS was significantly associated with TxB greater than 70 pg/ml, PGI below the detectable level of 103 pg/ml, TxB/PGI ratio greater than 0.7, and age greater than 60 years. Peak TxB occurred before or simultaneously with onset of ARDS in 68%. Leukocytes were decreased in ARDS (8.6 +/- 4 vs 11.1 +/- 4.4 X 10(3)/mm3) and platelets were unchanged. ARDS was decreased with steroid therapy. Elevated TxB is related to a high incidence of ARDS. Elevated PGI may protect against ARDS. Cerebral injury patients in this study were resistant to ARDS in spite of increased TxB.

6-Ketoprostaglandin F1 alpha↗
PubMed1985

Adverse effects of hypothermia in postoperative patients.

The effect of intraoperative and postoperative temperature on morbidity, mortality, and other clinical risk factors was evaluated in 100 consecutive general surgical patients admitted postoperatively to a surgical intensive care unit. Hypothermia (temperature less than 97 degrees F) was present in 77 percent of the patients intraoperatively, in 53 percent at the end of surgery, and in 21 percent at 4 hours. Mortality was increased with patient age greater than 55 years, emergency surgery, operative blood pressure less than 100 mm Hg, operative fluid requirements greater than 1,500 ml/hour, temperature less than 97 degrees F at 2, 4, and 8 hours postoperatively, and presence of postoperative complications. Intraoperative fluid requirements were significantly greater for patients with mortality risk factors. Patients over 55 years of age were more often hypotensive and hypothermic than younger patients, but mortality was increased only for patients less than 55 years of age with a temperature of less than 97 degrees F at 8 hours or an operative blood pressure of less than 100 mm Hg. Mortality after general surgical procedures is increased with operative hypotensive and prolonged postoperative hypothermia. Hypothermic patients with mortality risk factors should be aggressively rewarmed postoperatively.

Female↗
PubMed1985

Hypercalcemia in critically ill surgical patients.

Critical surgical illness, commonly accompanied by shock, sepsis, multiple transfusions, and renal failure, is usually associated with low total calcium and/or low or normal ionized calcium. A seminal case of hypercalcemia in a surgical intensive care unit (SICU) patient prompted the review of 100 patients with longer than average SICU days (greater than 12) to determine the incidence, associated factors, and possible etiologies of this condition. Ten patients had elevated measured, and five others had elevated calculated, ionized calcium (5.9 +/- 0.25 mg%), an incidence of 15%. Compared to the 85 patients who did not develop hypercalcemia, this population had a significantly higher frequency of the following: renal failure, dialysis, total parenteral nutrition (TPN) usage greater than 21 days, bacteremic days greater than 1, transfusions greater than 24 units, shock greater than 1 day, SICU days greater than 36, and antibiotics used greater than 7. In addition, this group had significantly more days of hypocalcemia early in their hospital course. There was no difference in sex, age, mortality, or incidence of respiratory failure. Two patients studied in depth had renal failure requiring dialysis and no malignancy, milk-alkali syndrome, hyperthyroidism, or hypoadrenalism. Parathormone (PTH) concentrations were high normal or elevated (N terminal 20 and 21 pg/ml; C terminal 130 microliters Eq/ml and 1009 pg/ml) at the time of elevated calcium (total 9.2 to 14.6 mg%; ionized 4.9 to 8.2 mg%). Immobilization does not increase PTH. In renal failure, PTH elevation is a consequence of hypocalcemia rather than hypercalcemia. Moreover, five patients did not have renal failure. Shock, sepsis, and multiple transfusions containing citrate may lower total and/or ionized calcium and thus stimulate PTH secretion. Whatever the mechanism, approximately 15% of critically ill surgical patients develop hypercalcemia, which may represent a new form of hyperparathyroidism.

Acute Kidney Injury↗
PubMed1985

Trendelenburg versus PASG application in moderate hemorrhagic hypoperfusion.

