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Biomedical subjects

C Hörmann

Publications and source records attributed to C Hörmann.

At least 19 recordsLinked to original sources
PubMed1997

Augmented release of brain natriuretic peptide during reperfusion of the human heart after cardioplegic cardiac arrest.

The aim of the study was to investigate the release of natriuretic peptides during myocardial ischaemia and reperfusion associated with cardioplegic cardiac arrest. Brain natriuretic peptide (BNP) and atrial natriuretic peptide (ANP) concentrations were measured in paired arterial, central venous and coronary sinus blood samples in 19 patients undergoing elective coronary artery bypass grafting before aortic crossclamping and 1, 5, 10 and 20 min after aortic declamping. Peak myocardial BNP release after aortic declamping was significantly higher than baseline values before aortic crossclamping. Both peak and cumulative BNP release during reperfusion correlated significantly with the severity of ischaemia, as assessed by myocardial lactate production. In 3 patients with perioperative myocardial ischaemia, cumulative and peak myocardial BNP release after aortic unclamping was markedly higher than in the remaining 16 uneventful patients. Myocardial ANP release during reperfusion was not significantly different from baseline values before aortic crossclamping. In conclusion, our data demonstrate a significantly enhanced myocardial BNP release early during reperfusion of the human heart after global ischaemia associated with cardioplegic cardiac arrest.

Adult↗
PubMed1997

Inhalation injury treated with extracorporeal CO2 elimination.

A 38-year-old male was admitted to the intensive care unit with a full-thickness burn involving 30 per cent of his total body surface area (TBSA) and severe inhalation injury. Respiratory failure developed within 54 h and CO2 could not be eliminated, even by very invasive mechanical ventilation. Because of the patient's age and the minor extent of the burned TBSA, we started extracorporeal CO2 elimination (ECCO2-R) and continued ECCO2-R for 30 days, when the patient was weaned from ECC. The clinical course during ECCO2-R was complicated by major bleeding from a thoracotomy tube, from the site of tangential excision and by four septic episodes. Lung biopsy was performed twice on day 29 (during ECCO2-R) and day 58 (after ECCO2-R) after admission and revealed bronchiolitis obliterans without tendency to recovery. The patient died of sepsis with multiorgan failure on day 81 after trauma.

Adult↗
PubMed1997

Quotation accuracy in neuroanesthesiologic research.

A considerable number of quotational inaccuracies have been detected in medical and surgical publications in the past. Our study investigated the quotational accuracy of selected references of 32 scientific publications in six anesthesia journals referring to a single article published in a 1973 issue of the British Journal of Anaesthesia. In four (12.5%) articles, the quotation was in contradiction to the primary author's statement; in 15 (46.9%) articles, it was selective; and in 13 (40.6%) publications, it was in complete agreement with the important statements made in the original article. These results suggest that quotational inaccuracy is also evident in neuroanesthesiologic research. This problem deserves increased attention by authors as well as by reviewers and journal editors.

Anesthesiology↗
PubMed1997

Effects of normo- and hypocapnic nitrous-oxide-inhalation on cerebral blood flow velocity in patients with brain tumors.

Nitrous oxide (N2O) use during anesthesia for intracranial procedures has been a subject of controversy in the past. To date, the isolated influence of N2O on mean cerebral blood flow velocity in the middle cerebral artery (VMCA) has not been investigated during hypocapnia in patients with brain tumors. We compared VMCA during normocapnic (ETCO2: 40 mm Hg) and hypnocapnic (ETCO2: 25 mm Hg) inhalation of air and 50% nitrous oxide in oxygen N2O/O2 in eight patients with unilateral brain tumors on both the tumor side and the healthy side. Six patients completed the study. Mean VMCA increased during normocapnic inhalation of N2O/O2 (tumor side: 86 +/- 16 cm sec-1; healthy side: 74 +/- 17 cm sec-1) when compared with air (tumor side: 72 +/- 18 cm sec-1; healthy side: 62 +/- 14 cm sec-1, p < 0.01), whereas during hyperventilation VMCA decreased on both sides (p < 0.001). Mean VMCA values were quite similar during hypocapnic inhalation of 50% N2O/O2 (tumor side: 50 +/- 12 cm sec-1; healthy side: 45 +/- 13 cm sec-1) and air (tumor side: 51 +/- 14 cm sec-1; healthy side: 45 +/- 12 cm sec-1). The data of our study suggest that in patients with cerebral tumors the N2O-induced increase in mean VMCA can be completely reversed by hyperventilation.

