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Biomedical subjects

E R Schmid

Publications and source records attributed to E R Schmid.

At least 37 records · Page 2Linked to original sources
PubMed1999

Continuous thermodilution cardiac output: clinical validation against a reference technique of known accuracy.

OBJECTIVE: To evaluate the accuracy and precision of continuous thermodilution (CCO) by using a validated bolus thermodilution (BCO) reference technique as criterion standard. DESIGN: Under circulatory steady state conditions, a CCO system (Vigilance, software versions 4.35 and 4.39) was validated with regard to CCO as well as iced and room temperature BCO. SETTING: Intensive care unit at a university hospital. PATIENTS: Method comparison was conducted in 56 cardiac surgical patients, 28 patients being allocated to one of the two software versions, and 14 within each group to either iced or room temperature BCO. MEASUREMENTS AND RESULTS: CCO readings were registered in duplicate before and after three to five bolus injections conducted with both the Vigilance and reference systems. Iced BCO showed excellent agreement between the Vigilance and reference systems, yielding SDs of bias of 0.41 and 0.37 l/min and linear correlation coefficients (r) of 0.97 and 0.96. With room temperature BCO, agreement was significantly less. CCO, irrespective of software version, showed higher SDs of bias (0.90 and 0.84 l/min) and lower r values (0.84 and 0.81) than iced BCO (p < 0.0001). CCO measurements with software version 4.39 yielded a similar SD of bias to that with room temperature BCO. CONCLUSION: Decreased precision of CCO as compared to iced BCO may, in clinical settings, be outweighed by the advantages of automated and continuous monitoring. Under research conditions, however, iced BCO remains the method of choice.

Adolescent↗
PubMed1999

Treatment of left atrial dissection after mitral repair: internal drainage.

Two patients with intraoperative dissection of the entire left atrium after mitral valve repair are presented. Intraoperative transesophageal echocardiography detected left atrial dissection with formation of a large cavity compressing the left atrium. The false lumen was opened and widely connected to the right atrium to perform the decompression. This technique permits the runoff into the low pressure system in case of persisting hemorrhage from the unknown entry, and eliminates the risk of systemic embolization from the cavity.

Aortic Dissection↗
PubMed1999

Transesophageal echocardiographic area and Doppler flow velocity measurements: comparison with hemodynamic changes in coronary artery bypass surgery.

OBJECTIVE: Changes in transesophageal echocardiography (TEE)-derived Doppler flow velocities through the mitral valve and pulmonary veins occur after cardiopulmonary bypass and are believed to reflect left ventricular (LV) diastolic functional impairment. The aim of this study was to determine the time-coincidence between these Doppler flow velocity parameters, LV two-dimensional (2D) short-axis area measurements, and hemodynamic parameters in patients after coronary artery bypass grafting. DESIGN: Prospective clinical study. SETTING: University hospital. PARTICIPANTS: Twenty patients with normal ejection fraction undergoing elective cardiac surgery. INTERVENTIONS: At multiple intervals during surgery and 6 hours postoperatively, mitral inflow velocity and pulmonary venous flow velocity were measured with pulsed Doppler TEE. LV short-axis area by echocardiography and cardiac output by thermodilution were simultaneously obtained. MEASUREMENTS AND MAIN RESULTS: Time-coincidence was found in the immediate postbypass period between a decreased E/A ratio from 1.16 (95% confidence interval, 1.0 to 1.31) to 0.64 (95% confidence interval, 0.47 to 0.81, p < 0.01), a decreased E-wave deceleration time, and a significantly increased heart rate (HR) and cardiac index. End-diastolic area (EDA) and stroke volume index (SVI) decreased after sternal closure. HR, E-wave deceleration time, and SVI remained altered until 6 hours postoperatively. No change was found in pulmonary venous flow velocity parameters and systolic LV function. CONCLUSION: In patients with normal systolic ventricular function and no inotropic support, Doppler flow velocity patterns alone did not sufficiently reflect hemodynamic changes, whereas 2D LV area, especially EDA measurements, provided useful information about hemodynamically significant LV filling impairment.

Aged↗
PubMed1999

Emergency repair of incidentally diagnosed ascending aortic aneurysm immediately after caesarean section.

