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Biomedical subjects

M Hemmer

Publications and source records attributed to M Hemmer.

At least 19 recordsLinked to original sources
PubMed2001

Internet-assisted exercises in structural analysis.

In this report we describe our experience in the analytical chemistry curriculum of teaching spectrometer principles and preparing spectroscopy laboratory exercises by means of virtual instruments. The benefits of the intensified preparation of laboratory exercises by virtual instruments will be evaluated with respect to the subsequent handling of real instruments. The utilization of in-house electronic media with Internet resources for elucidation and verification of a structural assignment will also be considered.

Journal Article↗
PubMed2000

Comparative estrogenicity of estradiol, ethynyl estradiol and diethylstilbestrol in an in vivo, male sheepshead minnow (Cyprinodon variegatus), vitellogenin bioassay.

An in vivo bioasssay for vitellogenin (VTG) synthesis was developed to screen individual chemicals or mixtures of chemicals for potentially estrogenic effects in a marine teleost model. An enzyme-linked immunosorbent assay (ELISA) was used to quantitate VTG synthesis in male sheepshead minnows (Cyprinodon variegatus) exposed to five concentrations of the natural estrogen (17beta-estradiol), a synthetic, steroidal pharmaceutical estrogen (17alpha-ethynyl estradiol), or a synthetic, non-steroidal, pharmaceutical estrogen (diethystilbestrol) for 16 days. At an exposure concentration of 20 ng/l, only diethystilbestrol elicited a vitellogenic response. At all test concentrations greater than 100 ng/l, VTG appeared in the plasma in a dose-dependent manner for the three estrogen treatments. Liver VTG mRNA measurements were also made, exhibiting no clear correlations between quantities, nor temporal appearance of the message and mature protein were apparent. This assay is short-term, relatively inexpensive, shows a direct response, and easily quantitated.

Journal Article↗
PubMed1998

Confirmatory platelet-activating factor receptor antagonist trial in patients with severe gram-negative bacterial sepsis: a phase III, randomized, double-blind, placebo-controlled, multicenter trial. BN 52021 Sepsis Investigator Group.

OBJECTIVE: To determine the efficacy and safety of using natural platelet-activating factor receptor antagonist (PAFra), BN 52021, to treat patients with severe Gram-negative bacterial sepsis. DESIGN: A prospective, randomized, double-blind, placebo-controlled, multicenter clinical trial. SETTING: Fifty-nine academic medical center intensive care units in Europe. PATIENTS: Six hundred nine patients with severe sepsis, suspected to be related to Gram-negative bacterial infection, who received PAFra or placebo. INTERVENTIONS: Patients were randomized to receive either a dose of PAFra (120 mg iv) every 12 hrs over a 4-day period or placebo over a 4-day period. MEASUREMENTS AND MAIN RESULTS: The patients were well matched at study entry for severity of illness and for risk factors known to influence the outcome of sepsis. Among all randomized patients, the 28-day, all-cause mortality rate was 49% (152/308) in the placebo group, and 47% (140/300) in the PAFra group (p=.50). When analyzed on the basis of the previously defined target population, the 28-day, all-cause mortality rate was 50% (115/232) in the placebo group and 44% (94/212) in the PAFra group, yielding a 12% reduction in mortality rate (p=.29). In patients with documented infection involving other organisms, there was no difference between treated and placebo groups. When the outcomes of organ dysfunctions were examined in the overall population and in the documented Gram-negative bacterial infection population, the number of patients who resolved hepatic dysfunction tended to be higher in the treated group than in the placebo group (p=.06). The number of adverse events reported were not different between the two groups. CONCLUSIONS: A 4-day administration of the studied PAFra (BN 52021) failed to demonstrate a statistically significant reduction in the mortality rate of patients with severe sepsis suspected to be related to Gram-negative bacterial infection. If PAFra treatment has any therapeutic activity in severe Gram-negative bacterial sepsis, the incremental benefits are small and will be difficult to demonstrate in a patient population as defined by this clinical trial.

APACHE↗
PubMed1996

Short-term impact of the European Consensus Conference on the use of selective decontamination of the digestive tract with antibiotics in ICU patients.