Adult↗
PubMed1996

Comparison of different modes of high-frequency ventilation in surfactant-deficient rabbits.

Various modes of high-frequency ventilation (HFV) have been developed to avoid the disadvantages of conventional mechanical ventilation. In the present study, we examined the hypothesis that high-frequency oscillation (HFO) is superior to high-frequency positive pressure ventilation (HPPV) and combined high-frequency ventilation (CHFV) in surfactant-deficient rabbits. The aim of the ventilator strategy was to adjust the mean airway pressure to 2 cm above critical opening pressure of the inflation limb of the respiratory system pressure volume (P/V) curve, achieve a normal tidal volume (VT) (5 ml/kg body weight) and apply repeated sustained inflations. We studied the effect of these HFV modes on oxygenation, lung mechanics and lung histology in 15 New Zealand White rabbits during a 6-hour experiment. Statistically, the HFO group demonstrated significantly better oxygenation (P < 0.05), lung mechanics (lung stability index: P < 0.05), and better lung tissue histology compared to the HPPV and CHFV groups. In contrast to the HPPV and CHFV groups, the P/V curves of the HFO group showed significant recovery over the 6-hour period after lavage. The lungs of the HFO-treated group had a more uniform distribution of alveoli and less overdistention than the HPPV group (P < 0.002), and less atelectasis than the CHFV group (P < 0.05). The HFO group had less lung injury than the CHFV groups (P < 0.01) and its lungs contained significantly less water than both other groups (P < 0.05). We conclude that the relationship between mean and end-expiratory pressures impacts strongly on both oxygenation and the progression of injury during HFV at the same mean airway pressures. The HFO group showed less acute lung injury than the other ventilatory groups.

Animals↗
PubMed1996

Surfactant replacement therapy in acute respiratory distress syndrome from viral pneumonia.

A modified natural surfactant was administered to a patient with life-threatening adult respiratory distress syndrome caused by viral pneumonia. Subsequently, there was a marked improvement in gas exchange. In order to assess the mechanism for improved oxygenation, computed tomography of the lungs was done. Quantitative analysis of the scans taken before and after surfactant administration indicates that improvement in gas exchange was largely due to the expansion of underinflated and collapsed lung areas. Although this is a single case report, it provides insight into the possible beneficial effect of instilled surfactant in severe respiratory distress from viral pneumonia.

Biological Products↗
PubMed1995

Influence of urapidil on cerebrospinal fluid pressure in humans with uncompromised intracranial compliance.

OBJECTIVE: Determine the influence of urapidil on mean lumbar cerebrospinal fluid pressure (CSFP), mean arterial pressure (MAP), mean central venous pressure (CVP) and heart rate (HR) in awake humans without any evidence of cerebral or cardiovascular disease. DESIGN: Open, single-dose volunteer study. INTERVENTIONS: CSFP was measured via a spinal needle after i.v. injection of a single dose of 0.2 mg kg-1 urapidil in six volunteers (2 female, 4 male). MEASUREMENTS AND RESULTS: After administration of urapidil, CSFP increased from 7 +/- 1 mmHg to 10 +/- 1 mmHg (p < 0.05), MAP decreased from 88 +/- 7 mmHg to 74 +/- 5 mmHg (p < 0.05), CPP decreased from 81 +/- 7 mmHg to 64 +/- 5 mmHg (p < 0.05) and CVP decreased from 0 +/- 1 mmHg to -3 +/- 1 mmHg (p < 0.05). CONCLUSION: Our data suggest that in humans with presumed normal intracranial compliance the administration of urapidil causes a small but statistically significant increase in CSFP due to a parallel decrease in MAP.