A 36-yr-old pregnant woman with a history of hypertension presented at term for elective Caesarean section because of breech position. At preoperative examination, a diastolic murmur was found and transoesophageal echocardiography (TOE) revealed a large, 8.1-cm diameter ascending aortic aneurysm with severe aortic regurgitation and moderate pericardial effusion. Surgical repair was not considered to be urgently required. The patient was delivered electively by Caesarean section under epidural anaesthesia using invasive arterial pressure monitoring. TOE performed 6 h post-partum showed progressing pericardial effusion, for which emergency replacement of the aortic valve and ascending aorta were indicated. The epidural catheter was removed 4 h before starting the cardiopulmonary bypass procedure. Arterial pressure was controlled by a titrated infusion of esmolol and clonidine. To improve uterine tone, the patient received an i.v. infusion of oxytocin throughout surgery. After implantation of an aortic composite graft and weaning from cardiopulmonary bypass, the patient was transferred to the intensive care unit. Awake and receptive to neurological evaluation, her trachea was extubated 4 h after surgery. Mother and baby made an uneventful recovery.

Adult↗
PubMed1999

Factors influencing the individual effects of blood transfusions on oxygen delivery and oxygen consumption.

OBJECTIVE: To determine factors influencing the individual effects of blood transfusions regarding oxygen delivery and consumption. DESIGN: Chart review. SETTING: A university hospital cardiosurgical intensive care unit. PATIENTS: Sixty-seven patients with 170 transfusion events evaluated. INTERVENTIONS: Blood transfusion. MEASUREMENTS AND MAIN RESULTS: Measurements were performed before and after a blood transfusion, separated by 302 +/- 13 mins (mean +/- SEM). The individual increase in cardiac index resulting from a blood transfusion was inversely related to cardiac index before transfusion (p < .001), oxygen delivery index before transfusion (p < .001), and oxygen consumption index before transfusion (p < .001). The individual increase in oxygen delivery index was inversely related to oxygen consumption index before transfusion (p < .001). The individual increase in oxygen consumption index was inversely related to oxygen consumption index before transfusion (p < .001). Individual changes in cardiac index, oxygen delivery index, and oxygen consumption index were not significantly related to preoperative ejection fraction (25%-87%), age (32-81 yrs), and pretransfusion hemoglobin concentration (5.0-11.8 g/dL). CONCLUSION: In adult patients after cardiovascular surgery, oxygen delivery- and oxygen consumption-related variables predict the individual response to blood transfusions better than do patient characteristics such as preoperative ejection fraction, age, and pretransfusion hemoglobin concentration. Including oxygen delivery and oxygen consumption, variables into the transfusion decision, thus, may enable a more individual use of allogeneic blood in specific situations.

Adult↗
PubMed1999

Acute hemodynamic effects of alternate and combined site pacing in patients after cardiac surgery.

We hypothesized that pacing at sites other than the right ventricular (RV) apex or at two or more ventricular sites would activate the myocardium more rapidly and improve cardiac function in patients undergoing coronary revascularization or aortic valve replacement. Epicardial electrodes were placed on the right atrium (A), RV paraseptal area close to the RV apex (B), RV outflow tract (C), LV apex (D), in patients undergoing bypass surgery. At constant rate and AV delay, we measured CO during A pacing, DVI pacing at B, C, D, and various combinations of sites in random order in ten patients with EF > 50% and 27 patients with EF < or = 50%. When pacing at two sites, we made one electrode a cathode and one an anode and noted two distinct thresholds by careful observation of the 12-lead ECG. There were no significant differences in CO, systemic vascular resistance, systolic, or mean arterial pressure. Significant differences were noted in QRS duration, which increased progressively going from AAI to 3-site, 2-site, and single site pacing (P < 0.05 each comparison). Thus: (1) QRS duration correlated inversely with the number of ventricular sites paced; (2) despite this, CO did not improve irrespective of baseline EF; (3) multisite pacing produced multiple distinct thresholds which appeared to be related to the number of sites paced, and (4) unique ECG patterns confirmed multisite pacing.

Aortic Valve↗
PubMed1999

Inhaled nitric oxide versus intravenous vasodilators in severe pulmonary hypertension after cardiac surgery.