Because it remained controversial, the use of selective digestive decontamination (SDD) in patients in the intensive care unit (ICU) was chosen as the topic of the first European Consensus Conference in Intensive Care Medicine (ECCICM) in December, 1991. The Consensus Bureau decided to assess the impact of this conference 2 years afterwards. For this purpose, a questionnaire was sent to the members of the European Society of Intensive Care Medicine, the Societé de Réanimation de Langue Française and the Societé Française d'Anesthesie et Réanimation before the conference. The recommendations following the conference discouraged the systematic use of SDD in ventilated patients and urged the monitoring of bacterial resistance and adapting antibiotics to epidemiology of the units. Two years after the conference, the same questionnaire was sent to those physicians who had responded to the first one. Eighteen percent used SDD for all ventilated patients and 17% remain users after 2 years. Among the occasional (32%) or continual (17%) users of SDD, the regimens used were mostly intravenous cefotaxime (60% of systemic antibiotics) and a topical combination of polymixin E, tobramycin, and amphotericin B (62% of overall topical combinations). The antibiotics used were unchanged after 2 years in almost all cases. In conclusion, the short-term impact of the Consensus Conference on SDD in ICU patients has been poor. This may be related to the continuing insufficiency of strong, definite data regarding the impact of this technique upon mortality and the theoretical risk of resistance to antibiotics, thus allowing physicians to stick to their policies until there is new evidence.

Anti-Bacterial Agents↗
PubMed1993

Incidence and risk factors of pneumonia acquired in intensive care units. Results from a multicenter prospective study on 996 patients. European Cooperative Group on Nosocomial Pneumonia.

OBJECTIVE: To estimate the incidence of pneumonia acquired in the intensive care unit (ICU), and to define risk factors for developing such an event. DESIGN: European prospective survey, in which all patients admitted to the participating ICU from January, 17 to 23, 1990, were followed until ICU discharge. SETTING: 107 general ICUs from 18 countries. PATIENTS: Of 1078 admitted to the ICUs, 996 patients without pneumonia at admission were studied. MEASUREMENTS: Pneumonia was diagnosed by the staff physician on the basis of clinical, radiological and microbiological criteria, secondly validated by an expert committee who reviewed all the forms and even recontacted ICU physicians. Crude incidence and time to occurrence of pneumonia were estimated, then both used as end-points for prognosis analysis. RESULTS: 89 pneumoniae were observed: crude incidence was estimated at 8.9% 7-day and 14-day pneumonia rates at 15.8% and 23.4%, respectively. The risk of developing pneumonia increased when either coma, trauma, respiratory support, Apache II > 16 and/or imparied air-way reflexes were present at ICU admission. To predict time to occurrence of pneumonia, only two variables remained significant: the presence of impaired airway reflexes at admission and the use of mechanical ventilation during ICU course. CONCLUSIONS: The role of the injury to the respiratory system-with the subsequent need for respiratory support--appears central in determining the risk to acquire pneumonia in ICU. In the future, the predictive value of severity scores during ICU course should be otherwise assessed.

Adult↗
PubMed1980

Urinary antidiuretic hormone excretion during mechanical ventilation and weaning in man.

The authors measured antidiuretic hormone (ADH) excretion and renal and cardiovascular function in eight patients with flail chest during four ventilatory conditions: continuous positive-pressure ventilation (CPPV), intermittent positive pressure ventilation (IPPV), spontaneous breathing with continuous positive airway pressure (CPAP) and spontaneous breathing (SB). Each condition was maintained for six to eight days. ADH excretion was significantly greater during CPPV (181 +/- 14 ng/24 h, mean +/- SE) than during IPPV (86 +/- 10), CPAP (181 +/- 14 ng/24 h, mean +/- 6). Free-water clearance was more negative during mechanical ventilation than during CPAP and SB, resulting in significant fluid retention during CPPV and IPPV (440 +/- 88 and 547 +/- 70 ml/day) and a negative water balance during SB (-154 +/- 80 ml/day). Arterial and central venous pressures and cardiac output (measured in four patients) did not change significantly among ventilatory conditions. It is concluded that ADH excretion is increased during CPPV, and this could represent one possible mechanism of water retention with this type of ventilation.

Adult↗
PubMed1979

Treatment of cardiac and renal effects of PEEP with dopamine in patients with acute respiratory failure.

The hemodynamic and renal effects of mechanical ventilation with positive end-expiratory pressure (PEEP) were studied with and without continuous dopamine administration in ten patients who had acute pulmonary failure. The application of 20 cm H2O PEEP during mechanical ventilation resulted in improvements in arterial blood oxygen tension, from 63 +/- 6 to 81 +/- 12 torr (mean +/- SE), and intrapulmonary shunt fraction, from 29 +/- 3 to 21 +/- 3 per cent, whereas cardiac output, systemic oxygen transport and renal function were impaired by 20, 19 and 47 per cent, respectively. Dopamine infusion at a rate of 5 +/- 0.05 micrograms/kg/min reversed the deleterious effects of PEEP on cardiovascular and renal function: cardiac output increased from 4.5 +/- 0.3 to 6.0 +/- 0.51, urinary output from 1.0 +/- 0.3 to 1.7 +/- 0.4 ml/min, sodium excretion and creatinine clearance by 50 per cent. Systemic oxygen transport was improved from 680 +/- 44 to 925 +/- ml, arterial oxygen tension from 81 +/- 12 to 102 +/- 14 torr, and total deadspace to tidal volume ratio from 0.49 +/- 0.02 to 0.44 +/- 0.03 with dopamine. The authors conclude that the depression of cardiovascular and renal functions that may occur in patients who need high levels of PEEP for the treatment of acute pulmonary failure can be treated successfully with dopamine infusion. This represents a valuable alternative to expansion of blood volume for the improvement of systemic oxygen transport and arterial blood oxygen tension in critically ill patients.