Adult↗
PubMed1995

Hemodynamics and oxygen metabolism in the pig during long-term hypothermia: comparison of 2 pH strategies.

The aim of this study was to investigate the influence of acid-base management (pH stat or alpha stat) on hemodynamics and oxygen metabolism during long-term hypothermia in the pig. Seventeen female pigs were anesthetized, slowly cooled to 28 degrees C with cooling mats and kept at this temperature for 36 h. Thereafter, slow rewarming was performed with inhalation of a 40 degrees C warm air/oxygen mixture and insulation. Eight of the 17 pigs were ventilated according to the pH stat strategy and 9 according to the alpha stat strategy. Both groups were compared 4 times each for hemodynamics and metabolism during cooling, hypothermia and rewarming. The 2 strategies showed no significant difference in cardiac output, heart rate or mean arterial pressure. The only difference in hemodynamics was observed in mean pulmonary artery pressure and pulmonary artery resistance during hypothermia, showing higher values in pH stat animals. As for oxygen metabolism, oxygen consumption during hypothermia was significantly higher in alpha stat animals. Long-term hypothermia with spontaneous circulation revealed significant differences in oxygen metabolism and pulmonary artery pressure as well as resistance between alpha and pH stat acid-base management. These differences may be of importance when using moderate hypothermia in a clinical or experimental setting.

Acid-Base Equilibrium↗
PubMed1995

Hyperventilation reverses the nitrous oxide-induced increase in cerebral blood flow velocity in human volunteers.

Because hypocapnia is routine during general anaesthesia for intracranial procedures, we have compared, in 13 healthy volunteers, the effect of normocapnia (PE'CO2 5.3 kPa) and hypocapnia (PE'CO2 3.3 kPa) on mean blood flow velocity in the middle cerebral artery (Vmca) during normoventilation and hyperventilation with air and with 50% nitrous oxide in oxygen. After replacement of air with 50% nitrous oxide in oxygen, there was an increase in mean Vmca during normoventilation (air: mean 68.23 (SD 16.98) cm s-1 vs nitrous oxide in oxygen: 90.69 (20.41) cm s-1; P < 0.01), whereas during hyperventilation mean Vmca values were similar regardless of the inhaled gas mixture (air: 43.46 (9.97) cm s-1 vs nitrous oxide in oxygen: 41.69 (8.08) cm s-1. Our data suggest that the nitrous oxide-induced increase in mean Vmca can be blocked by hyperventilation.

Adult↗
PubMed1995

Low-dose sufentanil increases cerebrospinal fluid pressure in human volunteers.

Although sufentanil is frequently used in neuroanesthesia, the effect of the drug on intracranial pressure is still controversial. In our study, we used an invasive measurement technique to study the effects of 0.1 micrograms/kg-1 sufentanil on mean lumbar cerebrospinal fluid pressure (CSFP), mean arterial pressure (MAP), cerebral perfusion pressure (CPP), central venous pressure (CVP), heart rate (HR), and end-tidal dioxide (ETCO2) in five human volunteers. After i.v. injection of sufentanil, mean lumbar CSFP increased from 6 mm Hg to 12 mm Hg (p < 0.05), and mean CPP decreased from 92 mm Hg to 78 mm Hg (p < 0.05), whereas MAP, CVP, HR, and ETCO2 remained stable. The results of this study clearly show that even a low dose of sufentanil transiently increases lumbar CSFP in volunteers with uncompromised intracranial compliance.

Adult↗
PubMed1994

[The prone position in ARDS. A successful therapeutic strategy].