In hemorrhagic hypoperfusion one of the therapeutic goals of pneumatic antishock garment (PASG) application is to increase cardiac output, presumably by augmenting venous return from below the diaphragm, an effect expected to be similar to Trendelenburg positioning. The purpose of this study was to compare the hemodynamic response of these two common therapeutic interventions in hemorrhagic hypoperfusion. Five anesthetized dogs were bled over 10 minutes 24% of measured blood volume on two separate days. At the beginning of hemorrhage, they randomly received either PASG application or Trendelenburg positioning. PASG pressures of 30 +/- 5 mm Hg were applied to produce an inferior vena cava pressure of 10-15 mm Hg. Such PASG pressure had been shown previously to not diminish cardiac output from PASG application. Mean arterial pressure was maintained throughout the experiment with both therapies. With PASG application, cardiac index was depressed and systemic vascular resistance was elevated at 10, 20, and 30 minutes following hemorrhage. In contrast, Trendelenburg therapy maintained cardiac index and produced no significant increase in systemic vascular resistance index. Thus Trendelenburg therapy preserved mean arterial pressure primarily by maintaining cardiac output, probably by increasing venous return, whereas PASG application preserved mean arterial pressure primarily by increasing systemic vascular resistance. For treatment of moderate hemorrhagic hypoperfusion, Trendelenburg positioning may be superior therapy to PASG application.

Animals↗
PubMed1985

Positive pressure respirations and pneumatic antishock garment application--hemodynamic response.

Pneumatic antishock garment (PASG) application has been recommended for treatment of hypovolemic hypotension and intraperitoneal or retroperitoneal hemorrhage. Often these patients require positive pressure respiration (PPR). This study measured the hemodynamic response of low pressure PASG application, with and without PPR, in normovolemic man and the effects of PASG application on serum lactate. Ten patients after coronary artery bypass surgery were studied with PPR and PASG application (3 to 20 hours post-surgery), and PASG alone (24 to 30 hours post-surgery). PASG pressures of 0,5,10,20, and 0 mm Hg were applied for 10 minutes each after which LAP, PCWP, CVP, mean arterial pressure, heart rate, cardiac index, and serum lactate level were measured. PASG application produced significant elevations in right and left ventricular filling pressures. The left ventricular filling pressure response was significantly less with positive pressure respiration. The CVP and LAP increase did not result in a greater cardiac index. Serum lactate levels rose slightly during PASG application. Low-pressure PASG application results in an 'autotransfusion' effect which is greater without PPR.

Blood Pressure↗
PubMed1985

Positive end expiratory pressure with increased intra-abdominal pressure.

Positive pressure ventilation with PEEP may be required in patients with increased IAP. Separately, PEEP and increase IAP have been shown in both man and animals to have significant hemodynamic effects. The results of this study demonstrated that, in dogs, the combination of PEEP with elevated IAP results in markedly increased CVP, PCWP, mean PAP and PVR. CO is depressed but to no greater degree than with the combination of IAP and positive pressure ventilation without PEEP. Interestingly, serum lactate levels markedly increase when both PEEP and IAP are applied, a finding not explained by the fall in CO. Possibly, the combination of PEEP with elevated IAP inhibits hepatic metabolism of lactate. Measures taken to reduce IAP and PEEP may not only improve hemodynamics but may result in reduced serum lactate levels.

Abdomen↗
PubMed1985

Thromboxane, prostacyclin, and the hemodynamic effects of graded bacteremic shock.

This study investigates the interaction of thromboxane, prostacyclin, and the hemodynamic dysfunction of graded bacteremia. Arterial, venous, and pulmonary artery catheters were inserted into eight adult female pigs under barbiturate anesthesia. After a 60-min control period Aeromonas hydrophila (1.0 X 10(9)/ml) was infused intravenously at 0.2 ml/kg/hr, increasing gradually to 4.0 ml/kg/hr at 4 hr. Hemodynamic measurements, blood gases, and radioimmunoassay of thromboxane B2 (TxB) and prostaglandin 6-keto-F1 (PGI) were performed during the control period, at 10, 20, 30, 45, 60, 75, and 90 min of bacteremia and at 30-min intervals thereafter. During the bacterial infusion, cardiac index (CI), mean arterial pressure (MAP), paO2, pvO2, stroke volume (SV), and left ventricular stroke work (LVSW) decreased significantly, and pulmonary vascular resistance (PVR), pulmonary artery pressure (PAP), and intrapulmonary shunt (Qs/Qt) increased significantly. TxB was significantly increased at 30 min and remained elevated thereafter. PGI did not rise above control levels until after 240 min of bacterial infusion. TxB cross-correlated most frequently with CI, PVR, SV, paO2, and Qs/Qt, changes in TxB preceding the other variables by 0-60 min. PGI cross-correlated significantly with MAP, LVSW, CI, paO2, and Qs/Qt, changes in PGI preceding MAP, LVSW, and CI by 0-60 min, but following paO2 and Qs/Qt by 30-60 min. TxB is increased early in graded bacteremia and appears related to cardiorespiratory dysfunction. PGI increases late in graded bacteremia, following the onset of respiratory failure, and may mediate the arterial hypotension of septic shock.