Adult↗
PubMed1978

[Ventilatory support after open heart surgery: effects of PEEP and CPAP on gas exchange and lung function (author's transl)].

In 11 patients requiring coronary bypass surgery during extracorporeal circulation we measured pulmonary function and hemodynamic variables before surgery and during the postoperative period. None of the patients presented with pulmonary hypertension or cardiac failure. Cardiac surgery with extracorporeal circulation caused an important decrease in functional residual capacity (-60%) and in arterial oxygenation (-44%). In the immediate postoperative period, the addition of a positive end-expiratory pressure (PEEP) to mechanical ventilation produced an increase in functional residual capacity and in arterial oxygen tension, and a slight decrease in cardiac output. In contrast to the results obtained in children after cardiac surgery and in adults presenting with viral pneumonia or respiratory distress after polytrauma or surgery, continuous positive airway pressure during spontaneous breathing (CPAP) did not improve pulmonary gas exchange in our patients, despite the significant increase in functional residual capacity produced. This suggests that CPAP did not cause recruitement of atelectatic areas or that this effect was offset by a parallel overdistension of gas exchange units.

Adult↗
PubMed1977

[The effects of the pause at the end of inspiration on gas exchange and hemodynamics during artificial ventilation].

We have studied the effects of an inspiratory pause (PI) during artificial ventilation in 13 patients in acute respiratory insufficiency. The effects on gas exchange, haemodynamics and distribution of ventilation were observed. During the period of study the total volume, the inspiration/expiration ratio and the inspired oxygen concentration were all maintained constant. With the inspiratory pause arterial oxygenation has not changed significantly, whereas it did change favourably with PEEP. The physiological dead space (VD/VT) was reduced in proportion to the duration of the inspiratory pause. These results suggest that the inspiratory pause triggers regional modification of the ventilation/perfusion ratio, favouring a reduction of the VD/VT ratio. However, this improvement of the VD/VT ratio does not seem to influence the oxygenation or the total distribution of ventilation in this type of patient.

Adult↗
PubMed1976

Cardiocirculatory and biochemical effects of dextran 1.8% and ringer's lactate after minor surgical procedures.

The effects of dextran 1.8% in Ringer's lactate solution were compared with infusion of Ringer's lactate alone in two groups of 12 patients after minor surgical interventions. Plasma volume increased significantly only in the dextran treatment patients. We observed a marked hemodilution with both infusions, but all changes had disappeared after 24 hours. No adverse effects on the coagulation process, hepatic and renal function were noted. These results suggest that dextran 1.8% in Ringer's lactate is an effective and safe solution in plasma volume expansion for this type of patient.

Adolescent↗
PubMed1975

[Clinical investigations of the steroid anaesthetic agent CT-1341 (Althesin) (Cardiovascular and respiratory effects)].

The new steroid anaesthetic CT-1341 (Althesin) has been used as an induction agent in dose of 0.07 ml/kg body weight. Following injection, stage 1 anaesthesia is reached in an average of 30 sec with a clinical duration of between 12 and 20 min with total recovery, supported by a normal pre-anaesthetic EEG tracing, in 40 to 50 min. The respiratory depression following injection in characterized by a short period of apnea followed by an increased respiratory rate and a diminished tidal volume; there is a decrease of the pO2 of about 15%, but the pCO2 and pH values do not show significant variations. Concerning its action on the cardiovascular system, there was found an increase of heart rate (+14%), a decrease of both systolic (-19%) and diastolic pressures (minus decrease of both systolic (-19%) and diastolic pressure (-13.5%), central venous pressure and the peripheral vascular resistance (-14%) with hardly any change in the pulmonary artery pressure.

Adult↗
PubMedDate not supplied

Tension mediastinal emphysema: emergency percutaneous drainage with CT guidance.

Four patients aged 8 to 54 years, under mechanical ventilation, presented with sudden tension mediastinal emphysema and exhibited typical clinical symptoms of compromised venous return. Diagnosis of tension mediastinal emphysema was confirmed by CT. A percutaneous catheter with a diameter varying from F12 to F20 was inserted in the anterior mediastinal compartment with CT control and connected to a waterseal aspiration. Emergency treatment was efficient in all patients. Percutaneous aspiration was continued for 3 to 20 days.

Adult↗