As early as 1974, Brian advocated the prone position for ventilated patients. He suggested that this position might enhance ventilation of the dorsal parts of the lungs, thereby improving oxygenation. These considerations have been confirmed by several experimental and clinical studies. Better secretion removal, decreased intrapulmonary shunting, and an increased FRC are thought to be responsible for the observed improvement of oxygenation. However, the prone position never became very popular in the clinical treatment of the adult respiratory distress syndrome (ARDS). Routine performance of thoracic CT scans in ARDS patients demonstrated preferential distribution of pathological densities in the dependent lung areas. The prone position therefore could possibly benefit these patients, as shown by two recent studies. The aim of our study was to evaluate the influence of repeatedly turning the patient to the prone position on gas exchange and thoracic CT findings in multiple-trauma patients. METHODS. Seven ventilated intensive care patients with severe ARDS (Murray Score > 2.5, Quotient > 0.7, mean airway pressure > 18 cm H2O, thoracic CT scan showing dorsal atelectases) were included in the study. Patients were turned from the supine to the prone position at 12-h intervals using an air-cushion bed (Mediscus, Austria). Redistribution of dystelectatic or atelectatic dependent lung areas was verified by means of repeated thoracic CT scans (Figs. 1, 8). RESULTS. The patients were intermittently turned for 6.5 +/- 1.1 days. The course of gas exchange is shown in Figs. 2 and 3. Initially, improvement of the respiratory quotient could only be achieved during prone positioning, from the 2nd day in the supine position as well. Intrapulmonary shunting showed a similar trend (Figs. 4 and 5). No significant changes in cardiovascular parameters could be observed. Control thoracic CT scans showed uniform reduction of atelectases in dependent lung areas (Figs. 1 and 8). The inspiratory fraction of oxygen could be reduced significantly as of the 2nd day (Fig. 7). Constant levels of positive end-expiratory pressure and tidal volume were associated with decreasing mean and plateau airway pressures (Fig. 6). DISCUSSION. Repeatedly turning the patient to the prone position produced long-lasting improvement of arterial oxygenation, which persists up to the end of the weaning process. This is in good accordance with other studies, however, this is the first study to report an observation period of more than 6 days of repeatedly turning the patient. These positive effects on gas exchange can be attributed to sudden improvement of the ventilation-perfusion ratio within the lung areas that become dependent after turning to the prone position. Due to reduced hydrostatic pressure and relative hyperventilation, previously collapsed alveoli are recruited in the lung areas that become non-dependent after turning to the prone position.

Adult↗
PubMed1994

Subglottic positive end-expiratory pressure in extubated patients recovering from acute lung injury.

OBJECTIVE: To examine the glottic function in extubated patients recovering from acute lung injury by simultaneous measurement of airway opening and subglottic airway pressures while patients are breathing at ambient pressure and receiving continuous positive airway pressure by a face mask. DESIGN: Descriptive, prospective study. SETTING: Intensive care unit at a university hospital. PATIENTS: Ten patients who required continuous positive airway pressure of at least 7 cm H2O in order to restore gas exchange after mechanical ventilation for acute lung injury. INTERVENTIONS: Spontaneous breathing at ambient airway pressure and with continuous positive airway pressures of 5 and 10 cm H2O via face mask. MEASUREMENTS AND MAIN RESULTS: Intratracheal pressure, airway opening pressure, and airflow at the airway opening were measured. Breathing at ambient pressure resulted in significantly higher end-expiratory intratracheal pressure than end-expiratory airway opening pressure (p < .01). No significant differences between end-expiratory intratracheal pressure and end-expiratory airway opening pressure were observed during breathing with continuous positive airway pressures of 5 and 10 cm H2O. A significant end-expiratory airflow at the airway opening (p < .01), observed during ambient pressure breathing, was not detectable while the patient received mask continuous positive airway pressure. The partial pressure of oxygen in the arterial blood (Pao2) increased significantly while patients breathed with 10 cm H2O, but not while patients breathed 5 cm H2O continuous positive airway pressure compared with breathing at ambient pressure (p < .05). CONCLUSIONS: Our data imply that patients recovering from acute lung injury create an intratracheal positive end-expiratory pressure by braking the expiratory airflow, probably by glottic narrowing. Despite compensatory glottic narrowing, extubated patients with reduced lung function may benefit from higher levels of continuous positive airway pressure.