6-Ketoprostaglandin F1 alpha↗
PubMed1984

Staphylococcus epidermidis sepsis in surgical patients.

We examined 58 surgical patients with two or more blood cultures positive for Staphylococcus epidermidis to determine factors associated with risk, mortality, and invasive sepsis. Bacterial sepsis was associated with gastrointestinal (GI) operations, total parenteral nutrition, and a regimen of two or more parenteral antibiotics. Mortality was 46% overall and significantly increased with age greater than 50 years, GI operations, other gram-positive sepsis, recurrent sepsis (positive blood culture 24 hours or more after the first blood culture), and the presence of organisms sensitive to three or less antibiotics. Antibiotic therapy appropriate for more than 50% of the S epidermidis organisms cultured from each patient resulted in significant reduction in mortality. Staphylococcus epidermidis should be considered a significant pathogen in critically ill surgical patients. Invasive S epidermidis sepsis can be recognized and requires specific antibiotic therapy.

Adolescent↗
PubMed1984

Tumor embolism as the first manifestation of cancer.

Major tumor emboli (obstructing segmental or larger branches of the pulmonary artery) are a rare mechanism of spread of cancer to the lungs. Less frequently are tumor emboli the cause of respiratory failure and death. The present case of major tumor embolism as the initial manifestation of cancer is unusual for the chronicity, documentation of recurrence, and tissue pathology encountered. In retrospect, we can describe clues which may arouse suspicion of tumor embolism in future cases.

Bone Neoplasms↗
PubMed1984

Thromboxane interaction with cardiopulmonary dysfunction in graded bacterial sepsis.

The relationship between plasma levels of thromboxane A2, radioimmunoassayed as thromboxane B2 (TxB), and cardiopulmonary dysfunction in graded bacterial sepsis was investigated. Five adult female pigs under anesthesia were intubated and allowed to breathe room air spontaneously. Femoral arterial, venous, and pulmonary artery catheters were inserted. After a 60-minute control period Aeromonas hydrophila (1.0 X 10(9)/ml) was infused intravenously at 0.2 ml/kg/hr, gradually increasing to 4.0 ml/kg/hr over 4 hours. Arterial and mixed venous blood gases, hemodynamic measurements, and TxB plasma concentrations were obtained during the control period, at 10, 20, 30, 45, and 60 minutes and at 30-minute intervals thereafter. Cardiac index increased significantly from control at 20 minutes, remained above control levels for 1 hour, and then declined to significantly low values at 150 minutes. TxB was increased from control at 20 minutes, rising to four times control at 120 minutes. Mean arterial pressure, pulmonary capillary wedge pressure, left ventricular stroke work, paO2, and pvO2 decreased significantly during the experiment. Pulmonary artery pressure and pulmonary vascular resistance increased significantly. Changes in TxB were significantly cross-correlated with changes in cardiac index, pulmonary vascular resistance, stroke volume, left ventricular stroke work, and paO2. TxB elevations led the cross-correlated variables by 0 to 60 minutes. Pulmonary vascular resistance cross-correlated with mean arterial pressure and cardiac index. TxB is increased early in graded bacterial sepsis. Changes in TxB appear to precede impaired cardiopulmonary function. The data suggest that TxB is involved in the detrimental hemodynamic effects of early septicemia.

Animals↗