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Biomedical subjects

C Hörmann

Publications and source records attributed to C Hörmann.

At least 37 records · Page 2Linked to original sources
PubMed1998

Myocardial damage after minimally invasive coronary artery bypass grafting on the beating heart.

BACKGROUND: In conventional coronary artery bypass grafting, the rate of perioperative myocardial infarction is reported in the 2% to 6% range; however, significantly higher rates are observed if sensitive myocardial marker proteins are used to detect perioperative myocardial damage. For minimally invasive direct coronary artery bypass grafting, few data are available concerning myocardial marker protein release. METHODS: Fifteen consecutive patients (11 male, 4 female; mean age, 59.6 +/- 8.5 years) received minimally invasive direct coronary artery bypass grafting procedures via minithoracotomy on the beating heart. Electrocardiography and transesophageal and transthoracic echocardiography as well as determination of creatine kinase-MB mass concentration and cardiac troponin I level were used for ischemic monitoring. RESULTS: One patient had a perioperative myocardial infarction according to standard criteria and died despite mechanical circulatory support. Determination of cardiac troponin I level showed small but definitive ischemic damage in 4 of 9 patients (44%) who presented transient ischemic signs intraoperatively or postoperatively. In 2 of these 4 patients pathologic findings could be detected on angiographic restudies. CONCLUSIONS: Subclinical myocardial injury is a common event in minimally invasive coronary artery bypass grafting on the beating heart. Cardiac troponin I could serve as an adequate diagnostic tool for diagnosis of perioperative myocardial infarction in minimally invasive direct coronary artery bypass grafting.

Aged↗
PubMed1998

Single coronary artery bypass grafting--a comparison between minimally invasive 'off pump' techniques and conventional procedures.

OBJECTIVE: At present, few studies directly comparing minimally invasive and conventional coronary artery bypass grafting are available. The aim of the present study was to evaluate the clinical outcome of the two techniques. METHODS: We retrospectively compared our first consecutive 20 patients undergoing minimally invasive coronary artery single bypass grafting on the beating heart (group I) with 23 consecutive patients receiving single coronary artery bypass via sternotomy using cardiopulmonary bypass and cardioplegia (group II). The procedures were performed during the period from Jan 1, 1994 to Feb 20, 1997. There were no significant differences in demographic data. RESULTS: Statistically significant differences were found concerning total operative time (172.6 min in group I and 149.6 min in group II P = 0.0009) and myocardial ischemic time (23.7 min local coronary occlusion time in group I and 17.6 min aortic cross-clamp time in group II P = 0.03. Patients treated minimally invasive received significantly fewer blood transfusions (25.0% vs. 69.6% P = 0.0035) and were discharged significantly earlier from the hospital (admission rate on the fifth postoperative day 68.4% in group I vs. 100.0% in group II P = 0.0004). CONCLUSION: We conclude that minimally invasive coronary artery bypass grafting on the beating heart in comparison to conventional single coronary artery bypass grafting during the learning curve requires longer operative times but can reduce blood transfusion requirements and hospital stay.

Blood Transfusion↗
PubMed1998

Cardiopulmonary effects of aerosolized prostaglandin E1 and nitric oxide inhalation in patients with acute respiratory distress syndrome.

Ten patients with acute respiratory distress syndrome (ARDS) received in random order nitric oxide (NO) inhalation, aerosolized prostaglandin E1 (PGE1), infusion of PGE1, or no intervention. Inhalation of either aerosolized PGE1 (10 +/- 1 ng/kg/min) or NO (7 +/- 1 ppm) reduced pulmonary vascular resistance (PVR) from 158 +/- 14 to 95 +/- 11 dyn . s/cm5/m2 (NO) and 100 +/- 12 dyn . s/cm5/m2 (aerosolized PGE1), and improved PaO2 from 78 +/- 3 to 96 +/- 5 mm Hg (NO) and 95 +/- 4 mm Hg (aerosolized PGE1) (p < 0.05), venous admixture (Q VA/Q T) from 45 +/- 2 to 36 +/- 2% (NO), and 36 +/- 2% (aerosolized PGE1) (p < 0.05), oxygen delivery (DO2) from 711 +/- 34 to 762 +/- 45 ml/min/m2 (NO) and 780 +/- 46 ml/min/m2 (aerosolized PGE1) (p < 0.05), and right ventricular ejection fraction (RVEF) from 32 +/- 6 to 37 +/- 5% (NO), and 36 +/- 4% (aerosolized PGE1) (p < 0.05) at a constant cardiac index (CI). Although infusion of PGE1 (12 +/- 1 ng/kg/min) caused a similar reduction in PVR as aerosolized PGE1 and NO inhalation, it improved RVEF and increased CI but decreased Q VA/Q T and PaO2. These results suggest that in ARDS patients inhalation of aerosolized PGE1 or NO in low concentrations equally improves PVR and gas exchange by selective vasodilation in ventilated areas.

Administration, Inhalation↗
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↗
PubMed1997

Hypocapnia reverses the fentanyl-induced increase in cerebral blood flow velocity in awake humans.

Investigations on the effects of opioids on cerebrovascular dynamics have repeatedly demonstrated mild to moderate increases in cerebral blood flow velocity in the middle cerebral artery (CBFVMCA), cerebral blood flow, and cerebrospinal fluid pressure in humans and animals. However, the influence of hypocapnia on these fentanyl effects has not been investigated. We compared mean CBFVMCA during normo- and hypocapnia before and after administration of fentanyl (2.5 micrograms/kg i.v.) in 20 awake humans. During normocapnia (end-tidal carbon dioxide [ETCO2] 40 mmHg) fentanyl significantly increased mean CBFVMCA (60 +/- 10 cm/s vs. 81 +/- 12 cm/s [mean +/- SD]; p < 0.01), whereas during hypocapnia (ETCO2 25 mmHg) mean CBFVMCA values were identical (40 +/- 7 cm/s vs. 40 +/- 7 cm/s) before and after fentanyl administration. These results confirm previous findings that administration of fentanyl increases CBFVMCA, but, more importantly, clearly indicate that hypocapnia reverses this potentially undesirable effect.

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↗