UNLABELLED: Inhaled nitric oxide (iNO) is superior to i.v. vasodilators for treatment of pulmonary hypertension (PH) after cardiac surgery, but iNO is a potentially toxic gas, and patient subsets who benefit from iNO are not yet clearly defined. We administered iNO 40 ppm, prostaglandin E1 (PGE1) 0.1 microg x kg(-1) min(-1), and nitroglycerin (NTG) 3 to 5 microg x kg(-1) min(-1), in a randomized crossover study to 14 adult patients with severe PH after cardiac surgery. iNO, PGE1, and NTG were of similar efficacy in reducing pulmonary vascular resistance (P = 0.003). iNO induced selective pulmonary vasodilation, while PGE1 and NTG had significant concomitant systemic vasodilatory effects. iNO led to an increase in cardiac index (CI) (P = 0.012), and PGE1 increased CI (P = 0.006) and right ventricular (RV) ejection fraction (P = 0.015), while NTG had no effect on CI and RV performance. After study completion, patients continued with PGE1 administration with favorable in-hospital outcome. We conclude that PH per se, even if severe, does not necessarily imply postoperative RV dysfunction, and selective pulmonary vasodilation with iNO may not be superior to PGE1 with regard to CI and RV performance. IMPLICATIONS: In a prospective, randomized crossover study of inhaled nitric oxide (iNO) versus IV vasodilators, performed in adult patients with severe pulmonary hypertension but preserved right ventricular function after cardiac surgery, iNO was not superior to IV prostaglandin E1 with regard to cardiac index and right ventricular performance. Considering the potential toxicity of iNO, better definition of patient subsets with a positive benefit/risk ratio is warranted.

Administration, Inhalation↗
PubMed1998

Serum and CSF levels of neuron-specific enolase (NSE) in cardiac surgery with cardiopulmonary bypass: a marker of brain injury?

We investigated whether neuron-specific enolase (NSE) in serum or cerebrospinal fluid (CSF) reflects subtle or manifest brain injury in children undergoing cardiac surgery using cardiopulmonary bypass (CPB). NSE was measured in serum (s-NSE) before, and up to, 102 h after surgery in 27 children undergoing cardiac surgery with CPB. In 11 children, CSF-NSE was also measured 48 or 66 h post-surgery. As erythrocytes contain NSE, hemoglobin concentration in the samples was determined spectrophotometrically at 550 nm (cut-off limit: absorbance 0.4 = 560 mg/l) in 14 children and in a further 13 children by spectroscopic multicomponent analysis (cut-off limit 5 micromol/l = 80 mg/l). One hundred and one of 214 post-operative serum samples (47%) had to be discarded because of hemolysis (18% spectrophotometrically at 550 nm and 88% with spectroscopic multicomponent analysis). On the first and second post-operative day, the median s-NSE values were significantly higher when compared with samples taken after 54 h or longer (P = 0.008 and P = 0.002). All CSF-NSE levels were within the normal range and below the s-NSE measured in the same patient. Although in our study elevated s-NSE seems to indicate brain injury in CPB-surgery, the low concentration of NSE in the post-operative CSF of 11 children puts the neuronal origin of s-NSE in question. NSE from other non-neuronal tissues probably contributes to the elevated s-NSE. Additionally, normal post-operative CSF-NSE values in two children with post-operative neurological sequelae might question the predictive value of CSF-NSE with regard to brain injury.

Biomarkers↗
PubMed1998

Haemodilution tolerance in patients with mitral regurgitation.

Haemodynamic parameters and oxygen consumption were determined in 20 patients with mitral regurgitation before and after a 12 ml.kg-1 isovolaemic exchange of blood for 6% hydroxyethyl starch. During haemodilution, mean (SEM) haemoglobin concentration decreased from 13.0 (0.4) to 10.3 (0.4) g.dl-1 (p = 0.001). With cardiac filling pressures maintained at predilution levels, cardiac index increased from 1.84 (0.08) to 1.94 (0.08) l.min-1.m-2 (p = 0.025) while systemic vascular resistance decreased from 1556 (86) to 1425 (83) dyne.s.cm-5 (p = 0.002) and oxygen extraction increased from 31.7 (1.1) to 37.3 (1.4)% (p = 0.001) resulting in an unchanged oxygen consumption. The haemodynamic response to haemodilution was not affected by the patients' cardiac rhythm, i.e. whether it was sinus rhythm or atrial fibrillation. In conclusion, isovolaemic haemodilution to a haemoglobin of 10.3 g.dl-1 is well tolerated in patients with mitral regurgitation. Compensatory mechanisms include both an increase in cardiac index and an increase in oxygen extraction.