Adolescent↗
PubMed1994

Continuous positive airway pressure breathing increases cerebral blood flow velocity in humans.

The effect of a continuous positive airway pressure (CPAP) of 12 cm H2O on mean middle cerebral artery flow velocity (CBFV) was studied in nine human volunteers by means of transcranial Doppler sonography (TCD). During CPAP breathing, CBFV increased (45 +/- 9 vs 59 +/- 11 cm/s; P < 0.001; mean +/- SD), and pulsatility index (PI) decreased (0.87 +/- 0.1 vs 0.74 +/- 0.2; P < 0.05), indicating an increase in cerebral blood flow due to cerebral vasodilation. This phenomenon should be taken into account when CPAP is applied to patients with intracranial disease or when assessing CBFV patterns of patients during CPAP respiration.

Adult↗
PubMed1994

[Errors in ventilation therapy].

In spontaneous breathing intrathoracic pressure alternates between positive and negative in a biphasic sequential pattern. By contrast, during mechanical ventilation (IPPV, CPPV) the intrathoracic pressure remains above atmospheric all the time. Due to these unphysiological conditions there are extensive causal and side effects on the lung parenchyma and other organs. Errors in the artificial ventilation technique can magnify these effects. In order to minimize these deleterious effects of positive pressure ventilation it is essential to keep the procedure as short and little invasive as possible. The following strategy enables this goal to be brought closer: 1) early commencement of ventilation; 2) optimal adjustment of artificial ventilation to the individual needs of the patient, 3) early weaning from assisted ventilation through augmented rather than controlled modes of ventilation: 4) kinetic therapy (systematic changing of the patient's position) with the back up of the requisite thoracic CT scan findings; 5) reduction of the invasiveness of the procedure in order to ensure early commencement of spontaneous respiration.

Humans↗
PubMed1994

Biphasic positive airway pressure (BIPAP)--a new mode of ventilatory support.

Biphasic Positive Airway Pressure (BIPAP) can be described as pressure controlled ventilation in a system allowing unrestricted spontaneous breathing at any moment of the ventilatory cycle. It can also be described as a Continuous Positive Airway Pressure (CPAP) system with a time-cycled change of the applied CPAP level. As with a pressure controlled, time-cycled mode, the duration of each phase (T(high), T(low)) as well as the corresponding pressure levels (P(high), P(low)) can be adjusted independently. Depending on the spontaneous breathing activity, BIPAP can be subdivided into: no spontaneous breathing: CMV-BIPAP; spontaneous breathing at the lower pressure level: IMV-BIPAP; spontaneous breathing at the upper pressure level: APRV-BIPAP; spontaneous breathing at both CPAP levels: genuine BIPAP. Since it enables progressive transition from controlled to all levels of augmented mechanical ventilation, BIPAP appears to be a suitable mode for the entire period of mechanical ventilation of the patient. There are difficulties neither in choosing the correct moment for switching nor the further respiratory management of the ventilated patient under BIPAP. The necessary adaptation (ventilation, oxygenation) can be individualized on the basis of blood gas analyses. An increase or reduction of the invasivity of ventilation can be attained without any problems with BIPAP. Furthermore, spontaneous breathing of the patient does not necessitate any switching of the mode of ventilation. The transition from controlled to augmented ventilation is smooth. BIPAP enables the therapist to let the patient breathe freely even under the most invasive ventilation conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