Aged↗
PubMed1997

Assay of S-ethyl-N-acetyl-l-cysteine in urine by high-performance liquid chromatography using post-column reaction detection.

The assay of the ethyl chloride metabolite S-ethyl-N-acetyl-L-cysteine in human urine by HPLC is described. The compound is enriched by adsorption on a non-polar adsorbent of graphitized non-porous carbon, and then stripped from positively charged compounds by application onto a strong acid cation-exchanger. Subsequently, an enzymatic deacetylation is carried out and the acylase is removed by centrifugal ultrafiltration. Separation of the sample is performed by cation-exchange chromatography applying an eluent of a very low elution strength (diluted formic acid). In the column effluent S-ethyl-L-cysteine is derivatized by o-phthaldialdehyde and the reaction product is detected by fluorescence measurement. In human urine a detection limit in the low ppb range is achieved.

Acetylation↗
PubMed1997

The effect of the N-methyl-D-aspartate receptor antagonist dextromethorphan on perioperative brain injury in children undergoing cardiac surgery with cardiopulmonary bypass: results of a pilot study.

Experimental evidence indicates a role of the N-methyl-D-aspartate receptor in the pathogenesis of brain injury occurring during cardiac surgery with cardiopulmonary bypass (CPB). Dextromethorphan is a noncompetitive antagonist of this receptor with a favorable safety profile. Thirteen children age 3-36 months undergoing cardiac surgery with expected CPB of 60 minutes or more were randomly assigned to treatment with dextromethorphan (36-38 mg/kg/day) or placebo administered by naso-gastric tube. Dextromethorphan was absorbed well and reached putative therapeutic levels in blood and cerebrospinal fluid. Adverse effects were not observed. Mild hemiparesis developed after operation in one child of each group, and severe encephalopathy in one of the placebo group. Sharp waves were recorded in postoperative continuous electroencephalography in all placebo (n = 7) but only in 2/6 dextromethorphan treated children (p = 0.02). Pre- and postoperative cranial magnetic resonance imaging (MRI) revealed less pronounced ventricular enlargement in the dextromethorphan group (not significant). An increase of periventricular white matter lesions was visible in two placebo-treated children only. No elevations of cerebrospinal fluid enzymes were observed in either group. Although children with dextromethorphan showed less abnormalities in electroencephalography and MRI, dissimilarities of the treatment groups by chance diminished conclusions to possible protective effects of dextromethorphan at this time.

Brain Chemistry↗
PubMed1997

Effects of chronic beta-blockade on compensatory mechanisms during acute isovolaemic haemodilution in patients with coronary artery disease.

We have compared compensatory mechanisms during acute isovolaemic haemodilution of 12 ml/kg body weight of blood with hydroxyethyl starch (450,000/0.7) exchange, in non-beta-blocked and beta-blocked patients with coronary artery disease. During haemodilution, mean concentrations of haemoglobin decreased from 12.8 (SEM 0.2) to 10.1 (0.1) g dl-1 (P < 0.01). Only beta-blocked patients had an increase in cardiac index (P < 0.01); in non-beta-blocked patients, cardiac index remained constant. In both groups oxygen extraction increased (P < 0.01), but the increase tended to be greater in non-beta-blocked patients (P = 0.06). Oxygen consumption was maintained in both groups. There were no ECG signs of myocardial ischaemia. We conclude that beta-blocked and non-beta-blocked patients with coronary artery disease tolerated well moderate haemodilution to a haemoglobin value of approximately 10 g dl-1, however, compensatory haemodynamic mechanisms differed fundamentally between the two groups.

Adrenergic beta-Antagonists↗
PubMed1996

Hemodilution tolerance in elderly patients without known cardiac disease.

Hemodilution tolerance is not well defined in elderly patients. In 20 patients older than 65 yr and free from known cardiovascular disease, hemodynamic variables, ST segment deviation, and O2 consumption were determined prior to and after 6 and after 12 mL/kg isovolemic exchange of blood for 6% hydroxyethyl starch. The mean age of the patients was 76 +/- 2 yr (mean +/- SEM, range 66-88 yr). During hemodilution, hemoglobin decreased from 11.6 +/- 0.4 to 8.8 +/- 0.3 g/dL (P < 0.05). With stable filling pressures, cardiac index increased from 2.02 +/- 0.11 to 2.19 +/- 0.10 L.min-1.m-2 (P < 0.05) while systemic vascular resistance decreased from 1796 +/- 136 to 1568 +/- 126 dynes.s.cm-5 (P < 0.05) and O2 extraction increased from 28.0% +/- 0.9% to 33.0% +/- 0.8% (P < 0.05) resulting in a stable O2 consumption during hemodilution. No alterations in ST segments were observed in lead II during hemodilution. In lead V5, ST segment deviation became slightly less negative during hemodilution from -0.03 +/- 0.01 to -0.02 +/- 0.01 mV (P < 0.05). The moderate decrease in hemoglobin was fully compensated by both an increase in cardiac index and in O2 extraction. Electrocardiographic signs of myocardial ischemia were not observed in this population. In conclusion, isovolemic hemodilution to a hemoglobin value of 8.8 +/- 0.3 g/dL is well tolerated in elderly patients free from known cardiac disease at the ages of 65-88 yr.

Abdomen↗
PubMed1996

Hemodilution tolerance in patients with coronary artery disease who are receiving chronic beta-adrenergic blocker therapy.

Hemodilution tolerance is not well defined in patients with coronary artery disease receiving beta-adrenergic blockers chronically. Ninety patients scheduled for coronary artery bypass graft (CABG) surgery were randomized to a hemodilution (n = 60) and a control group (n = 30). During midazolam-fentanyl anesthesia, hemodynamic variables, ST segment deviation, and O2 consumption were determined prior to and after 6 and 12 mL/kg isovolemic exchange of blood for 6% hydroxyethyl starch. Hemoglobin decreased from 12.6 +/- 0.2 to 9.9 +/- 0.2 g/dL (mean +/- SEM, P < 0.05). With stable filling pressures, cardiac index increased from 2.05 +/- 0.05 to 2.27 +/- 0.05 L.min-1.m-2(P < 0.05) and O2 extraction from 27.4% +/- 0.6% to 31.2% +/- 0.7% (P < 0.05), resulting in stable O2 consumption. No alterations in ST segments were observed in leads II and V5 during hemodilution. Individual increases in cardiac index and O2 extraction were not linearly related to age and left ventricular (LV) ejection fraction (P = 0.841, P = 0.799). We conclude that isovolemic hemodilution to a hemoglobin value of 9.9 +/- 0.2 g/dL is well tolerated and fully compensated in patients with coronary artery disease receiving beta-adrenergic blockers chronically. Within the investigated ranges, the compensatory mechanisms during hemodilution are largely independent of age (35-81 yr) and LV ejection fraction (26%-83%).

Adrenergic beta-Antagonists↗
PubMed1996

Primary structure of cyanelle peptidoglycan of Cyanophora paradoxa: a prokaryotic cell wall as part of an organelle envelope.

The peptidoglycan layer surrounding the photosynthetic organelles (cyanelles) of the protist Cyanophora paradoxa is thought to be a relic of their cyanobacterial ancestors. The separation of muropeptides by gel filtration and reverse-phase high-performance liquid chromatography revealed four different muropeptide monomers. A number of muropeptides were identical in retention behavior to muropeptides of Escherichia coli, while others had remarkably long retention times with respect to their sizes, as indicated by gel filtration. Molecular mass determination by plasma desorption and matrix-assisted laser desorption ionization mass spectrometry showed that these unusual muropeptides had molecular masses greater by 112 Da or a multiple thereof than those of ones common to both species. Fast atom bombardment-tandem mass spectrometry of these reduced muropeptide monomers allowed the localization of the modification to D-glutamic acid. High-resolution fast atom bombardment-mass spectrometry and amino acid analysis revealed N-acetylputrescine to be the substituent (E. Pittenauer, E. R. Schmid, G. Allmaier, B. Pfanzagl, W. Löffelhardt, C. Quintela, M. A. de Pedro, and W. Stanek, Biol. Mass Spectrom. 22:524-536, 1993). In addition to the 4 monomers already known, 8 dimers, 11 trimers, and 6 tetramers were characterized. An average glycan chain length of 51 disaccharide units was determined by the transfer of [U-14C]galactose to the terminal N-acetylglucosamine residues of cyanelle peptidoglycan. The muropeptide pattern is discussed with respect to peptidoglycan biosynthesis and processing.

Amino Acid Sequence↗